WORK PLANS - Laserfiche WebLink

Home Browse Search

Mr. Greg Vaughn Project OC42-001.23 March 10, 1995 Page 3 Decommissioning debris will be temporarily stockpiled in STTC terminal lease areas west of Stork Road. Drilling equipment will be steam cleaned to reduce potential cross- contamination and rinsate will be containerized for disposal. Task 4 Repair Monitoring Well Pair PS/WC-2s,m EMCON installed monitoring well pair PS/WC-2s.m during the phase 1 site assessment program. A-zone monitoring well PS/WC-2s is completed at 20 feet bgs and B-zone monitoring well PS/WC-2m is completed at 35 feet bgs. The well heads were damaged by heavy equipment and the wells have been inaccessible since the third quarter of 1993. The monitoring wells are included in the quarterly sampling program defined under QMP 93-807. Well replacement will provide new monitoring wells in this part of the site. This task also responds to the Regional Water Quality Control Board (RWQCB) comments in the December 1, 1994, letter requesting actions to address the well inaccessibility and resolution of the situation. A licensed drilling contractor will drill out the surface seal, filter pack, and casing to total depth of approximately I foot below the respective well completion depth using 8-inch-diameter hollow-stem auger drilling equipment. Replacement monitoring wells will be installed in the respective borings; well completion will be similar to that of the existing monitoring wells (see Attachment A). A heavy duty vault box and concrete surface pad will be constructed over each well head to reduce the potential for future damage. Cuttings and debris generated during drilling and replacement activities will be temporarily stockpiled in STTC terminal lease areas west of Stork Road. Drilling equipment will be steam cleaned to reduce potential cross-contamination and rinsate will be containerized for disposal. An EMCON field technician will develop the replacement wells using a surge block, pump, bailer, or a combination of these techniques. Each well will be developed for approximately one hour. Water generated during well development will be containerized for disposal. Monitoring wells will be sampled during the quarterly event after replacement activities are completed. Task 5 Reporting and Debris Disposal EMCON will prepare a letter report documenting the piezometer and well decommissioning activities and replacement of well pair PS/WC-2s,m. The report will include well details for the replacement wells. Cuttings generated during decommissioning activities will be sampled to determine appropriate disposal options. Samples will be analyzed for the following parameters: SAI.W:V'1(M('4ZVX'420012.3AL-94Vfa2