SITE INFORMATION AND CORRESPONDENCE_1993-2003

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30%/Draft Submittals -2- 4 May 1993 DDRW, Sharpe 30 Percent - Remedial Design Report and Analysis 1 . Page 2-2, Section 2.1.1.2; This section refers to Figure 2-1, showing the proposed layout for the Central Area Groundwater Treatment System. Figure 2-1 is missing from this document. 2. Page 2-4, 2-5, Section 2.1.2.4; This section states that transfer pumps at the air stripper discharge will provide sufficient head for the treated groundwater to facilitate flow to the wellheads and that the injection of the water into the wells will occur through gravity flow. This section should describe what contingencies will be available should gravity flow not meet the injection performance goals. The performance of the injection pilot system must be evaluated to enhance the design of the final injection system. The Board continues to advocate the use of existing data from the injection pilot program to evaluate parameters for the final design, such as to determine whether gravity flow is adequate to meet injection rate performance goals. DDRW, Sharpe must assure that the two contracting agencies will work together to provide a thorough evaluation of the pilot system. We understand that AEC will be responsible for the construction of the injection wells. A work plan should be prepared detailing the design specifications and procedures for injection well construction. It is unclear if AEC or CoE are planning additional field tests to support the installation of the injection wells, such as pilot holes and aquifer tests. Sufficient fieldwork should be conducted to support the design of the injection wells. 3. Page 2-11, Section 2.2.4.2; This section refers to the potential use of biocides should biological growth become a problem in the injection wells, evaporation pond, or treatment system equipment. With resect to the use of biocides, there are some concerns that need clarification. The Board prefers mechanical methods over chemical treatment methods. Common biocides contain chlorine. When ambient water containing natural organic matter is chlorinated, trihalomethanes (THMs) are produced (Marshack, 1986) . Chloroform, a potential carcinogen, is one of four chemicals that are THMs. The appropriate water quality goal for application to the protection of an ambient source of domestic water supply from chloroform is the 10-` cancer risk level of 6.0 parts per billion (ppb) . The Board will not support use of a post stripping tower continuous feed chlorine injection program, unless DDRW, Sharpe can conclusively show that degradation of the groundwater will not occur. 30 Percent - Technical Specifications No Comments. 30 Percent - Plans No Comments.