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STATE OF CALIFORNIA - Environmental Prote41Agency _ • PETE WILSON Governor <br /> CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD <br /> CENTRAL VALLEY REGION <br /> 3443 Routier Road, Suite A <br /> Sacramento, CA 95827-3098 <br /> PHONE: (916) 255-3000 <br /> DOD FAX: (916) 255-3052 <br /> 6 January 1995 <br /> Mr. Jim Pinasco <br /> Department of Toxic Substances Control <br /> 10151 Croyden Way, Suite 3 <br /> Sacramento, CA 95827-2106 <br /> DRAFT WELL MONITORING LOW-FLOW SAMPLING STUDY WORK PLAN, DEFENSE <br /> DISTRIBUTION REGION WEST (DDRW) TRACY, SAN JOAQUIN COUNTY <br /> We have reviewed the Draft Well Monitoring Program Low-Flow Sampling Study Work Plan <br /> (Work Plan) for DDRW, Tracy submitted 7 November 1994. The Work Plan is well organized and <br /> well presented. We are pleased that DDRW, Tracy is proposing to install dedicated sampling <br /> equipment for the purposes of improving the Well Monitoring Program (WMP) and conducting the <br /> proposed low-flow sampling study. The use of fully dedicated equipment will provide more <br /> consistent sampling procedures which should result in more reliable data while reducing the time <br /> required, and the overall costs associated, with current purging and sampling procedures. <br /> We have two main concerns with the Work Plan. It is not clear if DDRW, Tracy proposes to <br /> install dedicated equipment in all of the ground water monitoring wells included in the WMP. We <br /> are concerned that it may be difficult to adequately compare data from wells in the WMP in the <br /> future, if the dedicated bladder pump equipment is not installed in all WMP wells. In addition, we <br /> are concerned that the objectives of the proposed low-flow sampling study may be compromised if <br /> the dedicated bladder pumps are not used to collect ground water samples both under low-flow and <br /> conventional purge methods. These concerns, and our additional commclnts, which must be <br /> addressed in a revised version of the Work Plan, are discussed in more detail below. <br /> MAIN CONCERNS <br /> 1. Dedicated Equipment. Section 2.3 of the Work Plan indicates that the bladder pumps <br /> installed as part of the low-flow study will remain permanently as dedicated purging and <br /> sampling equipment to be used in future monitoring rounds. As previously discussed, we <br /> believe that the WMP at DDRW, Tracy will benefit from the use of dedicated sampling <br /> equipment. However, based on the criteria presented in Section 3.1.0.1 of the Work Plan, it <br /> appears that the dedicated bladder pump equipment may not be suitable for all wells included <br /> in the WMP. In addition to the wells which have been proposed to be included in the Low- <br /> Flow Sampling Study, the Work Plan must identify the wells proposed for future installation <br /> of the dedicated bladder pump equipment. Figure 3-1, Figure 3-2, and Figure 3-3 should be <br /> modified to distinguish between wells proposed to be included in the low-flow study, <br /> additional wells proposed for dedicated equipment, and other illustrated wells. <br />