Laserfiche WebLink
3.0 ENVIRONMENTAL CHECKLIST <br />1388 Bancroft Avenue Project City of San Leandro <br />Initial Study/Mitigated Negative Declaration November 2018 <br />3.0-50 <br />which would assist with groundwater recharge. Therefore, the impact would be less than significant. <br />d, e) Less Than Significant Impact. The project site is currently developed. Construction of the <br />project would not alter the course of any creek, stream or river (the closest surface water <br />feature to the site, San Leandro Creek, is approximately 700 feet away). The project site is almost entirely covered in impervious surfaces. The project would reduce the amount of impervious surface on the site by approximately 6,214 square feet, reducing the amount <br />of stormwater runoff. The project would also include detention basins to treat roof, <br />sidewalk, and driveway water runoff. Therefore, additional stormwater percolation may occur on-site and stormwater runoff volumes would incrementally decrease. As a result, <br />the project would not increase stormwater discharge or substantially alter drainage <br />patterns on the site or the surrounding area. Further, the project would not contribute runoff <br />that would exceed the capacity of the existing on- or off-site stormwater drainage systems. Therefore, impacts would be less than significant. <br />g, h) No Impact. The project site is entirely within Federal Emergency Management Agency <br />(FEMA) Flood Zone X, Areas Determined to Be Outside the 0.2 percent (500-year) Annual <br />Chance Floodplain (FEMA 2009). Because the site is outside of the 100-year FEMA-designated floodplain, the project would not place structures inside a 100-year flood <br />hazard area. There would be no impact. <br />i) Less Than Significant Impact. Levees in San Leandro are located in the southwest corner of the city, along the waterfront, as shown in Figure 4.8-5 of the General Plan EIR (San Leandro 2016b). The project site is approximately 2.65 miles from the closest levee and <br />would not be subject to inundation in the event of a levee failure. <br />The project site is in the inundation areas of two dams: Lake Chabot and Upper San Leandro Reservoir. Lake Chabot is classified as a high hazard dam because its failure could <br />result in a significant loss of life and property damage. The California Division of Safety of <br />Dams (DSOD) inspects each dam on an annual basis to ensure the dam is safe, performing <br />as intended, and is not developing problems (San Leandro 2016a). <br />EBMUD owns and operates these two reservoirs, which store runoff from local watersheds <br />for water supply. Lake Chabot was built in 1892 and impounds approximately three billion <br />gallons of water that is used for non-potable water supply, emergency water supply, <br />conservation/storage of local runoff, and recreation (San Leandro 2016a). <br />Four miles upstream is the Upper San Leandro Reservoir, which was constructed in 1977 <br />and holds more than 13 billion gallons of water. This reservoir is closed to public access, <br />except for the trail system, and is used for raw water storage. While extremely unlikely, most of San Leandro would be flooded in the event of a dam failure at either Lake Chabot or the Upper San Leandro Reservoir (San Leandro 2016a). <br />Requirements for earthquake and flood safety for the EBMUD dams are imposed by the <br />DSOD. Chabot Dam is inspected monthly by EBMUD personnel and annually by DSOD personnel. The DSOD requires that embankments under its jurisdiction are safe enough to withstand a maximum credible earthquake without an uncontrolled release of reservoir <br />water. EBMUD is currently implementing seismic strengthening upgrades to Lake Chabot <br />dam. In 2017, the DSOD assessed the Lake Chabot dam and Upper San Leandro Reservoir dam as having the highest rating of “satisfactory” (EBMUD 2017). The risk of dam failure is <br />considered extremely low (San Leandro 2016a).