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L, 1 <br /> • 25 August 1995 <br /> AGE-NC Project No 95-0143 <br /> Page 2 of 6 <br /> Fremont Street The two plumes do not appear to have coalesced Several additional sites with <br /> possible impacted ground water are located up-gradient and cross-gradient of the site However, <br /> these sites do not appear to have impacted the subject site The PHS/EHD is requiring further <br /> investigation to define the lateral extent of impacted soil and ground water <br /> 3.0. PROCEDURES <br /> 3 1 MONITORING WELL PURGE PROCEDURES <br /> On 11 May 1995, a Sohnst water level meter was used to measure the depth to ground water in, each <br /> well relative to the top of the casing The relative ground water elevations and hydraulic gradient <br /> were determined from these data (Table 1) <br /> Monitoring wells MW-6,MW-7 and MW-9 were then purged using a 2-stage purge pump The purge <br /> pump was decontaminated between each well using an Alconox solution Approximately 10 gallons <br /> of water were removed from MW-6 and MW-7, approximately 40 gallons of water were removed <br /> from MW-9(minimum of three well volumes) Temperature, pH and conductivity were measured at <br /> two-gallon intervals(five-gallon intervals for MW-9) using an ICM model 52200 water analyzer All <br /> purged water was stored in 55-gallon drums on-site Stabilization data and field logs are included in <br /> Appendix A <br /> 3 2 COLLECTION OF GROUND WATER SAMPLES <br /> Water samples were collected from monitoring wells MW-6,MW-7 and MW-9 using new disposable <br /> bailers The samples were transferred into 40-m1 EPA vials preserved with hydrochloric acid The <br /> samples were transported in a chilled container to McCampbell Analytical Inc (MAI) in Pacheco and <br /> analyzed for total petroleum hydrocarbons as gasoline (TPH-g) and volatile orgarucs (benzene, <br /> toluene, ethylbenzene and total xylenes, BTE&X) in accordance with EPA methods 5030 and 602, <br /> respectively <br /> 33 GEOPROBE PROBINGS <br /> On 17 and 18 July 1995, 16 probings were installed at or near the site Each probing was advanced <br /> using a van-mounted Geoprobe 5400 soil probing machine equipped with 1 125-inch diameter rods <br /> All probings were backfilled to surface grade using Portland Cement The locations of the probings <br /> . are depicted in Figure 2 and Figure 3 <br />