Road widening project shores up steep slope, mitigates erosion concerns

Dec. 7, 2017

The widening of a road around the south end of popular Lake Winnipesaukee in Alton Bay, N.H., created a steep slope (1H:1V) adjacent to the roadway. Concern that potential erosion and washout would occur during heavy rain events made stabilization of the 52-ft slope necessary.

Project objectives

Cost and aesthetics were major considerations for this project. Determining who would do the design work and installation were other issues for Ken Roberts, town road agent for Alton, to consider as he evaluated options. After reviewing a block retaining wall and Presto’s Geoweb slope system, the decision to use the Geoweb system was based on cost savings and design and installation support.

Design & construction

Local distributor E.J. Prescott worked with Presto’s design team to create a detail and specification. E.J. Prescott’s local contact Mike Everhart supported the contractor with installation training. The town’s highway department completed the installation. The 10,000-sq-ft slope project was installed in just a few days. The Geoweb cells were filled with topsoil and hydroseeded to ensure full grass coverage. Within four weeks, the slope was fully vegetated with dense, stabilizing grass.

The results

Before it was fully vegetated, the slope was exposed to multiple storm events with no damage or infill loss. “The Geoweb system held the material in place beyond expectations,” Everhart said. “Ken and his crew at the town of Alton highway department did a fantastic job on this project.”