ARCHIVED REPORTS XR0011299 - Laserfiche WebLink

Home Browse Search

gleofag.dT?chmrs Inc Page 4 Soil Groundwater Investigation Report George s Service Project No 425 2 August 5, 1997 two boreholes, samples collected from MW-8A were used for both analytical and geological evaluation, rather then collect additional samples from the new boring The well was finstalled as described above Deeper Well The deeper monitoring well was constructed using 2 0 inch diameter PVC casing with flush threads The screened intervals extended from 45 to 47 5 feet below ground surface, or about 37 to 39 5 feet below the water table. Groundwater was encountered at approximately 7 to 8 feet below grade A 93 sand filter pack surrounded and extended two feet above the 0 020 inch screened interval and was topped by a two and a half foot weighted bentomte pellet transition seal installed on top of the filter pack A surface seal was achieved by pumping a neat cement grout (augmented with <4% bentonite) via a tremie tube The well was secured with a locking watertight cap encased in flush mounted traffic rated well box On July 26, 1997, Don Light of Del Tech mobilized to the site to developed the new monitoring wells (using mechanical surging and pumping methods) until a clear stream of water was obtained On May 5, 1997, Don Light returned to the site to purge and collect groundwater samples from the three existing monitoring wells on site, the 6 new monitoring wells and three domestic wells associated with the site All development and purge water was containerized in 55 gallon DOT approved containers and stored on site until its disposition could be arranged 2.2.1 Groundwater Sampling Procedure The groundwater in the new well was sampled no sooner than 24 hours after well development The following was the procedure for the sampling of groundwater from the 10 well Before sampling was attempted the well was sounded for depth to water The wells were then purged of at least 3 well volumes of stagnant water using a submersible pump Purging continued until the temperature, conductivity, and pH of the groundwater has 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 A stainless steel bailer was used to collect each sample Care was taken to minimize sample agitation from the initial filling of the bailer to the transfer of the sample to the VOA vial and glass amber liter bottles Once the sample container was filled and capped, the bottle was then inverted, tapped, and checked for head space bubbles The sample container was then identified and labeled with a unique designation, inserted into foam holders and placed in an 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 The effectiveness of the decontamination procedure is ensured by using the following quality control measures ' o Disposable gloves were used by the technician to collect all samples and were changed with each sampling event ' o A bailer blank for the well was collected prior to sampling by filling the decontaminated stainless steel bailer with water (provided by the laboratory) and then filling a VOA vial (provided by the laboratory) using the same procedures for actual sample collection