Affordable Wastewater Disposal for Coastal Households Adapting to Sea Level Rise

Rising sea levels and king tide flooding in coastal areas across America are saturating onsite wastewater disposal systems (OSDS), resulting in the degradation of coastal ecosystems and 200,000+ illnesses annually. Many States are mandating system upgrades, with 88,000 upgrades required by 2050 in Hawaii alone. Unfortunately, existing upgrade options are unaffordable for 97% of Hawaiian homeowners and offer poor performance for coastal properties with high groundwater levels. In response to this pressing issue that will cost Hawaiian homeowners an estimated $1.75B between now and 2050, WaiHome LLC is developing an aboveground and affordable wastewater disposal system for coastal households adapting to sea level rise. Under this Phase II SBIR project, WaiHome will test the comparative performance of its RAIL proof-of concept prototype developed in Phase I relative to conventional absorption bed disposal in the six dominant soil texture groups in Hawaii. WaiHome will also investigate opportunities to refine its prototype design in preparation for commercial manufacturing and installation. Phase II research will culminate in a Design Validation Testing program that will see the installation and monitoring of demonstration units on three residential properties and one city wastewater treatment plant. This program is consistent with standard permitting pathways for new disposal products. This Phase II project will deliver a minimum viable product with design specifications, bill of materials, commercial manufacturing plan, and maintenance guidelines. Installation guidelines and recommended loading rates will be developed for six soil texture groups dominant in Hawaii. Performance relative to conventional gravel-based and leaching chamber absorption bed designs will be established to further inform the development of system loading standards. It is anticipated that by eliminating the groundwater infiltration and disturbances to the soil-water interface inherent to excavations, the RAIL will demonstrate reduced saturation of the soil-water interface and thereby reduced propensity for clogging. The results of this project will be presented to the Hawaii Department of Health (DOH) as WaiHome begins the process of entering design standards for the RAIL into the Hawaii Administrative Rules. The RAIL will cut the cost of disposal system installation in Hawaii by more than half and make new OSDS accessible for the 97% of Hawaiian cesspool owners who currently can’t afford to comply with the statewide upgrade mandate.