SITE INFORMATION AND CORRESPONDENCE_1987-1992

Home Browse Search

,LEEDSHILL•HERKENHOFF INC " SPS-QEF logged onto a chain-of-custody form identifying the project numb�.lyl�s%mple type, container type, sample identification, sampler, and date. The sampler will be brushed and washed with distilled water between each sampling interval . All sample tube inserts and drilling equipment will be thoroughly cleaned with high-pressure, hot water prior to use to prevent potential cross- contamination between borings. The test borings will be backfilled with a sand- cement grout mixture immediately after the samples are obtained. GROUNDWATER INVESTIGATION Monitoring Well Installation Pending results from the soil vapor analysis, three monitoring wells will be placed within a radius of approximately 500 feet from existing monitoring well #4 (the only monitoring well with detectable concentrations of PCE) . Figure 1 presents LH's preliminary monitoring well locations, subject to results from the soil vapor survey. The monitoring wells will not be located within 50 feet of any sewer lateral . The wells will also have a 50-foot seal , as required by the Public Health Services, San Joaquin County. Location of the monitoring wells will be verified with the RWQCB after confirmation of groundwater direction and after the soil vapor testing is complete. The three monitoring wells will be approximately 70 feet deep and designed to monitor water levels and water quality in the upper water bearing zone. The wells will be constructed with 4-inch diameter, Schedule 40 PVC well casing with flush joint threads. Fifteen continuous feet of 0.010 inch slotted screen (#10) will be installed in each well , depending on water levels encountered during drilling. The screens cannot be placed any higher than a depth of fifty feet due to San Joaquin County Environmental Health restrictions. No glue or solvent will be used in the construction of these wells. The annulus of the well will be gravel packed to above the perforated zone using an engineered sand gravel pack, and then sealed with a one-foot bentonite pellet cap prior to placement of the 50-foot cement grout sanitary seal . Each monitoring well will be equipped with a locking cover and grouted to the surface. Locations and reference point elevations (to 0.01 feet) of the wells will be determined by surveying. A typical monitoring well design is presented on Figure 2.