Reso 2011-192 - Laserfiche WebLink

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POTENTIALLY POTENTIALLY SIGNIFICANT LESS THAN NO ISSUES SIGNIFICANT UNLESS SIGNIFICANT IMPACT SOURCES ISSUES MITIGATION IMPACT INCORPORATED Hydrology/Water Quality (Continued) The majority of water supplies serving the City of San Leandro are obtained from the East Bay Municipal Utilities District ( EBMUD). The proposed project would not include development of any groundwater supply wells and would rely on EBMUD water supplies. About 90 percent of EBMUD water supplies are surface water resources from the Mokelumne River system with the rest from runoff from local watersheds to terminal reservoirs, such as Lake Chabot ( EBMUD 2005). With implementation of the proposed project, there would be a replacement of one type of land use (commercial office) with another type of land use (residential development). Intensity of development would be similar to existing conditions, resulting in no net change in groundwater recharge potential. As there would be no long -term impact of the project on the local groundwater table and as water supplies would not involve local groundwater resources, there are no new wells proposed. Local groundwater table impacts would be less than significant. c -f) The site is currently flat and covered by a two -story 43,200 square foot commercial office building with an associated rainfall flows over the surface to the adjacent street where it enters an existing storm drain system with an ultimate discharge into the San Francisco Bay. The proposed project includes impervious surfaces that will increase the rate and amount of runoff from the site. Mitigation measures #19 and #21 will ensure that the project will not exceed the capacity of the storm drain system or result in flooding and that run off from the site is not a substantial source of pollution or silt. Mitigation Measure # 21: Applicant shall be required to demonstrate adequacy of the existing storm drain system to handle existing run -off from the drainage basin as well as run -off from the project, upgrade the storm drain system to handle existing run -off from the drainage basin as well as run -off from the project, or meter run -off from the site so that it leaves the site at the same rate as it currently does. Mitigation Measure #22: To reduce imperviousness, the applicant shall minimize use of concrete walks and handscape areas. Planters and landscape areas shall be maximized and bioswales, paver blocks, decomposed granite and other alternative pavement materials will be utilized to promote groundwater recharge. g -h) The property is not identified as being located within a Federal Emergency Management Agency (FEMA) 100 -year floodplain. Therefore, there would be no impacts of or to the 100 -year floodplain. i) In the case of upset conditions, portions of San Leandro may be subject to flooding as a result of the failure of the Lake Chabot dam. When a dam fails, a large quantity of water flows downstream. Construction flood protection precautions are necessary where damages may originate with floods. Therefore, impacts are potentially significant and mitigation is required. Mitigation Measure #23: The applicant shall comply with the applicable City of San Leandro Engineering and Building standards as part of the entitlement process to ensure that new construction is designed to minimize the potential for damage from flooding. D Tsunamis are large sea waves generated by submarine earthquakes or similar large- scale, short - duration phenomena, such as volcanic eruptions, that can cause considerable damage to low -lying coastal areas. Because the project is located approximately 50 feet above mean sea level (AMSL), not along an exterior coast, and over one mile inland from San Francisco Bay, it would not be subject to tsunami inundation. Therefore, no impact would result, and no further analysis is required. Seiches are waves caused by large - scale, short- duration oscillation of confined bodies of water (such as reservoirs and lakes) during earthquakes that may damage low -lying adjacent areas, although not as severely as a tsunami. The closest enclosed body of water that could result in earthquake - induced seiche is Lake Chabot, over 6 miles upstream of the project site. Furthermore, there have never been any documented impacts from sciches at Lake Chabot. Therefore, the project site is not subject to seiche risk. There would be no impact, and no further analysis is required.. Implementation of Mitigation Measures #18 through 923 reduce potential impacts to a less than significant level. 2450 Washington Avenue Apartments 15 October 2011