ARCHIVED REPORTS_XR0003824 - Laserfiche WebLink

Home Browse Search

GeoCagwafTechnus Inc Page 3 Groundwater Monitoring Report Project No 770 2 October 15,2002 water table between the wells The calculation considers the slope of the water table and the distance in a down-gradient direction between the two wells used in the calculations s 2B&2A Figures show ow the location of the well clusters, MW-5/105 and MW-6/-106, used ' for calculating vertical groundwater gradient in this report Table 1 includes Summary of Water Level and Gradients Water Table Wells, Table 2 includes Summary of Water Level and Gradients Deep Wells, Table 3 shows the calculated vertical gradients, and Table 6 contains the well construction details 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 June 7, 2002, monitoring event, a vertical gradient was calculated for the MW-5/- 105 & MW-6/-106 well pairs The vertical gradient was negative (a downward direction) for both wells pairs at —0 012 and —0 003 ft/ft, respectively Both positive and negative vertical gradients have been calculated for previous events Similar to the historical lateral directions, the direction of groundwater in the vertical plane also fluctuates at the site The magnitude of vertical groundwater flow direction ranges from —0 0004 to —0 0236, in a negative direction, for the last five monitoring events 1.2 Groundwater Sarnphng Procedure ' On June 7, 2002, Don Light of Del-Tech Geotechnical Support Services mobilized to the site to conduct groundwater monitoring of the site's monitoring wells ' Before sampling was attempted the wells were sounded for depth to water and then a clear p g p p ' disposable bailer was used to determine if floating product was present No free product was noted for the event however MW-4 and MW-5 contained product sheen The wells were purged of at least three well volumes of stagnant water using a dedicated Waterra ' check-ball assembly and 1/2 inch tubing Purging continued until the temperature, conductivity and pH of the groundwater stabilized (c10% variation among three readings) indicating that formation water representative of aquifer conditions was entering the wells ' 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 Once the sample container was filled and capped, the bottle was inverted, tapped and checked for headspace bubbles The sample container was identified and labeled with a unique designation, inserted into foam holders and placed into an ice chest cooled to 4°C for transport to the laboratory