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Page 6 January 30, 1992 Job No 400511-SA 43 Monitoring Well Surveying and Depth to Water Measurements throw MW-30 were measured relative to the to ' The elevation of the taps of casing for wells MW-27 through p of casing of monitoring well MW-11 by DERS using laser survey equipment The depth to water in the wells was measured-by DERS on-October--15,---1991 ----Ptezometric elevations were-calculated to ' determine the groundwater flow direction and gradient Depth to water measurements are summarized in Table B , 4.4 Groundwater Samphng , Groundwater samples were collected from monitoring wells MW-27 through MW-30 on October 3, , and 4, 1991 following procedures in AppendixA A slight sheen was observed on the water bailed from monitoring well MW-30 Groundwater samples were collected by DERS field personnel immediately aftcr well development was completed Appendix C contains chain-of-custody reports, and Appendix D contains field data sheets 4-5 Vapor Well Installation p Fourteen vapor extraction wells were installed on-site in clusters of two wells and one cluster of three wells Each cluster was originally planned to have one well screened in a deep zone, one well screened ' in an intermediate zone, and one well screened in a shallow zone Well construction details are presented in Table A Six deep vapor wells, VW-31, VW-32, VW-33, VW-34, VW-35, and VW-36 were installed to approximately 81 feet with 10 feet of screen The exploratory boreholes for each of these wells were logged and all soil samples were visually classified (ASTM D-2488-83) After all six deep wells were installed, an intermediate depth offset well was drilled within three feet of each deep well These six wells, VW-31-B, VW-32-B, VW-33-B, VW-34-B, VW-35-B, and VW-36-B were installed to approximately 63 feet with approximately 25 feet of screen The exact screen intervals were determined - based on the information collected from and recorded on the boring log of the deep offset well at each ' cluster well location Only two shallow vapor extraction wells were installed,VW-25-A adjacent to RW- 23 and VW-33-A adjacent to VW-33 and VW-33-B Vapor extraction well VW-25-A was installed to _39-feet with 23 feet of screen based-on the boring log fromRW-25, and VW-33-A was installed to 31 feet with 21 feet of screen based on the boring log from VW-33 Five of the shallow vapor extraction wells were eliminated because hydrocarbon odors were not detected above 40 feet in the deep offset well To confirm that no petroleum hydrocarbons were present in these 400.5111 Rev i Du Pont Environmental Remedhation Services Prtnted on Recycled Paper