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Advance <br /> GeoEnvironmental, Inc. <br /> 28 August 2002 <br /> :AGE-NC Project No. 01-0827 <br /> AUG 3 0 20OZ <br /> Mr. James B. Giottonini and Ms. Sharla Hardy <br /> City or`Stockton I-NVII ONNiENI dLALl h <br /> 425 N. El Dorado Street, Third Floor PERMIT/SERVICES <br /> Stockton, CA 95202 <br /> Subject: Interim Soil Remediation Feasibility Analysis - South UST Area <br /> FIRE STATION #2 <br /> 110 West Sonora Street, Stockton, California <br /> Dear Mr. Giottonini: <br /> At your request..Advanced GeoEnvironmental,Inc. (AGE) has prepared the following analysis of the <br /> proposed remediation technology for the above referenced site in response to the San Joaquin <br /> County -- Environmental Health Department (El1D) letter received in August 2002. AGE evaluated <br /> lour corrective action options, including excavation, in-situ bioremediation, natural attenuation, and <br /> in-situ vapor extraction (Table 1) <br /> Vadose zone soil at the site is impacted by TPH-d, TPH-mo, and low BTEX concentrations to a <br /> vertical depth of approximately 25 feet below surface grade(bsg). The impacted soil is primarily fine- <br /> grained, which would fimit enhanced bio-remediation by retarding oxygen aeration of the soil and <br /> inhibiting, the injection of bio-incoculents/nutrients, and the removal of hydrocarbons by soil vapor <br /> extraction is not recommend for the long-chain hydrocarbons associated with TPH-d and TPH-mo. <br /> Natural attenuation was also evaluated, however, no reduction of mass would occur under that <br /> remediation approach and the method may not ineet regulatory requirements. <br /> Based on the distribution and concentrations of petroleum hydrocarbons in soil, lack of significant <br /> impact to ground water, a low feasibility for bioremediation, soil vapor extraction and/or any <br /> monitored natural attenuation, AGE believes excavation is the appropriate site remediation <br /> technology with the potential to address hydrocarbon-impacted soil. Excavation would require the <br /> removal of a minor volume of overburden soil in the former line trench/burn pit area, while <br /> maximizing hydrocarbon mass removal. in addition, AGE believes that excavation would be most <br /> cost-effective. Soil remediation methods, parameters and associated costs are summarized in the <br /> attached Table 1. <br /> Currently, site improvements, including a significant driveway improvement, are being completed in <br /> the area of the former south UST dispenser lines. Delays in construction due to the discovery, <br /> excavation and disposal of soil may result in the City of Stockton incurring cost over-runs and reverse <br /> 837 Shaw Road,Siockron, California 95215 <br /> Telephone(209) 467-1006 FAX(209)467-1118 <br />