11/20/2025 CONSERVATION COMMISSION Minutes

Home Browse Search

Town of Mashpee Conservation Commission 16 Great Neck Road North Mashpee, MA 02649 single on-site systems serving individual homes, cluster systems serving a small group of properties, and "ecological sanitation" approaches such as urine-diverting toilets, composting toilets, and incinerating toilets. With on-site or ecological systems, infrastructure consists less of pipes and plants and more of people and information: staff must visit numerous locations to monitor and maintain systems rather than operating a single centralized facility. Turning to ecological sanitation, Mr. Baumgaertel described urine diversion as an emerging tool with substantial nutrient-reduction potential. Specialized fixtures separate urine from the rest of the wastewater stream so that it can follow a different treatment and reuse pathway. He noted that urine contains roughly 80- 85% of the nitrogen and a similar share of the phosphorus in domestic wastewater, the same nutrients that appear as N-P-K values on fertilizer bags. Current work with the Green Center in Falmouth and the Rich Earth Institute in Vermont is exploring how to collect, treat, and reuse urine as fertilizer on a larger scale. Early estimates suggest that installing urine-diverting fixtures and a storage tank in a small, one-bedroom home could cost on the order of$10,000—$15,000, in addition to maintaining a Title 5 system to handle graywater. He stressed that urine diversion would not replace sewers or I/A systems,but could complement them, much like solar panels complement the electric grid by reducing load. Mr. Baumgaertel then reviewed how nutrients behave in a conventional Title 5 septic system. A standard system consists of a septic tank and a soil absorption area or leach field. In the tank, about 25% of phosphorus is removed with settled solids, but essentially all nitrogen passes through, changing chemically from urea to ammonia. The leach field converts most of that ammonia to nitrate in the unsaturated soil. Standard Title 5 systems remove only about 35% of incoming nitrogen overall, with the remainder traveling as nitrate to groundwater and eventually to estuaries. Phosphorus removal is also poor: beyond the roughly 25% captured in tank solids, most phosphorus (often around three-quarters of the incoming load) passes through sandy Cape Cod soils, which have low capacity to bind phosphorus. New systems may temporarily remove more phosphorus until the soil's limited storage capacity is exhausted. He contrasted conventional systems with"black box" I/A technologies—tank-based nitrogen-removal units installed between the septic tank and leach field. Older FA systems, such as FAST and Bioclere units, were originally designed to remove basic wastewater pollutants (biochemical oxygen demand and total suspended solids) rather than nitrogen. They incidentally remove some nitrogen but typically only achieve effluent concentrations around 19 mg/L, which the data show is not sufficient to solve watershed nitrogen problems. Within the last five to seven years, newer technologies have been developed that specifically target nitrogen, including the Nitrex system(by Lombardo Associates) and the NitROE system (by KleanTu). Both use a wood-chip—based denitrification process and, in testing, have demonstrated approximately 85-90% nitrogen removal, with average effluent nitrogen concentrations in the range of 7-8 mg/L over a full year—sometimes as low as 3 mg/L in summer, and somewhat higher (10-15 mg/L) during winter when microbial activity slows. Mr. Baumgaertel described the Massachusetts Department of Environmental Protection (MassDEP) approval process for FA systems. Technologies begin with"pilot" approval, allowing up to 12 installations to demonstrate that they are at least no worse than a standard system. To progress to general nitrogen-removal approval, a system must obtain"provisional" approval, install at least 50 units, and collect three full years of monitoring data on all of them. MassDEP then analyzes that dataset and assigns an official effluent nitrogen concentration for regulatory purposes. At present, both Nitrex and NitROE are still under provisional approval, with provisional effluent numbers of 10 mg/L (Nitrex) and 11 mg/L (NitROE), compared to 19 mg/L for older I/A systems. NitROE is further along in the process, with roughly 200 installations between Cape Cod and Martha's Vineyard and near completion of its three-year monitoring period. Mr. Baumgaertel expects MassDEP will issue general approval for Nitro in the near future, though the final effluent concentration assigned will depend on MassDEP's analysis. He noted that towns such as Falmouth have used MassDEP's 3