ARCHIVED REPORTS XR0003382 - Laserfiche WebLink

Home Browse Search

r SITE CONCEPTUAL MODEL AND REMEDIAL ACTION PLAN 10 7-Eleven Store No 14117 2725 Country Club Blvd Stockton,CA .lune 20 2002 ' 60 PROPOSED REMEDIATION METHOD DPE/IB Is the proposed remediation method at the site based on rG Documentation of expanding Indigenous microbial populations ® Reductions in MTBE through presumed biodegradation ' Fate and transport modeling Indicate low likelihood of offsite plume migration O Observed pumping Influence during the DPE test indicating a radius of Influence of about 45 ' feet from the area of extraction Three additional wells to be located, as shown on Figure 2, are recommended to allow for enhanced SVE removal of oxygenate/hydrocarbon mass from the former and current tank pit areas The wells are proposed to be constructed of 2-inch diameter, schedule 40 PVC, screened from 5 to 20 feet bg Sand filter packing will occupy the annular space to one foot above the top of the screen Interval, sealed with 2 ' feet of bentonite pellets saturated in place, capped with neat cement to grade At grade, the treatment wells will be fitted with water-tight caps and boxed In locking, water-tight traffic-rated well boxes itMobile DPE is recommended Instead of full-time DPE as more cost-effective due to less capital equipment expense, no GAC changeout costs, and no NPDES permitting requirements Groundwater Is removed directly from the site for recycling at a licensed disposal facility SVE equipment Is mobile or Is not required based on exclusion of vacuum trucks from air permitting regulations ' Intrinsic biodegradation appears to be already occurring, this remediation process may not need further enhancement Further evaluation of the process is recommended to include HPC testing of all wells at the site, specific species evaluations via microcosm studies are not recommended at this time due to cost It is recommended that for the next 6 months remediation will proceed by conducting mobile DPE using ' well MW-2 and SVE using (on a rotating basis) each of the proposed new wells combined with SVE from groundwater monitoring wells MW-1, MW-3, and MW-4 Field events are scheduled to occur every 2 weeks Onsite time is scheduled to be from 8— 10 hours each field event ' Prior to remediation initiation, all applicable local permits will need to be obtained, including any permits for well installation, and all required air discharge permits ' 61 Length of Remediation After completion of the initial 6 months of operations, groundwater extraction and plume data will be evaluated to ascertain the effectiveness of the DPE/IB process at removing the majority of the dissolved hydrocarbon/oxygenate plume At that time, any required modifications to the remediation process will be evaluated and recommended r14117Scm2 doc r