There’s a lot to be said for an erosion control technique that covers large, inaccessible areas with mulch and seed, and costs less than sod.
Hydroseeding provides immediate protection from surface erosion due to water and wind on bare slopes and disturbed soil areas. It initially reduces sediment generation by 70–80%, according to some estimates. Hydroseeding also speeds germination and vegetation establishment for long-term erosion control.
Shot from a high-pressure hose or spray gun, the hydroseed mixture travels farther than seed and water do alone. It’s usually used on areas larger than 0.5 acre, according to the California Department of Transportation (Caltrans), and is less efficient on smaller ones. The applicator shouldn’t be directed at one location for too long or the slurry itself can cause erosion.
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Hydromulch materials may be made from wood chips, natural agricultural fibers, newsprint, corrugated cardboard, or synthetic poly-based fibers. The mulch resists wind and water erosion, creates a blanket that protects the seed, retains soil moisture to improve germination, and provides nutrients for vegetation establishment. The length of the mulch fiber is key to its holding power.
The site and weather conditions determine the hydroseed mix. Soils that are compacted, nutrient-depleted, or poorly draining can be improved. Just about any amendment can be incorporated into the mix, including fertilizers, lime, gypsum, sludge, humus, growth stimulators, fungicides, inoculants, surfactants, and local topsoils.
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Slopes of any steepness and length benefit from the addition of a tackifier or binder to the hydroseeding mix. These glues may be powdered or granular and include guar, psyllium, pitch, rosin, and polymer. They help anchor the blanket to the soil and withstand wind and water erosion, even on steep slopes.
A caution for operators: The higher application rates required for steeper slopes may inhibit germination of seed and establishment of long-term vegetation, according to Caltrans.
The weather is the variable factor. In hot and dry areas, spraying water on the ground before hydroseeding will lower the soil temperature, and it provides a good base for the mixture.
Rain will ruin a good hydroseeding job if it occurs while the mix is being applied and before it cures, but the job requires rainfall, or failing that, irrigation, for the vegetation to establish. When there isn’t enough time in the season for vegetation to become established, a soil binder or tackifier added to the hydroseed mixture helps retain moisture in the soil.
When heat, rain, or wind are a problem, a bonded fiber matrix (BFM)—a mulch with fibers that are long enough to intertwine and a large amount of a polymer tackifier—may be a much better choice than a simple mulch. A BFM helps to lock the soil in place until the root system of the vegetation can hold it in place permanently.
The seed mix in the hydromulch depends on the area to be treated. In many areas, government contracts call for native seed, which varies from grass seed to native wildflowers and shrubs. The time between the loading of the seed in the tank and the emptying of the tank should not exceed 30 minutes, according to the Government of Michigan website.
PHOTOS: QUALITY HYDROSEEDING & RESTORATION
Silver Lake Village
The town of Bartlesville, 47 miles north of Tulsa, OK, is bisected into east and west by the slow-flowing Caney River. It’s a university town, home to both Oklahoma Wesleyan and Rogers State universities. The population is close to 37,000.
On the east side of town, not far from the river, a new retail and multifamily housing development is rising on Silver Lake Road. The first phase of the two-phase project consists of 85,000 square feet of development built on 15 acres of previously wooded land.
Semper Fi Hydroseed & Erosion Control, owned by former Marine Clint Bates, used a C120 gooseneck hydroseeding machine from Epic Manufacturing in Greenwood, DE, to revegetate the front and the back of the site to control erosion after the construction was completed.
Bates founded Semper Fi in 2017 as an offshoot of a lawncare company he founded in 1998. He began hydroseeding in 2006. The company works primarily on large commercial and industrial projects, especially around streams and creeks. As a former Marine, he employs veterans whenever he can.
“I like hiring vets over civilians,” he says. “We work well together and we speak the same language.” He donates 3% of the company’s revenue to suicide-prevention programs for vets.
Epic’s C120 gooseneck hydroseeding machine is “combat ready,” he says. “It has a gear drive pump and everything else. Epic also has A-plus customer service.”
The machine holds up to a full day’s worth of mulch and materials, says Jeff Clouser, president of Epic. In addition, approximately 25% of the load of the trailer is transferred to the payload capacity of the tow vehicle, which improves stability and reduces wear and tear on the axles and tires of the trailer.
The C120 can be configured as a skid unit, and because it has a modular design, it also can be configured in different ways according to how it will be used. It has a 1,000-gallon stainless steel tank, which prevents tank corrosion.
Its load-sensing, pressure-compensating hydraulic system gives the machine power when it’s needed and fuel efficiency when power isn’t needed. The hydraulically driven paddle agitation system allows the paddles to slow down and still maintain maximum spray performance, and the paddle shaft/bearing assembly design eliminates shaft seals that are prone to leaking.
The gear pump can spray as far as a centrifugal pump through the turret gun, according to Epic. It also can pump through 600 to 800 feet of hose and has pumped through double that length. The hydraulically driven spray pump is controlled by a speed control valve that eliminates the need for clutches, belts, chains, and pulleys.
