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AUG 10 1988 <br /> MEMORANDUM ENVIROME TAL HEALTH <br /> PERMIT/SERVICES <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: David Brent, <br /> Senior Engineer Project Engineer <br /> DATE: 5 August 1988 SIGNATURE: V _ <br /> SUBJECT: REMEDIATION PROPOSAL, UNOCAL SITE AT 5606 PACIFIC AVENUE, <br /> STOCKTON <br /> On the 25 May '1988, we received a Remediation Proposal prepared by <br /> Kaprealian Engineering Inc. (KEI) for soil and ground water remediation <br /> at the subject site. The proposal is dated 19 January 1988 . Based on <br /> the previous site investigation work done by Kleinfelder and Associates, <br /> KEI has recommended ground water remediation that neglects to consider <br /> complete plume definition and soil cleanup that will not completely <br /> eliminate the source of ground water pollution. My comments are as <br /> follows: <br /> 1. . Ground water remediation recommendations include the installation <br /> of two additional monitoring wells, sampling of all wells, and a pump <br /> test. Treatment of polluted ground water is mentioned as a possibility <br /> after the above work is completed. <br /> As with other reports submitted on behalf of Unocal this proposal does <br /> notaddress the entire Problem Assessment phase of this project. The <br /> existing monitoring wells do not completely identify the vertical and <br /> horizontal extent of the ground water pollution and as such, the Problem <br /> Assessment phase of this project is still incomplete. The two <br /> additional monitoring wells proposed in this report will not complete <br /> this phase. In our 4 March 1988 letter to Unocal we requested the <br /> Problem Assessment phase be completed (starting with a Plume Definition <br /> Workplan due 1 May 1988) and we conditionally approved interim ground <br /> water cleanup and a soil venting system. None of these tasks have beer•. <br /> completed. The plume delineation phase of this project has been <br /> requested since the outset of Regional Board involvement and never <br /> appropriately addressed by Unocal. <br /> Unocal should submit a Problem Assessment Workplan which includes a <br /> proposal and time schedule for the complete vertical and horizontal <br /> definition of the ground water pollution and will result in a complete <br /> Problem Assessment report as described in the Regional Board Reporting <br />