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Groundwater Well Installation Work Plan Sharpe Army Depot <br /> Lathrop, California <br />Ahtna Environmental, Inc. Page 3 of 6 <br />Reviewer Nadia Hollan Burke Organization Environmental Protection Agency Date July 14, 2020 <br />Item Reference Review Comment Response <br />6. Section 3.2.1, Well <br />Construction, <br />Bentonite Seal, <br />Page 9 <br />The Bentonite Seal discussion should be revised to <br />clarify which bentonite seal techniques will be used <br />during installation activities. For example, the text <br />discusses unsaturated zone construction bentonite <br />hydration techniques, but the proposed wells will be <br />constructed below the water table and will be <br />hydrated by groundwater. If this is not the case, then <br />the text should clarify the scenario where bentonite <br />will be hydrated. Please revise the Bentonite Seal <br />subsection to delete or clarify why unsaturated zone <br />construction bentonite hydration techniques are <br />discussed when proposed wells will be constructed <br />below the water table. <br />Revised. Discussion of unsaturated zone construction <br />bentonite hydration techniques was removed. <br />7. Section 3.2.2, Well <br />Development, <br />Page 10: <br />Section 3.2.2 states that water will be removed from <br />the well until water quality parameters stabilize, but <br />the text does not state what values or range for each <br />parameter indicate that stabilization has occurred. <br />Additionally, the text does not specify a minimum time <br />for well development. Please revise Section 3.2.2 to <br />clarify the water quality parameter values or range <br />that indicate that stabilization has occurred. <br />Additionally, please ensure that the text specifies a <br />minimum time for well development. <br />Revised. The water quality stabilization parameters <br />have been added to the text. <br /> <br />Clarification. Well development is process- and results- <br />based. Therefore, a minimum time frame for well <br />development was not added.