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7 f <br /> Product thicknesses will be measured using interface probes, and/or acrylic (clear plastic) bailers. The <br /> procedures for obtaining level and thickness measurements using each instrument are: <br /> • The level of the lop of the product will be measured with an interface probe. When product <br /> is suspected but not measurable with the interface probe, a visual evaluation can be made <br /> using clear bailers.A bailer will be lowered into the water/product surface so that the top of <br /> the bailer is NOT submerged; the bailer is then removed from the well and the thickness of <br /> the product visually measured and documented on the Well Gauging Form <br /> • When the interface probe contacts liquid, the vrsuaVaudible alarm on the reel will be <br /> activated An oscillating alarm indicates water, a continuous alarm rndicales hydrocarbon'. <br /> To determine the exact thickness of a hydrocarbon layer, the probe should be slowly <br /> lowered to the air/hydrocarbon interface until the alarm is activated. With the probe at the <br /> exact point where the alarm comes on, read the numbers on the tape to determine the <br /> distance from the top of casing elevation mark Next, lower the probe through the <br /> hydrocarbon layer and well into the water An oscillating alarm will be obtained The probe <br /> should then be rased slowly to the hydrocarbon/vrater interface until the point where the <br /> alarm changes from oscillating to continuous The thickness of the hydrocarbon layer is <br /> determined by subtracting the first reading from the second reading Record the calculated <br /> value on the Well Gauging Form and Groundwater Sampling Form <br /> The process desenbed here is e;,:a-e saea is Fo11aw:he Procedures eaalresble!or}aar monrlo:»g eYu;, ri <br /> Groundwater Sampling <br /> Groundwater samples will be coll_cted frorn selected orouricwater monitoring wells to provice data vrhich will <br /> be statistically representative of local cround%vater conci`+ons at the site Groundwater samples will be <br /> collected as follov.,s <br /> • All measuring and sampling equipment will be decontaminated prior to sample collection <br /> from each well and documented on the Groundwater Sampling Form. <br /> • Prior to sampling activity, the water level in the well will be measured and the minimum <br /> purge volume of eadh well will be calculated using the purge volume calculation portion of <br /> the Groundwaler Sampling Form A minimum of three casing volumes will be purged prior <br /> to sample collection. The actual total volume purged will be recorded on Groundwater <br /> Sampling Form. <br /> • Prior to sampling, a submersible pump, centrifugal pump, peristaltic pump, or a Teflon or <br /> stainless steel bailer will be used to purge a minimum of three casing volumes from each <br /> well. Purge volumes will be estimated using a flow meter or a stopwatch and a bucket to <br /> estimate flow rale, from which a time to purge the required volume will be calculated. The <br /> pump will be lowered to a depth of two to three feet from bottom of the well. When bailers <br /> are used for purging, the bailer should be gently lowered into the water and allowed to fill, <br /> then removed. Purged water may be placed info 5-gallon buckets to determine the volume <br /> of groundwater removed. Care should be taken to not agitate the water which could release <br /> volatile organics. <br /> P•WWORMPae2of5SITEX-SOP.DOC g <br />