The City of Blue Springs (City) is in need of additional infrastructure to accommodate growing wastewater needs as development progresses around the Kansas City metropolitan area. To accommodate anticipated growth, the City is planning an expansion and upgrade to their current wastewater treatment facility (WWTF), which discharges into Sni-A-Bar Creek. Perennial reaches of Sni-A-Bar Creek are included in Missouri’s impaired waters list due to low dissolved oxygen (DO) concentrations. Geosyntec and agency scientists believed that Sni-A-Bar Creek did not attain statewide DO criteria naturally during summer conditions as a result of shallow depths, high residual sediment oxygen demand, low reaeration, and transient stagnant features such as beaver dams and backwater areas. To permit expansion of a WWTF that discharges to impaired reaches, state regulatory policies require intensive water quality study and evaluation of attainable conditions. HDR | Archer Engineers retained Geosyntec on behalf of the City of Blue Springs to evaluate water quality conditions within this basin, develop site-specific dissolved oxygen targets, and perform water quality modeling to assist in wastewater planning and permitting efforts.
Geosyntec’s Scope of Services
Geosyntec’s objective was to evaluate attainable water quality conditions within the basin and provide the regulatory tools needed to support wastewater infrastructure planning for the City and nearby communities. We performed one of the most intensive wasteload allocation (WLA) monitoring studies ever conducted in Missouri to verify a QUAL2K water quality model. Our WLA study efforts included multiple time-of-travel dye studies, diel DO and water chemistry measurements, flow and hydrogeometry characterization, and reaeration calculations. Geosyntec’s model results were used to quantify attainable DO concentrations and demonstrated that no proven or practical treatment technologies would likely achieve Missouri’s statewide DO criterion.
Geosyntec recognized from the beginning that a site-specific DO criterion was one of the few regulatory options available to the City that would allow expansion of the Sni-A-Bar WWTF. Therefore, we prepared and implemented a site-specific DO criteria study in conjunction with the WLA studies. We selected suitable DO reference sites, considered the best available representatives of natural conditions, based on physical and biological habitat assessments and GIS analysis. After site selection, we conducted extensive long-term diel DO measurements in support of alternative DO criteria. Geosyntec’s results from the study confirmed that conditions within this region preclude the attainment of Missouri’s DO criteria on a consistent basis, and, ultimately, formed the basis for alternative site-specific criteria. Additionally we used study and model results to support the development of one of Missouri’s first antidegradation reviews.
Geosyntec’s precedent setting study and negotiations represent one of the only site-specific criteria approved by the Missouri Clean Water Commission (MCWC), thereby allowing Blue Springs to expand wastewater treatment capacity and prevent a large capital outlay associated with expensive and marginally beneficial treatment trains.