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, Memorandum <br /> CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD • CENTRAL VALLEY REGION <br /> 3443 Routier Road Phone: (916) 361.5600 <br /> Sacramento, CA 95827.3098 ATSS 8-495-5600 <br /> TO: Antonia K. J. Vorster FROM: Gary Reents, P.E. R E C EIN/F I) <br /> Senior Engineer Area Engineer <br /> I JAN 12.'88 <br /> ,, / IS ASSuGIAIkS, ttIC <br /> 25 November 1987 /&L LA lRA CA <br /> DATE: SIGNATURE: <br /> SUBJECT: MARLEY COOLING TOWER COMPANY WORKPLANS, SAN JOAQUIN COUNTY <br /> I have reviewed two workplans submitted by Marley, Off-site Surface Soil Sampling <br /> and Ground Water Assessment Program - Phase IV, both dated 14 October 1987. Both <br /> of these workplans were briefly discussed at our meeting with Marley and the <br /> Department of Health Services on 9 October 1987. Essentially, the workplans are <br /> additions to Marley's comprehensive Workplan dated 20 April 1987 (revised) . My <br /> comments are as follows: <br /> Ground Water Assessment Program - Phase IV <br /> 1. I agree with the proposed approach of installing an initial nest of <br /> monitoring wells near CWS Well No. 20-01. However, placing the screened <br /> Intervals contiguous will make it difficult to accurately define vertical <br /> concentration contours. Although past well nests have been constructed in <br /> this manner, Marley should select screened intervals based on lithology <br /> encountered in the field while attempting to maintain consistency between <br /> well nests and vertical separation at individual nests. Additionally, unless <br /> there is rationale otherwise, a shallow zone well should also be included in <br /> the proposed nest(s) . <br /> 2. Marley may wish to consider depth sampling techniques for qualitative plume <br /> definition prior to installing well nests. <br /> 3. All drilling, well construction, sampling and snaysis techniques should be <br /> consistent with past procedures and the Regional Board' s 2 October 1987 <br /> memorandum, or submitted for review. <br /> 4. As discussed in our 9 October 1987 meeting, Marley should integrate plume <br /> definition objectives with the Risk Assessment. <br /> Off-site Surface Soil Sampling <br /> 1. Although it is Marley's prerogative, the vertical (and areal around the <br /> south yard) sample spacings appear closer than necessary for adequate defini- <br /> tion. Wider spacings would still allow reasonably accurate interpolation to <br /> delineate contamination. <br /> 2. Samples should be spaced along the entire east side of the north yard for <br /> general definition as they are along the north and west sides. No rationale <br /> was included in the workplan as to why these areas were omitted. <br /> GAR:ej <br />