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2006, 02 Flood Insurance Study Chester Creek & TributaryChester Creek Flood Insurance Study DRAFT Spokane County, Washington Key to Cross -Section Labeling oc4c ciC- Key to Cross -Section Labeling FLOOD INSURANCE STUDY Prepared by: Community Name: SC: WEST Consultants, Inc. Spokane County TC: Date Prepared: State: Washington SC: February 2006 FEMA CID: TC: Stream Name: Chester Creek and Tributary Run Date: TECHNICAL EVALUATION STUDY CONTRACTOR CONTRACTOR uter Cross -Section CompEPA Reach Cross -Section Stationing Draft FIS (RAS) No. Final FIS Chester Creek - Main Channel A 4201.7 B 4787.8 C 5319.4 D 5836.2 E 6348.0 6738.0 F 6788.0 G 7197.6 H 7685.8 I 8194.9 8714.4 K 9215.5 9340.0 L 9395.0 Study Contractor: WEST Consultants, Inc. Page 33 Chester Creek Flood Insurance Study Spokane County, Washington DRAFT Study Contractor: WEST Consultants, Inc. Page 34 M 9676.0 N 9916.0 0 10162.0 P 13616.0 Q 14037.1 R 14344.1 S 14412.7 14460.8 T 14534.3 U 14583.4 V 15031.5 W 15266.6 X 15707.7 T 16067.4 16140.0 Y 16170.0 Z 16212.1 AA 16684.6 AB 17202.3 AC 17443.6 AD 17655.0 .. AE 18180.1 AF 18716.0 18755.8 AG 18804.3 AH 18849.8 Al 19395.1 19427.6 AJ 19444.0 AK 19460.2 AL 19493.4 AM 19887.6 AN 20263.2 20427.8 AO 20492.8 AP 20554.7 Study Contractor: WEST Consultants, Inc. Page 34 Chester Creek Flood Insurance Study Spokane County, Washington DRAFT Study Contractor: WEST Consultants, Inc. Page 35 AQ 20779.1 20828.3 20838.5 20868.1 20895.9 20928.9 20967.2 20976.0 AR 21013.8 AS 21231.7 AT 21456.4 21481.4 21515.0 21548.4 21584.0 AU 21607.0 AV 21924.1 AW 22423.7 AX 22972.9 23005.8 AY 23050.2 AZ 23090.9 BA 23446.3 BB 23887.6 BC 24429.2 24473.4 BD 24501.5 BE 24573.9 BF 24966.5 24998.8 25012.2 BG 25049.9 BH 25292.5 BI 25783.0 25880.9 25941.8 Study Contractor: WEST Consultants, Inc. Page 35 Chester Creek Flood Insurance Study Spokane County, Washington DRAFT Study Contractor: WEST Consultants, Inc. Page 36 BJ 25989.6 BK 26225.2 26256.3 26281.7 BL 26315.2 BM 26876.3 BN 27314.8 27360.6 27392.3 BO 27409.9 BP 27594.4 BQ 28139.2 28173.9 BR 28268.5 BS 28363.2 28441.8 BT 28488.5 BU 29140.9 BV 29681.6 BW 30242.2 30497.0 BX 30506.3 BY 30675.0 30747.8 30797.0 BZ 30811.8 CA 31471.5 CB 31927.4 CC 32539.9 CD 33402.9 CE 34088.5 CF 34604.2 34625.5 CG 34675.9 CH 34693.8 CI 35297.7 Study Contractor: WEST Consultants, Inc. Page 36 Chester Creek Flood Insurance Study Spokane County, Washington DRAFT Study Contractor: WEST Consultants, Inc. Page 37 CJ 35946.6 CK 36421.2 CL 36928.8 CM 37454.6 CN 37835.3 37906.5 CO 37973.7 CP 38025.9 Chester Creek - West of Borrow Pit A 11069.0 B 11616.0 C 11721.0 D 11942.0 E 12473.0 F 12974.0 G 13067.0 H 13166.0 I 13229.0 J 13317.0 K 13396.0 L 13616.0 M 14037.0 N 14344.0 0 14412.0 Chester Creek - Dredge Channel A 16212.0 B 16684.0 C 17202.0 D 17443.0 Chester Creek - Golf Course A 20779.0 B 21013.0 C 21128.0 D 21229.0 E 21385.0 21409.0 21431.0 F 21445.0 21456.0 21481.0 21515.0 G 21548.0 H 21924.0 I 22423.0 Study Contractor: WEST Consultants, Inc. Page 37 Chester Creek Flood Insurance Study DRAFT Spokane County, Washington Study Contractor: WEST Consultants, Inc. Page 38 J 22972.0 23005.0 K 23050.0 L 23090.0 M 23446.0 N 23887.0 Chester Creek - Without Levee DS of Bowdish Road AP 16684.6 AQ 17202.3 AR 17443.6 AS 17655.0 AT 18180.1 AU 18716.0 Chester Creek - Without Levee US of Bowdish Road Al 19395.1 19427.6 AJ 19444.0 AK 19460.2 AO 19493.4 AM 19887.6 Unnamed Tributary to Chester Creek A -1303.0 B -1019.0 C -880.0 D -466.0 E -89.0 F 1.0 G 149.0 H 343.0 383.0 J 472.0 K 576.0 L 651.0 M 918.0 N 1472.0 1510.0 O 1528.0 P 1557.0 Q 1963.0 1989.0 2080.0 R 2100.0 2110.0 S 2120.0 T 2651.0 U 3126.0 V 3617.0 Study Contractor: WEST Consultants, Inc. Page 38 Chester Creek Flood Insurance Study Spokane County, Washington DRAFT Study Contractor: WEST Consultants, Inc. Page 39 W 4127.0 X 4623.0 4665.0 Y 4704.0 Z 4750.0 AA 5165.0 AB 5676.0 AC 6117.0 6154.0 AD 6239.0 AE 6274.0 AF 6553.0 AG 7086.0 7121.0 AH 7143.0 7169.0 Al 7186.0 AJ 7220.0 Unnamed Tributary Without Levee DS of Pines Road A -1303.0 B -1019.0 C -880.0 D -466.0 E -89.0 F 1.0 G 149.0 H 343.0 1 383.0 J 472.0 K 576.0 L 651.0 M 