Sometimes you arrive at a potential job site where you know the client wants all the wood removed, and you ask yourself, “How are we going to be able to make this work?”
Occasionally, my company gets work for a logging and site-excavation company that does not have climbers on staff and needs unique tree work performed. I received such a call this past May to bid on a job involving a new septic-system installation behind a house on Lake Sunapee, here in New Hampshire.
The work site
In New Hampshire, we have extremely strict regulations for tree work to be performed within 250 feet of a lake, river or stream. This is because, in the past, loggers, tree workers and land owners would clear so many trees and so much vegetation along the shoreline that it would lead to erosion issues, deteriorate water quality and detract from the beauty of the natural landscapes the Granite State is famous for. This particular site fell right in the middle of the protected area, and a DES (Department of Environmental Services) Shoreland Permit was going to be required. While waiting for the “wheels of government” to turn for issuance of a permit, I was able to make a few site visits and produce a viable work order and plan.
The problem with the location of the new septic system was that it was going to be installed halfway up a bluff and gulley, where the slopes are heavily wooded and very steep. The pitch varied from 45 degrees to 70 degrees. Our job was to take down approximately 25 hardwood and softwood trees ranging in size from 6 to 24 inches in diameter at breast height (DBH). The majority of trees were northern red oak (Quercus rubra), eastern hemlock (Tsuga canadensis) and our state tree, the (American) white birch (Betula papyrifera). The brush material and as many logs as possible were going to have to be transported up the slope to an existing paved landing, where the new septic would be installed.
There was a narrow, steep, winding road adjacent to the bluff and landing. This led down and around to the carport and house on the lake. Unfortunately, limited lower-driveway access did not allow for removing and processing the material from below. As stated, everything was going to have to be transported up the slope. Due to the steepness of the grade, using a skidder, tractor or mini-skid steer was not an option either. Hauling everything up by hand was simply out of the question. Time to come up with an unconventional rigging plan.
Bringing in a crane is always my first choice on a job as large as this one, but with the terrain, that was not an option. The steep, narrow, switchback road where the landing was located was just too small and had high-tension wires overhead, which precluded extension of the crane boom had we been able to get one into that area.
So, what could we do? Having been a logging and mountaineering enthusiast for a number of years, I knew there were techniques and methods to deal with problematic sites like this one. It was just a matter of which one to use. My friend Norm Hall, an ISA Certified Arborist and master rigger, authored an excellent article that appeared in the December 2018 TCI Magazine, describing how he successfully used caving and mountaineering rescue techniques to transport wood from a site remarkably similar to the one we had on this job. This is a must-read article for every tree worker if they are going to be doing this type of high-lead work. (http://digimag.tcia.org/publication/?m=54984&i=547743&p=38&ver=html5).
In terms of forestry work, around the turn of the last century, Oscar Wirkkala, a Finnish American logger and inventor who lived and worked in the Pacific Northwest, produced the high-lead method of logging that utilized a skyline (or “spar”) and was ideally suited for the steep, rugged terrain of the West Coast. This revolutionized the industry. Being an ingenious man, he developed and patented many other important pieces of equipment for the logging industry that were used extensively during the first half of the 20th century. One such piece that we still use daily is the choker hook.
Many of the loggers who worked with Wirkkala were former sailors back in the day of wind, sail and tall-masted ships, when a vessel’s mast (aka “spar”) was used to transport both men and gear from ship to shore, and vice versa. This experience allowed these workers to quickly adapt to this new method of high-lead logging. For more about these logging and sailing rigging techniques, as well as the terminology used in each industry, I would recommend A Logger’s Lexicon, An Illustrated Guide for Logging Terms and Technology, by John T. Labbe, and the late, great master rigger Brion Toss’ The Complete Rigger’s Apprentice.
The work plan
In dealing with our particularly steep work site, I decided to use a high-lead (highline/trackline) system. It would combine techniques of logging, sailing, mountaineering and industrial rope access that would help make this job go smoothly and efficiently. One of the wonderful things about our industry is that we adapt and share different tools, techniques and methods with other high-angle industries. Even though mountaineering does not fall under a work-related industry, much of the gear and what they do can be related to tree work. This, to me, makes it especially important that we also look to them for ideas that may prove to be useful in keeping us safe and productive in our line of work. I call this form of sharing “cross-referenced rigging,” and I encourage others to take advantage of it.
Recently, I have noticed a trend with those in the tree care industry who are using high-lead/highline systems. Workers are choosing either the “English reeve” or the “Norwegian reeve” systems. The term “reeve” refers to the passing of a rope through a pulley or block. The difference between the two systems is subtle but worth noting when you are choosing one or the other for your work plan.
