Project Overview:

Years of runoff from an adjacent highway had caused severe erosion of a 2H:1V embankment at an 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 as deep as 4 feet. A repair was necessary to prevent further erosion, but a wetlands at the bottom of the embankment prevented flattening the slope. A turf reinforcement mat was considered, but due to the severity and potential for reoccurrence, a stronger cover solution was necessary.

Repair Solution:

The Maryland State Highway Administration (MDSHA) chose the Presto GEOWEB system—successfully used on a previous project. By design, the GEOWEB slope system’s 3D structure confines and stabilizes topsoil on steep slopes, where the confined infill remains stable and minimally affected by surface runoff.

Results:

Approximately 29,000 sf of the GEOWEB material was placed and anchored on slopes varying between 50 and 75 feet in length. Presto’s engineering team collaborated with MDSHA’s consultant Schnabel Engineering Consultants, on a design solution specific to this site. The solution for this site included the GEOWEB GW30V (mid-size cell), 4 inch depth material with 3 foot ATRA® anchors on three foot centers. A double-sided erosion control blanket was included as a surface treatment to provide erosion protection during the germination period. Representatives from Presto’s distributor ACF Environmental were on site for three days assisting the contractor with installation.