Draft Environmental Impact Report - East Bay Municipal Utility District

Dingee Pressure Zone Improvement Project - Estates Reservoir Replacement ProjectWater Distribution Facilities - Initial StudyPotentiallySignificantImpactLess ThanSignificant WithMitigationIncorporatedLess ThanSignificantImpactNoImpactfor the disposal of wastewater, isthe soil capable of supporting theuse of septic tanks or alternativewastewater disposal systems?a) (i to iv). The two project sites are located in a highly active seismic area. Both reservoir sites are locatedwithin one-half mile of the Hayward Fault. The San Andreas Fault is located approximately 20 miles to theWest and the Calaveras Fault is 15 miles to the East. All existing roof structures and reservoir embankment willlikely suffer heavy damage if a major earthquake event occurs. By implementing this project, new facilitieswill be built to current industry standards that will enable the facility to better withstand damage resulting fromany such seismic event. Detailed analyses, including impacts and mitigation measures are contained in theProject Draft EIR.b) The project will not produce substantial erosion or loss of topsoil. Approximately 25 feet of the existingembankment at Estates Reservoir will be demolished and reused at the site for backfilling the two new buriedtanks. However, this material is not highly erodible; if any erosion does occur it will be contained within theexisting basin. Detailed analyses, including impacts and mitigation measures are contained in the Project DraftEIR.c) The existing embankments at Dingee and Estates reservoirs are subject to potential lateral spreading, subsidenceand localized liquefaction resulting from a nearby major earthquake on the Hayward or San Andreas Fault. Theproposed project will dewater the existing Estates reservoir and reduce the height of the Estates embankment byapproximately 25 feet . Once the replacement Estates tanks are constructed and in service, the Dingee Reservoirwill be drained and placed out of service, thereby eliminating the need to remediate the Dingee embankment.Detailed analyses, including impacts and mitigation measures are contained in the Project Draft EIR.d) The shrink-swell potential of soils at the Estates reservoir site is low and does not pose substantial risks to lifeor property.e) Municipal sewers currently serve the reservoir sites. Impacts from septic systems do not apply to this project.sb09_003.doc 17 12/10/08