Building Green Infrastructure – Why it Matters that Contractors Know How to Construct Green Infrastructure

Background In the Kansas City region, over the last 20 years stormwater best management practices and green infrastructure have been designed based on criteria developed in the early 2000's. However, communities are having trouble successfully building (and maintaining) green infrastructure. Why? Here in the Kansas City metro, we have regional design criteria for stormwater infrastructure. We're no stranger to understanding the importance of 'stormwater knows no jurisdictional boundaries', as our region lays at the confluence of the Kansas and Missouri Rivers. Though we may not experience the water scarcity issues faced by other communities, we see the need for stormwater quantity and quality measures. The Kansas City Metropolitan Chapter of the American Public Works Association (APWA) periodically updates the regional design criteria for stormwater infrastructure, commonly referred to as APWA 5600. In cooperation with the Mid-America Regional Council (MARC), APWA published this region's first Manual of Best Management Practices for Stormwater Quality in 2003, commonly referred to as the BMP Manual. In 2006, APWA 5600 was updated, referencing the BMP Manual, but not requiring management of smaller storms with green infrastructure. In 2011, APWA 5600 was updated , defining 'Comprehensive Control' as the default strategy for stormwater management, which requires control of the water quality event. However, the updated design criteria neglected to state how the water quality event should be 'controlled', only referencing the BMP Manual. Then, in October 2012, MARC and APWA released the latest BMP Manual. What are the problems? Implementation ' Some communities have adopted outdated version of APWA 5600, the BMP Manual, or both. Some communities have adopted APWA 5600 or the BMP Manual, but not both. Some communities have adopted other requirements that are barriers to implementing green infrastructure (e.g. Landscaping and screening requirements for the area between back of curb and sidewalk to be turf). Design ' Outdated design criteria for green infrastructure. The BMP Manual was last updated in 2012. A lot has been learned about green infrastructure, specifically designing with constructability and maintenance in mind. Ever-changing nomenclature for various types and components of green infrastructure has led to confusion on how green infrastructure should be designed. Construction ' Historically, construction of green infrastructure has been difficult due to lack of experienced contractors, available products, and materials. With the continued design and construction of green infrastructure over the past decade, resumes of local contractors have grown; however, inconsistency in details and specifications have left contractors confused on the 'right' way to build green infrastructure. Maintenance ' Just like sewer pipes, pumps, and treatment plants need maintenance, so does green infrastructure. Many of these sustainable systems are most susceptible to failure immediately following construction before vegetation has established. Without thoughtful maintenance procedures in places, green infrastructure is prone to failure before reaching its optimal performance. Monitoring ' The functional components for many types of green infrastructure are below grade out of sight, out of mind. Whether it be vegetated green infrastructure such as rain gardens or bioretention that rely on infiltration and evapotranspiration to function properly, or underground storage systems and pretreatment devices whose components are only accessible through lids and hatches, it's difficult to 'see' that green infrastructure is performing as designed. How can we fix it? Implementation ' Local communities are (or need to be) playing catch-up in terms of adopting the latest stormwater design criteria and BMP Manual for design of green infrastructure. Design ' Green infrastructure design criteria need to be updated to reflect technological advancements, constructability, maintenance needs, and an improved understanding of performance in the last decade. Additional detail and specification resources can help streamline design of green infrastructure, allowing design professionals to focus on creatively meeting project objectives rather than drafting aesthetics on plan sets, and syntax and diction of technical specifications. Construction ' Better construction resources should be available to green infrastructure contractors. Terminology clarifications and standardization of components and technical specifications can help produce clear drawings and specifications for contractors to build this infrastructure. Specifications should include experience requirements for integral components of green infrastructure, such as landscaping, that are not only critical to performance, but also perception of project success. As the resumes of local contractors increase with additional green infrastructure being constructed, resident project representatives knowledgeable on green infrastructure should observe construction activities to increase the likelihood that the infrastructure is built as designed. Maintenance ' Maintenance is most crucial during the establishment period for vegetated green infrastructure. Frequent weeding is important to landscaping components achieving their full potential as they grow in the first 3 years. Other components, such as pretreatment devices should be regularly maintained to remove sediment and other debris before it reaches more sensitive components of green infrastructure. A maintenance plan that considers the green infrastructure component and age of the facility should be developed to define frequency of maintenance activities and be implemented after components are installed, NOT AFTER PROJECT CLOSEOUT. Monitoring ' Not only is designing with maintenance access in mind important, design professionals should also factor in ways to monitor green infrastructure performance. Owners need to have a plan in place to actively monitor green infrastructure performance. Owners should plan for frequent monitoring and/or inspection of green infrastructure in the first 1- to 3-years as vegetation begins to establish and less frequently throughout the life of the infrastructure. Periodic monitoring can educate proactive maintenance to extend the life of green infrastructure. Be part of the solution. KC Water's Smart Sewer Program has taken major strides towards improving green infrastructure resources for designers and contractors. The following items have been developed and will be explained in the presentation so that others can improve their green infrastructure performance. Criteria Updates ' Strategically sized green infrastructure for rainfall events that are most likely occur, optimizing storage in a way that doesn't drown nor parch vegetation. Green Stormwater Infrastructure Manual ' Designing with construction, maintenance, and monitoring in mind. Clarification of green infrastructure terminology Design considerations for where/when to use various green infrastructure practices Guidance on sizing calculations for evaluating desired achievement Detail and specification templates to streamline design and provide consistency for contractors Site activity plan for proactive thinking on how to protect green infrastructure components from internal site erosion and sediment during construction Definition of Service Level Standards, identifying when maintenance activities should be performed Guidance for types and frequencies of maintenance activities National Green Infrastructure Certification Program (NGICP) ' Contractor education Selection Criteria ' Experienced based qualifications for the construction of green infrastructure (especially landscaping components) Maintenance Plan ' Plan for cleaning and repairing various components of green infrastructure. Monitoring Plan ' Plan for which green infrastructure need to be monitored when, what metrics are being measured, and how those metrics are going to educate maintenance operations. Adapt! Make changes if something isn't working. Green infrastructure is sustainable and resilient. These natural systems have the ability to adapt to changing climates. Policies and procedures for implementing green infrastructure need to be able to adapt too.