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Groundwater Monitorir g Work-Plan 1950[Vest Fremont Street,Stockton, California 2.2.3 Well Development The wells will be developed no sooner than 72 hours after placing the annular seal. Each well will be developed to remove fine material and increase hydraulic communication with the aquifer. The wells will be developed by hand-bailing. During development, field water-quality parameters will be measured and recorded including pH, temperature, specific conductivity, and turbidity. 2.3 GROUNDWATER MONITORING Quarterly groundwater monitoring will be conducted for the new monitoring wells for four consecutive quarters. The first sampling event will begin no sooner than 24 hours after well development. Water level will be measured prior to the groundwater sampling at each monitoring event. The groundwater elevation data will be collected to evaluate groundwater flow direction and the hydraulic gradient. Earth Tech will perform growidwater sampling in accordance with standard US EPA protocol. The wells will be purged by hand-bailing with new disposable polyethylene bailers. The field parameters of temperature,pH,and conductivity of the groundwater removed will be monitored throughout the purging. After at least three (3)well volumes are removed. purging may cease when three consecutive readings of all three parameters have stabilized to within 0.5 degree C.0.1 pH unit and i micronihos. After stabilization of the field parameters, samples will be collected from the bailer. After purging, groundwater samples will be collected by transferring the groundwater sample directly from the bailers into laboratory-supplied containers with the appropriate preservatives for the analytical test methods. Each sample container was labeled immediately after sample collection and placed in a cooler with ice for transportation,under chain-of-custody protocol The following state-certified laboratories are currently proposed to conduct the groundwater analyses: • Maxsam Analytics. Inc. (Massam)located at 50 Bathurst Drive Unit 12 in Waterloo. Ontario. Canada(Telephone number: 519-474-2575)for NDMA analyses with ultra-low detection limits. • TestAmerica Laboratories, Inc. Pleasanton(TestAnmerica)located at 1220 Quarry Lane, Pleasanton, California(Telephone number: 925-484-1919)for nickel and MTBE analyses. The method detection limits(MDLs)and RLs for the planned groundwater analyses were provided by the laboratories listed above as follows: • NDMA(Massaro)by EPA Method 607/1625 Modified: MDL=0.54 nanograms per liter(ng/L), RL=2 ng/L • Nickel, dissolved(TestAmerica)by EPA 6010B: MDL=0.3 µg/L, RL=5 µg/L • MTBE (TestAunerica) by EPA 8260B: MDL=0.126 gg/L, RL=0.5 µg/L. Project 102790 6 December 2007