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J CLEARWA"E'R G R O U P, I q C. All wells will be surveyed to the north side of the top g of casing for elevations to the nearest ±0.01 foot. Elevations will lie referenced either to mean sea level or to a project datum. A project datum is -typically chosen for its location such that it will remain unchanged in the event of site construction or other site disturbances.. Where required, the wells will be surveyed by a licensed land surveyor, relative to the neare t benchmark. . Well Development All newly installed wells will be developed prior to sampling to remove fine . grained sediments from the well and stabilize the filter pack and the disturbed aquifer materials. Welldevelopment will consist of surging .with a surge block and removing water from the well With either a pump or bailer, until-. the well is free of sediment, or after, 14 ell casing volumes have been F`y removed. Where appropriate, temperature,- pH, specific conductance and turbidity will be monitored during well development. All development equipment will be cleaned prior to use-and between wells with an Alconox solution, thenrinsed in clean water. All data collected during development. _ will be presented on the well development data sheet. I i Ground Water Sampling Prior to the start of work, a decontamination area will be established. This � will be in a secured area and consist of an Alconox solution wash, a first rinse M' } and a second rinse. Any down hole equipment will be decontaminated prior to use. j } Prior to purging and sampling any well the static water level will be measured with an electronic water sounder r an oil/water interface probe to the nearest ±0.41 foot. If floating product is detected, interface probe results will be confirmed by lowering a clear disposable polyethylene bailer down the well and measuring the product thickness to the nearest ±0.01 foot, in the bailer. . Any monitoring well containing detectable amounts of floating product will not be purged or sampled. Field observations such as well integrity as well as water level measurements and floating product thicknesses will be noted on the gauging data/purge calculations form. j All monitoring wells to be sampled shall be purged using either a PVC bailer or a 'submersible pump. Physical par meters (pH, temperature and conductivity) of the purge water-will be monitored for stabilization during 3 CLEARWA=R GROUP,INC. lune 2,1995 r-+ p