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Geologcal r"hmes Inc Page 3 151 Quarter 2002 Groundwater Monitonng Report Project No 507 2 June 17,2002 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 February 2002 monitonng event a vertical gradient was calculated for the MW- ' 9/MW-109 pair The vertical gradient was negative (a downward direction) and approximately equal in magnitude to the horizontal gradient of the water table ' 1.2 Groundwater Sampling Procedure On February 26, 2002, Don Light of Del-Tech mobilized to the site to conduct groundwater ' monitoring of the site's eleven monitoring wells ' Before sampling was attempted, the wells were sounded for depth to water and then a clear disposable bailer was used to determine if floating product was present The wells were purged of at least three well volumes of stagnant water using a dedicated Waterra check-ball assembly and '/Z inch tubing Purging continued until the temperature, conductivity, and pH of the groundwater stabilized (c10% variation in three consecutive 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 a foam holder and placed into an ice chest cooled to 4°C for transport to the laboratory All non-disposable sampling equipment was decontaminated using a hot water washer and ' detergent before and between uses Disposable gloves were used by the technician to collect all samples and were changed with each sample collection ' A chain of custody document, listing all samples collected, accompanied the samples from field to laboratory, thereby providing a means to track the movement of and insure the ' integrity of the samples All water purged from each monitoring well and not used as a sample was placed in a 55 ' gallon DOT approved container These drums were properly labeled and will be stored on site until their proper disposition can be arranged Groundwater monitoring field logs are included in Appendix C 1