Trail Leaders Trained in Erosion Control Techniques

On Saturday, a small cadre of trail volunteers were provided detailed training in advanced erosion control techniques, using rock armoring of the trail, rolling grade dips and a type of “mini-dip” known as a nick. The project was part of the Forest Service burned area recovery program (BAER), which provided funds to help deal with the impacts of the recent Jesusita Fire on Tunnel, Jeusita, Rattlesnake and West Fork of Cold Spring trails.

“We don’t a lot of money for the trail work,” Santa Barbara District Wilderness Trail Manager Kerry Kellogg noted at Steven Park, where the fifteen volunteers assembled. “However, it does provideus the opportunity to bring in several CCC crews over the next month to work on reinforcing existing water control features and redesigning others.”

To train the CC crews in the more advanced techniques and to identify problem areas, Kellogg was also able to hire a trails engineer from the Lake Tahoe Basin Management Unit, Garrett Villanueva. Villanueva has hundreds of hours of experience in dealing with similar trails in the Lake Tahoe area as well as working with volunteer groups and he offered to spend a Saturday with our local Santa Barbara trail volunteers to help train them as well.

After a safety talk Villanueva provided a brief introduction to dealing with getting water off the trail. “What we are talking about is hydrologic connectivity,” he said. “That’s the ability of water to flow along a path for long periods of time. We need to be able to break up that flow – specifically on trails – so that the water is never allowed to continue down them for more than 20-30 yards at a time.

“If we were building new trail we could do that by keeping the grade (or steepness) down and adding grade reversals, or spots where the trail climbs or drops for short distances, but most of the time when you’re working on established trails you don’t have that option so you use other trail features like rolling grade dips to provide a similar effect.”

As the group assembled at the bottom of Tunnel Trail Villanueva explained what’s involved in building such a dip. With tape measure in hand he marked out a 24-foot-long distance, marking the beginning, middle and ending points. “Here are the basics,” Villanueva said. “A true rolling grade dip needs to drop gently and then rise back up gently, with a drop that’s enough so the water can’t continue down the trail but with a length that is long enough the trail user hardly feels that it’s there. Thus the 24-foot length: that’s 12 feet in and 12 feet out.

“The trail is fairly steep here,” Villanueva also noted, “and it’s gullied too, which makes it seem like it’s almost impossible to get the water out of the gully and down the hillside but it’s not.

“To create the dip, the trail needs to drop gradually to the low point of the dip before it rises again. If the gully is deep like it is here, we can fill part of the gully with a layer of rock and then move the soil from the outside berm into the gully to fill it in and cover the rocks. That accomplishes three things: it helps reinforce the trail by armoring it with rock, the dip is created without having to move as much soil and less material is available to erode down hill next time it rains.

“But that’s not all,” Villanueva added. “We also want to make sure that the lower berm doesn’t wear down over time or eventually the water will end up back on the trail and we need to make sure it is high enough so water doesn’t flow over it and on down the trail. So we need to armor the lower end with rock to hold it in place and berm it up.” About this time Villanueva was getting a few puzzled looks and a number of questions. Finally he said he said with a chuckle, “Sometimes it’s not easy to visualize what’s required to make a good dip so let’s try making a few.”

Spitting into three groups, over the next few hours the volunteers slowly began to work out the process of designing and building their dips. With plenty of rock nearby and easy-to-work soil thanks to the recent rain, the work went quickly.

First, rock was collected for use in armoring the trail. Then trenches were cut at a 90 degree angle to the trail at the lower end of each of the dips, far enough into the hillside and outside berms to create solid anchor points. Then large rocks (the 200 pound type) were gently lowered into the trenches and set side by side, with their edges lined up to help lock them in place. Finally then, smaller rocks were placed into the cracks to lock them together even more with a final “keystone” rock set as the final piece of the puzzle.

Once the lower part of the dip was armored, other volunteers then began to cut into the middle part of the dip, moving dirt from the outer berm to fill in the gullies. “Don’t knock that dirt down the hill,” Villanueva reminded the group. “We can use that to cover the parts of the dip that we just armored.

Slowly each of the dips began to take shape. In places where the gully cutting down the trail was really deep, small rocks were added to provide additional armor to the tread. Then the higher parts of the outside edge were knocked off and moved uphill to cover the rocks. In an hour the dips had begun to take shape as the volunteers began to understand the concepts. In another half hour they were ready for inspection.

“Great work,” Villanueva shouted out. “Now there are only 89 more spots like this I’ve flagged above here on Tunnel Trail,” he said with another laugh. “Let’s go tackle another few of them.”

Hopefully the CC crews will be as willing and able as were these fifteen dedicated workers. But then, if the CC’s don’t finish the work we now have a solid corps of local hard-core trail volunteers who can.