918.0 N 1472.0 1510.0 0 1528.0 P 1557.0 Unnamed Tributary Without Levee US of Pines Road 1511.0 1782.0 S 2120.0 T 2651.0 U 3126.0 V 3617.0 W 4127.0 X 4623.0 Study Contractor: WEST Consultants, Inc. Page 39 Chester Creek Flood Insurance Study DRAFT Spokane County, Washington Hydraulic Model Files Index Flooding Source /Stream Name Study Contractor: WEST Consultants, Inc. Hydraulic Model Files Index Chester Creek — Spokane County, Washington FLOOD INSURANCE STUDY File Description File Name Chester Creek RAS Model of Chester Creek CCMain.prj Unnamed Tributary RAS Model of Unnamed Tributary to Chester Creek CCTrib.prj Study Contractor: WEST Consultants, Inc. Page 40 Chester Creek Flood Insurance Study DRAFT Spokane County, Washington Draft FIS Report Text FLOOD INSURANCE STUDY REPORT DATA CHECKLIST FLOOD INSURANCE STUDY SPOKANE COUNTY, WA 1.0 INTRODUCTION 1.1 Purpose of Study Community Name: City of Spokane Valley and Unincorporated Spokane County County: Spokane State: Washington 1.2 Authority and Acknowledgments Study Contractor: WEST Consultants, Inc. Subcontractor (if applicable): N/A Contract No.: EMS -2001 -CO -0068 Completion Date (month and year): February 2006 Provider/Agency of Base Map & Address: TerraPoint Base Map Compilation Source: Photographic coverage (1993) Base Map Compilation Scale: Base Map Compilation Date: June 2003 Coordinate System, Projection, Datum: Washington State Plane North NAD 83/91 US Survey Feet, NAVD88, Geiod99 Has base map source been modified? N/A If so, how and where? N/A Any restrictions on release of base map data? N/A If yes, what restrictions apply? N/A 1.3 Coordination Initial Consultation and Coordination Officer's (CCO) meeting date: N/A List attendees and agencies represented at the initial CCO meeting: N/A Intermediate CCO meeting data and attendees (if applicable): N/A List contacts made for purposes of acquiring information: N/A Study Contractor: WEST Consultants, Inc. Page 41 Chester Creek Flood Insurance Study DRAFT Spokane County, Washington 2.0 AREA STUDIED 2.1 Scope of Study Note areas excluded from study, as well as areas of extraterritorial jurisdiction: List the flooding sources studied in detail (detailed study streams should be listed in the same order as they appear in the profiles). If they are also partially studied by approximate methods, provide the limits of detailed study: Chester Creek from 2°' Ave. to S. Sands Road (approximately 7 river miles). Unnamed tributary to Chester Creek from the Painted Hills Golf Course to private drive approximately 0.5 miles upstream of E 46th Ave (approximately 1.7 river miles). List the flooding sources studied by approximate methods: N/A If applicable, discuss streams on which study was terminated where the 100 -year floodplain permanently narrowed to less than 200 feet wide or for which detailed study was ended where the drainage area was less than 1 square mile: N/A 2.2 Community Description Provide a general description of the community's location within the county and state: (See FIS Hydrology Analysis for Chester Creek, Spokane County, WA. WEST, 2004) (See prior Spokane County, Unincorporated Areas Flood Insurance Study. FEMA, 1992) List surrounding communities and their locations with respect to the subject community: (See FIS Hydrology Analysis for Chester Creek, Spokane County, WA. WEST, 2004) (See prior Spokane County, Unincorporated Areas Flood Insurance Study. FEMA, 1992) List other nearby large cities and their locations: (See FIS Hydrology Analysis for Chester Creek, Spokane County, WA. WEST, 2004) (See prior Spokane County, Unincorporated Areas Flood Insurance Study. FEMA, 1992) Briefly describe the community. This description may include patterns of residential and commercial development; the extent and nature of floodplain development; natural features that affect flood hazards in the community; and Study Contractor: WEST Consultants, Inc. Page 42 Chester Creek Flood Insurance Study DRAFT Spokane County, Washington sufficient description of climatic, physiographic, and land use factors to support the discussion of flood problems that follows (Section 2.3). (See FIS Hydrology Analysis for Chester