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STATE OF CALIFORNIA - Environmental Protecongency • PETE WILSON Governor <br /> CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD <br /> CENTRAL VALLEY REGION cl IJII ^ 1 -I h�A' r'i <br /> 3443 Routier Road, Suite A ) <br /> Sacramento, CA 95827-3098 <br /> PHONE: (916) 255-3000 rlr �' J,� <br /> DOD FAX: (916) 255-3052 HU ' PR 2: 33 <br /> 30 August 1993 <br /> Mr. Able Haines <br /> Environmental Protection Office <br /> Bldg. S-108, Sharpe Site <br /> Defense Distribution Region West <br /> P. 0. Box 960001 <br /> Stockton, CA 95296-0710 <br /> NINETY-FIVE PERCENT REMEDIAL DESIGN REPORT AND ANALYSIS, TECHNICAL <br /> SPECIFICATIONS AND PLANS FOR CENTRAL AREA OPERABLE UNIT NO. I (OU 1), <br /> DEFENSE DISTRIBUTION REGION WEST, SHARPE, SAN JOAQUIN COUNTY <br /> We have reviewed the above referenced submittals received 6 August 1993. These documents were <br /> prepared by Montgomery Watson (M-W) for the U. S. Army Corps of Engineers. Our major <br /> concerns with the 60 Percent Remedial Design (RD) have been adequately addressed. Overall the <br /> reports are thorough and contain the elements needed to proceed to the 100 percent design phase. <br /> Our primary concerns with the 95 Percent Remedial Design and Analysis are discussed below. <br /> 1. Page 2-15, Section 2.3.2.5, and Figure 2-1; This section states that a total of three <br /> monitoring wells are proposed for the percolation pond, and refers to Figure 2-1. The <br /> locations chosen for monitoring well MW-C2 and MW-C3 shown on Figure 2-1 appear to be <br /> cross gradient of the proposed pond area. Depending on the final location of the pond, at <br /> least one of the monitoring wells should be located directly down gradient of the pond area <br /> to monitor ground water quality at the point of compliance. <br /> 2. Percolation Pond; Decisions regarding appropriate action to address total petroleum <br /> hydrocarbon and metal contamination at the proposed pond site will be deferred at this time, <br /> pending receipt of the Phase II analytical data results. The analytical results are expected to <br /> be distributed in the next two weeks. <br /> 3. Bromacil Issue; We have reviewed the First Quarter 1993 Ground Water Monitoring Report <br /> for DDRW, Sharpe. Our concerns regarding bromacil, along with other specific comments, <br /> are discussed in the enclosed memorandum dated 3 August 1993. Arsenic concentrations <br /> continue to increase in monitoring well MW-407A, which also historically has had the <br /> highest bromacil concentrations. Bromacil is not, but should be, monitored on a regular <br /> basis in this well. There is a strong correlation between the dry wells and the arsenic and <br /> bromacil concentrations found in MW-407A. Monitoring of the runoff in the area of the dry <br /> wells is warranted to determine if the increase in contaminant concentrations in MW-407A <br /> are related to storm water runoff drained into these dry wells. This area of Plume 3 should <br /> be captured by the Central Area extraction system. If the increases in arsenic, bromacil or <br /> other pollutants, are related to the dry wells and storm water runoff, Sharpe will have to <br />