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' 16 February 1999 • AGE-NC Project No 97-0290 Page 3 of 11 3.0. PROCEDURES ' Field procedures for the collection of soil samples,completion and development of monitoring wells and performance of ground water monitoring and sampling are described below 3 1 PROBING AND SAMPLING On 12 October 1998, three soil probe borings (probings) were advanced at the site using AGE's ' Geoprobe 5400 probing unit equipped with 1 25-inch diameter probe rods and a 2 15-inch diameter soil sampling assembly Probing P1 was advanced to a depth of 15 feet below surface grade, where probing refusal was encountered Soil samples were collected at depths of 10 and 15 feet bsg Probings P2 and P3 were advanced to a vertical depth of 50 feet bsg Soil samples were collected at 5-foot intervals, beginning at a depth of 10 in probing P2 and beginning at a depth of 15 feet in probing P3 Probe boring locations are shown on Figure 2 ' All samples were collected using the Geoprobe soil sampling assembly loaded with four 1 125-inch by 6-inch brass sleeves All probing rods, sampling tools and sample liners used for sample collection were thoroughly rinsed with clean water after washing with a solution of Alconox between each sampling run After collection,the ends of the second brass sleeve were covered with aluminum sheets, capped and sealed with tape The sleeves were labeled and placed in a chilled container Following collection of soil samples, probings P2 and P3 were advanced to a depth of 60 feet bsg using a Geoprobe water sampling assembly equipped with a retractable slotted PVC screen and a grab water sample was then collected in each boring A modified bailer consisting of Teflon tubing and a check valve were inserted through the probe rods and into the screen and used to bring the samples to the surface Each grab water sample was transferred into 40-m1 VOA vials containing 0 5 ml 18% hydrochloric acid as a sample preservative The sample collected from probing P3 was also transferred into a one-liter amber bottle Grab ground water and selected soil samples were transported under chain-of-custody, to McCampbell Analytical, Inc (MAI) in Pacheco,a California Department of Health Services (DHS)- certified analytical laboratory 32 DRILLING AND SAMPLING In November and December 1998 and in January 1999,eleven soil borings were advanced at the site Borings MW 1 through MW7 and borings B4 through B7 were advanced to a depth of 60 feet bsg using a CME-75 drill rig, equipped with 7 25-inch diameter hollow-stem augers that were used to Ad anced GcoEnv iron mental,Inc