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0 0 <br /> b. Expose the length of pipe with the low spot and raise the pipe to the proper <br /> elevation, eliminating the low spot. <br /> 4. Aggressively increase the LFG collection from the wells in the vicinity of the monitoring <br /> wells indicating migration. <br /> a. Increase flow rate at the flare station by 20% (accomplished September 15, 2004). <br /> b. Three days later, adjust all LFG wells to maximize collection from the wells in the <br /> vicinity of monitoring wells GW-1, -2, and 3 (accomplished September 18, 2004). <br /> c. Two weeks after the well adjustment(above), readjust the LFG wells to again <br /> increase collection from the wells in the vicinity of monitoring wells GW-1, -2, <br /> and-3. Reduce collection from any well that shows significant overdraw <br /> (accomplished October 1, 2004, LFG collection rate increased from approximately <br /> 250 to over 360 cfm). <br /> d. Continue applying aggressive vacuum, and adjust wells to provide maximum <br /> collection near any monitoring well above regulatory limits. Reduce vacuum at <br /> wells at which excessive overdraw is indicated(ongoing). <br /> ADDITIONAL MONITORING <br /> Monitor wells GW-1, -2, and -3, and the foundation vents of the structures adjacent to those wells <br /> weekly until the concentration of combustible gas at those wells is brought below regulatory <br /> limits. Take appropriate action if combustible gas is found at or above 1.25% in the foundation <br /> vents. Continue applying aggressive vacuum and adjust the LFG system monthly to maximize <br /> LFG collection from landfill adjacent to those wells. <br /> Monitor wells GW-1, -2, and-3 monthly for three months after concentration of combustible gas <br /> at wells GW-1, -2, and -3 is first brought below regulatory limits. Some variation in detections <br /> may be expected as the soil is purged of combustible gas. A short-term increase above regulatory <br /> limits is not considered an indication of renewed migration,but rather that some LFG has been <br /> trapped deeper in the soil, and is being vented by natural pressure variations as well as the LFG <br /> collection system. <br /> Monitor the LFG header on the western side of the primary site monthly for settlement that could <br /> cause low spots. This additional monitoring will be provide by: <br /> • Monitoring the elevation of the LFG header monthly. T-posts were installed along the <br /> LFG header pipe and marked to indicate an elevation that is 36" above the top of the LFG <br /> header pipe. Settlement of the landfill will cause the surface and the T-posts along the <br /> header to subside. The marks on the posts will allow the inspector to identify locations <br /> where settlement is occurring, and reset the pipe along that portion of the header. <br /> • Monitoring the vacuum along the lengths of all headers monthly. Monitoring the vacuum <br /> will be facilitated by installing six additional pressure monitoring points on the header <br /> pipe(Figure 4). Variations in the header vacuum will indicate the accumulation of <br /> Remediation Pian for LFG Migration 3 San Joaquin County Public Works/Solid Waste <br /> Hamey Lane Sanitary Landfill Revised December 14,2004 <br />