Whitewater River Pollution Control Facility Planning
Dover, Eyota, St. Charles Area Sanitary District

Facility Planning Saves Money

The Dover, Eyota, St. Charles Area Sanitary District (DESCASD) operates the Whitewater River Pollution Control Facility which is located in St. Charles, MN.  Facility planning efforts have detailed a number of improvements to be made at the Whitewater River Pollution Control Facility.  Increasing wastewater flows and loads have made it necessary to expand the existing facility to maintain effluent quality and its impact on the receiving water.  As part of the planning efforts and negotiations with the Minnesota Pollution Control Agency (MPCA) for preliminary effluent discharge standards, the District was able to relax their effluent CBOD discharge standard from 5 mg/l to 15 mg/l with the acceptance of a more stringent ammonia standard.  This was significant, as it allowed the District to eliminate their existing effluent filters while meeting both their new CBOD and ammonia standards with their extended aeration activated sludge system.  In addition to the planning efforts, AE2S helped the District prepare their new NPDES permit application as well as provide support services through the environmental review process.

Phase Approach Achieves Affordability

The expansion and upgrade has been proposed to occur in four phases.  The first phase has already been completed, and included a new preliminary treatment building with influent flow measurement and sampling, one rotating fine screen, re-use of one climber screen, vortex grit removal and grit washing.  The proposed second phase of the expansion and upgrade will allow the facility to treat an average wet weather flow (AWWF) of 2.18 million gallons per day (MGD).   The third phase of the expansion and upgrade will not increase the capacity of the facility, however, biosolids processing and storage operations will be improved.  The fourth phase of the expansion and upgrade will allow the facility to treat an AWWF of 2.54 MGD.  Phasing of the project keeps the project affordable for existing residents as well as the large industrial user which contributes a significant amount of the influent loadings to the facility.

Timely Completion of Design Aids in State Approval Process

In 2005, DESCASD authorized AE2S to design second and third phases that were proposed in the facility plan.  The proposed project contains upgrading the existing oxidation ditches and final clarifiers, adding a new oxidation ditch, final clarifier, chlorination/dechlorination system, cascade aeration, effluent flow metering, chemical phosphorus removal, return and waste activated sludge pumping facilities, aerated sludge holding tanks, glassed lined steel sludge storage tank, reed drying beds, sludge mixing and transfer station, standby power, and SCADA system.  The plans and specifications have been submitted to the MPCA for review and approval.  The project is anticipated to bid in October 2006 with construction through 2008.