Similar to many communities across the nation, Kansas City, Missouri, is faced with meeting federal requirements to improve water quality by reducing the frequency and volume of combined sewer overflows. Under the umbrella of the city’s Overflow Control Plan, Kansas City’s Smart Sewer Program is integrating green stormwater infrastructure (GSI) as part of its Smart Sewer program to reduce combined sewer overflows.
These green infrastructure improvements have the potential to provide multiple benefits to the city’s neighborhoods while reducing combined sewer overflows. By defining a path and developing the tools to holistically manage frequent rainfall events, the city can better achieve regulatory objectives, provide benefits for the community and cost-effectively improve the quality of water in the local streams. Critical to effectively implementing GSI for any community is the strategy and planning behind it. Communities looking to meet federal requirements while improving water quality can look to Kansas City as an example of how GSI implementation works and the benefits a community can realize.
GSI Projects With Multiple Benefits
An initial step is piloting various scales of GSI projects, which are being connected to the surrounding land use and integrated with other city projects and community initiatives. Since the first project, GSI has been constructed on a neighborhood scale, integrating with community parks, and on a centralized scale, providing both water quantity and quality benefits. Recent GSI design efforts are further piloting these scales within a primarily industrial area, in addition to an urban revitalization area with historical significance. Multiple benefits have resulted from these pilots, including comprehensive infrastructure projects focused on larger community benefits, not just reduced combined sewer overflow.
GSI Maintenance and Strengthening the Community
For the maintenance of GSI, both city crews and a local nonprofit that is focused on workforce development are being used. To supplement this, the National Green Infrastructure Certification Program is used to train a green workforce on GSI maintenance tasks. The local nonprofit organization, Bridging the Gap, hires and trains green stewards to perform both maintenance and monitoring tasks as part of a city-funded program. The Green Stewards program has two goals. The first goal is the routine maintenance of the GSI sites, which are met with careful scheduling of site maintenance, dedicated physical work and the recording of site activity. The second goal is the development of the stewards’ skills in GSI and landscape maintenance to qualify them for successful employment. In March 2018, the green stewards began maintenance activities across approximately 200 GSI sites.
GSI Intelligent Management to Optimize Existing Infrastructure
Continuous monitoring and adaptive control (CMAC) is an intelligent management strategy that integrates the weather forecast with stormwater infrastructure operations to optimize the outflow hydrograph from GSI. This adaptive strategy allows more water to be treated, without compromising flood control or erosion mitigation benefits. The proprietary CMAC software uses a control algorithm to continuously and autonomously modulate the discharge valve installed on the outlet structure based on the pond water level and the precipitation forecast. Kansas City was able to put this technology to the test with two major rain events in 2017, and additional retrofit installations are undergoing evaluation.
Planning for the Next Generation of GSI
There are three main factors that create the basis for future GSI projects in Kansas City, which can be implemented in other communities looking to meet similar goals. This includes reducing stormwater inflow into the collection system for smaller frequent rainfall events, integrated public improvement solutions that increase public benefits at a lower overall cost and stimulating investment in the community. Opportunities to define policy and evaluate GSI integration using a watershed-based approach are a major focus. Properly planned, designed and implemented GSI projects reduce stormwater runoff where it is generated, while complementing existing neighborhood characteristics. In addition, redefining and connecting natural flow paths improve stormwater connectivity within the urban landscape, addressing more frequently flooded areas.
A great deal of thought, planning and understanding goes into meeting federal requirements and improving local surface water quality that the entire community can enjoy. It’s important to take the opportunity to learn from others when it comes to approach, technique and design for GSI implementation.
Water utilities and residents work together to envision projects that invest in both green infrastructure and the neighborhood.