The C120’s flush tank provides 60 gallons of fresh water for flushing the pump and hoses between tank loads at the end of the day, and the bearings are oversized and require greasing only every 250 hours or once a year.
Semper Fi hydroseeded 500,000 acres in approximately three weeks in August 2017. The contractor, KSL Dirtworks in Bartlesville, prepared the soil.
Semper Fi used 100% wood mulch, additives including soil conditioners and a tackifier, and seed, at a rate of approximately 2,000 pounds per acre. The water came from onsite.
While the specifications for the front of the building and other focal areas called for a good Bermuda grass, Bates used his own supply of the superior Riviera Bermuda grass. It’s slow-growing but more visually appealing, he says.
Behind the building, a flood control runoff pond with slopes from 2.5:1 to 3:1 holds water for a week or two after it rains. The specs called for a common Bermuda grass there, but Bates suggested adding some browntop millet.
“It’s ugly,” he says, “but it germinates quickly and establishes a root system quickly, so it provides faster coverage. Rooted areas optimize erosion control.”
Semper Fi Hydroseed & Erosion Control crews also used products from Profile Products, including JumpStart, which contains soil-penetration agents, humic acid, and more than 200 species of beneficial soil bacteria, and AquaGel, a co-polymer gel that holds up to 400 times its weight in water to retain moisture in the soil.
The company also experimented with ProGanics Biotic Soil Media on an acre of land. “It’s a new product by Profile,” says Bates. “It did really well.”
The site was busy with moving heavy equipment as well as multiple contractors, but it was secure, says Bates. “We have hard hats and reflective uniforms. There was mutual respect.”
The area received a lot of rain in August, which was a double-edged sword. On rainy days, crews couldn’t work and Bates was afraid the sprayed areas would wash away, but the weather ultimately worked to their benefit, he says.
“We had several inches of rain in a short period of time on several different occasions,” he says. “Seven to 10 days after we shot, we were starting to see sprouts of Bermuda, and they’re starting to spread. The site still has to be watered, though.
“We’re very pleased with the outcome, and the contractor was extremely happy, too.”
State Route 58
When Cynthia Poundstone, who owns and operates Quality Hydroseeding and Restoration in Ramona, CA, with her husband Ron, says that she takes jobs other people don’t want to do, she means it.
Between the fall of 2016 and August 2017, Quality hydroseeded along State Route 58 in the high desert of southern California as part of a Caltrans project. The project realigned and widened a 9-mile section of the former two-lane highway to a four-lane expressway at Hinkley, a major artery between Los Angeles and Las Vegas. Elevations in the high desert range from 2,310 to 3,110 feet.
“It had the most extreme conditions I’ve ever worked in,” she says. “We were fighting Mother Nature every day.”
In the winter, it was so cold that water froze inside the hydroseeding tank overnight, and the crew had to use a propane burner to thaw it in the mornings. In the summer, the temperatures went up to 110°, and the humidity was so high that it was hard to breathe.
“My guys had to work split shifts,” she says. “They went back to the air-conditioned motel in the afternoon and worked into the evening hours.”
It was windy all the time. On April Fool’s Day, a 100-year windstorm blew through with winds up to 120 mph and displaced some of the areas of hydroseed.
Cynthia began driving trucks on her parents’ farm in Minnesota when she was small, she says. “That was my experience getting involved with hydroseeding. Since 1980, I’ve worked on all kinds of hydroseeding machines. I did everything in the field.”
Cynthia and Ron’s son Jesse is the operations manager and an operating engineer. Their daughter Christine has worked in the office and is now working in the field as a union laborer.
Quality Hydroseeding and Restoration used its new Finn T330 HydroSeeder, which can be used for fiber mulching, straw tacking, and fertilizing as well as for hydroseeding. The T330 has a 3,000-gallon working capacity tank and comes with several features that improve efficiency and performance.
“It’s our first new truck in 37 years,” says Cynthia. “It was like winning the lotto.”
Ron Poundstone says the tank has an air flush to flush out hoses and a remote control for the engine speed and the pump. “It’s very convenient when running hoses. You can run the hose to a backyard and turn on the remote without having to run back to the HydroSeeder.”
The T330 allows more efficient loading and less spillage of the slurry, as well as the complete mixing of the slurry without the use of the pump, according to Finn. It provides faster slurry discharge over a greater distance and an improved rear sweeping pattern. It also has a pivoting hose reel that enables curbside, 45-degree, and rear hose discharge. In addition, it improves operator accessibility, comfort, and convenience.
Caltrans engineered, designed, and funded the project with supplemental funds from the federal government, and also specified the job. Skanska USA (a division of the international project development and construction group Skanska) and civil contractor Teichert Construction are building the road as a joint venture.
“Skanska is top-of-the-line to work with,” says Cynthia. “We work very well together.”
Quality Hydroseeding first applied a soil binder to stabilize the soils and for dust control. Crews used M-Binder tackifier during the construction of 13 detention basins on approximately 50 acres along the new section of road. Each detention basin is the size of a football field, with 2:1 slopes and a medium clay soil.
M-Binder is made from the outer coating of Plantago seeds ground into a powder, which becomes sticky when it’s wet. “Caltrans always wants the dust covered,” says Cynthia. “It’s a nice cover.”
