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* MEMORANDUM 0 CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD - CENTRAL VALLEY REGION 3443 Routier Road Phone: (916) 361-5600 Sacramento, CA 95827-3098 ATSS Phone: 8-495-5600 TO: Antonia Vorster FROM: John J. Tomko DATE: 17 July 1989 SIGNATURE: SUBJECT: Statement of Work for Interim Ground Water Extraction, Withdrawal , and Disposal System, July 1989, Defense Depot Tracy, San Joaquin County, I have reviewed the subject report. The Depot is requesting the telefaxing of our comments to them no later than 24 July 1989 so they can meet their funding deadline for the current federal fiscal year. The Depot has agreed to conduct a phased approach to their Interim Remedial Action as requested in our letter of May 1989. The Depot intends to install five extraction wells, three injection wells, and ten monitoring wells as an initial phase. They also intend to construct a stripping tower to handle flows up to 500 gpm. The Statement of Work provides a fairly comprehensive phased approach to the installation of an interim ground water extraction, treatment, and disposal system. However, I have the following comments and concerns regarding this Statement of Work: 1) Section 3.1 .3.4 states that a permit to discharge will have to be obtained from the Department of Water Resources and the Regional Water Quality Control Board. The only required permit to discharge to the injection wells and the storm pond is a Waste Discharge Requirement's permit from the Regional Board. A Report of Waste Discharge application form and the associated filing fee schedule must be completed by the Depot before Waste Discharge Requirements are drafted. The monitoring requirements discussed below will likely be included in the draft requirements. 2) Section 3.13. 15 discusses the content of a Ground Wates- Model Report that must be prepared by the contractor prior to the construction of the ground water system. Though the main objective of the extraction system is to contain off- site migration of contaminants, because of the unknowns associated with the hydrogeology of the site, an important aspect of this initial phase is to generate the hydrological and water quality data necessary to evaluate the effectiveness of the initial design, and to feedback the collected data, via the ground water model , to the design of the subsequent phases of extraction and injection well installation. In order to generate useful data it is necessary to install monitoring wells in the proper locations and at appropriate depths, and to effectively monitor the extraction, injection, and monitoring wells. The Ground Water Model Report should provide the strategy to be employed in collecting the necessary data. The extraction and injection wells will apparently be placed and screened within the more permeable strata underlying the site and the exact determination of these strata will be based on the field