Texas Forestry BMPs - Constructing Waterbars and Wing Ditches

Texas Forestry BMPs - Locating Waterbars

March 2013 BMP Q&A

By: Todd Thomas, Water Resources Forester, Texas A&M Forest Service

Q:  I was looking at a Texas BMP compliance monitoring checklist and in the comments section, it mentioned “below grade roads”.  I have heard this term mentioned before, but I have never been quite sure what a below grade road is and what exactly can I do about them?

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

Below grade roads usually occur after years of being worked and graded without any new material brought in to build them up, or from just being worked from one direction, to the point that the road essentially becomes a channel for runoff water.  As you may remember, with BMPs we are trying to keep from channelizing any runoff.  When runoff is channeled it begins to accelerate, especially in areas with a great deal of topography.  This accelerated runoff will increase erosion and the amount of sediment that reaches our streams. 

The issue of below grade roads is not limited to areas with rolling terrain or steep topography, below grade roads can create significant problems in flatwoods as well.  The issue isn’t so much a concern with water quality, but with access.  Water will always flow to the lowest spot on a site, and if this happens to be the roadway, then the water will not 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, the first thing you need to decide is if the road 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.   If the road is not necessary then it should be closed.  In order for the road to stay in use the surface will need to be built up and water control structures will need to be put into place.  The type of structure will be dictated by the traffic type.  

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 dealing with temporary roads, revegetating is a great option to hold the soil in place and minimize the amount of erosion and sedimentation that may occur.  A more cost efficient way to hold temporary roads in place is to distribute fine slash on the roadbed.  If you have any questions about BMPs, please do not hesitate to contact me at (936) 639-8180 or email me at tthomas@tfs.tamu.edu.  

*This article was published in the March 2013 edition of the Texas Logger

March BMP Q&A

By: Shane Harrington, BMP Forester (Ret.), Texas Forest Service

Q:  I recently inherited a tract just outside of Palestine.  The property has only one access road and over the years it has gotten in pretty bad shape becoming impassible.  The road has deep gullies running through it and appears to be below grade.  The road also travels across a bottom with moderate slopes (5-10%) and crosses a perennial stream.  I want to have permanent access to the tract so what options do I have to achieve this.  I also wanted to know if you are ever able to go out and give “on the ground” advice and suggestions concerning BMPs?

A:  First of all yes, loggers often call us and ask us to come out and give “on the ground” advice or suggestions regarding BMPs. 

Now lets get to your question about your access road.  It sounds like your road has gotten in pretty bad shape over the years.  I would like to start by saying that it is important that you consider using water control devices during any reconstruction of your road.  This is important because these devices will divert water off the roadway and help protect the site from excessive erosion.  Because the road will see a moderate amount of traffic during the reconstruction process and afterwards rolling dips should be used to divert the water and prevent excessive erosion.  Specifications for properly installing rolling dips can be found on pages 45 and 46 of the Bluebook.

A below grade road will constantly cause you problems.  In my opinion, the best thing to do is to have a dozer cut down the surrounding land and use this dirt to build up your road.  This will also help provide a natural outlet for diverted water.  Additional dirt may have to be brought in to finish building up the road to the desired height.  A mixture of dirt and rip rap may be used to build up the approaches.  This will make the approaches more stable and minimize any erosion on the approaches.  Crowning and seeding the road will also help stabilize it reducing the potential erosion hazard.  For proper seeding choices and rates see pages 64 and 65 of the Bluebook.

Lastly lets talk about what type of stream crossing you should install.  Since you want permanent access to the tract this means that you will have to install a permanent crossing. I would suggest installing a culvert if it will be able to handle the expected water flow.  To determine what size culvert to use refer to the Culvert Size Chart on page 50 of the Bluebook.  You want to make sure that you install the right size culvert because putting one in that is too small will eventually blow out.  A blown out culvert will cause more road problems, increased repair expenses, but more importantly it will impact the water quality of the stream through the high amount of sedimentation caused by the blown out culvert.  The Stream Crossings section on page 47 of the Bluebook also contains specifications on how to properly install a culvert.  If a culvert will not provide an adequate crossing then you may have to think about installing a bridge.  For this I would suggest that you get technical advice from someone specially trained in this area or contact your local NRCS office

Proper road construction and maintenance can be time consuming and expensive but are necessary if you want good access to your property.

If you need a copy of the Bluebook you can get a copy from your local Texas Forest Service office or you can view online at http://txforestservice.tamu.edu/water. If you have any questions or comments about BMPs please call me at (936) 639-8180. 

* This article was published in the March 2004 issue of the Texas Logger                                                                                                                                                                                                                                                      

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