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Il <br /> Newark Group - 2 - 11 July 2014 <br /> 800 West Church Street <br /> Stockton, San Joaquin Co. <br /> Well #7 could not be located. From the data provided in Table 2, Well #6 was constructed as a <br /> monitoring well and the construction details are known. <br /> My comments on the Report are as follows: <br /> 1. The low concentrations of petroleum constituents detected in the groundwater samples <br /> collected from the supply wells are possibly from the pump motors and not associated <br /> with the former tank releases on the property. Additional purging of the two wells in <br /> which the petroleum constituents were detected would not provide any apparent benefit <br /> to water quality at this Site, and may result in drawing pollutants into deeper <br /> groundwater. Given the level of uncertainty of the construction of these wells and the <br /> suspect water quality data, I believe all.five wells should be properly destroyed as soon <br /> as possible to reduce any potential human health risk, and risk of cross contamination <br /> due to vertical migration of groundwater in the wells. The San Joaquin County <br /> Environmental Health Department (SJCEHD) maintains jurisdictional authority for well <br /> destruction. Therefore, you are to contact SJCEHD to obtain approval of well <br /> destruction methodology, and all applicable permits and clearances required to properly <br /> destroy the water supply wells at this Site. You must comply with all applicable SJCEHD <br /> directives. <br /> Please submit a Well Destruction Report detailing the method of destruction and a copy <br /> of the permit obtained from the SJCEHD, within 45 days of receiving permits from the <br /> County, but no later than 31 December 2014. <br /> 2. Installation and sampling of groundwater monitoring wells in the investigation areas of <br /> borings B-7, B-14 and B-15 is needed to determine the horizontal and vertical extent of <br /> groundwater impacts caused by leaks from the former underground tank systems used <br /> at this Site. A sufficient number of monitoring wells need to be installed to define the <br /> pollutants, verify concentration trends with time, and determine groundwater gradients. <br /> In the Work Plan submitted in October 2013, ten groundwater monitoring wells, with one <br /> well installed in the B-14 area to assess if hydrocarbons are present, were proposed. <br /> However, no actual locations or schedule to complete this work has been received. <br /> Therefore, by 30 August 2014, please submit a Work Plan, including a map with <br /> proposed monitoring well locations and construction details, proposing a sufficient <br /> number of wells to delineate groundwater impacts at this Site. <br /> 3. Additional efforts should be made to locate well #7 so it may be properly destroyed. <br /> Please include in the Work Plan requested above a description of additional methods <br /> that may be utilized to locate this well. Include a time schedule to complete activities <br /> identified to complete this task. <br /> Well #6 identified in Figure 4 and Table 2 of the October 2013 Work Plan, appears to <br /> have been constructed as a shallow groundwater monitoring well. Unless it is Newark's <br /> intention to use this well in its monitoring network, including collecting and analyzing <br /> groundwater samples at least annually, this well should also be properly destroyed <br /> under permit from the SJCEHD. Please indicate in the Site Assessment Work Plan due <br /> 30 August 2014 your intentions for this well. <br />