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Painted Hills FEIS Appendix P - MAY 2023APPENDIX P: Revised Flood Control Narrative This page intentionally left blank. WCE No. 2013-1166 Revised March 6, 2019 City of Spokane Valley 11707 E Sprague Ave, Suite 106 Spokane Valley, WA 99206 IWC E Whipple Consulting Engineers, Inc. Attn: Mr. Henry Allen, P.E. Re: Painted Hills Flood Control Development Narrative Dear Henry: This letter is provided as a description of the flood control plan associated with grading and site improvements that would be completed in conjunction with a future mixed-use development on approximately 99.5-acres of a former golf course property located at 4403 S Dishman-Mica Road. It is intended as an update to previous flood control narrative descriptions provided to the City by Whipple Consulting Engineers dated July 23, 2015, October 13,2016, and July 6, 2017. Since the date of the last narrative provided to the City, the applicant has modified the proposed site design in order to obtain a Conditional Letter of Map Revision (CLOMR) from the Federal Emergency Management Agency (FEMA). This design update to obtain a CLOMR using fill approval represents a change in the FEMA re-map effort for the project, which was formerly designed to revise the FEMA mapping through a Conditional Letter of Map Revision (CLOMR) process resulting from levee improvements and levee certifications. This change to a CLOMR using fill was implemented due to concerns raised by the City at a meeting held on November 9th. 2017 wherein long-term levy maintenance was questioned by City staff. A call between FEMA representatives, WCE, WEST, and City staff occurred on January 18, 2018. The project site is located within the area identified as Storage Area 1 (SA1) in the effective FEMA Flood Insurance Study (FIS). SA 1 is designated as a compensatory storage area. Within a compensatory storage area loss of flood storage capacity due to placement of fill must be mitigated with an equivalent compensatory volume of storage or through a reduction in flows such that the net condition causes no adverse impact to the base flood or floodway elevations within the storage area. In addition, loss of infiltration capacity due to placement of fill or impervious surfaces must be mitigated in such a way that the decrease in infiltration capacity will cause no adverse impact to the base flood or floodway elevations within the storage area. The overall purpose of the "compensatory" requirement is to ensure that development activities do not cause an adverse impact on flood elevations within the storage area, or downstream of the development (e.g. increasing downstream flows due to reduced infiltration capacity within the storage area). With the current plan to pursue a CLOMR using fill, the applicant is proposing to control and manage floodwaters and address compensatory storage requirements on the site through a combination of on-site fill, enhanced conveyance facilities (culverts) and infiltration galleries. Chester Creek main channel will remain unchanged, even with the widening of Thorpe Road which uses a box culvert to rest over the exiting channel. The intent of the Painted Hills PRD flood control design is to mimic the flood control project that Spokane County did on the Chester Creek mainstem, when the Kokomo area was taken out of the flood plain, by digging two deep borrow pits just West of Dishman-Mica Road and South of 28th Avenue. 21 South Pines Rd. • Spokane Valley, WA 99206 1 PO Box 1566 • Veradale, WA 99037 Phone 509-893-2617 • Fax 509-926-0227 • WhippleCE.com • Info@WhippleCE.com Civil, Structural, Traffic, Survey, Landscape Architecture and Entitlements Painted Hills Flood Control Development Narrative (Storage Area #1 & #6) Revised March 6, 2018 Page 2 of 6 This narrative restates and clarifies background information regarding the FEMA mapping for the site and further describes the current proposed plan. MAPPED FLOODPLAIN CONDITIONS History of Site Flood Analysis (source: BSW Painted Hills PRD) A hydrologic and hydraulic analysis for Chester Creek Basin was completed by Michael Baker Jr., Inc. and approved by Spokane County in a letter to the Federal Emergency Management Agency dated August 6, 1990. There are no long-term gage records for Chester Creek. The limited gage measurements on Chester Creek were collected near the Dishman-Mica Road crossing of Chester Creek for December 1994 through March 1995 and November 1995 through February 1996 when no significant flood events occurred. In February 2006, the hydraulic analysis for Chester Creek was revised by WEST Consultants, Inc. under a FEMA contract. The analysis established updated flood magnitude-frequency estimates for the watercourse. A steady flow hydraulic model has been developed for Chester Creek. The reports concluded that spring floods in the upper Spokane River basin are due to snowmelt runoff from high elevation watersheds. Such floods are of less significance on Chester Creek because of the lower elevation of the water shed limit and the size of the snowpack. Spring runoff occurs about a month earlier with the more gradual rates than on the Spokane River. Nearly all maximum annual flood peaks on Chester Creek occur during the winter. Warm winds and rain can melt the snow rapidly. When winter rain causes snowmelt on partially frozen soil conditions, short-duration, intense runoff generates a flood peak during winter storms. During the more extreme events, Chester Creek runs over its banks filling localized depressions in the flood zone. The duration of flooding is generally between 100 hours and 1000 hours, or between four days and forty days with smaller events occurring with greater frequency than large events. 1 Channel geometry for Chester Creek was developed from surveys conducted in March 2003. Overbank geometry was developed from topography developed by TerraPoint (2003). Flood plain boundaries for Chester Creek and the Unnamed Tributary to Chester Creek were delineated using 2-foot contour interval maps developed by TerraPoint from LiDAR data. A watershed plan for Chester Creek was previously designed with management recommendations for drainage, flooding, water quality, and riparian habitat. As a result, flood control improvements have been implemented along Chester Creek. The improvements to the area began at the Painted Hills Golf Course. In 1998, a project to install new culverts and extensive dredging of the channel between Thorpe Road and Schafer Road was implemented. Two large volume borrow pits were constructed downstream. Each pit was designed for the retention and infiltration of Chester Creek floodwaters up to a 25-year event. One borrow pit for the unnamed Tributary to Chester Creek was constructed just north of E 40th Avenue and the other borrow pit for Chester Creek just West of Dishman Mica and South of 28th Avenue. Before the storage areas #1 (compensatory area) and #6 (triangle pond) are to be modified (see Site Element Plan), it is important to understand where they are within the Chester Creek Basin, and what floodwaters they receive. Within the Chester Creek Basin, the storage areas are generally located in the northeast corner of the basin along the edge of the valley floor. Specifically, north of Thorpe Road and along Madison Road (Storage Area 1) and to the northeast of 40th Avenue (Storage Area 6). The flood condition flows, as identified by WEST Consultants, are separated into three parts in relation to the three directions of flow that enters into the Painted Hills Development: the main flow (Golf Course Overflow Reach) across Thorpe Road, the secondary (Unnamed Tributary) flow from Highway 27, and the secondary flow across Madison Road. The project is proposing to redirect the anticipated flows of the Painted Hills Flood Control Development Narrative (Storage Area #1 & #6) Revised March 6, 2018 Page 3 of 6 identified flood events for storage area #1 (main flow and Madison secondary flow) to a discharge point at the north end of the development and for storage area #6 (Unnamed Tributary) to an existing offsite discharge point to the east of the development. Storage Area #1 (compensatory area) is a large storage area that encompasses the majority of the former Painted Hills Golf Course as well as areas to the east of Madison Road. There is no outflow route for this storage area so it is classified as compensatory storage and is allowed to infiltrate through the native soils and into the Spokane Valley Rathdrum Prairie Aquifer. The soils below the storage area include the Spokane Valley Rathdrum Prairie Aquifer as its base followed by layers of course sands that are topped by soils of an alluvial fan or an area of natural deposit from Chester Creek, before the creek was channelized. The floodwaters that enter Storage Area #1 are identified on the July 6, 2010 FIRM Map as the Chester Creek Golf Course Overflow. The Chester Creek Golf Course Overflow originates at a point to the south of Thorpe Road where there was at one time a breach in the man-made channel of Chester Creek. The breach was reportedly from a lack of maintenance and the overgrowth of vegetation in the main channel that blocked the main channel during a storm event. This flow of floodwater enters the storage area from the south at a low point in Thorpe Road through three 15" culverts and, if flow is larger, by overtopping Thorpe Road. Storage Area #6 (triangle pond) is a smaller storage area that is located east of 40th Avenue primarily within a 30-foot-deep gravel pit that was excavated during the early development years of Spokane Valley. Spokane County obtained a drainage easement over the pit in 1983 for storm drainage (flood flow) purposes. The overflow route of storage area #6 is along the south side of 40th Avenue and flows into Storage Area #1 via culverts under Madison Road. The soils below the storage area include the Spokane Valley Rathdrum Prairie Aquifer as its base followed by layers of course sands and gravels that were further exposed by the gravel pit excavation. The Main Flow Across Thorpe Road Concept Design and Process For the concept design the 100-year flood event was used to size facilities. When reviewing the Geotechnical Evaluations, Phase I (December 31, 2013 — Revised August 29, 2016) and Phase II (July 23, 2015) it was evident that there are "valley gravels" or well-draining soils that lead directly to the Spokane Valley Rathdrum Prairie Aquifer under the poor draining soils that cover the site. Therefore, we concluded that if we conducted flood waters into these well-draining soils the flood waters may be treated and discharged. Through extensive review, analysis and confirmation from geotechnical evaluations, it was determined that gravel galleries at the north end of the proposed development represented the optimal location for floodwater infiltration due to the fact that the groundwater depth in this location is much deeper than other locations on the site. See Supplemental Geotechnical Evaluation by lPEC dated April 19, 2016. Proposed Design See Site Element Plan in the attachments. 100 Year Flood Event There is currently a shallow channel to the South of Thorpe Road that conveys the flood water flow from the breach North to Thorpe Road. This 100-year flood event, known as the Golf Course overflow Reach has a peak flow rate of 64 cfs, at the crossing of Thorpe Road, based on the existing FEMA FIS. Since the levee on the east side of Chester Creek immediately downstream of Thorpe Painted Hills Flood Control Development Narrative (Storage Area #1 & #6) Revised March 6, 2018 Page 4 of 6 Road is not certified to protect against the 100-year flood, a peak flow of 91 cfs will be used as the design flow at Thorpe Road instead of the 64 cfs in the effective FIS. The larger 91 cfs flow is more conservative and simulates additional flow that could be contributed to the Golf Course Overflow Reach from the main channel of Chester Creek in the event of a failure of the non-certified levee (without-levee scenario). This provides a conservative design flow which accounts for a potential levee breach or additional overflows that could occur due to the continued mainstream Chester Creek Channel issues, primarily a lack of upstream channel maintenance, which could result in additional overflows. In addition to the overflow from Chester Creek the hillside above Madison Road has a peak design inflow of 15 cfs through the four operational 18" culverts of Madison Road. Therefore, the total peak 100-yr event flow rate used for conveyance and infiltration design for Storage Area #1 is 106 cfs. System Summary On the south side of Thorpe Road, the waters from a 100-year without-levee flood event, the 91 cfs peak flow rate, is proposed to enter a box culvert on the south side of Thorpe Road. The box culvert has a capacity of 216 cfs. From the box culvert the floodwater enters an open channel to a sloped headwall that holds two 48" concrete pipes. Each pipe has a capacity of 77 cfs for a total capacity of 154 cfs. The two 48" pipes extend north from the headwall along Madison Road, with manholes strategically placed to connect to the existing 18" culverts in Madison Road. This connection allows the design flow rate of 15 cfs from the Madison hills to be added to the 91 cfs, for a total design flow rate of 106 cfs. The two 48" pipes end at a vertical headwall where the floodwater splashes out onto a concrete pad and flows across a level spreader into a sloped biofiltration swale. The biofiltration swale cross section has a capacity of 269 cfs. Within the biofiltration swale the suspended solids are stripped out by the tall grasses. At the end of the biofiltration swale is a settling pond that allows the floodwater to settle and rise 1 foot in elevation before flowing over a 20-foot-wide rock weir into the infiltration pond that is 2 feet below the elevation of the rock weir. Within the infiltration pond the floodwater can begin to infiltrate through the pond bottom. When the floodwater in the infiltration pond rises 1 foot in elevation the floodwater will crest over the rim of the 48 drywells and fall into the infiltration trench where the floodwater will then infiltrate into the native soils and enter the Spokane Valley-Rathdrum aquifer. The infiltration trenches have a design capacity of 162 cfs. As demonstrated the flood control system has the capacity to handle the peak 100-yr event without-levee flood design flow rate of 106 cfs with a Factor of Safety of 1.53+/-. The following are descriptions of each design element in more detail. Box Culvert/Open Channel The Golf Course Overflow Reach flows coming from the upstream flow split on Chester Creek is anticipated to approach Thorpe Road as it currently does at the low point in the Thorpe Road profile where there are currently three 15" culverts within the natural drainage way of the Golf Course Overflow Reach. The flow will then enter into a 30-foot-wide by 3-foot-high box culvert under Thorpe Road, replacing the 3 existing culverts. The roadside ditches along Thorpe Road will be regraded to ensure positive flow toward the box culvert. Given the topography of the area, aside from shallow puddles caused by upstream localized depressions, all stormwater will enter into the proposed box culvert. The flow will exit on the north side of Thorpe Road and enter into a concrete open channel with a concrete bottom and vertical concrete walls and then flow to the sloped headwall of the two 48" Pipes. Pipe Mainline At the terminus of the open channel the flow will enter into a two-pipe, parallel, buried pipe system with WSDOT Type II catch basins along the East side of Madison Road. Once inside, the two 48" concrete pipes the flood flow will continue to the north end of the project with an outfall into a bio- Painted Hills Flood Control Development Narrative (Storage Area #1 & #6) Revised March 6, 2018 Page 5 of 6 filtration swale. Each WSDOT Type II catch basin will have a sump for the settling of particles in low flow conditions. These particles or silt can then be vactored out of the manholes as part of the routine maintenance, prior to reaching the bio-filtration swale. Bio-filtration Swale (Channel)/Settling Pond The bio-filtration channel receives the flood water upon discharge from the two 48" concrete pipes. The filtration will be planted with tall dryland grasses. The flow of the floodwater overland through the tall grass provides an initial phase of silt and solid removal before the floodwater flows into a settling pond where additional silt will settle before cresting over a 1' rock weir with 8" minus rock compacted in place. Bio-infiltration pond The crested flood water from the settling pond then flows into an open surface bio-infiltration pond. Within the infiltration pond the suspended particles will continue to decelerate and settle downward to the pond bottom while the clear surface water crests over the rim of the drywells that leads into a gravel gallery system only when the floor dictates. Assuming that the infiltration pond discharges at the rate of 1.6x10'cfs/sf the pond bottom in a non-frozen ground event would discharge (61,000x1.6x10') 9.76 cfs directly to the underlying soils, and not enter the drywells. Therefore, a flow represented by 9.76 cfs is generally consistent with a pre-project flow over Thorpe Road of 0.25' or 3 inches, which has been experienced once during the preparation of this project and documented on February 17, 2017. The gravel gallery system is for the ultimate disposal into the aquifer, its final destination. See Bio-infiltration worksheet in the attachments. Gravel Gallery System Once floodwater flows exceed bottom infill rates it will rise to a depth of one foot and enter the discharge drywells which will evenly distribute the floodwater through gravel galleries by either flowing through the drywell barrels or distributing through the interconnected 12" perforated pipes and galleries along the pond's entire length. The gravel gallery system is based upon a system of 10-foot wide by 10-foot deep infiltration trenches with 3 trenches at 340 feet, a trench at 330 feet, and a trench at 100 feet. the trenches are lined with geo-fabric per WSDOT Std. Spec. 9-33.2(1) and filled with gravel drywell material in conformance with WSDOT Std. Spec. 9-03.12(5). Within the top 3 feet of the infiltration trench runs a 12" perforated pipe at a 0% slope that connects the trench drywells within each trench segment. As treated floodwater crests over the rims of the drywells, the floodwater fills from the bottom up, and equalizes throughout the trench. Once filled the gallery is at its maximum design infiltration rate of 162.64 cfs (see gravel gallery worksheet in the attachments). For analysis the 100-year storm has a peak flow rate of 91 cfs, plus the 15 cfs from the Madison Hills for a total design peak flow rate of 106 cfs. So, with a design outflow rate over 1.5 times greater than the design inflow rate the system will adequately discharge the 100-year flood. This is a conservative measure of protection. Infiltration Rate A full-scale drywell test was performed at the north end of the site. Based on this test we used the design flow rate of 1.8 x 10-3 cfs/sf for design of the gravel galleries in the open space area north of the proposed Cottages residential area. See attached IPEC Geotechnical Report dated June 28, 2016. Maintenance of the pipe, bioswale, road and gravel gallery system is a semi-annual inspection of the gallery through the system drywells looking for a build-up of sediment and debris, and if needed, the removal of the sediment and debris by a vactor truck. Painted Hills Flood Control Development Narrative (Storage Area #1 & #6) Revised March 6, 2018 Page 6 of 6 Secondary Protection As a secondary measure of protection, a detention facility is proposed at the south end of the project in the park area. A 176,181-sf area located in the park area has been lowered 3 feet +/- from the existing ground surface. This area will be covered with grass turf and will function as park open space, with gentle 3:1 side slopes for easy access. If for whatever reason an emergency situation exceeds the capacity of the pipe headwall or if the 48" concrete pipe inlets are blocked by debris, floodwater is intended to crest over the open channel wall and flow into the park as a temporary containment measure. The detention facility has an outlet located in the NE Corner. The outlet is a catch basin with a rim elevation placed 1 foot above the bottom of the park. The catch basin has an 18" pipe that connects into the western 48" concrete Pipe that runs along Madison Road. Below the rim of the catch basin the detention facility has a holding capacity of 178,699 cf or 4.10-acre feet, at a final grade of 5 ft depth the detention facility has an ultimate holding capacity of 943,866 cf or 21.67- acre feet. While the detention facility is not the ultimate disposal point for flood water the detention facility provides a secondary containment that will detain the floodwater and drain flood water back into the flood control system without risking a flood of the subdivision streets. Project Site Fill and Flood Protection Measures The project site is protected from the main channel of Chester Creek by the existing levee type fill of property along the existing Chester Creek channel and along Dishman-Mica Road. As was originally proposed and noted the project was going to be a levy type flood control project. However, it has since been modified to strictly a fill project where all future building pads will be placed 1.0 feet above the Base Flood Elevation (BFE). The new fill elevation is proposed to be placed 1 foot or more above the Chester Creek Base Flood Elevation (BFE) and then be graded out across the site toward Madison Road. All building pads will be placed above the BFE and certified to FEMA during the development. The project proposes to place 328,289 +/- cy of compacted fill on site to achieve this goal, Therefore, it is incumbent upon the reader to understand that the grading plan of the project site will be to raise the overall site surface. So that all residential building pads will be at least 1.0 foot above the BFE and will therefore always be out of the floodplain, even if the discharge measures experience some catastrophic failure of infiltration during a flood event. Design Elements Box Culvert Open Channel Pipes Bioswale Settling Pond Rock Weir Pond Drywell Infil. Trench Width/Area 28' 28' 48" 6' 7,172 sf 2' 61,004 sf 48" 10 Length 45' 18' *2,629' 334' - 20' - - *1,450 Slope 0.5% 1.0% 0.26% 1.0% 0.0% 0.0% 0.0% - 0.0% Depth 3' 6' - 6' 6' 5' 7' 18' 10' Elev: inThtna 2007.58 2007.36 2007.18 2000.04 1996.80 1997.80 1995.80 1996.80 1978.8 Elev: Out 2007.36 2007.18 2000.24 1996.80 - - - *Indicates a total The Secondary Flow Across Madison Road: The flow across Madison Road is divided into 5 basins from the heights above and to the east of Madison Road that correspond to the 5 culverts that are placed under Madison Road. The most northerly culvert does not have an outlet on the west side of Madison Road. Therefore, the floodwater that should enter this culvert goes to the south to the culvert at Sta 30+42. The floodwaters on the east side of Madison Rd distribute along the east side of Madison and appear to be separated into the four culverts that cross Madison Road at Stations (S to N) 13+22, 20+44, 24+41 and 30+42. As the development proposes to Painted Hills Flood Control Development Narrative (Storage Area #1 & #6) Revised March 6, 2018 Page 7 of 6 widen Madison Road on the west side, the 4 culverts will be replaced and extended. Since the proposed inverts of the extended culverts will fall below the proposed grade of the roadside swales, the culverts will connect into the East 48" pipe. The storm water along the west side of Madison Road will be collected in roadside swales where it will receive treatment. The swales will have catch basins with the rim set 6" above the swale bottom. Any excess treated flow that does not infiltrate and exceeds a 6" depth will enter the catch basins. The catch basins will be connected to the East 48" mainline pipe. West Consultants provided the following 100-year storm flows for each culvert during the 100-year storm. We are using these flows to size and design floodwater facilities. STA. 100 Year Storm Flow (cfs) 13+22 4 20+44 1 24+41 1 30+42 2 38+98 7 Total 15 Any floodwater generated west of the triangle pond along E 40th Avenue flows to the west. Then at Madison Road it flows south between the road and the easterly hillside. These flows will be intercepted with the replacement culverts installed at Stations 13+22 through 30+42 that are connected at manholes into the east 48" pipe. North Pond Mounding Analysis On August 22❑d 2017 IPEC completed a mounding analysis of the infiltration galleries on the north side of the project. In 2017 the design was not a pond with galleries below, as it is today but simply a series of infiltration galleries that are smaller than the current design. The mounding analysis utilized the established infiltration rate and applied the rate to smaller infiltration area of the time. The result was a 9.01-foot-high mound at the center of the facility and a 6-inch-high mound at the edge of the facility. It was then concluded that the infiltration of stormwater would not have significant down gradient impacts. With the current larger pond and infiltration gallery it is anticipated that the mound would be reduced in height and the conclusion would be the same. Painted Hills Flood Control Development Narrative (Storage Area #1 & #6) Revised March 6, 2018 Page 8 of 6 The Secondary Flow From Highway 27 (Spokane County) Proposed Design The existing and documented 16 cfs flood flow from Highway 27 (Unnamed Tributary) is currently conveyed via a 36" culvert (limiting factor) that empties into a ditch that flows West across the Gustin property (Parcel No. 45344.9108). The stormwater flows through the ditch and into the existing County borrow pit within the triangular parcel located northeast of E 40t11 Avenue (Parcel No. 45343.9052). The existing ditch has been maintained over the years by the property owner (Gustin) to ensure that whatever floodwater comes out of the culvert under Highway 27 will be conveyed to the existing borrow pit. With this or a separate project the ditch will be replaced with a 36" pipe that extends from Highway 27 to the proposed infiltration (triangle) pond bottom in barrow pit. With the pipe there is no potential for floodwater to flow in the natural drainage way to the West. The existing pond is anticipated to be regraded with 18 drywells being installed. Design Elements: Proposed Pond 17,060 sf @ El: 1990.00; 35,812 sf @ El. 1995.00; 84,416 sf @ El. 2000.00 Drywell spacing 30', total drywell outflow 18.0 cfs, negates pond bottom, frozen ground flow Maintenance Access Road: 6" gravel, max grade 10%, min. radius 35' Fenced with gate Infiltration Pond WCE proposes to improve the outflow of the (triangle pond) borrow pit by regrading and expanding the lowest bottom area of the borrow pit and installing 18 double depth drywells into the bottom of the internal pond. The drywells will provide outflow during a frozen ground condition. Each double depth drywell will provide a design outflow of 1.0 cfs for a total of 18 cfs per the recommendations in the Geotechnical Evaluation by IPEC dated October 14, 2014. If you have any questions or comments in regard to this letter please feel free to contact us at (509) 893-2617. Sincerely, WHIPPLE C SULTING ENGINEERS, INC. 4,2:462 ."vISTEite9 Todd R. Whii71:ie-, PE TRW/bng Encl: Attachments CC: File ATTACHEMENTS Bibliography Site Element Plan (Sheet C1.3) 100 Year Flood Event Flows Thorpe Road Crossing Madison Hills Flow to Culverts Gustin Pipe Flow to Culverts System Capacity Box Culvert Madison Pipe Bioswale Trapezoidal Channel Storage and Discharge Pond Summary Worksheet Gravel Gallery Worksheet — North Bio-filtration Channel Worksheet Geotechnical Reports BIBLIOGRAPHY 1) Dawes, Larry. February 28, 2019. Biological Evaluation, Critical area Report, and Habitat Management Plan for the Painted Hills PRD. Biology Soil & Water, Inc., Spokane Valley, WA. 13-14. PAINTED HILLS PRD BIOLOGICAL EVALUATION, CRITICAL AREAS REPORT, AND HABITAT MANAGEMENT PLAN Spokane County Tax Parcels #45336.9191 and 44041.9144 February 28, 2019 -,••••& an,.1 .4... I , t•••.. Biology Soil & Water, inc BIOLOGICAL EVALUATION, CRITICAL AREAS REPORT, AND HABITAT MANAGEMENT PLAN for the PAINTED HILLS PRD Spokane County Tax Parcels #45336.9191 and 44041.9144 February 28, 2019 Retained by NM Black Contact Person: Bryan Walker 107 S. Howard St., #500 Spokane, WA 99201 509.622.3593 (m) 509.623.1000 (o) bwalker@naiblack.com Investigated by Biology Soil & Water, Inc. Contact Person: Larry Dawes, Principal Biologist 3102 N. Girard Road Spokane Valley, WA 99212-1529 Phone 509-327-2684 Email: bswinc@icehouse.net LIST OF CONTACTS Bryan Walker 107 S. Howard St., #500 Spokane, WA 99201 509.622.3593 (m) 509.623.1000 (o) bwalker@naiblack.com Todd Whipple Whipple Consulting Engineers 21 South Pines RD Spokane Valley, WA 99206 (509) 893-2617 (toddw@whipplece.com) Larry Dawes Biology Soil & Water, Inc 3102 N. Girard Road Spokane Valley, WA 99212 Phone 509-327-2684 bswinc@icehouse.net 38 BIOLOGICAL EVALUATION, CRITICAL AREAS REPORT AND HABITAT MANAGEMENT PLAN for the PAINTED HILLS PRD Spokane County Tax Parcels #45336.9191 and 44041.9144 July 20, 2015 (Revised August 30, 2016, and February 2019) 1.0: Introduction Biology Soil & Water, Inc. (BSW) was retained by Black Realty to complete a Biological Evaluation (BE) for the proposed Painted Hills Planned Residential Development (PRD) located in the City of Spokane Valley, WA. This BE also includes all of the Critical Areas Report and Habitat Management Plan (HMP) elements required by the City of Spokane Valley Municipal Code, Section 21.40 (SVMC 21.40). South Dishman Mica Road defines the west boundary of the site, E. Thorpe Road defines the south boundary of the property, S. Madison Road defines the East boundary, and developed private property defines the north property boundary (Figures 1-3). The Painted Hills Golf Course formerly occupied this location. The former club house was renovated to expand the existing restaurant and the remainder of the site will become residential development and open space. The subject property is comprised of seven separate tax parcels totaling 99.5 acres (+/-) where 580 residential units are proposed, and a 10+ acre parcel on the south end of the site that will be designated as a wildlife travel corridor. The Action Area was defined as a half mile radius of the 99+ acre Project Area so the site investigation would characterize adjacent areas where listed species could live or be impacted by the project. This assessment addresses all Critical Areas and listed Priority Habitat and Species including Threatened, Endangered, Proposed, and Candidate Species in the Project Area. The USFWS and NMFS species lists were accessed on their websites on 4/21/2015 and updated August 29, 2016 and January 29, 2019. No NMFS species are listed for the vicinity. The USF&W list indicated the potential presence of the species and critical habitat(s) shown in Table 1 (and in Appendix 1). Table 1. USFWS listed species and critical habitats potentially present in the vicinity of Species ESU/DPS Federal Status Designated Critical Habitat Bull trout Salvelinus confluentus Columbia River DP S Threatened Yes Water howellia, Howellia aquatilis Threatened No Spalding's silene, Silene spaldingii Threatened No Canada Lynx, Lynx canadensis Threatened No Yellow-billed cuckoo, Coccyzus americanus, Threatened No The undersigned investigated the Project and Action Areas on March 1, March 29, and April 19, 2015. The site conditions have not changed since the investigation in 2015. The conclusions of this plan are based on an evaluation of habitat and species data for Spokane County compiled by State and Federal jurisdictions, an evaluation of construction plans and specifications for the project, a literature review, and field investigations by the author of this report. The project will have no effect on Bull Trout or proposed Bull Trout Critical Habitat. The project will not result in the destruction or adverse modification of potential, designated or proposed Critical Habitat or Essential Fish Habitat for any fish species. The project will have no 1 DELORME Topo USAF 8 Variant to !Bland Nttnsimo(- .