Modeling for Wastewater Treatment in Phase 3 FASTER, CHEAPER, FAIRER. We have estimated the number of households in the Phase 3 area within the Three Bays watershed. The latest Phase 3 area includes some parcels outside of the watershed itself. Here are some of the baseline numbers: • Phase 3 encompasses 1,991 parcels. • Phase 3, Three Bays Watershed: 1,737 parcels. • The average year a house was built in the area is 1977. • For a large portion of the homes in this area, the time to travel is 10 years or less. • Connecting 1,737 homes to sewer at current prices would cost approximately $243 million. • Phase 3 starting date is likely to be in the 2040’s. The Cape’s housing crisis, a warming climate, and our wastewater clean-up mandate suggest looking at our overall problem with new urgency. Here are a few things to consider: • EIA technology can achieve a better than 95% reduction in nitrogen. • EIA technology may be 1/3 the cost of sewer expansion. • New state tax incentives of up to $18,000 enhance A different approach is to use EIA systems for EIA affordability for some homeowners. wastewater treatment while modeling potential • Data suggests that existing septic systems financial incentives to lower the cost and accelerate (cesspools and Title 5s) in the Phase 3 area will adoption. require replacement prior to sewer arrival given the age of the properties. One approach could incorporate the need for more A simplistic analysis of sewer expansion alone to housing with the ability to add an Accessory Dwelling treat household wastewater in the Phase 3 area Unit (ADU) to a property. We posit that in the Phase would indicate that the total cost in today’s dollars 3 area, 509 of the 1,737 properties could add an would be $243 million. This is using a cost $140,000 Accessory Dwelling Unit (ADU see glossary, page 10) per parcel as the baseline for the 1,737 parcels based on lot size and number of bedrooms. We show in question. Individual homeowners would be these locations on the map above. responsible for paying $20,000 of the $140,000 to Based on existing water and wastewater data we can connect to the sewer. Therefore, about $35 million conclude that the best EIA technology can reduce would be shouldered by homeowners and $208 nitrogen by 95% or more and adding an ADU would million by all the town’s taxpayers. still lead to a net reduction of 80% or more. 6 | Barnstable Clean Water Coalition | Fall/Winter 2025 BCleanWater.org