Issaquah Highlands is no ordinary housing subdivision.
The project, a 700-acre housing development located in Issaquah, WA, will boast single-family homes, condominiums, fire stations, police stations, and schools once construction crews complete it sometime near 2012.
But Paulo Da Cruz isn’t focused on these amenities. He’s interested in something far less upscale: the construction site’s several steep slopes.
Da Cruz is president of Redmond, WA–based Northwest Erosion Control. The developers of Issaquah Highlands have hired his firm to keep erosion in check during the 10 years of construction it’ll take to build the community. For Da Cruz, that means somehow keeping stormwater from sending soil and debris down the development’s many high slopes.
“This is such a big project, and there are so many slopes for us to deal with,” Da Cruz says. “Basically, we’re dealing with an entire city being built on a hill here.”
To tackle this challenge, Da Cruz is turning to solutions involving vegetation, specifically to bonded fiber matrix. Da Cruz and his workers trail the development’s builders and contractors, applying vegetation to the slopes after construction vehicles have cleared them. This leaves the construction area dotted not with bare dirt—an invitation for future erosion problems—but with full and lush green areas.
Da Cruz has been providing this erosion control service for four years now and expects his company to do so until the 10-year building project is complete. “This is a very challenging project,” he notes. “All those steep slopes can present problems. The bonded fiber matrix, though, is a good solution. It [allows for] a good root system that really digs in there. It provides a lot of stability.”
Da Cruz isn’t the only contractor turning to vegetation as a means of combating erosion. Municipalities, highway departments, and housing developers are more frequently choosing this “soft armor” solution. The reasons? Vegetation is aesthetically pleasing. It’s hardy. And it’s permanent.
It’s little surprise, then, to manufacturers that vegetation—seeds, mulch, and soil enhancements—are becoming a tool of choice for contractors.
“We’ve definitely seen a growth in popularity for vegetation,” says Judy Allmon of Belton, MO–based Critical Site Products. “There are a lot of regulations driving this. If you are building a new Lowe’s or some other kind of commercial development, it helps to be using bioremediation products such as native plants or some other kind of vegetation.”
Building a New City
When Da Cruz and his company took on the erosion control work at Issaquah Highlands, they knew they’d be working on a housing development unlike any they’d ever seen. This project was to be a true master-planned community.
When completed in 2012, Issaquah Highlands will include 3,250 homes, 1,500 acres of permanent open space, and 425,000 square feet of retail venues. This doesn’t even include the schools and municipal services.
For Da Cruz, it was just too intriguing of an opportunity to pass up. “It’s a challenging project but an interesting one, too,” he says. “It was a chance to work with a number of different products spread out over a large, varied area.”
Although Da Cruz is relying on bonded fiber matrix (BFM) to combat erosion on the development’s many steep slopes, he is using wood fiber mulch on the development’s less challenging flatter areas. The wood fiber mulch is made up of shredded wood that has been heated, dried, and injected with guar tackifiers.
For the slopes, Da Cruz has turned to BFM, a hydraulically applied, continuous layer of long fiber strands held together by water-resistant bonding agents. BFM does not form a hard, waterproof crust, however, and this is important: Such a crust could prevent future plant growth. The matrix also biodegrades into material that helps foster the growth of vegetation.
Da Cruz and his employees had to take several factors into consideration when considering how to fight erosion on the Highlands site. There’s the Seattle-area climate to worry about, for instance, and the type of soil. Because of this, Da Cruz chose a specific seed mix to help boost the erosion-fighting properties of the BFM.
Da Cruz is supplementing the matrix with what he calls a DOT—short for department of transportation—mix. The mix is made up of 40% perennial rye grass, 40% colonial bent grass, 10% creeping red fescue, and 10% white Dutch clover.
Why this particular mix? For one thing, the grasses Da Cruz chose have strong root systems that will provide stability to the steep 3:1 slopes on which they’ll grow. The mix also contains grasses that grow at different times of the year. For instance, the perennial rye grass will grow quickly and then be replaced by the slower-growing colonial bent grass. The creeping red fescue, which also grows quickly, features the strongest root system in the mix, stabilizing the soil and allowing the slower-growing grasses to sprout.
To further prevent erosion on these steep slopes, Da Cruz and his workers rely on the process known as “tracking,” a popular method in the northwest United States where heavy rains can wash away seeds in an instant. To track a hill, workers drive excavators with metal tracks up the slope, making a series of dimples in the earth. These dimples then help hold seeds in place, even if a heavy rain should wash over the hill.
When his company is done with the Issaquah Highlands project, Da Cruz will have overseen the vegetation of 700 acres. That figure is misleading, though; Northwest Erosion Control will have seeded some of these acres more than one time.
To Da Cruz, the natural products he is using on this job are far from innovative. He’s been using vegetation to stop erosion for years. Other contractors, too, are relying on the products, he says.
