February 2007, Vol. 19, No.2

Plant Profile

Village of Valders Wastewater Treatment Facility

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Location: Valders, Wis.
Startup date: 1940
Service population: 1000
Number of employees: 1 full-time equivalent
Design flow: 0.255 mgd (965 m3/d)
Average flow: 0.117 mgd (443 m3/d)
Annual operating cost: $225,800

The Village of Valders (Wis.) Wastewater Treatment Facility received the first-place 2006 award for a small advanced wastewater facility from Region 5 of the U.S. Environmental Protection Agency. The agency chose the Valders facility for this honor because of its ability to consistently produce effluent much cleaner than required by its permits.

The facility discharges to a tributary of the Manitowoc River and is required to maintain biochemical oxygen demand and total suspended solids concentrations below 20 mg/L on a monthly average and below 30 mg/L on a weekly average, a minimum dissolved-oxygen concentration of 4.0 mg/L, and a pH reading between 6.0 and 9.0. The facility consistently maintains effluent biochemical oxygen demand concentrations of about 4.0 mg/L and total suspended solids concentrations of 3.0 mg/L. Dissolved-oxygen concentrations are usually about 9.0 mg/L.

The facility combines two activated sludge package plants to treat its influent. One package plant was installed in 1973 and the other in 1995. The 1973 package plant consists of concentric tanks. The outer ring is for incoming wastewater stabilization, reaeration of the return activated sludge, and aerobic digestion of the waste activated sludge. The center tank is the final clarifier. Also in 1973, the facility installed chlorine disinfection and storage and polishing ponds

In 1995, the second package plant was added, and the original package plant was modified to provide additional flexibility, such that both plants can be operated in conventional activated sludge mode.
Covers were provided over both package plants, and provision was made to bypass the polishing pond, as experience had shown that algae blooms in the pond increased the effluent total suspended solids concentration much of the time. The raw wastewater pumping system was completely renovated, and a new liquid sludge holding tank was built.

Regular Maintenance
Valders takes a proactive approach to collection system and facility maintenance. The village includes major collection system maintenance and repairs in its planning each year, including projects to reline or re-lay sections of pipe as needed. Additionally, the village budgets $2500 each year for line cleaning and televising to keep flows moving and detect any problems.

The practice has helped the facility identify problem areas and greatly reduce inflow and infiltration, which reduces operating costs. As a result of these efforts, the facility’s average daily flow dropped from 0.202 mgd (765 m3/d) in 2004 to 0.117 mgd (443 m3/d) in 2005.

On the equipment-maintenance side, the facility has spent 5 years developing a schedule that accounts for all daily, weekly, monthly, and annual maintenance tasks. The schedule has reduced unexpected equipment failures and each year saves the facility several thousand dollars in costs avoided by detecting problems early.

Moreover, regularly scheduled maintenance projects have increased work efficiency and made tasks safer, because needed safety equipment can be checked and prepared in advance of the job.

Steady Upgrades
During the past 5 years, the plant also has switched from manual controls to an automated supervisory control and data acquisition system. The new system controls all operating equipment at the facility and includes an alarm function to let operators know of problems. The old system consisted of flashing lights that staff hoped a neighbor would notice and then call to inform the facility.

The facility also recently installed a standby generator to provide electricity in case of power loss. An automated switch in the generator signals it to turn on if a disruption in the electric flow is detected. The local power company has contracted with the facility for the use of the generator during brownouts for $2800 per year. When the electric supply is tight, the facility will turn on the generator, reducing the demand from the local power grid.

 

 

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The Village of Valders (Wis.) Wastewater Treatment Facility discharges to the Manitowoc River. Because the facility consistently produces effluent much cleaner than required by its permits, Region 5 of the U.S. Environmental Protection Agency in 2006 gave the facility the first-place award for a small advanced wastewater facility.