ARCHIVED REPORTS_2010_22 - Laserfiche WebLink

Home Browse Search

Mr. Robert McClellon October 15, 2010 Page 2 Comment#3: The plan needs to be implemented in phases. The wells located in the waste should be installed first. The SVE wells should be installed only after the gas extraction wells located in the waste are deemed not adequate. Response#3: Per conversations with CalRecycle and the EHD, the SVE wells will be installed concurrently with the vertical LFG extraction wells. Forward will develop a plan to evaluate the performance of the LFG extraction wells and a corresponding procedure for the SVE operation. This plan will be provided to the EHD and CalRecycle within the next 5 days. SVE well installation will not occur until agency approval of this plan. Comment#4: The SVE wells need to be located outside the sphere influence of the perimeter monitoring points (GP12, GPI1, GPIO). A minimum distance of 300 feet shall be maintained. The SVE wells should be clustered and position to collect the landfill gas without drawing the landfill gas into the perimeter monitoring probes. The prior installation of SVE wells along the western property boundary of the "Old Forward"site was not affective in controlling the landfill gas at the boundary. The methane concentrations in the compliance monitoring probes increased greatly shortly after bringing those wells online. Response#4: Based on conversations with CalRecycle and the EHD, Forward will perform an evaluation to shift the locations of the SVE wells that will be satisfactory to both agencies and that will still be optimal for LFG migration control. Forward will supply this evaluation and new SVE well locations to CalRecycle and the EHD within 5 days. Comment#5: The plan on page 4, third paragraph states that the bentonite slurry shall be installed above the bentonite chip to approximately 2 feet below the ground surface. The remaining 2 feet will be filled with soil...The diagram on page 11 of 13 shows cement slurry for the top 2 feet. All sealing materials placed above the bentonite plug are required to be neat cement. Response#5: The Work Plan on page 4,third paragraph, states "The remaining two feet will be temporarily filled with soil..." The temporary soil layer will be installed for safety precautions so that open boreholes are not present at the site during installation. Once the wells are installed,the Work Plan states "The SVE well will be connected to a subsurface lateral, approximately 2 feet below ground surface at the well location." To clarify, when the wells are connected to the subsurface lateral, the temporary 2-foot soil layer will be removed. The well casing will be cut approximately 2 feet below grade and the SVE connections will be installed per the specifications provided in Attachment B of the Work Plan. Once connected, the upper 2 feet of each SVE well will be filled with a bentonite slurry seal to the ground surface.