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• • <br /> California Regional Water Quality Control Board <br /> Central Valley Region (° <br /> Robert Schneider,Chair <br /> Winston H.Hickox Gray Davis <br /> Secretaryfor Fresno Branch Office Governor <br /> Environmental Internet Address; http://www.swrcb.ca.gov/-mgcb5 Lr�l <br /> Protection 1685 E Street,Fresno,California 93706-2020 <br /> Phone(559)445-5116•FAX(559)445-5910 <br /> FEB 1 0 2003 <br /> 7 Feb 2003 ENVIRONMENT HEALTH <br /> PERMIT/SERVICES <br /> Mr. S. Paul Verma <br /> City of Tracy <br /> 520 Tracy Blvd. <br /> Tracy, CA 95376 <br /> WESTSIDE CHANNEL OUTFALL SYSTEM (WCOS)PROJECT, DEWATERING WELL <br /> ABANDONMENT PROCEDURE, CITY OF TRACY, STANISLAUS COUNTY <br /> Construction of the WCOS stormwater project requires a dewatering system to lower the shallow <br /> groundwater table in order to proceed with excavation of the proposed pipeline route. The dewatering <br /> process involves construction of approximately 140 dewatering wells located within the right-of-way <br /> along the north side of Byron Road to just beyond (west) of the I-205 overpass and then northerly along <br /> Lammers Road. Soil and/or groundwater along much of the Byron Road portion of the route contain <br /> weathered residual petroleum hydrocarbons resulting from leaks from two Chevron/Texaco crude oil <br /> pipelines that previously existed in the area. <br /> Each dewatering well is approximately 35 feet in depth and 24" in diameter. Following well drilling, a <br /> slotted, 8" diameter, schedule 80 PVC casing is installed and backfilled with fine gravel to the surface. <br /> Approximately 130 wells have been completed, and residual petroleum constituents in soil and/or <br /> groundwater are present in a significant number of the wells. <br /> Currently, procedures for construction dewatering well abandonment are not addressed by regulation. <br /> Following project completion, an appropriate well abandonment procedure is needed to ensure <br /> protection of groundwater. Regional Board staff proposes the following procedure: <br /> 1. Remove the pumps and well casing; <br /> 2. Remove the gravel filter-pack material to at least 5-feet below existing grade; <br /> 3. Backfill with approximately 2 feet of neat cement; and, <br /> 4. After curing, backfill to the surface and regrade using clean soil compacted to an acceptable <br /> engineering specification. <br /> California Environmental Protection Agency <br /> 0 recycled Paper <br /> The energy challenge facing California is real. Every Californian needs to take immediate action to reduce energy consumpfion. For a list of simple ways <br /> you can reduce demand and cut your energy costs,see our Web-site at http://www.swob.ca.gov/mgch5 <br />