Owner’s Engineer for WWTF DBO Improvements

Woonsocket, RI Wastewater Treatment Facility DBO Procurement

The City of Woonsocket selected Weston & Sampson to provide technical assistance with the procurement of a 20-year Design-Build-Operate (DBO) contract for the upgrade and long-term operation of their Wastewater Treatment Facility (WWTF). The existing WWTF is an activated sludge treatment plant serving the City of Woonsocket, Rhode Island and three nearby communities with a permitted monthly flow of 16 million gallons (mgd) per day. The WWTF also receives flow from the independently owned and operated Synagro sludge dewatering and incinerator facility located at the site. In 2008, the city signed a Consent Agreement (CA) with the Rhode Island Department of Environmental Management (RIDEM) to implement a WWTF upgrade to meet new much more stringent Rhode Island Pollutant Discharge Elimination System (RIPDES) permit limits for nutrients and to modernize other existing process areas. The new permit limits included the region’s lowest limits to date for effluent nitrogen (less than 3 mg/l total N) and phosphorus (less than 0.1 mg/l P).

The procurement process was undertaken with a fast-track schedule to meet the requirements of the CA and a city-imposed host fee payment requirement. Weston & Sampson provided technical assistance in development of the Request for Proposals (RFP), subsequent addenda, and the agreement for DBO Services; evaluated proposal packages for technical process merit; and interviewed proposers. The review team had only four weeks to review the information provided, evaluate and rank the proposals based on the pre-established criteria, and make a recommendation to the Wastewater Advisory Committee as well as the city council. The evaluation and ranking criteria included:

  • Ability of the proposed facility to efficiently and effectively meet performance requirements
  • Flexibility to handle variations in influent characteristics and quantity
  • Reliability of the proposed facility to effectively meet interim and future RIPDES permit requirements
  • Measures for energy and chemical management
  • Reasonableness of operation and maintenance plan for the facility
  • Understanding of regulatory reviews, approvals, and permitting process
  • Approach for odor control, noise, and other nuisance items minimization

While a proposed technical approach was provided by way of a previously developed draft facility plan, the RFP was specifically written to allow alternate technical approaches including side stream treatment of recycles and the high strength Synagro flows to maximize the opportunity for further process optimization and potential cost savings for the city over the life of the project. This approach resulted in proposals that employed several different treatment process flow schemes.

After extensive technical review, Weston & Sampson identified the proposal that provided the most advantageous upgrade for the Woonsocket WWTF. We subsequently assisted in negotiating the final DBO contract. Weston & Sampson continues to provide technical support and management assistance to the city related to project development, regulatory coordination, funding assistance, and process design through project development and implementation.


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Posted in Construction, Construction Oversight, Design/Build/Operate, Wastewater, WWTreatment and tagged , .