Sewer plant construction to begin this spring

Efforts to gain state approval for construction of a new $13.7 million sewage treatment plant in Maryville are well ahead of schedule, and work is expected to begin early this spring.

Mike Kalis of Omaha, Neb.-based HDR Engineering, which is designing the plant, updated the City Council on the project late last week. He said plans and specifications have been declared "approvable" by the Missouri Department of Natural Resources, a step that should make the official go-ahead more or less a formality.

After the plans are approved early in 2013, the next step will be issuance of a state operating permit, which will allow the city to seek bids from general contractors.

Kalis said construction is expected to last 14 to 16 months, which means the plant should be operational well before a negotiated April 2015 target date for meeting new environmental regulations regarding allowable ammonia levels that went into effect last spring.

Completing those negotiations, and thus avoiding fines that could have been levied against the city by MoDNR, was one of the primary reasons HDR was brought on board a year ago. The change came after the council fired its original engineer, Universal Asset Management of Harrisonville, over missed deadlines.

In addition to such "regulatory support services," HDR was originally hired to conduct a facility plan review and design. Those tasks revealed that a proposed upgrade of Maryville's existing lagoon-based system was impractical. Instead, the council elected to approve construction of a "mechanical" facility at significantly greater cost.

Rather than letting wastewater toxins break down naturally in lagoons, the city will now treat sewage in large, mechanically aerated cement tanks impregnated with anaerobic bacteria capable of converting ammonia and other toxins into harmless compounds.

Last week, the council approved a new contract with HDR that calls on the company to assist with the construction phase of the project. The agreement includes a not-to-exceed fee of $867,452, or about 6 percent of the plant's total cost.

In his report to the council, Kalis said Maryville will be able to retain its existing lagoons as part of the new system. The basins will be used for sludge storage and storm overflow.

Utilizing the lagoons in that manner will preclude construction of several large tanks and save the city between $4 million and $5 million, Kalis said. He added that sludge will have to be dredged from the basins every couple of years and is typically used as crop fertilizer.

When completed, the new plant will consist of aeration tanks, an office/laboratory building and another structure required to house part of the treatment operation. Construction will begin with earthwork required to raise the site several feet above the 100-year flood plain of the One Hundred and Two River.

Like the existing lagoons, the new plant will be located just east of town a few hundred yards south of Highway 136.