ARCHIVED REPORTS XR0011092 - Laserfiche WebLink

Home Browse Search

i G¢ologua[Tecfinicsln� Page 3 Groundwater Monitoring Report Project No. 750.2 December 20,200I �- Figure 2 shows the location of the well cluster used for calculating vertical groundwater gradient in this report, MW-1 and MW-101. Table 1 shows a Summary of Water Level and Gradients Slope and Bearing and Table 3 shows the calculated vertical gradients. The information used in the calculations is shown below. Vertical gradient calculation formulas are as follows: • vertical correction for gradient: [(gw gradient slope) x (distance) = vertical correction] • vertical head: [(head of deep well) - (head of shallow+ correction) = vertical head] • vertical gradient: [(vertical head)/(vertical distance) = vertical gradient] For the November 16, 2001 groundwater measurement, the vertical gradient was calculated for the MW-I/MW-101 pair. The vertical gradient was negative (a downward direction) +- and approximately two times greater than the water table horizontal gradient. 1.2 Groundwater Sampling Procedure On November 16, 2001, Don Light of Del-Tech mobilized to the site to conduct a groundwater monitoring event. The wells were first sounded for depth to water and then they were purged of at least three well volumes of stagnant water using a dedicated Waterra pump. Purging continued until the temperature, conductivity, and pH of the groundwater stabilized (<10% variation between three readings) indicating that formation water representative of aquifer conditions was entering the well. These water quality parameters were measured at intervals of each well volume purged. Once purging was complete, a water sample was collected from the Waterra tube. Care was taken to minimize sample agitation from the initial filling of the bailer to the transfer of the +-• sample to the VOA vials. Once the sample containers were filled and capped, the bottles were inverted, tapped, and checked for headspace bubbles. Each sample container was identified and labeled with a unique designation, inserted into foam holders and placed in an 'r ice chest cooled to 4°C for transport to the laboratory. All non-disposable sampling equipment was decontaminated using a steam cleaner before and between uses. Disposable gloves were used by the technician to collect all samples and were changed with each sampling event. A chain of custody document, listing all samples collected, accompanied the samples from field to laboratory, thereby providing a means to track their movement and ensure their integrity. The purge water was placed in a 55 gallon DOT approved container, properly labeled and stored on site until its proper disposition can be arranged. Groundwater monitoring field logs are included in Appendix C.