RES 211231 Exhibit A - Laserfiche WebLink

Environmental Checklist and City of Pleasanton–10x Genomics Project Environmental Evaluation Initial Study/Mitigated Negative Declaration 96 FirstCarbon Solutions Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/2148/21480024/ISMND/wp/21480024 10x Genomics Project Full Screencheck ISMND.docx Less than significant impact. A significant impact may occur if a project results in a substantial alteration of drainage patterns that would result in a substantial increase in erosion or siltation during construction or operation of the project. At Phase 1 buildout, the proposed project would have a total of 245,059 square feet of impervious areas, 125,397 square feet of landscaped area, and 370,456 square feet of drainage management area (DMA) divided into seven drainage sub-management areas and six bioretention areas. DMA 06 would rely on interceptor tree credits rather than a bioretention area. The bioretention areas would cover 10,051 square feet, which would exceed the 9,802 square feet of bioretention required per C.3 guidance, and the interceptor tree credits equate to 44,451 square feet of treatment area thus exceeding the required 44,100 square feet. At full buildout, the proposed project would include a total of 400,973 square feet of impervious areas, 234,380 square feet of landscaped area, and 635,353 square feet of drainage management area divided into eight drainage management areas and eight bioretention areas. The bioretention areas would cover 18,657 square feet, which would exceed the 16,039 square feet of bioretention required per C.3 guidance. As previously discussed in this section, the proposed project would comply with the C.3 Permit and the SWPPP, and would implement BMPs to reduce runoff and pollution; these measures would also prevent erosion and siltation. Furthermore, as discussed in Section 2.7, Geology and Soils, the proposed project would be required to comply with the current CBC and with City Municipal Code requirements pertaining to grading and excavation in effect at the time of project approval. The proposed project would also be required to comply with the policies in the Public Safety Element of the General Plan designed to minimize the risk of soil erosion and further mitigate its effects, including Goal 1 Policy 2, which requires implementation of soils engineering and construction standards.71 With implementation of the SWPPP and BMPs and compliance with the General Plan Safety Element, the proposed project would not alter the drainage patterns such that substantial erosion or siltation would occur. Impacts would be less than significant. (ii) substantially increase the rate or amount of surface runoff in a manner which would result in flooding on- or off-site; Less than significant impact. The proposed project would install an on-site storm drainage system. Implementation of BMPs as previously discussed, such as efficient irrigation systems, minimization of impervious areas, and bioretention treatment areas, would ensure that the proposed project would not contribute to surface runoff that could result in flooding. Therefore, the proposed project would not substantially increase surface runoff on the project site. Impacts would be less than significant. 71 City of Pleasanton. 2009. Pleasanton General Plan 2005-2025, Chapter 5, Public Safety Element. Website: https://www.cityofpleasantonca.gov/civicax/filebank/blobdload.aspx?BlobID=23899. Accessed February 2, 2021.