June 2013 BMP Q&A

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

Q: When harvesting trees within an SMZ I've always been told to keep tops and slash out of the stream, however, when you walk along a stream in the forest there are tons of limbs already in the stream. What is the big deal?  I know it is a guideline, but why is it so important to keep limbs out of the stream when there are already so many there naturally?

A: You bring up a good point, but since there are in fact lots of limbs and debris in the stream bed, there is no need to add any additional debris.  First and foremost, the more debris that gets added to a stream the greater the likelihood of the stream being dammed up and as a result causing flooding.  Flooding is going to happen from time to time with heavy rains, but the less floods in these forested streams the better.  With excessive flooding comes the potential for more erosion on a site, as well as the potential for nutrient loss in the soil.  As the flood waters recede, the eroded soil and nutrients are then carried to the stream, severely affecting water quality.  This flooding could also cause a reduction in the amount of water downstream, further affecting other bodies of water.

Build up of slash in an intermittent stream in East Texas

With the increase of limbs in the stream also comes more scouring or erosion of the stream bank itself.  Since this already occurs naturally, additional scouring can be problematic.  The first issue comes with more sediment in the stream.  More sediment traveling downstream has many negative effects on water quality as well as on aquatic plants and animals.   This increased scouring also releases nutrients that were once stored up in the soil of the stream banks.  As more nutrients travel downstream, they can accumulate and degrade water quality. 

Another benefit of keeping the slash out of the stream is being able to utilize the slash elsewhere on the tract.  Slash is an excellent tool for erosion prevention on closed out skid trails and temporary roads.  Why contribute to a problem when something can contribute to a solution? 

In conclusion, keep slash out of streams, the folks downstream will thank you, aquatic life will thank you, and the landowner will thank you.  Remember extra debris in the stream contributes to flooding and water quality degradation.  Remember to keep the questions coming, you can send them to me at tthomas@tfs.tamu.edu or just phone it in by calling (936) 639-8180.  

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

May 2013 BMP Q&A

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

Q:  One type of temporary stream crossing that I have heard mentioned, but never seen or even heard discussed in great detail are PVC bundles.  What exactly are these and how can I construct my own?

A:  Excellent question about an innovative stream crossing method.  PVC bundle crossings can be constructed relatively cheap from readily available materials and can be re-used and repaired without issue.  While not suited for large streams, PVC bundles can be used on most ephemeral and intermittent streams with a U-shaped profile that are not more than 10-feet wide and 4-feet deep in channels with low flow.  Think of these bundles as a large handful of straws. 

In order to create a 12-foot wide pipe bundle that is 16-feet long when laid flat, you will need 12 20-foot joints of 4-inch diameter schedule 40 PVC pipe, four 18-foot lengths of 3/16 inch galvanized steel cable, and eight 3/16 inch cable clamps.  The 20-foot joints of pipe should be sawed into 12-foot sections with the remaining eight feet sawed in half so there are two 4-foot joints, per 20-foot joint of pipe.  Next, drill ¼ inch holes completely through the 12-foot long joints at locations 2-feet and four-feet from either end; on the 4-foot long joints, 2 ¼-inch holes should be drilled, each 1-foot from the end.  Alternate one 12 foot long joint with one row made of two 4-foot wide joints placed 2-feet from each other.  Finally, you will connect the joints of pipe.  To do this, string each strand of galvanized cable through the holes in each joint of pipe.  Once strung through, make loops on the ends of each cable and secure them with the cable clamps.  Each cabled section should be loose so pipes can conform to the stream channel.  When you are done there should be 2 4-foot sections of PVC remaining, these can be used at your discretion.   

In order to utilize your newly constructed bundle, begin by lying on end of the pipe bundle at the top of the bank and allow the rest of the bundle to lie in the stream channel slowly piling it back on top of itself.  The ends of the bundle should be resting on banks opposite each other.  The loops in the cable can then be used to tie off the bundle to anchor points on each side of the stream.  You may want to lay boards across the bundle perpendicular to allow for better traction when crossing.  When it is time to remove the crossing, simply undo the anchor points and lift the bundle out by the cables that are attached the pipe on top.  After the bundle is removed be sure to inspect it for any damage and replace any damaged pipes before re-use. 

Once the bundle has been removed, always remember to stabilize your approaches, just as you would with any stream crossing.  Also, keep in mind where appropriate stream crossings should be located: straight sections of stream that can be approached at a 90-degree angle.  This concludes this month’s BMP Q&A, remember you can send any questions to me at tthomas@tfs.tamu.edu, or you can phone them in by calling (936) 639-8180. 

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

What to consider: Culverts

Poorly installed and improperly designed culverts can lead to excessive erosion, damage to streams, high maintenance costs, and road failure.  In order to prevent these issues it is important to consider culvert type, diameter, length, and location.

