Eroding Adirondack Slopes

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."

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