Ready for Growth: Green Solution Paired with Plant Upgrade Helps Wastewater Facility Meet Environmental Requirements and Sustain Future Development

Feb. 11, 2015
The city of Blue Springs, Mo., recently completed an expansion project at the Sni-A-Bar WWTP to both sustain development and improve effluent discharge. The upgrade increased capacity, meeting growth needs for the next two decades, and allowed the utility to address more stringent EPA and MoDNR environmental requirements. The project, completed in 2013, incorporated an innovative green solution for wastewater solids treatment, which reduces the processing costs.


The city of Blue Springs, Mo., has recently completed an expansion project at the Sni-A-Bar Wastewater Treatment Plant (WWTP) that was needed to both sustain development and improve effluent discharge. The facility treats sewage from the cities of Blue Springs and Grain Valley. The plant expansion increased capacity, meeting growth needs for the next two decades, and allowed the utility to address more stringent environmental requirements as mandated by the Environmental Protection Agency EPA (EPA) and Missouri Department of Natural Resources (MoDNR).

This project, completed in 2013, incorporated an innovative green solution for wastewater solids treatment, which reduces the processing costs. The new green feature is the implementation of a constructed wetland known as reed bed technology. Specially designed reed beds offer a simple, robust and cost-effective means of wastewater solids treatment. The reeds planted in the beds naturally extract impurities found in the sludge and transform a wastewater byproduct into a useable material.

Artificial swamps, or constructed wetlands, use reeds or other marshland plants to form part of a small-scale sewage treatment system. Water trickling through the reed bed is cleaned by microorganisms living on the root system and in the litter. These organisms utilize the sewage for growth nutrients, resulting in a clean effluent. The process is similar to conventional aerobic sewage treatment, as the same organisms are used, except that conventional treatment systems require artificial aeration. The Sni-A-Bar WWTP sludge reed beds consist of 16 cells that provide a total bed area of about four acres.

Sni-A-Bar's PLCs were replaced with Flygt MultiSmart pump station controls, which provide hundreds of features that not only maximize pump station efficiency but also save time and money by preventing clogging and nuisance call-outs.

This kind of proactive approach to wastewater treatment is not new to the staff at the Sni-A-Bar treatment plant. In 2007, for example, they utilized a pair of Xylem Flygt pumps and MultiSmart pump station controls to improve plant operations, which served the influent pump station at the plant headworks.

For over 30 years, Blue Springs has been turning to consulting engineers HDR for multiple wastewater treatment and conveyance improvement projects. In 2007, HDR performed engineering services for the construction of a new influent pump station to increase the treatment plant's wet-weather pumping capacity to 54 million gallons per day (MGD), as well as a plant expansion from 5- to 10-MGD design average flow. Both facilities are currently in operation. These improvements were achieved under the direction of HDR Project Manager Brandon Coleman and Blue Springs Director of Public Works Chris Sandie.

The initial phase of the plant expansion project included the evaluation of anti-degradation issues associated with increasing the capacity of the plant for additional growth in Blue Springs and Grain Valley. HDR, along with assistance from its sub-consultant Geosyntec, identified low dissolved oxygen (DO) issues occurring in Sni-A-Bar Creek -- the receiving stream -- which could potentially prohibit future expansions of the plant.

Perennial reaches of Sni-A-Bar Creek are included in Missouri's impaired waters list due to low DO concentrations. Geosyntec and DNR scientists believed that Sni-A-Bar Creek did not naturally attain statewide DO criteria 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 WWTP that discharges to impaired reaches, state regulatory policies require intensive water quality study and evaluation of attainable conditions.

Geosyntec's study efforts included multiple time-of-travel dye studies, diel DO and water chemistry measurements, flow and hydrogeometry characterization, and reaeration calculations. 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. It was recommended that the city request a variance for in-stream DO levels from both the EPA and MoDNR and that the plant be upgraded to meet tertiary treatment levels. The organizations agreed, and the variance was later approved.

The Sni-A-Bar Wastewater Treatment Plant in the city of Blue Springs, Mo.

To fund the project, the consultant completed a facility plan and helped the city receive over $36 million in State Revolving Fund low-interest loans, which included a $3-million grant from the American Recovery and Reinvestment Act of 2009.

In addition to expanding the plant's design average capacity from 6 to 10 MGD, the improvements included increasing 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. The influent pump station now consists of five Flygt-brand, dry-pit submersible N-pumps.

The semi-open, self-cleaning impeller on an N-pump represents a patented innovation that makes them more energy efficient and reliable. The design keeps the leading edges of the impeller vanes unobstructed where fouling often sets the stage for clogging. These leading edges 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.

The new facilities now also include the following:

  • A multiple rake climber coarse screen for protection
  • New headworks with 1/4-inch fine screening and grit removal
  • Two new aeration basins with fine-bubble, retrievable diffusers
  • Provisions for future biological nutrient removal basins
  • Two new 125-foot-diameter final clarifiers
  • New tertiary disc filters
  • Ultraviolet disinfection
  • Effluent pumping and aeration
  • Two sludge digestion/storage basins

Programmable logic controllers (PLCs) had previously been used to control the headworks pumps, but their use at the plant had become problematic. Taking advantage 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 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 also allow remote switching on specific dates and times for a variety of specific operations such as spill management.

Control panel costs are reduced due to built-in functionality in the MultiSmart controls such as three-phase current monitoring. The remote control feature reduces maintenance and frequency of site visits, while the built-in local SCADA removes the added costs of HMI hardware and software.

The pairing of constructed wetlands with improvements and capacity increases to the fundamental infrastructure of the Sni-A-Bar WWTP have now fully prepared the cities of Blue Springs and Grain Valley to meet all environmental regulations as well as sustain future development around the Kansas City metropolitan area.

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