Multi-phase improvement project reduces storm water flooding and sewer backup
Brookside—a neighborhood in the southern part of Kansas City, Mo.,—was planned, designed and built in the 1920s and was home to the city’s first suburban shopping area. Designed to serve the automobile, it featured specialty, grocery and drug stores, and medical offices. It boasted the first special community center as well as the first south side police and fire stations.
However, unlike other areas that were being developed in Kansas City at the time, Brookside was developed with separate sanitary and storm sewers. The oldest parts of Kansas City, consisting of approximately 56 sq miles, were developed utilizing combined sewers.
As areas around Brookside continued to develop and expand, additions were built on houses, more driveways and patios were paved and, subsequently, runoff increased. As time went by, interconnections between the sewer and storm systems were installed to reduce the flooding and basement backups that were occurring. Interconnections were never part of the original design of the storm drainage or sanitary sewer systems. Although these interconnections addressed individual homeowners’ sewage and drainage concerns, they often created larger problems in downstream areas.
Flooding occurs because the existing system cannot handle the amount of water. Sometimes when it rains, sanitary sewage backs up into the basements of some homes and businesses. These backups occur because storm drains are hooked into the sanitary sewers rather than the storm sewer system or because the storm and sanitary sewers have been interconnected. The reason these larger problems are created is because sanitary sewers were not designed to carry both storm water and sewage. The practice of installing such interconnections does not comply with today’s engineering and plumbing codes and standards. In fact, the practice was made illegal by the Clean Water Act in 1987.
In October 1998, a deluge of rain hit Kansas City, flooding streets, overtopping bridges and backing up sewers. Following that event, a study of the existing system was initiated, including gathering information from citizens, merchants and community groups about problems, concerns and expectations through questionnaires and public meetings. The City Council and the Kansas City, Missouri, Water Services Department began to develop a Brookside-specific program to address the storm water and sanitary sewer issues through public improvements and citizen action. The department recognized that the program would not eliminate all flooding and sewage backups, but it should reduce the severity and damage caused by rain events.
Public meetings were held between November 1998 and October 2000 to gather input, discuss proposed improvements and present time schedules to residents. In addition, meetings were held to discuss smoke testing that was conducted in the neighborhood. In January 2005, the department conducted smoke testing throughout the Brookside neighborhood to identify public- and private-sector sanitary sewer defects. The public defects were investigated. Direct storm water connections that were determined to be public have now been identified, and plans have been developed to remove them from the system.
Public meetings were held to present the results of the investigations and notify property owners of any defects on their property. Defects included cracked private sewer lines, downspout connections and other inappropriate connections. Residents were provided with information on how to make the repairs to remove the inflow and infiltration from the sanitary sewer system.
Plenty to improve
The Brookside Watershed Improvement Program is a public investment of more than $50 million over an anticipated 11-year period with phased projects to construct improvements to the storm drainage and sanitary sewer systems. Improvements include disconnection of storm and sanitary sewers, new storm inlets, more than 13 miles of improved conveyance via new pipes and box culverts and storm pipe rehabilitation ranging in size from 15-in. diam. to 12-ft by 10-ft box culverts. Approximately 25% of the project is funded by a city sales tax through the Public Improvement Advisory Committee (PIAC) and the remainder by voter-approved revenue bonds.
To reduce flooding and sewage back-ups, the following improvements are being done:
- Replace, modify and add catch basins in the streets to collect storm water runoff;
- Repair and replace existing system pipes;
- Install new pipes to expand the capacity of the systems; and
- Disconnect the storm drainage and sanitary sewer systems from each other within the project limits.
The program was divided into five phases to match available funding.
Phase 1: Local repairs (complete). Phase 1 was basically “quick wins.” Aging catch basins were replaced to increase storm water runoff capture. Storm drainage and sanitary sewer systems were disconnected from each other. A cured-in-place pipe lining was installed in several locations in the aging storm sewer pipes, and improvements were made to sanitary sewer pipes to increase capacity and to prevent future pipe collapses. The approximate construction cost of Phase 1 was $500,000.
Phase 2: Huntington relief sewers (complete). New storm drainage box culverts and piping were installed along with new curb inlets to both replace aging inlets and to increase the amount of storm water captured. A new sanitary sewer also was installed parallel to the new storm system. The new systems replace old systems that are located in backyards and under garages. Both the existing and new pipes were used, expanding the carrying capacity of the systems. The approximate construction cost of Phase 2 was $3.1 million.
Phase 3: Brookside neighborhood improvements (designed). Catch basins will be replaced and added in streets to improve storm water runoff capture. Existing storm drainage piping also will be rehabilitated, replaced and supplemented, along with some of the sanitary system in the area. The approximate construction cost of Phase 3 is estimated to be $10.2 million.
Phase 4: Crestwood neighborhood improvements (under construction). Catch basins are being replaced and added in streets to improve storm water capture.
Existing storm drainage piping also will be rehabilitated, replaced and supplemented, along with portions of the sanitary system in the area. The approximate construction cost of Phase 4 is estimated to be $6.5 million.
Phase 5: Brookside Interceptor (design stage). Phase 5, the Brookside Interceptor, is the backbone portion of the Brookside Watershed area storm drainage system. The current plans are to supplement the existing storm drainage interceptor system with a new parallel system to increase carrying capacity. Additionally, the plan is to eliminate interconnections to separate the storm and sanitary systems along the project alignment. The approximate construction cost is estimated to be $31 million.
Recipe for success
The project thus far has had its challenges, including easement encroachments, easement access, yard improvements, existing utility relocations and road improvements. The Bookside neighborhood also is known for its numerous large trees. Extra care has been taken to minimize the number of trees removed or damaged by the project.
During this project, the Water Services Department also has worked with the city’s Parks and Public Works Departments to make minor improvements to streets and walkways where it was advantageous.
This project’s success is a direct result of how the City Council identified funding sources in conjunction with the Water Services Department’s phased approach to use available funds along with an extensive public outreach program to benefit a neighborhood and improve the overall quality of life.