Intermodal Rail Logistics Park Prioritizes Stormwater and Sustainability with Ecological Conservation Corridor in Kansas City

U.S. Army Corps of Engineers (USACE) accepted in 2019 post-construction monitoring as completed for the BNSF (Burlington Northern Santa Fe, LLC) Railway Company Intermodal Facility (IMF) mitigation conservation corridor located in the City of Edgerton in southwest Johnson County, Kansas. Presentation focuses on the successful design and implementation of nature-based (NB) stormwater management strategies associated with development of a complex industrial site as verified by annual monitoring. The purpose is to demonstrate that a carefully planned and designed ecological corridor can work in symbiosis with an adjoining industrial development to mitigate adverse impacts and enhance environmental benefits. Site is located approximately 35 miles southwest of downtown Kansas City, providing positive local context in support of the WEF SWI Stormwater Summit 2023 conference. The technologically advanced IMF enables efficient intermodal freight shipments within the BNSF rail network to the Kansas City region. Strategically siting the complex industrial development relative to key rail and highway transportation infrastructure required realigning approximately 2 miles of an unnamed Big Bull watershed tributary. Onsite mitigation was required to beneficially enhance, create, and restore the ecosystem functions and values of impacted wetlands and streams. The conservation corridor is excluded from future development or disturbance by perpetual easement, providing ecologically sustainable and long-term natural environmental benefits. Planning and design required considering watershed functions and values relative to stormwater management; water quality improvement; flood risk management; wetlands preservation; erosion control; and in-stream/riparian habitat conservation. The resulting ecological conservation corridor comprises approximately 59 acres; includes seven stormwater best management practice (BMP) areas; relocated stream with floodplain/floodway; and five restored wetland cells. Natural stream restoration techniques were used to realign the stream in a strategically sited and centrally located ecological corridor. Stream relocation included 31.23 acres of riparian buffer creation and 8.79 acres of riparian buffer enhancement. Development required realignment of 9,247 linear feet of a perennial stream to 7,747 linear feet of relocated channel with reference channel dimension, pattern, and profile. Riparian buffer areas included 16.75 acres of newly created shallow marsh and emergent/scrub-shrub zone wetlands for stormwater management. BMP treatment features manage site runoff from the IMF and surrounding areas prior to discharging into the relocated stream. At each stormwater outfall, a treatment train approach is used, including a forebay area (energy dissipation and sediment trap), constructed wetland area (water quality treatment), and vegetated outflow swale. A detailed water budget analysis evaluated the expected surface water runoff into the wetlands and modeled the hydrology of the wetlands to replicate natural conditions with the design. Onsite wetlands restoration included 7.18 acres not within riparian buffers, including a large emergent (herbaceous) wetland area in the center of the conservation corridor. Sustainable materials were primarily used to construct natural stormwater and erosion control features to provide water quality treatment for onsite drainage runoff before discharge to the relocated channel. Restored wetlands, riffles, pools, and ecologically designed drainage basins improve water quality, promote detention/infiltration, restore natural habitats, and mitigate indirect environmental impacts. Hard structures constructed with concrete and riprap were minimized. Where possible, onsite rock and vegetation were sourced for wetland and stream stabilization. Sustainable nature-based stormwater techniques and features utilized in design/construction will be presented. Relocation of the stream with detailed design of drainage features effectively reduced downstream peak flows and upstream base flood elevations (BFE). The realigned conservation corridor reduces the BFE at the upstream project limits by 3.63 feet. The first decade of operation has shown no evidence of channel instability (down-cutting, deposition, and bank erosion). Approximately 300-acre feet of annual runoff is routed through the wetlands. Monitored wetlands continue to demonstrate healthy and flourishing hydrophytic vegetation. The wetland detention ponds have successfully promoted nutrient reduction, sequestered carbon, recharged local water tables, and generally improved water quality. The naturally inspired conservation corridor and mapped floodway is a readily identifiable feature at Logistics Park Kansas City (LPKC). The corridor represents one of the largest local on-site mitigation efforts in Johnson County, providing habitat creation in conjunction with stormwater runoff treatment. Johnson County's Big Bull Creek Park is located immediately downstream of the conservation corridor, extending the corridor's environmental and water resource ecological conservation benefits into a 2,060-acre strategic prairie conservation and restoration area. The managed conservation corridor demonstrates the project team's commitment to minimize environmental impacts and contribute to long-term sustainability of communities served. The naturally landscaped floodway provides sustainable habitat for wildlife, waterfowl, and pollinators, while prioritizing stormwater and floodplain management. The presentation objective is to demonstrate how stormwater management functional requirements can be sustainably integrated with nature-based design features strategically sited within an ecological conservation corridor. The desired outcome is that the presentation will encourage participants to consider similar stormwater management strategies that are both environmentally beneficial and consistent with best management and design practices.