--RIchmetidL-'13w.riabY 01016'isok • l'' — 'Langley ---" `. . Surrey : . -... czi 15In lu d -.. lkr ieut41ook.11,,,,,,,,....741).-b9-t.sk-..."1.—.....tr•-•,•,..----..----- Cowlchan tRolz Lace 11 1q-C, ,e044 18'111gtr • k Selais "■.. 11.7 .t, L it'l Vitet;iala": ''l . ...e• d .• ' a • • „,...,.......S;:cAPtitor de carca .." 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SPOKANE VALLEY,WA SHEET P0.11 JON NUME•H 13-1166 effect on the threatened species Water howellia, Spalding's silene, Canada lynx, or the Yellow- billed cuckoo. There will be no significant adverse effect on any listed Species of Concern. The site plan includes a 10+ acre wildlife travel corridor for deer and elk and over 30 acres of open space. The Project Area does not meet any of the Department of Natural Resources (DNR) criteria for High Quality Terrestrial Habitat. Washington Department of Fish and Wildlife (WDF&W) maps (Appendix 2: Critical Areas Maps) indicate the subject property falls within an Elk polygon (WDF&W Priority Habitat). A 10+ acre wildlife travel corridor is proposed along the entire south end of the project and the corridor will be enhanced with vegetative plantings to accommodate animals traveling through the area. Chester Creek and its associated 100-foot buffer bisects the SW corner of the property. Buffer Width Averaging is proposed to compensate for the encroachment of two lots and foot paths in the riparian buffer. The impact mitigation also includes riparian buffer enhancement. The existing buffer is almost totally devoid of woody vegetation because it was previously a driving range and/or maintained golf course fairway. An evaluation of streams and wetlands is included in this report. 2.0: Methods of Investigation The north parcel of the Project Area is located in Sec. 33, T25N, R44E and the south parcel is located in Sec. 4, T24N, R44E of Spokane County, WA (Figures 1-3). Biology Soil & Water, Inc. (BSW) investigated the property on March 1 and 29, and April 19, 2015 for wetlands, riparian habitat, and species protected under the Federal, State, and local regulations. The undersigned is familiar with the soils, vegetation, and hydrologic characteristics of this property from previous investigations of adjacent properties in the immediate vicinity and throughout the drainage basin. 3.0: Description of the Action and Project Areas Spokane is located in a valley at the westmost extent of the Rocky Mountains. From the north side of the Spokane River valley, the Selkirk Mountains extend north into Canada. On the south side of the Spokane River valley, a forested finger of the Bitterroot Mountains extends east from Lake Coeur d'Alene to Dishman Hills. The subject property is located in the Chester Creek valley with forested foothills on the east and west sides of the valley. The Painted Hills PRD is surrounded primarily by residential development with varying degrees of housing density, a few small undeveloped tracts of agricultural land in the Chester Creek valley, and forested land with varying densities of residential development (Figure 4). 3.1: Description of the Action Area For purposes of describing habitat in the surrounding area, the Action Area is defined as a half mile radius of the project area. Habitat types in the Action Area would be described as a mosaic of urban developed, fragments of conifer forest, and small tract agriculture. From the north property line, dense residential development extends north into the City. A church and residential development border the painted Hills PRD at the NW corner. Horizon Middle School is located NE of the site. From the east property line (S. Madison Rd) hay fields and pasture extend 250-500 feet toward the toe of the surrounding forested slopes. Sparse residential extends east up the forested hillsides. Commercial and single-family residential development extends south from Thorpe Road except for the Chester Creek drainage and associated flood plain that is 5 02, ' - ;I'. ...L.. - • • 14-r. iy 1' _ t3 4 4 • , 015 Google 4e. ' X17 .. Google earth Go sle earth miles km mainly forested and small tract agriculture. Undeveloped forested hillsides extend about 1200 feet east to the densely developed Ponderosa neighborhood. A mixture of commercial and residential land uses extend NW along Dishman-Mica Road. Land uses in the Action Area are a mosaic of dense residential development on former agricultural land, remaining undeveloped small tracts of agricultural land, and forested land with varying densities of residential development. Large mammals that are willing to cross highways and residential developments interspersed with open farm land will find connectivity to a few hundred acres of wooded and sparsely populated foothills extending south and west from the Painted Hills PRD site to Dishman Hills. 3.2: Description of the Project Area The 99+ acre Painted Hills PRD property was formerly a golf course. Black Realty Inc. bought the property in a trustees auction in the fall of 2013 after the owners filed for bankruptcy in 2012. Except for cart paths, sand traps, and man-made water hazards, the entire property was planted in non-native turf grasses with sparse conifer and deciduous trees lining some of the fairways. The turf grass was maintained by treatment with herbicides and regular mowing of the greens, fairways and rough. These practices virtually eliminated the native herbaceous plant community. Since golf course maintenance ceased, noxious weeds have invaded the site. Honey willows were planted inside the Ordinary High Water Mark (OHWM) of Chester Creek whose channel was historically dredged and maintained for flood control. The banks of the channel are covered with Reed canarygrass. Outside the OHWM of the stream channel where the vegetation was not mowed or maintained, the vegetative community is dominated by Canarygrass. Teasel, tansy, thistle, wormwood, and lettuce are also well represented. 3.3: Comparison of three Development Alternatives A State Environmental Policy Act (SEPA) Environmental Impact Statement (EIS) is being prepared for the project. The EIS provides a detailed analysis of three alternatives. Alternative #1 proposed no development. Alternative #2, the preferred development scenario, was for the Planned Residential Development discussed in this report. Alternative #3 was for a standard Residential Subdivision under the current zoning without PRD requirements and density. A detailed comparison of the three alternatives is provided later in this report. 4.0: Project Risk Assessment and Impacts Listed threatened and endangered species identified by jurisdictions for potential occurrence in Spokane County include the Yellow-billed Cuckoo (Coccyzus americanus), Canada Lynx (Lynx canadensis), Bull trout (Salvelinus confluentus), Water howellia (Howellia aquatilis) and Spalding's silene (Silene spaldingii). A BSW field investigation determined that the project would have NO EFFECT on any of the above listed species. 4.1: Yellow-billed Cuckoo (Coccyzus americanus), Federal Status: Threatened The yellow-billed cuckoo was formerly a very rare summer visitor to western Washington, especially in the Puget Sound area (Roberson 1980). Jewitt et al. (1953) described the former breeding range in Washington as ranging north to Bellingham, east to Ellensburg, south to Vancouver, and west to Grays Harbor. There are only two published records of yellow- billed cuckoo in eastern Washington. Yellowbilled cuckoos were detected on July 21, 1956, 20 7 miles north of Grand Coulee Dam in Okanogan County (Weber and Larrison 1977) and in June 1978 at George, Grant County (Roberson 1980). The March and April investigations occurred before the Yellow-billed cuckoo would have migrated into the Spokane County area if it seasonally utilized the area for breeding or nesting. The investigation for the Yellow-billed cuckoo focused on specific habitat requirements of that species. Cuckoos prefer to nest in areas with at least 10 hectares (ha) (25 acres) of contiguous (riparian) woodland (Laymon 1998). The typical patch size is 20 ha (50 acres) or greater, and the likelihood of occupancy increases dramatically with increasing patch size, but they have been found breeding in patch sizes as small as 4 ha (10 acres) along the Colorado River in southern California (Johnson, Matthew J., 2007). Yellow-billed cuckoo's nest in undisturbed stands of cottonwood/willow galleries greater than 10 acres in total area and greater than 100 meters wide along waterways. The project area does not contain, and is not in close proximity to, adequate habitat patches for that species. The largest habitat patch consisting of species utilized by the yellow- billed cuckoo is less than one tenth of the minimum patch size utilized by this reclusive species. The yellow-billed cuckoo is known not to utilize any habitat with characteristics of those found along Chester Creek adjacent to this project. This project will not impact yellow-billed cuckoo populations or habitat components. There is no suitable habitat for the yellow billed cuckoo in the vicinity of this project. The project will have NO EFFECT on the yellow-billed cuckoo. 4.2: Bull Trout (Salvelinus confluentus) Threatened The U.S. Fish and Wildlife Service (USF&WS) lists the Columbia River population of bull trout as threatened. Small pockets of bull trout are present in isolated habitat fragments in the main stem and tributaries of the Columbia River. One isolated fragment of the Columbia River segment includes Coeur d'Alene Lake, its tributaries in the drainage basin, and the Spokane River. Bull trout populations have been identified in Coeur d'Alene Lake and three tributaries in its sub-basin, but no bull trout populations are known to occur presently, or have been noted historically, in the Spokane River downstream from the Post Falls Hydroelectric Dam (PBTTAT, 1998). The Post Falls dam stops the migration of fish out of the Coeur d'Alene basin downstream into the Spokane River. Waterfalls and dams prevent the upstream and downstream migration of bull trout into the segment of the Spokane River and its tributaries in the vicinity of the project area. No dam on the Spokane River has a fish passage facility and all dams create fish barriers for upstream and downstream migration. EPA fact sheets for 1999 NPDES permits for wastewater treatment plants discharging to the Spokane River state that bull trout cannot get past the Post Falls Dam (EPA 2008). There is no known population of bull trout in the Spokane River downstream of the Post Falls dam (FERC 2006). The USFWS does not include the Spokane River and its tributaries located downstream from the Post Falls dam in bull trout recovery planning efforts (Federal Register / Vol. 75, No. 200 / Monday, October 18, 2010). The project will have No Effect on Bull Trout. Bull Trout Critical Habitat Activities that may adversely modify critical habitat include those that alter the primary constituent elements to an extent that the value of critical habitat for both the survival and recovery of the bull trout is appreciably reduced. The proposed project will not destroy or adversely modify critical habitat by altering primary constituent elements. The value of critical 8 habitat for both the survival and recovery of the bull trout will not be reduced as a result of this project. The project will not alter the minimum flow or natural flow regime of the subject stream, alter any segment of the stream, riparian vegetation, or any chemical parameters so as to reduce water quality, alter channel morphology or create instream barriers to bull trout movement. No decrease in water quantity will occur because of the project. The project will cause no significant and detrimental alterations to water quality and will have NO EFFECT on proposed Bull Trout Critical Habitat. 4.3: Spalding's catchfly (Silene spaldingil), Federal Status: Threatened The range of Spalding's silene (Silene spaldingii) includes eastern Washington, northeast Oregon, Idaho, and western Montana. Spalding's silene occurs primarily in open grasslands with minor shrub and/or (occasionally) scattered conifer components. Spalding's silene is found most commonly in Idaho fescue/snowberry associations at elevations of 1900-3050 feet. These sites are typically dominated by Idaho fescue and have sparse cover of snowberry where the total vegetative cover is greater than 100%. Some of these sites occur in a mosaic of grassland and ponderosa pine forest. Spalding's silene populations have been found on all aspects, although there seems to be a preference for slopes that face north. On drier sites, the species can be found on the bluebunch wheatgrass/Idaho fescue association. Spalding's silene can occupy habitats that vary from sagebrush plains to mountain ridges. Spalding's silene generally occurs in native grasslands that are in reasonably good ecological condition, although populations have persisted in areas that have had moderate grazing pressure. Populations tend to be quite small and are currently quite fragmented, raising questions about their long-term viability. Fire may have historically played a role in maintaining habitat particularly in sites that are interspersed with ponderosa pine forest. Much of the historically suitable habitat has been lost through conversion or degradation. The timing of the site investigation did not coincide with the flowering of listed plant species. The project biologist is a qualified botanist and wetland professional that routinely completes site investigations during all seasons when snow does not cover vegetation. Site investigations often occur when salient plant flowering parts are senescent or may not be sufficiently preserved to allow taxonomic identification beyond genus to the species level. Twenty years of experience in plant identification during all life history and seasonal growth habits has equipped the project biologist to conduct accurate plant identifications and wetland investigations in accordance with best available science and consistent with the accepted professional practices for the conditions at the time the work was performed. Individual plants exhibit essential identification characteristics unique to their genera, but display sufficient variation so it is possible to categorize and differentiate each species within a genus using taxonomic keys. During plant senescence, individual characteristics often become blurred making it difficult or impossible for a botanist to differentiate among species within the genus. The sepals of the genus Silene form a bulbous calyx that is easily recognized and sufficient to identify the plant to genus. The Threatened species Silene spaldingii overlaps in range and is somewhat similar in appearance with some other species in the genus. The field biologist is familiar with the species and has observed it at other locations. During the field investigation, the Silene genus was not identified in the Action or Project Areas. Previous years of cultivation, followed by the planting of turf grasses, years of mowing, and herbicide applications is sufficient grounds for discounting effects on Spalding's silene when considered alone. No populations of Spalding's silene were identified in the Project Area during 9 the field investigation. The project will have NO EFFECT on Spalding's Silene and will not result in the destruction or adverse modification of potential, designated or proposed Spalding's silene Critical Habitat. 4.4: Water howellia (Howellia aquatilis) Howellia is found in seasonal wetlands, ponds and lakes because its seeds do not germinate under water. Since seeds germinate in the fall and over-winter as seedlings Howellia requires a dry autumn followed by a wet spring in order to establish for the year. In addition to seasonally fluctuating ponds, Howellia requires fertile, highly organic soils, which are generally maintained by deciduous trees surrounding the ponds. Research indicates that Howellia does not form a persistent seed bank, making this annual especially dependent on year to year reproductive success in order to persist. No Howellia was observed in the Project Area. Howellia is found in seasonal wetlands, ponds and lakes. No Howellia habitat occurs in the Project Area. The project will have NO EFFECT on the Howellia aquatilis species and will not result in the destruction or adverse modification of potential, designated or proposed Howellia Critical Habitat. 4.5: Canada lynx (Lynx canadensis) Federal Status: Threatened Lynx prefer dense coniferous forest with sapling/pole thickets, rock outcrops, and wetlands at elevations of around 4000' to 4500'. The elevation of the Action Area is around 2010-2015 feet. Denning usually occurs in mature old growth stands with lots of deadfall. These forested stands do not occur in the Action Area. Lynx prefer snowshoe hare habitat, as they are dependent on snowshoe hare as a staple food item. Snowshoe hare prefers dense lodgepole stands that do not occur in the Project or Action Areas. BSW did not find any evidence of Canada lynx in the low elevations associated with the Project Area. The project will have NO EFFECT on the Canada lynx or Canada lynx habitat. The Canada lynx does not appear on the 1/29/2019 official USFW species list for the site. 4.6: Species of Concern The site was also investigated for the presence of species from the Species of Concern list for Spokane County published by the U.S. Fish and Wildlife Service. Most of these species are also included in the WDF&W list of priority species that was adopted by the City of Spokane Valley. Each species is listed below, followed by an evaluation of available habitat, observed habitat utilization, and potential project effects. Bald eagle (Haliaeetus leucocephalus) The Bald eagle is listed as a State Sensitive species. Eagles do not nest near the Project Area. Human activity associated with major roads and urban development are limiting factors for Bald eagles in the Action Area. At any location in Spokane County road kill can provide food for transient opportunist eagles. However, Bald eagles do not routinely forage in the Action Area and no nest sites were observed by BSW within one-half mile of the Project Area. BSW concludes that noise and human activity during construction will not impact eagle nesting as no nests were identified in the Action Area. Perching and foraging opportunities occur on the stream bank and eagles could utilize the stream corridor. The project will have NO EFFECT on the Bald eagle. 10 Western Burrowing Owl (Athene cunicularia) No historical observation in the vicinity. No individuals, nests, or sign observed during the site survey. No Effect from project. California floater (Anodonta californiensis) freshwater mussel. No Effect from project. Ferruginous hawk (Buteo regalis ) nests on rocky ledge or high ground vantage on prairie. No Effect from project. Giant Columbia spire snail (Fluminicola columbiana) cold, unpolluted, medium to large streams. No Effect from project. Loggerhead shrike (Lanius ludovicianus) A robin sized gray, black, and white bird of open areas. Community types not dominated by shrubs, such as grasslands and riparian areas, are not used. Loggerhead Shrikes prefer nesting in big sagebrush and antelope bitterbrush, and avoid spiny hopsage, rabbitbrush, and green rabbitbrush (Chrysothamnus viscidiflorus). Nest shrubs are taller, closer to an edge, and contain denser cover and fewer main stems than unoccupied shrubs. Roost shrubs are large, dense live shrubs, whereas tall, dead shrubs that provide good visibility are used for perching. No Effect from project. Longeared myotis (Myotis evotis) Roosts are sometimes found in crevices in small basalt rock formations. Compared to random plots, roosts are in more open, rocky habitats, closer to the edge of forest stands, and relatively distant from sources of permanent water. Often roost in Ponderosa pine trees >30 cm in diameter and >12 m high. Less use of grasslands and closed pine than expected. No significant effect if present in vicinity. Northern goshawk (Accipiter gentilis) goshawks select relatively closed-canopy conifferous/boreal forest habitat for nesting - No significant effect. Olivesided flycatcher (Contopus cooperi) found in boreal and western coniferous forests - No Effect Pallid Townsend's bigeared bat (Corynorhinus townsendli pallescens) Eastside mixed conifer forest, shrub-steppe, and riparian-wetlands. In Washington, old buildings, silos, concrete bunkers, barns, caves, and mines are common roost structures. No effect on roosting or hibernicula Peregrine falcon (Falco peregrinus) Two subspecies of peregrine falcons (Falco peregrinus ) occur in Washington state at present, (F. p. pealei and F. p. anatum ). Peale's peregrine falcon is a coastal subspecies so our concern in Spokane County is with F. p. anatum (Continental peregrine falcon). DDT exposure totally eliminated this subspecies from former breeding sites in eastern Washington. Following a ban on the use of DDT, captive-reared young birds have been released at several sites in Spokane County in an attempt to augment natural reintroductions by wild birds. There is no potential for degradation or loss of critical habitat for peregrine falcons in the project area. Peregrine falcons nest on cliffs or even man-made structures such as buildings or bridges that do not occur in the project area so no action is required to protect nest sites from human disturbance. The primary method used to reintroduce falcons to the wild is called "hacking". WDF&W does not currently use any hack sites in the vicinity. No significant effect Redband trout (Oncorhynchus mykiss) No Effect from project. Sagebrush lizard (Sceloporus graciosus) No Effect from project. Westslope cutthroat trout (Oncorhynchus clarki lewisi) No Effect from project. Palouse goldenweed (Haplopappus liatriformis) palouse, not in our area No Effect 4.7: WDF&W Priority Species Deer, Elk, and Gray Wolf Impacts to the WDF&W Priority Species White-tailed deer and Elk will be minimized by protecting a travel corridor through the site. The subject property is not mapped as White-tailed 11 deer priority habitat. Wooded lands to the east and south are mapped as priority white-tailed deer habitat. However, deer utilize the site as they do all undeveloped parcels in the area. The site falls within the northern extent of the mapped Elk Habitat polygon in the Spokane Valley. The site does not provide cover or refugia required by elk and is not elk habitat, but Elk moving through the general area between Mica Peak and Dishman Hills could potentially cross the subject property on east/west treks. The developer will protect and enhance an east/west 10+ acre deer and elk travel corridor across the property. Woody vegetative plantings prescribed for the corridor will provide some habitat value and protective cover where none currently exists. Deer will continue to use the area set aside as a travel corridor. The site is also mapped as Gray wolf habitat. It is possible that wolves could travel through the area in search of prey. There are deer and abundant small (domesticated) mammals available in this residential area so their presence would not be well received in the surrounding neighborhoods. Wolves could also utilize the 10+ acre travel corridor for safe east/west passage through the property. On May 5, 2011, wolves were federally delisted in the eastern one-third of Washington State. 4.8: Wetlands Wetland Inventory Maps of the site show two wetlands on the property (Appendix 2). Both of the wetlands are shown to occur on the west side of Chester Creek. BSW investigated the mapped wetlands on March 1, 2015. In each mapped wetland, BSW dug a test hole on top of the creek bank in close proximity to the Chester Creek OHWM. On March 1, neither of the test holes had saturated soils in the top 16 inches of the soil profile. In Test Hole #1 the water table was at 21 inches and saturation occurred at 16 inches. In Test Hole 2, there was no saturation in the top 24 inches of the soil profile. The test holes were inspected again on March 29th and the water level in test holes was lower than on March 1st. This result was expected due to the landscape position of the mapped wetlands. The year to date precipitation for Spokane was fluctuating between slightly above normal for the year to slightly below normal for the year to date making this year to date average in precipitation. Wetland hydrology should have been present in what was a normal year at the time of the investigation if the subject areas were wetlands. The argument that Spokane was below normal for the hydrologic year is also not valid for this drainage basin because it has a low elevation and runoff comes earlier in the year than many other drainages as will be explained in detail below. The wetland hydrologic criteria was not met in either test hole at the start of the growing season when the water table should have been at its annual high. Stream high water conditions consistent with a high water table does not typically occur during the growing season on Chester Creek. Seasonal high water occurs in the winter during rain on snow and frozen ground conditions. During the growing season, wetland conditions do not occur outside of the stream OHWM where the National Wetland Inventory Map indicates the wetlands occur. David Moore, DOE, investigated the site on June 8, 2016 and concurred with that finding in the field and by phone after the site visit. The hydrologic studies referenced in this report all conclude that Chester Creek is not influenced by a high water table so it loses water to the underlying sands and gravels. This prevents wetland conditions from occurring outside the area of flowing water in the channel. The author of this report concurs with those conclusions based on 20+ years of personal 12 observations of hydrologic conditions and numerous wetland investigations in the Chester Creek drainage basin. Most streams occur in the lowest elevational contour of a drainage basin where bedrock, or some restricting layer, prohibits the infiltration of water and causes a seasonal high water table. Under those physical conditions, the water table influences, or contributes to the stream through the winter and spring portions of the hydrologic year. The key feature to wetland occurrence in riparian zones is a high water table that generally correlates to the surface elevation of the stream. Wetland conditions form when the water table comes in close proximity to the soil surface during the growing season. The water level in the stream generally corresponds to the top of the water table in the surrounding basin. During the growing season, evapotranspiration lowers the water table at the same time annual precipitation decreases. When the water table falls, isolated depressions remain full of water until the water table drops allowing the depressional wetlands to dry out. When these depressions remain inundated or saturated for sufficient duration, DOE considers them to be wetlands within the stream channel. At some point the water table falls below the bottom of the stream and no longer contributes to base flow in the stream. The above scenario does not occur in Chester Creek. Chester Creek loses water to the underlying sands and gravels all year long. Chester Creek flood events occur during the winter when heavy rains on frozen ground and/or snow prevent infiltration of stormwater in the contributing basin. Flood events do not occur during the growing season. The extent and duration of occasional flood events depends on how long the above normal precipitation continues and how far downstream the flooding spreads before infiltration exceeds hydrologic input. The frequency, duration, and extent of flooding have been attenuated by flood control measures thoughtfully implemented downstream. The flood control measures proposed with this project are a continuation of that process. In summary, Chester Creek is not influenced by a high water table that creates wetlands. Chester Creek loses water to the underlying sands and gravels so wetlands do not occur outside of the channel of flowing water. The test holes evaluated with a shovel by BSW in 2015 and again in 2016 support that conclusion. That conclusion is backed by 20+ years of personal experience in the basin, previous hydrologic studies of the basin, Bore Hole Logs taken within the area of interest on Chester Creek, Bore Hole Logs throughout the Painted Hills project area, well logs of proximate properties, and the Geotechnical and Hydrologic Analysis of the same Bore Hole Logs. No wetlands occur adjacent to Chester Creek because is not influenced by a high water table. This conclusion is supported by the Geotechnical Evaluation of the area. The author of the Geotechnical Evaluation report reached the same conclusion as BSW, that Chester Creek loses water to the underlying well drained sands and gravels all year long preventing wetlands from forming. 4.8.1: Chester Creek Flood Frequency A hydrologic and hydraulic analysis for Chester Creek was completed by Michael Baker Jr., Inc. and approved by Spokane County in a letter to the Federal Emergency Management Agency dated August 6, 1990. There are no long-term gage records for Chester Creek. The limited gage measurements on Chester Creek were collected near the Dishman-Mica Road crossing of Chester Creek from December 1994 through March 1995 and November 1995 through February 1996 when no flood events occurred. In February 2006, the hydraulic analysis for Chester Creek was revised by West Consultants, Inc. under a FEMA contract. The analysis 13 established flood magnitude-frequency estimates for the watercourse. A steady flow model has been developed for Chester Creek. The reports conclude that spring floods in the upper Spokane River basin are due to snowmelt runoff from high elevation watersheds. Such floods are of less significance on Chester Creek because the lower elevation of the watershed limits the size of the snowpack so spring runoff occurs about a month earlier and at more gradual rates than on the Spokane River. Nearly all maximum annual flood peaks on Chester Creek occur during the winter. Warm winds and rain can melt the snow rapidly. The May 1948 flood on Hangman Creek was a non-typical flood caused by a heavy snowpack, a late, cold spring, and heavy rains during the critical snow melting period. All other maximum annual flood peaks on Hangman Creek occurred during the winter. When winter rain causes snowmelt on frozen soil conditions, short-duration, intense runoff generates a flood peak during winter storms. During the more extreme events, Chester Creek runs over its banks filling depressions in the flood zone. The duration of flooding is generally between 100 hours and 1000 hours, or between four days and forty days with smaller events occurring with greater frequency than large events. Hydric soils form under saturated soil conditions. Wetlands have to exhibit saturated soils during the growing season, but those conditions seldom occur outside of the stream channel on Chester Creek because flooding usually happens in the winter. Floods are typically of a small magnitude so when over bank flow fills depressions outside of the channel, the water has usually infiltrated before the growing season begins. The subject areas may have been exposed to more frequent flooding in the past, but good planning and flood control measures designed to minimize flooding have moderated those historical flood events to some degree. Chester Creek does not follow the same hydrograph as snowmelt dominated systems. 