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Groundwater Well Installation Work Plan Sharpe Army Depot <br /> Lathrop, California <br />Ahtna Environmental, Inc. Page 5 of 6 <br /> <br />Reviewer Michael Darrett Organization Department of Toxic Substance Control Date July 15, 2020 <br />Item Reference Review Comment Response <br />Specific Comment <br />1. 3.2.2 Well <br />Development <br />The text states that "Water will then be removed from <br />the well using a submersible pump until field measured <br />water quality parameters (turbidity, temperature, pH, <br />and conductivity) have stabilized" However, no specific <br />values for field parameters are given for field screening. <br />DTSC and USEPA recommend using a field screening <br />turbidity of less than 5 nephelometric turbidity units{< <br />5 NTUs) for an adequately developed well 12. <br />Recommendation <br />Please revise the section to state that the wells will be <br />developed until field measured water quality <br />parameters have stabilized, and that turbidity is <br />observed below 5 NTUs. <br />Revised. The water quality stabilization parameters <br />have been added to the text. <br />2. 3.3 Waste <br />Management <br />The text states that "Piles will be covered with 20- <br />millimeter (or thicker) polyethylene plastic sheeting" <br />However, no details on the specifications of the local <br />control panels are given. This seems to be a unit error <br />and the text should be revised to state that 20 mil (0.02 <br />inches) sheeting will be used. <br />Revised. The typo have been corrected to reflect 20 mil <br />sheeting. <br /> <br />Clarification. Local control panel details are included in <br />Section 3.2.5.