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r 1 , 0 �� • 4 April 2001 AGE-NC Project No 95-0144 Page 2 of 9 2 1 1N-SITU AIR SPARGING WELL ABANDONMENT Well abandonment activities were performed on 24 October 2000 by Mitchell Drilling Environmental of Rancho Cordova The two in-situ air sparging wells were drilled out to their total depths utilizing eight-inch diameter hollow stem augers A ratio of six gallons water for every 94-pound sack of portland cement was utilized in preparation of the grout mixture Each borehole ' was completely backfilled with a portland cement grout mixture to surface grade using trerrme pipe Backfill procedures were overseen by PHS-EHD personnel 22 PROBE BORING ACTIVITIES ' Soil probe borings 15B-11 through 1513-13 were advanced 15 November 2000 utilizing a van- mounted Geoprobe 5400 equipped with 1 125-inch diameter probe rods with an attached 2 15-inch diameter soil sampler, using "direct push" technology Soil probe boring B-10 was sampled continuously using a four-foot core barrel Soil probe borings 15B-1 1, 15B-12 and 15B-13 were advaziced to a depth of 20 feet below surface grade (bsg) Soil probe boring 15B-10 was advanced t • to a depth of 40 feet bsg Grab ground water samples were collected from each boring The locations of the soil probe borings are illustrated in Figure 2 2 2 1 Soil Sample Collection Discrete soil samples were collected at depths of 5, 10, 15 and 20 feet(bsg) from soil probe bonngs 15B-11, 1513-12 and 15B-13 Soil samples were collected using a Geoprobe soil sampling assembly loaded with four pre-cleaned 1 125-inch by 6-inch brass sleeves Soil samples were preserved by - covering both ends of the second brass sleeve with Teflon sheets, capping, and seating with tape Each preserved sample sleeve was labeled with soil probe boring location, depth, tune, date and sampler's initials During advancement of soil probe boring 15B-10, soil was collected continuously ' using a Geoprobe macro soil samphng assembly and a 4-foot acetate sleeve, beginning at 4 feet bsg and continuing to the total depth of 40 feet bsg After collection, the ends of a 6-inch portion cut from the sleeve were covered with Teflon sheets, capped and sealed with tape Each sample sleeve was labeled with soil probe boring location, depth, time, date and sampler's initials Each preserved sample was logged on a cham-of custody form, placed in a chilled container and transported to McCampbell Analytical Inc (MAI), a California Department of Health Services (DHS)-certified laboratory Selected samples were analyzed for Total petroleum hydrocarbons quantified as gasoline(TPH-g), diesel(TPH-d) and motor oil . (TPH-mo) by EPA Method 5030/8015M, A&4need GeuEnvironmental,Inc