In a simplified version, the English reeve consists of a tensioned highline, one or two moving carriages, a control line below that passes through two pulleys attached to the carriages and a final pulley below, connected to the control line and the load to be moved. The lowest pulley allows the raising and lowering of the load and adds a 2:1 MA (mechanical advantage) to the system. The control line – after it passes through the second upper pulley – is terminated along with the highline to what is known in the logging/tree care industry as a “back spar” or “tail hold” (anchor) tree. (See photos 1a and 1b) Other rigging (both hardware and software) gear, such as carabiners, screw links, screw-pin shackles, rigging plates and Prusiks, also may be built into the system as needed. In tree-worker/lay terms, the reeve system allows us to easily transport loads – up and down – from point A to point B.
The English reeve is the Cadillac of hauling systems. It acts as a horizontal- and vertical-moving elevator. Due to the addition of the second pulley below the carriage(s), you spread out the distance between the two legs of rope supporting the pulley and load below. This eliminates the torquing and twisting action in the control line that can occur with other systems. However, the English reeve is more gear intensive than other haul systems, and can lead to additional job costs if equipment must be purchased.
As stated earlier, there are subtle differences between the two systems. The Norwegian reeve also consists of a tensioned highline, but only has one moving carriage and one pulley attached below it. A control line runs through the pulley and down to another pulley attached to the load to be moved. The control line then runs (aka “reeves”) back up and is terminated to the rigging hardware, which is connected to both the pulley and carriage. (See photo 2) This also provides a 2:1 MA. The beauty of the Norwegian reeve is its simplicity in the amount of gear needed and its ease of setup.
One thing to be aware of (which I do not really consider a disadvantage) is that, due to the control line being terminated at the pulley below the carriage and the two legs of the rope being so close together, sometimes the control line will torque and twist while the load is being raised/lowered. Often it will correct itself, and this really does not affect the strength or function of the reeve system. If, however, you are a rigger such as myself, who always tries to get a “fairlead” (the direction a rope runs, in a straight line, through the hardware to avoid chafing), then you could choose to use a swiveling pulley attached to the load to eliminate this “problem.”
Conducting the work
I settled on using the Norwegian reeve system for this project. Whereas in the past my crew has used various reeve systems, we decided on the Norwegian reeve because it fits with what we use for gear and for its ease of setup.
The first thing was to choose the location for the highline. We had plenty of trees to pick from, but I wanted to stay in the center of the landing as much as possible in order to stage the logs and chip the brush. Unfortunately, that left us with a hemlock tree approximately 10- to 12-inch DBH – not as large as I would have liked – as our “front spar.” I knew this tree was going to see tremendous forces on it and would need guying support from both the back and side, due to the way we would be loading it.
The highline consisted of a fairly new Sampson ½-inch Arbor-Plex line. Though not the ideal rope for this application (I would have liked to have had a more semi-static or static rope), I did have a lot of it and knew we were spanning close to a 125-foot distance. I also knew to keep all the loads within the safe specifications for this particular 12-strand line. The highline was reeved through a redirect pulley installed on the front spar, but not tensioned just yet. Once the highline and pulley were in place, I tied a back guy line adjacent to the highline and lightly tensioned it using a Maasdam rope come-along and a length of Sampson ½-inch, three-strand Tree-Master line. (See photo 3)
Because our pulling force was going to be perpendicular to our front, guyed-back hemlock tree, I also wanted to set up a side guy line that was as close to 180 degrees opposite our pulling force as we could achieve. This would cancel out the bending moments (levering action) that the vector forces would exert on the front spar when everything was tensioned and pulling evenly. In setting up a front or back spar (anchor pole) in this manner, it allows you to use a much smaller stem, if necessary, which we had to do with this particular location. We would use our trusty Hobbs H2 lowering/lifting device to tension (but not overtension) the highline, coming from the redirect in the hemlock. This would not only secure the highline, but also function as our side guy line, counteracting the opposite pulling force. (See photo 4)
Before we tied off the highline to the back spar, we needed to install our Norwegian reeve carriage system. (See photo 2) We kept the setup simple and used gear we already had with us. This consisted of a Petzl Tandon carriage pulley. Its distinctive design allows it to move horizontally without the worry of flopping over that you get with rescue pulleys and blocks. Connected to that was a steel, locking carabiner and a DMM Pinto Pulley. A Sampson ½-inch Stable-Braid rigging line ran through the Pinto, then down through a 2-inch CMI Service Line Pulley (which was connected to our loads) and back up to the steel carabiner, where it was terminated with a long bowline knot.
Also attached to the steel carabiner was our “haulback” line, which was nothing more than a “retired” Yale Blue Moon 11.7 mm climbing rope. On the carriage end of this line, we attached a ½-inch screw-pin shackle, which was then connected to the steel carabiner. This added a smooth interface without having to tie directly onto the long axis (spine) of the carabiner. As the haulback line was also going to function as a “snubbing line,” – temporarily holding back the load as it was raised – we needed to make sure no part of the gear would be loaded onto the gate of the carabiner. The snubbing/haulback line was tethered off at the base of the back spar with a Port-A-Wrap rigging device and managed by one of my ground workers during hauling operations. (See photo 5)
Our back spar was going to be a large red oak with sufficient diameter 35 feet up, where the termination knot would be. There was no need to guy it back. (See photo 6) Another option to use, in the event you do need to give the tree extra support or lessen the forces on it (as Norm Hall mentions in his article), is to run your highline through a rigging friction saver up in the tree, then down to a Port-A-Wrap at the base of the tree. This serves multiple purposes: (1) The resultant vector force between the two legs of rope will be at an angle instead of horizontal, which will lessen the bending moment on the spar; (2) the tension in the highline can easily be controlled from the ground, and; (3) in the event the back spar is not a removal tree, the friction saver can be removed from the ground without having to climb back up and untie a knot.