4.8.2: Flood Protection Measures Channel geometry for Chester Creek were developed from surveys conducted in March 2003. Overbank geometry were developed from topography developed by TerraPoint (2003). Flood plain boundaries for Chester Creek and Unnamed Tributary to Chester Creek were delineated using 2-foot contour interval maps developed by TerraPoint from LiDAR data. Previously, a watershed plan for Chester Creek was designed with management recommendations for drainage, flooding, water quality, and riparian habitat. As a result, flood control improvements have been implemented along Chester Creek. The improvement area began at the Painted Hills Golf Course. In 1998, a project to install new culverts and extensive dredging of the channel between Thorpe Road and Schaffer Road was implemented. Two large volume borrow pits were constructed downstream. Each pit was designed for the retention and infiltration of Chester Creek floodwaters up to a 25-year event. One borrow pit was constructed just north of E. 40th Avenue and the other just south of 28th Avenue. The Chester Creek channel has been historically maintained as has been reported in the literature and supported by direct evidence of spoil piles on the channel banks. Dredging makes the channel deeper and the dredging spoil piles make the channel banks higher. As a result of channel dredging, the surrounding areas are dewatered faster and the water table falls a corresponding distance deeper below the soil surface. Soils in the areas mapped as NWI wetlands do exhibit some relic hydric characteristics from infrequent historical flooding, but with the exception of rare flood events, the water table is too far below the soil surface at the start of the growing season to meet the wetland hydrologic criteria. 14 The two mapped wetlands do not meet the hydrologic criteria so they are not wetlands. They are low lying areas adjacent to Chester Creek that have been historically flooded, but flooding is far too infrequent for the subject areas to meet the wetland hydrologic criteria. Even if they were wetlands, they are on the opposite side of the creek from where development is proposed so the riparian buffer would be more restrictive and extend further east into the development than a wetland buffer. However, there are no wetlands on the subject property. Additional flood control measures are being incorporated into the project design (see the Painted Hills Flood Control Plan). In the proposed Alternative #2, a thirty-foot wide by 3-foot- deep box culvert will be installed in the Right of Way to prevent back up on the Haase property south of Thorpe. On the north side of Thorpe, water will proceed northeast in an open concrete channel and headwall for two 48-inch pipes. The pipes extend northeast across the park to Madison Road where it will be piped north to a headwall and bioswale. The bioswale is a long sloping reach that terminates in a settling pond. At the settling pond, water will rise one foot and crest over a weir into the infiltration pond located at the north end of the development. Inland Pacific Engineering Company (IPEC) developed an Operations and Maintenance Plan for the facility to ensure the flood control systems receive regular maintenance and inspections to minimize long term effects of sediments that may enter the system. Other flood control measures will be required by the City of Spokane Valley who historically maintained the Chester Creek channel on an annual basis. To my knowledge, the channel was last dredged in 1998. The channel must be kept clear of deadfall that would impede flow in the channel. The property owners must implement the channel maintenance plan to insure flow in the channel is not impeded. WCE has also prepared a Chester Creek Levee Operation and Maintenance Manual for Level Operation and Maintenance for the Chester Creek Homeowners Association. This manual requires annual maintenance inspections and maintenance as required to maintain the integrity of the levee with additional inspections during all flood events. Fill material shall be placed behind the existing levee turning the levee into an engineered slope and eliminating the possibility of a levee failure during a flood event. Fill material will reinforce the creek bank and raise the bank elevation to a minimum height of one foot above the Base Flood Elevation. Raising the property to an elevation 1 foot above the base Flood Elevation ensures to FEMA and the City that the property, and buildings on the property, will not be inundated by a flood event. The fill material will slope to the northeast through the proposed streets, with their own proposed storm drainage systems, and the ultimate low point where flood control ponds will be constructed at the north end of the project. 4.9: Riparian Areas The DNR Water Type Map (Figure 5) defines Chester Creek as a Type F Water. Chapter 21.40 of the City of Spokane Valley Municipal Code, titled Critical Areas, bases stream buffer widths on the DNR Riparian Management Zones. Chester Creek is greater than 15 feet in width (bankfull) so the appropriate buffer width can be found in Table 21.40-10 of the City Code. The DNR guidance states that in Eastern Washington, if there is no site index information, as in this case, assume Site Class III unless site specific information indicates otherwise. The table indicates that a Type F Natural Water not classified as a Shoreline of the State, having a Site Class 3 designation, has a total buffer width of 100 feet. BSW delineated the Chester Creek OHWM in the field on March 31, 2015. The OHWM flags were surveyed and plotted on the site plan map along with the 100-foot riparian buffer by Whipple Consulting Engineers. 15 Map Output Page 1 of 1 '11 r FOREST PRACTICE WATER TYPE MAP TOWNSHIP 0 NORTH HALF undefined, RANGE 0 (W.M.) HALF undefined, SECTION Application #: 28454!2 2845464 2845448 -t- / 1 34 -1-e 2844486 46",84 844468 000 4/1/2015 9:23:14 AM NAD 83 Contour Interval: 40 Feet 4/ http://fortress.wa.gov/servlet/com.esri.esrimap.Esrimap?ServiceName=fpars&ClientVerson... 4/1/2015 The DNR Water Type Map also identified a Type F Water located about one mile east of the subject property. The map showed the stream crossing SR27 and running NW across a cultivated field before disappearing. There is no stream in that location so a Water Type Modification Form was submitted to Spokane County. The form was circulated to all appropriate agencies, the Water Type change was approved, and that stream segment was removed from the map. However, the FEMA map shows potential flood waters traveling toward the proposed development from that general direction. So additional work was required by FEMA to pipe the flood water to the borrow pit located on adjacent Gussman property to the north. Several years ago, the ditch was proposed, approved, and created to convey stormwater to a borrow pit. After the pipe improvements required by FEMA, floodwater will have the same fate as stormwater and be conveyed into the borrow pit where it will infiltrate and have no impact on the proposed development. No impacts are proposed to regulated waters by this FEMA requirement so no mitigation is required. 5.0: Analysis of Three Development Alternatives (Figures 6-8) 5.1: Alternative #1 (no development, Figure 6) The existing conditions would be maintained under the no development scenario of Alternative #1 (Figure 6). The existing conditions are turf grasses and vegetation consistent with a golf course with sparse woody vegetation bordering some of the fairways. The open space is utilized by deer and provides a potential travel corridor for elk moving between Madison Hills and Dishman Hills. These conditions would remain exactly the same in the Alternative #1 no development scenario. The entire property, stream buffer, trails, and bridges would remain in the existing condition. In the existing condition, the buffer on the right stream bank (N/E side of the creek) has an area of 104,131.93+/- sq. ft.. The buffer on the left stream bank (SANT side of the creek) has an area of 78,329.96 +/- sq. ft.. The total area of stream buffer is 182,461.89+/- sq. ft.. The existing buildings, trails, and bridges result in 18,604.23+/- sq. ft. of buffer impact. All of the existing impact areas would remain exactly the same if no development occurred. 5.2: Alternative #3 (standard residential development, Figure 7) In Alternative #3, a 3665.18 sq. ft. polygon on the west side of the creek, east of the existing restaurant parking lot, would be impacted (green hatched area in Figure #7). The 100- foot buffer width would be reduced to the 75-foot minimum width allowed by the City Code so the restaurant parking lot could be expanded. Alternative #3 also proposes a 1383.16 sq. ft. buffer impact (green hatched area in Figure # 7) from the City required improvement (widening) of Thorpe Road. According to the buffer averaging provisions of the City Code, buffer impact areas must be replaced with an equal or larger buffer area that is contiguous with the existing buffer so there is no net loss of buffer area. The 3665.18 sq. ft. and 1383.16 sq. ft. buffer impact areas total 5048.34 sq. ft. and would be replaced with a 5096.06 ft. sq. replacement area on the opposite side of the creek as represented by the blue hatched polygon in Figure # 7. The proposed 5048.34 sq. ft. buffer impact area would be mitigated with buffer averaging but also with vegetative enhancement of the buffer replacement area. The proposed buffer averaging will result in a small net increase in buffer area and habitat quality. On the right stream bank (N/E side of the creek) fill material will cover the entire 104,131.93+/- sq. ft. of riparian buffer to bring the land surface elevation to a height of one foot 17 BEi, 5E0.33, T.Z5N., R.44E., W.M. 5EC.34, T.25N., R.44E., W.M, NE , NEC. 4, T.24N., 5.445., W.M. CHESTER CREEK EXISTING DELINEATION & IMPACT STREAM BUFFER EXHIBIT KALE: • DATUM: NAVD - BB OF P.E.TUlt AMMO. SEWETIF,OECT ======.11. NAP. SCALE; PROJI, 13-114• 1.7. CMAINN: 2.1:1 FIEVIEWOO: TRW HOPISON17.1, A I JPP R.I.° PLANO 1 NO 1 DATE JPP 011101/.1. PRISPARICTION REVISIONS VCF1110.41., Nan — —• — 01101.1” N. CATER MARK (01-41.1) .15MC SiPEA4 OW. ORM., TON UNOURI0060 3555 MEAT 015-SAL5MICR S 811 au 11•1 MR. MIT 100K AREAS NE STREAM BUFFER 104.131.93 SF ± SW STREAM BUFFER 78,329,96 SF ± TOTAL — 182,461,09 SF ± EXISTING I M PACT AREA 1,572.9.3 SF 196,01 SF 1,206.33 SF A 3,726.54 SF 4,272.07 SF A 7,141.58 SF ± 488.67 SF ± TOTAL 18.604.23 SF ± Gay e1Spolunt Prol• CV Num', No.. SUBM15.10, 161.11x1A.10n) FP0.2016-0:07 ( ne.Plein Devalam•ntl O311.2.14-00, lenvin..0.1np) O .4 D r.ri 11.001.1 PA,M11,111. PLANS NOT APPROVED BY AGENCY E SPOKANE VALLEY PAINTED HILLS PRO EXIST. STREAM BUFFER EXHIBIT (ALT1) DISHMAN-MICA RD. SPOKANE VALLEY,WA SHEET 1 OF 3 JOB NUM2E11 13-1166 4) BE}, SEC.33, T.25N., R.44E., W.M. SW*, 5EC.34, T.25N., R.44E., W.M. NE * SEC. 4, T.24N., R.44E., W.M. CHESTER CREEK DELINEATION, IMPACT AND REMEDIATION LEGEN PHIL SC 25 50 I IR h SO It. (w FEEI ) 1 Inch F 00 Ft ""'''""'"'"74,T,';`,,STs(47-`) STREAM BUFFER REMEDIATION EXHIBIT DATUM: NAVD - 88 TBM55OF ThESOJIld KRA/ERMA SEWEEIRINSECE (LFRAFIF21. OF Asa, (SFRE02,2002 (Fr 1.X0FIR)ms us,u Eon KIVECNI.EATUFFI nits 4WCE 1.S0 SF ,/ I5350 PEussnam OWNS nOESxxst4 MAIL PROPER, ONE, Th.. OM IT SF 44.6 5 - OPDFNAAS RICK MUIR NEAR (CV.] STRESCIJEFER OFELINE.400,1 MIEN OF ENSTNG STREAM BUFFER TuFFACT RSA 41" PFICPOSEO SMEAR ourrcx IMPACT AREA OE STREAM AIRIER FIEFIECIATIOX sh IAIXEMOUND EJME Auer DIE—L41. NEMO t top 811 EMI no SAMS An ASA Al OFF AREAS NE STREAM BUFFER 104,131.93 SF A NE STREAM BUFFER REM, 5,096 06 SF ± SW STREAM BUFFER 78,329.96 SF TOTAL — 157,557.95 SF IMPACTS EXISTING IMPACTS: 1,572.93 SF 3,660.49 SF I 4,272.07 SF I 7,141.58 SF I + 48867 5F -I. 17,135.74 SF PRQP_PsED 3,565.18 SF ± 4 1 383 16 SF 5,048.34 SF TOTAL IMPACTS: 22,1E4.08 SF t REM EDIATIO N REMEOIAT1ON. 5,096.06 SF + 1.16 hiS TUISFE FIPV2.20hA SCALE: 1MIRIZOFFITA1.1 veanexi.: ARR, PPOJ Ix-11w oxrx 11/01111 ollAWRIF AFRO IFIIIVISW•12: RAW 1994,19 PAINTED HILLS PROP. STREAM BUFFER EXHIBIT (ALT 3) DISHWAKMICA RD. SPOKANE VALLEY,WA SHEET OF, 3 JOH NIIMBEFE 13.1166 above the BFE (see blue hatched area in the upper left corner of Figure # 7). The buffer is currently planted in non-native golf course turf grass and is almost totally devoid of woody vegetation. Only a handful of trees and shrubs would be impacted by the fill. This is a temporary buffer impact that will be mitigated by vegetative enhancement. No loss of buffer area will occur as a result of temporary impact. Existing trails will be removed and new trails of the same width will be built to replace the existing trails in the same location. Compared to Alternative #1, the trail impact area will be slightly less in Alternative #3 because some of the existing trail area will be eliminated. Alternative #3 proposes no new permanent buffer impact on the right stream bank (N/E side of the creek). The temporary buffer impact area on the right stream bank (N/E side of the creek) will be replanted with native grasses and native trees and shrubs at the industry standard rate of 350 stems per acre or 837 total plants. This represents a significant enhancement of wildlife habitat compared to the existing disturbed condition and previous land use as a golf course. Due to the proposed buffer width averaging, the Alternative #3 buffer total area would increase slightly (47.72 sq. ft.) compared to the existing condition. In Alternative #3, two small trail segments in the buffer totaling 1468.49 sq. ft. will be eliminated and not replaced so the Riparian Buffer area will also increase by that small amount compared to the Alternative #1 no development scenario. The remainder of the property would be developed with residential lots. In Alternative #3, the 10+ acre vegetated park/wildlife corridor along the southern border of the site would not be established and that area would be developed. Compared to the Alternative #1 no development scenario, Alternative #3 proposes 5048.34 sq. ft. of new buffer impact that would be replaced with a slightly larger 5096.06 sq. ft. replacement area as required for buffer width averaging. The proposed 5096.06 sq. ft. buffer replacement area would be enhanced with woody vegetative plantings. 5.3: Alternative #2 (Planned Residential Development, Figure #8) Alternative #2, a Planned Residential Development (PRD) is the preferred alternative due to the benefits of PRD mixed uses and the advantage of a 10+ acre park/wildlife corridor that is not offered in Alternative 3. Compared to Alternative #1, the Existing Buffer Impact Area is slightly smaller in Alternative #2 because some of the existing trail impacts in Alternative #1 are eliminated. The Alternative #2 and Alternative #3 scenarios both propose impacting the same 3665.18 sq. ft. buffer area polygon for expansion of the existing restaurant parking lot and the 1383.16 sq. ft. buffer impact from the required widening of Thorpe Road. Those two impacts are exactly the same as proposed in Alternative #3 and the impact area is included in the buffer averaging area. In Alternative #2, a 3665.18 sq. ft. polygon on the west side of the creek, east of the existing restaurant parking lot, would be impacted (green hatched area in Figure #8). The 100- foot buffer width would be reduced to the 75-foot minimum width allowed by the City Code so the restaurant parking lot could be expanded. Alternative #2 also proposes a 1383.16 sq. ft. buffer impact (green hatched area in Figure #8) from the City required improvement (widening) of Thorpe Road. According to the buffer averaging provisions of the City Code, buffer impact areas must be replaced with an equal or larger buffer area that is contiguous with the existing buffer so there is no net loss of buffer area. The 3665.18 sq. ft. and 1383.16 sq. ft. buffer impact areas total 5048.34 sq. ft. and would be replaced with a 5096.06 ft. sq. replacement area on the opposite side of the creek as represented by the blue hatched polygon in Figure #8. The proposed 5048.34 sq. ft. buffer impact area would be mitigated with buffer averaging but also 20 YI SE , 1600.23, T,2 5N., R.44E., W.M. SW , BEC.34, T.2519., R,44E., W.M. NE SEC. 4, 7,241.4„ R,44E., W.M. CHESTER CREEK DELINEATION, IMPACT AND REMEDIATION I I , 11 • LEGEN ( FEE TI 1 • 120 11. KG/11,1,1Z STREAM !SUFFER REMEDIATION EXHIBIT C19/151CO.T 1,512.93 552.69 61 141.30 51 — /-4 5143193/103 J 13B. • -- 'EEG EN D_ •—• — 0110/5511T HART 45. WAN (131111.) STREAM BUFFER 0221N/5110N SIKE115 GINTER 50E5 MCA CT COSTING 519115N BUFFER 1555C UREA OF PROPON9 51511. 011101271 501ACT MEM OF 57111.1 BUFFER BELE131519CN RCA& 1,50' 4. DATUM: NAVD - 88 31153601110 $019111101415105551.41431101 159,1591511NATON01 41351911956512093150.1115.150•111031.152,13/9111C31/05.1 0.191.1FOR 1E4 19/10 0ac4atoul4 20000 AWE irk 8 1 1 Nu 959904 15/015 100 115 AREAS NE STREAM SUFFER 98,80132 SF r. NE STREAM SUFFER REM 15,615.51 SF ± SW STREAM BUFFER 78,329.96 SF TOTAL. - 192,751.79 SF I M PA CTS EXISTING IMPACTS: 1,572.93 SF ± 2,174.04 SF' IN 4.272.C7 SF' ± 7,141.5$ SF ± F 488,67 SF ± 15,549.29 SE ± PADPOSEO IMPACTS: 857.69 SF ± 5616.36 SF ± 3,324.75 5F ± 249.65 sr ± 496.87 SF ± 3,665.18 SF ± + 1.383.16 SF ± 15,593,67 SF ± TOTAL IMPACTS: 31.242.96 SF A REM ED IATIO REMEDIATION 15,618.51 SF ± C1120(555955•NNY 1590411111111110N, 455-1011.0101 155141130,1013 1'151.10140907 50(Prowl Rain 0164905.56 50 110-5015 1551/1559retlOnAK0 05 5114951,Ano YUAN 0•9919,951 5.15.55, 0 Ctri=r 9.094.15.5 05,11.1.2 =Zeit Anew PLANS NOT APPROVED BY AGENCY 3 o 9.1 05.14.14 APB "07,7 /134111105 01-1.• 0111091110 ANAPANATON SCALE: 110111301.11A14 VONTICAU N/A 191110./ A: 13.1146 DATE: 05514/14 DRAWN: ONO 111111015331113, /TON moor AWCE .55.1.20.10.110015.291 15.NAKNA.9.04.45 951 n 59 ..59,5 SPOKANE VALLEY PAINTED HILLS PRD PROP. STREAM BUFFER EXHIBIT (ALT 2) DISHMAN.PSICA RD. SPOKANE VALLEY,WA SHEET 2 OF 3 JOB 131/ABEB 13-11E16 with vegetative enhancement of the buffer replacement area. The proposed buffer averaging will result in a small net increase in buffer area and habitat quality. This proposed buffer impact and the proposed mitigation is exactly the same as in Alternative #3, but the proposed buffer replacement area is in a different location. Compared to Alternative #3, the following additional 10,545.33 sq. ft. of buffer impacts are proposed in Alternative #2 on the right stream bank (N/E side of the creek). The additional impacts include three new trail segments and the extension of another trail segment. Some existing trail segments are eliminated in Alternative #2, and they offset part of the new trail impacts, but there will be a small net gain in trail impact area. The area of impact is included in the buffer replacement area proposed for impact mitigation. Alternative #2 proposes using buffer width averaging to reduce the buffer width by 25% on two lots adjacent to the southmost bridge (Figure #8). This will result in a 5616.36 sq. buffer impact that will be mitigated with buffer averaging. The Alternative #2 total combined buffer impact area is 15,593.67 sq. ft. Buffer Averaging is proposed for impact mitigation. The proposed Buffer Impact Replacement Area is 15,618.51 sq. ft. There will be no net loss of buffer area as a result of averaging. The Buffer Replacement Area is contiguous with the existing buffer. The mitigation area will be enhanced with the planting of trees and shrubs. The mitigation area is contiguous with the proposed 10+ acre Park/Wildlife Travel Corridor. Clusters of woody vegetative plantings will also be installed in this corridor to enhance wildlife habitat. 5.4: Summary of Alternative 1, 2, and 3 Buffer Impacts The existing trail areas differ in all three alternatives because the trail segments that are both eliminated and added in Alternative #2 and Alternative #3 are different. The Thorpe Road improvement Area impacts are the same for Alternative 2 and 3. Buffer impacts from the proposed parking lot expansion area on the left (S/W) side of the creek are the same for Alternative 2 and 3. Buffer Averaging is proposed for mitigating those buffer impacts and the replacement areas have the same square footage in both Alternatives 2 and 3. In both Alternatives #2 and #3, the 104,131.93+/- sq. ft. riparian buffer on the right stream bank (N/E side of the creek) will be filled with soil to a height of one foot above the Base Flood Elevation (see blue hatched area depicted in inset at top left corner of Figures 7 and 8). The buffer is currently planted in golf course turf grasses and is nearly devoid of woody vegetation. This temporary impact area will be mitigated by reseeding the area in native grasses and planting clusters of native woody vegetation. This will result in a significant improvement in buffer quality. Alternative #2 proposes additional buffer impacts by reducing the 100-foot buffer width to 75 feet on two lots adjacent to the southmost bridge on the right stream bank (N/E side of the creek). That 5616.36 sq. ft. buffer impact is not proposed in Alternative #3 so the buffer replacement area is proportionally larger in Alternative #2. The buffer replacement area will be enhanced by planting native trees and shrubs. Alternative #2 also proposes a 10+ acre Park/Wildlife Habitat Travel Corridor across the southern project boundary that is not proposed in Alternative #3. The 10+ acre Park/Wildlife Habitat Travel Corridor (Figure 3) will be enhanced by the planting of native trees and shrubs. 5.5: Temporary Buffer Impact Mitigation Any peripheral buffer areas that are inadvertently disturbed during construction will be planted with the specified native seed mix to prevent erosion. This work will be completed in 22 strict accordance with the IPEC Operation and Maintenance Manual and Best Management Practices. 5.6: Buffer impact Area from the Chester Creek Culvert Extension Thorpe Road will be made wider along its north side to meet City standards that require an additional 6.5 feet of pavement, a 2-foot curb, and 6-foot sidewalk. This will result in 1383.16 sq. ft. of riparian buffer impact. The impact area includes a new box culvert under the new road construction. A crane will install the concrete box culvert that will be capped and paved over. The culvert will be an extension of the existing culvert and will not cover or change the existing substrate on the stream bottom. All in-channel and over-channel work will occur during the summer/fall dry season so no over-water or in-water work will be required. The area of impact is counted in the total project buffer impact area calculations, buffer averaging replacement area calculations, and vegetative plantings are prescribed for the impact area as part of the proposed buffer impact mitigation for the project. 6.0: Rationale for Adjustment (Reductions) of Riparian Habitat Buffer The City of Spokane Valley Municipal Code, Section 21.40.034 states that "the habitat buffer width may be averaged (reduced in width near a development but widened elsewhere to retain the overall area of the habitat buffer) if all of the following conditions are met. Each proposed buffer impact and reduction is discussed in the following section in the context of the conditions set forth in the City Code. 1) The FWHCA has significant differences in characteristics that affect its habitat functions, such as a native forested component adjacent to a degraded herbaceous component. Alternative #2 Buffer Impacts from Two Lots A proposed 25% buffer reduction resulting in 5616.36 sq. ft. of buffer impact is proposed on the right stream bank (N/E side of the creek). The proposed impact is in close proximity to the southmost bridge across Chester Creek. The proposed buffer impact area is planted in non- native golf course turf grasses. The turf grass was maintained by treatment with herbicides and regular mowing. The proposed impact area has no trees and only one shrub. The 5616.36 sq. ft. area of proposed buffer impact experienced the highest intensity human activity on the property during the years of golf course operation. Foot and golf cart traffic from the club house was directed by cart paths over two bridges to the fairways, driving range, and practice areas across the creek where the buffer impact from two lots is proposed. In the Alternative #2 and #3 site plans, the existing bridges will be utilized and the golf cart paths will be extended east to connect the housing development on the east side of the creek to the bar and restaurant located in the former golf course clubhouse on the west side of the creek. Due to the existing trails and bridges, the Alternative #2 proposed area of buffer width reduction from two lots will continue to experience the highest intensity human activity on the property. This part of the buffer experienced the highest degree of historical degradation and will continue to experience the greatest intensity of human activity and foot traffic on the existing trails and bridges. The proposed impact area occurs in an existing highly disturbed area that would benefit the least from protection because this area did not function as buffer historically and from a habitat perspective will not in the future due to the intensity of human traffic funneled through this corridor. Mitigation for the proposed buffer impact is proposed 23 where it will have the greatest benefit for wildlife and greatest habitat function. If development is approved under Alternatives #2 or #3, then the buffer impact from Thorpe Road improvements is an unavoidable impact. The impact area immediately adjacent to the road provides the least habitat function on the property. The buffer replacement area will part of the best habitat on the property. If development is approved under Alternatives #2 or #3, then the buffer impact from expanding the existing parking lot on the left (west) side of the creek is the same for both alternatives. The impact area is immediately adjacent to an existing parking lot and building. The historically disturbed, high human traffic area has only herbaceous vegetation with no trees or shrubs to provide wildlife cover or habitat. The area where the buffer reduction is proposed will be enhanced with native trees and shrubs as will the buffer replacement area. The buffer reduction is proposed in a degraded herbaceous habitat component. The buffer will be replaced adjacent to the proposed 10+ acre wildlife corridor that will be enhanced with clusters of native trees and shrubs. 2) The buffer is increased adjacent to the higher functioning area of habitat or more sensitive portion of the FWHCA and decreased adjacent to the lower functioning or less sensitive portion. The area where a 25% buffer reduction is proposed for two lots is the most disturbed buffer area on the site and the area where intense human activity will occur due to the existing trails and bridges that link the development on the east side of the creek to the commercial area on the west side of the creek. The trails and bridges create a corridor that runs perpendicular to the creek. The corridor passes through the entire buffer on both sides of the creek and funnels all human activity through that corridor. This area of concentrated activity is the lowest functioning part of the buffer on the property. This corridor for human traffic did not historically function as a buffer and will not in the future under either Alternative #2 or #3 development scenarios. North of the area proposed for buffer reduction is a large area of open space on the right stream bank (N/E side of the creek) that extends out away from the buffer and effectively widens the buffer in that area. This area will have a much lower level of human activity compared to the trail and bridge corridor. This is a higher functioning area of buffer compared to the proposed buffer reduction area. The buffer addition area is located south of the buffer impact area and expands the buffer eastward to connect with the designated wildlife travel corridor where human activity will be reduced to a minimum. The buffer replacement area will be planted with native grasses and clusters of native trees and shrubs. The intent is to make the buffer wider where there is least human activity and provide the most benefit for wildlife. Habitat functions are lowest where the reduction is proposed and highest where the buffer replacement will occur in a proposed wildlife travel corridor where dense vegetative plantings will be installed to enhance the existing woody vegetation and wildlife habitat. The buffer width increase will occur in the higher functioning area of habitat as suggested by the City Code and decrease adjacent to the least sensitive buffer. The Park/Wildlife Travel Corridor covers the entire southern border of the property, is over 350 feet wide, and has an area of over 10 acres. Variations in sensitivity are created by the existing physical characteristics (bridges and trails), historical land uses (vegetation removal and intense human activity), and the continued concentration of human activity on trails and bridges through that narrow corridor across the stream and buffer on both sides. That corridor has the least habitat function because it has the 24 least wildlife activity. The proposed buffer impact will occur in the least sensitive area from the perspective of wildlife presence, use, and function. Buffer enhancement will occur where there is the least human activity and the greatest benefit from the perspective of wildlife presence, use, and function. The total area contained within the buffer after averaging is greater than that contained within the standard buffer prior to averaging. 3) The total area of the buffer, after averaging, is equal or greater than the area required without averaging. The buffer averaging proposed in Alternatives #2 and #3 result in a small increase in buffer area. Alternative #3 proposes a total buffer impact area of 5048.34 sq. ft. (0.116 acres). Alternative #3 proposes a total buffer impact replacement area of 5096.06 sq. ft.(0.117 acres). Alternative #2 proposes a total buffer impact area of 15,593.67 sq. ft. (0.358 acres). Alternative #2 proposes a total buffer impact replacement area of 15,618.51 sq. ft. (0.359 acres). No net loss of buffer will occur from Alternative #2 or Alternative #3. 4) The buffer at its narrowest point is never less than 75 percent of the original habitat buffer width. Alternatives #2 and #3 propose buffer averaging. In each instance, the buffer will be reduced from 100 feet to 75 feet, so the buffer is not reduced to less than 75% of the original habitat buffer at any location. Mitigation Rationale Summary The continued use of the two bridges and trails crossing the stream and buffer has the effect of funneling, controlling, and limiting human access to this narrow corridor or choke point. Buffer reduction for two lots is proposed immediately adjacent to the high intensity human use corridor in the buffer. Three separate buffer impacts will occur from trails. Two of the impacts will result when the existing, trails are extended from the bridges into the development and connected to a proposed trail in the 10+ acre wildlife travel corridor. The proposed buffer mitigation provides adequate compensation for the proposed impacts as defined by the City Code. The areas of proposed buffer reduction will be enhanced by the planting of native tree and shrub patches. The remaining riparian buffer will also be enhanced by planting patches of native woody vegetation on both sides of the stream. The buffer replacement area will be enhanced by the planting of native tree and shrub patches. The buffer replacement area will be contiguous with the Wildlife Travel Corridor where additional tree and shrub plantings are proposed. Alternative #2 is the preferred alternative because it provides the 10+ acre Park/Wildlife Travel Corridor not included in Alternative #3. The proposed vegetative enhancement of the remaining buffer areas, replacement buffer areas, and wildlife travel corridor provides generous mitigation to offset the impacts. The proposed vegetative enhancement represents a significant improvement compared to the existing condition and historical land uses of the last several decades. Mitigation Sequencing Several development plans have been scrutinized over the last three years by the City of Spokane Valley and various firms employed to certify the levee on the right (east) bank of Chester Creek. Numerous changes have been implemented to the storm-water and flood control 75 plans for the site in order to arrive at the preferred final site plan. The levee certification involved earthwork on the levee, removal of all vegetation in the stream channel, and other options required for development approval. Those plan were all abandoned in favor of the three development alternatives analyzed in this report. In the end, Alternative #2 was favored by the City and the developer. While the preferred alternative results in more buffer impact than the other two alternatives, it was determined that the buffer enhancements and vegetative plantings proposed to improve habitat, the advantages of a Planned Residential Development, and the creation of a 10+ acre Park/Wildlife Travel Corridor far outweighed the benefits of the other two alternatives. The preferred alternative was determined to avoid the most impacts, minimize impacts to the stream channel. and provide the most benefits. 