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CLEARWA' TER G R O U P I N C All wells will be surveyed to the north side of the top of casing for elevations ' to the nearest ±0 01 foot Elevations will be 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 nearest benchmark ' Well Develol2ment I 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 Well development 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 10 well casing volumes have been 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, then rinsed in clean water. All data collected during development will be presented on the well development data sheet Ground Water Sampling Prior to the start of work, a decontamination area will be established This Iwill be in a secured area and consist of an Alconox solution wash, a first rinse and a second rinse Any down hole equipment will be decontaminated prior to use. Prior to g ansampling ling anY well, the static water level will be P measured with an electronic water sounder or an oil/water interface probe to Ithe nearest ±0.01 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 Ibailer Any monitoring well containing detectable amounts of floating product will not be purged or sampled. Field observations such as well I integrity as well as water level measurements and floating product thicknesses will be noted on the gauging data/purge calculations form All monitoring wells to be sampled shall be purged using either a PVC bailer or a submersible pump Physical parameters (pH, temperature and conductivity) of the purge water will be monitored for stabilization during CLEARWATER GROUP,INC 3 December 16,1994 I