Laserfiche WebLink
76 Service Station No. 11190 4'3a-? 5 October 2016 <br /> 1206 East March Lane <br /> Stockton, San Joaquin County 96 2016 <br /> the Site, all other identified wells were dibtl6ftfihed to be located at distances of greater <br /> than 2,000 feet from the Site. ATC stated that two additional wells may be located within <br /> '/2 mile of the Site, but due to limited information, the precise location of the wells could <br /> not be determined. Identified wells have not been field verified. <br /> Central Valley Water Board staff request that the well identified within 1,250 feet of the <br /> Site be field verified, and that a field reconnaissance of 1,000 feet around the Site be <br /> performed to confirm the lack of water supply wells. Staff further request that the closest <br /> surface water be identified and the distance from the Site be provided. Distance from <br /> the defined groundwater pollutant boundary to water supply wells and surface water are <br /> part of the low risk screening criteria outlined in the State Water Resources Control <br /> Board's (State Water Board's) Low Threat Closure Policy (LTCP). Please include this <br /> information in the Fourth Quarter 2016 Semi-Annual Groundwater Monitoring Report, <br /> due 31 January 2017. <br /> 4. According to the Well Report, a waste oil tank was removed from this Site in 1987. <br /> Please include in the Work Plan due 15 August 2016, the soil analytical results for all <br /> soil samples collected during removal of the waste oil tank. Soil samples from a waste <br /> oil tank must include analysis for polycyclic aromatic hydrocarbons (PAHs), <br /> polychlorinated biphenyl (PCBs), semi-volatile organic compounds (SVOCs), volatile <br /> organic compounds (VOCs), TPH-oil and grease, TPH as diesel (TPH-D), TPH-G, and <br /> metals. If the soil sample(s) from the waste oil tank removal did not include all these <br /> parameters, additional soil sampling must be conducted. Therefore, if waste oil <br /> parameters were not previously tested, please also include a scope of work in the Work <br /> Plan due 15 December 2016, for advancement and sampling of a soil boring through <br /> the former waste oil tank location and collection of soil for analysis for waste oil <br /> parameters. <br /> 5. A groundwater gradient map was not presented in the 2Q2016 Report. Calculation of <br /> groundwater flow direction and gradient is needed to understand pollutant migration. <br /> Please include a groundwater gradient map, and a rose diagram of current and historic <br /> groundwater flow directions in future reports. Inclusion of this information will allow for <br /> better understanding of long term groundwater flow direction trends, and faster staff <br /> review. <br /> 6. Groundwater data tables should include all historic groundwater monitoring results. <br /> Elevated concentrations of TBA are detected in Site wells, however historic <br /> concentrations of TBA are not presented in groundwater data table. Please include <br /> comprehensive groundwater analytical data tables in all future semi-annual groundwater <br /> monitoring reports. <br /> 7. Please include a well construction details table in all future reports. The table should <br /> include, at a minimum, well name, installation date, total depth, screen interval, filter <br /> pack interval, and well seal interval. Inclusion of this information will allow for faster <br /> review by staff. <br /> In summary, Central Valley Water Board staff expect the following: <br />