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1_ Soil Vapor Extraction and Air Sparge Feasibility Evaluation Work Plan University Park September 15,2004 Page 3 l 1,2-dichloroethane (1,2-DCA) and diesel range petroleum hydrocarbons, do not appear to be particularly mobile laterally at the site. Results of the investigation also indicated that a large percentage of the soil 4 and groundwater contamination could be addressed through the proposed soil over-excavation remedial alternative. Soil over-excavation was proposed, however, to meet the very rapid property development f plan anticipated for the site at that time with the full knowledge that it would be considerably more costly than some other potentially viable remedial alternatives. As development plans for the site were modified . and clarified, the potential time-frame for remediation was lengthened, allowing consideration of a less rushed, more cost-effective measure. 3.0 SVE WELL AND AS WELL INSTALLATION This section describes the proposed installation of three SVE wells and one AS well at the site. The I proposed locations for the SVE and AS wells are shown in Figure 3, Appendix A. The purpose.of the f SVE wells is to extract and reduce volatile compound concentrations in soil in the contaminant source area near the former UST location and to capture and extract hydrocarbons volatilized by the air injected into the groundwater by the AS well. The AS well is proposed to be located near the center of the source area to provide in-situ air-stripping of volatile organic compounds in the groundwater and to provide oxygen to enhance bioremediation. The SVE well spacing is designed to provide complete, overlapping f coverage over the estimated lateral extent of soil contamination and assumes a radius of influence'-(ROI) for the SVE wells of approximately 40 feet. The ROI for the AS well is estimated to be at least 30 feet. ' The actual ROI for each well will vary depending on subsurface geologic conditions. 3.1 SITE PREPARATION ,.- Condor will complete well permit applications for the installation of the AS and SVE wells and will . obtain the required permits from the SJCEHD prior to the fieldwork. Condor will schedule and coordinate ' all drilling activities through the SCSA and the SJCEHD. The proposed SVE and AS well locations will be marked with white paint and Underground Service Alert (USA) will be notified at least 72 hours in advance of the fieldwork.to locate and identify underground utilities in and near the work area. Because companies contacted by USA may not identify utilities past private property lines and into the site, however, it is the responsibility of the property owner to identify any site utilities. �. 3.2 SVE WELL DRILLING PROCEDURES Prior to commencement of fieldwork, a tailgate safety meeting will be held and a site-specific Health and Safety Plan will be discussed with, and presented to, all field personnel for their signatures. The proposed SVE wells will be installed using hollow-stem auger drilling methods. The down-hole equipment will be decontaminated between borings by steam cleaning to prevent cross-contamination. The SVE wells will be completed to a total depth of approximately 45 feet bgs. A typical SVE well construction diagram is shown in Figure 4, Appendix A. The wells will be constructed with 20 feet of 4-inch O.D., Schedule 40, flush-threaded, machine-slotted, j' PVC screen(slot size 0.020). A flush-threaded PVC bottom cap will be placed at the bottom of each well screen. Blank PVC casing will be installed above the screen to the ground surface. No glue or solvents �. will be used in the construction of the wells. A filter pack,of#3 Monterey sand will be placed!in the annular space to approximately.one foot above the screen. Approximately three feet of bentonite pellets . will be placed above the sand to form a protective seal. A seal of neat cement will be tremied into the 4 annulus from the bentonite seal to the ground surface and locking traffic boxes will be installed at the ground surface. CONDOR is 'i