The City of Siloam Springs teamed with Garver to determine the benefits of adopting reuse of the treated effluent as the primary plant utility water for operations at the Siloam Springs Wastewater Treatment Plant (WWTP) in lieu using and paying for potable water, including sewer fees corresponding to the water usage.
Since the implementation of its custom biological nutrient removal (BNR) improvements, the City’s WWTP continues to produce a high-quality effluent that is second to none in Northwest Arkansas. In fact, the effluent quality is better than most wastewater treatment plants in the area that are currently using filtration for final polishing of the effluent. The liquid process treatment upgrades included modifications to the headworks facility, primary clarifiers, new BNR and CNR processes followed by conventional clarification, and minor modifications to re-aeration and chlorine disinfection process.
Plant records were used to determine average and peak plant water demands and seasonal variations. In addition, flow testing was performed to confirm the water usage. Monthly water usage ranged from approximately 4.5 million gallons to 7 million gallons. The City of Siloam Springs and Garver evaluated alternatives and developed a plan to separate the plant water distribution system from the potable water distribution system (administration facility and emergency eye wash stations/showers) that was implemented during construction.
The recommended alternative included new piping throughout the WWTP including associated valves, fittings, and yard hydrants for additional operations and maintenance, and a new triplex pump station adjacent to the chlorine contact basin. This new pump station pumps treated effluent water from the chlorine contact basin to the upgraded plant water system for use throughout the plant. The pump station included a new building, electrical controls, future SCADA connections, and filtration system for algae control.
The project was awarded to the low bidder in the amount of $409,000, and two other bids were received in the amount of $522,000 and $542,000. Garver’s engineering estimate was $534,000. Construction was managed by the City with assistance from Garver, and work was completed by the contractor without exceeding the original bid/contract amount. The total cost for the project including design, construction, and administration was approximately $500,000. The improvements have reduced the total WWTP average operating expenses by approximately 15% per month. Specifically, most recent data shows a monthly savings of $28,000 to $30,000. Based upon total project costs and cost savings, the project will have a less than two-year payback period.
Phillip R. Patterson City Administrator “This project is proof of the City’s Board of Director’s commitment, and our staff’s commitment, to having sustainable operations, and having those operations run as efficiently as possible.”
Long range future goal is to work on city wide reuse for irrigation and industrial use. New State Regulations will have to be passed like those of others to get approval from ADH and ADEQ to implement City wide reuse.