Vegetating
Ski RunsBeautiful
Lake Tahoe straddles the California-Nevada border and is situated approximately
40 minutes from Reno, NV, and a little over three hours from San Francisco. Near
the north shore of Lake Tahoe, on the California side, sits the historic small
town of Truckee, home of the Northstar ski resort.
In
the spring of 2008, Northstar built four new ski runs and a ski lift, and Kelley
Erosion Control, based in Reno, was brought in to help revegetate affected
areas. Owner Kym Kelley describes the process:
“First
the loggers came through with mastication of the remaining tree stumps, then we
came in and broke up rocks and boulders. We didn’t want any rocks larger than
about 6 inches, but we also didn’t want to disturb the subsoil, so we had to
chisel down the boulders. Then the snowmaking guys came through, and we followed
right behind them. The snowmaking lines were all hydroseeded, each approximately
50 feet wide and 2,000 feet long. In areas where the soil had been turned, we
used soil amendments.”
Kelley
utilized a Finn T-400 HydroSeeder with a 4,000-gallon tank, in addition to a
smaller Finn T-90 with an 800-gallon tank, dragged by a bulldozer. “I wouldn’t
use anything other than a Finn,” she reports. “These are the most popular
machines, and the company takes really good care of us. Parts are shipped out
promptly. We get tons of mileage out of our equipment—we use the heck out of
it.” Finn offers leasing options, but Kelley owns all of her
HydroSeeders.
The
hydroseeding mixture she selected included:
- Biosol as a fertilizer, at
1,800 pounds per acre
- Kiwi Power, an organic
complex consisting of microorganisms and enzymes, humic acid, organic wetting
agents and cytokinins, and organic growth hormones, at 5 gallons per acre
- Mycorrhizae, fungi that help
roots absorb nutrients, at 60 pounds per acre
- Grass seed at 22 pounds per
acre
- Paper mulch at 2,000 pounds
per acre
- Tackifier at 150 pounds per
acre
“It
took about two to three months to treat about 50 acres; it was very
labor-intensive,” Kelley says. “In some areas, we were able to take some of the
logged trees and produced wood chips for mulch. That was the advantage of
following behind the loggers. The availability of these wood chips determined
what we used for mulch. Where the chips were not available, we applied
hydromulch.”
Her
work began in May 2008, and she reports that little rain fell at the time, which
proved advantageous. “We didn’t want too much rain, so the seed will sit
dormant. Germination will take place in the spring of 2009. The tackifier should
be sufficient for an active run, to keep everything in place.” She typically
uses about 120 pounds per acre of tackifier, but increased this application to
150 pounds per acre.
Kelley
is a big advocate of hydroseeding and sees its use increasing. “The entire
industry is increasing. People are really taking the environment seriously. The
‘green’ movement is definitely more in the forefront now. Hydroseeding tends to
be less expensive than other options, and it provides three important benefits:
erosion control, sediment control, and dust control. So you get a big bang for
the buck. One spray application solves three problems at
once.”
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Photo: Profile Products
The West Virginia Highway 47 cut revegetation project in Parkersburg |
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West
Virginia Highway 47 Cut
“In
15 years of working with hydraulic products, I’ve never encountered a more
challenging project,” says Stephen Zwilling of Profile Products LLC in Buffalo
Grove, IL. He’s referring to the 14-acre Highway 47 cut revegetation project in
Parkersburg, WV.
“There
have been many attempts over a number of years to establish vegetation here,” he
explains. “When the highway was originally built and the mountainside cut, there
wasn’t the erosion now found at the site.”
The
problem is that this piece of mountain adjacent to the highway is very steep and
very high, reaching as high as 425 feet above the pavement. In the past, the
state department of transportation (DOT) had tried various options, including
broadcast seeding and hydroseeding. They had considered the use of erosion
control blankets, but with nearly vertical, highly eroded slopes, it was
unlikely that blankets could even be installed. Building a large concrete
retaining wall was another option, but its multi-million-dollar price tag
effectively ruled out this hard-armor solution.
