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t � Mr Harlin Knoll Page 2 of 4 . measured and recorded during the purging process All downhole equipment was decontaminated prior to and between each use by washing with a solution of laboratory-grade detergent and then double-rinsing with water Groundwater samples were collected using dedicated, disposal bailers after physical parameters stabilized and water levels recovered to at least 80% of pre-purged levels The samples were decanted into 40-m1 glass vials preserved with dilute hydrochloric acid and placed in an ice chest refrigerated to a temperature of approximately 4°C The samples were transported to Argon Laboratories (FLAP #2359) under chain of custody protocol and analyzed for TPHg and BTEX utilizing EPA methods 8015M and 8020, respectively Purged groundwater and decontamination ansate were contained in labeled Department of Transportation (DOT) approved drums pending disposal Copies of field purge logs and water level measurements are included in Attachment A Groundwater Analytical Results Elevated levels of dissolved gasoline constituents were detected in the groundwater sample collected from well MW5, and relatively low levels were detected in samples collected from wells MW 1 and MW2 No gasoline constituents were detected in the samples collected from wells MW3 and MW4 Well MW5 contained TPHg at a concentration of 31,000 parts per billion (ppb), benzene at 3,400 ppb, toluene at 750 ppb, ethylbenzene at 370 ppb, and xylenes at 2,800 ppb Well MW1 contained TPHg at a concentration of 760 ppb, benzene at 12 ppb, toluene at 0 5 ppb, ethylbenzene at 49 ppb, and xylenes at 25 ppb Benzene was the only chemical of concern detected in well MW2 (2 4 ppb) No gasoline constituents were detected in the samples collected from wells MW3 and MW4 Analytical results are summarized in Table 3 Laboratory data sheets and chain of custody documentation are included in Attachment B Figure 3 presents a benzene isoconcentration map utilizing the most recent analytical results Attachment C contains graphical representations of TPHg and benzene concentrations over time in site wells STATUS OF INSTALLATION OF DOWNGRADIENT WELL EHD previously requested the installation of a replacement well for recently destroyed well MW8 to continue monitoring groundwater quality downgradient of well MW5 A work plan dated August 23, 2002 was approved by EHD However, the owners of the property directly across Thornton Road from the subject site denied our request to install the replacement well on their property A copy of the access request and a parcel map are included in Attachment D i EVALUATION OF OZONE INJECTION In accordance with correspondence from EHD dated November 7, 2001, Ground Zero evaluated the feasibility of in-situ ozone injection as a remediation alternative at the site Ground Zero reviewed • specific files at the offices of EHD that documented the use and testing of ozone infection at sites G\Data\GROUNDZE\KNOWLES"AM\REPORTS\QMR13QM2002 doc