The Sni-A-Bar Wastewater Treatment Plant (WWTP) serves the nearby cities of Blue Springs and Grain Valley, Missouri. In 2013, the city of Blue Springs completed an expansion project to increase plant capacity and improve effluent discharge, allowing the Sni-A-Bar WWTP to meet more stringent environmental requirements mandated by the EPA and the Missouri Department of Natural Resources (MDNR).
Scope
The initial phase of the project included the evaluation of antidegradation issues associated with increasing the capacity of the plant to accommodate additional growth in Blue Springs and Grain Valley. Consulting engineers, HDR, along with assistance from their subconsultant, Geosyntec, identified low dissolved oxygen (DO) concentrations occurring in Sni-A-Bar Creek, the receiving stream, which could potentially prohibit future plant expansion.
Solution
To address the low DO issues, the expansion project incorporated reed bed technology, an innovative green solution that provides a simple and effective means of wastewater solids treatment and reduces processing costs by creating a small-scale sewage treatment system in a constructed wetland. Reeds planted in specially designed reed beds naturally pull out impurities found in the sludge and transform a wastewater byproduct into a useable material.
The influent pump station at Sni-A-Bar now consists of five Xylem, Flygt brand dry pit submersible N-pumps. The semi-open, self-cleaning impeller on an N-pump represents a patented design innovation that makes the pumps more reliable and energy-efficient. The leading edges of the impeller vanes pass across a stationary relief groove that clears any snared fibrous solids, grease, or sludge, creating a self-cleaning flow path through the pump.
The station also includes dual force mains and flow metering, which discharge to the new headworks building. Programmable logic controllers (PLCs) had previously been used to control the headworks pumps, but their use at the plant had become problematic.
This proactive approach to wastewater treatment is nothing new to the staff at the Sni-A-Bar plant. In 2007, at the recommendation of HDR, plant operators added a pair of Xylem technologies that remain in operation today: Flygt pumps to increase wet weather pumping capacity at the influent pump station at the plant headworks and Flygt MultiSmart pump station controls.
As part of the plant improvement process, the consultant and plant operators decided to replace the PLCs with Flygt MultiSmart pump station controls. Simple to set up and use, these station controls provide hundreds of features that not only maximize pump station efficiency, but also save time and money by preventing clogging and nuisance call-outs. Multiple set-point profiles allow remote switching on specific dates and times for a variety of specific operations, for example, spill management.
Result
In addition to expanding the plant design average capacity from six to 10 million gallons per day (MGD), the improvements have increased design peak capacity from 18 to 36 MGD. Flows that exceed 36 MGD are stored and treated through the plant after the peak wet weather event.
