ARCHIVED REPORTS_XR0004434 - Laserfiche WebLink

Home Browse Search

Boyett Petroleum,Manteca Third Quarter 2002 Groundwater Monitoring Report Page 3 with the disposable polyethylene bailers until at least three well-casing volumes of water were removed and measurements of the electrical conductivity, pH, and temperature of the water stabilized. The purged water from the monitoring wells were containerized in 55-gallon drums and left on site pending laboratory analytical results. Groundwater Monitoring Field Forms completed for the work are included in Appendix B. On September 26, 2002, monitoring wells MW-4 and MW-5 were dry. In addition, MW-6 contained significant sediment and was purged dry during sampling. Groundwater samples were not collected from MW-4 and MW- 5, and the groundwater sample collected from MW-6 was not submitted for laboratory analyses due to the large 1 amount of sediment in the sample. Mr. Wong was on-site to observe a portion of the field activities; as a result of the conditions associated with MW-4, MW-5, and MW-6, Mr. Wong requested these wells be redeveloped. 1 On September 27, 2002, a Condor representative was on-site to redevelop MW-4, MW-5, and MW-6. Dry sediment was encountered inside the well casing of MW-5 at a depth of 19 feet(MW-5 was reportedly installed to a depth of approximately 30 feet). Approximately 30 gallons of deionized water were poured inside the well casing of MW-5 in an effort to bring the sediment into suspension. The water and suspended sediment were subsequently evacuated by bailing. This procedure failed to significantly reduce the amount of sediment inside the well casing. The sediment removed from the well consisted of medium to coarse-grained, well-rounded, and well-sorted sand. A clean 3/4-inch PVC pipe attached to a hose was inserted into the well and potable water from a spigot at the site was introduced into the well. The '/4-inch PVC pipe was moved up and down inside the well casing and frequently became stuck at a depth of approximately 19 feet bgs. The well casing was briefly evacuated of coarse-grained sand to a depth of approximately 20 feet before filling up again with sand. Sediment was encountered inside the well casing of MW-4 at approximately 20.7 feet (MW-4 was reportedly installed to a depth of approximately 24 feet). The redevelopment procedure described above was applied to MW-4 with a similar result. The well casing was briefly evacuated of coarse-grained sand to a depth of approximately 23.5 feet before filling up again with sand to approximately 19.6 feet. All attempts to clear the ' sediment from the MW-4 and MW-5 were ineffective, as it appeared the well screens were damaged and the annular sand pack was infiltrating the wells. ' Sediment was encountered inside the well casing of MW-6 at approximately 23.8 feet. MW-6 was reportedly installed to a depth of approximately 25 feet bgs. MW-6 was purged dry by bailing. Potable water was introduced into the well and the water and suspended sediment were evacuated by bailing. The total depth measured inside the well casing was approximately 24.8 feet bgs, indicating approximately one foot of sediment was removed from inside the well casing. On September 30, 2002, a Condor representative was on site to measure the water level in monitor well MW-6 and collect a groundwater sample as part of the third quarter 2002 quarterly groundwater monitoring event.The total depth of MW-6 was measured to be 24.79 feet bgs. A groundwater sample was collected from MW-6 for laboratory analyses according to the procedures previously described. The groundwater samples obtained from monitoring wells MW-1, MW-2, MW-3, MW-6, MW-7, MW-8, and 1 MW-9 were collected by filling laboratory-supplied containers with groundwater directly from the disposable bailers. The sample containers were labeled, placed in a cooler chilled with ice, and delivered in accordance with chain-of-custody procedures to Argon Laboratories, Inc., in Ceres, California. �`a CONDOR