14 ATTACHMENT 6 - Appendix A - E

City of Pleasanton–Spotorno Ranch Reduced Development Project Project Description Initial Study/Addendum 26 FirstCarbon Solutions https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/2148/21480021/Consistency Checklist/21480021 Spotorno Ranch Consistency Checklist ScreenCheck.docx 2.3.3 - Stormwater The Spotorno Ranch property is mostly undeveloped, and stormwater currently follows natural drainage patterns, either emptying into existing wetlands, flowing off-site via existing drainage ditches and ephemeral streams, or percolating into groundwater aquifers. The proposed project would be subject to the Alameda Countywide Clean Water Program’s C.3 Stormwater Technical Guidance, which require the provision of on-site stormwater treatment facilities. Lots 13–15 (which front onto Westbridge Lane) would be treated by bioretention planters within each lot that would discharge directly to Westbridge Lane through curb drain systems. Stormwater drainage from the balance of the lots and project streets would be conveyed via underground pipes to the treatment pond to be located within Parcel A. The bioretention planters and Parcel A treatment pond would also serve as flow mitigation devices in accordance with the C.3 hydromodification requirements. Overall, the proposed project would create approximately 391,410 square feet of impervious surface, according to the proposed stormwater treatment plan. In accordance with C.3 requirements, a total of 26,650 square feet of bioretention areas would be constructed to provide on-site treatment of stormwater. 2.3.4 - Circulation and Access The 22 proposed residences would be accessed via Alisal Street and Westbridge Lane, both of which are proposed to remain open to through traffic. As shown on Exhibit 3, the residential subdivision would include one primary street, labeled as Spotorno Ranch Drive. Emergency access would be provided via Spotorno Ranch Drive, proposed as a 41-foot, 6-inch-wide public street with an 8-foot paved trail on one side of the road; a 5-foot paved sidewalk on the opposite side of the road, and shoulders on both sides of the road. An 8-foot-wide paved trail with a 2-foot decomposed gravel (DG) buffer on each side would be constructed along Westbridge Lane. That trail would then narrow to approximately 6 feet wide adjacent to the wetland, extending through the open space area and would ultimately connect to the Golf Course loop trail. In addition, an 8-foot-wide paved trail with two feet of DG on each side would be constructed along the east and north sides of Parcel A, continuing across the intersection of Alisal and Spotorno Ranch Drive, then following the southern boundary of the Spotorno Flat Area, behind Parcels 15-16, and 19-22, to connect to the Westbridge Trail. This trail would be called the Spotorno Flats Trail and would be partially located within a dedicated parcel labeled as Parcel B. The project’s proposed circulation is shown in the site plan (Exhibit 3) and the trails are shown in Exhibit 7a and Exhibit 7b. Construction of the Bypass Road contemplated in the HVSP is not proposed as part of this application since the proposed 22 residences with ADUs would not result in traffic conditions that would necessitate the construction of a bypass road. Furthermore, as no development is proposed for HVSP Lots 96 and 97, which were to have 5 and 75 new homes, respectively, the segment of the proposed Bypass Road on the subject Lot 98 is not needed as it would just result in a dead end if built at this time.