Creek, Spokane County, WA. WEST, 2004) (See prior Spokane County, Unincorporated Areas Flood Insurance Study. FEMA, 1992) 2.3 Principal Flood Problems Include the discharges and recurrence intervals of major floods: (See FIS Hydrology Analysis for Chester Creek, Spokane County, WA. WEST, 2004) (See prior Spokane County, Unincorporated Areas Flood Insurance Study. FEMA, 1992) Give the locations (city and state) of all stream gages for studied streams: No long-term gage records exist for Chester Creek. Limited gage measurements of the flow along Chester Creek were made as part of a previous hydrology investigation (HYDMET, 1997). The gage data were collected near the Dishman-Mica Road crossing of Chester Creek from December 1994 through March 1995 and November 1995 through February 1996. No significant flood events occurred during the period of record. (See FIS Hydrology Analysis for Chester Creek, Spokane County, WA. WEST, 2004) Note any factors that aggravate flood problems: (See FIS Hydrology Analysis for Chester Creek, Spokane County, WA. WEST, 2004) Provide photos of flooding, flood control structures, etc. (with location of photo noted): See Photo Log at the end of this document 2.4 Flood Protection Measures Describe all flood protection structures and floodplain management measures used to reduce potential flood damage: Community and agency concerns about the extent of flooding and uncertainties regarding existing floodplain mapping resulted in the development of a watershed plan for Chester Creek. The goal of that plan was to identify management recommendations for issues of drainage and flooding, water quality, and riparian habitat. Because of that watershed planning effort, projects to construct various improvements along Chester Creek between Thorpe Road and Schaffer Road have been implemented by Spokane County. In 1998, a project to install new culverts and extensive dredging of the channel between Study Contractor: WEST Consultants, Inc. Page 43 Chester Creek Flood Insurance Study DRAFT Spokane County, Washington Thorpe Road and Schaffer Road was implemented. Additionally, as part of a Spokane County improvement project for Dishman-Mica Road, a large volume borrow pit was constructed to act as a retention and infiltration facility for the floodwaters of Chester Creek. (See FIS Hydrology Analysis for Chester Creek, Spokane County, WA. WEST, 2004) Mention all dams, including those affecting the community that lie outside the community: Mention dams within the community used for purposes other than flood control: If levees are mentioned, state whether the levees meet or fail to meet the FEMA 3 - foot freeboard requirement. None of the levees in the project area meet the FEMA 3 -foot freeboard requirement. 3.0 ENGINEERING METHODS (Note any digital methodologies used) 3.1 Hydrologic Analyses Describe the hydrologic analyses for all flooding sources studied in detail: (See FIS Hydrology Analysis for Chester Creek, Spokane County, WA. WEST, 2004 and Chester Creek Flood Insurance Study Hydrology Re- evaluation, WEST, 2008) In a Summary of Discharges table, provide a summary of drainage area -peak discharge relationships for the streams studied by detailed methods. Discharges and drainage areas for each stream should be listed in descending order. Streams should be listed in the same order as flood profiles: Study Contractor: WEST Consultants, Inc. Page 44 Chester Creek Flood Insurance Study DRAFT Spokane County, Washington Location 10 -yr 50 -yr 100 -yr 500 -yr 38025 — Chester Creek 58 89 101 131 26315 — Chester Creek 87 135 155 201 23887 — Chester Creek 75 104 116 144 21515 — Chester Creek 118 139 147 167 24430 — Golf Course 30 54 64 88 20492 — Chester Creek 115 138 148 170 18180 — Chester Creek 113 137 147 169 Storage Area 2 Outlet 60 100 117 155 14412 — West of Borrow Pit 14 26 32 44 SA5 Outflow — Chester Creek 30 40 44 53 SA 7 Outflow — Chester Creek (24th Ave) 25 42 49 67 SA 8 Outflow — Chester Creek (16th Ave) 9 25 32 48 SA 9 Outflow — Chester Creek (8th Ave) 0 0 0 0 7220 - Tributary 7 14 18 28 6553 - Tributary 11 22 28 45 4704 - Tributary 12 24 30 46 472 - Tributary 10 14 16 20 Storage Area 6 