Clean and green
Public desire for open space that includes clean streams and lakes, along with more stringent federal environmental regulations, have prompted many communities to adopt environmentally friendly stormwater management methods. Rather than using the traditional practices of enclosing channels in pipes and draining wetlands, which often permanently alter the ecosystem and destroy habitats, alternative methods mimic natural landscape features to improve water quality and waterside environments.
Traditional stormwater practices typically decrease water quality because they do not include a natural ecosystem to assimilate pollutants. In addition, they tend to shorten flow paths, creating higher peak flows. Many communities face flooding issues as a result.
Environmentally friendly approaches to stormwater management are designed to resemble the natural functions that support habitats and protect water quality. In addition, they slow water flow and often detain it, which results in lower peak flows and less flooding.
Santa Monica, Calif., has adopted new stormwater management methods to improve its water quality. Situated on the Pacific Coast north of Los Angeles, the city is surrounded on all sides by other cities or by Santa Monica Bay, which collects all of the city’s stormwater runoff. To protect the water quality of the bay, as well as the beauty of area beaches, the city has begun building additional stormwater treatment facilities to remove pollutants — such as organic compounds, metals and trash — from runoff before it reaches the beach. Because space is limited, the city is building the facilities underground.
One recently completed facility was built under a parking lot in a park owned and operated by Los Angeles. The Westside Water Quality Improvement Project, which treats stormwater runoff from a large portion of Santa Monica, was designed with no moving parts, chemical additives or electrical power requirements. “Urban runoff pollution is a major problem for our coastal waters, and this project is one big step in a long and continual process to ensure cleaner water and a healthier coastline, and to safeguard life,” says Santa Monica Senior Environmental Analyst Neal Shapiro.
The system is designed to remove chemicals, such as pesticides, as well as organic compounds from automobile emissions and other sources from stormwater runoff. While not its primary purpose, the facility may collect chemicals from accidental spills, preventing them from reaching the bay. Santa Monica currently is identifying other sites for similar treatment systems.
While Lenexa, Kan., is not as confined as Santa Monica and other cities, it has plenty of stormwater and must plan for its proper management now and in the future. In the late 1990s, Lenexa officials began adopting more stringent stormwater design criteria, a stream buffer ordinance, and erosion and sediment control ordinances. To raise money to pay for better stormwater management, the city created a stormwater utility and instituted a capital development charge, and residents approved a sales tax to fund construction of new treatment facilities that also could be used as recreational areas.
The city’s stormwater quality efforts are primarily designed to manage nutrients and sediment — the main pollutants from residential areas that comprise the majority of the city’s landscape. Nutrients attach to the sediment, and the sediment clogs streams and chokes out aquatic vegetation.
Lenexa is creating multi-use facilities that manage stormwater, prevent floods, improve water quality and provide recreational outlets for residents. The city displays information about watershed protection on signs throughout the park-like areas and uses environmentally friendly construction materials where possible.
Taking a holistic view
In Kansas City, Mo., as in many large cities, outdated stormwater infrastructure has inadequate capacity to carry runoff from large storms and to adequately treat it to meet current standards. A large portion of the city’s stormwater infrastructure is in a combined sewer system that transports both stormwater and sewage. During heavy storms, increased runoff can cause overflows that discharge untreated sewage into area waterways.
To update the system and ensure it can handle future growth, local officials are reviewing the city’s entire stormwater management program, including physical components as well as administrative and financial management procedures, to identify areas for improvement. In the months ahead, they will update existing flood control plans to reflect a holistic approach to stormwater management that involves flood control, combined sewer overflow reduction, water quality management and natural resource protection.
As part of the effort, Mayor Kay Barnes kicked off a program in November 2005 to encourage residents to plant rain gardens, which are shallow basins or depressions foliated with native plants that have deep roots that help water infiltrate the soil. The mayor’s goal is for 10,000 rain gardens to be planted to demonstrate that if residents and businesses manage their own stormwater, peak flows to the city’s infrastructure will reduce — as will costs for infrastructure improvements — and water quality in local streams will improve. The program also is raising residents’ awareness of how their daily activities can affect stormwater runoff.
Nearby Mission Hills and Mission, Kan., also are addressing flooding issues, which have been caused by lack of regulations and upstream development that has generated more runoff. Mission Hills is an affluent community in the Kansas City metropolitan area in which residents frequently use public areas for walking, biking, jogging and relaxation. However, recent developments threaten to change the streamside corridors that residents have come to enjoy.
Development upstream of the city over the years has increased the amount of runoff channeled to area streams. Combined with aging stream channel walls and other infrastructure, the runoff is causing stream banks to fail, jeopardizing adjacent roads, water and gas mains, sanitary sewers, driveways and other property.
Rather than addressing each issue individually, city officials have begun studying the stream network in its entirety and searching for stormwater management practices that can improve large parts of the network at once. Numerous city staff as well as the planning commission, parks board and city council members are involved in the study. “This process has changed people’s opinions on how city government manages its streams,” says Mission Hills City Administrator Courtney Christensen. “Instead of more limited city government involvement, people feel it is imperative that the city protect our important natural resources.”
As a result of the study, city officials will develop stream protection guidelines for buffers, landscaping and channel walls. They also will address land disturbance issues, lawn chemical applications, impervious lot coverage, and develop educational materials for residents. The measures will stabilize runoff from impervious areas and will protect — and eventually improve — the stream corridors by setting back human intervention and activities from streams. The buffers also will filter pollutants from the runoff before it enters the waterways.
Mission, Kan., began changing its stormwater management practices approximately three years ago, when costly floods prompted the city to complete large-scale flood control improvements and to redevelop its downtown area. As the city continues making improvements, it is incorporating environmentally friendly practices and stream restoration projects where they are feasible. City leaders now are looking for methods to decrease runoff and improve water quality citywide.
The city is conducting a study funded by the U.S. Army Corps of Engineers to identify locations for new treatment facilities and stream restoration projects. The project will provide a plan for constructing facilities and stream restoration projects that will improve the environment and the water quality of area streams. In addition, the study includes the development of a geographic information system tool that will identify suitable locations for the projects based on land use, topography and stream connections. The tool will select appropriate projects based on those parameters and on the stream quality. From there, cost estimates for project construction will be developed, and improvements will be prioritized for construction.
The city is working with Kansas State University to monitor the effects of the improvements. It also is constructing demonstration projects that will be monitored for their effects on water quality and will be used to help educate residents about the importance of managing stormwater in an environmentally friendly way.
Like Santa Monica, Kansas City and Mission Hills, many communities throughout the country are embracing environmentally friendly stormwater management methods because of the ecosystem improvements and social benefits they provide. Such holistic and “green” approaches aim to ensure that the natural beauty that residents enjoy does not disappear in the future.
Donald Baker is the central region water resources practice leader, Les Lampe is the water resources global practice leader, and Laura Adams is a water resources engineer for Kansas City, Mo.-based Black & Veatch.