7.0 Impact Mitigation Strategy 7.1: Noxious weed control The dominant invasive species that were identified on the site include tumble mustard and knapweed. These species are known for their ability to propagate and spread rapidly with catastrophic impacts on native species. As required by Washington State Noxious Weed Control law, RCW 17.10, and the Spokane County Noxious Weed Board, invasive species will be managed through control measures that do not adversely impact native vegetation. Funds will be allocated for noxious weed monitoring and herbicide control as part of the proposed mitigation for this project. Black Realty or their designated Homeowners Association shall contract their preferred weed control specialist to monitor the site and provide weed control in the mitigation areas at appropriate intervals throughout the growing season to prevent seed set. 7.2: Revegetation with Woody Plants In addition to noxious weed control, mitigation for buffer impacts will include the planting of native trees and shrubs. The buffer will be re-vegetated with native plants including species from the tree, shrub, and grass vegetative strata. The replication of natural spatial relationships, structural complexity, vertical stratification, and microhabitat diversity will be stressed in the planting design to achieve a mosaic of open areas and dense tree/shrub clusters. Vegetation will not be planted in a uniform manner. Shrubs will be planted in grouped patches and interspersed with other shrub species and height classes. Patch size will be variable with curving edges. The incorporation of these elements will increase landscape diversity and promote habitat elements that are often scarce or absent at sites that have been disturbed. Native species and endemic plant materials will be selected for site revegetation to help maintain ecotypes that are adapted to local climatic and soil conditions and preserve local genotypes. 7.3: Rationale Structural complexity refers to the arrangement and degree of interspersion of plant community types throughout the system. Complex structural patterns (such as variable patch size, curving edges, and high degree of interspersion between species) increase the value of a system for wildlife. Good wildlife habitat consists of open areas interspersed with clusters of vegetation, several horizontal layers, and a variable structural pattern. Vertical stratification describes a community with good structural diversity and several horizontal layers (logs, woody debris, forbs, shrubs, and trees). Woody debris provides travel routes, perch sites, cover, and thermal refuge for a variety of small mammals and ground nesting birds. Microhabitat diversity refers to variety in microhabitat types. Examples of microhabitat types include 26 herbaceous cover and shrubs that provide food, habitat, and substrate for a variety of animals. 7.4: Objectives for the Restored Riparian Buffer Restoration will be achieved by planting native trees, shrubs and grasses primarily to provide food and cover for wildlife. The Vegetation Plan will incorporate as many design features as possible for each function in order to increase the value for that function. Objective a: Re-establish species diversity and structural diversity in the buffer by replanting native tree and shrub species from each vegetative class. Objective b: Re-establish vegetative species and structural diversity to re-establish bird and mammal habitat values in the enhanced buffer areas. Objective c: Re-establish vegetative density in the riparian buffer area. 8.0: Mitigation Planting Plan Woody plant materials will be installed at the industry standard density of 360 stems per acre. The buffer replacement area is 15,618.51 (0.359 acres) X 360 stems/acre = 130 containers. The Buffer Replacement Area shall have 130 containers planted within that polygon. An additional 100 containers will be distributed throughout the east and west sides of the creek in the buffer reduction areas (Zone 1 and Zone 2, Figure 9). An additional 200 containers shall be planted in patches of 20 containers throughout the designated wildlife travel corridor. An additional 200 containers shall be planted in patches of 20 containers throughout the buffer on the right stream bank (N/E side of the creek) where fill material will create a temporary 104,131.93+/- sq. ft. (2.39 acres) buffer impact. The 2.39-acre area of temporary impact will also be seeded with the prescribed native upland grass seed mix. Clusters of vegetation will be planted according to the guidelines prescribed above. The specified number of containers will be planted within each zone as shown in Figure 9. Area Mitigated buffer reduction areas right stream bank fill impact area buffer replacement Area wildlife travel corridor total Number of Plants Zone 100 1 250 1 130 2 150 3 630 Zone 1: Riparian Buffer on East and West Sides of Chester Creek A total of 350 containers planted in existing buffer areas Common Name Scientific Name # Planted Trees Ponderosa pine Pinus ponderosa 20 Large shrubs serviceberry Amelanchier alnifoloia 20 Rocky mountain juniper Juniperous scopulorum 30 mock orange Philadelphus lewisii 80 Small shrubs Wood's rose Rosa woodsii 60 common snowberry Symphoricarpos albus 60 Phlox sp. Phlox speciosa or longifolia 80 Total 350 27 // 2 g 1 .1 / SE1, SEC.3 3, T.25N., R.446., W.M. SW , 5E0.34, T.25N., R.44E., W.M. NE SEC. 4, T.2 4N., 18.44E. W.M. CHESTER CREEK DELINEATION, IMPACT AND FREMEDIATION — )-'-'\ 1 I ,, A , , ItI ' 1 9 ; 1 1 f: 43 III GRAPHIC SCALE ( lR 1158-• ) I DNA • IDO rt. `" 1PI00RAnr SmCAu °"7:4ct.g VP-2 Ilt [I , -I {n GRAPHIC SCALE 9irils —J --'_Ia— I IS• IN T -otTO ) rics,71rY \\- /airtime UNE. 1I7 cIaRNEcnun aME 857 OS sr / •;/ , / I ,re . I. AREA OF ArDUC FROM ICC IC IE. TN, HEUSI. 14,50 SF *51 ‘1, 10E--6 N — ORDINARY HIGH SAYER MARX (OH WM) STREAM BUFFER CalhEATICH TY UN Im /iee 6T SF ,te." • a , TWR 110.0,1 -I EN / 5,REAAI ',OFFER AREA AREA Cr errrnAr SIRE Au SUFFER IMPACT AREA OF PROPOSCO MEAN Et/FFER IMPACT MCA Or SINEAll 6U7YIR RENDIDADON STREAM BUFFER REMEDIATION EXHIBIT Q DATUM: NAVD - 88 1B4 8-5 0,1150.11 FOYLICROCA SEAT', IHOYCT .101 V ICTI 01.10053,111.4.11 .10.01 OIAT.I.SH WAS 110.0 OR NC VLF, 09, 501164 FOR /I C. Zon-e Zoete g '2.®n*Ci SCALE: ORIZONTAL. 1....00/ .100 VERTICAL. 'WA PROJ Ie 12-TIRO DATRI 08,141111 °PAWN: MHO REVIEWED TRW /WCE AMA. 0.1..51.G.FIA1 LAIMORAIMILVONOOD 1.0%.1,1411,. AMY MESEACM10 AIM 0E-MIA1 811 .11•131. FOS FOAM 10111111 AREAS NE STREAM BUFFER 98,803.32 SF ± NE STREAM BUFFER REM. 15.618.51 SF ± SW STREAM BUFFER 78,329.96 SF ± TOTAL — 192,751,79 SF I M PACTS EXISTING IMPACTS' 1,572.93 SF t 1,174.04 SF ± 4,272.07 SF 7,141,58 SF + 488.67 SFA 15,549.29 SF ± PROPOSED *WAD'S: 857.69 SF ± 5616.36 SF 3,324.75 SF ± 249.66 SF ± 496.87 SF A 3,665.18 SF + 1.383.16 SF ± 15.593.67 SF ± TOTAL IMPACTS' 31,242.95 SF REM ED I ATI N REMEOIATION: 15,618.51 SF ± PLANS NOT APPROVED BY AGENCY SPOKANE VALLEY PAINTED HILLS PRD PROP. STREAM BUFFER EXHIBIT (ALT 2) DISNMAN•MICA RD. SPOKANE VALLEY,WA at, tx 8501111 wary rtattatr•mottle. •1111.101.001 1.11.111.1.1 1011.027 (.1114:1AAIMmettm.,0 dOM OUR... ORIN* OvraolIR.ment O. r. Tri SHEET 2 OF 3 JON 010,06118 13-118S Zone 2 - Buffer Replacement Area 130 plants in patches Common Name Trees Ponderosa pine Large shrubs serviceberry Rocky mountain juniper chokecherry mock orange Small shrubs Wood's rose common snowberry Phlox sp. Total on East Side of Chester Creek Zone 3 - Wildlife Travel Corridor o 150 plants in patches Common Name Trees Ponderosa pine Large shrubs serviceberry chokecherry mock orange Small shrubs Wood's rose common snowberry Total Scientific Name Pinus ponderosa Amelanchier alnifoloia Juniperous scopulorum Prunus virginiana Philadelphus lewisii Rosa woodsii Symphoricarpos albus Phlox speciosa or longifolia # Planted 5 10 10 10 30 20 25 20 130 n East Side of Chester Creek Scientific Name Pinus ponderosa Amelanchier alnifoloia Prunus virginiana Philadelphus lewisii Rosa woodsii Symphoricarpos albus # Planted 20 20 10 40 30 30 150 The minimum container size shall be one half gallon. Vegetation shall be planted at the landscapers discretion according to conditions on the ground and the location of existing vegetation. Plantings shall be interspersed around existing vegetation, and where possible, in patches of 15-25 plants of mixed size and species as indicated in the plan. Shrubs shall be planted in the approximate prescribed quantities depending on plant availability. Large shrubs should be planted in clusters on 10-foot centers. Small upland shrubs should be clustered on 3-6 foot centers around large shrubs. Depending on availability, the mixture of grass species listed below should be drill seeded or hydroseeded at a density of 22 pounds PLS per acre in all disturbed areas. Grasses should be planted during the growing season when precipitation and temperature levels will insure germination and survival. Grasses should be planted early in the fall so that the crop is well established by October 15. If germination, growth, and root development are substantial before the end of the growing season, some degree of erosion control will be provided during the winter and spring months that follow. It may be necessary to irrigate the soil surface to keep it in a moist condition for the first two weeks after seeding. Irrigation should supplement rainfall as required to achieve a total from combined sources of 2 inches per week and no more than 0.25 inches per hour. Seed can also be installed to lie dormant over the winter and germinate in the spring. 28 Grasses Common Name Scientific Name Bunch or Sod PLS (lb/acre) bluebunch wheatgrass Idaho fescue prairie junegrass Agropyron spicatum Festuca idahoensis Koeleria cristata B B B 8.0 6.0 8.0 Total 22.0 A list of suppliers who will prepare the prescribed grass seed mixtures and supply nursery stock specified in the vegetation plan follows. Grass seed: Grassland West PO Box 489 908 Port Drive Clarkston, WA 99403 Trees, & Shrubs: 1-800-582-2070 Plants of the Wild PO Box 866 Tekoa, WA 99033 509-284-2848 Wildlife Habitat Institute 1025 East Hatter Creek Road Princeton, ID 83857 208-875-8704 8.1: Ponderosa Pine Planting ALWAYS plant after December 15 and before March 31. Plant ONLY conservation grade seedlings 20-24 feet from fast growing deciduous trees. Plant seedlings on 30 foot centers with no shrubs inter-planted close to the trees to prevent shading and competition that greatly reduces survival. A mulch of Ponderosa pine needles applied in a 3-6 foot radius around the tree trunk at planting will greatly reduce competition and increase tree survival. Ponderosa pine out-planting survival following Rhizopogon rubescens inoculation is 2-3 times higher compared to non-inoculated. Numerous studies have shown that ectomycorrhizal fungi can profoundly affect conifer performance by facilitating nutrient and water uptake, maintaining soil structure, and protecting roots from pathogens and environmental extremes. A specific ectomycorrhizal fungus, Rhizopogon rubescens, inoculated onto the root systems of Ponderosa pine seedlings greatly increase survival. Irrigation options are being explored at this mitigation site, but the landscaper should buy plants that have been inoculated or dust the planting holes with this fungi if it is available. 8.2: Additional Planting Guidelines Depending on availability, the mixture of grass species listed above should be seeded at a density of 22 pounds PLS per acre. Grasses should be planted during the growing season when precipitation and temperature levels will insure germination and survival. Grasses should be planted in early April so that the crop is well established before dry weather, in the fall so that the crop is well established before October 15, or dormant seeded late in the fall so the seed will not germinate until spring. Site preparation and planting should occur in the fall and winter. Seeding rates of live, genninable seed or Live Pure Seed (LPS) are a product of seed lot purity and germination percentage. LPS calculations are based on the number of seeds per pound and the number of seeds per square foot at one pound per acre. A nursery will prepare a custom seed mix with the prescribed LPS for each species. 29 Trees and shrubs should be planted after the end of the growing season when the plants are dormant. The best time to plant is late winter when sub-zero temperatures are over but plants are still dormant. Plants may be planted any time during the growing season when the daytime high temperatures are 70F or cooler if irrigation is available from the time of planting through the rest of the growing season. Each tree or shrub planted should be clearly identified with an easy to identify tag that identifies the species. Without such identification it is impossible for the monitoring biologist to tell which plants are enhancement plantings and which are native to the site. 8.3: Additional Fish and Wildlife Habitat Mitigation Requirements Area irrigation heads should be installed where native grasses are planted to insure germination and survival in the buffer enhancement areas. Drip irrigation should be installed for woody plantings where there is no coverage by area sprinkler heads. Irrigation shall continue until the plants are well established as determined by the project biologist. Mitigation plantings should be installed no later than the next growing season after completion of the buffer impacts, unless otherwise approved by the City Manager or designee. The timing may also depend on the installation of utilities and water supply for irrigation and will proceed as soon as those amenities are available. Regardless of which year construction begins, it is known that the first construction phase will include the stormwater plan and fill on the east side of the stream. The irrigation should be installed at the same time as the plantings. BSW will monitor site impacts and mitigation work to insure the work is completed as specified in this plan. The five year monitoring requirement for each phase will be implemented as described below. Mitigation areas shall be maintained to insure the mitigation and management plan objectives are successful. Maintenance shall include corrective actions to rectify problems, including rigorous, as-needed elimination of undesirable plants; protection of trees and shrubs from herbivory and competition by grasses and herbaceous plants; and repair and replacement of any dead woody plants. People may drive, park and passively enjoy recreation in the area so the enhancement areas must be protected from human traffic after planting. Signs should be posted every 100 feet to explain the sensitivity of the newly planted areas and discourage foot traffic in newly seeded areas. Permanent signs with Riparian Buffer Area, Natural Area Do Not Disturb, or similar language should be posted around the protected areas. 8.4: Willow Monitoring and Maintenance of the Chester Creek Channel Honey willows were planted in the channel about thirty years ago. All subsequent channel maintenance and dredging has avoided the willows that have now grown quite large. Honey willows are prone to dropping very large branches that catch additional debris and create channel obstructions, as will the trees themselves when they die and fall into the channel. The channel must be monitored regularly so potential obstructions may be identified and removed to eliminate potential problems as is required by the Inland Pacific Engineering Company (IPEC) Operation and Maintenance Manual. If channel obstruction, erosion, or maintenance is required, Best Management Practices and spill control protocols will be strictly adhered to and peripheral impacts will be held to a minimum. The channel may be dry, but the equipment operators must respect the sensitivity of 30 the area, install construction fences to identify minimized work areas, and take all prudent measures to minimize impact in the buffer. All temporary impact areas will be restored at the earliest possible moment to prevent soil erosion. The replacement woody vegetation plantings cannot be placed in or within 15 feet of the stream channel all replacement planting will occur in the riparian buffer and wildlife travel corridor as detailed later in this report. 8.5: Timeline for Construction Construction will begin as soon as permitted in 2019/2020 and continue is phases over the next few years. 8.6: ESA Compliance The purpose of this report is to confirm that the project is in compliance with Sections 9 and 10 of the Endangered Species Act. The proposed project will have no effect on any listed species. Mitigation actions are enhancement of the existing facility and the proposed changes will have no effect on any listed habitat or species. 9.0 THE MONITORING PLAN All monitoring plans require that a mitigation site be monitored annually to determine whether the goals and performance standards have been met. Monitoring typically lasts for 5 years or until the City of Spokane Valley is satisfied that the conditions of the mitigation plan have been met. The site should be monitored in the spring to evaluate the success of weed control from the previous year and prescribe weed control for the current year. The monitoring will also evaluate plant survival to insure that performance standards for percent ground cover of native vegetation are met. Planting of the original grass seed mixture will be repeated to fill in problem areas if they occur. The City of Spokane Valley will be notified immediately after diagnosis of failing functions, hydrologic systems, or biological vitality and integrity of the plantings as determined through annual monitoring. The herbaceous vegetation will be managed to insure 80% areal cover with native grasses after five years (year 1=20%, year 2-30%, year 3=50%, year 4=70%, year 5=80%). Tree and shrub stock will be monitored to insure 100% survival after the first year and 80% for each subsequent year. Reinforcement plantings will be performed annually as necessary to insure performance standards are met at the end of five years. If the final monitoring report clearly demonstrates that the site has achieved all of the goals and objectives set forth in this Habitat Management Plan, then the applicant shall be released from additional mitigation and reporting obligations. However, if performance objectives are not me at the end of five years, additional measures shall be implemented as required until the mitigation objectives are met. 31 10.0 Cost of Implementing Mitigation and Surety The cost of purchasing and installing vegetation, weed control, replacement plantings, site monitoring, and reporting for 5 years is estimated below. 630 stems @ $28/stem = $17,640.00 2 acres X 22/lbs per acre = 441bs. X $80/lb = $3,500.00 hydroseeding A $3000 per acre X 2 acres = $6,000.00 Annual weed control A $10000/yr = $50,000.00 Year 1 monitoring + as-built report $3,000.00 5 years monitoring @ $800/year = $4,000.00 5 years monitoring reports @ $1000/yr $5,000.00 630 stems X 15% annual mortality replacement = 95 stems/yr X $28/stem = $2,660.00X 5 yrs = $13,300.00 Total cost for 5 years $102,440.00 10.0 LIMITATIONS Within the limitations of scope, schedule, and budget, BSW services have been executed in accordance with best available science and generally accepted professional practices for the conditions at the time the work was performed. This report is not intended to represent a legal opinion. Specifically, there is no positive or negative recommendation towards the purchase, sale, lease, or construction on the subject property. No warrant, expressed or implied, is made. arry ■ awes Principal Bi• ogist Biology Soil & Water, Inc. 3102 N. Girard Road Spokane Valley, WA 99212-1529 Phone 509-327-2684 Email: bswincgicehouse.net 5-4%2 0/7' Date BIBLIOGRAPHY AND SUGGESTED REFERENCES Berglund, Erwin R.. 1976. Seeding to Control Erosion Along Forest Roads. Extension Circular 885. Oregon State University Extension Service. 6-8p. City of Spokane Valley Municipal Code Carroll, Carlos; Noss, Reed F.; Paquet, Paul C. 2001. Carnivores as focal species for conservation planning in the Rocky Mountain region. Ecological Applications. 11(4): 961-980. Cooper, Stephen V., Kenneth E. Neiman, and David W. Roberts. 1991. Forest habitat Types of Northern Idaho: A second Approximation. USDA: Forest Service; Intermountain research Station. General Technical Report INT-236. 143 p. Dale, B. C. 1983. Habitat relationships of seven species of passerine birds at Last Mountain Lake, Saskatchewan. M.S. thesis. University of Regina, Regina, Saskatchewan. 119 pages. Daubenmire, R. 1969. Structure and ecology of coniferous forests of the northern Rocky Mountains. Pages 25-41 in R. D. Taber, ed. Coniferous forests of the Northern Rocky Mountains. Univ. Mont., Missoula. 395pp Davis, S. K. 2004. Area sensitivity in grassland passerines: effects of patch size, patch shape, and vegetation structure on bird abundance and occurrence in southern Saskatchewan. The Auk 121: 1130-1145. Delaney, Kevin. 1994. Wildlife Notebook Series. Alaska Department of Fish and Game, http:/www.hitime.com.sdscptn.htm. FERC. 2006. Draft Environmental Impact Statement. Spokane River and Post Falls Hydroelectric Projects. Federal Energy Regulatory Commission. Office of Energy Projects. December 2006. Forman, R. T. and M. Gordon. 1986. Landscape Ecology. John Wiley and Sons, New York. 619 p. Frissell, C.A. 1992. Cumulative effects of land use on salmonid habitat on southwest Oregon streams. Oregon State University, Corvalis, OR. Grubb, P. J. 1977. The maintenance of species richness in plant communities: The importance of regeneration niche. Biological Review 52: 107-145. Hitchcock, C. Leo, and Arthur Cronquist. 1994. Flora of the Pacific Northwest. University of Washington Press, Seattle, WA. 730p. 33 Hitchcock, C. L., A. Cronquist, M. Ownbey, and J.W. Thompson. 1964. Vascular Plants of the Pacific Northwest, Part 2: Salicaceae to Saxifragaceae. University of Washington Press, Seattle. 597 pp. Koehler, Gary M. 1990. Population and habitat characteristics of lynx and snowshoe hares in north central Washington. Canadian Journal of Zoology. 68: 845-851. Koehler, Gary M.; Aubry, Keith B. 1994. Lynx. In: Ruggiero, Leonard F.; Aubry, Keith B.; Buskirk, Steven W.; Lyon, L. Jack; Zielinski, William J., tech. eds. The scientific basis for conserving carnivores: American marten, fisher, lynx, and wolverine in the western United States. Gen. Tech. Rep. RM-254. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station: 74-98. Koehler, Gary M.; Britten, J. David. 1990. Managing spruce-fir habitat for lynx and snowshoe hares. Journal of Forestry. 88(10): 10-14. Koehler, Gary M.; Hornocker, Maurice G.; Hash, Howard S. 1979. Lynx movements and habitat use in Montana. The Canadian Field-Naturalist. 93(4): 441-442. Maher, W. J. 1973. Matador Project: Birds I. Population dynamics. Canadian Committee for the International Biological Programme, Matador Project, Technical Report 34. University of Saskatchewan, Saskatoon, Saskatchewan. 56 pages. Mancuso, Michael, December 2000. Field Investigation for Spiranthes Diluvialis (Ute Ladies- tresses) on BLM Lands Managed by the Shoshone Field Office, South- Central Idaho. Conservation Data Center Martin, A. C., H. I. Zim, and A. L. Nelson. 1951. American Wildlife and Plants. Diver Publications, Inc., New York. 484 p. McCaffery, K. R., and W. A. Creed. 1969. Significance of forest openings for deer in northern Wisconsin. Technical Bulletin 44. Madison:Wisconsin Department of Natural Resources. 104 p. Moseley, R.K. 1998. Ute ladies tresses Spiranthes diluvialis in Idaho: 1997 status report. Report prepared by the Idaho Conservation Data Center, Boise, ID. Murray, Dennis L.; Boutin, Stan; O'Donoghue, Mark. 1994. Winter habitat selection by lynx and coyotes in relation to snowshoe hare abundance. Canadian Journal of Zoology. 72(8): 1444- 1451. NatureServe. 2010. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. (PBTTAT) Panhandle Bull Trout Technical Advisory Team. 1998. Coeur d'Alene Lake Basin bull trout problem assessment. Draft. Prepared for the State of Idaho. December 1998. 34 Sauer, J. R., J. E. Hines, and J. Fallon. 2005. The North American Breeding Bird Survey, Results and Analysis 1966 - 2004. Version 2005.2. USGS Patuxent Wildlife Research Center, Laurel, MD Simpson, J.C., and R.L. Wallace 1982. Fishes of Idaho. Department of Biological Sciences, University of Idaho, Moscow. Singer, F. J. 1979. Habitat partitioning and wildlife relationships of cervids in Glacier National Park, Montana. Journal of Wildlife Management. 43(2):437-444. Spokane County Public Works Department: Building and Planning Division. 1996. Critical Areas Ordinance for the Protection of Wetlands, Fish and Wildlife Habitats and Geo- hazard Areas. Spokane County, WA. 69p. Stephens D. A. and S.H. Sturts. 1997. Idaho bird distribution. Idaho Museum of Natural History, Pocatello and Idaho Department of Fish and Game. Boise, ID. USDI Fish and Wildlife Service. 2001. Endangered and threatened wildlife and plants: final rule to list silene spaldingii (Spalding's catchfly) as threatened. Federal Register. 66 (196) 51598-51606. Washington Department of Fish and Wildlife and the Upper Columbia Basin Working Group of Timber, Fish and Wildlife (TFW). 1996. Washington Department of Fish and Wildlife. 1996. Priority Habitats and Species List: Habitat Program. Olympia, Washington. 28p. Washington Fish and Wildlife Commission. 1997. Policy of the Washington Department of Fish and Wildlife and Western Washington Treaty Tribes on Wild Salmonids. Washington Fish and Game Commission, Olympia, WA. 68p. Washington State Department of Fish and Wildlife, 1997. Integrated Streambank Protection, Bank Erosion Assessment and Technique Selection Guidance, Section III, Biological Considerations. Water Quality Standards For Ground Waters of the State of Washington. Chapter 173-200, WAC. Wolff, Jerry 0. 1980. The role of habitat patchiness in the population dynamics of snowshoe hares. Ecological Monographs. 50(1): 111-130. Zim, H. S., A. C. Martin, and A. L. Nelson. 1961. American Wildlife & Plants: A Guide to Wildlife Food Habits. Dover Publications, Inc. New York, NY. 35 Appendix 1 U.S. Fish & Wildlife Service SPOKANE COUNTY Updated 8/29/2015 LISTED Threatened Salvelinus confluentus) (Bull trout) — Columbia River distinct population segment Howellia aquatilis (Water howellia), plant Silene spaldingii (Spalding's silene), plant Spiranthes diluvialis (Ute ladies'-tresses), plant Lynx canadensis (Canada lynx) Coccyzus americanus (Yellow-billed cuckoo) SPECIES OF CONCERN Bald eagle (Haliaeetus leucocephalus) (delisted, monitor status) Burrowing owl (Athene cunicularia) California floater (Anodonta californiensis), mussel Ferruginous hawk (Buteo regalis) Giant Columbia spire snail (Fluminicola columbiana) Loggerhead shrike (Lanius ludovicianus) Long-eared myotis (Myotis evotis) Northern goshawk (Accipiter gentilis) Olive-sided flycatcher (Contopus cooperi) Pallid Townsend's big-eared bat (Corynorhinus townsendii pallescens) Peregrine falcon (Falco peregrinus) (Delisted, monitor status) Redband trout (Oncorhynchus mykiss) Sagebrush lizard (Sceloporus graciosus) Westslope cutthroat trout (Oncorhynchus clarki lewisi) Vascular Plants Haplopappus liatriformis (Palouse goldenweed) M!He. United States Depai tnient of the Interior FISH AND WILDLIFE SERVICE Washington Fish And Wildlife Office 510 Desmond Drive Se, Suite 102 Lacey, WA 98503-1263 Phone: (360) 753-9440 Fax: (360) 753-9405 http://www.fws.gov/wafwo In Reply Refer To: Consultation Code: 01EWFW00-2019-SLI-0368 Event Code: 0 I EWFW00-2019-E-00756 Project Name: Painted Hills PRD Vitali it WCLVIAFE NE-WICK January 29, 2019 Subject: List of threatened and endangered species that may occur in your proposed project location, and/or may be affected by your proposed project To Whom It May Concern: The enclosed species list identifies threatened, endangered, and proposed species, designated and proposed critical habitat, and candidate species that may occur within the boundary of your proposed project and/or may be affected by your proposed project. The species list fulfills the requirements of the U.S. Fish and Wildlife Service (Service) under section 7(c) of the Endangered Species Act (Act) of 1973, as amended (16 U.S.C. 1531 et seq.). New information based on updated surveys, changes in the abundance and distribution of species, changed habitat conditions, or other factors could change this list. The species list is currently compiled at the county level. Additional information is available from the Washington Department of Fish and Wildlife, Priority Habitats and Species website: http://wdfw.wa.gov, mappingiphs/ or at our office website: http: /wwwfws.gov/wafwo/species_new.html. Please note that under 50 CFR 402.12(e) of the regulations implementing section 7 of the Act, the accuracy of this species list should be verified after 90 days. This verification can be completed formally or informally as desired. The Service recommends that verification be completed by visiting the ECOS-IPaC website at regular intervals during project planning and implementation for updates to species lists and information. An updated list may be requested through the ECOS-IPaC system by completing the same process used to receive the enclosed list. The purpose of the Act is to provide a means whereby threatened and endangered species and the ecosystems upon which they depend may be conserved. Under sections 7(a)( I ) and 7(a)(2) of the Act and its implementing regulations (50 CFR 402 et seq.), Federal agencies are required to utilize their authorities to carry out programs for the conservation of threatened and endangered species and to determine whether projects may affect threatened and endangered species and/or designated critical habitat. A Biological Assessment is required for construction projects (or other undertakings having similar physical impacts) that are major Federal actions significantly affecting the quality of the human environment as defined in the National Environrnental Policy Act (42 U.S.C. 4332(2) (c)). For projects other than major construction activities, the Service suggests that a biological evaluation similar to a Biological Assessment be prepared to determine whether or not the project may affect listed or proposed species and/or designated or proposed critical habitat. Recommended contents of a Biological Assessment are described at 50 CFR 402.12. If a Federal agency determines, based on the Biological Assessment or biological evaluation, that listed species and/or designated critical habitat may be affected by the proposed project, the agency is required to consult with the Service pursuant to 50 CFR 402. In addition, the Service recommends that candidate species, proposed species, and proposed critical habitat be addressed within the consultation. More information on the regulations and procedures for section 7 consultation, including the role of pelinit or license applicants, can be found in the "Endangered Species Consultation Handbook" at: http://www.fws.gov/endangered/esa-library/pdf/TOC-GLOS.PDF Please be aware that bald and golden eagles are protected under the Bald and Golden Eagle Protection Act (16 U.S.C. 668 et seq.). You may visit our website at http:,'www.fws.gov/pacifc/ eagle/for information on disturbance or take of the species and information on how to get a permit and what current guidelines and regulations are. Some projects affecting these species may require development of an eagle conservation plan: (http: ''www.fws.gov/windenergy, eagle_guidance.html). Additionally, wind energy projects should follow the wind energy guidelines (http://www.fws.gpv/windenergy) for minimizing impacts to migratory birds and bats. Also be aware that all marine mammals are protected under the Marine Mammal Protection Act (MMPA). The MMPA prohibits, with certain exceptions, the "take" of marine mammals in U.S. waters and by U.S. citizens on the high seas. The importation of marine mammals and marine mammal products into the U.S. is also prohibited. More information can be found on the MMPA website: http: '"www.nmfs.noaa.gov/pr/laws/mmpa/. We appreciate your concern for threatened and endangered species. The Service encourages Federal agencies to include conservation of threatened and endangered species into their project planning to further the purposes of the Act. Please include the Consultation Tracking Number in the header of this letter with any request for consultation or correspondence about your project that you submit to our office. Related website: National Marine Fisheries Service: http://www.nwr.noaa.gov/protected_species/species list/ species_lists.html Attachment(s): • Official Species List 01/29/2019 Event Code: 01EWFW00-2019-E-00756 1 Official Species List This list is provided pursuant to Section 7 of the Endangered Species Act, and fulfills the requirement for Federal agencies to "request of the Secretary of the Interior information whether any species which is listed or proposed to be listed may be present in the area of a proposed action". This species list is provided by: Washington Fish And Wildlife Office 510 Desmond Drive Se, Suite 102 Lacey, WA 98503-1263 (360) 753-9440 Project Summary Consultation Code: 01EWFW00-2019-S1,1-0368 Event Code: 01EWFW00-2019-E-00756 Project Name: Painted Hills PRD Project Type: DEVEI ,OPMENT Project Description: The developer proposes constructing a 580 unit planned residential development. The project was planned for construction two years ago, and will be built as soon as permitted in 2019-2020. Project Location: Approximate location of the project can be viewed in Google Maps: https:// www.google.corrilmaps/place/47.616722714208315N117.2421334615195W Counties: Spokane, WA 01/29/2019 Event Code: 01EWFVV00-2019-E-00756 Endangered Species Act Species There is a total of 4 threatened, endangered, or candidate species on this species list. Species on this list should be considered in an effects analysis for your project and could include species that exist in another geographic area. For example, certain fish may appear on the species list because a project could affect downstream species. IPaC does not display listed species or critical habitats under the sole jurisdiction of NOAA Fisheries1, as USFWS does not have the authority to speak on behalf of NOAA and the Department of Commerce. See the "Critical habitats" section below for those critical habitats that lie wholly or partially within your project area under this office's jurisdiction. Please contact the designated FWS office if you have questions. 