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Groundwater Well Installation Work Plan Sharpe Army Depot Lathrop, California Reviewer Nadia Hollan Burke organization Environmental Protection Agency Date April 4, 2023 Item Reference Review Comment Response 4. Section 3.2.1.3, The text states that the sounding pipe ends will be sealed Revised. Section 3.2.1.3 has been revised to state that the Sounding Pipe, with polyethylene wrapping and the wrapping will be pipe will not be removed from the wrapping until Page 11 removed after installation; however, it is unclear how the installation. wrapping will be removed if both ends are sealed when the pipe is placed. Please elaborate on how the wrapping will be removed or revise this section to state the wrapping will be removed prior to installation of the sounding pipe. 5. Section 3.2.2, The text states well development will be complete when Revised. Section 3.2.2 has been revised to state, "Water Well all visible sediments have been removed and groundwater will be removed from the well using a submersible pump Development, quality parameters (temperature, dissolved oxygen, until field-measured water quality parameters have Page 13 oxidation reduction potential, pH and conductivity) have stabilized, or until at least ten well volumes are removed stabilized in a reasonable amount of time and a senior (DTSC, 2014)." geologist will be consulted; however, a reasonable amount of time is not defined and it is not clear how development will be completed if the time required exceeds a reasonable amount. Please define what a reasonable amount of time is and consider including a contingency if stabilization is not met in this timeframe. 6. Section 3.2.7, The text states soil samples will be collected and logged Clarification. Proposed well locations and screen intervals Sampling, by a qualified geologist for lithology; however,the text are based on data collected from the Groundwater Page 17 does not state if soil will be evaluated for contamination Monitoring Program. Discrete soil sampling will be used for including screening with a photoionization detector(PID), logging purposes only and to select the final screen depth. which may provide additional information for well screen No edits to the text were made. placement. Please consider evaluating retrieved soil for volatile contamination. 7. Table 1, The extraction well and well construction details Revised.Table 1 was revised to reflect the correct well Specifications (estimated borehole depth, screen slot size, and screen intervals. for Proposed estimated screened interval) in Table 1 are inconsistent Groundwater with the text. For example,Table 1 indicates the Ahtna Environmental Inc. Page 2 of 6