Erosion Control

Amending the Soil

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Credit: W. JAMES CONSTRUCTION CO.
Earth has “amazing self-healing properties,” notes Barry Cook, a partner with Northwest Hydro-Mulchers.

“I’ve heard it explained a lot like a cut on a human arm. If you ignore it, chances are it will get infected and the issues will get complicated. If you clean it and treat it with some type of antibiotic, chances are it’s going to heal cleanly and without a lot of evidence of there being an issue.

“The same thing with earth,” adds Cook. “If we totally disturb a site, we have to do something other than throw on wood fiber mulch and some type of petroleum-based fertilizer. If we can do something that will improve and enhance the soil profile, which is where everything starts, then when we get down the road, we will have created an environment that’s going to support what we all try to achieve with hydroseeding or our erosion control BMPs [best management practices].”

Case in point: Beginning in 2013 and continuing through 2014, the US Army Corps of Engineers constructed a new setback levee to replace an eroded section of the Steamboat Slough levee in Cathlamet, WA, at a 68-acre site along the Columbia River.

Cook says the existing levee was the current shoreline of the Columbia River near a wildlife refuge for the Columbian white-tailed deer.

“The existing road that made up this levee along Steamboat Slough was beginning to fail, so the Corps of Engineers decided to create a setback levee as a protection for this natural area,” notes Cook.

The setback levee was constructed behind the old levee, and then channels were dug that created streams between the old and new levees. The J. E. McAmis company served as the contractor on the project.

The project’s goal is flood control and fish restoration. The construction of the setback levee restored tidal wetlands habitat. As a flood control measure, the new levee will protect the Columbian white-tailed deer and its habitat.

Following the work of the general contractor, Cook’s crew did the revegetation work in October 2014.

Because the soil profile on the impervious side of the levee was difficult to work with, Cook’s crew used PermaMatrix Biotic Soil Amendment from Sunmark Environmental Services. The product is applied hydraulically and is designed to reduce the impact and cost associated with replacing topsoil and compost. PermaMatrix combines carbon-based fiber, organics, microorganisms, beneficial fungi, water-holding materials, and other soil-like components to create a growing medium designed to be optimal for plant growth. It is designed to be effective in poor soils that need an organic additive and for slopes and channels where the organic content of the subsoil needs a significant boost.

The project was timed “seasonally to coincide with the typical annual precipitation, and it was coupled well with the temperature component that brought germination very quickly,” says Cook.

A combination of native grasses was chosen to revegetate the site. After applying the soil amendment, crews placed an erosion control layer of wood fiber mulch and tackifier over the PermaMatrix and seed.

“Whenever we use PermaMatrix, we use an erosion control component with it, whether it’s rolled erosion control for slope protection or a bonded fiber matrix application. We’ve done a project with Flexterra over the top of the PermaMatrix,” says Cook.

“We’ll put on a couple of inches of compost or use a compost topsoil blend and start putting on inches of product in order to achieve what we know intuitively to be better. It doesn’t take a rocket scientist to walk into your grandma’s backyard, kick her soil, and know whether or not it’s going to grow her tomatoes. The same thing occurs in highly disturbed construction sites or sites requiring some type of reclamation or restoration. Plants need some kind of help.”

Another critical factor was that the breach project-which entailed cuts in two places-had a specific timeline.

“Once the breach happened, the interior of this slough area would flood at high tide, and there were concerns that there would be complete inundation over the top of these elevated soil mounds that were hydroseeded,” says Cook. “The goal was to get everything done as quickly as possible. We had to seed those soil mounds early because of breach. We had to lay down the PermaMatrix on the impervious side of the levee, but we needed to wait for the construction process on that to be completed.”

Responding quickly to the needs of the general contractor’s tight deadline was one challenge. Another was access. Cook’s team mounted hydroseeding equipment on tracked vehicles for site access.

Germination was achieved in 14 days.

Cook favors PermaMatrix for its ability to “jump start” the soil. “While I can’t attribute 100% the speed of germination to the PermaMatrix application-because we all know that post-plant moisture and temperature is a huge component of how you get any kind of plant community established-we have seen that when we introduce seed to the soil surface and use a product like PermaMatrix, we can jump start the process.”

Cook is pleased with the results and shot time-stamped photos showing the consistent growth “as you would expect from a hydraulic application,” he says.

“Big Rock in Little Rock”
A 7-acre slope nicknamed “Big Rock in Little Rock” has had problems with vegetation establishment. The site is near an interchange that’s been under construction by the Arkansas State Highway and Transportation Department.