1. NOAA Fisheries, also known as the National Marine Fisheries Service (NMFS), is an office of the National Oceanic and Atmospheric Administration within the Depai Intent of Commerce. Birds NAME STATUS Yellow-billed Cuckoo Coccyzus americanus Population: Western U.S. DPS There is proposed critical habitat for this species. Your location is outside the critical habitat. Species profile: https://ecos.fws.goviecp/species/3911 Threatened Fishes NAME STATUS Bull Trout Salvelinus confluentus Threatened Population: U.S.A., conterminous, lower 48 states There is final critical habitat for this species. Your location is outside the critical habitat. Species profile: https://ecos.fivs,gov/ecp/species/8212 01/29/2019 Event Code: 01EWFW00-2019-E-00756 4 Flowering Plants NAME STATUS Spalding's Catchfly Silene spaldingii Threatened No critical habitat has been designated for this species. Species profile: https://ecos.fws.gov/ecp/species/3681 Water Howellia Howellia aquatilis No critical habitat has been designated for this species. Species profile: https://ecos.fws.gov/ecp/species/7090 Critical habitats Threatened THERE ARE NO CRITICAL HABITATS WITHIN YOUR PROJECT AREA UNDER THIS OFFICE'S JURISDICTION. Appendix 2 Critical Areas Maps 47° 37 26"N 4P 36' 28" N 3 48.0400 4614 413!300 mr-serawiewmar Soil Map—Spokane County, Washington isectco 441C41 462200 4@2500 gar li 483IC, A3 E 44t h•Ave--7 E47tivAv, JP • " F • my 'At • • . • .4( • L . ," ypOti14:44•; 4- .6 • . 7170 d i • • ,. • 1 '; 1 ' -1200 -74,04z, #r-1080 Uri VeWay d '1030 &Thor peeRct 3.130 ' Ave , \ 5073 r.-~„i 5041 .-/ (5 040 j (. 3022 3054 4 4230400 3 I 4807230 481000 481300 Map ceal.: 1:12,700 If printed on A landscape (11" x 8.5") sheet. 481600 Meters 0 150 300 600 900 Feet 0 500 1000 2030 3000 Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: MN Zone UN WGS84 I I 1 7 481900 482200 482500 482800 483100 3 §) S USDA Natural Resources Web Soil Survey 4/1/2015 re a Conservation Service National Cooperative Soil Survey Page 1 of 3 47' 377e N 47. 35' 38'N Soil Map—Spokane County, Washington MAP LEGEND MAP INFORMATION Area of Interest (A01) Spoil Area The soil surveys that comprise your A01 were mapped at 1:24,000. ---' Area of Interest (A01) , Stony Spot Please rely on the bar scale on each map sheet for map Soils Stony Sp measurements. Very ot . _1 Soil Map Unit Polygons Source of Map: Natural Resources Conservation Service Wet Spot ..,-0 Soil Map Unit Lines Web Soil Survey LPL: http://websoilsurvey.nrcs.usda,gov Other Coordinate System: Web Mercator (EPSG:3857) a Soil Map Unit Points ... Special Line Features Maps from the Web Soil Survey are based on the Web Mercator Special Point Features projection, which preserves direction and shape but distorts Water Features Q Blowout distance and area. A projection that preserves area, such as the Streams and Canals Albers equal-area conic projection, should be used if more accurate 27 Borrow Pit calculations of distance or area are required. Transportation X Clay Spot +-i-t Rails This product is generated from the USDA-NRCS certified data as of ,,.5 Closed Depression ....• Interstate Highways the version date(s) listed below. , US Routes Gravel Pit Soil Survey Area: Spokane County, Washington Gravelly Spot Survey Area Data: Version 5, Sep 4, 2014 Major Roads Soil map units are labeled (as space allows) for map scales 1:50,000 Landfill Local Roads or larger. A. Lava Flow Background Date(s) aerial images were photographed: Jun 4, 2011—Jul 5, ,11 Marsh or swamp is Aerial Photography 2011 ":•L Mine or Quarry The orthophoto or other base map on which the soil lines were Miscellaneous Water compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting Perennial Water of map unit boundaries may be evident. Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot t Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 4/1/2015 Page 2 of 3 Soil Map—Spokane County, Washington Map Unit Legend Spokane County, Washington (WA063) Map Unit Symbol Map Unit Name Acres in A01 Percent of A01 1040 Hardesty ashy silt loam, 0 to 3 percent slopes 14.4 2.3% 1080 Narcisse silt loam, 0 to 3 percent slopes 108.4 17.7% 1200 Endoaquolls and Fluvaquents, 0 to 3 percent slopes 61.9 10.1% 3022 Bong ashy sandy loam, moist, 0 to 8 percent slopes 14.3 2.3% 1.2% 3054 Clayton ashy fine sandy loam, 0 to 8 percent slopes 7.2 3130 Phoebe ashy sandy loam, 0 to 3 percent slopes 29.2 4.8% 5040 Spokane-Swakane complex, 3 to 15 percent slopes 7.9 1.3% 5041 Spokane-Swakane complex, 15 to 30 percent slopes 43.1 7.0% 5073 Lenz-Rock outcrop complex, 15 to 30 percent slopes 37.6 6.1% 7101 Pits-Dumps complex 12.0 2.0% 7110 Urban land-Opportunity, disturbed complex, 0 to 3 percent slopes 11.4 1.9% 7122 7170 Urban land-Marble, disturbed complex, 8 to 15 percent slopes 0.1 0.0% Urban land-Springdale, disturbed complex, 0 to 3 percent slopes 153.0 24.9% 7181 Urban land-Phoebe, disturbed complex, 3 to 8 percent slopes 112.9 18.4% 100.0% Totals for Area of Interest 613.5 usDA Natural Resources Web Soil Survey 4/1/2015 -ilia Conservation Service National Cooperative Soil Survey Page 3 of 3 I -N. IlwfaS•nAorall,./.1t1 U.S. Fish and Wildlife Service National Wetlands inventory May 14, 2015 a. age 11! • 19, e'r a e 1 • V12 ; .19211114•CI 1 rt. Wetlands Freshwater Emergent INS Freshwater Forested/Shrub Estuarine and Marlene Deepwater Hilln 4 Estuarine and Marine Freshwater Pond Lake 41a. Rivarine Other of • A ti ow, 1 '14 ru. .41 User Remarks: -46111'?" • 4 ri POIF MD MY esri This map Is for general reference only. TM US Fish and Wildlife Service Is not responsible for the accuracy or currentness of the base data shown on this map. All wetlands related data should be used in accordance with the tither methdata found on the Wetlands Mapper web elle. A10 we. -ktiul hydrolv 6->-1 Wor a. cc.aefieivi.e/, • \ I -r; 0 u " a WHIM AMU '41‘ L I MN e; , as yirriCtli1 jort, V- I 1 61. IVA 0 loll gqiit ta L pirmiur preggirirr iiipoimtuoimpp jitlipprif ..1.8111711ttanfIMITIMMIUMATF 1. 1.111./.1114...1 fiLLUIS affifILEL43. 1.1a.> lattatf u ajtalt. r Wpm glItFIR IIIRPF.177r9,41111 ' PRIV' 49 4"1 rirgliffr 11:AFFIFF.19 '9411 11 tii,:trIALLALLAAA,',41,,,g,Liti bilgii: ,; lvliqvH 111°!Jci SITE ELEMENT PLAN Sheet C1.3 UNDERGROUND SERVICE ALERT ONE—CALL NUMBER - SETTLING POND INFILTRATION - POND II S DRAIN GE; EASEMENT TO BE AL ERD AT FINAL PLAT two cc CHESTER CREEK EXISTING BOX CULVERT CHESTER CREEK 24 100' STREAM BUFFER-- CHESTER CR. BOX dAAPHIE SCALE 15.,1 4mm00 200 goo 200 1 ( IN FEET ) 1 Inch = 200 ft. DATUM: NAVD - 88 TBM S-5 OF THE SOUTH PONDEROSA SEWER PROJECT WITH AN ELEVATION OF 2005.87 (NAVD29)=2009.67 (NAVD88) WAS USED FOR THE VERTICAL DATUM FOR THIS MAP. STORAGE AREA #1 2-48" RCP , CONVEYANCE EXISTING LEVEE 100' STREAM BUFFER CULVERT EXTENSION ROADSIDE SWALE (TYPIC 2-48" RCP CONVEYANCE TEMPORARY DRAINAGE EASEMENT EXISTING LEVEE STREAM BUFFER IMPACT MITIGATION AREA TEMP. DRAINAGE EASEMENT CHESTER CREEK 40TH AVENUE BIOSWALE HEADWALL ROADSIDE SWALE (TYPICAL) 18" CULVERT 18" CULVERT 18" CULVERT 2-48" RCP CONVEYANCE " CULVERT 2-48" RCP CONVEYANCE LL STORAGE AREA #6 SEE GUSTIN PIPE PLAN SET FOR MORE DETAILS EXISTING 36"CULVERT 811 Call. IIUSNESS DAYS WINE YOU 010 TRIANGLE POND INFILTRATION FIELD SEE GUSTIN PIPE PLAN SET FOR MORE DETAILS EXISTING GROUND FUTURE TRACT/BORDER UTILITY EASEMENT 28' I Am ROW 30' 10' MEANDERING PATH 16' ROADSIDE SWALE PROPOSED 2-48" RCP PIPE MADISON RD EASEMENT PLAN NOT TO SCALE CONCRETE CHANNEL 3 EXISTING 15" CMP CULVERTS TO BE REMOVED THORPE RD BOX CULVERT 30'W X 3'H BOX CULVERT 2 013-14-16 JPP REVISED PLANS 1 06-12.16` JPP ORIGINAL PREPARATION .I DA SCALE: HORIZONTAL: I" = 200' VERTICAL: N/A PROJ #: DATE: DRAWN: REVIEWED: City of Spokane Valley Project/Permit No.: SUB-2010-0001 (Subdivision) FPD-2016-0007 (Flood Plain Development) EGR-2016.0066 (Engineered Grading) City of Spokane Valley Development Engineering se. street 110$ - Num q Not Reviewed Reviewed for Conformance to &met standards and Accepted per chapter la Date Accepted Acceptance Comments PLANS NOT APPROVED BY AGENCY 13-1166 X CNIL STRUCTURAL - SPOKANE VALLEY PAINTED HILLS PRD 06/14/18 JPP SURVEYING ~WCE SITE ELEMENT PLAN DISHMAN-MICA RD. TRAFFIC PLANNING WHIPPLE CONSULTING ENGINEERS 2528 NORTH SULLIVAN ROAD LANDSCAPE TRW OTHER SPOKANE VALLEY, WA 99216 PH:509-893.2017 FAX 609.928-022/ SPOKANE VALLEY,WA 5462 o C2( SHEET 01.3 JOB NUMBER 13-1166 100 Year Flood Event Thorpe Road Crossing 64 cfs with Channel South of Thorpe 91 cfs without Channel South of Thorpe Madison Hills Flow to Culverts 15 cfs through 4 - 18" Culverts Gustin Pipe Flow to Triangle Pond 16 cfs through 36" Culvert under Highway 27 Ben Goodmansen From: Ken Puhn <kpuhn@westconsultants.com> Sent: Monday, July 16, 2018 8:37 AM To: Ben Goodmansen Subject: requested info for Painted Hills Ben, Per our conversation you had requested confirmation of water surface elevations in the vicinity of the Madison culverts and also the flood discharges entering your facilities. The 100-year water surface elevations calculated by our XPSWMM model within the Madison pipes are shown in the table below. The 100-yr discharges are shown in the 2' table below. Note that the levee breach discharge came down slightly once I had the final design in the model. Let me know if you need anything else. Ken Node Max 100-yr WSE Pipe_Inlet 2009.49 SDMH 1B 2008.30 SDMH 1A 2008.12 SDMH 2A 2007.61 SDMH 2B 2007.86 SDMH 3B 2006.51 SDMH 3A 2006.14 SDMH 4B 2005.64 SDMH 5B 2004.63 SDMH 4A 2004.11 SDMH 6B 2003.99 SDMH 5A 2003.81 Pipe_Outlet 2003.71 US of Spreader 2003.72 Location 100-yr (cfs) 100-yr levee breach (cfs) Gustin Ditch Downstream of Hwy 27 16 n/a Golf Course Overflow @ Thorpe 64 91 Golf Course Overflow plus Madison hills inflows 79 106 1 System Capacity Box Culvert Capacity 216.4 cfs @ 2 ft of depth, 1 ft of Freeboard Madison Mainline Pipe Capacity 154.32 cfs & 3.8 ft of depth Bio Filtration Channel 269.86 cfs @ 6 ft of depth Channel Report Hydraflow Express Extension for Autodeskt AutoCAD8 Civil 3D: by Autodesk. Inc. Box Culvert Capacity Rectangular Highlighted Thursday, Jun 7 2018 Bottom Width (ft) = 28.33 Depth (ft) = 2.00 Total Depth (ft) = 3.00 Q (cfs) = 216.40 Area (sqft) = 56.66 Invert Elev (ft) = 1000.00 Velocity (ft/s) = 3.82 Slope (%) = 0.50 Wetted Perim (ft) = 32.33 N-Value = 0.040 Crit Depth, Yc (ft) = 1,22 Top Width (ft) = 28.33 Calculations EGL (ft) = 2.23 Compute by: Q vs Depth No. Increments = 30 1\1 fi e. -k-CePA 5 14\ vo.f ki, Rock 1', mok -TotrA344 TA‘etsiAcx Elev (ft) Section Depth (ft) 1004.00 1003.00 1002.00 1001 00 1000 00 - 999.00 4 00 3.00 2.00 0 5 10 15 20 25 30 35 40 1.00 0.00 -1.00 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk6AutoCADO Civil 3D® by Autodesk, Inc. Madison Pipe (1- 48 in Pipe) Tuesday, Jun 19 2018 Circular Highlighted Diameter (ft) = 4.00 Depth (ft) = 3.80 Q (cfs) = 77.16 Area (sqft) = 12.34 Invert Elev (ft) = 1000.00 Velocity (ft/s) = 6.25 Slope (%) = 0.25 Aro -7-..?bie V-41 Wetted Perim (ft) = 10.78 N-Value = 0.013 Sg.‘ Crit Depth, Yc (ft) = 2.66 Top Width (ft) = 1.73 Calculations EGL (ft) = 4.41 Compute by: Q vs Depth No. Increments = 20 PIPE rt n x FL 0,-/ ?Zioe MAr Ft 04/= !S.-4672 e4,5 Elev (ft) Depth (ft) Section 1005.00 5.00 1004.00 4.00 1003.00 3.00 1002.00 2.00 1001.00 1.00 1000.00 0.00 999.00 1.00 0 1 2 3 4 5 6 Reach (ft) Channel Report Hydrafiow Express Extension for Autodesk®AutaCADS Civil 3D® by Autodesk, Inc Bioswale Capacity Trapezoidal Highlighted Thursday, Jun 7 2018 Bottom Width (ft) = 6.00 Depth (ft) = 6.00 Side Slopes (z:1) = 3.00, 3.00 Q (cfs) = 269.86 Total Depth (ft) = 6.00 Area (sqft) = 144.00 Invert Elev (ft) = 1000.00 Velocity (Ws) = 1.87 Slope (%) = 1.00 Wetted Perim (ft) = 43.95 N-Value = 0.175 Crit Depth, Yc (ft) = 2.64 Top Width (ft) = 42.00 Calculations EGL (ft) = 6.05 Compute by: Q vs Depth No. Increments = 20 Elev (ft) 1007.00 1006.00 1005.00 1004.00 1003.00 1002.00 1001.00 1000.00 999 00 Section Depth (ft) 7.00 6.00 5.00 4.00 3.00 2.00 1.00 0.00 -1.00 0 5 10 15 20 25 30 35 40 45 50 55 Reach (ft) Storage and Discharge Pond Summary Worksheet Settling Pond Infiltration Pond Emergency Park Storage GRAVEL GALLERY WORKSHEET - NORTH Outflow 162.64 cfs — Storage Volume 109,805 cf WHIPPLE CONSULTING ENGINEERS POND VOLUME CALC SHEET Project: 13-1166 FLOOD PONDS Designer: PP Volume to Bioswale Outlet Date: 6/19/2018 Treatment Storutre Ponds Bottom Area sf Squared Side If Pond Bottom Elevation at Drywell Pond Drywell Elevation Pond Inlet Elevatior (avg) Conic Volume to Rim cf Side Slope Volume cf Total Volume to to Rim cf Conic Volume to Inlet cf Side Slope Volume cf Total Volume to Inlet cf STORAGE 61,004 247 1995.80 1996.80 1997.80 61,004 1,482 62,486 122,008 5,928 127,936 *SETTLING 7.172 85 1996.80 1996.80 1997.80 0 0 0 7,172 508 7,680 Total 68,176 62,486 135,616 *Assumes portion of Bioswale to reach a depth of I' but does not include additional volume Volume to Pipe Inlet Ponds Bottom Area sf Squared Side If Pond Bottom Elevation at Drywell Pond Drywell Elevation Pond Inlet Elevation (avg) Conic Volume to Rim cf Side Slope Volume cf Total Volume tc to Rim cf Conic Volume to Inlet cf Side Slope Volume cf *Total Volume to Inlet cf STORAGE 61,004 247 1995.80 1996.80 2000.24 61,004 1,482 62,486 270,858 29,214 300,072 SETTLING 7,172 85 1996.80 1996.80 2000.24 0 0 0 24,672 6,013 30,685 Total 68,176 _ 62,486 330,757 *Does not include additional storage prov ded by Bioswale Emergency Park Storage Ponds Bottom Area sf Squared Side If Pond Bottom Elevation at Drywell Pond Drywell Elevation Pond Inlet Elevation (avg) Conic Volume to Rim cf Side Slope Volume cf Total Volume to to Rim cf Conic Volume to Inlet cf Side Slope Volume cf *Total Volume to Inlet cf Rim 176,181 420 2006.00 _ is 2007.00 2011.00 176,181 12,518 178,699 880,905 62,961 943,866 at-ft = 4.10 21.67 WHIPPLE CONSULTING ENGINEERS GRAVEL GALLERY CALC SHEET 5/15/2018 13-1166 Painted Hills PRD ENGINEER JPP Note: infiltration rates per IPEC Geotechnicat Report Dated December 31, 2013 Gallery Depth (Min) Porosity of Gravel (Typ) Infiltration Rate ft cf/cf cfsisf 10 0.3 f 1.80E-03 4 0.3 1.80E-03 Gallery Number of Galleries Length Width Ground Water EL. Gravel Gallery Bott. EL Volume Storage Volume Perimeter Sidewall Area Bottom Area Outflow ft ft ft_ ft cf cf ft sf sf cis CONTACT AREA 1 246.99 246.99 - - 244016 73205 988 3,952 61,004 116.92 A 1 280.00 10.00 - - 28,000 8,400 580 5,800 0 10.44 B 1 280.00 10.00 - - 28,000 8,400 580 5,800 0 10.44 C 1 280.00 10.00 - - 28,000 8,400 580 5,800 0 10.44 D 1 280.00 10.00 .. - 28,000 8,400 580 5,800 0 10.44 E 1 100.00 10.00 - - 10,000 3,000 220 2,200 0 3.96 Totals 109,805 162.64 *Note: Btm Area = Gallery Area - Contact Area Storage Volume = Volume* Porosity Sidewall Area= PerimeterDepth OutFlow = Sidewall Area+ Bottom Area * Infiltration Rate Note: Outflow Assumes a Full Gallery BIO-FILTRATION CHANNEL WORKSHEET 79 cfs With Channel South of Thorpe 83% of treatment achieved 106 cfs Without Channel South of Thorpe 69% of treatment achieved Open- Channel Hydraulics, Chow (reference) Bio-filtration Swale Design Based on King County 2005 Surface Water Design Manual (Section 6.2 and 6.3) Modified to model flow of flood water utilizing reference Open Channel Hydraulics. CHOW Design Flow: Q„ = 79.00 cfs With channel south of Thorpe Calculation of swale depth Q = 1.49 A R`' "S`" Manning's equation OR b = CL„, n,„ (1.49 67s0 OR Y =10,„ n,„ (1.49"b * SC' 5).116 Ow, where b QWQ = S = width known: b = 6.00 ft S = 0.010 ftift n„ = 0.175 y = 5.17 ft Determining design flow velocity: V„ = Q„ r A„, max 1.0 fps where V,„ = A„ = b'y + Z*y' A,„ = Z = Z= 2 A„ = 111.10 sf = 0.71 fps bottom width of swale (ft)..,minimum 2 ft width required, maximum 10 ft = water quality design flow (cfs) Manning's roughness coefficient for vegetal retardance conditions (CHOW) design flow depth longitudinal slope (along direction of flow) (ft/ft). slope shall be between 1%-6%. If less than 1.5%, underdrains must be provided. Slope less than 1% is considered a "wet biofiltration swale" and must be designed under those guidelines. Slope greater than 6% requires check dams with vertical drops of 12-inches design flow velocity (fps) cross-sectional area of flow at design depth (sf) side slope length per unit height (e.g. for 3:1. Z Calculate swale length to achieve a minimum hydraulic residence time of 9 minutes (540 seconds): L = 540 " V . minimum swale length is 100 ft L = 383.98 ft Calculation to verify n - value Per Table on page 182 of Open-Channel Hydraulics Area Wp Rh V 111.10 38.68 2.87 VRh =VR 0.71 2.04 n - plot 0.175 Channel Report Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Bioswale @79 cfs Trapezoidal Highlighted Bottom Width (ft) = 6.00 Depth (ft) = 5.17 Side Slopes (z:1) = 3.00, 3.00 Q (cfs) = 190.65 Total Depth (ft) = 6.00 Area (sqft) = 111.08 Invert Elev (ft) = 1000.00 Velocity (ftls) = 1.72 Slope (%) = 1.00 Wetted Perim (ft) = 38.68 N-Value = 0.175 Crit Depth, Yc (ft) = 2.22 Top Width (ft) = 37.00 Calculations EGL (ft) = 5.21 Compute by: Q vs Depth No. Increments = 36 Tuesday, Jun 19 2018 D41 671 Vfi 6IA p ftirmv Elev (ft) Section Depth (ft) 7,00 1007.00 6,00 1006.00 1005.00 5.00 4.00 1004.00 1003.00 3.00 2.00 1002.00 1001.00 1.00 0.00 1000.00 999.00 -1.00 0 5 10 15 20 25 30 Reach (ft) 35 40 45 50 55 Bio-filtration Swale Design Based on King County 2005 Surface Water Design Manual (Section 6.2 and 6.3) Modified to model flow of flood water utilizing reference Open Channel Hydraulics. CHOW Design Flow: 106.00 cfs Without channel south of Thorpe Calculation of swale depth = 1.49 A R°67Sc Manning's equation OR b = Q„, (1.49* yl 675'5) where b = bottom width of swale (ft)...minimum 2 ft width required, ' maximum 10 ft OR Ow, = water quality design flow (cfs) Manning's roughness coefficient for vegetal retardance Y [Q„ n„., (1 49 * b °S i]C 6 11,w4 = conditions (CHOW) y = design flow depth S = longitudinal slope (along direction of flow) (ftift), slope shall width known: b = 6.00 ft be between 1%-6%. If less than 1.5%, underdrains must S = 0.010 ft/ft be provided. Slope less than 1% is considered a "wet nwq = 0.130 biofiltration swale" and must be designed under those guidelines. Slope greater than 6% requires check dams y = 5.16 ft with vertical drops of 12-inches Determining design flow velocity: V,„ = Q„ A„, max 1.0 fps A„ = ry ° Z= where V„ = design flow velocity IPS ) = cross-sectional area of flow at design depth (sf) Z = side slope length per unit height (e.g. for 3:1. Z = 3) A„= 123.80 sf = 0.86 fps Calculate swale length to achieve a minimum hydraulic residence time of 9 minutes (540 seconds): L = 540 ' V„, minimum swale length is 100 ft L = 462.36 ft Calculation to verify n - value Per Table on page 182 of Open-Channel Hydraulics Area Wp Rh V 123.80 38.63 3,20 VRh =VR 0.86 2.74 n - plot 0.175 Channel Report Hydraflow Express Extension for Autodesk i AutoCADr . Civil 3DP3 by Autodesk, Inc Bioswale @ 106 cfs Trapezoidal Highlighted Tuesday. Jul 17 2018 Bottom Width (ft) = 6.00 Depth (ft) = 5.16 Side Slopes (z:1) = 3.00, 3.00 Q (cfs) = 255.89 Total Depth (ft) = 6.00 Area (soft) = 110.84 Invert Elev (ft) = 1000,00 Velocity (ft/s) = 2.31 Slope (%) = 1.00 Wetted Perim (ft) = 38.63 N-Value = 0.130 Crit Depth, Yc (ft) = 2.57 Top Width (ft) = 36.96 Calculations EGL (ft) = 5.24 Compute by: Q vs Depth No. Increments = 50 Elev (ft) 1007.00 1006.00 1005.00 1004 00 1003.00 1002.00 1001.00 1000.00 999.00 Section 0 5 10 15 20 25 30 35 40 45 50 55 Depth (ft) 7.00 6.00 5.00 4.00 3.00 2.00 1.00 0.00 -1.00 Reach (ft) OPEN-CHANNEL HYDRAULICS YEN TE CHOW, Ph.D. Professor of Hydraulic Engineering University of Illinois McGRAW-HILL BOOK COMPANY New York Toronto London 1959 184 v TABLE 7-5. GUIDE IN SELECTION OF VEGETAL RETARDANCE* Stand Average length of grass, in. Degree of retardance Good >30 11-24 6-10 2-6 <2 A Very high B High C Moderate D Low E Very low Fair >30 11-24 6-10 2-6 <2 B High C Moderate D Low D Low E Very low * U.S. Soil Conservation Service [41]. 7-18. The Permissible Velocity. The permissible velocity of flow in a grassed channel is the velocity that will prevent severe erosion in the channel for a reasonable length of time. Permissible velocities for differ- ent vegetal covers, channel slopes, and soil conditions, recommended on the basis of investigation by the Soil Conservation Service, are shown in Table 7-6. 7-19. Selection of Grass. The selection of grass for the channel lining depends mainly on the climate and soil in which the plant will grow and survive under the given conditions. From the hydraulic viewpoint, stability and other factors should also be considered. In general, a higher discharge requires a stronger or better lining. On steep slopes, bunch grasses, such as alfalfa, lespedeza, and kudzu, will develop channel- ing of the flow and, hence, are unsatisfactory for lining. For slopes greater than 5%, only fine and uniformly distributed sod-forming grasses, such as Bermuda grass, Kentucky bluegrass, and smooth brome, n-re recommended for lining where the main flow occurs. Because of the objectionable spreading nature of sod-forming grasses, the top portion of the sides and the berm may be planted with grasses that do not spread easily, such as weeping love grass. For fast establishment of the lining, Bermuda grass and weeping love grass are recommended. Sometimes annuals are used as temporary protection until permanent covers by native grasses are established. Silt deposition in channels may be con- trolled by lining with bunch grasses, which will develop channeled flow, increase velocity, and thus reduce silting. 7-20. Procedure of Design. After the kind of grass for channel lining is selected, the degree of retardance can be determined from the condition of the stem length and the density of growth. During the period of DESIGN OF CHANNELS FOR UNIFORM FLOW 185 itiblishment, the grass will grow and the channel will be stabilized under a ndition of low degree of retardance. The channel will not reach its intLxinium capacity until the grass cover is fully developed and well irablished. Therefore, it is suggested that the hydraulic design of a grassed channel consist of two stages. The first stage (A) is to design the channel for stability, that is, to determine the channel dimensions under the condition of a lower degree of retardance. The second stage TABLE 7-6. PERMISSIBLE VELOCITIES FOR CHANNELS LINED WITH GRASS* Cover Slope range, Permissible velocity, fps Erosion-resistant soils Easily eroded soils rmuds grass 0-5 5-10 >10 8 7 6 6 5 4 Buffalo grass, Kentucky bluegrass, smooth brome, blue grama 0-5 5-10 >10 7 6 5 5 4 3 Grass mixture 0-5 5 5-10 4 Do not use on slopes steeper than 10% 3 Lespedeza sericea, weeping love grass, ischaemum (yellow blue- stem), kudzu, alfalfa, crabgrass 0-5 3.5 2.5 Do not use on slopes, steeper than 5%, except for side slopes in a combination channel Iffnuals—used on mild slopes or as 0-5 I 3.5 2.5 ',temporary protection until per- Use on slopes steeper than 5% is not recom- manent covers are established, mended common lespedeza, Sudan grass REMA.RES. The values apply to average, uniform stands of each type of cover. Use velocities exceeding 5 fps only where good covers and proper maintenance can be stained. * U.S. Soil Conservation Service [41]. jE) is to review the design for maximum capacity, that is, to determine thQ increase in depth of flow necessary to maintain a maximum capacity 1/nd(.1 the condition of a higher degree of retardance. For instance, if Enimon lespedeza is selected as the grass for lining, the common lespedeza of low vegetal retardance (green, average length 4.5 in.) is used for the first stage in design. Then, in the second stage, the common lespedeza of moderate vegetal retardance (green, uncut, average length 11 in.) o' 1d be used. Finally, a proper freeboard is added to the computed OPEN clieuviva lirdnia“ 182 UNIFORM FLOW .o .6 .5 .4 .3 .2 _ . ).13 ... ...-- • ......-•----- -- ....--' ...sok...0 ... '.'"''''. . I------" ..„....---•...--•-''-'' :- _ WEEPING LOVEGRASS GREEN,2ND AVE. LENGTH SEASON 30" -T .. ..,. .46.,. . .„2.,,;,.. .1 .03 .06 .05 .04 .03 .02 • - .- r. ....„.:::....., ISC EMUM L C,....„.„..... SEASON 36 ......... 1ST LENGTH GREEN, AVE. AVERAGE - (A) . .2 .3 .4 .5 .6 .8 . I ..-•-••. 2 4013 4 5 6 B 10 20 & .8 .6 V R (a) Curves for A or ver h vegetal retardance. 1 1 1 BERMUDA GRASS I I GREEN, AVE LENGTH le Geotechnical Reports Triangle Pond Infiltration (Storage Area 6) IPEC Proposed Stormwater Pond dated October 14, 2014 North Pond Location Boring IPEC Supplemental Geotechnical Evaluation dated April 19, 2016 Pavement Design (Public Roads) IPEC Geotechnical Evaluation — Proposed Street Improvements dated June 26, 2017 Full-Scale Drywell Testing IPEC Full-Scale Drywell Testing dated August 21, 2017 IPEC Addendum to Full-Scale Drywell Testing dated August 22, 2017 Mounding Analysis IPEC Mounding Analysis dated August 22, 2017 REPORT 2 Geotechnical Evaluation, Proposed Stormwater Pond, dated October 14, 2014 IPEC Inland Pacific Engineering Company Geotechnical Engineering and Consulting October 14. 2014 Project No. 14-086 NAI Black cio Mr. Bryan Walker 107 South Howard Suite 500 Spokane, WA 99201 Re: Geotechnical Evaluation Proposed Stormwater Pond Parcel No. 45343.9052 Spokane Valley. WA Dear Mr. Walker: As you authorized, we have completed a geotechnical evaluation for geotechnical evaluation at the above-referenced site in Spokane Valley, Washington. The purpose of our services is to evaluate the subsurface soil and groundwater conditions relative to use as a stormwater management facility as part of the Painted Hills golf course property stormwater management system, This report summarizes the results of our site investigation, engineering analyses and recommendations. PROJECT DESCRIPTION We understand that the proposed project may consist of a residential development. The site consists of 91 acres currently developed as a golf course. Stonnwater runoff will be treated using drvwells and/or gravel galleries for subsurface infiltration. These type of facilities will also be used to manage potential floodwaters. if needed. To account for stormwater runoff volumes from the unnamed tributary along State Highway 27. you propose to use this parcel as a stormwater pond with drvwells for subsurface infiltration. P.O. Box 1566, Veradale, WA 99037 Phone 509-209-6262 Geotechnical Evaluation Proposed Stormwater Pond Spokane County, WA Inland Pacific Engineering Company Project No. 14-086 Parcel No. 45343.9052 October 14, 2014 Page 2 AVAILABLE INFORMATION We were provided a conceptual site plan for the project by Whipple Consulting Engineers, Inc. (WCE). This plan showed the proposed pond limits, proposed and existing ground surface elevation contours, and property lines. This plan was prepared by WCE and was not dated. FIELD EVALUATION Procedures A geotechnical engineer from Inland Pacific Engineering Company (IPEC) observed the excavation of four test pits at the site. The test pits were excavated on October 1, 2014 using a rubber-tired backhoe operated by an independent firm working under subcontract to IPEC. The geotechnical engineer from IPEC observed the test pit excavations and logged the surface and subsurface conditions. Ground surface elevations at the test pits were interpolated from the contours shown on the site plan. The soils encountered in the test pits were visually and manually classified in the field by our field personnel in accordance with ASTM D 2488, "Description and Identification of Soils (Visual- Manual Procedures)". The samples were returned to our facility for review of the classification by a geotechnical engineer and laboratory testing. Soils Encountered The test pist encountered glacially deposited silty sand at the surface overlying poorly graded sands to the termination depths of the test pits. Groundwater was not encountered in the test pits during or after excavation. Well log data in the vicinity of the site indicate that groundwater levels range from approximately 90 to 100 feet. Geologic maps indicate the soils in this area consist primarily of glacially deposited sands and gravels. According to the Soil Survey of Spokane County, the site soils are classified as Urban land-Springdale, disturbed complex. These soils are described as somewhat excessively drained soils that formed in sandy and gravelly glaciofluvial deposits with minor amounts of volcanic ash and loess in the upper part. The native soils exposed in the test pits were consistent with the NRCS data. Laboratory Testing We performed grain size analysis tests on samples obtained from the test pits. The tests were performed in accordance with ASTM Method of Test D 6913. The results of the tests performed are attached to this report. Geotechnical Evaluation Proposed Stormwater Pond Spokane County, WA Inland Pacific Engineering Company Project No. 14-086 Parcel No. 45343.9052 October 14, 2014 Page 3 ANALYSIS AND RECOMMENDATIONS Stormwater Recommendations Based on the data obtained from the test pits, field permeability test, and laboratory tests performed, it is our opinion that swales and drywells would be suitable for infiltration of stormwater. We estimated a design outflow rate for drywells using the results of the laboratory tests and the procedures described in the SRSM manual, Appendix 4A (Spokane 200 Method). The following table summarizes the results of the analysis. Test Pit Depth (feet) USCS Classification Percent Fines Normalized Outflow Rate (cfs/ft) Recommended Design Drywell Outflow Rate (cfs) Type A Type B TP-1 10 — 12 SP 1.0 0.5 0.3 1.0 TP-2 10 — 12 SP 1.5 0.5 0.3 1.0 TP-3 10 — 12 SP 1.4 0.5 0.3 1.0 TP-4 10 — 12 SP 1.6 0.5 0.3 1.0 These recommended design outflow rates include a safety factor of 1.3 as required by the SRSM. REMARKS This report is for the exclusive use of the addressee and the copied parties to use in design of the proposed project and to prepare construction documents. In the absence of our written approval, we make no representations and assume no responsibility to other parties regarding this report. The data, analyses, and recommendations may not be appropriate for other structures or purposes. We recommend that parties contemplating other structures or purposes contact us. Services performed by the geotechnical engineers for this project have been conducted in a manner consistent with that level of care ordinarily exercised by members of the profession currently practicing in this area under similar budget and time restraints. No warranty, expressed or implied, is intended or made. Geotechnical Evaluation Proposed Stermwater Pond Spokane County, WA Inland Pacific Engineering Cornpan Project No. 14-086 Parcel No. 45343.9052 October 14. :014 Page 4 GENERAL REMARKS It has been a pleasure being of service to you for this project. If you have any questions or need additional information, please do not hesitate to call me at (509) 209-6262 at your convenience. Sincerely, Inland Pacific Engineering Company Paul T. Nelson, P.E. Principal Engineer Attachments: Figure 1, Site Location Map Figure 2, NRCS Map Figure 3, Test Pit Location Map Logs of Test Pits TP- I through TP-4 Descriptive Terminology Laboratory Test Results T N 0 WAS 0 /4,h,e‘• w0 (N .9k. 228 ,c) 6)&1 G/STV*" ONAL tel-M-14( FIGURE 1 — ' • M I r . t—rT'14—f .r - 3 -, I. J -ILI' 11, - i 1--P l' ' g r • 11 ; — iei 41' .! i :. k - 6 .... I 6. .0 , ' ' ' . 