Laserfiche WebLink
Town of Mashpee Sewer Commission <br /> t <br /> 16 Great Neck Road North <br /> Mashpee, MA 02649 <br /> disqualify the site, any recharge design would require careful analysis to ensure compliance with <br /> environmental regulations and protection of groundwater quality. <br /> Challenges of Groundwater Mounding and PFAS Plume <br /> Two primary challenges were discussed: groundwater mounding and the PFAS plume. For Popponesset <br /> Bay, the main concern is mounding, which occurs when added effluent raises groundwater levels. For <br /> Waquoit Bay, both mounding and potential PFAS contamination must be considered. It was emphasized <br /> that while these issues do not constitute a deal breaker,they present complications requiring careful <br /> modeling and field analysis to ensure that recharge operations do not disrupt existing ecosystems or <br /> groundwater flow. <br /> Explanation of Groundwater Mounding <br /> An exaggerated contour plan was presented to illustrate how groundwater levels rise when treated <br /> effluent is introduced to recharge beds. Modeled increases included two-foot, one-and-a-half foot, and <br /> one-foot elevations near the recharge beds, diminishing with distance. Officials noted that because <br /> groundwater flows naturally from north to south,the modeled increases are localized and primarily <br /> academic, but state regulations require thorough evaluation. <br /> Mounding becomes problematic if elevated groundwater intersects freshwater bodies, such as ponds or <br /> vernal pools, potentially disrupting natural wet-dry cycles and creating permanent wetlands. Regulators <br /> closely monitor this risk when reviewing recharge proposals to ensure ecological balance is maintained. <br /> Commissioners stressed the importance of precise modeling and site-specific evaluations to mitigate <br /> any potential negative impacts. <br /> State and Regional Considerations <br /> Mr. Meader noted that at the recent One Cape conference, DEP's regional director acknowledged that <br /> Cape Cod faces unique challenges due to its nearly 1,000 ponds. Since statewide policies do not always <br /> fit local conditions, DEP is considering Cape-specific exceptions to address recharge and mounding <br /> concerns more flexibly. <br /> PFAS Plume Location and State Requirements <br /> Maps were then reviewed showing the confirmed and presumed PFAS plume extending south from Joint <br /> Base Cape Cod.The currently proposed Waquoit Bay recharge site lies outside both plume zones. <br /> However, if a site within the plume were to be used,the state would require proof that the recharge <br /> process would not influence the plume's migration. Since such a requirement is vague and <br /> unprecedented, officials voiced caution but agreed that evaluating sites within the plume may still be <br /> worthwhile. Proposed site is North. <br /> Debate Over PFAS Monitoring in Effluent <br /> The discussion shifted to whether the town should proactively monitor effluent for PFAS. At present, <br /> wastewater facilities are not required to test for PFAS, and there is no established standard for <br /> allowable levels in effluent. Mr. Meader explained that voluntarily testing could expose the town to <br /> significant regulatory and financial consequences. If PFAS were detected,the state might require <br /> treatment, even without formal limits, imposing costly obligations that could jeopardize nitrogen <br /> reduction efforts. <br /> Some Commissioners argued for proactive monitoring, citing the inevitability of future PFAS standards <br /> and the environmental risks of inaction. Others countered that without clear treatment guidelines, <br />