Laserfiche WebLink
AWES, LLC <br /> Measurement <br /> To obtain a water level measurement, lower a decontaminated electronic water level probe into the <br /> monitoring well. Care must be taken to assure that the electronic probe hangs freely in the monitoring well <br /> and is not adhering to the well casing. The electronic probe will be lowered into the well until the audible <br /> sound of the unit is detected and the light on the electronic sounder illuminates. At this time, the precise <br /> measurement should be determined by repeatedly raising and lowering the probe to obtain an exact <br /> measurement. The water level measurement is then entered on the groundwater sampling collection record <br /> sheet or field book to the nearest 0.01 feet. <br /> Decontamination <br /> The electronic probe shall be decontaminated immediately after use by wiping with isopropyl alcohol-soaked <br /> paper towels. If applicable always proceed in order from the suspected cleanest well or soil test boring to the <br /> suspected most contaminated one. <br /> Purge Volume Computation <br /> All monitoring wells will be purged prior to sample collection. Depending upon the rate of recovery,three to <br /> five volumes of groundwater present in a well or bore hole shall be withdrawn prior to sample collection. If a <br /> well or bore hole bails dry,the well or bore hole should be allowed to recharge and a sample taken as soon as <br /> there is sufficient volume for the intended analysis. The volume of water present in each well or bore hole <br /> shall be computed using the two measurable variables, length of water column in soil boring or monitoring <br /> well and diameter. <br /> Purging and Sample Collection Procedures <br /> Bailin <br /> • Obtain a laboratory decontaminated disposable bailer and a spool of nylon rope or equivalent <br /> bailer cord. Tie a bowline knot or equivalent through the bailer loop. Test the knot for adequacy <br /> by creating tension between the line and the bailer. Tie again if needed. New rope will be used <br /> for every sample or purge. New clean latex gloves will be used when touching the rope or bailer. <br /> • Spread a clean plastic sheet near the base of the well. The plastic sheet should be of sufficient <br /> size to prevent bailer or bailer rope from contacting the ground surface. <br /> • Place the bailer inside the well to verify that an adequate annulus is present between the bailer <br /> and the well casing to allow free movement of the bailer. <br /> • Lower the bailer carefully into the well casing to remove the sample from the top of the water <br /> column,taking care not to agitate the water in the well. <br /> • Pour the bailed groundwater into a bucket. Once the bucket is full,transfer the water to a barrel and <br /> contain on-site. If no regulated substances are suspected the evacuated water can be poured on the <br /> ground if local regulations allow. <br />