H-20 Chambers Installed In WWTP Dispersal System

The Town of Kingston, Massachusetts, needed to expand its wastewater infrastructure to accommodate community growth while addressing long-standing environmental concerns. High nitrogen loads from aging wastewater infrastructure had contributed to impacts on local waterways, including shellfish bed closures and recurring beach closures.

To address these challenges, Kingston developed a new centralized wastewater treatment plant and an innovative subsurface disposal recharge system designed by CDM Smith. The expanded system increased design flow to 700,000 GPD and created capacity for future connections from homes and businesses currently relying on the older sewer system or traditional onsite systems.

The recharge site features six large drainfield beds containing more than 13,000 Infiltrator High Capacity H-20 chambers, along with a new 3,600-foot force main. The H-20 chambers were selected for their 32,000-pound-per-axle rating, providing the strength needed to accommodate potential vehicle traffic over the system.

Construction included land clearing, excavation, coarse aggregate installation, chamber placement, geotextile filter fabric and geogrid installation, distribution boxes, and force main construction.

Beyond increasing wastewater capacity, the subsurface discharge approach is designed to help lower nitrogen levels along the shoreline while allowing the land above the system to remain available as community open space, including future walking trails. With minimal operation and maintenance requirements for the disposal beds, the project demonstrates how large-flow subsurface discharge systems can provide practical infrastructure improvements alongside economic and ecological benefits.