WORK PLANS - Laserfiche WebLink

Home Browse Search

Work Plan for Additional Subsurface Assessment and Remedial Action—Former Unocal Station#0187 November 27,2001 in Task 6. The newly installed well will be included in the quarterly monitoring program beginning with the quarter following installation. Task 4. Sparge Point Installation The ozone microsparge well installation will be completed in conjunction with monitoring well installation. Eight K-V Associates, Inc. (KVA) microsparge well points will be installed at the locations shown on Figures 2 and 3. Drilling and sparge point installation will be performed by a California licensed driller. The two on-site well points will be installed in well borings drilled to a depth of approximately 45 feet bgs. The six off-site well points will be installed in two sets of three wells, with the wells in each set installed in well borings drilled to depths of approximately 40,65,and 110 feet bgs. Each microsparging well will consist of a 2.5 foot long, 2-inch diameter"micro-bubbling"well point screen segment set at the base of the well boring, with 3/4-inch diameter Schedule 40 PVC well casing extending from the top of the well point screen to ground surface. The annular space around each well point will be filled with Lonestar#60 sand to approximately two feet above the top of the well point,followed by a 3 to 5 foot seal of bentonite, then neat cement to ground surface. The top of each microsparging well will be protected with a flush mounted water-resistant well box set in concrete. Because these well borings are being drilled for a remediation system, no soil or grab groundwater samples will be collected from these well borings for chemical analysis. The sparge point's construction includes a check valve to prevent groundwater from entering the well casing, and therefore prevents the collection of groundwater samples from the wells. Generalized microsparging well construction details are presented in Figure 5. As part of the KVA microsparging system installation, a C-SpargeTM panel will be mounted on two posts. The panel size is approximately 31" by 39". The panel includes an ozone generator, air compressor, and a programmable timer/controller. The microsparging wells are connected to the panel by color coded, 3/8" OD LLDPE tubing. Each well will have a dedicated line. The tubing will be run through 2 or 4-inch Schedule 40 PVC conveyance piping for added protection. For the six off-site microsparging wells located on the east side of California Street (Figure 3), the tubing will run through a 4-inch diameter Schedule 40 PVC pipe buried beneath California Street. Power will be supplied by a 120-volt, 16 amp, single-phase service. The system cycles ozone/air injection between the eight microsparging wells. The schedule can be varied to match site specific conditions. The schedule will be varied as part of the system evaluation process. The projected radius of influence around each microsparge well is approximately 20 feet. Initially, the effectiveness of the system will be monitored by checking for the presence of bubbles in existing nearby monitoring wells. Existing monitoring wells surrounding the well points will continue to be monitored quarterly, and data from those wells will be used to evaluate the systems effectiveness. In addition to the current sampling parameters, the dissolved oxygen content in surrounding wells will be measured. 240042.11 5