42,...'' t i.'-' ', a ..-' ii- e3 ' ■ i —v-..4.,. ,-.,...- .4'co.(-- e. ../ , a ... ..i2V: ..4 .4%4_, & 11 IA -,,,•.,.657 , 'Ik,:, •. • ,ip.:-.''" . -41 / ' .,..,_ , 4, J. r-',' ---zi;:- . A F' ' /! / 'ItR IV •Pr'''''' f I • a "L. $6,11". • / /- 411; • ar,.1! _2 4.1:4 rf)%." ■ ■ '1 • 4 • I I SITE 0 11 a Li C; e1 o o g . IPEC Inland Pacific Engineering Company Geotechnical Engineering and Consulting Site Location Map Project No. 14-086 Proposed Stormwater Pond Parcel No. 45343.9052 Spokane County, WA October 9, 2014 FIGURE 2 '4Ssti / Ti LT_ SITE ••• IMC11010id 411/4 ; • to! yr; •••• • IPEC Inland Pacific Engineering Company Geotechnical Engineering and Consubing NRCS Map Project No. 14-086 Proposed Stormwater Pond Parcel No. 45343.9052 Spokane County, WA October 9, 2014 FIGURE 3 r - -- 1,, / // -- .......,-------. ---- ---...----:,---,...4..s-- \ •..„...„:„....,..,..., , 1. .....Z)110..,% \ \\\\\ \\ ,/ \\i,k1 \ /Molk \ 4/ illki \IN / 7 1 '‘10\v ! / 1 \\O\ ..,C ...-"Y‘ *1z.,,,, f' I///fr ___ ,- A 1 ,-\\ -,---4 '-'' —\ * ... :•-•.' -,--,„..,-- . (0/1,- :, 4 1;-1 1 Ilin \ ter -,.. xx„.\\:, ilk ... ,N. \ ,,. .... \ • ) i ',... t • - " \\\V-) -_ -..... -Z \* \'\ / .... -_ , __ ....„.., ,.., ........, -....', \':',.. \ `,•,‘"\\`' \ / / ...." --. .....". ..,,, \ .\\‘‘, '1,v. ...*-- , \ N,\?..,..NNKI,N. -,,,,......\\ -,;;.N,:••• - '''<, „, I /* ..- '%70„ ••.. \N.- • \ / \ ; 1 \\\.1-1rly‘kiI,A.W,,,, )1...,,Ael,,,,,iirti TP-1 • TP-2. I • .1, I° TP43 ,, / Iiiiirr P I I S40.,„ ,..., „. tit ,,,...„:„,,....,4!..:.p,-,.t 4 .....--., ..... , 4 , ./i 'N...N.%* ....."....Z.• 01,....:,•-. .1.9.417: N.. 11 ...• , • \ • ;...,-, N `,:,'.`..q .)1 . .S.."7:;7-- -..---=,•-.....--- I; I Test Pit Location Map IPEC Project No. 14-086 October 9, 2014 Proposed Stormwater Pond Parcel No. 45343.9052 Spokane County, WA Inland Pa cifc Engmeenng Company Geoteelnkal Engineering and Conndting IPEC LOG OF TEST PIT Inland Pacific Engineering Company Geotechnical Engineering and Consulting PROJECT: 14-086 Geotechnical Proposed Parcel No. Spokane 'TEST PIT: TP-1 Evaluation LOCATION: See Test Pit Location Stormwater Pond Map 45343.9052 County, WA DATE: 10/1/14 SCALE: 1"=2' ELEV. 1994.5 DEPTH 0.0 ASTM 02487 Symbol DESCRIPTION OF MATERIALS WL TESTS OR NOTES 1993.5 1.0 SM SILTY SAND WITH GRAVEL, fine to coarse grained, brown, moist. (Glacial Outwash) 1979.5 15.0 SP POORLY GRADED SAND WITH GRAVEL, medium to coarse grained, with Cobbles, brown, moist. (Glacial Outwash) End of test pit. Groundwater not encountered. Test pit immediately backfilled. LOG OF TEST PIT IPEC Inland Pacific Engineering Company Geotechnical Engineering and Consulting I PROJECT: 14-086 Geotechnical Evaluation Proposed Stormwater Pond Parcel No. 45343.9052 Spokane County, WA TEST PIT: TP-2 LOCATION: See Test Pit Location Map DATE: 10/1/14 SCALE: 1"7--21 ELEV, 1994,5 DEPTH 0.0 ASTM D2487 Symbol DESCRIPTION OF MATERIALS WL TESTS OR NOTES 1993.0 1.5 SM SILTY SAND WITH GRAVEL, fine to coarse grained, brown, moist. (Glacial Outwash) 1979.5 15.0 SP POORLY GRADED SAND WITH GRAVEL, medium to coarse grained, with Cobbles, brown, moist. (Glacial Outwash) End of test pit. Groundwater not encountered. Test pit immediately backfilled. LOG OF TEST PIT IPEC Ina/ld Pacific 1141nm:ins Comp any Geotechnical Engineering and Consulting PROJECT: 14-086 Geotechnical Proposed Stormwater Parcel No. Spokane County, TEST PIT: TP-3 Evaluation LOCATION: See Test Pit Location Pond Map 45343.9052 WA ,DATE: 10/1/14 SCALE: 1"=2' ELEV. 1995 DEPTH 0.0 ASTM D2487 Symbol DESCRIPTION OF MATERIALS WL TESTS OR NOTES 1994 1.0 SM SILTY SAND WITH GRAVEL, fine to coarse grained, brown, moist. (Glacial Outwash) 1980 15.0 SP POORLY GRADED SAND WITH GRAVEL, medium to coarse grained, with Cobbles, brown, moist. (Glacial Outwash) End of test pit. Groundwater not encountered. Test pit immediately backfilled. LOG OF TEST PIT IPEC Inland Pacific Engineering Company Geote clinical Engineering and Consulting PROJECT: 14-086 Geotechnical Proposed Stormwater Parcel No. Spokane County, !TEST PIT: TP-4 Evaluation *LOCATION: See Test Pit Location Pond Map 45343.9052 WA jDATE: 10/1/14 SCALE: 1".2' ELEV. 1996 DEPTH 0.0 ASTM D2487 Symbol DESCRIPTION OF MATERIALS WL TESTS OR NOTES 1995 1981 1.0 15.0 SM SILTY SAND WITH GRAVEL, fine to coarse grained, brown, moist. (Glacial Outwash) SP POORLY GRADED SAND WITH GRAVEL,medium to coarse grained, with Cobbles, brown, moist. (Glacial Outwash) End of test pit. Groundwater not encountered. Test pit immediately backfilled. i IPEC Inland Pacific Engineenng Cornisam. Geote chime al Engine enng and Consulting RELATIVE DENSITY OR CONSISTENCY VERSUS SPT N-VALVE COARSE-GRAINED SOILS FLNE-GRAINED SOILS DENSITY N(BLOWS/FT) CONSISTENCY N(BLOWS/FTi Very Loose 0 - 4 Very Soft 0 - 1 Loose 4 - 10 Soft 2 - 3 Medium-Dense 11 - 30 Rather Soft 4 - 5 Medium 6 - 8 Dense 31 - 50 Rather Stiff 9 - 12 Stiff 13 - 16 Very Dense > 50 Very Stiff 17 - 30 Hard > 30 USCS SOIL CLASSIFICATION MAJOR DIVISIONS GROUP DESCRIPTIONS Coarse- Grained Soils <50% passes #200 sieve Gras el and Gra\ elly Soils <50q coarse fraction passes #4 sieve Graff el _ . .. , OW Well Graded Gravel GP Poorly Graded Gravel Gras el :,.:;. ,:.-.: %,..., GM Silty Gravel GC Clayey Gravel Sandy and Sandy Soils >50ci coarse fraction passes #4 sieve Sand -, , ,. . SW Well Graded Sand SP Poorly Graded Sand Sand ,,,,,i.,,: , n,,,,, SM Silty Sand SC Clayey Sand Fine- Grained Soils >50% passes #200 sie‘e Silt and Clay Liquid Limit < 50 ML CL OL Silt Lean Clay Organic Silt and Clay (lov. plasticity) Sall and Clay Liquid Limit > 50 MH CH OH Inorganic Silt Fat Clay Organic Clay and Silt , med ti• high pliitii:it i Highly Organic Soils PT Peat Muck MODIFIERS DESCRIPTION RANGE Occasional <5% Trace 5% - 12% With >12% MOISTURE CONTENT DESCRIPTION FIELD OBSERVATION Dry Absence of moisture, dusty, dry t ) the touch Moist Dry' of optimum moisture content Wet ,, Wet of optimum moisture content MAJOR DIVISIONS WITH GRAIN SIZE SIEVE SIZE 12'. 3" 3/4" 4 10 40 200 GRAIN SIZE (INCHES ) 12 3 0.75 0.19 0.079 0.0171 0.0029 Boulders Cobbles Gravel Sand Silt and Ciay Coarse Fine Coarse Medium Fine 3" 3/4" #4 #10 #20 #40 #100 #200 100.0 0 n a S S n 9 90.0 80.0 70.0 60.0 50.0 40.0 30.0 20.0 10.0 0.0 100 10 GRAIN SIZE (mm) 01 0.01 100 0.001 UNIFIED SOIL CLASSIFICATION COARSE FINE COARSE MEDIUM FINE FINES SYSTEM GRAVEL GRAVEL SAND SAND SAND Sample Identification: L14-039 Sample Description: SP Poorly Graded Sand with Gravel 10 20 30 40 50 60 70 80 90 e n R a n e d Lab No. • L14-039 IPEC Inland Pacific Engineering Company Creoteehnical Engineering and Consulting .0 Box 1,1 i_limmoontr,_ WA 99037 209-6262 GRAIN SIZE REPORT Cl 40th Avenue Stormwater TP-1 @ 10-12' hill No.: Date: 14-086 10/1/2014 3" 3/4" #4 #10 #20 #40 #100 #200 100.0 0 P C e n P a n 9 90.0 80.0 70.0 60.0 50.0 40.0 30.0 20.0 10.0 0.0 100 10 GRAIN SIZE (mm) 01 0.01 100 0.001 UNIFIED SOIL CLASSIFICATION COARSE FINE COARSE MEDIUM FINE FINES SYSTEM GRAVEL GRAVEL SAND SAND SAND Sample Identification: L14-040 Sample Description: SP Poorly Graded Sand with Gravel 10 20 30 40 50 60 70 80 90 P e e n R a n d Lab No. L14-040 .0 Box 1 IPEC Inland P2 cific Engineering Company Geotechrucal Engineering and Consulting fr,3-.0 WA 99037 209-6262 _ GRAIN SIZE REPORT ."oluci• 40th Avenue Stormwater Location: TP-2 © 10-12' IA No.: 14-086 IDate: 10/1/2014 100.0 90.0 80.0 P e 70.0 e n 60.0 50.0 P a S 40.0 S n 30.0 9 20.0 10.0 0.0 3" 3/4" #4 #10 #20 #40 #100 #200 100 10 GRAIN SIZE (mm) 01 0.01 100 0.001 UNIFIED SOIL CLASSIFICATION COARSE FINE COARSE MEDIUM FINE FINES SYSTEM GRAVEL GRAVEL SAND SAND SAND r Sample Identification: L14-041 Sample Description: SP Poorly Graded Sand with Gravel 0 10 20 30 40 50 60 70 P? PO P a R e a n e d Lab No. L14-041 IPEC Inland Pacific Engineering Company Geotechnical Engineering and Consulting P.O Box 1566, Veradale, WA 99037 (509) 209-6262 GRAIN SIZE REPORT Project: 40th Avenue Stormwater Location: TP-3 CO 10-12' Job No.: 14-086 Date: 10/1/2014 P e e n a S n 9 3/4' #4 #10 #20 #40 #100 #200 100.0 I 90.0 80.0 70.0 60.0 50.0 40.0 30.0 20.0 10.0 0.0 # is 100 10 GRAIN SIZE (mm) 01 0.01 100 0.001 UNIFIED SOIL CLASSIFICATION COARSE FINE COARSE MEDIUM FINE FINES SYSTEM GRAVEL GRAVEL SAND SAND SAND Sample Identification: L14-042 Sample Description: SP Poorly Graded Sand with Gravel 0 10 20 30 40 50 60 70 80 90 e C n e a n d Lab No. L14-042 IPEC Inland Pacific F-nginetimg Company Geotechnical Engineering and Consulting P.O Box 1566, Veradale, WA 99037 (509) 209-6262 GRAIN SIZE REPORT Project: 40th Avenue Stormwater Location: TP-4 @ 10-12' Job No.: 14-086 Date: 10/1/2014 Royal Myhre From: Gorman, Connie <Connie.Gorman@avistacorp.com> Sent: Wednesday, March 06, 2019 10:53 AM To: Royal Myhre Subject: RE: [External] SEWER-WATER-STREETS-GAS-POWER-PHONE-CABLE PLANS FOR 19-2320 Attachments: Pittsburg and Rosewood - ELECT.pdf; Pittsburg and Rosewood - GAS.pdf Here you go!! From: Royal Myhre [mailto:royalm@whipplece.com] Sent: Wednesday, March 06, 2019 10:22 AM To: AITOR LACAMBRA (AITOR.LACAMBRA@CENTURYLINK.COM) <AITOR.LACAMBRA@CENTURYLINK.COM>; BRYAN RICHARDSON (BRYAN RICHARDSON@CABLE.COMCAST.COM) <BRYAN RICHARDSON@CABLECOMCAST.COM>; Gorman, Connie <Connie.Gorman@avistacorp.com>; TIM NASH (TNASH@SPOKANECITY.ORG) <TNASH@SPOKANECITY.ORG> Subject: [External] SEWER-WATER-STREETS-GAS-POWER-PHONE-CABLE PLANS FOR 19-2320 TO ALL, WE ARE DOING A PROJECT ON THE NORTH WEST CORNER OSF PITTSBURG AND ROSEWOOD WE WOULD LIKE TO GET THE ABOVE PLANS FOR OUR PROJECT THANK YOU ALL FOR YOUR HELP Royal Myhre Engineering Tech, Whipple Consulting Engineers, Inc. Phone: 509.893.2617 I Fax: 509.926.0227 AWC E Whipple Consulting Engineers WCE provides Land Development services in the following areas. Land Surveying, Civil. Structural and Traffic Engineering. Land Planning and Landscape Architecture. 21 South Pints Road • Spokane Valley. WA 99206 WhlopteCE coin EnD 1 USE CAUTION - EXTERNAL SENDER Do not click on links or open attachments that are not familiar. For questions or concerns, please e-mail phishing@avistacorp.com CONFIDENTIALITY NOTICE: The contents of this email message and any attachments are intended solely for the addressee(s) and may contain confidential and/or privileged information and may be legally protected from disclosure. If you are not the intended recipient of this message or an agent of the intended recipient, or if this message has been addressed to you in error. please immediately alert the sender by reply email and then delete this message and any attachments. 2 REPORT 8 Supplemental Geotechnical Evaluation, dated April 19, 2016 IPEC Inland Pacific Engineering Company Geotechnical Engineering and Consulting April 19, 2016 Project No. 16-249 NAI Black cio Mr. Bryan Walker 107 South Howard Suite 500 Spokane, WA 99201 Re: Supplemental Geotechnical Evaluation Painted Hills Golf Course Property 4403 South Dishman-Mica Road Spokane Valley, WA Dear Mr. Walker: As you authorized, we have completed the supplemental geotechnical evaluation for the Painted Hills Golf Course property at the above-referenced site in Spokane Valley, Washington. The purpose of the supplemental evaluation is to provide additional soil and groundwater data to address concerns of the City of Spokane Valley. This report summarizes the results of our field investigation, laboratory testing, engineering analyses, and our opinions and recommendations for stormwater management. PROJECT DESCRIPTION We understand that the proposed project may consist of a residential development. The site consists of 91 acres currently developed as a golf course. Stonnwater runoff will be treated using diywells and/or gravel galleries for subsurface infiltration. These type of facilities will also be used to manage potential floodwaters, if needed. This supplemental evaluation is intended to provide additional subsurface data at the north end of the site to assist in identifying areas where subsurface infiltration of stormwater may be feasible due to the presence of suitable soils at depth. P.O. Box 1566, Veradale, WA 99037 Phone 509-209-6262 Supplemental Geotechnical Evaluation Painted Hills Golf Course Property Spokane Valley, WA Inland Pacific Engineering Company Project No. 16-249 Parcel No. 45344.9108 April 19, 2016 Page 2 AVAILABLE INFORMATION We were provided a topographic survey for the project site by Whipple Consulting Engineers, Inc. (WCE). This topographic survey showed the existing roadways, existing structures, property lines, and existing ground surface elevation contours. This plan was prepared by WCE and was dated November 7, 2013. The site was used as a golf course prior to our evaluation. The site is relatively level with some elevated golf greens and excavated areas for water hazards. The site is primarily grass-covered with scattered trees along the fairways and pine trees in the undeveloped area to the northwest. The clubhouse building is present at the southwest corner. In addition, we performed a preliminary geotechnical evaluation for the property in December 2013. The results of that evaluation, along with our opinions and recommendations, are summarized in our Preliminary Geotechnical Evaluation dated December 31, 2013. We also performed a geotechnical evaluation for certification of the existing levee along Chester Creek in April 2014. The results of that evaluation are summarized in our Geotechnical Evaluation report dated February 12, 2015. Lastly, we performed a geotechnical evaluation in July 2015 consisting of ten 50-foot borings in the south half of the property. The results of that evaluation are summarized in our Geotechnical Evaluation Phase 2 report dated July 23, 2015. FIELD EVALUATION Procedures A geotechnical engineer from Inland Pacific Engineering Company (IPEC) observed the drilling of three penetration test borings at the site. The borings were drilled between March 17 and 19, 2016 using a truck-mounted drill operated by an independent firm working under subcontract to IPEC. A geotechnical engineer or engineering assistant from IPEC observed the borings and logged the surface and subsurface conditions. After we logged the borings, they were abandoned in accordance with state requirements. Ground surface elevations at the borings were provided by WCE. The soils encountered in the borings were visually and manually classified in the field by our field personnel in accordance with ASTM D 2488, "Description and Identification of Soils (Visual- Manual Procedures)". The samples were returned to our facility for review of the classification by a geotechnical engineer and laboratory testing. Supplemental Geotechnical Evaluation Painted Hills Golf Course Property Spokane Valley, WA Inland Pacific Engineering Company Project No. 16-249 Parcel No. 45344.9108 April 19, 2016 Page 3 Soils Encountered In general, the borings encountered 2 feet of topsoil at the surface. Below the topsoil, the borings generally encountered glacially-deposited silty to clayey sands and/or gravels overlying poorly graded sands to termination depths of the borings. The clayey sands and gravels were generally encountered in the upper 12 to 18 feet. Penetration resistances in the sands and gravels ranged from 15 to 90 blows per foot (BPF) and averaged 37 BPF, indicating that these soils were medium dense to very dense, but were typically dense. Geologic maps indicate the soils in this area consist primarily of alluvial and/or glacially deposited silts, clays, sands, and gravels. According to the Soil Survey of Spokane County, the site soils are classified by the Natural Resource Conservation Service (NRCS) as Hardesty ashy silt loam, Narcisse silt loam, Endoaquolls and Fluvaquents, Phoebe ashy sandy loam, and Urban land-Springdale disturbed complex. The native soils encountered in the borings were consistent with the NRCS data. Groundwater was encountered in Boring B-2 at a depth of 71 feet. This depth corresponds to an elevation of 1934.6. Groundwater was not encountered in the remaining borings. The observed water levels further indicates that groundwater levels drop generally from south to north with higher levels near Chester Creek. Fluctuations in the groundwater level may occur due to rainfall, flooding, irrigation, spring thaw and other seasonal and annual factors not evident at the time the observations were made. ANALYSIS, OPINIONS, AND RECOMMENDATIONS Based on the data obtained from the recent and previous borings, previous test pits, field permeability tests, and laboratory tests performed, it is our opinion that subsurface infiltration of stormwater is feasible. The most promising layers are the glacial sands and gravels. These soils would be suitable for infiltration using standard drywells. We will perform a mounding analysis for the drywells after the proposed full-scale drywell test is completed to assess down-gradient impacts REMARKS This report is for the exclusive use of the addressee and the copied parties to use in design of the proposed project and to prepare construction documents. In the absence of our written approval, we make no representations and assume no responsibility to other parties regarding this report. The data, analyses, and recommendations may not be appropriate for other structures or purposes. We recommend that parties contemplating other structures or purposes contact us. Supplemental Geotechnical Evaluation Painted Hills Golf Course Property Spokane Valley, WA Inland Pacific Engineering Company Project No. 16-249 Parcel No. 45344.9108 April 19, 2016 Page 4 Services performed by the geotechnical engineers for this project have been conducted in a manner consistent with that level of care ordinarily exercised by members of the profession currently practicing in this area under similar budget and time restraints. No warranty, expressed or implied, is intended or made. GENERAL REMARKS It has been a pleasure being of service to you for this project. If you have any questions or need additional information, please do not hesitate to call me at (509) 209-6262 at your convenience. Sincerely, Paul T. Nelson, P.E. Principal Engineer Attachments: Figure 1, Site Location Map Figure 2, NRCS Map Figure 3, Boring Location Map Logs of Borings B-1 through 8-3 Descriptive Terminology Laboratory Test Results ‘k.. N 4,s, 0 i ,9 37228 • ( S €0/STE9*",,0 SIGN N' cc FIGURE 1 AVAIL . ' 441116.4 • - , 3 • . f`f • 404 N a oil 411L 11. SITE C.> 2013 Go_og Site Location Map II2 Project No. 16-249 April 19, 2016 Painted Hills Golf Course 4403 South Dishman-Mica Road Spokane County, WA Inland Pacific Engineering Company Geoteclmical Engineering and Consulting FIGURE 2 > - - Cl.a.r • - -r. . te - ' r* ' All ...,* • . - ? 1 . ;. • 3 iit'''' ‘ M, • r i i 'lid o 111 I Tlri.r. ... ..- .•r , .,.../. ,v ,-.- 1, , c- -. it 4 r I . L . (;11, ir 6,•• I- ..' , r' .. .1. $1 • •r- i • , ..al, • -) , - t".. ' _, '•;.• . '",..-i 11! .' '' - ., • ., .- _ -1, 41 1 11:Fil? .),Irreagler ,r rl 7,1) .rr.il n ,r - Iffirl ijk ) .. ,I. :.------------------ 4040 .C• 1'200\ 7101 1080 SITE Ott. riOipoltd • •J ,••• 3430 5073f I 0041 5041( 3054 F NRCS Map IPEC Project No. 16-249 April 19, 2016 Painted Hills Golf Course 4403 South Dishman-Mica Road Spokane County, WA Inland Pacific Engineering Company Geotechnical Engineering and Consulting FIGURE 3 ----- e'., / I I i 1 I I\ •\x i --• --C. , I I I Li) -- ZGRiszas-j— aT ammo— :x II MEWL♦ on 0 amawr ) ' • ..1 Rif • .1! , ITMIRMITIPwa ele 4 11,11111111111111•11s ---- B-3 es, Boring Location Map IPEC Project No. 16-249 April 19, 2016 Painted Hills Golf Course 4403 South Dishman-Mica Road Spokane County, WA Inland Pacific Engineering Company Geotechnical Engineering and Consulting LU CD zz w z a. 7 z cr, (14 0 0 LU 0 0 C0 0 0 co z cC LU Inland C 3012 Spokane IPE Telephone: Pacific Engineering Company BORING NUMBER B-1 North Sullivan Road, Suite C Valley, WA 99216 509-209-6262 PAGE 1 OF 2 509-290-5734 PROJECT NAME Painted Hills Supplemental CLIENT PROJECT DATE DRILLING DRILLING LOGGED NOTES Fax: NAI Black NUMBER STARTED CONTRACTOR METHOD BY 16-249 PROJECT LOCATION 4403 South Dishman-Mica Road 3/17/16 COMPLETED Drilling 3/17/16 GROUND ELEVATION 2005,9 ft HOLE SIZE 8 inches Johnson Exploration GROUND WATER LEVELS: Hollow Stem Auger AT TIME OF DRILLING — Not encountered PRF CHECKED BY PTN AT END OF DRILLING — Not encountered AFTER DRILLING -- Not encountered o DEPTH (ft) SAMPLE TYPE NUMBER TESTS . c5 cn: D GRAPHIC LOG MATERIAL DESCRIPTION Fines = 7% sm L.: .• .. ‘, , 2.0 (SM) SILTY SAND, fine to medium grained, with roots, dark brown, moist. (Topsoil) 2003.9 SP- SM ' 17.0 ‘ (SP-SM) POORLY GRADED SAND with SILT, medium to coarse grained, a trace of Gravel, brown, moist, medium dense. (Glacial Outwash) 1988.9 ss 10 SS 15 SS r _ 20 SP SS (SP) POORLY GRADED SAND with GRAVEL, medium to coarse grained, brown, moist, very dense to medium dense. (Glacial Outwash) SS 25 30 SS (Continued Next Page) 0_ z - CD CD O 111 H z H LLJ LL h:2L 0 0 CD LU O - 0 IL q 07 < (l; 7 H H B CD 0 IPEC CLIENT NAI Black Inland Pacific Engineering Company 3012 North Sullivan Road, Suite C Spokane Valley, WA 99216 Telephone: 509-209-6262 Fax: 509-290-5734 PROJECT NUMBER 16-249 BORING NUMBER B-1 PAGE 2 OF 2 PROJECT NAME Painted Hills Supplemental PROJECT LOCATION 4403 South Dishman-Mica Road a LU w >-1/ w 2 2z Coco TESTS MATERIAL DESCRIPTION 35 40 X SS 45 50 SS c. 7 SS SS SP 50.5 (SP) POORLY GRADED SAND with GRAVEL, medium to coarse grained, brown, moist, very dense to medium dense. (Glacial Outwash) (continued) 1955.4 End of boring. Groundwater not encountered with 49' of hollow-stem auger in the ground. Groundwater not encountered immediately after withdrawal of the auger. Bore hole then abandoned. S SUPPLEMENTALGPJ z H 2 9) 0 LLI 0 0_ 0 in H O ‘`)i ft Cc IPEC Inland Pacific Engineering Company 3012 North Sullivan Road, Suite C Spokane Valley, WA 99216 Telephone: 509-209-6262 Fax: 509-290-5734 BORING NUMBER B-2 PAGE 1 OF 3 CLIENT NAI Black PROJECT NAME Painted Hills Supplemental PROJECT NUMBER 16-249 PROJECT LOCATION 4403 South Dishman-Mica Road DATE STARTED 3/17/16 COMPLETED 3118/16 GROUND ELEVATION 2005.6 ft HOLE SIZE 8 inches DRILLING CONTRACTOR Johnson Exploration Drilling GROUND WATER LEVELS: DRILLING METHOD Hollow Stem Auger AT TIME OF DRILLING -- Not encontered LOGGED BY PRF CHECKED BY PTN AT END OF DRILLING 71.00 ft I Elev 1934.60 ft NOTES 7 AFTER DRILLING 73.50 ft i Elev 1932.10 ft 0-1.1.1 5 10 SS 15 s 20 S 25 X SS 30 SS S LLJ Z < mo z(.0 TESTS U_I 0a0 CD sm ;kt; s2.0 SC 6.5 12-33 45 GC 24-20 (44) 12.0 24-29 (53) 25-28 (53) SP 10-18 Fines = 8% (28) 11-13 (24) MATERIAL DESCRIPTION (SM) SILTY SAND, fine to medium grained, with roots, dark brown, moist. (Topsoil) 2003.6 (SC) CLAYEY SAND with GRAVEL, medium to coarse grained, brown, moist to wet, dense. (Glacial Outwash) 1999.1 (GC) CLAYEY GRAVEL with SAND, fine to coarse grained, brown, moist, dense. (Glacial Outwash) 1993.6 (SP) POORLY GRADED SAND with GRAVEL, medium to coarse grained, a trace of Cobbles, brown, moist, very dense to medium dense. (Glacial Outwash) (Continued Next Page) co uJ co LU 1p z LU LU H o_ H IPEC Inland Pacific Engineering Company 3012 North Sullivan Road, Suite C Spokane Valley. WA 99216 Telephone: 509-209-6262 Fax: 509-290-5734 BORING NUMBER B-2 PAGE 2 OF 3 CLIENT NAI Black PROJECT NAME Painted Hills Supplemental PROJECT NUMBER 16-249 PROJECT LOCATION 4403 South Dishman-Mica Road LLJ 0 TESTS SCS a Jo MATERIAL DESCRIPTION 35 40 S 28-37 (65) 45 SS 50/5' S 1 50/5" -C3 0_ 0)H _ 0 55 - LUc0 z- 8 (7 Ci 60 65 50/5' SS 8-17 (25) SP (SP) POORLY GRADED SAND with GRAVEL, medium to coarse grained, a trace of Cobbles. brown, moist, very dense to medium dense. (Glacial Outwash) (continued) (Continued Next Page) PPLEMENTAL GINT I 16-249 PAINTED HILLS SUPPLEMENTAL.GPJ 6 - J:\ IPEC PROJECTS \ 2016 PROJECTS419-249 PAI I WELL GINT STD US L AELGDT - 4/5/16 1 IPEC Inland Pacific Engineering Company 3012 North Sullivan Road, Suite C Spokane Valley, WA 99216 Telephone: 509-209-6262 Fax: 509-290-5734 BORING NUMBER B-2 PAGE 3 OF 3 CLIENT NAI Black PROJECT NAME Painted Hills Supplemental PROJECT NUMBER 16-249 PROJECT LOCATION 4403 South Dishman-Mica Road 7 0_ 1.1.1 UJ 0 CO 0 > D < TESTS 1E1 21-11 32) SP E 0 0 0 MATERIAL DESCRIPTION (SP) POORLY GRADED SAND with GRAVEL, medium to coarse grained, a trace of Cobbles, brown, moist, very dense to medium dense. 31 (Glacial Outwash) (continued) 75.0 1.930.6 End of boring. Groundwater encountered at 71' with 75' of hollow-stem auger in the ground. Goundwater encountered at 73.5' 10 minutes later. Groundwater not encountered to cave-in depth of 15' immediately after withdrawal of the auger. Bore hole then abandoned. al r. ra. CL S V) CoH a Co ti z :2LL.1 0.1 0- 0 0_ rn Co Co Co O Co w H 0) 0 cn Inland IPEC 3012 Spokane Telephone: Pacific Engineering Company BORING NUMBER B-3 North Sullivan Road, Suite C Valley, WA 99216 509-209-6262 PAGE 1 OF 2 509-290-5734 PROJECT NAME Painted Hills Supplemental CLIENT PROJECT DATE DRILLING DRILLING LOGGED NOTES Fax: NAI Black NUMBER STARTED CONTRACTOR METHOD BY 16-249 PROJECT LOCATION 4403 South Dishman-Mica Road 3/18/16 COMPLETED Drilling 3/19/16 GROUND ELEVATION 2004.5 ft HOLE SIZE 8 inches Johnson Exploration GROUND WATER LEVELS: Hollow Stern Auger AT TIME OF DRILLING -- Not encountered PRF CHECKED BY PTN AT END OF DRILLING -- Not encountered AFTER DRILLING --- Not encountered c) DEPTH (ft) SAMPLE TYPE NUMBER TESTS vi cifc_.5 ?1 GRAPHIC LOG MATERIAL DESCRIPTION - Fines = 6% ML I, , i; • oo Nk 2.0 (ML) SANDY SILT, with roots, dark brown, moist. (Topsoil) 2002.5 GC 8.0 (GC) CLAYEY GRAVEL with SAND, fine to coarse grained, brown, moist, dense. (Glacial Outwash) 1996.5 SS _ - 10 SC 12.0 (SC) CLAYEY SAND with GRAVEL, medium to coarse grained, brown, moist to wet, dense. (Glacial Outwash) 1992.5 SS _ _ 15 GC 18.0 (GC) SILTY CLAYEY GRAVEL with SAND, fine to coarse grained, brown, moist, medium dense. (Glacial Outwash) 1986.5 SS - 20 SP (SP) POORLY GRADED SAND with GRAVEL, medium to coarse grained, a trace of Cobbles, brown, moist, very dense to medium dense. (Glacial Outwash) 1 SS 25 SS 30 kx / SS r \ (Continued Next Page) IPEC Inland Pacific Engineering Company 3012 North Sullivan Road, Suite C Spokane Valley, WA 99216 Telephone: 509-209-6262 Fax: 509-290-5734 BORING NUMBER B-3 PAGE 2 OF 2 CLIENT NAI Black PROJECT NAME Painted Hills Supplemental PROJECT NUMBER 16-249 PROJECT LOCATION 4403 South Dishman-Mica Road 0-LU TESTS 6. L vR U_ 0 CD MATERIAL DESCRIPTION 35 2 o_ O r- - a 40 z c, O5 C-C_ TD US LAB.GDT CD 2 S SS 50 SS SS SP 50.5 (SP) POORLY GRADED SAND with GRAVEL, medium to coarse grained, a trace of Cobbles, brown, moist, very dense to medium dense. (Glacial Outwash) (continued) 1954.0 End of boring. Groundwater not encountered with 49' of hollow-stem auger in the ground. Groundwater not encountered immediately after withdrawal of the auger. Bore hole then abandoned. IPEC Inland Pacific Engineering Company Geotechnic al Engineering and Consulting RELATIVE DENSITY OR CONSISTENCY VERSUS SPT N-VALVE COARSE-GRAINED SOILS FINE-GRAINED SOILS DENSITY N(BLOWS/FT) CONSISTENCY N(BLOWS/FT) Very Loose 0 - 4 Very Soft 0 - 1 Loose 4 - 10 Soft 2 - 3 Medium-Dense 11 - 30 Rather Soft 4 - 5 Medium 6 - 8 Dense 31 - 50 Rather Stiff 9 - 12 Stiff 13 - 16 Very Dense > 50 Very Stiff 17 - 30 Hard > 30 USCS SOIL CLASSIFICATION MAJOR DIVISIONS GROUP DESCRIPTIONS Coarse- Grained Soils <50% passes #200 sieve Gravel and Gravelly Soils <50% coarse fraction passes #4 sieve Gravel is,i, Link ., a, fino) GW Well Graded Gravel GP Poorly Graded Gravel Gravel is,iria >12% fines) GM Silty Gravel GC Clayey Gravel Sandy and Sandy Soils >50% coarse fraction passes #4 sieve Sand n.iiisiinkor.c..0 SW Well Graded Sand SP Poorly Graded Sand Sand (with >ii% som) SM Silty Sand SC Clayey Sand Fine- Grained Soils >50% passes #200 sieve Silt and Clay Liquid Limit < 50 ML CL OL Silt Lean Clay Organic Silt and Clay (low plasticity) MB Salt and Clay CH Liquid Limit > 50 OH Inorganic Silt Fat Clay Organic Clay and Silt (med to high plasticity) Highly Organic Soils PT Peat Muck MODIFIERS DESCRIPTION RANGE Occasional <5% Trace 5% - 12% With >12% MOISTURE CONTENT DESCRIPTION FIELD OBSERVATION Dry Absence of moisture, dusty, dry to the touch Moist Dry of optimum moisture content Wet Wet of optimum moisture content MAJOR DIVISIONS WITH GRAIN SIZE SIEVE SIZE 12" 3" 3/4" 4 10 40 200 GRAIN SIZE (INCHES) 12 3 0.75 0.19 0.079 0.0171 0.0029 Boulders Cobbles Gravel Sand Silt and Clay Coarse Fine Coarse Medium Fine Inland Pacific Engineering Company GRAIN SIZE DISTRIBUTION IPEC 3012 North Sullivan Road, Suite C Spokane Valley, WA 99216 Telephone: 509-209-6262 Fax: 509-290-5734 CLIENT NAI Black PROJECT NAME Painted Hills Supplemental PROJECT NUMBER 16-249 PROJECT LOCATION 4403 South Dishman-Mica Road U.S. SIEVE OPENING IN INCHES 6 4 3 2 1.5 1 I U.S. SIEVE Nur, BERS I HYDROMETER ' 1/2318 3 4 6 810 14 16 20 30 40 50 60 100 140 200 100 1 I I I I II 11 I I I I 95 90 it 3.