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Gray Davis <br />Governor <br />California Regional Water Quality Control Board <br />Central Valley Region <br />Steven T. Butler, Chair <br />'Sacramento Main Office <br />Internet Address: http://www.swrcb.ca.govi-rwqcb5 <br />3443 Routier Road. Suite A. Sacramento. California 95827-3003 <br />Phone (91(» 255-3001) • FAX (1)16) 255-3015 CZ) <br />zz. <br />Winston H. Hickox <br />Secreany for <br />Environmental <br />Protection <br />19 June 2000 <br />Mr. Dave Olmstead <br />W.D.O., Inc. <br />23950 S. Chisman Road <br />Tracy, CA 95376 <br />CONDITIONAL APPROVAL OF GROUNDWATER MONITORING WORKPLAN, CASTELLO <br />ESTATES, TRACY, SAN JOAQUIN COUNTY <br />I have reviewed the "Workplan for Monitoring Well Installation," prepared by Holdrege & Kull, dated <br />15 June 2000. The plan was prepared in response to Regional Water Board correspondence dated <br />17 May 2000 requesting characterization of the effluent disposal area for the Castello Estates wastewater <br />treatment system. After reviewing the workplan, I have the following comments: <br />Because of the unusual size and shape of the wastewater disposal area, a fourth well is required <br />to provide adequate monitoring. The workplan states groundwater flow is to the northeast. <br />Based on that information, it is suggested that you relocate the wells as follows: move MW-1 <br />west of the wastewater disposal area, move MW-2 to an area adjacent to Lot 80, install Well <br />MW-3 in area adjacent to Lot 72, and install a fourth well (MW-4) adjacent to Lot 65. It is noted <br />that the groundwater monitoring network must monitor groundwater upgradient and <br />downgradient of the wastewater disposal area. If the well locations do not adequately monitor <br />groundwater, additional wells may be needed to monitor the wastewater disposal effect on <br />groundwater quality. <br />The goal of the groundwater monitoring program is to monitor the first saturated zone. Sampling <br />is required to determine the correct zone to monitor. Add sampling for lithologic description at <br />five-foot intervals. <br />Well development shall be performed no sooner than 24-hours after the well grout <br />(cement/bentonite slurry) has been installed in accordance with the Department of Water <br />Resources California Well Standards, Bulletin 74-90. This is considered especially important to <br />protect the surface seal of the wells. <br />If bentonite granules are used for the transition seal, hydrate and place the material with a tremie <br />pipe; if bentonite pellets are used, free fall through a dry annulus is acceptable. Because the <br />transition seal proposed is five-feet long, hydrate the seal after half the material has been placed. <br />In addition to these requirements, all requirements of the San Joaquin County Environmental <br />Health Department remain in effect. <br />California Environmental Protection AgencV <br />Recycled Paper