“None
of the previous attempts grew anything significant,” Zwilling says. “Eventually,
regulatory agencies got involved and put pressure on the highway department to
do something.” There was concern about potential rockslides, as well as concern
for the water quality of nearby creeks.
Marc
S. Theisen, vice president of Erosion Control Solutions with Profile Products,
explains that his firm was brought in to try to resolve the ongoing issues. He
found not only that the mountainside was eroding and “very inhospitable to
revegetation,” but also that access to the site was very challenging; so much
so, in fact, that the state had considered the use of a helicopter in its
hydroseeding efforts. Theisen explains that the overall slope of the hillside
was greater than a 45-degree angle, measuring about 0.75 horizontal to 1
vertical, with certain sections even steeper.
Yet
another problem popped up. Theisen and Zwilling both note that the soil in this
part of the country, as in much of the eastern US, tends to be somewhat acidic,
and officials at the West Virginia DOT naturally assumed that this Highway 47
cut was no exception. However, no soil sampling had been
done.
“You’d
be surprised,” Theisen says, “how often such projects proceed without any
agronomic soil testing. They’ll do all the geotechnical and sieve analysis tests
to keep the engineers happy, but they often fail to conduct any agronomic
testing.”
Ultimately,
a soil analysis was conducted, which set off several alarms. Most shocking was
the pH of the soil. Rather than being slightly acidic, the soil pH measured as
high as 10, which is highly alkaline. Zwilling notes that the department had
planned on adding lime-based soil amendments, thinking that perhaps the presumed
acidity of the soil was contributing to the difficulty in obtaining viable
vegetation.
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Photo: Profile Products
The mountainside was eroding and was very "inhospitable to revegatation." |
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Photo: Terra Novo
The Adirondack slopes in Warren County, NY |
Zwilling
is not surprised that a soil sample had not previously been taken. He speaks to
and works with engineering firms routinely and finds that perhaps 95% of the
time, a soil test is not conducted prior to breaking ground. “But these are very
inexpensive,” he says, “costing perhaps $50 or less, rising to around $200 if
immediate or more extensive analyses are needed. When I tell them the low cost
of soil tests, and note that pH is the second-most-critical consideration (after
water) for ensuring effective nutrient uptake and successful establishment of
vegetation, I find that they are appreciative, and many people are changing
their ways. For example, both the West Virginia DOT and the South Carolina DOT
now require that soil be tested.”
Zwilling
emphasizes, “When plants are trying to establish themselves, everything needs to
be in balance so immature plants can establish their root systems and grow.” And
the pH level is an important part of the equation. Ideally, soil pH should fall
within a range of 6.3 to 7.3 for healthy plant growth.
Theisen
notes that once the pH problem was identified, he knew that it had to be lowered
substantially. Another question that remained was what kind of seed mix to use.
Drawing on the combined experience of the West Virginia DOT; the Department of
Natural Resources (with its experience in difficult mine reclamation projects);
Profile Products’ in-house agronomists; and its local contractor, Penn Line
Service, an interesting seed mix was developed. Several different seed types
were utilized, including orchard grass, birdsfoot trefoil, redtop grass,
switchgrass, perennial rye, and alsike clover. Perhaps the most surprising part
of the mix, however, was the inclusion of Bermuda grass.
Bermuda
grass is rarely used in that part of the country, Theisen explains, because it
favors a warmer climate. It is also not often used on such steep slopes.
Zwilling made the call to include Bermuda grass, however, because at the time of
application, they were entering a hotter part of the year and Bermuda is more
drought-resistant than many other grasses. Zwilling was concerned that there
might not be sufficient rainfall to nurture the growth of the predominantly
cool-season seed mix. He also had another reason to use Bermuda grass. “It sends
out runners and creeps all over the place,” he says. “Plus, it fills in areas.
If I had to do the project all over again, I’d use an even higher proportion of
Bermuda grass in the mix.” Theisen adds that the Bermuda grass is now gradually
cascading down the cliffs and creating an erosion-resistant root
mass.