“There is more education available now than there had been in the past,” Da Cruz says. “There are classes offered here in Washington that teach about the different erosion control products available. They always talk about some of the more natural products. These products are so important in today’s world. People are always looking to use bonded fiber matrix and hydroseeding.”
Increasing Demand
The calls have come in more frequently. The e-mail messages have, too.
In fact, David Gilpin, president of Livermore, CA–based Pacific Coast Seed Inc., now receives e-mails and phone calls every day from contractors and developers. They’re all asking the same thing: What combination of seed should they use to best fight erosion?
“My job is to work with people to develop a program where we can help match the ability of the seeds and the plants that they are choosing to try to meet as many goals as they can with a minimum amount of risk,” Gilpin says. “Some plants develop quickly, some slowly. The more quickly they develop, the fewer long-term erosion control treatments the client needs to provide. The slower the plants develop, the more integrity the erosion control treatments need to provide before the plants can provide it.”
Gilpin and Pacific Coast Seed have worked in the erosion control field for years. The company collects and produces wild native California seeds and provides erosion control products such as mulches, bonded fiber matrix, compost, inoculants, binders, erosion control blankets, and fiber rolls.
Many clients are becoming more interested in using seed and vegetation to slow erosion on their projects. A good example is Squaw Valley USA, a well-known ski resort in Olympic Valley, CA. The resort hosted the 1960 Winter Olympics.
Pacific Coast Seed has worked with Squaw Valley for 15 years, helping resort officials modify their seeding program during this time. Pacific Coast provides seed mixes that resort officials use to repair areas of their ski range that have been damaged during the season. Other seed mixes are designed for ongoing maintenance at the resort.
Then there are the special projects. The resort has added new ski towers over the years. When it does, Pacific Coast provides seed mixes designed to quickly grow vegetation around these towers—mixes that prevent serious erosion from occurring.
“The resort has constantly, naturally changed its seeding programs during the last 15 years to meet its changing needs,” Gilpin says. “The resort has changed its seeding programs in response to changing environmental regulations that the ski industry has experienced. During the last 15 years, for example, the resort’s use of native plants has continued to accelerate. Its use of non-native species has gone down.”
Providing natural erosion control options to California clients can be a tricky science, Gilpin says. The state features several different environments and climates, including mountain areas, deserts, and coastal regions. Each of these areas requires different seed mixes to produce plants that thrive in their unique conditions.
The state has kept Pacific Coast Seed busy. The company, for instance, provided seed mixes and erosion control products to the developers of Quarry Village, a housing project in Hayward Hills, CA, currently being developed on 30 acres of abandoned quarry. The company has also tackled vegetation projects for traditional housing projects and provided seeding for mine operators.
And while seeding is a good solution for erosion problems, many clients turn to vegetation because it serves other functions, too.
“On most jobs, controlling erosion is the primary application. But our clients usually have other concerns, too,” Gilpin says. “They may be concerned about enhancing the environment for wildlife. They may be interested in aesthetic beautification. They may even need to preserve an Indian burial ground. When we delve into it, it’s usually about more than erosion control. Other times we have to consider our client’s plans for the land down the road. We try to take that into account as we do our planting mixes so that our clients will be on track to meet their goals next year.”
Gilpin says he’s not surprised at the continued popularity of his company’s seed mixes. Vegetation, he says, is almost always the most stable form of erosion control.
“The binders and straws that people can apply are all temporary erosion control measures,” Gilpin says. “The most effective permanent erosion control is the three-dimensional strength you get from plants, from their roots binding.”
A Necessary Evil?
Only the most naïve would view the increased demand for vegetative erosion control measures as simply good will on the part of contractors and developers. A possibly bigger reason for this boost of interest? Doug Graham, of Renton, WA–based Fiber Marketing International Inc., points to tougher federal and state regulations.
When the second phase of the National Pollutant Discharge Elimination System (NPDES) took effect in 2003—and placed federal erosion and stormwater regulations on smaller construction sites—many contractors had to scramble to enact erosion control measures that would allow them to avoid costly fines and shutdowns. One of the choices? Vegetation.
“Vegetation is an obvious choice for recovering the soil surface when it’s disturbed,” Graham says. “Usually, if seeds are selected carefully, it’s self-sustaining and self-maintaining, provided that there is adequate moisture for the seeds to get established.”
This self-sustaining aspect differs from other erosion control measures. Products such as silt fence and sediment control devices require ongoing maintenance.
“We’ve seen that more counties and city municipalities have been exposed to the new NPDES rules and to programs that encourage the planting of vegetation with some sort of mulch cover,” Graham says. “Generally speaking, the least expensive mulch cover is desired. People still don’t want to spend extra money on erosion control if they can help it. Contractors usually view erosion control as a necessary evil.”
Fiber Marketing International sells hydraulic mulch products for use in hydroseeding applications. Graham says hydroseeding is the most economical, and fastest, way to apply seeds to the soil, especially if contractors are dealing with slopes.
The popularity of hydroseeding is increasing, too, Graham says, as contractors attempt to build homes and commercial properties on more challenging sites.
