Sunday, June 1, 2008

June BMP Q&A

By: Jake Donellan, BMP Forester (Ret.), Texas Forest Service

Q:  In your opinion, if loggers had to focus on one specific BMP or area of BMPs what would it be and why?

A:  In evaluating BMP implementation all over east Texas, I see a lot of logging operations. Each logging operation is very different and yet the same elements are present on the majority of the sites I see. If I could get loggers to focus on one thing specifically it would be stream crossings.

I know we have beat this drum for a long time now but it really is a critical area of any harvest operation. Stream crossings are critical areas because this is where loggers can potentially have the greatest impact to water quality if precautions are not taken. As most of you have learned, sedimentation is the biggest concern with forestry operations and 90% of the sediment load comes from our forest roads. It is fairly clear to see that where our roads actually come into contact and cross streams, we have a recipe for problems if attention is not paid to protecting water quality by using proper BMPs.

Removing temporary crossings seems like a very simple task to undertake, it always amazes me when I run into temporary crossings that are left in streams. Most “temporary” crossings that are left behind are typically brush type crossings. These types of crossings do allow some water to pass through which makes them extremely useful to use during the operation. The reason they need to be removed is because they still impede water to a degree and also they trap debris on the upstream side of the crossing. Eventually they become blocked with leaf litter and become in effect a dam. Once this happens, it is only a matter of time before a blow out occurs and an extremely large sediment load around the crossing is eroded away and into the stream channel. This process is sped up during periods of high flow for the stream like during a major rain event. For this reason, most of these types of problem areas are considered significant risks to water quality both in real terms and also on the BMP Implementation Evaluation form. This process holds true for other types of temporary crossings left behind such as pole crossings or log crossings. According to at least one logger I spoke to, it takes less time to remove a brush crossing than it does to install it, and for that reason alone, there should be no reason a temporary brush crossing should ever be left behind.

Temporary crossings that are left in place following an operation can pose a significant risk to water quality

Another BMP as equally important as removing a stream crossing is stabilizing stream crossings and approaches. A lot of good work can be undone by simply not stabilizing the approaches. Approaches have to be stabilized because of their proximity to the stream channel itself. This limited amount of area provides little room for error when it comes to implementing BMPs properly. You can stabilize the approaches by laying down slash, laying down hay, seeding grass, and when necessary installing water bars. Water bars should only be installed on approaches if it is absolutely necessary to prevent a washout occurring on the approach due to steep slopes or moderate slopes on sandy sites. Again, because of the nearness to the stream if water bars are used, they must be installed properly at a 30 to 45 degree angle, 1 to 2 feet in height, tied in properly on the uphill side and venting water off the approach but not directly into the stream itself. When approaches are not stabilized, what typically happens is water begins finding its way down the approach and into the stream and before long a head cut starts right at the stream bank eroding sediment directly into the stream. Rain intensity, slope, and soil type all play a roll into how rapidly the head cut advances back up the slope and ultimately how much sediment is eroded into the stream. Stabilizing with rock or geo-textiles may be considered or necessary on approaches to permanent crossings.

These two areas, removing temporary crossings and stabilizing crossings and approaches, have consistently been problem areas for loggers throughout the history of BMP implementation monitoring. As I have pointed out numerous times, we already have been successful in implementing BMPs but that is no reason to sit on our laurels. If we, the forestry community, focus on addressing these two issues, I think we will have succeeded beyond anyone’s wildest expectations.

For more information regarding BMPs consult the Texas Forestry Best Management Practices book (a.k.a. the “Bluebook”), contact your local Texas Forest Service office, or you can contact me.

* This article was published in the June 2008 issue of the Texas Logger