COLUMBIA — City staff put a $20 million price tag on increasing downtown utility capacity Wednesday evening.
Sewer and electric system expansions are the two improvements most needed to accommodate additional population downtown, according to a presentation given by city staff to members of the Downtown Columbia Leadership Council Infrastructure Subcommittee.
Columbia Water and Light Department Director Tad Johnsen, Public Works Director John Glascock and Deputy City Manager Tony St. Romaine provided details of the city's current sewer and electric utility capacity, and each department head explained the cost of improvements to his respective utility.
Funding a four-piece replacement of the Flat Branch sewer system would cost $6.75 million, and the cost of repairing the roads torn up from replacing pipes would be about $3 million, Glascock said.
The Flat Branch sewer system features one main pipeline that runs under University Village Apartments and below the MKT Nature and Fitness Trail. That main line is fed from three other lines that span downtown. Those three lines receive flow from hundreds of smaller pipes below streets.
According to a chart from the meeting, the maximum capacity of the main pipe is 3,800 gallons per minute. Existing daily flow is well below the pipe's maximum capacity.
Glascock said the city likes to operate a little below maximum capacity.
"Ideally, peak flow is no more than 80 percent of the capacity of the pipe," he said. "We don't like anymore than that in the pipe. That includes inflow and infiltration ... or storm water getting into the pipe. Yesterday, it was flowing about that. This morning it wasn't at capacity; it was above capacity, actually. It was up in the manhole."
According to the Missouri Climate Center's website, Columbia experienced about 1.5 inches of rain Wednesday, which caused the main pipe to overflow.
The flow chart at the meeting showed an inch of rain brings peak flow to about 4,000 gallons per minute and causes overflow.
The estimated capacity of already approved developments is more than 4,000 gallons per minute, according to the chart. Most of that capacity will come from the around 600 beds of student housing approved March 19 by the Columbia City Council, Glascock said.
The 351-bed Collegiate Housing Partners and 256-bed Opus Development Co. projects are slated to open in August 2015.
Collegiate Housing Partners will pay $150,000 of the $450,000 cost to replace the smallest of the three lines feeding the main Flat Branch trunk line. Another student housing developer, American Campus Communities, had agreed to pay the remaining $300,000 cost of the line, but the proposed 718-bed project was tabled until May by the council.
St. Romaine said the city will pay the difference and could perhaps be reimbursed by a developer in the future.
The four-piece Flat Branch sewer project could be done one piece at a time but, replacing the main line (shown as Project No. 1 on the presentation by city staff) would need to come first, Glascock said.
"All of downtown flows through that pipe," he said.
Johnsen said current downtown electric capacity is about 14 megawatts. The current maximum load is between 12 and 13 megawatts.
"We're comfortable with peaking fairly close to maximum," he said.
Johnsen said Opus Development's and Collegiate Housing Partners' projects would need about 4.5 megawatts total. That capacity would come from the arrival of 5 megawatts from the Rebel Hill substation.
Any additional downtown development will require about 12 more megawatts, which would come from constructing two feeder lines from the Hinkson Creek substation. Constructing the two feeder lines would cost $10 million and would need to be funded by a bond issue, which would be paid for by funds from electric rates, he said.
Johnsen said the water utility system downtown was adequate, and the only concern was having enough flow to provide the fire department with enough water to work their hoses. The cost of water improvements is usually paid by developers.
Glascock said a study detailing the cost of storm sewer improvements would become public sometime this summer. Until that study comes out, it's unclear how much work will need to be done.
Subcommittee members' questions and reaction
Throughout the meeting, members of the subcommittee asked St. Romaine, Glascock and Johnsen if the infrastructure issues facing the city could have been avoided.
Glascock said his department had been monitoring the flow in the downtown sewers since the first downtown student housing project was completed three years ago. If there had been no downtown development, he didn't believe the city would be facing this sewer issue.
He also said the city's sanitary and storm sewers are at least fifty years old.
According to St. Romaine, the city prepared for the student housing projects that were built south of MU's campus, but it wasn't anticipating residential use in downtown.
"I don't know how anybody's crystal ball could've predicted that," he said.
Downtown Leadership Council Chairman Brent Gardner said city staff had provided enough information for the subcommittee to process and begin to define infrastructure at its next meeting, which is at 5 p.m. Wednesday.
The subcommittee was waiting on input from the council to determine how much action it should take on the infrastructure issue.
Downtown leadership wrote a letter to the council asking for direction on the issue, which the council will discuss at its meeting Monday.
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