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• • p The Newark Group, Inc. (Case 2) - 2 - 30 December 2015 800 W. Church St., Stockton San Joaquin County stated DTSC records from 1993 to 2002 indicated waste as,"primarily hydrocarbons, toluene, wastewater, and ignitable related waste".. EPA records indicated use of ammonia, chlorine, dazomet (soil fumigant, pesticide), sulfuric acid, and lead. Amec Foster Wheeler could not find records of chlorinated solvent use or disposal. Amec Foster Wheeler stated chlorinated solvents have not been detected in soil or groundwater in the southwest and southeast areas of the property, Amec Foster Wheeler stated the one detection of TOE at 1.8 micrograms per Liter(ug/L) in monitoring well MW-6 was below the "California Environmental Screening Levels"AKA San Francisco Bay Regional Water Board (Region 2) ESLs and the California Maximum Contaminant Level (MCL) of 5 ug/L for drinking water. TOE and tetrachloroethene (PGE) detected near MW-6 in soil gas at 5.8 and 4.0 parts per billion by volume (ppmv) were also below the Region 2 ESLs. Amec Foster Wheeler stated there is no TOE or chlorinated solvent plume in groundwater that requires delineation. Amec Foster Wheeler stated that semi-annual groundwater monitoring would include identification of all peaks for volatile organic compounds to determine if further investigation of TOE is.justified. Our comments on this project are as follows: 1. I concur with the tasks proposed in the Work Plan with some modifications. In addition to the grab groundwater samples at 35', 45' and 55' logs, please collect grab groundwater samples at the water table (first water) at approximately 15' bgs and at 25' bgs in each of the proposed locations. Since petroleum hydrocarbons are known to float on water the highest concentrations should be observed in the upper portion of the aquifer. Please provide at least three working days notice prior to commencement of the field work so I may be present to observe this work, if possible. A report of the investigation is due 30 March 2016. 2. Although concentrations of TOE were below the MCLS in groundwater monitoring at MW-6, the fact that TOE was detected over multiple sampling events from 2014 to 2015 indicate a release has occurred. We request that by 30 March 2016 Newark either provide a list of all of the former tenants, and describe their operations and chemical used across the entire property, or provide a copy of the Phase 1 Report it prepared prior to Newark's purchase of the property. 3. Regional Water Board staff concur that continued monitoring for chlorinated solvents at detection levels comparable to Water Quality Goals is necessary, as is continued monitoring for petroleum hydrocarbons. The next semi-annual monitoring report is due 30 January 2016. 4. To date, the Electronic Data Format (EDF) uploads to GeoTracker have not been,made as required by AB 2662, By 30 January 2016 please upload all EDF data to GeoTracker for all reports and include the chlorinated solvents data with the petroleum hydrocarbons data in the EDF uploads. Submission of EDF data is required by Title 23 and Title 27 of the California Code of Regulations. 5. Please note the Central Valley Water Board staff do not use Environmental Screening Levels developed for the San Francisco Bay Regional Board. For comparison of soil and groundwater concentrations to screening levels and closure criteria, we use the State Water Board's Low Threat Closure Policy criteria in addition to Calif omia Water Quality Goals and the Office of Environmental Health Hazard Assessment's report entitled Use of California Human Health Screening Levels in Evaluation of Contaminated Properties,