Columbia prepares sewer system expansion

The city sewer system was been expanding for more than 100 years and now serves nearly 110,000 customers with 600 miles of sewer lines, with an average flow of 15 million gallons per day. The lines are accessed by about 16,000 manholes. The wastewater treatment plant was built in 1983 and there are 23 pump stations, four of which are main pumping stations.

The sewer system master plan projects that the wastewater flow will increase to 28 million gallons per day by 2030, when the customer base will have grown to 175,000. The plan calls for an upgrade of the main sewer treatment plant and the installation of three pump stations in the Little Bonne Femme Watershed – an upper station in 2014, a middle station by 2015 and a second Clear Creek pump station by 2030.

The plan recommends installation of approximately 146,000 feet of relief sewers by 2010, 92,000 feet by 2020 and 148,000 by 2030. The first priority would be the lower Hinkson and southwest sub-watersheds, which currently experience backups on an annual basis.

The master plan recommends installation of about 57,000 feet of sewer extension by the year 2010, 94,000 feet by 2020 and 112,000 feet by 2030.
The average monthly bill for residential sewer service is $11.22, and the connection fee is $500. The Boone County Regional Sewer District’s rate is $21.73 a month.

The master plan recommends paying for the expansion with a combination of connection fee and service rate increases to keep the annual rate increases below 10 percent. The plan proposes that the city increase the $500 connection fee by 25 percent increments in fiscal 2007, 2009 and 2011 and by 50 percent in 2013. The plan said the expansion would require rate increases of 6 percent in 2009, 7 percent in 2010 and 8 percent from 2011 through 2014. Beyond 2014, annual rate increases of 2-3 percent would be required.