The slope, at the I-430 and I-630 interchange in Little Rock, AR, revealed a large rock that could not be blasted after it was cut.

Previous attempts to provide erosion control at the site have failed. Amy Mathews, territory manager for the state of Arkansas for Pennington Seed, was enlisted by the highway department to solve the problem after the other contractors had gone out of business.

“I took soil samples, then recommended a seed mix, fertilizer, amendments, and hydromulch to complete the job,” she says.

In September 2013, Mathews had visited the site following previous attempts to establish vegetation.

“The results were poor-the annual grass had matured and died,” she says. “Perennial grasses did not establish due to poor soil nutrients and low pH.”

It had been an area fraught with challenges for the longest time-first in seed establishment and then, once the solution was created, in applying that solution under trying conditions, notes Mathews.

Site challenges included poor or no germination with standard seeding practices of straw mulch, Bermuda, and annual rye. The site was seeded a second time with pine seeds and sweet gum seeds, again with minimal germination.

Gary Williamson, who handles stormwater management issues for the Arkansas State Highway and Transportation Department, had been researching hydromulch options and asked Mathews what could be done with hydromulch.

“After two years of no growth in Arkansas, I knew something had to be wrong with the soil,” says Mathews. “In two years, typically Arkansas soils would naturally reestablish vegetation-we are the “˜Natural State.'”

Mathews took soil samples, sending them to the University of Arkansas Agriculture Extension Service and to Profile Products’ PS3 soil analysis lab.

The pH was low at 4.3 and 5.1, and the soil was sandy loam with very little organic material.

“I used the information to verify the needs of the soil and recommend proper amending, knowing an obstacle was the steepness and length of the slope,” says Mathews. “Amending soil by broadcasting was not a choice. I chose soil amendments that could be applied with a hydroseeding machine.”

Profile Products’ NeutraLime Dry, a calcitic lime product, was used to get an immediate change of pH for germination. Profile Products’ JumpStart liquid formulation, which contains a soil penetration agent, humic acid, and more than 200 species of beneficial soil bacteria, was also used to get a quick germination, increase water-holding capacity, and enhance root growth and root mass, says Mathews.

Fertilizer was recommended by the soil test. Mathews opted for a 9-18-24 professional-use fertilizer by Pennington.

“I requested Koch Agronomic Services’ Uflexx with a slow-release nitrogen to extend the feeding of the seedlings,” adds Mathews.

She used the Profile Products PS3 software for a hydromulch verification. “Because of the slope length and grade, Flexterra was the obvious choice,” she says.

Seed choice is critical, Mathews points out.

“That is what will be there for the duration of the hillside,” she adds. “I specified a Pennington Fall Slopemaster seed mix, mixed specifically for Arkansas.” The mix is a combination of Sahara Bermuda, Mohawk Bermuda, MaxQ fescue, Pensacola bahia, durana clover, and a small amount of annual-less than 10%.

“It has both warm- and cool-season grasses for good erosion control year-round,” says Mathews. “This seed was premixed and enhanced with Myco Advantage and GermMax, which help the seed germinate and increase root growth. This reestablishes the natural microorganisms that are found in healthy soil.”

The successful approach was installed over two days in October 2014 by Nichols Erosion. Weaver-Bailey Contractors served as the general contractor.

The site’s location was a challenge. It was accessible only from the newly built off ramp, not yet open to traffic, but the rest of the area had high amounts of traffic, notes Dusty Nichols of Nichols Erosion.

That, and dealing with a very steep, long, and large slope of 2:1 created a challenging work environment.

“There was no way to spray from the top, which consisted of a wall of trees on hospital property,” says Mathews.

In addition to the woods behind the Baptist Health Medical Center, there was a large chain link fence without a gate at the top of the slope, making access impossible. All of the spraying had to be done from the bottom and from a large-enough machine to hit 200 feet, says Mathews. Nichols Erosion had such a machine: the Finn T330.

Watering was another challenge. “Although we wanted to spray earlier in the year, we held off to the fall after the summer heat and drought to give the seed the best probability to thrive with fall rains and cool weather, with that seed mix changed to the fall mix,” says Mathews.

The steepness of the slope and the low pH also was a challenge for liming, in that broadcasting pelletized lime is standard, she says.

“This was impossible to accomplish, so the pH was adjusted with Profile Products’ NeutraLime,” says Mathews. “This was put into the hydromulch slurry and sprayed with the seed, fertilizer, and Flexterra mulch, making a tough situation easier to handle.”

Winds were yet another problem.

“In the afternoon, the winds reduced the spray distance,” says Mathews. “Traffic was a challenge-the site was never shut down, but making sure traffic moves smoothly and safely around the work is always a concern.”

