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Williston Water Treatment Plant Expansion


Williston, North Dakota

About the Project

The expanding oil and gas industry in northwest North Dakota strained water systems’ abilities to keep up with domestic and industrial water needs.

As the economic hub of the region, the City of Williston continues to experience considerable growth, and it’s anticipated that the growth will continue.

Exacerbating the domestic water demands are industrial water demands from the oil and gas industry within the region, estimated at over 40 million gallons per day (MGD).

Project Details

Date: 1999 – Present

Client: City of Williston

Key Project Elements
  • Control System Programming
  • HMI Improvements
  • Ongoing Support
  • Extensive Expansion/Renovation

Master Plan Implementation

In December 1999, AE2S completed the Williston Regional Water Treatment Plant (WTP) and Transmission Line Master Plan (1999 Master Plan). The 1999 Master Plan included interim conclusions and recommendations, developed costs for alternative solutions, and recommended improvements to resolve numerous challenges.

The 1999 Master Plan also included an improvement prioritization plan that the City utilized as they worked with funding and regulatory agencies to complete needed improvements.

Several projects were implemented as the result of the 1999 Master Plan, including the Williston Phase I project, which addressed compliance issues with the Interim Enhanced Surface Water Treatment Rule and the Phase II Improvements, which included an 18,000-square-foot addition that included a new ActiFLO pretreatment basin, solids contact basin, and ultraviolet light disinfection reactors, and a residuals management project which added nearly 43 acres of ponds to help treat WTP residuals.

The development of the water model as part of the 1999 Master Plan was key in helping evaluate the best alignment for their new transmission pipeline to deliver potable water from the existing WTP to the distribution system.

The 1999 Master Plan, however, did not account for providing regional water service of the magnitude required to serve extreme growth and the industrial water demands of the oil industry.

Master Plan Update

The City of Williston retained AE2S to prepare a Regional WTP Master Plan Update (Master Plan Update) in response to a concept where the WTP would serve as the source for a new regional water system.

The plan included: (1) preparation of anticipated water demands for the City and the new regional water system for specific planning horizons; (2) development of water supply and treatment improvement and expansion concepts for the Williston Regional WTP and intake system to meet the anticipated water demands; (3) preparation of opinions of total probable project costs for the water supply and treatment concepts; and (4) preparation of estimated life cycle cost comparisons and recommendations for improvements to the Williston Regional WTP and intake system. The work completed was presented in a series of technical memoranda.

Planning Efforts Realized

Based on the results of the Master Plan Update, design of a Phase III project to add a 1-million-gallon finished water clearwell, expand the plant’s filtering capacity with the addition of six dual media filters, and add a new filter backwash recovery system began.

Construction began in 2012 and the filters were placed in operation at the end of 2013. In an effort to meet the increasing water demand, the design of a Phase IV project was completed in the fall of 2012, with construction beginning shortly thereafter.

The Phase IV project included the addition of a third solids contact softening basin and a new sludge pump station. In addition, the plant’s electrical system was completely overhauled, including the installation of two large diesel generators capable of providing standby power for the plant, as well as excess power that will be sent back into the electrical grid.

Phase IV project recently completed in 2018, increased the Williston Regional WTP capacity to 21 MGD.
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Williston Water Treatment Plant Expansion