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Mr. Maurice Benson <br /> June 11, 2009 <br /> Page 2 <br /> Comments <br /> 1. Page 1, Section 2.1.3, fifth sentence; The draft 2008 Annual Progress Report <br /> indicates that EWCC3 has a total well screen depth of 138' below ground surface <br /> (bgs) not the 130' indicated in the work plan. This discrepancy should be <br /> corrected in the work plan for consistency and conciseness. <br /> 2. Page 2, Well Specifications, second sentence; The proposed EWCC3R well <br /> screen intervals are 110'-115' bgs and 120'-130' bgs which varies from the <br /> current EWCC3 design. Instead of a two-screen design, EWCC3 is constructed <br /> with one (1)-10' screen interval spanning 128'-138' bgs. DESJC should provide <br /> rationale in the report indicating how the 8' loss of extraction well screen depth <br /> and two-well screens spanning a total length of 15' will affect capture in this area <br /> in comparison to EWCC3. This section should also restate the fact that <br /> professional judgment will be used in interpreting the geophysical logs and <br /> setting the final well screen depths for EWCC3R. <br /> 3. Page 5, Section 5.2.1; The sentence contradicts "EWCC3R Specifications" by <br /> stating that EWCC3R will contain a 20' screen interval when section 3.1 states <br /> the replacement well design designates two (2) separate screen intervals, <br /> totaling 15' of total screen length. These discrepancies should be corrected in <br /> the work plan for consistency and conciseness. <br /> 4. Page 5, Section 5.2.2; The sentence infers the EWCC3R well screen will extend <br /> continuously from 110'-130' bgs which contradicts section 3.1 "EWCC3R <br /> Specifications" stating the extraction well is designed for a split well screen <br /> interval with one (1) screen spanning 110'-115' bgs and the other planned for <br /> 120'-130' bgs. These discrepancies in the work plan should be corrected for <br /> consistency and conciseness. <br /> Conclusion <br /> DTSC concurs with the proposed fieldwork efforts of installing the replacement <br /> extraction well for EWCC3 as this is the main well responsible for hydraulic control and <br /> remediation of the off-site Central Area TCE plume. DTSC recommends the work plan <br /> is modified by addressing the above-mentioned comments to present a consistent and <br /> accurate depiction of the planned fieldwork efforts. <br />