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Den's Auto Repair Page 2
<br /> 308 South El Dorado Street April 1,2009
<br /> Stockton, California 95203-3404
<br /> Please note that effective 2008, the EHD is responsible for reviewing and approving bench-scale
<br /> test work plans for evaluation of the effects of injecting oxidizers into the subsurface. The Central
<br /> Valley Regional Water Quality Control Board (CVRWQCB) will evaluate the necessity to issue a
<br /> waste discharge requirement (WDR)permit, based on the bench-scale results. The EHD maintains
<br /> the same work plan objectives as CVRWQCB that include:
<br /> • Acquiring sufficient data to evaluate the potential cost effectiveness of insitu oxidation
<br /> (total cost estimate compared to other remedial methods) in addition to the technical
<br /> effectiveness of ozone remediation;
<br /> • Identifying adverse effects to water quality by ozone injection, and
<br /> • Projecting the extent of the adverse effects, if applicable, and the time required to restore
<br /> the aquifer to background levels.
<br /> In the ozone injection bench-scale pilot test, AGE proposes to collect discreet soil samples from
<br /> two soil borings (B-OZ1 and B-OZ2) illustrated in Figure 2 of the work plan. Soil will be
<br /> lithologically characterized and field-screened for volatile organic compounds using an organic
<br /> vapor meter with a photo-ionization detector. Proposed soil samples will be collected at depths of
<br /> approximately forty-five, fifty, and sixty-five feet below surface grade (bsg) from each of two soil
<br /> borings using Geoprobe technology. AGE proposes to combine the soil with groundwater collected
<br /> from impacted monitoring wells MW-IA and MW-2A. Since AGE proposes to"examine three sets -�
<br /> of soil-and-water-matrices samples", please clarify whether the three soil samples collected from
<br /> each of two borings will be combined prior to adding groundwater collected from MW-IA and
<br /> MW-2A to the soil. AGE also proposes to analyze groundwater samples collected from impacted
<br /> wells MW-lA and MW-2A for by-products detrimental to water quality.
<br /> AGE proposes to analyze three soil and two groundwater samples for the following:
<br /> • Total petroleum hydrocarbons quantified as gasoline (TPH-g); benzene, toluene, ethyl
<br /> benzene, and total xylenes (BTEX); methyl tertiary-butyl ether (MTBE); 1,2-
<br /> dichloroethane(1,2-DCA);
<br /> • Aluminum, antimony, (total) arsenic, barium, beryllium, calcium, (total) cadmium, (total)
<br /> chromium, cobalt, copper, (total) iron, (total) lead, magnesium, (total) manganese,
<br /> mercury, molybdenum, potassium, nickel, silver, sodium, (total) selenium, thallium,
<br /> tungsten, vanadium, zinc, chromium VI, chloride, fluoride, nitrate, sulfate, pH,
<br /> conductivity, soil oxygen demand, and chemical oxygen demand (COD).
<br /> In addition to the above, AGE proposes to analyze groundwater samples for oxidation-reduction
<br /> potential, alkalinity, and total dissolved solids (TDS).
<br /> In addition, AGE proposes to analyze soil samples for total organic carbon (TOC) and soil oxygen
<br /> demand.
<br /> Please clarify whether soil samples collected at forty-five, fifty, and sixty-five feet bsg from the two
<br /> borings will be composited based on discreet depth of collection prior to the soil analysis. y
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