Loading...
Appendix_DAPPENDIX D – STANDARD SUBDIVISION ENVIRONMENTAL EFFECTS ANALYSIS NATURAL ENVIRONMENT (GROUND AND SURFACE WATER) Under the Standard Subdivision Alternative, as with Alternative 2a, the widening of Thorpe Road to meet City road standards will result in an additional 15 feet of the main channel of Chester Creek to be bridged by the new roadway surface. As described for Alternative 2a, under the Standard Subdivision Alternative floodwater that enters the project site will be collected in a series of pipes and swales and will infiltrate into the Spokane Rathdrum Prairie aquifer via an engineered infiltration basin. No change in volumes of water that reach the aquifer via the project site are anticipated to change under the Standard Subdivision Alternative. As described for Alternative 2a, under the Standard Subdivision Alternative there would be no direct impact to the channel of Chester Creek from the widening of Thorpe Road. Under the Standard Subdivision Alternative there would be no impact to the Spokane Rathdrum Prairie aquifer. Water that currently recharges the aquifer would continue to recharge through permeable areas and through the infiltration pond installed at the northern limits of the site. Stormwater quality and quantity management methods consistent with those identified for Alternative 2a would be employed with be employed. Because on-site and regional development will be required to employ stormwater quality and quantity management measures consistent with the SRSM, no cumulative effects are anticipated. BUILT ENVIRONMENT (LAND USE AND FLOOD HAZARD AREAS) Under the Standard Subdivision Alternative, the approach to controlling and managing floodwaters, and meeting compensatory storage requirements will be the same as the approach proposed under Alternative 2a. Management and control of floodwaters will be achieved on-site through a combination of enhanced conveyance facilities (culverts) and infiltration galleries. Development areas where future roads and buildings will be located will be elevated above the 100-year floodplain through the placement of imported fill. As proposed under Alternative 2a, The Standard Subdivision Alternative proposes to modify existing floodplain areas through a CLOMR, the preliminary FEMA remap authorization before a LOMR is finalized. As described for Alternative 2a, the sources of floodwater under The Standard Subdivision Alternative remain unchanged. The potential for floodwater to enter the site from the unnamed tributary to Chester Creek northeast of the project site will be eliminated due to the placement of the existing Gustin Ditch into a pipe that connects directly to the triangle pond which would serve as a detention basin. Under the Standard Subdivision Alternative, as under Alternative 2a, floodwaters that leave the Chester Creek channel south of the site will no longer flow over Thorpe Road or inundate the southern portion of the project site. Under this alternative, unlike under Alternative 2a, the southern portion of the project site would be filled for residential lots and would not be available to receive floodwater because the park in this vicinity would be omitted from the design. As described for Alternative 2a, on-site and off-site flood conveyance and storage improvements completed under The Standard Subdivision Alternative would also remove off-site areas from the 100- year floodplain. The area east of Madison Road currently designated as 100-year floodplain would lose its floodplain designation and the potential for ponding in that area would be significantly reduced. Similarly, the potential for flooding on the property to the northeast of the project site from the unnamed tributary to Chester Creek near SR 27 due to replacement of the Gustin Ditch with a 36-inch pipe, and the deepening and addition of drywells to the bottom of the triangle pond. The 100-year floodplain designation would be removed from the currently designated floodplain between the northeast corner of the project site and SR 27, including the Gustin property. The changes in floodplain designation proposed under the Standard Subdivision Alternative would allow new development in areas, both on-site and off-site, that had been previously subject to development restrictions due to 100-year flood mapping. TRANSPORTATION The Standard Subdivision Alternative proposes the development of 543 residential lots and would not include any new commercial retail or multi-family uses within the project. The Alternative would, however, continue to include the operation of the former golf course clubhouse as a 4,000 SF restaurant. Using the ITE Trip Generation Manual, 9th Edition designation (Land Use Code #210) for single family residential units, an average of 9.52 vehicular trips per day and one PM peak hour trip per unit is assumed. Therefore, a total of 5,169 ADT and 543 PM peak hour trips are assumed to occur from the residential use under the Standard Subdivision Alternative. Because the 2016 TIA included trips estimated from re-use of the golf course clubhouse, those trips have also been added to the estimated trip generation of the standard subdivision to ensure that the baseline assumptions of traffic impacts of Alternatives 2a and 3 are consistent. As noted in Table 3-8 below, The Standard Subdivision Alternative generates approximately 317 fewer average daily trips, but generates approximately 28 more PM peak hour trips. This is due to the higher PM peak hour trip generation of the single-family residential units and the fact that no internalization trip reduction factor is applied with The Standard Subdivision Alternative because no commercial uses would be included. Table 1: ADT and PM Peak Hour Trip Comparison – Alternatives 2a and 3 Alternative ADT PM Peak Hour Trips Alternative 2a – PRD (inc. 4,000 GSF restaurant) 5,846 545 Standard Subdivision Alternative – Standard Subdivision (inc. 4,000 GSF restaurant) 5,529 573 *Trip counts include 360 ADT and 30 PM peak hour trips associated with the 4,000 square foot restaurant operating at the former golf clubhouse. Construction-related Impacts Like Alternative 2a, the Standard Subdivision Alternative would also require a substantial amount of fill material to bring development areas above the 100-year base