CSO control revitalizes stretch of the Mississippi
Earlier this year, the cities of St. Paul, South St. Paul and Minneapolis and various organizations celebrated the substantial completion of a 10-year, $331 million sewer separation program for Combined Sewer Overflow (CSO) control. The program helped to clean up the 72-mile stretch of the Mississippi River that flows through the Minneapolis-St. Paul area.
Planning for the comprehensive CSO control program began in when governments and the public recognized that a regional solution was needed to solve ongoing water quality problems in the Mississippi River. The Metropolitan Council Environmental Services, the municipal sanitary sewer district serving the metro area, and the Metropolitan Council, the regional planning authority, prepared a draft plan for mitigating the impacts of CSOs in Minneapolis, South St. Paul and St. Paul. Final recommendations from the study included construction of new regional sanitary interceptors to ensure capacity and the acceleration of sewer separation projects underway in all three cities.
In 1984, St. Paul engineers estimated that an average of 4.6 billion gallons of untreated sewage and stormwater from the metro area overflowed into the Mississippi River annually, with discharges occurring an average of once every three days. St. Paul had begun separating its combined sewers in 1958 as part of ongoing capital improvement projects, but according to the construction schedule, total sewer separation would not be completed until 2025.
The public demanded a faster fix, and in 1984 a plan to complete the remaining CSO control work in 10 years was announced.
The Minnesota Legislature adopted the accelerated schedule in 1985 and approved new state CSO funding and a statutory 10-year deadline. By this time, St. Paul had already separated about 64 percent of the area originally served by combined sewers. The deadline meant that the remaining work had to be completed by 1995.
St. Paul’s Comprehensive Sewer Plan for stormwater management, prepared in 1984, recommended $172 million worth of projects to separate combined sewers to meet stormwater drainage needs.
Prior to construction, the existing sanitary sewers in project areas were televised to identify those sections in need of repair, so that they could be repaired at the same time the new storm sewers were being built.
Financing for the program initially was split equally between St. Paul, the state and the U.S. Environmental Protection Agency. By 1991, however, the federal grants program ended, forcing the other partners to reassess funding for the program.
The Minnesota Legislature was faced with a hard choice in 1990. Five years earlier, it had set a statutory deadline for CSO elimination, based on a joint federal-state-city funding arrangement. Fortunately, the legislature decided to increase the state’s funding to cover one-half of the federal shortfall, and St. Paul picked up the other half.
The sewer separation program required numerous utility offsets and relocations. Thus, the sewer separation program gave local utilities a chance to upgrade facilities at a lower cost than usual, since many streets were already being restored or repaved. On many projects, locally based Northern States Power replaced its gas lines and services and installed outside meters where new services were constructed. Weekly coordination meetings were held on the larger projects.
In carrying out the sewer separation program, the city:
* installed 189 miles of storm sewers and 11.9 miles of sanitary sewers
* paved 168 miles of oiled streets. While designing the sewer program, the city had realized that trench restoration being done with the sewer work could include paving entire streets at two-thirds the normal cost;
* installed 8,200 new street lights, more than 8,200 handicapped-accessible ramps in sidewalks and 336 miles of curbing along city streets;
* planted more than 11,000 trees;
* replaced more than 3,500 lead water services with copper pipe, and replaced 26 miles of water main; and
* disconnected rainleaders at 21,900 residential properties.
Additionally, 238 miles of gas mains were installed and 25,000 gas services were upgraded or replaced by the local power utility.
Dealing with rainleaders was important, since St. Paul estimated that at as much as 20 percent of its CSO volume was cause, by private drains and rainleaders connected to the sanitary sewer system. In 1986, the city began a two-year voluntary rainleader disconnect program focusing on residential property and including the following elements:
* a rebate of $40 to homeowners who voluntarily disconnected;
* public service announcements on cable and local broadcast stations;
* presentations to neighborhood groups by city staff;
* program posters in bus shelters;
* free evening classes for homeowners on the disconnect program;
* hiring of 23 chronically unemployed individuals to disconnect rainleaders for around 900 low-income homeowners; and
* a program developed by one neighborhood district that hired college students to disconnect rainleaders and lent tools to homeowners who did their own disconnections.
Nearly all properties are now disconnected. The remaining connected rainleaders are primarily at industrial and commercial sites, and the city is currently evaluating options for financing to assist owners of these properties.
Community outreach was also an important part of the program. For example, in 1993, St. Paul was working on a major separation project on the east side of the city, where a large number of residents are immigrants from Southeast Asia. To explain the project and its inconvenience, noise and dust, an outreach campaign was conducted in the immigrants, native language.
For generations, residents had avoided the Mississippi River flowing through the Twin Cities area. After all, they had hundreds of other attractive lakes and rivers to use in Minnesota, whose license tags proclaim it the “Land of 10,000 Lakes.”
The sewer separation program has begun to change this situation for the better. For example, as fecal bacteria levels in the river have dropped significantly, the pollution-sensitive Hexagenia mayfly has returned to the river after a 30-year absence, and bald eagles have also returned. Fish populations have recovered from three species to more than 25 species.
In addition, the number of boat slips on the river has nearly doubled. Plans for planting 25,000 trees, shrubs and wildflowers in the river valley are also in the works.
The public’s perception of the river as a cleaner and more desirable area for recreation has been demonstrated repeatedly in the past few years. Through the CSO control program, the river has become more of a focus with new parkways and parks, a marina and special events.