ARCHIVED REPORTS XR0001455 - Laserfiche WebLink

Home Browse Search

• When the interface probe contacts liquid, the visual/audible alarm on the reel will be activated An oscillating alarm indicates water, a continuous alarm indicates hydrocarbon To determine the exact thickness of a hydrocarbon layer, the probe should be slowly lowered to the air/hydrocarbon interface until the alarm is activated with the probe at the exact point where the alarm comes on, read the numbers on the tape to determine the distance from the predetermined top of casing elevation mark Next, lower the probe through the hydrocarbon layer and well into the water An oscillating alarm will be obtained The probe should then be raised slowly to the hydrocarbon/water interface until the point where the alarm changes from oscillating to continuous The thickness of the hydrocarbon layer is determined by subtracting the first reading from the second reading Record the calculated value on the Well Gauging Form and Groundwater Sampling Form Groundwater Sampling Groundwater samples will be collected from selected groundwater monitoring wells to provide data which will be statistically representative of local groundwater conditions at the site Groundwater samples will be collected as follows All measuring and sampling equipment will be decontaminated prior to sample collection from each well and documented on the Groundwater Sampling Form • Prior to sampling activity, the water level of the well will be measured and the minimum • purge volume of each well will be calculated using the purge volume calculation portion of the Groundwater Sampling Form A minimum of three casing volumes will be purged prior to sample collection The actual total volume purged will be recorded on Groundwater Sampling Form • Prior to sampling, a submersible pump, centrifugal pump, peristaltic pump, or a Teflon or stainless steel bailer will be used to purge a minimum of three casing volumes from each well Purge volumes will be estimated using a flow meter or a stopwatch and a bucket to estimate flow rate, from which a time to purge the required volume will be calculated The pump will be lowered to a depth of two to three feet from bottom of the well When bailers are used for purging, the bailer should be gently lowered into the water and allowed to fill then removed Care should be taken to not agitate the water which could release volatile organics • Whenever possible, groundwater parameters (pH, temperature (in degrees Celsius [C]), specific conductance (in micromhos per centimeters squared [umbos]), and turbidity (in National Turbidity Units [NTU]) will be monitored and recorded on the Groundwater Sampling Form • If a well is purged dry before three casing volumes have been removed, the sample will be taken after the well has recovered to within 80 percent of the static water level prior to purging or after 4 hours when sufficient water volume is available to meet analytical requirements, whichever comes first Reasonable efforts will be made to avoid dewatering wells by using low-yield pumps as necessary • Water samples will be collected with a stainless steel or Teflon bailer To reduce potential cross contamination, sampling should take place in order from least to most Page 2 of 4