Phased Projects: An Opportunity to Apply Design & Construction Lessons Learned at Methodist University
Rebecca Stubbs, PE
Ben Tharrington, PE
McAdams
Raleigh, NC
Darrell Westmoreland
North State Environmental
Winston Salem, NC
Author: Stubbs, R., PE, Westmoreland, D., Tharrington, B, PE
Designers and contractors don’t always have the opportunity to return to the same site to design and construct a subsequent phase of a restoration project. Phased restoration projects provide the design-build team an opportunity to reflect on both the prior phase’s successes and recommended revisions based on encountered site conditions. On
Methodist University’s campus, McAdams designed and North State Environmental constructed a 2,200 linear foot stream restoration project as Phase 1. Once construction of Phase 1 was completed in 2020, McAdams worked with Resource Institute and the University to aggregate funding for the design and construction of Phase 2 to restore another 2,700 linear feet of stream.
This case study phased project restored several unnamed tributaries to the Cape Fear River and is located along the inner coastal plain in Fayetteville, NC and is generally characterized by the challenging combination of sandy soils with rolling topography. The pre-project channel was severely incised resulting from active bank erosion that created bank heights ranging from 15-20 feet. Phases 1 and 2 applied a Priority Two restoration approach to establish a bankfull bench within the steep sandy side slopes and connect the restored stream channel to a regularly accessible floodplain. During construction of Phase 1, site conditions proved to be especially challenging and field modifications to the approved design were required to address: concentrated runoff from the surrounding developed campus, adjusting channel dimension to prevent bank washouts prior to vegetation establishment, material substitutions used for runoff conveyances resulting from poor subsurface conditions, matting the entire floodplain bench, and increasing bank vegetation.
As the design-build team approached Phase 2, lessons from Phase 1 were incorporated at the initial stages of design development. This included reducing average stream slope, concentrating stream elevation drops into a few boulder cascade structures, increasing feature lengths and radius of curvature, planning for additional coir matting across the floodplain bench, bolstering the planting plan based on densities and species that performed well in Phase 1. Construction of Phase 2 is beginning in January 2025 with anticipated completion date of September 2025.
About Rebecca Stubbs, PE
Coming Soon
About Ben Tharrington, PE
Coming Soon
About Darrell Westmoreland
Coming Soon