Outflow 0 2 4 7 Storage Area 1 Outflow 0 0 0 0 Study Contractor • WEST Consultants, Inc. Page 45 Chester Creek Flood Insurance Study Spokane County, Washington DRAFT Location 10-y50-yr Overbanks n 100 -yr 500 -yr Overflow Elevation (ft) Storage Area 1 2007.19 2007.80 2008.05 2008.64 2009.0 Storage Area 2 2000.81 2001.06 2001.16 2001.78 2000.81 Storage Area 3 1999.99 2000.74 2001.05 2001.78 1999.99 Storage Area 4 2018.30 2019.23 2019.47 2020.03 2025.0 Storage Area 5 1999.99 2000.74 2001.05 2001.78 2001.9 Storage Area 6 2005.00 2009.60 2009.70 2010.00 2009.5 Storage Area 7 1997.14 1997.19 1997.21 1997.26 1996.9 Storage Area 8 1993.54 1993.65 1993.70 1993.78 1993.4 Storage Area 9 1988.54 1990.75 1990.79 1990.86 1992.5 If applicable, discuss methods used to determine stillwater elevations and reference the Summary of Stillwater Elevations table: N/A 3.2 Hydraulic Analyses State how cross sections were developed for all streams studied by detailed methods: Channel geometry were developed from surveys conducted in March 2003. Overbank geometry were developed from topography developed by TerraPoint (2003). Describe how the dimensions of hydraulic structures were determined: Bridge and culvert data were developed from surveys conducted in March 2003. Explain how channel roughness factors (Manning's "n") were assigned. The "n" values for ALL streams studied by detailed methods (channel and overbank areas) should be given: Manning's "n" values were based on a field inspection and aerial photos and are listed in the table below. State how water -surface elevations were obtained for all streams studied by detailed methods: WEST Consultants, Inc. developed a steady flow model of the system using HEC -RAS Version 3.1.3 (HEC, 2005). The HEC -RAS model Study Contractor: WEST Consultants, Inc. Page 46 Main Channel n Overbanks n Chester Creek 0.040 - 0.060 0.016 - 0.100 Unnamed Tributary 0.040 - 0.050 0.040 - 0.080 State how water -surface elevations were obtained for all streams studied by detailed methods: WEST Consultants, Inc. developed a steady flow model of the system using HEC -RAS Version 3.1.3 (HEC, 2005). The HEC -RAS model Study Contractor: WEST Consultants, Inc. Page 46 Chester Creek Flood Insurance Study DRAFT Spokane County, Washington consists of 5 separate reaches with a total of 265 cross-sections and 26 bridges/culverts. State how starting water -surface elevations were obtained for all streams studied by detailed methods: Normal depth was specified at the downstream end of Chester Creek based on the ground slope near the downstream end of the model reach. Three reaches end in storage areas modeled in HSPF as part of the hydrologic analysis. The known water surface elevation from HSPF output was used as the starting water surface elevation for these reaches. Describe the methodology for wave height/runup, lacustrine, ice jam, alluvial fan flooding, and shallow flooding areas (where applicable): N/A If applicable, reference the Transect Descriptions which should include: transect number, location, 100 -year stillwater elevation, and maximum 100 -year wave elevation. N/A If performed, describe the hydraulic analyses for the approximate flooding sources: N/A If applicable, reference the Transect Data Table which should include: Flooding Source (with the affected transects), 10-, 50-, 100-, and 500 -year stillwater elevation, zone designation and Base Flood Elevation. N/A If applicable, reference the Transect Location Map. N/A Specify whether elevations are referenced to NGVD or NAVD or other datum, and give releveling dates, if any. NAVD 88 4.0 FLOODPLAIN MANAGEMENT APPLICATIONS 4.1 Floodplain Boundaries Identify all maps used. Include the scale, contour interval, and type of map (topographic, compiled from aerial photographs, etc.): Maps used are two foot contour interval topographic maps (developed by TerraPoint from LiDAR data) over 1993 aerial orthophotos. Digital files and paper copies of 4 work maps (1" = 400') labeled `Panel A' through `Panel D' have been provided to FEMA. Identify and reference all maps or methods used to delineate floodplain boundaries for approximate flooding sources: N/A Study Contractor: WEST Consultants, Inc. Page 47 Chester Creek Flood Insurance Study DRAFT Spokane County, Washington 4.2 Floodways List streams, if any, for which floodway widths extend beyond the corporate limits: N/A List streams affected by backwater: N/A Provide method used for floodway computations: The Regulatory floodway is defined as the portion of the river and adjacent land area that must remain unobstructed to ensure that the water surface elevation does not cumulatively increase more than one foot above the base flood elevation (BFE). No existing floodway had been previously defined for Chester Creek. Typically, an encroachment analysis is computed from both the left and right channel banks towards the river channel using an "equal conveyance reduction" method. This approach was utilized where appropriate, however floodway analyses were conducted in multiple areas where no channel exists. Notably, the downstream reach of Chester Creek extends approximately 2 miles beyond the end of the channel in the borrow pit at 2r Ave. Downstream of 28th Ave., flood discharges flows through fields as well as residential and commercial areas. In these areas the floodway was routed along existing surface streets where possible to avoid existing structures. Throughout much of the study area and particularly in the upstream reaches the 100 - year water surface is confined within the main channel and therefore typically an energy increase of zero is listed. The Floodway Tables from RAS are shown later in this document. Give reason or reasons why no floodway was delineated for streams or portions of streams: N/A Identify any abnormal procedures (such as state -imposed surcharges of less than 1.0 foot) for floodway delineations: N/A 7.0 OTHER STUDIES Identify and reference all other FISs for contiguous communities and any other published reports or available data dealing with related flooding sources. All disagreements and discrepancies must be noted and resolved: 9.0 BIBLIOGRAPHY AND REFERENCES List references with complete information, including date, place of publication, and scale (as applicable): Study Contractor: WEST Consultants, Inc. Page 48 Chester Creek Flood Insurance Study DRAFT Spokane County, Washington Federal Emergency Management Agency (FEMA) (1992). Flood Insurance Study, Spokane County, Washington, Unincorporated Areas, Revised February 15, 1984. Federal Emergency Management Agency (FEMA) (2002), Guidelines and Specifications for Flood Hazard Mapping Partners, Federal Emergency Management Agency, February 2002. United States Army Corps of Engineers (USACE) (2003), HEC -RAS, River Analysis System Version 3.1.3, May 2005. WEST Consultants, Inc. (2004). "Flood Insurance Study Hydrologic Analysis for Chester Creek, Spokane County, Washington" prepared for FEMA Region X, December 8, 2005. Study Contractor: WEST Consultants, Inc. Page 49 Chester Creek Flood Insurance Study DRAFT Spokane County, Washington Water Surface Profiles Index Study Contractor: WEST Consultants, Inc. Water Surface Profiles Index Chester Creek — Spokane County, Washington FLOOD INSURANCE STUDY Flooding Source Number File Name (*.MDB and /Stream Name of Profile *.DXF extensions) Sheets Chester Creek — Main Channel CC main Chester Creek — West of Borrow Pit CC_wbp Chester Creek — Golf Course Overflow CC_gc Chester Creek — Dredge Channel CC_dch Chester Creek — Without Levee DS of Bowdish Road CC wo ds lev Chester Creek — Without Levee US of Bowdish Road CC wo us lev Unnamed Tributary — Main Channel Trib_main Unnamed Tributary — Without Levee DS of Pines Road Trib_ wo ds_lev Unnamed Tributary - Without Levee US of Pines Road Trib_ wo us_lev Study Contractor: WEST Consultants, Inc. Page 50 Chester Creek Flood Insurance Study DRAFT Spokane County, Washington Floodway Tables Equal conveyance encroachment analyses were conducted (Table 1). No existing floodway had been previously defined for Chester Creek. Typically, an encroachment analysis is computed from both the left and right channel banks towards the river channel using an "equal conveyance reduction" method. This approach was used where appropriate, however floodway analyses were conducted