RIRRC Leachate Pretreatment Facility (RI)

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The RIRRC, which handles most of Rhode Island’s municipal waste and recycling from neighboring cities and towns, needed to design and build a 0.650-mgd treatment plant to comply with projected changes in the discharge standards for disposal of wastewater, including leachate, into a public sewer system. Specifically, the new facility needed to pretreat landfill- related leachate from RIRRC’s Central Landfill to help the RIRRC comply with projected changes in nitrogen-discharge standards set by the Rhode Island Department of Environmental Management (RIDEM) for the disposal of wastewater.


Ramboll (formerly OBG), with their contracting partner, designed and built a $27 million, state- of-the-art leachate-pretreatment plant. Using green principles, the plant treats wastewater generated by the landfill before it is released into the public sewer system via the Field’s Point Treatment Facility operated by the Narragansett Bay Commission (NBC). The contract was awarded by a pre-qualification approval process (SOQ) followed by a detailed fixed-price design-build procurement process.

The new facility’s treatment process was designed with sequencing-batch-reactor (SBR) technology that could process up to 650,000 gallons of wastewater a day, reducing biochemical oxygen demand (BOD), total suspended solids, ammonia and nitrate, to comply with enhanced nutrient-removal pretreatment standards. The main components of the treatment process are: influent equalization and pumping, three 1.3-million-gallon SBRs and ancillary equipment, bulk-chemical storage and metering, effluent equalization and pumping, sludge holding and dewatering, a fully integrated control system consisting of a programmable logic controller (PLC) and a supervised computer and data-acquisition control system (SCADA), and electrical distribution and standby power.

In addition to providing the design for the facility, Ramboll (formerly OBG) also obtained regulatory permit approvals from RIDEM, designed the integrated instrumentation and control SCADA system, and performed commissioning and operational start-up services for all equipment and systems.


The new plant is allowing for more environmentally friendly processes, advancing regulatory compliance, and saving money by treating the leachate at the source. The overall project will improve water quality by reducing the BOD and the nitrogen load discharged from RIRRC to publicly owned treatment works (POTWs) located downstream. With sustainability in mind, the project is designed to LEED Silver standards and with architectural details to reduce consumption of natural resources. The new plant began operating in March 2015, allowing RIRRC to continue its mission of providing solid waste disposal services for the Rhode Island community, which is supported by the employment of more than 200 people.

“The building has been designed with great detail paid to various architectural and operational considerations—water efficient landscaping, construction waste, and air quality management procedures. Water use reduction and the use of building materials with recycled content will all be incorporated into the building’s construction. These considerations, among many others, will provide for a reduced consumption of natural resources over time.”
—Mike O’Connell, Executive Director for RIRRC