Skanska did the soil prep for the hydroseeding. “On most of the areas of hard soil, they used a piece of equipment with a big roller with spikes called a sheepsfoot roller,” she notes. “It makes indentations in the soil. It’s good for hydroseeding and germination.”
In November 2016, Quality got the go-ahead to start hydroseeding 300 acres. Skanska provided the water from a drop truck. Quality hydroseeded the 13 detention basins as well as the north and south sides of the new 9-mile section of road. For 90% of the job, Quality used wood fiber mulch from Fiber Marketing International.
At the end, crews used Profile Products’ ProMatrix Engineered Fiber Matrix (EFM). They added a tackifier, emulsions, and a high desert native seed mix of shrubs, flowers, and grasses from S & S Seeds in Carpinteria, CA. They used no soil amendments. They spread approximately two loads of the mix per acre using the gun on top of the truck.
Near the end of the project, Caltrans added in some additional seeding on the contractor’s main staging area and the old SR-58, which took Quality Hydroseeding right up to the deadline.
“We just had to keep up,” says Cynthia. “We couldn’t have anyone working less than 100% all the time. Toward the very end of the job, a full moon came up and I had three guys working the night shift. I have a great crew.”
Most Caltrans hydroseeding jobs don’t need to be irrigated, she says. “Mother Nature is what brings in the vegetation. Some species are coming in from last fall. Within a year and a half or so, we’ll be able to see the fruits of our labor.”
Stoney Creek Erosion Control Wetland
The Thames River near London, ON, has flooded severely for more than 200 years, records beginning in 1791 show. The worst flooding was in 1937, when the water rose almost 30 feet.
Since the 1950s, dikes and dams have kept the city, on the north branch of the Thames, safe. However, in 2007, a city-commissioned report showed that rainfall intensity and frequency had increased in the Thames watershed in the past decades and that both intensity and frequency were likely to continue because of climate change.
To make matters worse, one of London’s fastest-growing residential areas lies in the Stoney Creek watershed, where the eroding Stoney Creek flows into the Thames.
The city developed a flood-risk reduction strategy that included planning for both climate change and future growth in the low-lying area. It restored a 1.8-kilometer stretch of Stoney Creek and created a 3.5-hectare erosion control wetland adjacent to the creek.
The engineered wetland covers approximately 20 acres of sandy, rocky subsoil. It contains a streamway, Stoney Creek Channel, which connects a series of four large stormwater detention ponds. The ponds have 3:1 slopes approximately 20–30 feet long.
The system retains stormwater to control flooding and to minimize erosion in the downstream reaches of Stoney Creek. The design includes habitat features such as marshes, turtle hibernacula, sunning sites, and dead standing timber.
JK Landscape in London was awarded the contract to hydroseed the ponds. The company does a great deal of water and stormwater management, says John Kochanowski, the owner of JK Landscape and the site coordinator for the landscape crew.
JK Landscape used Bowie Industries’ Imperial 3000 Hydro-Mulcher. The company, in Bowie, TX, is a fully integrated manufacturer, says vice president Dean Myers. Bowie performs almost all the functions of manufacturing its hydroseeding machines, from machining to fabrication, which allows its equipment to be welded together instead of bolted.
One advantage of the Imperial 3000 is its quick loading, mixing, and spraying times. Its three full-length agitators and patented system for shredding bales of mulch allow the machine to spread more mix on the ground in less time, for more cycles per day.
The design is basic for easy maintenance: It has straight plumbing to prevent the mulch from clogging, and if one part breaks down in the field, it usually can be repaired with commonly available components.
Funding for the wetland project was provided by the Ontario Ministry of Agriculture, Food and Rural Affairs and by Ontario Power Generation. Bre-Ex Ltd., a construction company in London, built the ponds and the channel.
JK Landscape did some fine grading before beginning the hydroseeding. Crews spread a mix of Flexterra High-Performance Flexible Growth Medium from Profile Products, a general 8-32-16 fertilizer, and a native seed mix. They used water from the channel and the ponds.
They used 4,500 pounds per acre of Flexterra. “Flexterra was an excellent choice,” says Kochanowski. “We encountered some drought. It held the ground until nature could take its course.”
All the seeds were from Quality Seeds in Vaughan, ON. “The tender forms provide the mixes,” says Kochanowski. “We special-ordered the seeds from Quality. We have a long relationship with them. Cathy [Cathy Wall, the product manager] is fantastic to work with.”
JK Landscape used annual rye as a cover crop to stabilize the ground quickly and approximately 23–25 kilograms of native seeds per hectare. The area is seeded and planted with native seeds and plants to enhance the environment and bring wildlife back, he says.
The hydroseeding job took about two construction seasons for a total of approximately eight months. Work began in the fall, started back up again in the spring, and finished in the summer.
The project went very well, says Kochanowski. The only challenge was access to the ponds.
“With this particular project, access was an issue. The truck wasn’t able to get close because there was farmland we couldn’t drive through. Without the power of the machine, we wouldn’t have been able to pump the Flexterra and the other materials far enough. It impressed me that we could pump so far—about 300 feet.”