May BMP Q&A

By: Hughes Simpson, BMP Forester, Texas Forest Service 

Q:   I just received a copy of the Texas BMP compliance monitoring checklist and noticed in the comments section that the term “below grade road” was used. What exactly is a below grade road, and why is it a problem? What can be done to correct these types of roads?

A:   I am glad you asked this. A below grade road can best be described as one that is lower than the surrounding land. Many of the roads in East Texas are very old and will fall into this classification.

Below grade roads can pose a serious impact to water quality. Roadways that are actually lower than the surrounding land can act as a channel for runoff water. In areas with rolling terrain or steep topography, these “channels” can accelerate the flow of water and increase the amount of erosion that will occur. This can lead to eventual sedimentation into our streams.

This type of problem is not only limited to moderate or steep slopes. While below grade roads in the flatwoods might not contribute a significant impact to water quality, they do present an access problem. Water will always flow to the lowest spot on a site, and if this happens to be the roadway, then the water will not be able to properly drain. The road will then become saturated, and stay wet for most of the year. Wet roads can lead to poor access, and cause severe rutting if traveled.

These situations can develop gradually over time if roads are not properly constructed or may occur when subjected to heavy rains. The formation of these areas can also result from trying to access a wet road by cutting it down until a dry surface is reached. While this might be a temporary solution to an access problem, it can lead to erosion problems.

To fix or reduce the severity of these problems, you must first decide if the area in question will function as a temporary or permanent road. This can be dictated by the amount of traffic your road will handle in the near future. High traffic zones will generally be more expensive to control than low traffic zones.

There are several effective ways to reduce the impact to water quality on below grade roads. It is best to make sure that the roadway is well drained when dealing with permanent systems located on steep topography. Installing waterbars with good outlets for the water is recommended. Instead of using the dirt in the roadway to build these structures, try incorporating some of the bank dirt. This will allow you to construct a waterbar and at the same time make it easier to divert the water.

When handling temporary roads, you can always consider reseeding or applying fertilizer to the area. This will help establish vegetation on the site that will serve to hold the soil in place and minimize the amount of erosion and sedimentation that may occur. A more cost efficient way to accomplish this is to add brush and logging debris to the roadbed. If you have a question regarding BMPs, please call me at (936) 639-8180.

* This article was published in the May 2001 issue of the Texas Logger