\\85 80 _ 75 70 \H 65 i L.0 iir,TL 60 )- 55 cc cc w 50 1 \ \ \ t \ EZ 1\ \ H 45 z LU (--) \ \ 1 1 CC 40 LLJ o_ 1 \ \ 35 1 \ 30 25 1 \ \\ 20 15 \\ \ ., 10 _1 5 0 100 10 1 GRAIN SIZE IN 0.1 0.01 0.001 MILLIMETERS GRAVEL SAND COBBLES coarse fine coarse medium fine SILT OR CLAY BOREHOLE DEPTH Classification l LL PL PI Cc Cu • B-1 30.0 _ SP-SM Poorly Graded Sand with Silt 1.37 8.65 I B-2 25.0 SP-SM Poorly Graded Sand with Silt 1 , 2.10 8.72 • B-3 30.0 SP-SM Poorly Graded Sand with Silt 1.85 1 9.95 1 BOREHOLE DEPTH D100 D60 D30 D10 %Gravel %Sand %Silt %Clay • B-1 30.0 19 2.679 1.065 0.31 21.9 71.2 6.8 X B-2 25.0 19 1.992 0.977 0.228 13.9 77.9 8.2 • B-3 30.0 19 4.708 2.032 0.473 39.7 54.1 6.2 W I J> ) 00 LU z 05 0 u_ u.; co O cc 8 re ,73 Inland Pacific Engineering Company GRAIN SIZE DISTRIBUTION IPEC 3012 North S Sullivan Road. Suite C pokane Valley, WA 9921 Telephone: 509-209-62626 Fax: 509-290-5734 CLIENT NAI Black PROJECT NAME Gustin Levee PROJECT NUMBER 14-037B PROJECT LOCATION Spokane County U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS I HYDROMETER 6 4 3 2 1 5 1/2318 3 4 6 810 14 16 20 30 40 50 60 100 140 200 100 I I I I I I I I . 95 90 85 80 75 70 65 H m CD w 60 >- 55 co et w 50 Z TL H 45 z w II° 40 w 0 35 30 25 20 15 10 5 0 100 10 1 GRAIN SIZE IN 0 1 0.01 0.001 MILLIMETERS GRAVEL SAND SILT OR CLAY COBBLES coarse fine coarse medium fine BOREHOLE DEPTH Classification LL PL PI Cc Cu • TP-3 3.5 SM Silty Sand with Gravel I TP-5 4.0 SM Silty Sand • TP-6 4.0 SM Silty Sand with Gravel BOREHOLE DEPTH D100 D60 D30 D10 %Gravel %Sand %Silt %Clay • TP-3 3.5 25 2.902 0.336 30.4 47.8 21.8 I TP-5 4.0 19 1 0.179 12.6 38.9 48.5 • TP-6 4.0 37.5 3.959 0.195 36.9 37.6 25.4 -----; REPORT 10 Geotechnical Evaluation, Proposed Street Improvements (Pavement Design) dated June 26, 2017 U IPEC Inland Pacific Engineering Company Geotechnical Engineering and Consulting June 26, 2017 Project No. 16-249D Mr. Bryan Walker NAI Black 107 S Howard Suite 500 Spokane, WA 99201 Re: Geotechnical Evaluation Proposed Street Improvements 4403 South Dishman-Mica Road Spokane Valley, WA Dear Mr. Walker: As you authorized, we have completed a geotechnical evaluation for the proposed street improvements to the roadways adjacent to the above referenced site in Spokane Valley, Washington. The purpose of the evaluation is to provide earthwork recommendations and pavement design for the proposed improvements. This report summarizes the results of our site observations, engineering analyses and recommendations. PROJECT DESCRIPTION The project consists of street improvements to the roadways adjacent to the proposed Painted Hills residential development located at the above referenced address. The improvements consist of about 6,000 feet of roadway on South Dislunan Mica Road, East Thorpe Road, and South Madison Road. P.O. Box 1566, Veradale, WA 99037 Phone 509-209-6262 Geotechnical Evaluation Proposed Street Improvements Spokane Valley, WA Inland Pacific Engineering Company Project No. 16-249D 4403 S Dishman-Mica Rd June 26, 2017 Page 2 AVAILABLE INFORMATION We were provided a topographic survey for the project site by Whipple Consulting Engineers, Inc. (WCE). This topographic survey showed the existing roadways, existing structures, property lines, and existing ground surface elevation contours. This plan was prepared by WCE and was dated November 7, 2013. The site was used as a golf course prior to our evaluation. The site is relatively level with some elevated golf greens and excavated areas for water hazards. The site is primarily grass-covered with scattered trees along the fairways and pine trees in the undeveloped area to the northwest. The clubhouse building is present at the southwest corner. We were also provided civil plans for the roadway improvements. The plans showed the layout and elevations of the proposed roadways and elevation contours. The plans were prepared by WCE and dated August 17, 2016. In addition, we performed a preliminary geotechnical evaluation for the property in December 2013. The results of that evaluation, along with our opinions and recommendations, are summarized in our Preliminary Geotechnical Evaluation dated December 31, 2013. We also performed a geotechnical evaluation for certification of the existing levee along Chester Creek in April 2014. The results of that evaluation are summarized in our Geotechnical Evaluation report dated February 12, 2015. Furthermore, we performed a supplemental geotechnical evaluation in July 2015 consisting of ten, 50-foot borings in the south half of the property. The results of that evaluation are summarized in our Geotechnical Evaluation Phase 2 report dated July 23, 2015. We also performed a second supplemental geotechnical evaluation at the north end of the property to evaluate soil conditions at depth and to better define the static groundwater elevation in this area. We then performed a full-scale drywell test on a drywell installed near Boring B-1 from our second supplemental geotechnical evaluation. The results of these evaluations are summarized in our Supplemental Geotechnical Evaluation dated April 19, 2016 and our Full-Scale Drywell Testing report dated June 28, 2016. Lastly, we performed bore hole permeability testing at the north end of the property to evaluate infiltration rates at the depth of the drywell tested in our Full-Scale Drywell Testing report. We also tested infiltration rates at deeper depths. The results of that evaluation are summarized in our Bore Hole Permeability Testing report dated September 16, 2016. Geotechnical Evaluation Proposed Street Improvements Spokane Valley, WA Inland Pacific Engineering Company Project No. 16-249D 4403 S Dishman-Mica Rd June 26, 2017 Page 3 FIELD EVALUATION Procedures A geotechnical engineer from Inland Pacific Engineering Company (IPEC) observed the excavation of twelve test pits at the site. The test pits were excavated on February 23, 2017 using a backhoe operated by an independent firm under subcontract to IPEC. A geotechnical engineer from IPEC observed the test pit excavations and logged the surface and subsurface conditions. After we logged each test pit, the test pit was immediately backfilled. The soils encountered in the test pits were visually and manually classified in the field by our field personnel in accordance with ASTM D 2488, "Description and Identification of Soils (Visual- Manual Procedures)". The samples were returned to our facility for review of the classification by a geotechnical engineer and potential laboratory testing. Soils Encountered Geologic maps indicate the soils in this area consist primarily of alluvial and/or glacially deposited silts, clays, sands, and gravels. According to the Soil Survey of Spokane County, the site soils are classified by the Natural Resource Conservation Service (NRCS) as Narcisse silt loam (1080), Endoaquolls and Fluvaquents (1200), Hardesty ashy silt loam (1040), Phoebe ashy sandy loam (3130), Bong ashy loam, moist (3022), and Urban land-Springdale, disturbed complex (7170). The native soils encountered in the teste pits were consistent with the NRCS data. At the surface, the test pits encountered topsoil ranging from about 1/2 to 2 feet. The topsoil consisted of clayey to silty sand, silty gravel, and lean clay. Below the topsoil, the test pits along Dishman-Mica and Thorpe Road generally encountered alluvial soils to their termination depths. The alluvial soils consisted of lean clay and clayey to silty sand. Below the topsoil, the test pits along Madison Road generally encountered glacial outwash or alluvial soils to their termination depths. The glacial outwash consisted of clayey and silty to poorly graded sand with silt and silty gravel. The alluvial soils consisted of lean clay and clayey sand. Groundwater was encountered in Test Pits TP-4 through TP-7 at depths ranging from 2 to 4 feet below existing grades at the time of our exploration. Seasonal and annual fluctuations of groundwater levels should be anticipated. Laboratory Testing We obtained samples of the subgrade soil from Test Pit TP-2, TP-4, and TP-7 during our site investigation. Grain size analyses and modified Proctor tests were performed by us on the samples obtained from TP-4 and TP-7 in accordance with ASTM D6913 and ASTM D1557, respectively. The results of the tests are attached. Geotechnical Evaluation Proposed Street Improvements Spokane Valley, WA Inland Pacific Engineering Company Project No. 16-249D 4403 S Dishman-Mica Rd June 26, 2017 Page 4 In addition, resilient modulus (Mr) tests were performed on the samples obtained from TP-4 and TP-7 in accordance with AASHTO T307. The Mr tests were performed by Braun Intertec in Bloomington, Minnesota. Attached are data sheets summarizing the tests performed. ANALYSIS AND RECOMMENDATIONS S ub grade Preparation After removing the asphalt from the existing roadways, we anticipate the subgrade will consist of existing roadway embankment fill. We have assumed that during the construction of the existing roadways, the fill was compacted in accordance with local jurisdiction standards. Where road widening is planned, we recommend removing any existing topsoil. We recommend that the upper 8 inches of the resulting subgrade be scarified, moistened or dried to within 3 percent of optimum moisture, and compacted to a minimum of 95 percent of the modified Proctor maximum dry density determined in accordance with ASTM D 1557. Where fill is required, we recommend that it be similarly moisture conditioned and compacted. If there are areas that cannot be compacted, we recommend that the unstable soils be removed and replaced with soils similar to the surrounding subgrade soils. We recommend that the subgrade surface be shaped to provide for positive drainage to minimize the potential for water to pond in the subgrade. Because the site soils are low to highly frost- susceptible, it will be important to avoid creating "bathtubs" in the subgrade where water can pond and freeze, which could heave the pavement. If site grading and construction are anticipated during cold weather, recommend that good winter construction practices be observed. All snow and ice should be removed from excavated and fill areas prior to additional earthwork or construction. No fill or pavements should be placed on soil which have frozen or contain frozen material. Frozen soils should not be used as backfill or fill. Test Rolling Prior to placing the aggregate base, we recommend that all subgrade areas be proof-rolled with a loaded dump truck. This precautionary measure would assist in detecting any localized soft areas. Any soft areas discovered during the proof-rolling operation should be excavated and replaced with a suitable structural fill material. The structural fill should be similar to the existing subgrade soil type to provide a uniform subgrade. We recommend that the proof-rolling process be observed by an experienced geotechnical engineer to make the final evaluation of the subgrade. Geotechnical Evaluation Proposed Street Improvements Spokane Valley, WA Inland Pacific Engineering Company Project No. 16-249D 4403 S Dishman-Mica Rd June 26, 2017 Page 5 Pavement Section Design We performed a pavement section analysis in accordance with the "AASHTO Guide for Design of Pavement Structures, 1993" by the American Association of State Highway and Transportation Officials (AASHTO). For our analysis, we were provided an Average Daily Traffic (ADT) value of 5,300 for Dishman-Mica Road, 1,400 for Thorpe Road, and 1,700 for Madison Road. We were also provided percent trucks values of 2 percent for Thorpe and Madison Road, and 5 percent for Dishman-Mica Road. We were provided a percent growth value of 1.1 percent. Based on these provided parameters, we calculated the following Equivalent Single Axle Loads (ESAL): • Dishman-Mica Road: 2,617,545 • Thorpe Road: 330,000 • Madison Road: 389,954 We used resilient modulus values from the laboratory test results of (Mr) of 5,821 pounds per square inch (psi) for Thorpe Road and an Mr of 11,985 psi for Dishman-Mica and Madison Road. We also used the following parameters in our analysis provided in Chapter 8 of the City of Spokane Valley Street Standards, dated December of 2009: • • • • Reliability: Standard Deviation: Initial Serviceability Index: Terminal Serviceability Index: 90 percent 0.45 4.2 o Dishman-Mica Road: 2.50 o Thorpe Road: 2.25 o Madison Road: 2.25 • Structural Layer Coefficients: ■ Asphalt: 0.42 ■ Aggregate Base: 0.14 • Drainage Layer Coefficient: o Dishman-Mica Road: 1.05 o Thorpe Road: 0.85 o Madison Road: 0.95 Based on this data, we calculated the following design structural numbers: • Dishman-Mica Road: • Thorpe Road: • Madison Road: 3.4 3.1 2.5 Geotechnical Evaluation Proposed Street Improvements Spokane Valley, WA Inland Pacific Engineering Company Project No. 16-249D 4403 S Dishman-Mica Rd June 26, 2017 Page 6 Based on our analysis, we recommend the following pavement sections: • Dishman-Mica Road: o 4 inches of asphalt overlying • Thorpe Road: o 4 inches of asphalt overlying • Madison Road: o 4 inches of asphalt overlying 12 inches of crushed aggregate base 12 inches of crushed aggregate base 6 inches of crushed aggregate base We recommend specifying crushed aggregate base meeting the requirements of the Washington Department of Transportation (WSDOT) Standard Specification 9-03.9(3) for crushed gravel surfacing (base course and/or top course). We recommend that the asphalt concrete pavement meet the requirements of WSDOT Standard Specification for Class 'A inch HMA asphalt concrete pavements. We recommend that the crushed gravel surfacing be compacted to a minimum of 95 percent of the modified Proctor maximum dry density. We recommend that the asphaltic concrete surface be compacted to minimum of 92 percent of the Rice density. GENERAL RECOMMENDATIONS The analyses and recommendations submitted in this report are based on the data obtained from the test pits excavated at the locations indicated on the Test Pit Location Map on Figure 3. It should be recognized that the explorations performed for this evaluation reveal subsurface conditions only at discreet locations across the project site and that actual conditions in other areas could vary. Furthermore, the nature and extent of any such variations would not become evident until additional explorations are performed or until construction activities have begun. If significant variations are observed at that time, we may need to modify our conclusions and recommendations contained in this report to reflect the actual site conditions. We made water level observations in the test pits at the times and conditions stated on the test pit logs. These data were interpreted in the text of this report. The period of observation was relatively short and fluctuation in the groundwater level may occur due to rainfall, flooding, irrigation, spring thaw and other seasonal and annual factors not evident at the time the observations were made. Design drawings and specifications and construction planning should recognize the possibility of fluctuations. Geotechnical Evaluation Proposed Street Improvements Spokane Valley, WA Inland Pacific Engineering Company REMARKS Project No. 16-249D 4403 S Dishman-Mica Rd June 26, 2017 Page 7 This report is for the exclusive use of the addressee and the copied parties to use in design of the proposed project and to prepare construction documents. In the absence of our written approval, we make no representations and assume no responsibility to other parties regarding this report. The data, analyses, and recommendations may not be appropriate for other structures or purposes. We recommend that parties contemplating other structures or purposes contact us. Services performed by the geotechnical engineers for this project have been conducted in a manner consistent with that level of care ordinarily exercised by members of the profession currently practicing in this area under similar budget and time restraints. No warranty, expressed or implied, is intended or made. GENERAL REMARKS It has been a pleasure being of service to you for this project. If you have any questions or need additional information, please do not hesitate to call me at (509) 209-6262 at your convenience. Sincerely, Inland Pacific Engineering Company Gregory J. Voigt, P.E. Paul T. Nelson, P.E. Project Engineer Principal Engineer Attachments: Figure 1, Site Location Map Figure 2, NRCS Map Figure 3, Test Pit Location Maps Logs of Test Pits Descriptive Terminology Laboratory Test Results (*kV J. 4tz.. of v4A8694,`1,..v C./ •,:o 0 ...A \"CtGisTEO_c, A0NALsi FIGURE 1 ,•7•1!' Lr r ••••• • • ez o f . } 4 R I : Hate 4 :s s - ..i- e ; 0:r cu • • • 1 • • 4 ow, „ ,vo.t177. ,41 SITE ;J. 11 r Site Location Map IF'EC Project No. 16-249D June 26, 2017 Proposed Street Improvements 4403 S Dishman-Mica Rd Spokane Valley, WA Inland Pa dfic Engineering Company Geotrth:Eic al Er_ ..r, 2nd Comt*ing FIGURE 2 r • G • j.' %mow r. • ;.4 , si Jr L s • , „ .1231 71h .771 a eiiie0 if•it)01 — I 9% r1 'SITE E T horpe Rd • E4Oth Arr • , ! 3130 3064 • NRCS Map LPEC Project No. 16-249D June 26, 2017 Proposed Street Improvements 4403 S Dishman-Mica Rd Spokane Valley, WA bland Pacific Eopincesing Company GeotethMcalEngineesMgandConnailg FIGURE 3 _ 2 11, I 3 mir - • 011 L ,j,i -T Oagie s •ve* Test Pit Location Map 1 IPEC Project No. 16-249D June 26, 2017 Proposed Street Improvements 4403 S Dishman-Mica Rd Spokane Valley, WA Inland Pacific Engineeling Company Gentechnical Enejnetaing and Cansuking a_ cU U) H Luw cL H z z U) U z z z U) z < (.D ULLI z 0 U)H 00 U) U w 0 •Tr Cers4: CU 0 U H U GENERAL BH / TP IPEC Inland Pacific Engineering Company 3012 North Sullivan Road. Suite C Spokane Valley. WA 99216 Telephone: 509-209-6262 Fax: 509-290-5734 TEST PIT NUMBER TP-1 PAGE 1 OF 1 CLIENT NAI Black PROJECT NAME Proposed Street Improvements PROJECT NUMBER 16-249D PROJECT LOCATION Spokane Valley. WA DATE STARTED 2/23/17 COMPLETED 2/23/17 EXCAVATION CONTRACTOR Alpine Excavating EXCAVATION METHOD Backhoe LOGGED BY GV GROUND ELEVATION TEST PIT SIZE 30 inches GROUND WATER LEVELS: AT TIME OF EXCAVATION -- Not encountered CHECKED BY PTN AT END OF EXCAVATION — Not encountered NOTES AFTER EXCAVATION — Not encountered a. Cl j 0.0 CL < MATERIAL DESCRIPTION SC CL 2.5 0.5 (SC) CLAYEY SAND, fine-grained, trace roots, dark brown. moist. (Topsoil) (CL) LEAN CLAY with SAND, brown, moist. (Alluvium) 3.0 SC 5.0 5.0 (SC) CLAYEY SAND, fine-grained, brown, moist. (Alluvium) End of test pit. Groundwater not encountered. Test pit immediately backfilled. VEMENT DESIGN.GPJ 07 1L?.J z CP 0 z ."L1.1 07 GN \GINT A rz 07 - CC 07 O 07 O in cn 0.4 (-15 GINT STD US LAB.GD NERAL BH IPEC Inland Pacific Engineering Company 3012 North Sullivan Road, Suite C Spokane Valley, WA 99216 Telephone: 509-209-6262 Fax: 509-290-5734 TEST PIT NUMBER TP-2 PAGE 1 OF 1 CLIENT NAI Black PROJECT NAME Proposed Street Improvements PROJECT NUMBER 16-249D PROJECT LOCATION Spokane Valley. WA DATE STARTED 2/23/17 COMPLETED 2/23/17 EXCAVATION CONTRACTOR Alpine Excavating EXCAVATION METHOD Backhoe LOGGED BY GV GROUND ELEVATION TEST PIT SIZE 30 inches GROUND WATER LEVELS: AT TIME OF EXCAVATION -- Not encountered CHECKED BY PTN AT END OF EXCAVATION — Not encountered NOTES AFTER EXCAVATION — Not encountered U 02 uJ 0.0 111- 0 < CD MATERIAL DESCRIPTION GM CL 2.5 SC 5.0 ily .1_ A (GM) SILTY GRAVEL, fine to coarse-grained, trace roots, dark brown, moist. 0.5 \ (Topsoil) 3. 5.0 (CL) LEAN CLAY with SAND, brown, moist. (Alluvium) (SC) CLAYEY SAND. fine-grained, brown, moist. (Alluvium) End of test pit. Groundwater not encountered. Test pit immediately backfilled. CD U) Lu fp z Lu z z 0 U) F- Lu Lu a a, U) 0 a 3 a a LLi a a, fV c7, Co q a CD U) z cD a a LU Lu IPEC Inland Pacific Engineering Company 3012 North Sullivan Road, Suite C Spokane Valley, WA 99216 Telephone: 509-209-6262 Fax: 509-290-5734 TEST PIT NUMBER TP-3 PAGE 1 OF 1 CUENT NAI Black PROJECT NAME Proposed Street Improvements PROJECT NUMBER 16-249D PROJECT LOCATION Spokane Valley, WA DATE STARTED 2/23/17 COMPLETED 2/23/17 EXCAVATION CONTRACTOR Alpine Excavating EXCAVATION METHOD Backhoe GROUND ELEVATION TEST PIT SIZE 30 inches GROUND WATER LEVELS: AT TIME OF EXCAVATION — Not encountered LOGGED BY GV CHECKED BY PTN AT END OF EXCAVATION — Not encountered NOTES AFTER EXCAVATION — Not encountered ,_, D (1). 0.0 I a0 Ur < MATERIAL DESCRIPTION SM ' 2.5 SM 5.0 (SM) SILTY SAND, fine-grained, dark brown, moist. 0.5 \ (Topsoil) 5.0 (SM) SILTY SAND, fine-grained, brown, moist. (Alluvium) End of test pit. Groundwater not encountered. Test pit immediately backfilled. S PAVEMENT DESIGN. GPJ 9D PAINTED HI IPEC Inland Pacific Engineering Company 3012 North Sullivan Road. Suite C Spokane Valley. WA 99216 Telephone: 509-209-6262 Fax: 509-290-5734 TEST PIT NUMBER TP-4 PAGE 1 OF 1 CLIENT NAI Black PROJECT NAME Proposed Street Improvements PROJECT NUMBER 16-249D PROJECT LOCATION Spokane Valley, WA DATE STARTED 2/23/17 COMPLETED 2/23/17 EXCAVATION CONTRACTOR Alpine Excavating EXCAVATION METHOD Backhoe GROUND ELEVATION TEST PIT SIZE GROUND WATER LEVELS: 7_ AT TIME OF EXCAVATION 2.00 ft 30 inches LOGGED BY GV CHECKED BY PTN 1 AT END OF EXCAVATION 2.00 ft NOTES 2 AFTER EXCAVATION 2.00 ft 0— cr-- a 0.0 z 0 0 z _ 2.5 0 Co - 0 F-z o_ 0 0 C PROJECTS% 2 0 0 CD UJ z UJ 5.0 w o_ >-HW II, co —J 0_ a 2z c.o TESTS Fines = 38% Ci) a CL SM C7 2.0 V 5 MATERIAL DESCRIPTION (CL) LEAN CLAY with SAND, dark brown, moist. (Topsoil) (SM) SILTY SAND, fine-grained, with seams of Silt, brown, water-bearing. (Alluvium) End of test pit. Groundwater encountered at 2 feet. Test pit immediately backfilled. 6-249D PAINTED HILLS PAVEMENT DESIGN.GPJ IPEC Inland Pacific Engineering Company 3012 North Sullivan Road, Suite C Spokane Valley, WA 99216 Telephone: 509-209-6262 Fax: 509-290-5734 TEST PIT NUMBER TP-5 PAGE 1 OF 1 CLIENT NAI Black PROJECT NAME Proposed Street Improvements PROJECT NUMBER 16-249D PROJECT LOCATION Spokane Valley. WA DATE STARTED 2/23/17 COMPLETED EXCAVATION CONTRACTOR Alpine Excavating EXCAVATION METHOD Backhoe 2/23/17 GROUND ELEVATION TEST PIT SIZE 30 inches LOGGED BY GV CHECKED BY PTN NOTES GROUND WATER LEVELS: AT TIME OF EXCAVATION 2.00 ft AT END OF EXCAVATION 2.00 ft 2 AFTER EXCAVATION 2.00 ft 0_ LIJ 0 0.0 MATERIAL DESCRIPTION 5 0 0 2.5 F- L11 0 = a- U. J 1_IPEC PROJECTS1_2016 PROJ ti T STD US LAB.G 5.0 C :X ;/ N' , • CL 2.0 V 5. (CL) LEAN CLAY with SAND. trace roots, dark brown, moist. (Topsoil) (CL) LEAN CLAY with SAND, brown. wet. (Alluvium) End of test pit. Groundwater encountered at 2 feet. Test pit immediately backfilled. 0_ 0 U) 0 > ":( 0_ Un z 0_ .7o_ 45 0.0 0 0 z- 00 0 2.5 IPEC Inland Pacific Engineering Company 3012 North Sullivan Road, Suite C Spokane Valley, WA 99216 Telephone: 509-209-6262 Fax: 509-290-5734 TEST PIT NUMBER TP-6 PAGE 1 OF 1 CLIENT NAI Black PROJECT NAME Proposed Street Improvements PROJECT NUMBER 16-249D PROJECT LOCATION Spokane Valley. WA DATE STARTED 2/23/17 COMPLETED 2/23/17 EXCAVATION CONTRACTOR Alpine Excavating EXCAVATION METHOD Backhoe LOGGED BY GV CHECKED BY PTN NOTES GROUND ELEVATION GROUND WATER LEVELS: AT TIME OF EXCAVATION 3.50 ft TEST PIT SIZE 30 inches AT END OF EXCAVATION 3.50 ft AFTER EXCAVATION 3.50 ft - W 0 0_ 0 a_ C ,ROJECTS C US LAB.GOT - 6/21/17 12.49 - J I I H 0 0 5.0 W 0_ >- LJJ W CD D Z U (1). SC SC E g MATERIAL DESCRIPTION (SC) CLAYEY SAND, fine-grained, dark brown, moist. 0.5 \ (Topsoil) 1.5 (SC) CLAYEY SAND, fine-grained, brown, moist. (Alluvium) SP- SM 5.0 (SP-SM) POORLY GRADED SAND with SILT, fine to coarse-grained, brown, moist to water-bearing. (Glacial Outwash) End of test pit. Groundwater encountered at 3 1/2 feet. Test pit immediately backfilled. U) H LU o_ LU LU LL1 a_ 1_5 0 z LULU111 H z LL LU LU a_ Co 0 N O LU ry cd LULU H (/) (0 LULJJ LL1 (-7 IPEC Inland Pacific Engineering Company 3012 North Sullivan Road, Suite C Spokane Valley. WA 99216 Telephone: 509-209-6262 Fax: 509-290-5734 TEST PIT NUMBER TP-7 PAGE 1 OF 1 CLIENT NAI Black PROJECT NAME Proposed Street Improvements PROJECT NUMBER 16-249D PROJECT LOCATION Spokane Valley. WA DATE STARTED 2/23/17 COMPLETED 2/23/17 EXCAVATION CONTRACTOR Alpine Excavating EXCAVATION METHOD Backhoe GROUND ELEVATION TEST PIT SIZE GROUND WATER LEVELS: AT TIME OF EXCAVATION 4.00 ft 30 inches LOGGED BY GV CHECKED BY PTN 1 AT END OF EXCAVATION 4.00 ft NOTES 7 AFTER EXCAVATION 4.00 ft 0_ 0.0 TESTS E 0 o __, 0 MATERIAL DESCRIPTION 2.5 Fines = 50% 5.0 CL 2.0 (CL) LEAN CLAY with SAND, trace roots, dark brown. moist. (Topsoil) CL 5.0 (CL) SANDY LEAN CLAY, brown, moist to wet. (Alluvium) End of test pit. Groundwater encountered at 4 feet. Test pit immediately backfilled. LU as a LU 0-q LI) CO q 3 55 0 LI) _J q a fD "'Jr) a a (-5 a a a N [Id UJ a q (0 a CO UiUJ z UJ IPEC Inland Pacific Engineering Company 3012 North Sullivan Road, Suite C Spokane Valley, WA 99216 Telephone: 509-209-6262 Fax: 509-290-5734 TEST PIT NUMBER TP-8 PAGE 1 OF 1 CLIENT NAI Black PROJECT NAME Proposed Street Improvements PROJECT NUMBER 16-2490 PROJECT LOCATION Spokane Valley, WA DATE STARTED 2/23/17 COMPLETED 2/23/17 EXCAVATION CONTRACTOR Alpine Excavating EXCAVATION METHOD Backhoe LOGGED BY GV GROUND ELEVATION TEST PIT SIZE 30 inches GROUND WATER LEVELS: AT TIME OF EXCAVATION — Not encountered CHECKED BY PTN AT END OF EXCAVATION — Not encountered NOTES AFTER EXCAVATION — Not encountered = o v 0.0 MATERIAL DESCRIPTION SC • 1.0 (SC) CLAYEY SAND with GRAVEL, fine to medium-grained, dark brown, moist. (Topsoil) 2.5 SC 5.0 7 . , . 5.0 (SC) CLAYEY SAND with GRAVEL, fine to medium-grained, brown, moist. (Glacial Outwash) End of test pit. Groundwater not encountered. Test pit immediately backfilled. CD cD Cl z ) F- 2 LU ry CDUJ CO 0 CD O CD 0 z z — U L1J rf ,r7 o_ rr co 0 w 0 CD O CD O CD O co 0 rf, H :75 z CO 7/- z 111 IPEC Inland Pacific Engineering Company 3012 North Sullivan Road, Suite C Spokane Valley. WA 99216 Telephone: 509-209-6262 Fax: 509-290-5734 TEST PIT NUMBER TP-9 PAGE 1 OF 1 CLIENT NAI Black PROJECT NAME Proposed Street Improvements PROJECT NUMBER 16-249D PROJECT LOCATION Spokane Valley, WA DATE STARTED 2/23/17 COMPLETED 2/23/17 GROUND ELEVATION TEST PIT SIZE 30 inches EXCAVATION CONTRACTOR Alpine Excavating EXCAVATION METHOD Backhoe LOGGED BY GV CHECKED BY PTN NOTES GROUND WATER LEVELS: AT TIME OF EXCAVATION -- Not encountered AT END OF EXCAVATION — Not encountered AFTER EXCAVATION --- Not encountered 0- 0.0 >- Hw m 2z cr) cd. cn 0 12- 0 < MATERIAL DESCRIPTION SC e .0 1.0 (SC) CLAYEY SAND, fine-grained, dark brown, moist. (Topsoil) SM 2.0 (SM) SILTY SAND with GRAVEL, fine to medium-grained, brown, moist. (Glacial Outwash) 2.5 GM 5.0 (GM) SILTY GRAVEL, fine to coarse-grained, brown, moist. (Glacial Outwash) End of test pit. Groundwater not encountered. Test pit immediately backfilled. IPEC Inland Pacific Engineering Comp any Geotechnic al Engineering and Consulting RELATIVE DENSITY OR CONSISTENCY VERSUS SPT N-VALVE COARSE-GRAINED SOILS FINE-GRAINED SOILS DENSITY N(BLOWS/FT) CONSISTENCY N(BLOWS/FT) Very Loose 0 - 4 Very Soft 0 - 1 Loose 5 - 10 Soft -) _ 3 Medium-Dense 11 - 30 Rather Soft 4 - 5 Medium 6 - 8 Dense 31 - 50 Rather Stiff 9 - 12 Stiff 13 - 16 Very Dense > 50 Very Stiff 17 - 30 Hard > 30 USCS SOIL CLASSIFICATION MAJOR DIVISIONS GROUP DESCRIPTIONS Coarse- Grained Soils <50% passes #200 sieve Gravel and Gravelly Soils <50°° coarse fraction passes #4 sieve Gravel ,,,,,,,,,„ ,,„ GW Well Graded Gravel GP Poorly Graded Gravel Gravel ,,,,th. ,:,'.. rm.. GM Silty Gravel GC Clayey Gravel Sandy and Sandy Soils >5(1% coarse fraction passes #4 sieve Sand SW Well Graded Sand SP Poorly Graded Sand Sand ,,,•i: -: 2„ finc,: SM Silty Sand SC Clayey Sand Fine- Grained Soils >50% passes 4200 sieve Silt and Clay Liquid Limit < 50 ML CL OL Silt Lean Clay Organic Silt and Clay (low plasticity) Salt and Clay Liquid Limit > 50 MH CH OH Inorganic Silt Fat Clay Organic Clay and Silt lined to high plasticityl Highly Organic Soils PT Peat Muck MODIFIERS DESCRIPTION RANGE Occasional <5% Trace 5% - 12% With >12% MOISTURE CON1ENT DESCRIPTION FIELD OBSERVATION Dry Absence of moisture, dusty. dry to the touch Moist Dry of optimum moisture content Wet Wet of optimum moisture content MAJOR DIVISIONS WITH GRAIN SIZE SIEVE SIZE 12" 3" 3/4" 4 10 40 200 GRAIN SIZE (INCHES) 12 3 0.75 0.19 0.079 0.0171 0.0029 Boulders Cobbles Gravel Sand Silt and Clay Coarse Fine Coarse Medium Fine U) L1.1 0_ U z a q H t..1 0_ zz U) O 0_ ;6 H U 0 Fr5 ai 10 N 0 Inland Pacific Engineering Company GRAIN SIZE DISTRIBUTION IPEC 3012 North Sullivan Road. Suite C Spokane Valley, WA 99216 Telephone: 509-209-6262 Fax. 509-290-5734 CLIENT NAI Black PROJECT NAME Proposed Street Improvements PROJECT NUMBER 16-249D PROJECT LOCATION Spokane Valley. WA U.S. SIEVE OPENING IN INCHES 6 4 3 2 1.5 1 34 I 3 U.S. SIEVE NUMBERS I HYDROMETER 6 810 1416 210 30 40 50 60 10101410200 100 I 11 95 1\ 90 \ \ 0 85 )1080 75 \ 70 65 H (.) 