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17 October 2000 - AGE-NC Project No. 98-0450 Page 2 of 7 2.3. WELL_ AND BORING COMPLETION — Vapor well pilot boring V W 3 through V W5 were drilled at a 25 degree angle from vertical and were completed to a depth of 50 feet below.sutface grade (bsg) with a ten-foot screen interval. Vapor well pilot borings VW6 tlu-ough VW8 were drilled vertically to 50 feet bsg and were completed as dual- screened vapor extraction Wells. usinp t%vo-inch diameter PVC casing with 0.020-inch slotted screen. These wells were constructed with one lower I0-foot and an upper 15-foot screen interval, from 40 to 50 feet bs�(r and 30 to 15 feet bsg, respectively. Vapor well borings V W9 through V W 10 were drilled to a total depth of approximately 50 feet bsg and was completed with a ten-foot screen interval from 40 to 50 feet bsg. Vapor "?cl l boring V W 11 was drilled to a total depth of _ approximately 40 feet bsg and was completed with a 20-foot screen interval from 20 to 40 feet bsg. Borings IAS I throuLdh IAS I 1 were corflplcted as air sparging wells using two-inch diameter PVC casing with 0.020-inch slotted screen. The IAS well pilot borings were drilled to a total depth of 55 feet bsg and were completed with a 5-foot screen interval from 50 to 55 feet bsg. '['he filter- pack (No. 2112 Lonestar sand) was installed from 49 feet to 55 feet bsg within the IAS pilot borings (IAS1 to IASI 1 ). A filter pack sand was installed from approximately 39 feet to 50 feet bsg within vapor wells VW-'). VW-4 and VW-5 and vapor wells VW-9 and V W-10. A filter pack sand was installed approximately 19 feet to 40 feet bsg within vapor well VW-11. A -2-foot bentonite Pellet plug was then installed above the filter pack in these wells and hydrated. Sand filter packs were installed from approximately 38 to 50 feet bsg and 14 to 35 feet bsg within vapor wells VW6 throu�1111 VW8. A bentonite pellet plug was installed above the lower filter pack from 38 to 35 Leet bsg and from 12 to 14 feet and was then fully hydrated with potable water. The wells were then �(Trouted above the bentonite transition seals to 2-feet within the surface with neat-portland cement. For this application, plastic. water-tight, access boxes were then installed over the wells. to allow networking between wells and access to the well heads. As-built well diagrams are depicted in Appendix A. 2.4. SOIL-VAPOR EXTRACTION SYSTEM INSTALLATION The SVE system utilized two-inch diameter, schedule 40 PVC piping installed underground from each well-head at vapor extraction wells and monitoring wells BMW-3, BMW-4 and B1\4W-5 to the y inlet of the vacuum blower: the outlet from the vacuum blower was routed through the catalytic converter. A Magnehelic vacuum gauge was attached to the inlet of the blower. The air flow was monitored using a Dwyer DS-200 flow sensor. The flow rate was determined from the pleasured differential pressure and the piping diameter using a nomograph (Appendix B). The vapor stream at the SVE inlet was monitored for the presence of organic vapor using. an OVA. Idvrasu'ed GeuF:ncirunmcntal,Inc.