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Mr. Brendan Kenny July 03, 2019 As part of the hydraulic assessment the extraction rates for the existing wells were determined to be limited by the capacity of the existing conveyance pipework.The capacity of the conveyance pipework to the treatment system was increased in June 2019 with an interim improvement,which has enabled increased pumping rates to be attained from the extraction wells. The optimal extraction well pumping rates were determined from the step testing results of each extraction well. The optimized extraction rates along with the understanding of the POC geology were then used to assess hydraulic capture at the POC. Figure 2 presents a cross section along the POC highlighting the most permeable lithologies from drilling logs of existing wells. The geological cross section was used to interpret the thickness of permeable horizons screened by each of the extraction wells,which is critical for interpretation of hydraulic capture along the POC, as this is an integral factor controlling the radius of capture. The hydraulic capture for each well was determined using the United States Environmental Protection Agency(USEPA 2008)capture zone evaluation guidance (results presented in Attachment 1). The assessment indicated that full groundwater capture was likely incomplete in portions of the POC. Upon review of the hydraulic testing results and drilling logs, the extraction capacity of existing extraction well EW-4 appears low as to what might be expected when compared the screened lithology and neighboring extraction well(EW-1 and EW-2)capacities. The drilling log for extraction well EW-4 indicates the presence of 30 ft of continuous permeable strata against the screen interval, similar to extraction well EW-1.Therefore, it would be expected that the extraction capacity should be similar, however the extraction capacity of EW-1 is significantly greater than EW-4. Similarly,the production capacity of EW-2 is greater than EW-4, even though the EW-2 drilling log indicates less permeable strata at that location. These observations indicate that additional extraction capacity at EW-4 could be obtained by additional development or rehabilitation of the well. Chemical assessment of groundwater collected from the extraction wells(Attachment 1)indicated that extraction wells in the western portion of the POC had detectable concentrations of VOCs while the eastern extraction wells were non-detect. The non-detect concentrations in the extraction wells along the eastern portion of the POC is potentially attributed to a hydraulic barrier created by mounding from the GWTS infiltration basin, located to the north of the eastern portion of the POC, causing localized groundwater flow back towards the landfill.Also, mounding in the eastern portion of the POC would locally decrease the hydraulic gradient and therefore increase the actual capture radius of extraction wells EW-1 and EWA meaning that the calculations based on the regional flow gradient are conservative. Therefore, additional extraction in this portion of the POC is not recommended unless rehabilitation of extraction well EW-4 is unsuccessful or analytical trends for the extraction wells indicate increasing VOC concentrations. Groundwater appears to be hydraulically directed towards the western portion of the POC before exiting the Site northwards. Complete capture of groundwater in the western portion of the POC will require additional extraction capacity as the production capacity of extraction wells EW-2 and EW-3R has been optimized and full capture is not indicated at the optimized capacity. arcadis corn Page: Forward LF GWTS Upgrade WP 07032019.docx 2/7