Mathews says Dusty Nichols’ expertise and experience was critical in the installation.

“Timing and correct mixing of the slurry to activate the tackifiers of Flexterra made the spraying successful,” she says. “He managed to reach all the way to the top of the slope early in the morning when the winds were light. Correct mixing and coverage of the slope was important to get a layer of mulch and seed that mimicked an erosion control blanket, conforming to the hillside.”

The job also required much patience for Nichols’ crew to get to the water site.

“The caravan consisted of a lead truck, a HydroSeeder, and a tail truck, which had to make one U-turn and navigate two clover leaves, an exit ramp, and a left turn to get to the hydrant to refill over and over,” says Mathews. “Each load required the same diligence. It was not as easy as “˜fill the tank up and spray.'”

While the primary objective of the project was to establish grass on the slope for erosion control, a secondary objective is aesthetics, Nichols notes.

“That rock has become quite a landmark in Little Rock,” he says. “Everybody is pretty sentimental about it. They want nice, green grass growing around it. They want a beautification project.”

Nichols’ advice to other contractors facing a similarly challenging situation: “Always do your homework, have a good plan, and have good equipment, and everything else will take care of itself.”

Wind Power
Southern California Edison (SCE)’s Tehachapi Renewable Transmission Project (TRTP) will deliver electricity from new wind farms in the Tehachapi area to SCE customers and the California transmission grid. The project incorporates new and upgraded electric transmission lines and substations between eastern Kern County and San Bernardino County to help meet California’s renewable energy goal of 33% by the year 2020.

Erosion control plans and stormwater pollution prevention plans (SWPPPs) play a critical role in the construction process.

W. James Construction of Escondido, CA, is serving as the hydroseeding contractor for SCE on its TRTP projects located in the Angeles National Forest. Warren James, the company president, notes that although his company has done major projects before, this project is being executed in a unique fashion; he credits SCE and PAR Electric for being able to merge the construction and restoration contractors’ tasks together to create a seamless transition into restoration activities.

W. James Construction is working on three links of four segments of the large transmission project: segments 6, 7, 8, and 11. Seeding efforts on segments 7 and 8 have entailed the company working with the restoration contractor in seeding for its needs.

“It’s the first time we’ve done that,” notes James. “Typically what happens is we’ll come through and stabilize for the construction contractor with SWPPP seeds, but what’s been happening is there’s been a break in the work where the restoration contractor has to come back and do some sort of a scarification process to put down their specialty seeds.”

For segments 7 and 8, the PAR Electric team came up with the idea to join the two tasks, putting down restoration seed during the required stabilization for the construction contractor.

“It’s bridging a gap,” says James. “I’m extremely happy, PAR Electric is extremely happy, and it’s working out for all parties right now.”

Overlap can be an issue in a contract, he notes. “The way it worked in the past is the construction contractor was only required to stabilize the site,” points out James. “What we would do is come stabilize the site with hydromulch, jute net, or whatever would be required. The problem is that the restoration contractor always has special timing. Usually it’s going to be the winter months.”

Every project on which James has worked is finished after winter, he says.

“There would be that gap in time from the end of winter all the way through summer until the next planting season when the sites are exposed,” he says. “That creates a stormwater liability for the utility, because the prime grading contractor would be off the hook, but then [the utility] is going to be on the hook for the stormwater compliance until the restoration contractor could even start. Then the restoration contractor would come back and essentially would have to pull up what we put down in order to get a clean slate to start their planting process.”

In this project, all involved parties came together on the last few links, acknowledging that was not the best approach, says James. “We were not doing ourselves any favors in the long run,” he adds.

The team from PAR Electric asked James, because his company was already going to be out at the site stabilizing and hydromulching, if he would be opposed to working with the restoration contractor in putting their seed in with his mix at their direction as part of his stabilization process.

“I said I was absolutely not opposed to that idea,” says James. “It’s a jump start for the restoration contractor. They don’t have to worry about reseeding and scarifying what we’ve already done.

“It’s worked pretty well,” he adds. “It’s the first time I’ve worked in conjunction with a restoration contractor, so it’s a new experience for me and our company, but it’s been a very enlightening experience.”

Given California’s drought, choosing the right seed mix was critical to the success of the project. James’ company is working with six different seed mixes for the restoration areas and one general SWPPP mix for everything else. The seeds-which are native plant seed collected within the region-are sourced from S & S Seeds.

James’ company specializes in remote and hard-to-access sites, which was a benefit to the project. The seed was applied with Bowie Hydro-Mulchers.

