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Dolly Madison/Langendorf Bakery - 2 - 4 April 2008 1426 S. Lir coin St., Stockto` The HHRH incorporated the data reported in the PIER into HHRH sections of data evaluation, exposure assessment, toxicity assessment, risk assessment, conclusions, and recommendations. An executive summary provides an abstract for the HHRH, concluding that cancer risk is equal to or below the 10-6 (one in one million) range that is generally acceptable. Likewise the total non-cancer risk is below the hazard index of 1 that is generally considered acceptable. As a result of these conclusions, a workplan was not submitted. The HHRH Section 2 Data Evaluation states "...not all of the data are appropriate for use in a quantitative risk assessment...Total petroleum hydrocarbon measurements, such as GRO (gasoline range organics, AKA total petroleum hydrocarbons as gasoline, or TPHg, represent mixtures of chemicals that, because of their highly variable composition, do not have descriptive health criteria. Therefore, the toxicity of these mixtures is best described by the aggregate toxicity of key individual chemicals of the mixture, such as BTEX(benzene, toluene, ethylbenzene, and xylenes). For the purpose of this evaluation, and as is the practice in California (Cal-EPA 1994), TPH measurements were not included directly in the data evaluation process." The HHRH states xylenes and toluene were selected as chemicals of potential concern (COPCs) for soil vapor, while groundwater and soil COPCs included BTEX, tertiary butyl alcohol, methyl tertiary butyl ether, ethyl tertiary butyl ether, tertiary amyl methyl ether and 1 ,2-dichloroethane. Comments 1. Evacuating TPHg results for soil and soil gas is the current practice in California, using the surrogate toxicity values methodology for the carbon ranges associated with gasoline, which are accepted by this office. The comparison TPHg surrogate toxicity values are available in the literature. Specifically, the San Francisco Bay Regional Water Quality Control Board's Environmental Screening Levels (ESLs), in their Screening For Env,ronmental Concerns at Sites with Contaminated Soil and Groundwater dated November 2007 (available from their website) discusses the methodology and provides references. However, the PIER states that TPHg and other constituent results detected in soil and soil gas did not exceed the ESLs Tier 1 levels. Had the TPHg exceeded the ESLs, we would have required a Tier 2 or Tier 3 Risk Assessment for TPHg, using the methodology outlined above. 2. As stated above, the proposed PIER addendum will be submitted with updated results of soil gas and groundwater monitoring from new wells in S. Lincoln St., which were delayed due to negotiations for access agreements with the City of Stockton. Note that any new soil gas results need to be compared to the November 2007 ESLs, and if they excE�ed the ESLs, a Tier 2 or Tier 3 (as appropriate) risk assessment will be required for the iew data. 3. The CAO requires that the PIER include a Workplan for additional assessment, if necessary, and a "...Problem Assessment Report (PAR) which includes information from the ,mplementation of the Workplan and sufficient detail on the nature and extent of the discharges of waste to provide a basis for future decisions regarding subsequent cleanup and abatement actions." not an addendum to PIER. As stated above, the required schedule was not included in the PIER for implementation of the Workplan. Per the