14 ATTACHMENT 6 - Appendix A - E

City of Pleasanton–Spotorno Ranch Reduced Development Project Initial Study/Consistency Checklist Environmental Checklist FirstCarbon Solutions 163 https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/2148/21480021/Consistency Checklist/21480021 Spotorno Ranch Consistency Checklist ScreenCheck.docx number of people assumed to live in a single-family house (3), so an ADU would use 66 percent of the average single-family usage. This provides an estimate of 2,425 GPD for the 22 ADUs, and a total estimate of 6,099 GPD of wastewater generated by the proposed project. As discussed previously, the City of Pleasanton has an average annual wastewater flow of approximately 6.0 MGD and a wastewater treatment capacity of 8.5 MGD, leaving 2.5 MGD of remaining capacity.51 The 6,099 GPD of wastewater generated by the proposed project would equate to a nominal increase in the City’s remaining 2.5 MGD capacity. The wastewater generated by the proposed project would be within the permitted capacity of the DSRSD and would not exceed what was previously analyzed in the 1998 HVSP FEIR. A 2016 Happy Valley Water and Sewer Study was conducted by RMC Water and Environment and determine that the existing wastewater structure was sufficient to accommodate additional flows from the buildout of the HVSP.52 The project does not propose any industrial or commercial uses where pollutant levels or wastewater volumes are typically high. Therefore, the proposed project would not exceed wastewater treatment requirements established by the San Francisco Bay RWQCB. Additionally, the project applicant would be responsible for its fair share of the City’s water system master plan improvements, and the proposed project would comply with General Plan Water Programs VI-4.5 and 4.6 to reduce water use. Therefore, the proposed project would not result in any peculiar effects related to wastewater and would not result in new or more severe impacts beyond what was previously analyzed in the 1998 HVSP FEIR. Stormwater The project site consists of mostly undeveloped land and does not include any existing utility infrastructure. Existing water, wastewater, and stormwater infrastructure is located immediately adjacent to the project site, within Alisal Street and Westbridge Lane. The construction of new stormwater drainage facilities would connect to this existing infrastructure. Development of the proposed residential units would result in a net increase of impervious surfaces consisting of buildings, paved roadways, and driveways. Increased runoff volume could exceed the capacity of downstream drainage components, causing localized flooding. As discussed previously, there are areas in the project vicinity where flooding occurs because of deficient stormwater systems. According to the HVSP, the crossroad drain lines along the Spotorno Flat Area frontage of Alisal Street need to be replaced with properly sized culverts. In addition, roadside drainage along the Spotorno Flat Area frontage of Alisal Street needs to be improved. As discussed in Appendix J, MM G1, MM G4, and MM G5, as outlined in the 1998 HVSP FEIR, included as Appendix A of this document, would be incorporated into the proposed project as conditions of approval. The proposed project would be served by existing stormwater facilities maintained by the City of Pleasanton. The City’s storm drainage system is composed mostly of curb inlets, underground pipes, local channels, and natural swales. Storm drainage pipes varying from 24 to 36 inches would run 51 City of Pleasanton. 2009. 2005 General Plan 2025, Chapter 8 Water Element. Website: https://www.cityofpleasantonca.gov/civicax/filebank/blobdload.aspx?BlobID=23911. Accessed February 17, 2021. 52 RMC Water and Environment. November 21, 2016. Happy Valley Water and Sewer Study Technical Memorandum.