“A lot of transmission sites are remote,” James points out. “You couldn’t get a 3,000- or 4,000-gallon truck to probably 80 to 90% of the areas that we typically would have to stabilize. We either get there by helicopter or their extremely tight right-of-way roads where we put a small Hydro-Mulcher in the back of a 4 by 4 pickup and drive out to the sites.”

The company uses a standard application rate. Rates are calculated based on how many pounds per acre are needed for stormwater management purposes. W. James Construction then creates a base mix.

James says some 1,500 pounds of seed have been used on the links for the work on segments 7 and 8, which he says comprises an estimated 75-100 acres.

Contingency seed is ordered up front, says James. For example, if a site calls for 10 pounds, 12 pounds are ordered to provide a 2-pound buffer.

“The restoration contractor has the ability to dig into the contingency seed if they want extra square footage sprayed at the site,” says James. “Every site is different. It’s difficult in these environments. We don’t necessarily know what we’re getting into until we’re at the site. The acreage fluctuates and it’s hard to anticipate.”

Restoring Bowman’s Creek
In Wyoming County, PA, Adam Nordfors, president of Nordfors Environmental Design in northeast Pennsylvania, used biotechnical methods-which included seeding as a component-to stabilize banks and restore aquatic and terrestrial habitat along the upper portions of Bowman’s Creek.

The creek feeds into the Susquehanna River, a tributary of the Chesapeake Bay. Logging had occurred on the land in the late 1800s. Over the course of 12 years, the valley was almost entirely clearcut.

“Although the length of Bowman’s Creek is not that long, the upper watershed is in a heavily glaciated mountainous region where slopes are very steep for Pennsylvania; it’s a very narrow valley,” says Nordfors.

“We also have acid rain in this region with rain events as low as 3.5 pH. It’s an ongoing problem that is leading to degradation of the watershed and forest system as a whole, which of course affects stability of slopes and waterways. Considering the geological context of deep glacial till and degraded biological control, once a system like this starts to go, it’s very difficult to return back to something we would consider stable.”

Many factors have led to instability in the upper watershed. In 2006, flooding resulting from prolonged and heavy rains caused significant damage, eroding streambanks, taking down trees, and flooding the town at the end of the valley.

“Everyone felt this was a very devastating flood. Yet again, in 2011, Hurricane Irene hit and to everyone’s disbelief the damage was much worse than in 2006,” Nordfors notes.

The resulting damage was the tipping point on a significant tract of land owned by Douglas Ayers, a renowned local veterinarian and conservationist who owns a large animal hospital and specialty center and with friends started the nonprofit North Branch Land Trust and The Lands at Hillside Farms, a nonprofit sustainable-living initiative.

The 2006 hurricane took down a significant number of trees, exposing an alluvial floodplain at the bottom of the valley.

“Even with the freeze/thaw cycle, with no significant flooding other than annual spring flood and seasonal water fluctuation, the bank was sloughing off around three feet annually,” Nordfors points out.

Following the 2011 flood, the site was left completely devoid of trees and vegetation, with a sheer dropoff ranging from 6-9 feet to the creek.

“Dr. Ayers was interested in eventually doing remediation on all of his property, but this was the biggest fire to put out,” says Nordfors. “It was on the upstream portion of his property where the creek entered the land. Several years before, a landowner just upstream, with good intentions I’m sure, had straightened 1,200 feet of the creek to help protect his property.”

Typically, rivers have snaking patterns representative of a balance between slope, soil type, and water volume, “and physics dictate what that form can be. In this particular setting, a straightaway that long could never happen naturally, nor could the immediate watershed sustain such a form; something had to give,” he adds.

Therefore, the creek-straightening project created a large rifle in the river, with a 90-degree turn at the end.

“It was inevitable that this was going to carve through Dr. Ayers’ lowest and best field on his property,” says Nordfors. “Preserving this Appalachian farm while addressing the obvious need to begin rehabilitating the creek became our main goal.”

The project started with that 550-foot stretch.

“It is extremely rare for a private landowner to fund something like this, because cost is just prohibitive,” says Nordfors. “My work focuses on remediating degraded sites. I employ living materials to achieve engineering goals to the greatest extent possible, not only for their ability to capture energy, improve hydrology, and create habitat, but equally, if not more importantly, to reduce costs.”

In most watershed projects, large volumes of quarried stone, including its transportation and installation, take up whatever budget might be available, and that in itself becomes the project, Nordfors notes.

“While these installations often solve immediate problems on specific sites, they tend to have negative tertiary effects on the system as a whole, such as creating sites hostile to diverse plant and animal life as well as creating thermal pollution to adjacent water bodies,” he says.