60 >- 55 cci ix 50 z LT. I--45 z Li (..) \0 ce 40 ui o_ \•• 35 30 25 20 15 10 5 0 100 10 1 0 1 0.01 0.001 GRAIN SIZE IN MILLIMETERS GRAVEL SAND il COBBLES coarse fine coarse medium fine SILT OR CLAY BOREHOLE DEPTI- Classification LL PL I PI Cc Cu • TP-4 3.0 SILTY SAND(SM) X TP-7 3.0 SANDY LEAN CLAY(CL) BOREHOLE DEPTI- D100 D60 D30 D10 %Gravel %Sand %Silt %Clay • TP-4 3.0 12.7 0.245 3.4 58.8 37.8 X TP-7 3.0 9.5 0.268 0.2 49.7 50.1 Resilient Modulus Testing - AASHTO T307 US Customary Units Date: April 10, 2017 Client: Inland Pacific Engineering Company Paul Nelson P.O. Box 1566 Veradale, WA 99037 Sample Information Braun Sample ID./ File Name: 1 Sample Diameter, in.: 2.82 Sample M.C., % before, after: 13.9, 13.6 Sample Type: Type 2 Sample Height, in.: 5.58 Sample Dry Den., pcf: 97.8 Test Date: 06-Apr-2017 Desired M.C., %: 13.5 Failed in Shear?: YES Comments: Spokane Valley, WA Desired Dry Density., pcf: 98.8 Triaxial Shear Strength, psi: 44.2 Project: B1702069 Project Description: Resilient Modulus Test AASHTO T307 Client ID: Proposed Street Improvements Station: TP-4 COLUMN # PARAMETER DESIGNATION UNIT PRECISION SEQUENCE 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Chamber Confining Pressure Nominal Maximum Axial Stress Cycle No. Actual Applied Maximum Axial Load Actual Applied Cyclic Load Actual Applied Contact Load Actual Applied Maximum Axial Stress Actual Applied Cyclic Stress Actual Applied Contact Stress Recov Def. LVDT 1 Reading Recov Def. LVDT 2 Reading Average Recov Def LVDT 1 and LVDT 2 Resilient Strain Resilient Modulus S3 Scyclic cl Pmax Pcyclic Pcontact Smax Scyclic Scontact HI H2 H average Mr psi psi --- lbs. lbs. lbs. psi psi psi inches inches inches in/in psi 1 13.4 11.0 2.4 2.2 1.8 0.4 0.00074 0.00063 0.00069 0.00012 14,342 2 13.4 11.0 2.4 2.1 1.8 0.4 0.00071 0.00060 0.00066 0.00012 15,062 6.0 2.1 3 13.2 10.7 2.5 2.1 1.7 0.4 0.00078 0.00067 0.00072 0.00013 13,377 4 13.3 10.9 2.4 2.1 1.8 0.4 0.00085 0.00074 0.00079 0.00014 12,325 5 13.5 11.1 2.5 2.2 1.8 0.4 0.00082 0.00071 0.00077 0.00014 12,968 COLUMN AVERAGE 13.4 10.9 2.4 2.1 1.8 0.4 0.00078 0.00067 0.00073 0.00013 13,615 STANDARD DEV. 0.12 0.12 0.03 0.02 0.02 0.00 0.00006 0.00005 0.00006 0.00001 1,091 COLUMN # SEQUENCE 2 COLUMN # SEQUENCE 3 COLUMN 4 SEQUENCE 4 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1 25.2 21.3 3.9 4.1 3.4 0.6 0.00168 0.00149 0.00159 0.00028 12,106 2 25.2 21.3 3.9 4.0 3.4 0.6 0.00175 0.00156 0.00165 0.00030 11,586 6.0 4.0 3 25.2 21.4 3.8 4.0 3.4 0.6 0,00154 0.00136 0.00145 0.00026 13,326 4 25.2 21.6 3.6 4.1 3.5 0.6 0.00168 0.00149 0.00158 0.00028 12,307 5 25.1 21.2 3.8 4.0 3.4 0.6 0.00168 0.00149 0.00159 0.00028 12,060 COLUMN AVERAGE 25.2 21.4 3.8 4.0 3.4 0.6 0.00167 0.00148 0.00157 0.00028 12,277 STANDARD DEV. 0.07 0.14 0.12 0.01 0.02 0.02 0.00008 0.00007 0.00008 0.00001 643 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1 35.7 31.0 4.7 5.7 5.0 0.8 0.00257 0.00230 0.00244 0.00044 11,443 2 35.4 30.4 5.1 5.7 4.9 0.8 0.00267 0.00239 0.00253 0.00045 10,797 6.0 5.7 3 35.7 31.0 4.8 5.7 5.0 0.8 0.00257 0.00230 0.00243 0.00043 11,461 4 35.6 30.7 4.9 5.7 4.9 0.8 0.00267 0.00239 0.00253 0.00045 10,906 5 35.5 30.7 4.8 5.7 4.9 0.8 0.00278 0.00249 0.00264 0.00047 10,474 COLUMN AVERAGE 35.6 30.8 4.8 5.7 4.9 0.8 0.00260 0.00233 0.00246 0.00044 11,016 STANDARD DEV. 0.12 0.25 0.14 0.02 0.04 0.02 0.00006 0.00005 0.00006 0.00001 429 1 2 3 4 5 6 7 8 9 10 11 12 13 14 6.0 8.1 1 50.7 44.2 6.5 8.1 7.1 1.0 0.00385 0.00414 0.00400 0.00071 9,961 2 50.6 43.8 6.8 8.1 7.0 1.1 0.00383 0.00412 0.00397 0.00071 9,914 3 50.6 43.9 6.7 8.1 7.1 1.1 0.00384 0.00413 0.00398 0.00071 9,925 4 50.5 43.8 6.7 8.1 7.0 1.1 0.00365 0.00393 0.00379 0.00068 10,400 5 50.6 44.9 5.8 8.1 7.2 0.9 0.00384 0.00414 0.00399 0.00071 10,110 COLUMN AVERAGE 50.6 44.1 6.5 8.1 7.1 1.0 0.00380 0.00409 0.00395 0.00070 10,062 STANDARD DEV. 0.07 0.44 0.41 0.01 0.07 0.07 0.00008 0.00009 0.00009 0.00002 204 Sample ID: 1 Project: B1702069 Sheet No. 2 of 7 COLUMN # SEQUENCES COLUMN # SEQUENCE 6 COLUMN # SEQUENCE 7 1 2 3 4 5 6 7 8 9 I0 11 12 13 14 1 62.9 56.3 6.6 10.1 9.0 1.1 0.00483 0.00524 0.00503 0.00090 10,059 2 62.8 56.0 6.8 10.1 9.0 1.1 0.00481 0.00521 0.00501 0.00089 10,073 6.0 10.1 3 62.9 54.9 8.0 10.1 8.8 1.3 0.00482 0.00523 0.00502 0.00090 9,840 4 62.9 55.0 7.9 10.1 8.8 1.3 0.00462 0.00500 0.00481 0.00086 10,292 5 63.0 54.9 8.1 10.1 8.8 1.3 0.00481 0.00521 0.00501 0.00090 9,855 COLUMN AVERAGE 62.9 55.4 7.5 10.1 8.9 1.2 0.00478 0.00518 0.00498 0.00089 10,024 STANDARD DEV. 0.05 0.68 0.71 0.01 0.11 0.11 0.00009 0.00010 0.00010 0.00002 186 1 2 3 4 5 6 7 8 9 10 I 11 I 12 14 1 13.0 11.0 2.0 2.1 1.8 0.3 0.00057 0.00085 0,00071 0.00013 13,985 2 13.0 11.0 2.0 2.1 1.8 0.3 0.00059 0.00088 0.00073 0.00013 13,512 4.0 2.1 3 13.0 10.9 2.1 2.1 1.8 0.3 0.00062 0.00092 0.00077 0.00014 12,725 4 13.0 11.0 2.0 2.1 1.8 0.3 0.00063 0.00093 0.00078 0.00014 12,771 5 13.0 11.0 2.0 2.1 1.8 0.3 0.00058 0.00087 0.00073 0.00013 13,602 COLUMN AVERAGE 13.0 11.0 2.0 2.1 1.8 0.3 0.00060 0.00089 0.00074 0.00013 13,319 STANDARD DEV. 0.04 0.05 0.04 0.01 0.01 0.01 0.00003 0.00004 0.00003 0.00001 551 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1 24.8 21.3 3.5 4.0 3.4 0.6 0.00194 0.00206 0.00200 0.00036 9,597 2 24.8 21.7 3.1 4.0 3.5 0.5 0.00203 0.00215 0.00209 0.00037 9,312 4.0 4.0 3 24.7 21.4 3.3 4.0 3.4 0.5 0.00193 0.00205 0.00199 0.00036 9,649 4 25.0 21.7 3.3 4.0 3.5 0.5 0.00208 0.00220 0.00214 0.00038 9,128 5 24.8 21.4 3.4 4.0 3.4 0.6 0.00195 0.00207 0.00201 0.00036 9,541 COLUMN AVERAGE 24.8 21.5 3.3 4.0 3.5 0.5 0.00199 0.00211 0.00205 0.00037 9,445 STANDARD DEV. 0.09 0.18 0.14 0.02 0.03 0.02 0.00006 0.00007 0.00007 0.00001 219 Sample ID: 1 Project: B1702069 Sheet No. 3 of 7 COLUMN # SEQUENCE 8 1 2 3 4 5 6 7 8 9 10 11 12 13 14 36.6 32.1 4.5 5.9 5.2 0.7 0.00319 0.00338 0.00328 0.00059 8,804 2 36.6 32.2 4.4 5.9 5.2 0.7 0.00333 0.00353 0.00343 0.00061 8,450 4.0 5.9 3 36.6 32.0 4.6 5.9 5.1 0.7 0.00318 0.00337 0.00328 0.00059 8,788 4 36.7 32.1 4.6 5.9 5.2 0.7 0.00317 0.00336 0.00327 0.00058 8,845 5 36.6 32.0 4.6 5.9 5.1 0.7 0.00346 0.00367 0.00356 0.00064 8,085 COLUMN AVERAGE 36.6 32.1 4.5 5.9 5.2 0.7 0.00327 0.00346 0.00336 0.00060 8,595 • STANDARD DEV. , 0.03 0.08 0.09 0.00 0.01 0.01 0.00012 0.00013 0.00013 0.00002 326 COLUMN # 1 2 3 4 5 6 7 8 9 10 11 I 12 13 14 1 48.8 43.2 5.5 7.8 .6.9 0.9 0.00444 0.00469 0.00457 0.00082 8,523 2 48.6 42.9 5.7 7.8 6.9 0.9 0.00462 0.00488 0.00475 0.00085 8,120 SEQUENCE 9 4.0 7.8 3 48.6 42.1 6.5 7.8 6.8 1.1 0.00463 0.00489 0.00476 0.00085 7,969 4 48.7 43.8 4.9 7.8 7.0 0.8 0.00462 0.00489 0.00475 0.00085 8,295 5 48.8 42.8 5.9 7.8 6.9 1.0 0.00463 0.00489 0.00476 0.00085 8,095 COLUMN # SEQUENCE 10 COLUMN AVERAGE 48.7 43.0 5.7 7.8 6.9 0.9 0.00459 0.00485 0.00472 0.00084 8,200 STANDARD DEV. 0.09 0.63 0.59 0.01 0.10 0.10 0.00008 0.00009 0.00008 0.00002 214 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1 61.2 54.6 6.6 9.8 8.8 1.1 0.00562 0.00594 0.00578 0.00103 8,496 2 61.3 54.0 7.2 9.8 8.7 1.2 0.00566 0.00598 0.00582 0.00104 8,358 4.0 9.8 3 61.2 53.2 8.0 9.8 8.6 1.3 0.00565 0.00596 0.00580 0.00104 8,256 4 61.2 54.4 6.8 9.8 8.7 1.1 0.00561 0.00591 0.00576 0.00103 8,497 5 61.2 53.8 7.4 9.8 8.6 1.2 0.00539 0.00568 0.00554 0.00099 8,735 COLUMN AVERAGE 61.2 54.0 7.2 9.8 8.7 1.2 0.00558 0.00589 0.00574 0.00103 8,468 STANDARD DEV. 0.04 0.53 0.53 0.01 0.09 0.09 0.00011 0.00012 0.00012 0.00002 180 Sample ID: 1 Project: B1702069 Sheet No. 4 of 7 COLUMN # SEQUENCE 11 COLUMN # SEQUENCE 12 COLUMN 4 SEQUENCE 13 1 2 3 4 5 6 7 8 9 10 II 12 13 14 2.0 1.8 2 3 4 5 9.5 1.6 1.8 1.5 0.3 0.00041 0.00083 0.00062 0.00011 13,686 9.5 1.6 1.8 1,5 0.3 0.00051 0.00095 0.00073 0.00013 11,774 9.4 1.7 1.8 1.5 0.3 0.00045 0.00089 0.00067 0.00012 12,675 9.5 1.6 1.8 1.5 0.3 0.00040 0.00083 0.00062 0.00011 13,915 11.0 9.4 1.7 1.8 1.5 0.3 0.00049 0.00095 0.00072 0.00013 11,666 COLUMN AVERAGE 11.1 9.5 1.6 1.8 1.5 0.3 0.00045 0.00089 0.00067 0.00012 12,743 STANDARD DEV 0.03 0.08 0.05 0.01 0.01 0.01 0.00005 0.00006 0.00005 0.00001 1,045 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1 23.1 20.2 2.9 3.7 3.2 0.5 0.00234 0.00258 0.00246 0.00044 7,387 2 23.0 20.2 2.8 3.7 3.2 0.5 0.00245 0.00268 0.00257 0.00046 7,088 2.0 3.7 3 23.0 20.2 2.8 3.7 3.3 0.4 0.00244 0.00268 0.00256 0.00046 7,118 4 23.0 20.2 2.9 3.7 3.2 0.5 0.00233 0.00256 0.00245 0.00044 7,413 5 23.1 20.3 2.8 3.7 3.3 0.5 0.00234 0.00258 0.00246 0.00044 7,423 COLUMN AVERAGE 23.0 20.2 2.8 3.7 3.2 0.5 0.00238 0.00262 0.00250 0.00045 7,286 STANDARD DEV. 0.04 0.05 0.04 0.01 0.01 0.01 0.00006 0.00006 0.00006 0.00001 168 1 2 3 4 5 6 7 8 9 10 11 12 13 14 2.0 5.3 1 33.2 29.2 4.0 5.3 4.7 0.7 0.00393 0.00411 0.00402 0.00072 6,526 2 33.2 28.9 4.3 5.3 4.6 0.7 0.00410 0.00429 0.00419 0.00075 6,200 3 33.2 29.3 3.9 5.3 4.7 0.6 0.00409 0.00428 0.00419 0.00075 6,308 4 33.2 28.7 4.4 5.3 4.6 0.7 0.00392 0.00411 0.00402 0.00072 6,441 5 33.2 29.1 4.1 5.3 4.7 0.7 0.00391 0.00410 0.00401 0.00072 6,538 COLUMN AVERAGE 33.2 29.0 4.1 5.3 4.7 0.7 0.00399 0.00418 0.00408 0.00073 6,402 STANDARD DEV. 0.04 0.23 0.23 0.01 0.04 0.04 0.00009 0.00010 0.00009 0.00002 146 Sample ID: 1 Project: B1702069 Sheet No. 5 of 7 COLUMN I) SEW lENCE 14 COLUMN SEQI1ENCE 15 1 :_. 2 3 4 5 6 7 8 9 10 I I 12 13 14 I 44 7 36 2 8.5 7 2 5 8 1 4 0 00547 0 00573 0 00560 0 o0100 5,821 2 44 6 16 8 7.8 7 2 5 9 1 3 0.00549 0 00575 0.00562 0.00100 5,886 2 0 7 2 3 44 6 36 5 8.1 7 2 5 9 1 3 0 00523 0 00548 0 00536 0 00096 6.134 4 44 6 37 .3 7 3 7 2 6 0 1 2 0 00549 0 00575 0 00562 0 00100 5,978 5 44 7 36 3 8.4 7 2 5 8 1 3 0 00548 0.00573 0.00560 0 00100 5,830 COLUMN AVERAGE 44 7 36 6 8.0 7 2 5.9 1 3 0 00543 0 00569 0.00556 0 00099 5,930 STANDARD DEN 0 04 0.44 0 46 0 01 0 07 0 07 0 00011 0.00012 0 0001 1 0.00002 130 1 2 , 4 5 6 7 8 9 10 I I 12 13 14 1 56 7 47 0 9.6 9 1 7 6 1 5 0 00669 0 00695 0.00682 0 00122 6.202 2 56 7 48 2 8.6 9 I 7 7 14 0 00704 0 00729 0.00716 0 00128 6,050 2 0 q I 3 56 7 48 0 8.7 9 1 7 7 14 0 00704 0 00729 0 00716 0 00128 0,024 4 56 7 47 9 8.9 9 1 7 7 1 4 0 00672 0.00696 0.00684 0 00122 6,298 5 56 7 46 8 9.9 9 1 7 5 1.6 0 00674 0.00698 0.00686 0 00123 6,136 COLUMN AVERAGE 56 7 47 6 9.1 9 I 7 6 1 5 0 00685 0.00709 0 00697 0 00124 6.142 STANDARD DEV 0 03 0 60 0 59 0 01 0 10 0 10 0 00017 0.00018 0.00018 0 00003 112 Sample II) 1 Protect 131702069 Sheet No 6 017 Erik J. Knudson I.aboratory Technician Quick Shear Confining Pressure 4 PSI Peak Shear Stress (psi) = 44.2 50.00 45.00 40.00 35.00 30.00 ,—, :6 25' 00 r II Un CW ;.• -1••• to 20.00 15.00 10 00 5.00 000 0 2 3 4 5 6 % Strain Sample ID. I Project: B1702069 Sheet No. 7 of 7 Universal Model Calculations - US Customary Units Braun Sample ID: 1 Station: TP-4 Seq. Conf. psi Axial Stress psi Bulk psi Deviator psi Mr psi Pred. Mr psi Ln(Mr) Ln(Bulk) Ln(Dev) 1 6.0 2.1 20.1 1.8 13,615 16,232 9.519 3.003 0.563 2 6.0 4.0 22.0 3.4 12,277 12,263 9.415 3.093 L233 3 6.0 5.7 23.7 4.9 11,016 10,688 9.307 3.166 1.598 4 6.0 8.1 26.1 7.1 10,062 9,465 9.217 3.263 1.959 5 6.0 10.1 28.1 8.9 10,024 8,828 9.213 3.336 2.187 6 4.0 2.1 14.1 1.8 13,319 13,025 9.497 2.645 0.569 7 4.0 4.0 16.0 3.5 9,445 10,061 9.153 2.772 1.239 8 4.0 5.9 17.9 5.2 8,595 8,818 9.059 2.884 1.640 9 4.0 7.8 19.8 6.9 8,200 8,112 9.012 2.987 1.932 10 4.0 9.8 21.8 8.7 8,468 7,672 9.044 3.084 2.161 11 2.0 1.8 7.8 1.5 12,743 9,796 9.453 2.052 0.418 12 2.0 3.7 9.7 3.2 7,286 7,662 8.894 2.272 1.178 13 2.0 5.3 11.3 4.7 6,402 7,026 8.764 2.428 1.540 14 2.0 7.2 13.2 5.9 5,930 6,853 8.688 2.578 1.773 15 2.0 9.1 15.1 7.6 6,142 6,534 8.723 2.714 2.034 Project: B1702069 Universal Model Calculations - US Customary Units Braun Sample ID: 1 Station: TP-4 SUMMARY OUTPUT Regression Statistics Multiple R R Square Adjusted R Square Standard Error Observations 0.918187299 0.843067917 0.816912569 0.11966659 15 ANOVA ax5 Value t-Stat kl k2 k3 3475.7918 0.606811974 -0.499551386 32.43723 5.954231958 -7.74275784 R-sqr Adj. 0.8169126 Std Err 0.1196666 or 12.71% Regression Residual Total df 2 12 14 SS MS 0.923161964 0.461581 0.171841114 0.0143201 1.095003078 F Significance F 32.2331 1.49372E-05 Project: B1702069 Coefficients Standard Error t Stat 8.153577586 0.606811974 -0.49955139 P-value Lower 95% Upper 95% Lower 95.0% Upper 95.0% Intercept X Variable 1 X Variable 2 0.251364796 32.43723 4.661E-13 0.10191272 5.954232 6.67E-05 0.064518534 -7.742758 5.246E-06 7.605900745 0.384763232 -0.640125196 8.701254427 0.828860715 -0.358977576 7.605900745 8.701254427 0.384763232 0.828860715 -0.640125196 -0.358977576 Universal Model Graph - US Customary Units Braun Sample ID: 1 Station: TP-4 Project: B1702069 18,000 16,000 14,000 12,000 '1: 10,000 z 8,000 6,000 4,000 2,000 0 1 0 0 • —1-- —IF- —1r- 0 0 A a 0 0 II A A • 0 A 0 1 2 3 4 5 6 Deviator Stress, psi 7 8 9 10 6 psi 4 psi 2 psi Predicted 6 psi Predicted 4 psi Predicted 2 psi z 0 UiLIJ H 0 o_ 0 z a z UiLIJ 0 LIJ a a, C O LLI LUO H H 0 c d (0 (7, 0 a C- IPEC Inland 3012 Spokane Telephone: Fax: Pacific North V a lley. 509-290-5734 Engineering Sullivan Road. WA 9921 509-209-62626 Company Suite C PROJECT PROJECT MOISTURE NAME LOCATION Proposed -DENSITY RELATIONSHIP Street Improvements CLIENT PROJECT NAI Black NUMBER 16-249D Spokane Valley, WA DRY DENSITY, pcf —4 CO CO (0 CD 0 0 ._, _.> I \J IV C.A.) OJ cri © cri cp CT! 0 cri c. (11 0 Crl 0 cr .---, Sample Description Test Method ID of Material Maximum Optimum TEST Dry Water ATTERBERG LL TP-4 \ \ SILTY SAND(SM) ASTM D1557 Method A RESULTS Density Specific Content of 100% LIMITS PL 104.0 PCF % PI 13.5 Equal 2.80 2.70 2.60 '', \ \ Curves for Gravity Saturation to: 1 -I 1 , ■I 5 10 15 20 WATER CONTENT. 25 30 % 35 40 45 Resilient Modulus Testing - AASHTO T307 US Customary Units Date: April 10, 2017 Client: Inland Pacific Engineering Company Paul Nelson P.O. Box 1566 Veradale, WA 99037 Sample Information Braun Sample ID./ File Name: 1 Sample Diameter, in.: 2.80 Sample M.C., % before, after: 14.7, 14.2 Sample Type: Type 2 Sample Height, in.: 5.51 Sample Thy Den., pcf: 106.1 Test Date: 06-Apr-2017 Desired ME., %: 14.3 Failed in Shear?: YES Comments: Spokane Valley, WA Desired Dry Density., pcf: 104.7 Triaxial Shear Strength, psi: 45.3 Project: B1702069 Project Description: Resilient Modulus Test AASHTO T307 Client ID: Proposed Street Improvements Station: TP-7 COLUMN 4 PARAMETER DESIGNATION UNIT PRECISION SEQUENCE 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Chamber Confining Pressure Nominal Maximum Axial Stress Cycle No. Actual Applied Maximum Axial Load Actual Applied Cyclic Load Actual Applied Contact Load Actual Applied Maximum Axial Stress Actual Applied Cyclic Stress Actual Applied Contact Stress Recov Def LVDT 1 Reading Recov Def. LVDT 2 Reading Average Recov Def LVDT 1 and LVDT 2 Resilient Strain Resilient Modulus S3 Scyclic cl Pmax Pcyclic Pcontact Smax Scyclic Scontact HI H2 H average Mr psi psi --- lbs. lbs. lbs. psi psi psi inches inches inches in/in psi 1 14.2 11.8 2.4 2.3 1.9 0.4 0.00049 0.00052 0.00051 0.00009 21,081 2 14.3 11.9 2.3 2.3 1.9 0.4 0.00052 0.00057 0.00054 0.00010 19,724 6.0 2.3 3 14.2 11.8 2.4 2.3 1.9 0.4 0.00051 0.00056 0.00053 0.00010 19,921 4 14.2 11.8 2.4 2.3 1.9 0.4 0.00047 0.00051 0.00049 0.00009 21,508 5 14.2 11.8 2.5 2.3 1.9 0.4 0.00050 0.00055 0.00053 0.00010 20,044 COLUMN AVERAGE 14.2 11.8 2.4 2.3 1.9 0.4 0.00050 0.00054 0.00052 0.00009 20,456 STANDARD DEV. 0.02 0.07 0.05 0.00 0.01 0.01 0.00002 0.00002 0.00002 0.00000 789 COLUMN # SEQUENCE 2 COLUMN # SEQUENCE 3 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1 26.5 22.8 33 4.3 3.7 0.6 0.00104 0.00112 0.00108 0.00020 18,948 2 26.5 22.9 3.6 4.3 3.7 0.6 0.00100 0.00107 0.00103 0.00019 19,938 6.0 4.3 3 26.5 22.8 3.7 4.3 3.7 0,6 0.00099 0.00107 0.00103 0.00019 19,878 4 26.4 22.8 3.6 4.3 3.7 0.6 0.00099 0.00107 0.00103 0.00019 19,906 5 26.3 22.7 3.6 4.3 3.7 0.6 0.00095 0.00102 0.00099 0.00018 20,678 COLUMN AVERAGE 26.4 22.8 3.6 4.3 3.7 0.6 0.00099 0.00107 0.00103 0.00019 19,870 STANDARD DEV. 0.07 0.06 0.07 0.01 0.01 0.01 0.00003 0.00004 0.00003 0.00001 614 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1 38.3 33.5 4.8 6.2 5.4 0.8 0.00165 0.00180 0.00173 0.00031 17,453 2 38.3 33.4 4.9 6.2 5.4 0.8 0.00150 0.00164 0.00157 0.00028 19,131 6.0 6.2 3 38.3 33.5 4.8 6.2 5.4 0.8 0.00157 0.00172 0.00164 0.00030 18,362 4 38.4 33.6 4.8 6.2 5.4 0.8 0.00157 0.00172 0.00165 0.00030 18,344 5 38.5 33.6 4.9 6.2 5.4 0.8 0.00156 0.00171 0.00164 0.00030 18,434 COLUMN AVERAGE 38.4 33.5 4.8 6.2 5.4 0.8 0.00157 0.00172 0.00165 0.00030 18,345 STANDARD DEV. _ 0.08 0.08 0.04 0.01 0.01 0.01 0.00007 0.00008 0.00008 0.00001 596 1 2 3 4 5 I 6 7 8 I 9 10 I 11 12 13 14 1 51.1 45.2 5.9 8.3 7.3 1.0 0.00218 0.00237 0.00227 0.00041 17,902 2 51.2 45.2 6.0 8.3 7.3 1.0 0.00217 0.00237 0.00227 0.00041 17,907 6.0 8.3 3 51.1 45.2 6.0 8.3 7.3 1.0 0.00227 0.00247 0.00237 0.00043 17,140 4 51.2 45.3 5.8 8.3 7.3 0.9 0.00216 0.00235 0.00226 0.00041 18,047 5 51.1 45.2 5.9 8.3 7.3 1.0 0.00226 0.00246 0.00236 0.00043 17,232 COLUMN AVERAGE 51.2 45.2 5.9 8.3 7.3 1.0 0.00221 0.00240 0.00231 0.00042 17,645 STANDARD DEV. 0.04 0.06 0.07 0.01 0.01 0.01 0.00005 0.00006 0.00005 0.00001 425 COLUMN 4 SEQUENCE 4 Sample ID: 1 Project: B1702069 Sheet No. 2 of 7 COLUMN # SEQUENCE 5 COLUMN # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1 63.5 55.7 7.8 10.3 9.0 1.3 0.00279 0.00305 0.00292 0.00053 17,171 2 63.5 56.3 7.2 10.3 9.1 1.2 0.00291 0.00319 0.00305 0.00055 16,615 6.0 10.3 3 63.3 56.4 6.9 10.3 9.1 1.1 0.00278 0.00304 0.00291 0.00053 17,403 4 63.6 56.5 7.1 10.3 9.1 1.2 0.00292 0.00319 0.00306 0.00055 16,605 5 63.4 55.7 7.7 10.3 9.0 1.3 0.00295 0.00322 0.00308 0.00056 16,264 COLUMN AVERAGE 63.5 56.1 7.3 10.3 9.1 1.2 0.00287 0.00314 0.00300 0.00054 16,812 STANDARD DEV. 0.10 0.37 0.39 0.02 0.06 0.06 0.00008 0.00008 0.00008 0.00001 464 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1 13.2 11.2 1.9 2.1 1.8 0.3 0.00046 0.00056 0.00051 0.00009 19,788 2 13.2 11.2 2.0 2.1 1.8 0.3 0.00042 0.00052 0.00047 0.00009 21,408 4.0 2.1 3 13.2 11.2 2.0 2.1 1.8 0.3 0.00040 0.00051 0.00046 0.00008 22,194 4 13.2 11.3 1.9 2.1 1.8 0.3 0.00042 0.00052 0.00047 0.00009 21,464 5 13.2 11.2 2.0 2.1 1.8 0.3 0.00046 0.00057 0.00051 0.00009 19,655 COLUMN AVERAGE 13.2 11,2 2.0 2.1 1.8 0.3 0.00043 0.00054 0.00048 0.00009 20,902 STANDARD DEV. 0.02 0.04 0.04 0.00 0.01 0.01 0.00002 0.00003 0.00003 0.00000 1,122 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1 25.6 22.3 3.4 4.2 3.6 0.5 0.00109 0.00117 0.00113 0.00020 17,677 2 25.6 22.2 3.4 4.1 3.6 0.6 0.00108 0.00116 0.00112 0.00020 17,900 4.0 4.1 3 25.6 22.5 3.1 4.2 3.6 0.5 0.00108 0.00116 0.00112 0.00020 18,068 4 25.5 22.2 3.3 4.1 3.6 0.5 0.00107 0.00115 0.00111 0.00020 18,003 5 25.6 22.5 3.1 4.1 3.6 0.5 0.00113 0.00121 0.00117 0.00021 17,291 COLUMN AVERAGE 25.6 22.3 3.3 4.1 3.6 0.5 0.00109 0.00117 0.00113 0.00020 17,788 STANDARD DEV. 0.04 0.16 0.15 0.01 0.03 0.03 0.00002 0.00002 0.00002 0.00000 315 SEQUENCE 6 COLUMN # SEQUENCE 7 Sample ID: 1 Project: B1702069 Sheet No. 3 of 7 COLUMN # SEQUENCE 8 COLUMN # SEQUENCE 9 COLUMN # SEQUENCE 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1 37.7 33.4 4.3 6.1 5.4 0.7 0.00184 0.00196 0.00190 0.00034 15,850 2 37.8 33.5 4.3 6.1 5.4 0.7 0.00174 0.00186 0.00180 0.00033 16,722 4.0 6.1 3 37.7 33.6 4.1 6.1 5.4 0.7 0.00184 0.00196 0.00190 0.00034 15,865 4 37.8 33.2 4.6 6.1 5.4 0.7 0.00167 0.00178 0.00173 0.00031 17,283 5 37.8 33.8 4.1 6.1 5.5 0.7 0.00168 0.00179 0.00174 0.00031 17,479 COLUMN AVERAGE 37.8 33.5 4.3 6.1 5.4 0.7 0_00175 0.00187 0.00181 0.00033 16,640 STANDARD DEV. 0.05 0.22 0.20 0.01 0.04 0.03 0.00008 0.00009 0.00008 0.00002 766 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1 49.8 44.2 5.6 8.1 7.2 0.9 0.00247 0.00261 0.00254 0.00046 15,656 2 49.9 44.3 5.6 8.1 7.2 0.9 0.00249 0.00263 0.00256 0.00046 15,588 4.0 8.1 3 50.0 44.3 5.7 8.1 7.2 0.9 0.00247 0.00261 0.00254 0.00046 15,672 4 49.9 43.9 6.0 8.1 7.1 1.0 0.00249 0.00263 0.00256 0.00046 15,404 5 49.9 44.2 5.7 8.1 7.2 0.9 0.00248 0.00262 0.00255 0.00046 15,577 COLUMN AVERAGE 49.9 44.2 5.7 8.1 7.2 0.9 0.00248 0.00262 0.00255 0.00046 15,579 STANDARD DEV. 0.09 0.17 0.17 0.01 0.03 0.03 0.00001 0.00001 0.00001 0.00000 107 2 3 4 5 6 7 8 9 10 11 12 13 14 1 61.1 54.6 6.5 9.9 8.8 1.0 0.00320 0.00340 0.00330 0.00060 14,869 2 60.6 53.2 7.4 9.8 8.6 1.2 0.00298 0.00317 0.00308 0.00055 15,573 4.0 10.0 3 62.2 55.2 7.0 10.1 8.9 1.1 0.00317 0.00338 0.00328 0.00059 15,159 4 62.0 54.7 7.3 10.0 8.9 1.2 0.00301 0.00321 0.00311 0.00056 15,843 5 62.1 54.8 7.4 10.1 8.9 1.2 0.00331 0.00352 0.00342 0.00062 14,431 COLUMN AVERAGE 61.6 54.5 7.1 10.0 8.8 1.1 0.00314 0.00334 0.00324 0.00058 15,175 STANDARD DEV. 0.72 0.74 0.38 0.12 0.12 0.06 0.00014 0.00014 0.00014 0.00003 560 Sample ID: 1 Project: B1702069 Sheet No. 4 of 7 COLUMN # SEQUENCE 11 COLUMN # SEQUENCE 12 COLUMN # SEQUENCE 13 1 2 3 4 5 6 7 8 9 10 L 11 12 13 14 1.9 1.9 I 2 3 4 5 12.0 10.4 1.6 2.0 1.7 0.3 0.00028 0.00059 0.00043 0.00008 21,647 12.0 10.4 1.6 1.9 1.7 0.3 0.00032 0.00063 0.00047 0.00009 19,828 12.0 10.3 1.7 1.9 1.7 0.3 0.00028 0.00060 0.00044 0.00008 21,125 12.0 10.3 1.7 1.9 1.7 0.3 0.00025 0.00055 0.00040 0.00007 23,217 12.0 10.4 1.6 2.0 1.7 0.3 0.00028 0.00059 0.00044 0.00008 21,354 COLUMN AVERAGE 12.0 10.4 1.7 1.9 1.7 0.3 0.00028 0.00059 0.00044 0.00008 21,434 STANDARD DEV. 0.02 0.06 0.05 0.00 0.01 0.01 0.00002 0.00003 0.00002 0.00000 1,215 1 2 3 4 5 6 L 7 8 9 10 11 12 13 14 1 24.1 21.3 2.8 3.9 3.4 0.5 0.00130 0.00137 0.00134 0.00024 14,305 2 24.0 21.3 2.7 3.9 3.5 0.4 0.00130 0.00137 0.00134 0.00024 14,336 2.0 3.9 3 24.1 21.2 2.9 3.9 3.4 0.5 0.00131 0.00138 0.00134 0.00024 14,185 4 24.1 21.2 2.9 3.9 3.4 0.5 0.00131 0.00138 0.00134 0.00024 14,196 5 24.0 21.2 2.8 3.9 3.4 0.4 0.00119 0.00126 0.00123 0.00022 15,568 COLUMN AVERAGE 24.1 21.2 2.8 3.9 3.4 0.5 0.00128 0.00135 0.00132 0.00024 14,518 STANDARD DEV. 0.04 0.06 0.07 0.01 0.01 0.01 0.00005 0.00005 0.00005 0.00001 591 1 2 3 4 5 6 7 8 9 10 I 11 12 13 14 1 35.9 32.2 3.8 5.8 5.2 0.6 0.00212 0.00223 0.00217 0.00039 13,293 2 35.9 31.9 4.0 5.8 5.2 0.7 0.00204 0.00214 0.00218 0.00038 13,745 2.0 5.8 3 35.9 32.3 3.6 5.8 5.2 0.6 0.00213 0.00224 0.00218 0.00039 13,317 4 36.0 32.3 3.7 5.8 5.2 0.6 0.00213 0.00224 0.00218 0.00039 13,323 5 35.9 32.0 3.9 5.8 5.2 0.6 0.00203 0.00214 0.00209 0.00038 13,800 COLUMN AVERAGE 35.9 32.1 3.8 5.8 5.2 0.6 0.00209 0.00220 0.00216 0.00039 13,496 STANDARD DEV. 0.04 0.18 0.16 0.01 0.03 0.03 0.00005 0.00005 0.00004 0.00001 254 Sample ID: 1 Project: B1702069 Sheet No. 5 of 7 1) C014 IMN 50Q1IENCE 14 COLA WIN if SEQUENCE: 15 I 2 3 4 5 6 7 8 9 10 11 12 13 14 2 0 7 8 1 2 3 4 5 48 1 40 2 - 8 7 8 6 5 1 3 0 00287 0 00301 0 00294 0 00053 12,301 48 0 41 5 6 5 7 8 6.7 1 1 0.00287 0.00300 0 00293 0.00053 12,736 48 I 41 4 6 7 7 8 6 7 1 1 0 00300 0 00314 (I 00307 0 00055 12,111 48 0 39 9 8.1 7 8 6 5 1.3 0 00286 0 00299 0 00293 0 00053 12,280 48 I 41 3 6.8 7 8 6.7 I I 0 00300 0 00314 0300307 0 00055 12,089 C01.1 WIN AVERAGE 48 0 40 9 7.2 7.8 6 6 1 2 0 00292 0 00305 0 00299 0310054 12,307 STANDARD DIN 0 03 0 72 0 72 0 01 0 12 0 12 0 00007 0 00008 0 00007 0 00001 257 1 2 - 3 4 5 6 7 8 9 10 I I 12 13 14 1 60 3 50 9 9 4 9 8 8 2 1 5 0 00352 0 00369 0 00361 0 00065 12,699 2 60 2 51 I 9 2 9 8 8 3 1 5 0 00351 0 00367 0.00359 0.00065 12,792 2 0 0 8 3 60 3 51 0 5 4 9 8 8 4 1 4 0 00352 0 00369 0 00361 0 00065 12.940 4 60 2 52 4 7.8 9 8 S 5 3 0 00384 0 00402 (100393 0 00071 11.985 5 60 3 52 I 8.2 9 8 8 5 1 .3 0 00369 0 00387 0 00378 0 00068 12,409 COLUMN AVERAGE 60.2 51 7 8.6 9.8 8 4 14 0 00362 0 00379 0 00370 0 00067 12,565 STANDARD DEN 0 04 0 67 0 67 0 01 0 1 1 0 11 0 00014 0.00015 0 00015 0 00003 378 Sample II) I riThect 181702060 Sheet No 6 47 br ( J. Knudson Laboratory Technician Quick Shear Confining Pressure 4 PSI Peak Shear Stress (psi) = 45.3 50.00 45.00 6 Fil•—• -------...„.........„,......... 40.00 35 00 30.00 25.00 tu s. (7) 20.00 15.00 -- 10.00 5.00 0.00 0 2 3 4 5 °A) Strain Sample ID: 1 Project: B1702069 Sheet No. 7 of 7 Universal Model Calculations - US Customary Units Braun Sample ID: 1 Project: B1702069 Station: TP-7 Seq. Conf. psi Axial Stress psi Bulk psi Deviator psi Mr psi Pred. Mr psi Ln(Mr) Ln(Bulk) Ln(Dev) 1 6.0 2.3 20.3 1.9 20,456 23,592 9.926 3.011 0.650 2 6.0 4.3 22.3 3.7 19,870 19,613 9.897 3.104 1.307 3 6.0 6.2 24.2 5.4 18,345 17,768 9.817 3.187 1.692 4 6.0 8.3 26.3 7.3 17,645 16,552 9.778 3.269 1.992 5 6.0 10.3 28.3 9.1 16,812 15,799 9.730 3.342 2.208 6 4.0 2.1 14.1 1.8 20,902 21,278 9.948 2.649 0.598 7 4.0 4.1 16.1 3.6 17,788 17,740 9.786 2.782 1.287 8 4.0 6.1 18.1 5.4 16,640 16,138 9.720 2.897 1.692 9 4.0 8.1 20.1 7.2 15,579 15,250 9.654 3.000 1.969 10 4.0 10.0 22.0 8.8 15,175 14,667 9.627 3.090 2.178 11 1.9 1.9 7.7 1.7 21,434 17,875 9.973 2.047 0.519 12 2.0 3.9 9.9 3.4 14,518 15,326 9.583 2.293 1.236 13 2.0 5.8 11.8 5.2 13,496 14,194 9.510 2.470 1.650 14 2.0 7.8 13.8 6.6 12,307 13,802 9.418 2.623 1.890 15 2.0 9.8 15.8 8.4 12,565 13,363 9.439 2.758 2.125 Universal Model Calculations - US Customary Units Braun Sample ID: 1 Station: TP-7 SUMMARY OUTPUT Regression Statistics Multiple R R Square Adjusted R Square Standard Error Observations 0.897916763 0.806254513 0.773963599 0.085509723 15 ANOVA ax5 Value t-Stat kl k2 k3 10724.224 0.332780325 -0.328339683 51.11372 4.526286657 -7.010227266 R-sqr Adj. 0.7739636 Std Err 0.0855097 or 8.93% df SS MS F Significance F Regression Residual Total 2 0.365134451 0.1825672 24.968463 5.28919E-05 12 0.087742953 0.0073119 14 0.452877404 Project: B1702069 Coefficients Standard Error t Stat P-value Lower 95% 9.28026037 0.332780325 -0.32833968 Upper 95% Lower 95.0% Upper 95.0% Intercept X Variable 1 X Variable 2 0.181561043 51.11372 2.065E-15 0.073521708 4.5262867 0.0006942 0.046837238 -7.010227 1.414E-05 8.884672839 0.172590285 -0.430389258 9.675847901 0.492970365 -0.226290108 8.884672839 9.675847901 0.172590285 0.492970365 -0.430389258 -0.226290108 Universal Model Graph - US Customary Units Braun Sample ID: 1 Station: TP-7 Project: B1702069 26,000 24,000 22,000 20,000 18,000 ▪ 16,000 o. 14,000 • 12,000 ° 10,000 8,000 6,000 4,000 2,000 0 1 0 -------------1 ---------'• —0-6 psi —1111--4 psi —A— 2 psi 0 Predicted 6 psi 0 Predicted 4 psi — Predicted 2 psi ---i • 0 n A A 0 2 3 4 5 6 Deviator Stress, psi 7 8 9 10 0. 0 U)CD U 0 Zt- 0 7.4 I- CD CD z < 0_ I .7tC— cs, 0_ in 0 0 (.0 0 0 0 U) r Z, I 0 CD U) c=5 0 IPE Inland 3012 Spokane Telephone: Fax: 509-290-5734 Pacific Engineering North Sullivan Road, \ , VA 509-209-6262 99216 Valley. Company Suite C PROJECT PROJECT MOISTURE NAME LOCATION Proposed -DENSITY RELATIONSHIP Street Improvements CLIENT PROJECT NAI Black NUMBER 16-249D Spokane Valleys WA DRY DENSITY, pcf V 00 00 CO CO CD 0 _. __.a N.3 N.) 0..) 01 CD 01 0 01 CD (J1 CD 01 0 01 CD Vi .—, 1 \ \ Sample Description Test Method ID of Material Maximum Optimum TEST Dry Water ATTERBERG LL Curves for TP-7 \ \ \ \ \ SANDY LEAN CLAY(CL) ASTM D1557 Method A RESULTS Density Specific Content of 100% Gravity LIMITS PL 110.2 PCF 14.3 % \ PI \ i i \ R \ Saturation Equal to: 2.80 2.70 2.60 \ \ _I I I I 5 10 15 20 25 WATER CONTENT. % 30 35 40 45 REPORT 9 Full-Scale Drywell Testing, dated June 28, 2016 IPEC Inland Pacific Engineering Company Geotechnical Engineering and Consulting August 22. 2017 Project No. 16-249A NAI Black c/o Mr. Bryan Walker 107 South Howard Suite 500 Spokane, WA 99201 Re: Addendum to Full-Scale Drywell Testing Proposed Stormwater Management Facility 4403 South Dishman-Mica Road Spokane Valley, WA Dear Mr. Walker: As you authorized, we have completed a full-scale drywell test on the diywell installed at the above-referenced site in Spokane Valley, Washington. The purpose of the testing was to establish a design flow rate. This addendum provides our recommendations for a design infiltration rate for proposed gravel galleries between the drywells. AVAILABLE INFORMATION We were provided a topographic survey for the project site by Whipple Consulting Engineers, Inc. (WCE). This topographic survey showed the existing roadways. existing structures, property lines, and existing ground surface elevation contours. This plan was prepared by WCE and was dated November 7, 2013. The site was used as a golf course prior to our evaluation. The site is relatively level with some elevated golf greens and excavated areas for water hazards. The site is primarily grass-covered with scattered trees along the fairways and pine trees in the undeveloped area to the northwest. The clubhouse building is present at the southwest corner. In addition, we performed a preliminary geotechnical evaluation for the property in December 2013. The results of that evaluation. along with our opinions and recommendations. are summarized in our Preliminary Geotechnical Evaluation dated December 31, 2013. P.O. Box 1566, Veradale, WA 99037 Phone 509-209-6262 Addendum to Full-Scale Drywell Testing Painted Hills Golf Course Spokane Valley, WA Inland Pacific Engineering Company Project No. 16-249A 4403 South Dishman-Mica Road August 22, 2017 Page 2 We also performed a geotechnical evaluation for certification of the existing levee along Chester Creek in April 2014. The results of that evaluation are summarized in our Geotechnical Evaluation report dated February 12, 2015. Lastly, we performed a geotechnical evaluation in July 2015 consisting of ten 50-foot borings in the south half of the property. The results of that evaluation are summarized in our Geotechnical Evaluation Phase 2 report dated July 23, 2015. FIELD EVALUATION A geotechnical engineer from Inland Pacific Engineering Company (IPEC) performed a full-scale drywell test on the Type 2 drywell (double depth) on May 6, 2016. The drywell test was performed in accordance with the Spokane Regional Stormwater Manual, Appendix 4B procedures. The drywell was installed at the location shown on Figure 3 (attached). ANALYSIS AND RECOMMENDATIONS We calculated a design outflow rate for the existing drywell to be 1.05 cfs for design. This recommended design outflow rate included a safety factor of 1.1 as required by the SRSM. Using this design outflow rate and assuming a typical infiltration area of 600 square feet for a Type 2 drywell, we recommend using a design infiltration rate of 1.8 x 10-3 cubic feet per second per square foot (cfs/ft). This recommended infiltration rate also includes a safety factor of 1.1. REMARKS This report is for the exclusive use of the addressee and the copied parties to use in design of the proposed project and to prepare construction documents. In the absence of our written approval, we make no representations and assume no responsibility to other parties regarding this report. The data, analyses, and recommendations may not be appropriate for other structures or purposes. We recommend that parties contemplating other structures or purposes contact us. Services performed by the geotechnical engineers for this project have been conducted in a manner consistent with that level of care ordinarily exercised by members of the profession currently practicing in this area under similar budget and time restraints. No warranty, expressed or implied, is intended or made. Addendum to Full-Scale Drywell Testing Painted Hills Golf Course Spokane Valley, WA Inland Pacific Engineering Company GENERAL REMARKS Project No. 16-249A 4403 South Dishman-Mica Road August 22, 2017 Page 3 It has been a pleasure being of service to you for this project. If you have any questions or need additional information, please do not hesitate to call me at (509) 209-6262 at your convenience. Sincerely, Inland Pacific Engineering Company Paul T. Nelson, P.E. Principal Engineer J ETt;;-. WAS; + °. JET NFL 111 <1/4's, 37228 m 6b/s-reccc-,&C, u/ON At- - IPEC Inland Pacific Engineering Company Geotechnical Engineering and Consulting June 28. 2016 Project No, 16-249A NAI Black c/o Mr. Bryan Walker 107 South Howard Suite 500 Spokane, WA 99201 Re: Full-Scale Drywell Testing Proposed Stormwater Management Facility 4403 South Dishman-Mica Road Spokane Valley, WA Dear Mr. Walker: As you authorized, we have completed a full-scale drywell test on the drywell installed at the above-referenced site in Spokane Valley, Washington. The purpose of the testing was to establish a design flow rate. This report summarizes the results of our site investigation, engineering analyses and recommendations. AVAILABLE INFORMATION We were provided a topographic survey for the project site by Whipple Consulting Engineers, Inc. (WCE). This topographic survey showed the existing roadways, existing structures, property lines, and existing ground surface elevation contours. This plan was prepared by WCE and was dated November 7, 2013. The site was used as a golf course prior to our evaluation. The site is relatively level with some elevated golf greens and excavated areas for water hazards. The site is primarily grass-covered with scattered trees along the fairways and pine trees in the undeveloped area to the northwest. The clubhouse building is present at the southwest corner. In addition, we performed a preliminary geotechnical evaluation for the property in December 2013. The results of that evaluation, along with our opinions and recommendations, are summarized in our Preliminary Geotechnical Evaluation dated December 31. 2013. P.O. Box 1566, Veradale, WA 99037 Phone 509-209-6262 Full-Scale Drywell Testing Painted Hills Golf Course Spokane Valley, WA Inland Pacific Engineering Company Project No. 16-249A 4403 South Dishman-Mica Road June 28, 2016 Page 2 We also performed a geotechnical evaluation for certification of the existing levee along Chester Creek in April 2014. The results of that evaluation are summarized in our Geotechnical Evaluation report dated February 12, 2015. Lastly, we performed a geotechnical evaluation in July 2015 consisting of ten 50-foot borings in the south half of the property. The results of that evaluation are summarized in our Geotechnical Evaluation Phase 2 report dated July 23, 2015. FIELD EVALUATION A geotechnical engineer from Inland Pacific Engineering Company (IPEC) performed a full-scale drywell test on the Type 2 drywell on May 6, 2016. The drywell test was performed in accordance with the Spokane Regional Stonnwater Manual, Appendix 4B procedures. ANALYSIS AND RECOMMENDATIONS We calculated a design outflow rate for the existing drywell using the results of the recent and previous laboratory tests and the procedures described in the SRSM manual, Appendix 4B (Full- Scale Drywell Test Method). Based on the test performed, we recommend using a design flow rate of 1.05 cfs for design. This recommended design outflow rate includes a safety factor of 1.1 as required by the SRSM. REMARKS This report is for the exclusive use of the addressee and the copied parties to use in design of the proposed project and to prepare construction documents. In the absence of our written approval, we make no representations and assume no responsibility to other parties regarding this report. The data, analyses, and recommendations may not be appropriate for other structures or purposes. We recommend that parties contemplating other structures or purposes contact us. Services performed by the geotechnical engineers for this project have been conducted in a manner consistent with that level of care ordinarily exercised by members of the profession currently practicing in this area under similar budget and time restraints. No warranty, expressed or implied, is intended or made. Full-Scale Drywell Testing Painted Hills Golf Course Spokane Valley, WA Inland Pacific Engineering Company GENERAL REMARKS Project No. 16-249A 4403 South Dishman-Mica Road June 28, 2016 Page 3 It has been a pleasure being of service to you for this project. If you have any questions or need additional information, please do not hesitate to call me at (509) 209-6262 at your convenience. Sincerely, Inland Pacific Engineering Company Paul T. Nelson, P.E. Principal Engineer Attachments: Figure 1, Site Location Map Figure 2, MRCS Map Laboratory Test Results Full-Scale Drywell Test Results NS\' NE( '90 wAs , A As<0 -V 0,0, w Zct LU ILI '<k-53.e7/40-(33N17S22:1-'74Q *,\