Another
issue that frequently arises, according to Zwilling, is the organic content in
the soil, which typically comes from decomposed plant material. “You need at
least 2 to 3% organic matter in the soil for plants to thrive. This is
typically, but not always, found in most topsoil. Farmers know that if you have
good topsoil, you have good crops.” He adds, “If the organic matter content is
too low, you need to amend the soil. For example, you can bring in topsoil or
compost. In addition, we now have new additives that can be mixed into the
hydraulic slurry to significantly increase the organic
composition.”
In
this specific project, the organic content was about 4%, but certain areas were
devoid of organic content. “You can apply Flexterra FGM over shale,” Zwilling
explains, “but you need some soil present in order to achieve plant growth. In
this project, the soil was crummy, there were lots of rocks, the pH was out of
balance, and there were really steep slopes. It was hard to get infiltration,
since with slopes so steep, everything just runs off.”
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Photo: Western States Reclamation
Hoses were used to hydroseed the Piceance Basin in western Colorado. |
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Photo: Western States Reclamation
After hydroseeding with organic fertilizer and a guar tackifier, a modified-matrix flexible growth medium mulch is used at the Colorado site. |
Because
of these problems and the lack of viable alternatives, the decision was made to
proceed with a site-specific mode of hydroseeding, but another problem had to be
addressed. Typical hydroseeding machines can spray a distance of nearly 200
feet, but the slopes involved ranged from about 150 feet high to more than 400
feet high. For such distances, Zwilling says, “You need to apply the mixture
aerially or use a hose. We chose to use a hose and ran it up the slope. The
workers would climb up the hillside, and the machine was powerful enough to
spray through the hose.” The Pennsylvania–based contractor, Penn Line Service,
used a 3,300-gallon Finn HydroSeeder for the application.
The
difficult project had to be completed in steps. Initially, elemental sulfur,
powdered iron sulfate, and gypsum were hydraulically applied to reduce the soil
pH, and this mixture required time to activate. Penn Line waited approximately
two weeks before proceeding with the actual hydroseeding. In addition, a
combination of Super-Bio microbes, Profile JumpStart 5, and a 15-30-5 fertilizer
was applied to build an effective organic base for seed
establishment.
Zwilling
points out that, partly as a result of the difficulties encountered in this
project, a new soil neutralizer has been developed—Aqua-pHix. It is intended for
soil with a pH greater than about 7.3 and can be applied to buffer the soil. In
contrast to this Highway 47 project in which two weeks were needed to alter the
pH, with Aqua-pHix, “You simply pretreat with it, allow 1 to 2 hours’ time, then
apply the mulch/seed mix. It essentially adjusts the pH in just a few days with
the effect lasting for perhaps 18 to 20 weeks,” he explains. A related soil
conditioner from Profile Products, NeutraLime, is available in cases where the
pH is too low, less than about 6.3.
Another
important decision in the project was the selection of appropriate mulch.
Zwilling explains that on simpler projects, a basic wood and paper hydraulic
mulch may be sufficient. “These are OK for limited erosion control, they’re
inexpensive, and they work well for flat areas.” But for this project, a
different formulation was needed.
Zwilling
elected to use Flexterra FGM, a flexible growth medium that immediately bonds to
the soil. Flexterra combines “thermally refined” wood fibers with crimped
manmade fibers and other additives to produce an interlocking matrix with
water-absorbing cavities that enhance germination and reduce soil
loss.
“It
maintains its strength even in wet conditions,” Zwilling says. “It will stick to
a vertical slope—it locks on. You spray it on, it sets up and cures, and soil
particles don’t move. Flexterra retains up to 1,500% of its weight in moisture
and is the only hydraulically applied product that doesn’t require an extensive
curing time. If it rains, or something blows in, Flexterra will stay in place.
Most other products would just wash away.”