“I believe there are better ways of designing. I create living streambanks-something that evolves and becomes increasingly stable over time, something that is part of a resilient system and has positive effects downstream, creating seed banks, and capturing and dissipating energy.”

For this portion of the project, says Nordfors, it was “unavoidable” that he would need to use some sort of armament on the corner, which came in the form of a single layer of large rocks of up to 8.5 tons, forming the toe.

“We made sure the bottom of this toe material was three and a half to four feet below the lowest point in the stream, or thalweg,” says Nordfors. “It’s estimated that in that last storm in 2011, we had three feet of active bed movement in the stream. A lot of the standard riprap wouldn’t work-it would be too unstable given the velocities we’re working with, assuming a storm of similar magnitude will happen again.

“Dr. Ayers brought me out because he understands that no matter what he asks me to do, he knows I will design and install something that is as inexpensive and as stable as possible while focusing on the greater ecological context-creating habitat and using native plants.”

That’s what Nordfors’ team did, using a joint planting technique with a single layer of large rock.

“Our slopes vary and were as low as we could possibly make them. At the upstream portion of the project, we had to meet up with an existing bank that was around 20%, so that portion does have layered rock for a short stretch that turns back into what is called a bank return, which is there to prevent flanking of the installation in any future major flood event,” says Nordfors.

The team installed several rootwad deflectors to further protect the initial part of the structure.

“At the base of this and from that point on, we used large toe material. The slope decreases as it continues. At its lowest point, it’s at 10% slope. We tried to adjust the radius of the corner as much as we could with the constraints of budget,” says Nordfors.

After the slopes were set and toe and bank material was in place, the team proceeded with “joint packing,” which Nordfors says is basically filling all voids between rocks with tamped soils.

The final step was to cultivate the soil and plant a mix of native seed from Ernst Conservation Seeds, which also was the source for some 4,000 willows and dogwood on the project. The seed was covered with local old hay.

The stream now has a more gentle turn, Nordfors says, adding that the toe is 80 feet out from where the bank had been previously cut.

“Our method is to observe and document the site rather than just look at a few aerial photographs and say, “˜This is what we’re going to do,'” says Nordfors. “We tried to find reference streams, but everything that was similar to this in Bowman’s or other regional creeks was equally destroyed in the flood, so a healthy reference stream wasn’t viable for us. We looked for the best places we could see that were still stable-what plants and soil communities were growing there, among other factors.”

The project began in October 2013. Surveying and design was completed in January 2014, following planning sessions and meetings with the Pennsylvania Department of Environmental Protection and the Natural Resources Conservation Service (NRCS).

“Our goal was to start work at the end of February. The winter was long and hard. There was so much snow on the site and so much ice in the creek that I had trouble finding a contractor willing to do the work,” says Nordfors.

“We would rather have heavy machinery onsite when the ground was frozen. We had to have living material in during the dormant period and had to avoid the trout spawning season-we had a deadline set by nature itself. Regardless of anything, the work had to be finished by April 1.”

Nordfors had to let go the first contractor for “dragging his feet.” That contractor was replaced with John Brdaric of Brdaric Excavating and Buck Mountain Quarry.

“They did an amazing job reconstructing the bank and adjusting the slopes,” says Nordfors. “The dozer did one full pass of the site and they said that should do it. I thought they were joking, but when I took my grades, they were right on. I could hardly believe it. The whole process, including laying the stone, took them just two weeks and two days. There was more than 2,000 tons of stone in the project, so it was very impressive.”

After that work was complete, the biotechnical team came in, did the joint planting, and also rehabilitated the farm field, planting pasture crops and constructing a riparian meadow ranging from 30-50 feet wide that transitions down into the slope.

Ernst offered a conservative estimate of 2 feet of growth on willows and from 8 inches to a foot of growth on the dogwood. A few willows have reached 4.5 feet.

“The dogwoods are a little bit slower, but they’re still doing well,” says Nordfors. “We have about an 85% success rate with the pole plantings, which exceeded what I had planned for.”

There were two challenges with the project. One was seed predation as a result of what Nordfors calls an “Alfred Hitchcock-sized flock of red-winged blackbirds that showed up” on the property. Deer also chewed away at the dogwood.

“Another interesting experience was inevitable: working at that time of year, the stream volume fluctuates wildly,” notes Nordfors. “As soon as the heavy equipment pulled out, the stone was laid, and our first round of joint planting was done, the creek rose four feet overnight and so the project got some action right away before we had any vegetation.”

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