Excessive sedimentation from a poorly planned culvert

Type
There are two types of culverts: stream crossings and cross drains.  The first type, a stream crossing culvert, is generally placed in a location where a permanent stream crossing may be necessary, since it is often too costly both economically and ecologically to remove. These culverts allow both stream flow and aquatic wildlife to pass underneath the road.  The second type, cross drains, are used to transport upland runoff, accumulated in road ditches on the upland side of the roadway to the lower end where both flow volume and velocity can be dissipated.

Mouth of a cross drain culvert

Diameter
Culvert diameter is determined by both the soil type on the site, how steep the site is, and the acreage of the watershed that the culvert drains.  Taking into consideration these factors ensures that the culvert is sizable enough to handle the maximum volume of water that it may encounter.

Culvert size chart from page 51 of the Texas Forestry Best Management Practices Handbook 

Length
Culvert length is dictated by how wide the road is.  Culverts should be long enough so that each end extends at least one foot beyond the edge of the fill on either side.

Location
Culvert location is paramount in dictating the longevity of the culvert.  In stream crossings, culverts should be placed in a section of stream where the channel is straight and the stream bed is firm.  Cross drain culverts should be spaced out depending on slope.  Cross drain culvert spacing can be determined using the following formula:

Culvert spacing = (400'/slope%)+100
         *Slope in percent is expressed as a whole number (i.e. 15%=15)
               
            Example: Spacing = (400'/15)+100'
                          Spacing= 127'

Conditions
In addition to factoring in culvert specifications, it is also extremely important to factor in current weather conditions and trends.  Culvert installation should be done when stream flows and chance of rain are low.  Ideally, the entire installation process should be completed before a rain event.

UP NEXT:  Installing your culvert

2013 Texas Wildlife and Woodland Expo

On Saturday thousands of visitors descended on the Lone Star College-Montgomery Campus in Conroe to learn about the forests of the region in which they live and how to best take care of it through hands on clinics, information booths, live demonstrations, and children's activities.  Attendees ranged from urban homeowners to rural landowners, boy scouts, girl scouts, outdoor enthusiasts and everyone in between.

Donna Work explains the importance of streamside management zones using the SMZ simulator

Hughes Simpson discusses benthic samples with visitors

The Water Resources program was on hand to answer questions related to water resources and provide information on forestry BMPs.  Donna Work, Hughes Simpson, and Todd Thomas handed out information and discussed BMPs and the forest-water relationship to any interested patrons of the event.  A demonstration was on hand to illustrate the importance of maintaining Streamside Management Zones (SMZs) complete with rainfall and runoff simulation.

Todd Thomas talks BMPs with expo enthusiasts 

SFA Students Experience BMPs Firsthand

Last week, 46 students enrolled in ecology at Stephen F. Austin State University were able to view various Texas forestry best management practices (BMPs) implemented on the ground in northeast Nacogdoches County.  In addition to viewing methods of erosion control in forestry operations, the students learned about various facets of the program including the effectiveness monitoring project.  While learning about the BMP effectiveness project, the students were able to view equipment used to sample benthic organisms, as well as some organisms that were living in the creek running through the tract.

Biologist Donna Work discusses benthic macroinvertebrates 

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

February 2013, BMP Q&A

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

Q: In the quiz last month you asked a question where we would need to know the slope in order to have appropriately spaced windrows.  My question is how are we supposed to know the slope in the field off hand without a tool such as a clinometer? 

A: I am glad you asked this question and I am always glad to highlight areas of the blue book.  However this time I will not be referencing the text of the book, but a feature that many of you may have noticed, but never paid much attention to.  This feature is the slope calculator. 

The slope calculator can be found on the inside of the back cover of the blue book.  There are instructions on how to use it, but since you asked, I will go ahead and explain.  In addition to your blue book, you will need a piece of string, approximately 12-inches long and something to use as a weight, such as a small nut or washer.  First, tie one end of the string to the middle ring of the spiral binding or punch a hole through the cover of the book at the apex of the slope calculator.  Go ahead, it is okay.  There is a small circle there for your reference.  Next, tie your small weight to the loose end of the string. 

Now that your slope calculator has been constructed, here is how you will use it.  The spiral binding should be on top, use this as your sight.  With the binding parallel to the ground, sight the book up or down the slope (depending on which way you are facing), the string will hang vertically and the slope can be read directly along the line where the string lies.  The number on the line with the string is your percent slope.

Now that you are aware of the slope calculator, there are no excuses for not having your blue book with you.  Not only is the book full of BMP information, it is also a tool that you can use in your day to day functions.  In addition to windrow spacing, this tool can be used for determining road gradients so you know where to locate your water control structures such as waterbars, wing ditches, culverts, and dips; in conjunction with the culvert size chart to determine culvert sizing; as well as how wide to make SMZs when near steep slopes, or any other time you need to know the percent slope in a pinch. 

In conclusion, keep those blue books handy, you never know when one might come into use.  If you need a blue book you can get one from your nearest TFS office.  Please keep your questions coming.  You can email them to me at tthomas@tfs.tamu.edu or phone them in by calling (936)639-8180.  

*This article was published in the February 2013 issue of the Texas Logger