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Williston Water Resource Recovery Facility


Williston, North Dakota

About the Project

The City of Williston’s rapid population growth necessitated a new water resource recovery facility (WRRF).

The City retained AE2S to develop a Preliminary Engineering Report (PER) for the new WRRF, along with preliminary design documents of the selected alternative.

Project Details

Date: 2010 – 2018

Client: City of Williston

Key Project Elements
  • Phased Wastewater Expansion Plan
  • Discharge Permit Modifications
  • Use of Kepner-Tregoe Decision Making Analysis
  • Flexible Design for Future Nutrient Standards

Assessing Treatment Alternatives for Future Needs

AE2S identified future treatment requirements based on capacity needs and treatment discharge levels. Capacity needs were based on population growth patterns. The PER also identified the future discharge limits based on a conversion to continuous discharge, as well as current and projected future regulations, including nutrients.

Treatment alternatives were developed based on the project treatment needs. Each alternative addressed capacity, land needs, costs, and treatment capabilities. Evaluated alternatives included: Extended Aeration/Oxidation Ditch, Conventional Activated Sludge, Integrated Fixed Film Activated Sludge, Membrane Bioreactors, Trickling Filters, and Sequencing Batch Reactors.

In addition to the liquids treatment, solids treatment alternatives were analyzed for disposal of cake biosolids on land application sites as well as the City’s landfill. Based on the evaluation, Oxidation Ditches and Autothermal Aerobic Digestion (ATAD) for Class A cake biosolids was the recommended alternative. This work complements the collection system improvements that AE2S has been doing with the City on their CIP.

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Williston Water Resource Recovery Facility