C. Falls says costs of repairing sewer plant could reach $100,000
A sewage leak at the Columbia Falls wastewater treatment plant, which put the city in violation of its state permit and at jeopardy of substantial fines if not fixed by April 15, could cost $100,000 to remedy.
City Manager Bill Shaw's early estimates had pegged the cost as high as $150,000, depending on what crews find. But he said $100,000 was a more-likely ceiling on the expense.
The expense had been planned since a recent facilities study by engineer Craig Caprara of HDR Engineering in Missoula outlined an overall $3.6 million upgrade, which the city expects to carry out in 2008.
About $40,000 of Shaw's projected $100,000 will pay for installing a new liner on the 550,000-gallon aeration basin.
Cracks in that basin have been allowing between 100,000 and 120,000 gallons a day to seep untreated into the ground at the plant along the Flathead River, making the repairs urgent. The basin was built in 1972 by shooting gunite, a cement mixture, into metal mesh forming the 14-foot-deep V-shaped basin floor and walls.
City Council members Monday night declared an emergency, allowing the city to contract for the repairs without a time-consuming bidding process.
The city will apply $15,000 to the rental of pumps and pipes that will reroute sewage to the current sludge storage basin, which will be used as a temporary aeration basin. Effluent then will be routed through the rest of the plant's treatment channels.
In addition, the city is paying a $250-a-trip tipping fee as it drains the sludge storage basin and hauls it to the county landfill. Sewer and Water Superintendent Gary Root said the trucks can haul as many as two loads a day.
Alternately, some of the effluent is being applied to farmland on a trial basis. But with the trucks sinking into soft spring soil, land application is limited to early mornings when the ground is more firm. To accommodate the required continuous pumping, sludge must be hauled to the landfill, as well.
Root and sewer plant chief operator Hugh Robertson discovered the discrepancy between influent and effluent after a new flowmeter was installed in late December. They reported the leak Feb. 6 to the Department of Environmental Quality.
The department sent an inspector to the plant Feb. 8, then followed up with a Feb. 28 letter that laid out an April 15 deadline to correct the violations.
On Tuesday morning, Robertson said the sludge storage basin was being emptied, moving up the semi-annual pumping that had been scheduled for later in the season.
Root said pumping that basin will take two weeks so the aeration basin can be emptied into it. Two days after that starts, the aeration basin will be empty - meeting the April 15 deadline for stopping the leak.
The aeration basin then will be ready for a new geotextile layer over the concrete floor, topped by a PVC liner. At the same time, new piping and other retrofits will be installed to convert it to an equalization basin during the overall plant upgrade in two years. As an equalization basin, it will provide redundancy for a proposed new aeration basin.
Root said the aeration basin is expected to be out of service about six weeks, then long enough to test that relining work.
He sent a March 9 letter to the state Water Protection Bureau, outlining the planned remedy pending the City Council's action Monday night.
The council also agreed to hold an April 17 public hearing on two related issues: Gathering public comment on the sewer plant upgrades and other community needs, a preliminary step to applying for Treasure State Endowment Program grants; and gathering comment on a proposed rate increase that would add $1 a month this year to the $4.35 sewer base rate for each residential customer, $2 a month in 2007, and $3 a month if needed in 2008.
Letters notifying water and sewer customers about the hearing should be in the mail by April 3.