2001-06-06_GENERAL DOCUMENTS - M1974052

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CGRS, Inc. Measurement To obtain a water level measurement, lower a decontaminated electronic water level probe into the monitoring well. Care must be taken [o assure that the electronic probe hangs freely in the monitoring well and is not adhering to the well casing. The electronic probe will be lowered into the well until the audible sound of [he unit is detected and the light on [he electronic sounder illuminates. At this time, the precise measurement should be determined by repeatedly raising and lowering the probe to obtain an exact measurement. The water level measurement is then entered on the groundwater sampling collection record sheet or groundwater level data sheet to the nearest 0.01 feet. Decontamination The electronic probe shall be decontaminated immediately after use by wiping with isopropyl alcohol- soaked paper towels. Always proceed in order from the suspected cleanest well or soil test boring to [he suspected most contaminated one. Puree Volume Cornputatior: All soil test borings and temporary monitoring wells will be purged prior to sample collection. Depending upon the rate of recovery, three to five volumes of groundwater present in a well or bore hole shall be withdrawn prior to sample collection. If a well or bore hole bails dry, the well or bore hole should be allowed to recharge and a sample taken as soon as there is sufficient volume For the intended analysis. The volume of water present in each well or bore hole shall be computed using the two measurable variables, length of water column in soil boring or monitoring well and diameter. Purpin~ and Sample Collection Procedures Bailing • Obtain a laboratory decontaminated disposable bailer and a spool of nylon rope or equivalent bailer cord. Tie a bowline knot or equivalent through the bailer loop. Test the knot for adequacy by creating tension between the line and the bailer. Tie again if needed. New rope will be used for every sample or purge. New clean latex gloves will be used when touching the rope or bailer. • Spread a clean plastic sheet near the base of [he well. The plastic sheet should be of sufficient size to prevent bailer or bailer rope from contacting the ground surface. • Place the bailer inside the well to verify that an adequate annulus is present between the bailer and the well casing to allow free movement of the bailer. • Lower the bailer carefully into the well casing to remove the sample from the top of the water column, taking care not to agitate the water in the well.