flood elevation. The Standard Subdivision Alternative would require more fill than Alternative 2a, primarily due to the filling of the open space area located just north East Thorpe Road. The total required fill volume with The Standard Subdivision Alternative is approximately 574,122 CY. Using the same 15 percent shrink/swell factor applied to determine the amount of “loose” material that would need to be imported to the site under the Standard Subdivision Alternative, it is estimated that a total of approximately 660,240 CY of fill material would need to be imported under The Standard Subdivision Alternative. Based on an average dump truck volume of approximately 30 CY, it is estimated that 22,008 dump truck deliveries would be required to bring this fill material to the site. Assuming this material is delivered to the site over a four- year period, with 280 work days per year, it is assumed that approximately 20 truck deliveries would occur per day or approximately 40 truck trips (one trip to the site and one return trip) would occur per day over the duration of the site grading activities. The haul route for these dump trucks will be via Dishman-Mica Road, a Principal and Minor Arterial, that experiences a total ADT of approximately 22,700 trips near Appleway Avenue and 4,800 ADT near Thorpe Road. Therefore, the dump truck- related trips are estimated to represent less than one percent of the ADT of this facility. ENVIRONMENTAL ELEMENTS NOT ANALYZED IN DETAIL Air Quality Impacts to air quality under The Standard Subdivision Alternative will be similar to those described for Alternative 2a with the following exceptions:  The Standard Subdivision Alternative provides a greater number of single-family residences than Alternative 2a, with 543 total single-family residences compared to 300 single family residences in Alternative 2a. The additional single-family residences are more likely to be a source of fine particulates from wood burning stoves.  The Standard Subdivision Alternative does not incorporate 30% of the gross site area to public open space, therefore providing less area that can serve as a “carbon sink.”  Construction-related impacts to air quality will likely be greater with the Standard Subdivision Alternative due to the greater degree of imported fill material required. Aesthetics Under the Standard Subdivision Alternative, most of the field and open space areas on the site would be converted to urban development. As a standard subdivision, the project would not be subject to the 30 percent open space requirement found in SVMC Section 19.50.060, and therefore resulting open spaces would primarily be limited to the riparian buffer along Chester Creek, landscape areas and the flood basin located on the north side of the site. Cumulative Effects City and County development standards governing screening, setbacks, landscaping, light, glare, building height and other provisions are expected to adequately address the aesthetic effects of individual development projects. Therefore, no significant cumulative aesthetic effects are expected to result when considering the action alternatives in conjunction with other potential development in the project vicinity. Biological Resources Environmental Consequences Riparian buffer impacts would occur with the Standard Subdivision Alternative. The riparian buffer adjacent to the restaurant parking lot will be reduced by up to 25% (for a minimum buffer of 75-feet) in the location of a proposed parking lot expansion. This would result in an approximately 3,665 SF buffer reduction/impact. Like Alternative 2a, the Standard Subdivision Alternative also includes a 1,383 SF impact area resulting from the Thorpe Road expansion. These are the only two areas of permanent riparian buffer impacts under the Standard Subdivision Alternative and result in a total impact area of approximately 5,048 SF. The Standard Subdivision Alternative would also involve temporary riparian impacts resulting from the placement of fill material on the east side of the streambank to bring land areas farther to the east above the 100-year base flood elevation and suitable for residential development. The buffer in this area is currently planted non-native golf course turf grass and is almost totally devoid of woody vegetation. No permanent loss of buffer would occur in this area. Existing cart paths would be removed and new trails of approximately the same width would be constructed as a replacement and for community use. Fill material placed on the east stream bank will cover an approximately 104,132 SF of area. This area will be replanted with native grasses, trees and shrubs, representing a significant enhancement over existing conditions. Environmental Health Similar to Alternative 2a, the Standard Subdivision Alternative has the potential to generate environmental health effects from dust and construction equipment emissions and from construction noise. Geology As described for Alternative 2a, site grading activities associated with the Standard Subdivision Alternative will cover most of the site with imported fill. The property will be graded to create the streets, drainage ponds/swales, and areas future residences. The Standard Subdivision Alternative is expected to require 574,122 CY of fill material, which will require the import of approximately 660,240 CY of “loose” fill material prior to compaction on the site. Approximately 25% of the site would be covered with impervious surfaces after completion of the project. As described for Alternative 2a, due to the placement of fill and site development features under the Standard Subdivision Alternative the opportunity for surface water and precipitation to recharge the underlying aquifer will be limited to the proposed infiltration basin, roadside swales, and dry wells. Some erosion from wind and minor erosion from rain could occur on-site during construction elements. Because of the flatness of the site, the potential for surface water erosion is limited and would be localized to the area of work. Historic, Cultural, and Archaeological Resources Areas of site disturbance for the Standard Subdivision Alternative would occur within the same site limits as those evaluated in the cultural resources survey. As a consequence, no impacts