Corridor H and the Cacapon River

Sections of the Corridor H four-lane highway are now being built in the Cacapon and South Branch of the Potomac watersheds. No matter what you think about this highway, now that it is being built our concerns must shift to the impacts of construction on our environment. The biggest initial threat to our rivers is sediment laden runoff from construction sites. 

Our December 2001 Cacapon newsletter has a feature article on the issue of erosion control on highway construction sites.  The following pictures illustrate the construction process and the erosion-control measures, or Best Management Practices, intended to keep the construction site sediment  out of our rivers.

Getting Started - 

Setting up Construction Offices, Clearing and Grubbing

The process begins by clearing space for construction offices.  Heavy equipment is brought to the site.  Following this, the highway's path is "cleared and grubbed" (i.e.: trees are cut, stumps and pulled, debris is burned).  For those of us with an attachment to certain scenic vistas and places, this phase of construction is the most "apocalyptic."  This is also the phase where erosion control is the most difficult.  Note the silt fences on each side of the stream in the mid-ground area in photo 2.

Cut and Fill

After the land has been cleared, heavy equipment is used to shape the land, drilling, blasting, cutting and filling to bring the road to final grade.

Erosion Control

The scale of highway construction projects creates special challenges for erosion control.  These projects expose a huge amount of acreage to erosion.  Whether cutting, filling or shaping the margins, these sites are in a constant state of change (see above pictures). This activity is particularly dynamic when you build in mountainous terrain.  Black silt-fences and hay bales are little more than band-aids on a gaping wound for a site as large as a four-lane highway.  The builders also have a problem with very fine sediments (in part created by blasting and heavy equipment) that erode easily and remain in suspended in the water for a very long time. 

 Erosion control demands constant attention in order to be effective.  As the road surface is shaped, it is brought up (or down) in such a way that water will flow to the edge. Water flowing along that edge is contained by a low earthen berm and flows to a low spot. At the low spot, a hole in the berm allows the water to flow off the road's surface into a large black plastic pipe, known as a pipe slope drain. The water is carried down that pipe to a sediment pond -- the lynchpin of the entire process.