Flexterra,
which comes in 50-pound bags, was applied at a rate of 4,000 pounds per acre on
these challenging slopes. “We were essentially painting on a blanket over the
rock and soil,” says Zwilling. “But we applied the hydroseeding mixture in
stages, in case of bad weather.” Although this product resists washing off
better than others, in a significant rain event, some of the product will
ultimately wash away. He stresses that Flexterra is not designed for areas of
concentrated water flow, as in channels or roadside ditches. Its primary use is
for slope stabilization.
He
adds that paddle-agitation hydroseeding machines are needed in order to use
spray-on blanket products to keep the highly viscous slurries in suspension. A
jet agitation unit is unable to handle thick slurry, he explains, and Flexterra
is a very thick mixture. He also prefers bigger hydroseeding machines on large
projects, because “they have more power, more room for the mix, can cover a
larger area, and are simply more efficient. You don’t need to reload the tank as
much.”
The
initial proposal for the Highway 47 project was submitted in April 2006, but
because of funding and timing issues, work didn’t begin until May 2007. From the
start, everyone involved understood that there were some inherent limitations.
“Nothing will grow on bare rock, so the area will never be fully vegetated,”
Zwilling says. But today he is proud to be able to claim, “Where there’s soil,
there’s now vegetation. Nothing had ever grown here before. Rockslides cannot be
totally prevented, but the risk of a dangerous rockslide has now been
minimized.” Theisen adds, “It doesn’t look like a golf course—we knew that it
wouldn’t—but the amount of cover is significantly greater than before, and it is
expanding, and the soil is stabilizing.”
Eroding
Adirondack Slopes
In
July 2008, the New York’s Warren County Soil and Water Conservation District
took action to correct a problem that had been lingering for many years. Within
the district lies the town of Warrensburg, NY,
located within the rocky terrain of the Adirondack Parkway. Slopes had long been
eroding into the Upper Hudson River watershed, which is a pristine watershed
utilized for drinking water and recreation. For years, in order to save money,
Warren County had been using a standard guar tackifier, along with fiber, to try
to stabilize the area’s slopes. Results were less than optimal, and finally, the
Soil and Water Conservation District, tired of repeatedly having to go in and
reseed as a result of erosion from heavy rainfalls, took
action.
The
Bakersfield, CA, company Terra Novo had previously discussed with the district
the use of its erosion control product EarthGuard Fiber Matrix. The county
decided to try EarthGuard on a test patch of slope to compare with the guar
tackifier already in use.
Brian
Foster of Terra Novo describes EarthGuard as a polymer stabilizer fiber matrix,
which is a spray-on erosion control product “designed to work directly with soil
to maintain its stability by both preserving existing soil structure and
flocculating fine sediment being dislodged by stormwater or wind. Unlike bonded
fiber matrices and other copolymers, it doesn’t harden to create a false
barrier, which prevents water from entering the soil and seeds from
germinating.” EarthGuard can be applied by itself for rapid dust and erosion
control, or with a seed mix to achieve quick vegetation in difficult
environments.
In
the test patch, the EarthGuard was applied next to the guar/fiber mixture on a
rocky and slightly eroded slope. No special slope preparation was undertaken.
The district used a Finn T-90 HydroSeeder to spray a combination of seed, mulch,
and water onto the bare soil, and Foster reports that within 2 to 3 weeks, new
grass was emerging to stabilize the soil. For steep slopes, such as those
encountered in Warrensburg, the recommended application is 10 gallons of
EarthGuard, teamed with 3,000 pounds of paper mulch, per acre. A flatter
environment may be successfully treated with half of these
amounts.
The
Soil and Water Conservation District was impressed with the results. The day
following the EarthGuard application, approximately 4 inches of rain fell, with
a total of some 10.5 inches of rain over a 19-day period. Foster notes that the
EarthGuard Fiber Matrix provided effective erosion control, in addition to the
grass already sprouting. On the guar/fiber side, there was less plant growth and
significant erosion.
Within
two months following application, a whopping 20 inches of rain had fallen. The
slopes treated with EarthGuard remained stabilized and had achieved full
seasonal growth. On the other hand, the guar/fiber slopes suffered significant
damage and will need to be regraded and reseeded.
