Private system’s leaky and narrow pipes targeted to reduce utility costs


There are an estimated 10 miles of private sewer lines in Columbia that connect to the city’s treatment system, and 70 percent of those lines are in the Old Southwest.

Many of the homes in the neighborhood, situated south of Broadway between Providence Road and West Boulevard, were built in the 1930s and 1940s, and many homeowners hooked their sewer line onto their neighbors’ lines instead of connecting to the city sewer system.

Steve Hunt, manager of environmental services for the city, said these private lines were probably once connected to lagoons for treatment.

These days, the private lines connect to the city system. Nonetheless, they continue to cause problems for some homeowners.

A $77 million bond issue on the April 8 ballot for the city sewer system includes $2 million to eliminate private common collectors and $2 million to rehabilitate lines that are part of the public system.

City sewer lines are required to be at least 8 inches in diameter and connected to a manhole for stability and access for maintenance. In contrast, many of the private lines in the Old Southwest are 4 inches in diameter and connected with brackets that don’t always afford the best connections. Many of the old clay pipes leak and have a tendency to collapse.

Jerry Hall, general manager of Master Tech plumbing, said many of the old pipes are joined in 3-foot sections.

“As time goes by, the ground shifts and moves the pipes,” Hall said. “Water seeps out, and tree roots grow toward the water. Everything builds up through there.”

Once they’re removed, the roots grow back stronger and can move the pipe more than the shifting ground, Hall said.

These problems manifest themselves in basement backups and the surfacing of sewage in yards. Residents can go to the city and apply for a petition to get the problem fixed.

The Columbia City Council on Monday approved a policy that means homeowners are no longer responsible for shouldering the cost of replacing private collector lines. And instead of focusing on replacing large service areas, like blocks at a time, the city will only replace the portion needing immediate attention.

While the policy change is separate from the bond issue, Hunt said, the new approach means that funds from the bond issue would be used more efficiently. When residents are required to pay for the work, it takes more time for the city to get approval. Hunt said the city still hasn’t used all the money included in a 2003 bond issue for private collectors, but he is unsure how much.

The number of private common collectors the city would be able to bring up to city standards over the next five years depends on many factors, Hunt said, including the depth of the sewer or whether it extends under a street or through someone’s backyard.

“I’m certain to say that the money will not fully fund elimination of all private common collectors,” Hunt said.

Hunt said he hopes to eventually bring all identified private common collector lines up to city standards.

“Benefits will be citywide,” Hunt said. That’s because the expense of filtering out solids from water that infiltrates the sewer system through the old lines is borne by all utility customers.

“A lot of these pipes have been in the ground for 60 years,” he said. “They leak and let a lot of groundwater into the city system.”

The $2 million included in the bond issue is for rehabilitating some of the 625 miles of city-maintained sewer lines and manholes, which the city does to keep sewage from seeping out of the lines and groundwater from entering the system. Essentially, the rehabilitation process creates a new pipe, without requiring that the old one be removed, using “cured in-place pipe” technology.

The process uses a fiber material sleeve coated in a polyester resin mixture. Once the feltlike sleeve has absorbed the material, it is inserted through a manhole into an already existing pipe. Steam is then blown into the pipe, pushing the material outward to encase the inside of the pipe close to one-eighth of an inch thick.

The 2003 bond issue, which totaled $18.5 million, also included $2 million for maintenance of public sewer lines, work that totals about $500,000 a year.

“The idea of public sewer is to protect the public health,” Hunt said. “We want to get situations fixed before people have public health problems.”