in multiple areas where no channel exists. Notably, the downstream reach of Chester Creek extends approximately 2 miles beyond the end of the channel in the borrow pit at 28th Ave. Downstream of 28th Ave. flood discharges flows through fields as well as residential and commercial areas. In these areas the floodway was routed along existing surface streets where possible to avoid existing structures. Table 1. Floodway table. Flooding Source Floodway Base Flood Water Surface Elevation River Station Cross Section Distance (feet above XS -A) Width (feet) Section Area (square feet) Mean Velocity (feet per second) Regulatory (ft)(NAVD) With Floodway (ft) (NAVD) Without Floodway (ft) (NAVD) Energy Increase (ft) (NAVD) Chester Creek - Main Stem 4202A 517 466 444 0.1 1990.8 1991.8 1990.8 1.0 4788B 1134 197 383 0.1 1990.8 1991.8 1990.8 1.0 5319C 1714 35 73 0.4 1991.0 1991.8 1991.0 0.8 5836D 2219 32 56 0.6 1991.5 1992.1 1991.5 0.6 6348E 2741 30 59 0.6 1991.9 1992.5 1991.9 0.6 6788F 3142 282 531 0.1 1993.7 1993.7 1993.7 0.0 7198G 3554 378 597 0.1 1993.7 1993.7 1993.7 0.0 7686H 4042 220 242 0.2 1993.7 1993.7 1993.7 0.0 8195I 4551 38 21 2.3 1993.8 1993.8 1993.8 0.0 8714J 5071 44 48 1.0 1994.4 1994.9 1994.4 0.5 9216K 5572 36 27 1.8 1995.3 1995.8 1995.3 0.5 9395� 6045 450 379 0.1 1997.2 1997.2 1997.2 0.0 9676 M 6329 417 196 0.3 1997.2 1997.2 1997.2 0.0 9916N 6574 28 26 1.9 1997.3 1997.3 1997.3 0.0 101620 7074 106 43 1.1 1997.5 1998.4 1997.5 0.9 13616 P 10101 90 352 0.4 2001.2 2002.2 2001.2 1.0 14037Q10522 43 87 1.7 2001.2 2002.2 2001.2 1.0 14344R 10829 26 38 3.9 2002.4 2003.0 2002.4 0.6 Study Contractor: WEST Consultants, Inc. Page 51 Chester Creek Flood Insurance Study Spokane County, Washington DRAFT 14413S 10897 67 119 1.2 2002.6 2003.3 2002.6 0.7 14534T 11021 54 71 2.1 2003.8 2003.9 2003.8 0.1 14583 U 11071 42 94 1.6 2003.9 2004.0 2003.9 0.1 15032V 11519 25 52 2.8 2004.0 2004.4 2004.0 0.4 15267W 11754 28 71 2.1 2004.1 2004.8 2004.1 0.7 15708X 12195 91 221 0.7 2004.3 2005.0 2004.3 0.7 16067Y 12555 49 38 3.9 2004.5 2005.0 2004.5 0.5 16212Z 12700 30 41 0.7 2005.7 2006.3 2005.8 0.5 16685 AA 13172 24 69 0.8 2005.9/2005.9 2006.4 2005.9 0.5 17202AB 13690 30 87 1.5 2005.9/2006.2 2006.6 2005.9 0.7 17444AC 13931 24 94 1.6 2006.2/2006.5 2006.8 2006.2 0.6 17655 AD 14143 31 74 2 2006.4/2006.7 2006.9 2006.4 0.5 18180AE 14668 82 118 1.3 2006.7/2007.2 2007.3 2006.7 0.6 18716AF 15204 91 116 1.3 2006.7/2007.8 2007.6 2006.7 0.9 18804AG 15291 22 64 2.3 2007.9 2007.9 2007.9 0.0 18850AH 15337 33 84 1.8 2007.9/2008.0 2008.0 2007.9 0.1 19395AI 15882 30 60 2.5 2008.1/2008.6 2008.6 2008.1 0.5 19444 AJ 15931 19 56 2.7 2008.1/2008.8 2008.8 2008.1 0.7 19460AK 15947 29 72 2.1 2008.1/2008.8 2008.8 2008.1 0.7 19493AL 15980 139 114 1.3 2008.1/2008.9 2008.9 2008.1 0.8 19888AM 16374 132 160 0.9 2008.2/2009.5 2009.1 2008.2 0.9 20263AN 16750 21 48 3.1 2010.1 2010.1 2010.1 0.0 20493AO 16979 32 105 1.4 2010.4 2010.4 2010.4 0.0 20555AP 17041 20 46 3.2 2010.4 2010.4 2010.3 0.0 20779AQ 17265 25 58 2.5 2010.8 2010.8 2010.8 0.0 21014AR 17499 22 44 3.4 2011.2 2011.2 2011.2 0.0 21232AS 17717 26 59 2.5 2011.8 2011.8 2011.8 0.0 21456AT 17941 24 63 2.4 2012.1 2012.1 2012.1 0.0 21607AU 18093 24 39 3.0 2014.7 2015.2 2014.7 0.5 21924AV 18550 240 329 0.4 2014.8 2015.4 2014.8 0.6 22424AW 18857 170 282 0.4 2014.9 2015.5 2014.9 0.6 22973AX 19374 64 29 4.1 2018.5 2019.5 2018.5 1.0 23050AY 19451 26 39 3.0 2020.5 2021.1 2020.5 0.6 23091AZ 19492 35 49 2.4 2020.7 2021.3 2020.7 0.6 23446BA 19847 25 36 3.2 2022.9 2022.9 2022.9 0.0 23888BB 20289 23 36 3.2 2025.2 2025.3 2025.2 0.1 Study Contractor: WEST Consultants, Inc. Page 52 Chester Creek Flood Insurance Study Spokane County, Washington DRAFT 24429BC 20830 10 35 4.4 2028.1 2028.3 2028.1 0.2 24502BD 20903 28 89 1.8 2028.6 2029.0 2028.6 0.4 24574BE 20975 29 35 4.4 2028.7 2029.0 2028.7 0.3 24967BF 21368 29 43 3.6 2031.6 2032.3 2031.6 0.7 25050BG 21451 17 44 3.5 2032.1 2032.8 2032.1 0.7 25293BH 21693 21 45 3.5 2033.3 2033.8 2033.3 0.5 25783 BI 22184 26 44 3.5 2036.2 2036.2 2036.2 0.0 25990 BJ 22390 49 415 0.4 2045.7 2045.8 2045.7 0.1 26225BK 22626 33 250 0.6 2045.7 2045.8 2045.7 0.1 26315 BL 22716 35 217 0.7 2045.7 2045.8 2045.7 0.1 