Effluent Recharge to Groundwater and Wastewater Planning – Finding Acceptable Recharge Sites

Multiple regulatory and environmental issues drive the selection of groundwater recharge sites for disposal of treated wastewater effluent on Cape Cod including nutrient loading limitations to stressed harbors and embayments, drinking water protection (Zone II Areas) and land availability. This presentation will look at site selection and groundwater modeling conducted as part of the CWMP for the Towns of Harwich and Yarmouth, Massachusetts and the challenges of identifying sites for groundwater recharge in a Cape Cod. Some of the challenges include impacts to streams, cranberry bogs, existing groundwater contamination and variations in flow due to seasonal population.  

For Cape Cod communities, collection of wastewater and recharge to groundwater may be the best alternative to meet requirements of the total maximum daily loads (TMDLs) for nutrients developed as part of the Massachusetts Estuary Program (MEP).  Identifying appropriate sites for groundwater recharge faces many regulatory and technical challenges.  Locations are limited by availability of land and regulatory constraints.  The sole source aquifer on Cape Cod provides good recharge capacity, however, since it is the source for drinking water, locations must be identified which do not impact the existing water supply wells. Locations must also take into account nitrate loads which already exist in the watershed and TMDLs for downstream rivers and embayments in order to meet the requirements of the MEP.  Once a potential site was identified as part of the CWMP process, groundwater modeling was used to understand the recharge capacity of the site and limitations due to flow and nutrient impacts on adjacent wetlands, streams and cranberry bogs.  The Town of Harwich recently completed a draft CWMP and Expanded Environmental Notification Form. The Town of Yarmouth has completed a final CWMP and the project is awaiting funding.