“That’s where hydroseeding is particularly effective, as we see more construction up hillsides or in tight spaces that leave significant grade changes between two pads,” Graham says. “We get involved in sites that are either too steep, too rocky, or too small.”
In Graham’s market, this is common. His company primarily serves the western portion of the United States, where, he estimates, 80% to 90% of building sites are not flat. In the Midwest, of course, more land is flat. Hydroseeding in that part of the country is far less common. In flat areas of the country, contractors can simply drill-seed and then cover their work with vegetative mulch.
Contractors have to consider their environments when choosing not only the right mix of seeds but also the best way to apply these mixes. They also have to consider timing. Planting seeds at the wrong time won’t do anything to prevent erosion.
“There is a lot to consider,” Graham says. “Just look at seed selection. Much of the work around here is seeded with native or adapted species that are planted in the fall. They are dormant, meaning that the seeds have to be in the soil, wet, and frozen a number of times before they actually germinate. A lot of vegetation in late fall has to stay in place over the winter, on through the spring, and then germinate or emerge in late spring or summer.”
The Search for “Friendly” EC
Allmon of Critical Site Products doesn’t discount the effect of regulations and the threat of fines. But there is also a more altruistic reason why contractors and developers are choosing vegetation to help control erosion, she says: They’re searching for more environmentally friendly ways to stop soil from eroding.
Much of this demand, of course, stems from clients with a “green” bent. They want to support builders who recycle their waste materials and erect energy-efficient homes. They want these same builders to do their part to control site erosion. Much of the demand for environmentally friendly erosion solutions also comes from municipalities trying to find ways to stop flooding and stormwater problems.
“We want things that are more environmentally friendly,” Allmon explains. “Consumers might want to work with a home developer who does more green, friendly development. They might support a business that is known to do green things. People vote with their dollars.”
Then there are the stormwater issues municipalities are facing. When areas are built up with homes and retail facilities, the land absorbs far less rainwater. The water that isn’t absorbed then runs off into storm sewers and into streams. The water erodes streams and ponds before emptying into rivers.
“We lose unbelievable amounts of topsoil every year,” Allmon says. “People are starting to understand this. There are many more floods than when we were children. Municipalities are requiring that builders take measures to control rainwater and erosion on their sites. Vegetation is a good option.”
An example of this is Kensington Farms, a new housing development planned for Lee’s Summit, MO. The subdivision, being developed by Pulte Homes, will feature a series of large rain gardens designed to absorb stormwater before it runs off into nearby storm sewers. One of the rain gardens is scheduled to cover more than 5 acres. Pulte Homes is also encouraging homeowners to develop their own rain gardens or no-mow or low-mow yards to help absorb rainwater.
“You don’t see someone like Pulte Homes do that if they don’t know it’s going to help sell houses,” Allmon says.
Allmon considers the rain gardens as a nontraditional form of stormwater and erosion control that consumers are more likely to appreciate and accept.
“It’s not like you have a bioswale in your yard,” she says. “You have a beautiful garden. And it’s not just beautiful, it’s working. It’s a lot more subtle than a wetland or a mitigated area is.”
Allmon says she expects the demand for environmentally friendly erosion control initiatives to only increase as builders continue to develop large housing communities and retail centers.
“It’s not that we shouldn’t urbanize or build houses or roads or services,” Allmon says. “But there are going to be more people. There is going to be more demand for improved and expanded communities. People need to be responsible to handle the water they receive on their properties. People shouldn’t be just saying, ‘If I can get it off my property, there’s no problem.’”
Tackling the Busy Season
Rob McGann, estimator for San Marcos, CA–based Hydro-Plant Inc., is used to tackling big projects. He and his company are now in the middle of providing erosion control services for a six-year housing development in San Diego.
The project, Black Mountain Ranch, is a nearly 5,000-acre master-planned community. McGann and Hydro-Plant are currently vegetating close to 300 acres that will soon be home to schools, parks, and residences.
Hydro-Plant crews are seeding these acres with a mix of Plantago insularis and three-week fescue grass.
The decision to select this particular mix wasn’t one that McGann and his fellow staffers took lightly. Plantago is particularly useful because it grows so quickly. With the winter season approaching in San Diego, this is important.
Timing was another factor that McGann had to consider before selecting a seed mix. Construction crews working on the housing project must, according to local regulations, shut down their site before the winter months start. That means that Hydro-Plant crews needed to act quickly to reseed cleared earth. Their time frame for handling the project was extremely short.
To solve this challenge, Hydro-Plant sent four crews out at a time on reseeding work. Usually, the company would have sent out just two at one time.
McGann expects more demand for his company’s services in the coming years, as a greater number of contractors turn toward natural means to slow erosion on their work sites.
“We always advocate seed as a way to control erosion,” McGann says. “They especially want us to use seed here in San Diego. They truly do encourage it here. We are kind of the poster child here for vegetation.”