26876BM 23277 18 36 2.8 2045.7 2045.8 2045.6 0.1 27315BN 23716 20 28 3.6 2049.0 2049.0 2049.0 0.0 27410 BO 23811 60 306 0.3 2054.7 2055.7 2054.7 1.0 27594BP 23995 48 186 0.5 2054.7 2055.7 2054.7 1.0 28139BQ 24540 16 17 5.9 2056.9 2056.9 2056.9 0.0 28269BR 24669 30 72 1.4 2058.0 2058.0 2058.0 0.0 28363BS 24764 23 19 5.2 2059.3 2059.3 2059.3 0.0 28489BT 24889 18 41 2.5 2063.1 2063.1 2063.1 0.0 29141 BU 25542 11 15 6.6 2069.4 2069.4 2069.4 0.0 29682BV 26082 27 28 3.7 2079.8 2079.8 2079.8 0.0 30242BW 26643 12 18 5.7 2089.0 2089.0 2089.0 0.0 30506BX 26899 11 22 4.5 2093.8 2093.8 2093.8 0.0 30675BY 27068 13 19 5.4 2096.0 2096.0 2096.0 0.0 30812BZ 27204 17 30 3.3 2097.9 2097.9 2097.9 0.0 31472CA 27864 16 17 5.9 2105.0 2105.0 2105.0 0.0 31927CB 28320 21 29 3.5 2111.9 2111.9 2111.9 0.0 32540CC 28932 30 17 5.8 2126.2 2126.2 2126.2 0.0 33403CD 29795 10 22 4.6 2141.6 2141.7 2141.6 0.1 34089CE 30481 20 21 4.8 2151.1 2151.1 2151.1 0.0 34604CF 30997 12 21 4.8 2159.3 2159.3 2159.3 0.0 34676CG 31068 8 23 4.3 2160.6 2160.6 2160.6 0.0 34694CH 31086 16 26 3.9 2160.8 2160.8 2160.8 0.0 35298 CI 31690 12 16 6.5 2170.8 2170.8 2170.8 0.0 35947 CJ 32339 19 21 4.8 2186.5 2186.5 2186.5 0.0 36421CK 32813 11 17 5.9 2195.7 2195.7 2195.7 0.0 36929C� 33321 12 17 5.9 2207.1 2207.1 2207.1 0.0 Study Contractor: WEST Consultants, Inc. Page 53 Chester Creek Flood Insurance Study Spokane County, Washington DRAFT 37455CM 33847 11 20 5.2 2216.8 2216.8 2216.8 0.0 37835CN 34227 11 15 6.7 2224.6 2224.6 2224.6 0.0 37974CO 34365 13 34 3.0 2228.7 2228.7 2228.7 0.0 38026CP 34418 17 24 4.2 2228.9 2228.9 2228.9 0.0 Chester Creek - West of Borrow Pit 11069 A 344 12 7 4.9 2000.4 2000.8 2000.4 0.4 11616 B 610 21 16 2.0 2003.7 2004.5 2003.7 0.8 11721 C 808 66 179 0.2 2003.7 2004.5 2003.7 0.8 11942 D 1037 39 90 0.4 2003.7 2004.5 2003.7 0.8 12473 E 1556 42 71 0.5 2003.8 2004.6 2003.8 0.8 12974 F 2053 44 23 1.4 2004.3 2004.7 2004.3 0.4 13067 G 2138 44 44 0.7 2004.6 2004.8 2004.6 0.2 13166 H 2182 43 33 1.0 2004.7 2004.8 2004.7 0.1 13229 I 2222 45 30 1.1 2004.7 2004.9 2004.7 0.2 13317 J 2362 44 79 0.4 2004.7 2004.9 2004.7 0.2 13396 K 2442 34 102 0.3 2004.7 2004.9 2004.7 0.2 13616 L 2660 32 142 0.2 2004.7 2004.9 2004.7 0.2 14037 M 3094 29 114 0.3 2004.7 2004.9 2004.7 0.2 14344 N 3393 39 27 1.2 2004.7 2004.9 2004.7 0.2 14412 0 3489 15 8 4.2 2006.1 2006.1 2006.1 0.0 Chester Creek - Dredge Channel 0 A 0 91 113 1.1 2004.8 2005.6 2004.8 0.8 540 B 540 60 85 1.1 2005.3 2006.1 2005.3 0.8 1060 C 1060 63 160 0.1 2005.4 2006.2 2005.4 0.8 1300 D 1300 39 96 0.0 2005.4 2006.2 2005.4 0.8 Chester Creek - Golf Course Overflow 20779 Al 0_ _ _ 2008.1 21013 B1 773_ _ _ 2008.1 21128 C1 961_ _ 2008.5 _ _ 21229 D 1145 35 41 1.6 2008.9 2009.6 2008.9 0.7 21385 E 1425 30 50 1.3 2009.1 2010.0 2009.1 0.9 21445 F 1600 20 28 2.3 2009.3 2010.3 2009.3 1.0 21548 G 1800 45 86 0.7 2013.3 2014.1 2013.3 0.8 21924 H 2123 43 81 0.8 2013.3 2014.2 2013.3 0.9 22423 I 2704 40 67 1.0 2013.5 2014.5 2013.5 1.0 22972 J 3144 14 12 5.3 2014.8 2015.3 2014.8 0.5 23050 K 3287 22 33 1.9 2015.4 2016.2 2015.4 0.8 23090 L 3387 20 25 2.6 2015.7 2016.6 2015.7 0.9 23446 M 3721 20 23 2.8 2018.1 2019.0 2018.1 0.9 23887 N 4318 20 24 2.7 2023.0 2023.8 2023.0 0.8 Unnamed Tributary to Chester Creek -1303 A 0 31 128 0.0 2008.1 2009.1 2008.1 1.0 -1019 B 283 21 17 0.2 2008.4 2009.1 2008.4 0.7 -880 C 422 40 69 0.1 2008.4 2009.1 2008.4 0.7 -466 D 836 46 68 0.1 2008.4 2009.1 2008.4 0.7 Study Contractor: WEST Consultants, Inc. Page 54 Chester Creek Flood Insurance Study Spokane County, Washington DRAFT -89 E 910 40 69 0.1 2008.4 2009.1 2008.4 0.7 1 F 1378 102 658 0.0 2009.7 2010.7 2009.7 1.0 149 G 1525 176 2120 0.0 2009.7 2010.7 2009.7 1.0 343 H 1720 267 3478 0.0 2009.7 2010.7 2009.7 1.0 383 1 1760 280 3362 0.0 2009.7 2010.7 2009.7 1.0 472 J 1849 232 1478 0.0 2009.7 2010.7 2009.7 1.0 576 K 1952 5 7 2.2 2010.0 2010.7 2010.0 0.7 651 L 2028 17 7 2.2 2011.0 2011.1 2011.0 0.1 918 M 2295 10 13 1.3 2011.5 2011.6 2011.5 0.1 1472 N 2849 5 4 4.3 2012.8 2012.8 2012.8 0.0 1528 0 2905 10 18 0.9 2014.3 2014.3 2014.3 0.0 1557 P 2933 8 12 1.3 2014.3 2014.3 2014.3 0.0 1963 Q 3339 9 4 3.8 2019.7 2019.7 2019.7 0.0 2100 R 3485 15 17 1.8 2020.8 2020.8 