According
to Foster, “Standard tackifiers—such as guar, PAM, and psyllium—do not have the
strength to stabilize slopes through long and heavy rain events over an extended
period of time. Their effectiveness typically erodes away before a seed is able
to successfully germinate and establish a root mass and soil cover sufficient to
provide effective erosion control on its own.”
Jim
Lieberum, water resources specialist with the Warren County Soil and Water
Conservation District, says, “I was very impressed with how well EarthGuard held
up with all the rain we received the day after application. It saved us time and
money not having to revisit the slope.”
Oil
and Gas Drilling Reclamation
Western
Colorado is oil and gas country, and the region’s Piceance (pronounced
PEE-awnts) Basin may well contain the nation’s largest natural gas reserve. A
decade ago, it was estimated that the 6,000-square-mile Piceance Basin may
contain 30 trillion cubic feet of natural gas, but some current estimates reach
as high as 300 trillion cubic feet.
The
town of Parachute, CO, lies in the approximate epicenter of the basin and that’s
where Colby Reid, reclamation manager for Western States Reclamation, has been
working lately.
With
such mammoth reserves, the basin is home to thousands of wells, with hundreds
added annually. It is Reid’s job to revegetate the area surrounding new wells.
It’s generally a two-step process. “First,” he explains, “the gas company will
lay down the road. As soon as the road is pushed in, we’re there to seed the
topsoil and the roadside. Then, after the drilling pad is put in—hole drilled
and piping put in—we’re in the next day. The gas company makes the pad a bit
smaller and contours it, then we go in and do the final
seeding.”
These
“pads” and their surrounding area total about 5 to 7 acres each and are located
on an assortment of private land, Bureau of Land Management land, and Forest
Service land. They range from an elevation of 5,000 feet to as high as 9,000
feet.
Reid
estimates that about 70% of his revegetation efforts in this area involve
hydroseeding, applying varying seed mixes of grasses and shrubs. He treats the
area around the drilling pads as well as the roads leading into the pads; the
work is not easy. “This is a harsh environment,” he says, “and it typically
takes about a year to get any vegetation established. We have to contend with
rain, (or lack thereof) and wind, and weed control as well.” He is in the area
frequently because of his extensive reclamation work and is able to periodically
check on previous applications, but reports little need for post-treatment
touch-up work.
His
applications occur in two phases. Initially, he hydroseeds with organic
fertilizer and a guar tackifier together with the seed load. Then, about 24
hours later, he follows this with a modified-matrix flexible growth medium
mulch. He uses 50-pound bags of Flexterra, applying about 3,500 pounds per acre,
using two coats from two different directions to avoid a “shadowing” effect. He
applies this mulch well after seeding, he explains, because “out West, it is too
dry to combine all of this in a single hydroseeding application. The seed would
just get caught up in the mulch.”
Reid
utilizes two types of hydroseeding machines. He has a Finn 3,300-gallon
HydroSeeder and two new Finn Titan 4,000-gallon units, all of which use paddle
agitation. “Jet agitation is more for smaller machines,” he
notes.
He
uses hydroseeding cannons to spray up to about 200 feet, but beyond this, he has
to use hoses, often 200 to 300 feet in length. “We do a lot of hose work,” he
explains.
Although
hydroseeding is his most common treatment of choice, he also uses erosion
control blankets, employs a fair amount of drill seeding, and, occasionally,
uses straw/hay mulch rather than a hydromulch slurry. “If the terrain is flat
enough, I’ll drill-seed,” he says. “However, if it is too steep or too remote,
I’ll hydroseed.”
In
contrast to many other revegetation projects around the country, Reid finds that
in most of the areas he works, a soil analysis has been done. The pH tends to
come up a little alkaline, but not enough to require soil
amendments.
Because
of the demanding environment in which he works, Reid finds that his hydroseeding
work remains pretty stable, perhaps increasing a bit due to new wells being
drilled.