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t <br /> rJ <br /> well casing was terminated in the vault with a waterproof <br /> locking cap, and a padlock. <br /> Development of the wells was conducted on December 29, 1987. <br /> Prior to purging, the groundwater surface elevations were <br /> determined in the existing six (6) wells and depth to water <br /> -` in MW-7 and MW-8 were determined to be 16.7 feet, and 17.2 <br /> feet respectively. All water level measurements taken to <br /> date can be found in Appendix D. MW-7 and MW-8 were purged <br /> ,x using a Tri-Lack hand pump. Prior to sampling, <br /> approximately 30 and 10 gallons of water, three (3) well <br /> volumes, were purged from wells MW--7 and MW-8, respectively. <br /> This discharge water was placed in one (1) DOT-17E 55 gallon <br /> €" drum and left on-site, pending analysis and treatment or <br /> disposal in the future. <br /> f = Groundwater samples were collected on December 24, 1987 from <br /> MW-7 and MW-8. At each of the two wells two {2) 40 ml. VOA <br /> vials with teflon caps were acidified and filled for <br /> hr benzene, toluene and xylene (BTX) testing. All samples were <br /> immediately sealed, labeled and put into cold storage for <br /> transport to the chemical laboratory. <br /> II. General subsurface and Groundwater Conditions <br /> General subsurface conditions encountered in MW-7 during <br /> drilling consisted of silty sand, road base and old asphalt <br /> at the surface. From 6 inches to 6 feet a dark brown, <br /> silty, fine grained sand was found. Beneath this sand to 8 <br /> feet a light brown silty, medium grained sand exists. Below <br /> this zone there are alternating gray silty clays and coarse <br /> to fine grained gray sands to 17 feet. From 19 to 26 feet a <br /> gray micaceous clay grading to silt was encountered. <br /> Beneath the silt a large water bearing white and black, <br /> coarse to fine, well graded, clean sand extended to 38 feet. <br /> From 38 to 50 feet a sand similar to the one above with thin <br /> alternating brown non-water bearing clays was present. <br /> Groundwater was first encountered at about 19 feet. The <br /> soil emitted a strong petroleum odor beginning at 12 feet <br /> and extended down to 26 feet. <br /> Subsurface conditions found in well MW-8 were similar to <br /> MW-7 with a thicker sand unit at the surface. Groundwater <br /> was encountered ar. about 18 feet, and the soil and <br /> groundwater in MW-8 exhibited no odor. <br />