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f <br /> Former UPRR Maintenance racility 2 19 February 2009 <br /> Tracy, San Joaquin County <br /> nearby HydroPunch® borings." Monitoring wells should be installed in areas that refine <br /> the concentration of total petroleum hydrocarbons quantified as diesel (TPH-d) to <br /> concentrations below 100 micrograms per liter (Ng/L). <br /> 3. The first stated objective of the investigation is to "delineate the extent of LPH [liquid <br /> petroleum hydrocarbons] to the east and west of the source area and in the vicinity of the <br /> track pan." More precisely, the objective is to delineate horizontal and vertical extent of <br /> petroleum impacts to groundwater, to non-detectable concentrations. Please ensure that <br /> the analytical laboratory achieves the detection limit (50 pg/L) to meet this objective. <br /> 4. From my review of Cleanup and Abatement Order (CAO) 92-707, the case file, and the <br /> Phase /// Bioremediation Report prepared in 1997, it is apparent that UPRR did not <br /> submit the required analyses for soil and groundwater for confirmation of the <br /> effectiveness of the biotreatment remedy in Treatment Beds 1 and 2 west of the engine <br /> house. In order to meet the Work Plan's stated objective of "assess[ing] potential <br /> impacts to groundwater from the former Toxic Pits Cleanup Act (TPCA) pond <br /> excavation," we recommend that you use the field mobilization described in the Work <br /> Plan to collect representative samples from the borings proposed for the former TPCA <br /> pond and Treatment Beds 1 and 2. Specifically, we recommend the following additions <br /> to the Work Plan: <br /> a. Direct measurements of leachability by the Waste Extraction Test using <br /> deionized water (DI-WET) for metals on representative soil samples from <br /> Treatment Beds 1 and 2. Alternately, provide written justification, supported by <br /> field data, for omitting this sampling in an Addendum to the Work Plan. <br /> b. Collection of confirmation samples for volatile organic compounds (VOCs) in <br /> Treatment Beds 1 and 2. CAO No. 92-707 called for Toxic Characteristic <br /> Leaching Procedure (TCLP) analyses for VOCs on representative soil samples <br /> from Treatment Beds 1 and 2. However, the Regional Water Board prefers <br /> analysis of soil gas samples at this time for determination of protection of human <br /> health and water quality with respect to VOCs. Collection of soil gas samples at <br /> a minimum depth of 15 feet below ground surface, from representative locations <br /> in the Treatment Beds, and analysis for VOCs, should be incorporated into this <br /> Work Plan. <br /> c. Collection of groundwater samples for analysis of total chromium, total lead, and <br /> polynuclear aromatic hydrocarbons beneath and downgradient of Treatment <br /> Beds 1 and 2. Alternately, written provide justification, supported by field data, <br /> for omitting this sampling in whole or in part in an Addendum to the Work Plan. <br /> d. Increase the number of Hydropunch borings in Treatment Beds 1 and 2 to allow <br /> for representative sampling of the above. <br /> e. ARCADIS has proposed the addition of two borings (locations to be determined) <br /> to a depth of 2 feet below ground surface in the biotreatment bed soils. Prior to <br /> completing these borings, please provide details regarding locations, how the <br /> sampling strategy meets the requirements of the CAO, and the analytical suite <br /> for these samples. <br />