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DESCRIPTION OF SITE ACTIVITIES <br /> Descriptions of site remediation and closure activities, which augment and/or replace the information <br /> given in the previous work plan, are given below. <br /> Advance Verification Borings / Install Additional Monitoring Wells <br /> In order to verify the extent of the contaminant plume, approximately ten verification borings will be <br /> advanced on the site. The drilling of verification borings will proceed from the area of known <br /> contamination outward. The outermost borings will be at locations free of contamination. If the <br /> contamination extends offsite, we will submit an addendum to this work plan describing the locations <br /> of the offsite borings, obtain access agreements from affected property owners, and acquire the <br /> necessary permits. <br /> The borings will be drilled with an six-inch hollow stem augers. Our geologist will observe the <br /> drilling procedure and will obtain soil samples at maximum depth intervals of 5 feet, at pronounced <br /> changes in soil type, at any zone of obvious contamination, and just above ground water. Soil samples <br /> will be taken for observation and organic vapor analyzer (OVA) analysis to assess the lateral extent <br /> of contamination using a 2.0 inch inside diameter split spoon sampler lined with brass tubes. The <br /> brass sample tubes will be precleaned with a trisodium phosphate solution and double rinsed with clean <br /> water. Grab ground-water samples will be taken using a clean teflon bailer. After sampling, the <br /> borings will be sealed with cement-bentonite grout. <br /> Soil and ground-water samples from the verification borings will be screened in the field for the <br /> presence of fuel constituents using the following head-space screening procedure: <br /> a. Approximately 100 mg of soil or ground water will be placed in a clean one-quart <br /> mason jar. <br /> b. The jar will be capped with aluminum foil and secured with the jar lid ring. <br /> C. After several minutes, the concentration of organic vapors in the headspace of the <br /> jar will be measured using an OVA by penetrating the aluminum foil with the OVA <br /> probe. Readings will be recorded on the boring logs. <br /> Sampling equipment will be cleaned with trisodium phosphate solution and double-rinsed with clean <br /> water between sampling events. Drilling and sampling equipment will be steam cleaned between <br /> borings. Rinse water generated by the field investigation will be stored onsite in 55-gallon drums, <br /> pending disposal. Soil cuttings will be stored onsite, on and covered by 6 mil plastic sheeting. <br /> Two of these verification borings will be developed as monitoring wells at locations northeast and west <br /> of the former tank excavation. Soil and ground-water samples from these two borings/wells will be <br /> submitted for laboratory analysis of total petroleum hydrocarbons (TPH) as gasoline using GC FID <br /> 5030, and for benzene, toluene, ethylbenzene, and xylenes (BTEX)using EPA 8020. These wells will <br /> serve to complete definition of the lateral extent of ground-water contamination. <br /> The wells will be installed to approximately 5 to 10 feet below ground water using a hollow stem <br /> auger drill rig. The wells will be constructed of 2-inch diameter, Schedule 40 PVC pipe in accordance <br /> December 15, 1994 <br /> Job No. 1278.02.01 - 2 - <br /> i <br />