Multi-Use Trails Linking Destination Hubs around the City of West Des Moines
The Sugar Creek Greenway Trail project in West Des Moines is an integral part of the city’s Five Waters Project. When complete, the Five Waters Project will connect the Raccoon River, Blue Heron Lake, City Campus Pond, Jordan Creek, and Sugar Creek via a 26.2-mile trail, appropriately named the Marathon Loop. The Sugar Creek Greenway Trail will establish a four-mile-long section of that larger loop by connecting the future Raccoon River Trail with a future extension of the Jordan Creek Trail. Plans eventually call for the trail to continue north under Interstate 80 into the City of Waukee and create a connection with the Central Iowa Trails system.
Snyder & Associates has been actively involved in numerous roadway, environmental, and stormwater projects surrounding this planned trail corridor for many years. Due to our team’s success with these related projects, West Des Moines city leaders again partnered with Snyder and Associates to provide a Project Summary for the Sugar Creek Greenway Trail and prepare construction documents for the first of several construction phases which kicked off in 2020.
The current “phase one section” of the trail under construction consists of a six-tenths mile segment between Stagecoach Drive and Booneville Road. This includes several trail spurs that link adjacent residential developments and the construction of a 120’-long trail bridge over Sugar Creek that connects Woodland Hills Park located to the east of the trail section. The 12-foot wide, asphalt trail between Stagecoach Drive and Booneville Road generally follows the meandering Sugar Creek waterway over the length of this segment.
Seamless Construction Process Results from Project Coordination Efforts
This particular portion of the trail project touches on several other projects that Snyder & Associates took part in designing. This includes the design work for the Stagecoach Drive roadway extension and accompanying bridge over Sugar Creek, along with stream realignment efforts. To accommodate the new roadway bridge, a sharp meander in the creek needed to be removed, first. Additionally, the creek banks were armored to prevent erosion around the bridge abutments and a rock riffle was installed downstream to reduce overall erosion. The bridge and stream improvements were designed to accommodate the construction of the Sugar Creek Greenway Trail segment running along the west side of the creek and passing underneath the new roadway bridge. Our team also performed subdivision platting work for the adjacent Courtyards at Kings Landing senior community.
Thorough Planning Efforts & Environmental Studies Ensure Long-Term Trail Success
With design efforts dating back over a decade, numerous plans have been developed and several studies have been completed addressing various elements of this greenway corridor, including the stream restoration plan, stormwater conveyance improvements study, and a floodplain development plan, just to name a few. The Snyder & Associates design team used all of this relevant information in creating the Sugar Creek Greenway Trail Project Summary and phase one trail design.
Stream Restoration Planning
Guided by the design expertise of Snyder & Associates, the Des Moines Metropolitan Wastewater Reclamation Authority (WRA) is leading an effort to restore a portion of Sugar Creek between Booneville Road and Mills Civic Parkway. This portion of Sugar Creek is adjacent to existing sewer infrastructure. Through a holistic stream restoration program, the WRA aims to improve water quality and protect their infrastructure through this vital corridor. These efforts are funded through the State Revolving Fund (SRF) Water Resource Restoration Sponsored Projects program targeted at improving water quality in the State of Iowa.
Restoration techniques include laying streambank slopes back to improve stability, creating low-water floodplain benches, and adding low-water stream directive devices, like bendway weirs and rock riffle structures. The Sugar Creek Trail alignment was designed to accommodate the stream restoration efforts and provide trail users an opportunity to experience the restored natural area up close.
Stormwater Conveyance Improvements
The findings of a past study found that flood elevations and flood risk for the 1% and 0.2% annual chance floods exceeded expectations for the Sugar Creek area between Booneville Road and Raccoon River Drive. Several flood mitigation alternatives were evaluated to reduce flood risk potential and also reserve a corridor for flood conveyance and green space. The existing Sugar Creek bridges at the Iowa Interstate Railroad and Raccoon River Drive both suffered from inadequate water flow capacity. Since both bridges were scheduled for replacement due to deterioration, the preferred flood mitigation alternative included the replacement of both bridges with larger openings to increase flow capacity.
In addition to the new bridges, other improvements to the floodplain were needed, such as removing sediment that had accumulated over time and overgrown vegetation. Our team’s trail alignment plan was established within the confines of the proposed conveyance improvement corridor.
Floodplain Development Plan
A large portion of the Sugar Creek floodplain is located within city limits. Because of this, Iowa Department of Natural Resources (DNR) approval is required for bridge crossings and floodplain fill improvements, particularly in regards to maximum backwater and minimum bridge freeboard requirements. Although a small portion of the study corridor is located in unincorporated Dallas County, our team recommends adhering to this criteria as a standard practice for bridge hydraulic design in Iowa.
Bridges and Crossings Review & Analysis
Because the Sugar Creek Greenway Trail passes through a growing residential community, addressing numerous roadway and stream crossing points was critical for determining the final trail alignment along with plans for road and bridge redevelopment. Necessary improvements for the trail to pass under existing roadway bridges were identified at Booneville Road, Stagecoach Drive, the Grand Prairie Parkway, and eventually under the Interstate 80 Bridge as the trail expands to the north.
Additionally, trail design characteristics were established for future bridges along the trail alignment. This includes the future EP True Parkway, Wendover Road, Grand Avenue, and Mills Civic Parkway Bridges. As previously mentioned, a new trail bridge over Sugar Creek has already been constructed to connect the Sugar Creek Greenway Trail to the Woodland Hills Park area.
Natural Resources Analysis, Threatened & Endangered Species Protection
The Sugar Creek Greenway Trail project prioritizes natural resources protection and management to create the most environmentally friendly and sustainable design possible. Streambank stabilization efforts where necessary and native landscape buffers promote a healthy riparian corridor for trail users to enjoy. An extensive natural resources analysis was performed to minimize impacts to the area.
Likewise, to comply with the Endangered Species Act, extra measures were taken to avoid creating an imbalance in critical habitat. “Critical habitat” is a term that comes from the Endangered Species Act. It’s defined by the U.S. Fish & Wildlife Service as “specific geographic areas that contain features essential to the conservation of an endangered or threatened species and that may require special management and protection.” In Iowa, this is often considered the trees and riparian areas that are known habitats for certain bat and bird species.
A designation of critical habitat does not mean that development is impossible in that area. However, special precautions must be taken to minimize the potential impact on these species, such as clearing trees during the winter when bats are hibernating elsewhere. Our team performed a thorough assessment of the project area to ensure strict compliance with all applicable designations.
The Sugar Creek Greenway Trail project is planned to be completed over multiple phases (Segment Map) as land becomes available and funding for construction is allocated. The Snyder & Associates-led planning efforts for this legacy project include detailed cost opinions for each major phase. The careful planning by our team will allow for the successful completion of the Sugar Creek leg of the trail network and the seamless continuation of future trail expansion.