to Native American or historic-era cultural materials are expected to result from the Standard Subdivision Alternative. However, site construction activities will occur under the guidance of an IDP as outlined in Appendix A of the Cultural Resources Survey to ensure that any potential inadvertent discovery is promptly addressed. Noise The Standard Subdivision Alternative noise levels will increase beyond current noise levels both during the construction phase and indefinitely once the project construction is completed. During the construction phase noise from construction, land clearing, and fill delivery and placement equipment as well as structure construction will increase for the short term. Following completion of construction, noise will be generated by residential traffic and other residential sources including yard maintenance equipment, domestic pets, occupants, and park use for the long term. The increase in population under the Standard Subdivision Alternative would likely lead to noise levels that are higher than current levels. It is unlikely that the increase would be measurable, but it may be perceived by residents in terms of the frequency to which they experience noise disturbance. Public Services The Standard Subdivision Alternative is anticipated to create 543 single-family residential units, which would result in approximately 1,358 new residents at full buildout of the community. This alternative would not include any new commercial uses and no change would occur at the clubhouse building, which is assumed to continue to operate as a restaurant. As the use of the clubhouse would not change, the use of the clubhouse is not expected to have a change in impact on public services. The following paragraphs summarize the anticipated effects of the Standard Subdivision Alternative on schools, parks, fire, public safety, water and sanitary sewer services. Schools Based on the U.S. Census Bureau American Community Survey (ACS) 5-year estimate data, approximately 15.2% of Spokane Valley’s population is between the ages of 5 and 17 years old. Extrapolating this number to the Standard Subdivision Alternative, an estimated 206 students would reside within the project upon the completion of the Standard Subdivision Alternative. While the precise cohort of elementary school, middle school and high school students is not known, if general student population were proportionately distributed to the number of grades in elementary (six grades), middle school (three grades), and high school (four grades), it is assumed that the development of the Standard Subdivision Alternative would result in the following increases in student population:  Elementary School – Approximately 9.5 new students per year or 95 total students over the approximately 10-year buildout of the project.  Middle School – Approximately 4.7 new students per year or 47 total students over the approximately 10-year buildout of the project.  High School - Approximately 6.4 new students per year or 64 total students over the approximately 10-year buildout of the project. Fire Because the demands for fire service would be similar to Alternative 2a and the fire district has provided specific development and design requirements for that alternative, there are no anticipated challenges with obtaining fire district service for the Standard Subdivision Alternative. Public Safety It is expected that additional service calls will occur from future residences and businesses within the site, but these uses are not anticipated to create a significant increased demand for public safety services. Per communications with City of Spokane Valley staff, the level of additional activity created under the Standard Subdivision Alternative would not generate a significant impact to public safety services.1 The City regularly reviews large development proposals and, in instances where a significant new user, such as a big-box retail project, creates enough demand to warrant special adjustments in service, the City will make those adjustments to its service contract with Spokane County. However, similar to Alternative 2a, the gradual increase in population resulting from the Standard Subdivision Alternative can be commensurately addressed through regular level-of-service adjustments occurring through the City’s periodic review and adjustment of its public safety contract with the County. Water Due to the fact that the Standard Subdivision Alternative would have a water demand that is very similar to Alternative 2a and Spokane County Water District #3 has acknowledged their ability to serve the project, there are no anticipated impacts or unique challenges to provide water to the site under the Standard Subdivision Alternative. Sanitary Sewer Because the water demand under the Standard Subdivision Alternative would be similar to Alternative 2a and Spokane County Environmental Services has acknowledged their ability to serve Alterative 2, there are no anticipated impacts or unique challenges to provide sewer service under the Standard Subdivision Alternative. Cumulative Effects There are no known cumulative effects from other on-going projects or activities that, when considered in conjunction with the action alternatives, could result in any discernible effects on public services. Recreation Environmental Consequences The Standard Subdivision Alternative is anticipated to create 543 single-family residential units, which would result in approximately 1,358 new residents at full buildout of the community. Based on the City’s comprehensive plan target of 1.92-acres of parks area per 1,000 residents, the Standard Alternative would generate the need for approximately 2.61 acres of park area. Cumulative Effects The City conducts periodic reviews of its parks and recreation needs for the broader community and last updated its Parks and Recreation Master Plan in 2013. Through regular review and update of the community plan, the City anticipates and plans for necessary recreational needs throughout the community. Therefore, any cumulative effects of population growth within the broader community have been considered and integrated with the City’s parks and recreation system planning efforts. 1 Pers comms with Morgan Koudelka, City of Spokane Valley, January 14, 2019.