2020.8 0.0 2120 S2 3509 133 59 0.5 2019.9/2020.9 2020.0 2019.9 0.1 2651 T2 4040 42 31 1.0 2020.8/2023.4 2021.8 2020.8 1.0 3126 U2 4515 67 27 1.1 2024.3/2026.2 2025.2 2024.3 0.9 3617 V2 5006 169 23 1.3 2029.0/2030.7 2030.0 2029.0 1.0 4127 W2 5516 62 17 1.8 2033.5/2035.1 2034.5 2033.5 1.0 4623 X 6028 8 10 3.1 2037.7 2037.7 2037.7 0.0 4704 Y 6109 8 20 1.5 2041.0 2041.0 2041.0 0.0 4750 Z 6155 13 24 1.2 2041.0 2041.1 2041.0 0.1 5165 AA 6570 14 7 4.1 2043.4 2043.4 2043.4 0.0 5676 AB 7082 19 17 1.6 2048.1 2048.2 2048.1 0.1 6117 AC 7522 7 5 5.2 2052.1 2052.1 2052.1 0.0 6239 AD 7645 19 22 1.3 2054.1 2054.1 2054.1 0.0 6274 AE 7679 11 6 4.4 2055.7 2055.7 2055.7 0.0 6553 AF 7958 11 8 3.6 2064.5 2064.5 2064.5 0.0 7086 AG 8491 4 3 5.4 2083.5 2083.5 2083.5 0.0 7143 AH 8548 4 7 2.7 2086.0 2086.0 2086.0 0.0 7186 Al 8592 3 5 3.5 2091.5 2091.5 2091.5 0.0 7220 AJ 8625 6 4 4.7 2092.4 2092.4 2092.4 0.0 Unnamed Tributary - Without Levee DS of Pines Road -1303 A 0 31 128 0.1 2008.1 2009.1 2008.1 1.0 -1019 B 283 21 17 1.0 2008.5 2009.0 2008.5 0.5 -880 C 422 40 70 0.2 2008.6 2009.1 2008.6 0.5 -466 D 836 46 70 0.2 2008.6 2009.1 2008.6 0.5 -89 E 1244 40 70 0.2 2008.6 2009.1 2008.6 0.5 1 F 1400 15 8 2.0 2008.6 2009.1 2008.6 0.5 149 G 1487 15 23 0.7 2008.7 2009.2 2008.7 0.5 343 H 1623 15 15 1.1 2008.7 2009.3 2008.7 0.6 383 1 1649 15 14 1.2 2008.7 2009.3 2008.7 0.6 472 J 1755 15 15 1.1 2008.7 2009.5 2008.7 0.8 576 K 1856 15 16 1.0 2008.7 2009.6 2008.7 0.9 651 L 1985 15 5 3.3 2011.2 2011.5 2011.2 0.3 Study Contractor: WEST Consultants, Inc. Page 55 Chester Creek Flood Insurance Study Spokane County, Washington DRAFT 918 M 2240 15 28 0.6 2011.3 2011.8 2011.3 0.5 1472 N 2873 15 5 3.3 2013.8 2014.2 2013.8 0.4 1528 0 2936 15 12 1.3 2014.1 2014.6 2014.1 0.5 1557 P 2966 15 11 1.4 2014.3 2014.7 2014.3 0.4 1 Cross-section located inside compensatory storage area 2 Floodway is based on combination of with and without levee floodway runs due to perched channel. Width is total width of both runs Study Contractor: WEST Consultants, Inc. Page 56 Chester Creek Flood Insurance Study DRAFT Spokane County, Washington Mapping Information Work maps ArcView/ArcGIS data, and hard copies of work maps, have been provided to FEMA. These shapefiles include: Study Contractor: WEST Consultants, Inc. Mapping Index Chester Creek — Spokane County, Washington FLOOD INSURANCE STUDY File/Exhibit Name Description Disk # or Exhibit # S_BFE.shp BFE Shapefile n/a (email) S_Fld_Haz_Ln.shp Flood Hazard Lines Shapefile n/a (email) S_Wtr_Ln.shp Profile Baseline Shapefile n/a (email) S_XS.shp Cross-section Shapefile n/a (email) Study Contractor: WEST Consultants, Inc. Page 57 Chester Creek Flood Insurance Study DRAFT Spokane County, Washington Elevation Reference Marks GPS control was performed on December 18th and 19th 2002 using a Trimble 4000SSI receiver, a Trimble 4000SSE receiver and a Trimble 4700 receiver. For vertical control National Geodetic Survey (NGS) points K485 and F264 were used. Final error ellipses on the GPS onsite control were within 2mm horizontally and 14mm vertically. Study Contractor: WEST Consultants, Inc. Page 58 Chester Creek Flood Insurance Study DRAFT Spokane County, Washington Miscellaneous Reference Materials There are no additional miscellaneous reference materials for this study. Study Contractor: WEST Consultants, Inc. Page 59 Chester Creek Flood Insurance Study DRAFT Spokane County, Washington Certification This is to certify that all work accomplished in the conduct of this FIS was done in accordance with the Statement of Work and General Provisions of Contract, EMS -2001 -CO -0068, Task TA002, with the Federal Emergency Management Agency, Region X, and all amendments thereto, together with all such modifications, either written or oral, as the Regional PO and/or the Contracting Officer of their representatives have directed, as such modifications affect this contract, and that all such work has been accomplished in accordance with sound and accepted engineering practice within the contract provisions for respective phases of the work. Raymond Walton, PhD, PE Vice -President WEST Consultants, Inc. Study Contractor: WEST Consultants, Inc. Page 60