Even as the plans for the new Holmen wastewater treatment plant are being finalized, the Holmen Public Works Committee voted to recommend the village board approve a $45,000 change to the blueprints.
At their Feb. 1 meeting, committee members learned about new technology recently developed for removing phosphorus from wastewater. While the change in the design will be an eight percent increase in the costs for the new treatment plant, the newer system is anticipated to be more economical in the long run.
“If we spend this $45,000 now, it’ll save us millions of dollars down the road,” said Holmen Village Administrator Scott Heinig. “We didn’t have this information before. It was just refined at the end of last year.”
According to Heinig, the modified engineering for the wastewater treatment plant affects just one aspect of the entire plant design, about one-eighth of the entire plan design. The additional cost is about an eight percent increase to the overall contract to allow for the new design.
The designers at Short Elliott Hendrickson, Inc. had originally proposed a cloth disc filter system for phosphorus removal. The design firm now recommends installing an “up-flow” sand filter system instead.
Reducing phosphorus levels in water discharged from wastewater treatment and other sources has been a goal of the Wisconsin Department of Natural Resources. Phosphorus has been identified as the cause for algae blooms in the state’s lakes and ponds and the dead zone in the Gulf of Mexico.
The state has set a standard of less than 0.1 mg/l for phosphorus emissions from treatment plants. Most treatment plants have been using biological or chemical processes to reduce phosphorus in the water discharged into streams, but that technology has only been effective at reducing levels to 1.0 mg/l. To meet a 0.1 mg/l standard, treatment plants need to add advanced filtration systems to their facilities.
The village’s current wastewater treatment plant is 36 years old and is reaching the end of its serviceable life and capacity to serve Holmen’s growing population, according to village officials. The new plant is being designed to handle a population of between 14,000 and 15,000.
Construction of the new plant has been estimated at $14.5 million. The village hopes to begin construction on the new plant this spring with completion sometime in the fall of 2019.
In his updates to the committee, Holmen Public Works Department Director Dean Olson informed the committee that the village’s wastewater treatment plant has been accepting sludge from septic tank pumpers.
“Haulers are bringing in loads,” said Olson. “The sludge helps the (Holmen wastewater treatment) plant work well. It’s kind of a good relationship.”
Water reservoir roof
The public works committee also learned about new technology regarding rubber membrane roofing proposed for replacing the roof on water reservoir #2.
“Replacing the roof is DNR required; it’s an enforcement item,” said Olson. “The new membrane has a 10-year life.”
The liquid rubber membrane is installed by spaying the compound onto the water tower’s roof. Water Tower Clean and Coat, Inc. of Lodi proposes to put two layers on the reservoir to achieve a 100 mil thick coating.
Any future repairs to the roof membrane would only require an additional layer to be sprayed on top of the previous layer. Olson estimated future applications could run about $10,000 as the previous layer wouldn’t need to be removed.
The committee voted to send the proposal for the roof repair on to the Holmen Village Board with its recommendation to approve the $24,800 bid. The proposal cost includes removing and disposing of the existing roofing membrane, pressure washing the water tower’s roof, caulking cracks and applying the two layers of the roofing material.
The HPWC also gave its OK to purchasing 31 stop signs at a cost of $2,117. The signs would be attached to traffic light poles in the village to be used in the event the lights don’t work because of a power outage.