SITE INFORMATION AND CORRESPONDENCE

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�. 'Woe MEMORANDUM CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD - CENTRAL VALLEY REGION 3443 Routier Road Phone: (916) 361-5600 Sacramento, CA 95827-3098 ATSS: 8-495-5600 TO: Antonia K. J. Vorster� FROM: David Brent Senior Engineer Project Engineer DATE: 26 May 1988 SIGNATURE; SUBJECT: TOWER PARK MARINA GROUND WATER INVESTIGATION, SAN JOAQUIN COUNTY I have completed the review of two separate reports submitted for the subject facility. The reports are a Site Characterization_ Work Plan (SCWP) , submitted for the prospective buyer of the site, Public Storage Inc. , and a Soil Boring Investigations (SBI) report, submitted on behalf of the current owners. The work is being done to determine the level and extent of hydrocarbon contamination detected at the site. Bath parties submitted their respective reports without the knowledge of the other party's submittal. I have talked with both sides and they apparently are going to consolidate their efforts in the future. The SBI consisted of 9 boreholes which resulted in the analysis of 24 soil samples and 4 waster samples for BTX and TPH. No monitoring wells were constructed. The report findings confirm that low level, localized soil contamination and possibly ground water contamination above state action levels exist in the area of some above ground tanks and underground product lines. The boreholes were completed directly east of Little Potato Slough in a north-south direction. Due to the linear alignment of the boreholes, the areal extent of the contamination cannot be ascertained from this report. The proposed SCWP will not, as intended, define the horizontal and vertical extent of soil and ground water contamination and is essentially a duplication of the work already completed in the aforementioned SRI report. Specifically, the SCWP proposes to construct 4 boreholes/monitoring wells in essentially the same alignment as the boreholes completed as part of the SBI report. This nearly straight line arrangement of monitoring wells will not allow for accurate ground water gradient measurements to be. collected nor will it provide any new information as to the areal extent of the contamination. The construction of four boreholes and monitoring wells may not be sufficient to determine the extent of the problem and it may be necessary to construct more. Placement of additional boreholes and/or wells :should be decided when more is known about the extent of contamination and direction of the local ground water gradient.