Getting Control

The Water Services Department in Kansas City deploys more than 300 green stormwater initiatives in a citywide effort to help curtail CSOs

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An ambitious pilot project using green solutions in Kansas City, Mo., is believed to be the largest of its kind for combined sewer overflow control undertaken in the United States and overseen by a Federal consent decree.


The Middle Blue River Basin Green Solutions Pilot Project encompasses more than 300 green solutions within 100 urban acres. It represents one component of the city’s commitment to use green solutions to control runoff as part of the Overflow Control Plan submitted to the U.S. EPA and the Missouri Department of Natural Resources in January 2009.


Major water-quality studies by the United States Geological Survey (USGS) and work with eight basin engineers have paved the way for the city’s Water Services Department and the program management team from Burns & McDonnell, headquartered in Kansas City. Terry Leeds, overflow control program manager and stormwater utility manager, has led the city efforts since July 2005.

The department kicked off its first CSO control design in September 2009. The two-pronged attack involved rehabilitating 3.5 miles of combined sewer within the pilot area, and constructing green solutions in an initiative expected to take two years.


Getting there

According to a 2008 report from the Black & Veatch Corp. engineering, consulting and construction firm, the city has made great progress in stormwater management and natural resource protection. Efforts began in 1996, when the USGS studied small urban streams in the combined sewer area to define water quality based on bacteria levels.


During rain events, research showed that 40 percent of the bacteria came from human waste, 30 percent from animal waste, and 30 percent from other pollutants. “We learned that CSOs were only one part of the problem,” says Leeds. “Just separating our combined service sewers wasn’t going to do it. To really improve water quality, we needed a watershed management plan.”


The combined sewer area has 90 structures that contain some of the sewage and prevent it from reaching streams during low flows. From 2006 to 2008, Water Services investigated the condition of the 75-year-old combined sewer system in the pilot project area to discover what really was under the ground.


“The pipes range from clay tile to rock structures and some concrete sewers,” says Leeds. “Diameters vary from 8 to 48 inches to irregular-shaped box culverts.” Most lines under the streets were in decent condition. Crews found the worst degradation — collapsed pipe and infiltration and root intrusion at joints — where the clay tile traversed backyards.


“We’re replacing some of the pipe in those areas,” says Leeds. “We’ll also line the pipes under the streets as a precaution. After the green solutions are installed, we don’t want to dig them up to fix leaking sewers.”


Besides televising lines, crews did smoke tests, inspected manholes, installed flowmeters, and created survey data on the infrastructure, including the location of sidewalks and curbs. “We have a GIS, but it’s based on old, hand-drawn maps that were digitized,” says Leeds. “Their accuracy isn’t always the greatest.


“A couple of manholes in the project area were never dug up because they are in backyards. This year, we will rehabilitate most of the abandoned systems and reroute some of the retrofit. We also will line or rehabilitate most of the laterals up to the property line.”


Modeling the future

The basin engineers and Burns & McDonnell modeled the combined sewer system, showing the water sources and volumes. They then developed an overflow control plan that will reduce CSOs from more than three dozen to about half a dozen per year in the project area.


“It’s too expensive to separate all the combined sewers in the city, so we developed different overflow limits for each area,” says Leeds. “The cost of controlling overflows in the combined sewer area is $1.4 billion.”


Running parallel to the overflow control program is the KC-One Project, the city’s stormwater management plan. Water Services identified 35 watersheds within Kansas City, then developed master plans for them. KC-One combines those plans into one comprehensive plan. The cost is $2.1 billion for 750 stormwater projects, mostly driven by the need to correct undersized pipes.


A 1 percent sales tax funds most of the city’s capital projects. Stormwater maintenance and engineering is funded by a stormwater fee of 50 cents per 500 square feet of runoff surface. The average fee for residential property is $3 per month.


“Our stormwater fee brings in $10 million per year,” says Leeds. “That’s not enough to maintain what we have. If we’re going to provide consistent funding for stormwater projects, we’ll need more dollars.


“Some models indicate that we’ll need $10 per month from residential properties. That will make homeowners scream, but it also will be an incentive for them to do something to reduce the fee, such as using rain gardens or rain barrels.”


In 2005, Water Services and various city and county executives begin the 10,000 Rain Gardens community outreach program. KC-One managed it for the first year, then gave it to the city’s Overflow Control Plan. The program provided homeowner-based information and professional-level training and certification, bringing the enormity of the stormwater challenge down to a personal scale.


“We never knew how many residents built rain gardens or installed rain barrels,” says Leeds. “However, the program raised people’s awareness about the impact stormwater runoff has on the environment. Before the program, most citizens thought of stormwater as a flooding issue. Now, they understand the water-quality aspect, too.”


Flood control

Another component of KC-One identifies flood-control projects. Water Services has worked with the U.S. Army Corps of Engineers for more than 20 years to deepen and widen channels and to build levies and concrete flood walls. This work will probably continue for another 15 or 20 years.


A major boon to flood control is a stream setback ordinance that took effect in February 2010. It prohibits further development in floodplains. To deal with the more than 1,000 existing structures in those areas, KC-One recommends a voluntary buyout, but provides no funding.


“We’re analyzing three avenues, all under long-range planning,” says Leeds. “First, owners would sell the property to the city, and we would tear down the structures. Second, owners would be able to live there as long as they pleased, but they could sell only to the city. Third, we would build a levy or flood wall to protect the property if the owner’s investment were substantial and the cost-benefit ratio were high enough.”


While there are hundreds of privately maintained stormwater detention ponds, only five belong to the city. However, when the pilot project area is completed, the city will own more than 300 green solutions involving rain gardens, bioretention swales, infiltration galleries, permeable pavement and street trees.


Power of trees

Trees have many benefits, says Mark Govea, landscape architect with the city. The leaves, roots and bark sequester carbon and hold and absorb substantial amounts of stormwater. “The pilot project area already has many street trees, but we’re filling in the gaps by planting more,” he says. “We’re working with the city Forestry Department on what types of trees to plant.”


The annual leaf drop raises the possibility of clogging the green additions. “We don’t know what it will take to maintain these structures or the cost,” says Leeds. “We’re analyzing whether we should maintain them or create networks to do the work.”


The city now collects brush and vegetation in spring and fall. Homeowners may put out 30 biodegradable bags or take the material to composting sites. “We want to encourage people to build compost piles in their yards,” says Francis Reddy, senior registered engineer with the city. “However, compost piles have some stigma attached to them because they can attract undesirable wildlife.”


Another concern is how salting streets in winter will affect the green solutions. “Time will tell which plants are more salt resistant,” says Reddy. “We can overcome this issue. We just want to do it correctly.”


Rain gardens in the pilot project are slated for public right-of-ways and easements. While Water Services will maintain them in those areas, Leeds hopes that responsibility will eventually shift to property owners in other parts of the city.


“For green solutions to really work, you need a lot of them,” says Leeds. “The city has far more private property than public. Over time, we hope to create an appetite and appreciation for green solutions that will motivate property owners to adopt rain gardens, disconnect downspouts and use rain barrels, or build rain gardens on their sites.”


After the pilot project is completed in winter 2011, the city will work with the EPA Office of Research and Development to monitor the program’s effectiveness in reducing stormwater runoff. The information will guide the design of future green solutions in Kansas City.


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