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. surface (bgs) An aquitard consisting of silty clay approximately 3 to 4 feet thick separates the silty clayey sand A zone aquifer from the B zone aquifer that is found at approximately 21 feet bgs and is approximately 6 to 7 feet thick In newly installed wells MW9A/B this aquitard has drastically thinned 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) MW1 through MW5 are screened across both the A and B zone aquifers Sometime after February 1996 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 serniconfined 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 1 through MW5 4TH QUARTER 2005 SITE ACTIVITIES GROUNDWATER PUMP AND TREATMENT SYSTEM The treatment system consists of five activated water carbon units (55 gallon drums), a aeration tank with recirculating pump positioned between carbon units #2 and #3, a temporary 22,000 gallon Baker tank with high level shut off float switch and discharge pump after carbon unit 45 and the discharge drum, positioned on a plastic drum containment platform (secondary containment) A high pressure sensor placed at the influent of the #1 carbon unit is set to turn the well pump off if pressures of 12 psi or greater are indicated A high level float switch in the aeration tank will shut off the well pump A low level fluid switch in the aeration tank shuts off the recirculating pump A high level float switch in the Baker tank shuts off the recirculating pump in the aeration tank A high level float switch and an LEL sensor positioned in the discharge drum will also shut off the well pump if the LEL reaches 10% or the high water level switch is activated The treatment system was modified on December 15, 2005 The 20,000 gallon capacity Baker Tank was removed from the system along with the high level shut off float switch that was positioned in the Baker Tank The outlet from the 45 water carbon was then connected to the discharge drum All other components of the system are still in place Currently, December 30, 2005 the pump and treatment system has been turned off, with no discharge to sewer In all cases the system will not restart until a visual inspection has been achieved and the system has been manually reset The LEL readings are continuously recorded on a 7 day chart and the discharge is noted with a water totalizing meter Site visits were conducted on a weekly basis to change out the 4 Sanchez QM 4'h 2005