COMPLIANCE INFO_PRE 2019 - Laserfiche WebLink

Home Browse Search

Well MW-23A will be used to monitor the effectiveness of the injections adjacent to the south tank farm. 7.3 Groundwater Sampling and Analysis The depth to water and total well depth will be gauged in the wells prior to purging and sampling. The wells will be purged and sampled in accordance with the low flow approach (Environmental Protection Agency [EPA], 2002). Temperature, pH, specific conductance, DO, and ORP will be measured periodically during purging and recorded on field sheets. After the parameters stabilize to within 10% of the previous value,the low-flow pump and dedicated tubing will be used to collect the sample from a discrete point within the saturated screened interval of the well into laboratory- supplied containers. The groundwater samples will be immediately labeled, sealed in a plastic bag, logged on the Chain of Custody, transferred to a cooler maintained at approximately 40Celsius, and submitted to ALS. The samples will be analyzed by the laboratory for the COCs and pilot test parameters shown on Table 3. 8.0 WELL DESTRUCTION Former extraction well E-1 and performance monitoring wells PM-1 and PM-2 will be destroyed for the following reasons: • The wells are not used for their intended purpose and provide no value in monitoring groundwater quality in the A- or B-zones. Extraction well E-1 was installed in 2001 for hydraulic testing, but was never used for groundwater remediation due to the low yield. Performance monitoring wells PM-1 and PM-2 were installed in 2006 and used for the previous pilot test, but haven't been monitored or sampled since 2008. According to the well logs, wells PM-1 and PM-2 are screened in the in fine grained soil that underlies the discontinuous water-bearing sands in the A-zone and data from these wells is not representative of the A or B zones. • Well E-1 is sampled in accordance with the MRP. However, the well is constructed with a 10-foot sump and the DTW is consistently below the bottom of the screen. The construction of the well can result in sampling stagnant water from the sump that is not representative of the A-zone groundwater. Additionally, well E-1 was not constructed according to industry standards. The well is 6-inch diameter and was installed in 8.25-inch diameter borehole. Six-inch diameter wells are typically installed in 10-inch diameter boreholes to have a sufficient amount of filter pack around the well screen. 8.1 Well Destruction Permitting Well destruction permits will be obtained from the San Joaquin County EHD. Rubik will notify the EHD and RWQCB at least 48 hours prior to the field work. CPS Stockton, California 7 D Pilot Test Work Plan A26.