After we secured our highline with a half-hitch and running-bowline termination knot, we tightened the rope using the redirected Hobbs H2. [Note: A tensionless hitch (aka the “no knot”) would have been a better termination knot to use on the back spar, as it would have eliminated any excessive bending of the fibers in the highline, thus ensuring we used the rope to its optimal strength.] We kept the highline semi-taut but not super-tight. This would help reduce the vector forces. When tightening the highline, you need to be thinking about your rope properties, such as the percent of break strength and elastic elongation. Obviously, knowing what type of rope you are using is critical. All the necessary information can be found in the rope manufacturer’s spec sheets, which are available online. Again, though, these things should be thought out and discussed beforehand in the JSA (job safety analysis) and the work order.
Now is a suitable time to speak about highline tension. Too many tree workers new to highlines think they can just throw some ropes and pulleys up there and the system will work. This could not be further from the truth. You need to know the basic physics behind the system, the WLL (working load limit) of your gear and much more. You also need to be aware of force-multiplication and highline-tension formulas. (See Diagrams 1 & 2)
In physics, a force multiplier, such as a lever or wedge, increases the amount of force you can place on an object. In tree work, we think of force multipliers in terms of rope angles between anchor points and rigging points. The important thing to remember is that, as the angle between the legs increases, the resultant force on each leg also increases. If a 175-degree angle in the highline could be achieved (though highly unlikely), then a 100-pound haul load would have close to 1,150 pounds being felt by each anchor on the front and back spars. Definitely something worth thinking about! Unfortunately, space for this article does not allow me to go into detail on how to calculate highline tension and force multiplication, or how it applies in tree care situations. If readers are interested in tree-work applied physics, I can plan to make that a future article.
It was time to begin hauling. We wanted to get all the brush and as many logs as possible up the slope, but we needed to do so in a safe manner. Most of my calculations were done beforehand. Knowing that ½-inch Arbor-Plex has a breaking strength of 6,000 pounds and a WLL of 1,200 pounds (5:1 safety factor, which is standard in rigging work), as well as estimating our approximate sag-angle in our highline, I was able to use the force-multiplication chart and the high-tension formula to determine our safe working load (SWL). I calculated we could take loads in the 200- to 500-pound range without exceeding our safety parameters. Then, using the Green Log Weight chart and looking up red oak (which was the heaviest type of wood on this site), I found we could still haul millable-sized pieces of wood, albeit of a diameter not as large as I would have preferred.
Our hauling instrument to begin with was going to be our gas-powered Portable Winch. It has a 2.1-hp Honda 4-stroke engine and a 2,200-pound pull capacity at 60 fpm (feet per minute) with the smaller-
sized bollard that comes mounted on it. When you switch out to the larger bollard (which we did), your load rating drops to 1,500 pounds, but your speed increases to 90 fpm. Still, plenty of pull capacity for what we needed.
Since the bollard works as a spinning capstan drum, you are only limited by the length of your pull rope. I have a custom-welded, tree-mount frame for the winch that allows us to place it on small- and large-diameter trees. It also swivels, which allows torque-free movement and prevents damage to the motor. (See photo 7)
After yarding up a few “turns” (the material brought out of the woods by a single pull), we were quite pleased with the way the entire system was functioning. Since we were not going to haul beyond our working capacity, I decided to speed up the turns by switching from the Portable Winch to pulling with my Toyota truck in 4WD low. (See photo 8) This, too, worked exceptionally well and sped up the whole operation.
By the end of the afternoon, all the brush from that day’s work had been brought up and chipped, and we had a nice-sized log deck right at the top of the landing, which we did not have to move, thanks in part to the forethought and placement of the highline. (See photo 9) Much to my disappointment, though, that night I received a message from the logging contractor saying the State of New Hampshire had shut down the work site due to something being wrong with the permit. We had to go back and de-rig the entire Norwegian reeve system. Now I am just waiting for the “wheels of justice” and DES to allow us to go back and finish the job. Hopefully, by the time readers have received this issue, that work will be completed.
Overall, I highly recommend a high-lead/highline haul system anytime you have a bluff and gulley site that requires unconventional rigging. I also want to give a big shout-out to my crew, Brandon Eldridge, Drake Simpson and Sam Wagner. Without them, I could not have accomplished this job.
Chris Girard is an ISA Certified Arborist, a Society of Professional Rope Access Technicians (SPRAT) Level 1 Technician and owner of Girard Tree Service, a 15-year TCIA member company based in Gilmanton, New Hampshire.