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E Taj Bahadod Page 5of6 July 6, 2018 the County acknowledges that at each probe location, groundwater is likely impacted by VOCs that have migrated from the base of unlined Module I. Based on this conservative, but highly likely interpretation of VOC impact, APTIM does not believe that converting four remaining shallow single probes (SG -4, -5, -7, & -9) to triple probes will yield any new information on the extent of impact from Module I. APTIM believes that the County's resources are better allocated on installation of more LFG extraction wells as discussed above. The County should consider installing three (3) to five (5) new LFG extraction wells lieu of converting four single probe to four triple probe vadose monitoring devices. As stated above, the only mechanism to remove the LFGNOC impact from the vadose zone and groundwater is to extract more LFG. The best indication that the extraction of LFG is having a positive effect on reducing the migration from Module I is the monitoring of the shallow probe at either a single or a triple completion vadose monitoring location. Knowing what we know now, additional triple completion probes really are not necessary. The vadose zone monitoring network contains a sufficient number triple completion monitoring devices to act as surrogates for the entire thickness of the vadose zone to track the effectiveness of the LFG extraction system. However, at the present time, the existing LFG destruction system (i.e., landfill gas -to - energy plant and emergency flare) cannot accept any more LFG for destruction. The landfill gas -to -energy power plant is already operating at full capacity under the existing LFG resources and the utility flare may only be operated in emergency conditions and when the plant is shut down. As you are aware, APTIM is designing a replacement 2,000 scfin enclosed flare to comply with the latest San Joaquin Valley Air Pollution Control District Rules and Regulations. As part of this design, APTIM is working closely with the Third Party Power Plant Operator (Ameresco) to develop a performance specification that will allow the new flare station and the power plant to work collectively and cooperatively to recover and utilize LFG from FSL when new wells are installed. In addition, as noted in the December 15, 2017 letter from the County to the RWQCB, this new flare is being designed with a condensate injection system, which will vaporize condensate collected from Module I and eliminate the costly management of hauling and disposing condensate off site. To expedite the new flare project, APTIM is assisting the County in preparing a Request for Equipment Quotation that will be publicly advertised via the County's public procurement websites and also distributed to several flare manufacturers for obtaining quotes. The County will seek to have equipment quotes received by August 31, 2018 and have the manufacturer selected by September 15, 2018. Following receipt of manufacturer submittals, APTIM will be able to complete the drawings package for solicitation to General Contractors for the installation of the new flare station and new wells mentioned above. Due to the lead time on flare and blower equipment, delivery and installation of the new flare is scheduled for the Spring of 2019. 2018-07-16 FH Workplan