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• r u CLEARWATER G R O U P [ \ C frro vurtrarntat Srrr itis Prior to purging and sampling a well, the static water level is measured to the nearest 0 01 feet with an electronic water sounder Depth to bottom is typically measured once per year, at the request of the project manager, and during Clearwater's first visit to a site If historical analytical data are not available, with which to establish a reliable order of increasing well contamination, the water sounder and tape will be decontaminated between each well If floating separate-phase hydrocarbons (SPH) are suspected or observed, SPH is collected using a clear, open-ended product bailer, and the tluckness is measured to the nearest 0 01 feet in the bailer SPH may alternatively be measured with an electronic interface probe Any monitoring well containing a measurable thickness of SPH before or during purging is not additionally purged and no sample is collected from that well Wells containing a hydrocarbon sheen are sampled unless otherwise specified by the project manager Field observations such as well integrity as well as water level measurements and floating product thicknesses are noted on the Gauging Data/Purge Calculations form Well Purziri Each monitoring well to be sampled is purged using either a PVC bailer or a submersible pump Physical parameters (pH, temperature and conductivity) of the purge water are monitored during purging activities to assess if the water sample collected is representative of the aquifer If required, parameters such as dissolved oxygen, turbidity, salinity etc are also measured Samples are considered representative if parameter stability is achieved Stability is defined as a cnange of less than 0 25 pH units, less than 10% change in conductivity i in micro mhos, and less than 1 0 degree centigrade (1 8 degrees Fahrenheit) change in temperature Parameters are measured in a discreet sample decanted from the bailer separately from the rest of the purge water Parameters are measured at least four tunes during purging, initially, and at volume intervals of one well volume Purging continues until three well casing volumes have been removed or until the well completely dewaters Wells which dewater or demonstrate a slow recharge, may be sampled after fewer than three well volumes have been removed Well purging information is recorded on the Purge Data sheet All meters used to measure parameters are calibrated daily Purge water is sealed, labeled, and stored on site in D O T-approved 55-gallon drums After being chemically profiled, the water is removed to an appropriate disposal facility by a licensed waste hauler roundwa er Sample Collection Groundwater samples are collected immediately after purging or, if purging rate exceeds well recharge rate, when the well has recharged to at least 80% of its static water level If recharge is extremely slow, the well is allowed to recharge for at least two hours, if practicable, or until sufficient volume has accumulated for sampling The well is sampled within 24 hours of purging or repurged Samples are collected using polyethylene bailers, either disposable or dedicated to the well Samples being analyzed for compounds most sensitive to volatilization are collected first Water samples are placed in appropriate laboratory-supplied containers, labeled, documented on a chain of custody form and placed on ice in a cooler for transport to a state-certified analytical laboratory Analytical detection limits match or surpass standards required by relevant local or regional guidelines CLEARWATER GROUT',INC 4 August 26, 1996