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31 January 2013 <br />AGE-NC Project No. 02-0926 <br />Page 18 of 21 <br />at wells near the source or "core" area of the plumes (dissolved and adsorbed). The <br />dissolved plume appears to be relatively stable, although highly concentrated. <br />MNA is not considered to be a feasible option for the site as active remediation and is <br />unlikely prevent the plume further migration downgradient. Further, active remediation will <br />remedy the elevated hydrocarbon concentrations (mostly adsorbed mass) currently <br />exposed to groundwater at the site. <br />Costs for natural attenuation are generally lower than most active remediation options; <br />however, costs can be highly variable depending on the duration and type of monitoring <br />required. Fate and Transport modeling and a sensitive receptor survey may be used to <br />demonstrate the potential for hydrocarbons to impact nearby groundwater receptors. <br />Regular groundwater monitoring may also be used to demonstrate a stable or declining <br />groundwater plume. <br />10.0. FINAL REMEDIATION PLAN <br />Based upon petroleum hydrocarbon distribution patterns and migration pathways identified <br />in the site conceptual model, AGE recommends that the on-site air-sparging and soil vapor <br />extraction systems be utilized to remediate the remaining hydrocarbon impact to drowned <br />soils and shallow zone dissolved hydrocarbon impact at the site. Utilizing these <br />recommendations, AGE has developed a final remediation plan (FRP) for the site. <br />Remediation implementation activities will consist of the following tasks: <br />Permitting and pre-field work activities; <br />Drilling and installation of two additional air sparging wells and one vapor recovery <br />well; <br />Installation of above ground piping to remedial wells; <br />Monitoring and maintenance; <br />Preparation of reports. <br />Each of these tasks are discussed below in detail. <br />10.1. PERMITTING AND PRE-FIELD WORK ACTIVITIES <br />Applicable site boring permits will be obtained from the SJCEHD (i.e. drilling/well <br />installation permits). Currently, AGE has obtained permits from the San Joaquin Valley <br />Unified Air Pollution Control District (APCD) to operate the on-site equipment. Additionally, <br />Advanced GeoEnvironmental, Inc.