Project Name: Maryland State Highway
Project Location: Salisbury, Maryland
Over time, runoff from an adjacent highway caused severe erosion of a 2H:1V embankment at the U.S. Rt. 50 & Naylor Mill Road interchange in Salisbury, Maryland.
Sloughing of large sections of the upper topsoil layer exposed the clayey sand embankment soils to surface runoff, which developed into rills and gullies that were up to 4 ft. deep. To prevent further erosion, a repair was deemed necessary.
Wetlands at the bottom of the road embankment prevented flattening the slope. A turf reinforcement mat was considered but ruled out by the project engineer for the Maryland State Highway Administration (MDSHA). The severity of the problem and potential for reoccurrence warranted a stronger type of cover solution.
The MDSHA turned to a solution they successfully employed on a previous project—the GEOWEB® 3D Soil Stabilization System. The GEOWEB system’s 3D structure is designed to confine and stabilize topsoil on steep slopes. The confined infill remains stable and is minimally affected by surface runoff.
Approximately 29,000 square feet of the GEOWEB material was placed and anchored on slopes varying between 50 and 75 feet in length.
THE DESIGN SOLUTION
Presto Geosystems’ Chief Design Engineer, Bryan Wedin, PE, collaborated with MDSHA’s consultant, Steve Fung, PE., of Schnabel Engineering Consultants, to provide a solution specific to this site. Presto evaluates each project individually and recommends a solution including the GEOWEB cell type, depth and anchoring components, and spacing.
For this site, the solution included the GEOWEB GW30V (midsize cell), 4-inch depth material with 3-foot ATRA® anchors. The anchor pattern was on 3-foot centers.
ATRA® keys were used to connect GEOWEB sections side to side and end to end. They engage through slots in the GEOWEB material and “lock” into place, making them an efficient and safe way to permanently connect sections, especially in difficult-to-access areas with 2H:1V slopes.
A double-sided erosion control blanket was included as a surface treatment to provide erosion protection during the germination period.
CONSTRUCTION SITE SUPPORT
John Easom, ACF Environmental, was on site for three days to provide installation support to the contractor, David A. Bramble Construction, per contract requirements.