ARCHIVED REPORTS XR0006110 - Laserfiche WebLink

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• approximately 21 feet bgs and is approxim hely 6 to 7 feet thick In newly installed wells MW9A/B this aquitard has drastically 7�,ioned to a one foot thickness The B zone aquifer consists of cleaner moderately sorted fine to coarse sand that shows graded bedding (fine to coarse with depth) Beneath the B zone aquifer is stiff clay that extends from approximately 27 feet bgs to 40 feet bgs The original five monitor wells did not encounter groundwater in the A zone aquifer when initially drilled and sampled Depth to water measurements taken between 1993 and February 1996 indicate that the A zone aquifer was dry (depth to water greater than 17 feet bgs) MW 1 through MW5 are screened across both the A and B zone aquifers Sometime after February 1995 depth to groundwater measurements indicated that groundwater was in contact with the A zone aquifer, see Table 1 The groundwater in the vicinity of the site is semiconfined Groundwater elevation at the site varies from a wet year high of 7 feet bgs (silty clay formation above the A zone) to about 22 - 23 feet bgs (B zone) during the previous drought period Groundwater flow direction in the A zone at the site has generally been to the west since December 1997 The B zone shows a similar flow direction, which would be expected due to the connection between zones at wells MW l through MW5 IST QUARTER 2005 SITE ACTIVITIES DEPTH TO WATER MEASUREMENTS Depth to water was measured at all active wells on January 14, 2004 The measurements were made from the surveyed elevation at the top of casing at each well using an electrical air/water interface probe (Table 1) No free product or product sheen was observed in any of the monitor wells Table 1 also presents the Depth to Water measurements obtained from wells located at Country Club Food and Fuel The top of casing elevations for the Country Club Food and Fuel wells were adjusted in height by 2 9 feet (the most common elevation change found between the old survey and the new survey of the Sanchez wells) Western Geo-Engineers surveyed the top of casings for temporary piezometers on February 5, 2003 using level and rod COLLECTION AND CERTIFIED ANALYSES OF GROUNDWATER SAMPLES WEGE personnel collected quarterly groundwater samples from thirteen monitor wells at the site on January 14, 2005 See Appendix A for QA/QC, details, methods, procedures, abbreviations, and acronyms used in sampling and analysis Following depth to water measurements, WEGE used a truck mounted electrical submersible (Redi Flow 2) adjustable speed pump and dedicated 5/16 inch diameter polyethylene tubing to purge each well of three volumes of water and until the water • parameters, pH, conductivity and temperature stabilized 4 Sanchez QM 1st 2005