Underground city overflow tank to hold 5 million gallons

By: fioreMarketing | January 24, 2018 | Original Article

CUMBERLAND — An underground holding tank being buried in South Cumberland will hold 5 million gallons of sewer and storm water runoff once installed.

Placed beneath the basketball courts at South Cumberland’s Mason Sports Complex, the massive storage tank might sound like a unusual idea, however officials say the plan will go a long way in cleaning up the Potomac River.

During periods of heavy rain, the storage tank will hold stormwater and sewer overflow preventing the excess effluent from flowing into the North Branch of the Potomac River. Once captured in the tank, the effluent can be treated at the nearby Municipal Wastewater Treatment Plant before being released into the river.

Workers with Leonard S. Fiore Inc. are currently digging a hole — larger than a football field and 80-feet deep — to hold the storage tank. Crews are using massive John Deere track excavators to do the work with terraced roads created to get the excavators into the giant hole.

“It’s a very big project,” John DiFonzo, city engineer, said. “They are moving a lot of earth there.”

The 5 million gallon tank, consisting of separate chambers, will be trucked in and assembled.

Fiore won the contract to do the work when its $26.4 million bid was accepted in 2016. Additional engineering costs will bring the total price tag to nearly $30 million.

“What’s in the tank will mostly be rainwater,” DiFonzo said. “It gets stored in the tank and over time we can treat it at the (wastewater treatment) plant. When it is raining you can’t treat it at the speed it is coming through.”

Cumberland, and other municipalities along the river, have antiquated underground piping grids known as CSO (Combined Sewer Overflow) systems. CSO systems feature stormwater and sewage lines that are combined. During periods of heavy rain, the aging CSO systems are designed to release pressure by allowing overflow effluent to be released into the surrounding waterways. Locally, overflow effluent is released at stations, known as CSO outfalls, along Evitts Creek, Wills Creek and the North Branch of the Potomac River.

Several municipalities in Maryland, in addition to Cumberland, are under pressure from the state to abate their antiquated CSO systems.

DiFonzo said an effort to separate all combined storm and sewer pipes beneath Cumberland would cost more than $250 million making it cost prohibitive.

The state has approved the storage tank system as an alternative. When the project is completed next fall, DiFonzo said it will reduce the amount of pollutants flowing into the Potomac River by 85 percent.

DiFonzo said two of largest contributors to overflows are a CSO near the Municipal Wastewater Treatment Plant, which carries South Cumberland effluent, and a large CSO behind Canal Place, called the Mill Race CSO, with handles effluent from the downtown.

According to DiFonzo, once installed, the storage tank will nearly eliminate overflow from the CSO near the treatment plant.

“We are thankful for the funding from the state, otherwise we couldn’t do it,” DiFonzo said.

Funding for the project will be split with 87.5 percent coming from the state’s Bay Restoration Fund and 12.5 percent from a low-interest State Revolving Loan package.

Installation of the storage tank in South Cumberland is a first phase. The project is part of a larger $90 million CSO cleanup project.

A second phase will address the Mill Race CSO outfall. It requires the construction of a 78-inch pipeline from the Canal Place area to the treatment plant. The second pipeline phase, which has not yet been funded, is expected to cost nearly $60 million.

DiFonzo said city officials will be seeking funding for the second phase during this week’s PACE reception in Annapolis. Officials from the Maryland Department of the Environment will be present at PACE as well.

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