Protecting a site from erosion and restoring the area is always a concern among developers and project managers with most construction projects. This challenge can be amplified by slope, soil and extreme weather conditions, including storms and harsh temperatures. One project headed by Equitable Gas Co. (EQT), headquartered in Pittsburgh, faced what would turn out to be a record winter for snow and ice, creating an even higher potential risk of erosion than normal.
Even though the project was completed in early fall, project managers were aiming to protect the post-construction site from erosion and restore vegetation before winter temperatures dropped. The team worried that the arrival of winter would prevent seed from germinating and subject the site to winter rain and snow melt, any one of which would have delayed completion until the spring.
Finding the Right Product
In early fall 2013, EQT (now known as Peoples Natural Gas) completed a 10-mile pipeline project in the hills of Allegheny County, Pa., and needed to stabilize the site relatively quickly post-construction, when all soil-disturbing activities at the site had been completed and the site was ready for final stabilization.
Project managers working on the EQT pipeline project sought a product that would protect the area from erosion and return the vegetation removed during the construction phase of the project. The challenge they faced was finding a product that could either: A.) prevent erosion and quickly re-establish growth, or B.) protect the site throughout a harsh winter if growing conditions got too cold in the fall to establish sufficient growth.
After careful research, the production company chose EarthGuard Fiber Matrix (FM), a cost-effective alternative to rolled erosion control matting or blankets and other spray-on products.
EarthGuard is a soil-stabilizing emulsion, specifically formulated to work on the ionic level with soil chemistry to reduce erosion and sediment run-off. It is non-toxic, 100 percent biodegradable and conforms to the Pennsylvania Department of Environmental Protection Final 2010 Erosion and Sediment Pollution Control Program Manual. EarthGuard Fiber Matrix, a product developed by Terra Novo Inc., is a one-step application product that combines the proven erosion-control chemistry of EarthGuard with wood/cellulose fiber. It is applied as an aqueous slurry, either by itself or in combination with seed, using a hydro-seeder.
EarthGuard is chemically engineered to be effective at low rates while absorbing the impact of raindrops and providing immediate dust control, erosion control and soil stabilization until permanent vegetation is established or construction has resumed.
Preventing Erosion, Promoting Vegetation
Best defined as a stabilized fiber matrix, EarthGuard works in four different manners:
1. Throughout its service life, the product works directly on and continually with soil to prevent the degradation of existing soil structure caused by erosive forces.
2. EarthGuard’s long-chained negatively charged particles create a liquid net over the top of soil preventing the soil movement of small particles.
3. The product flocculates any sediment that might get dislodged during a rain event to reduce turbidity.
4. Fiber used in combination with EarthGuard prevents splash erosion.
As a result, EarthGuard promotes germination by stabilizing soil, amendments and seed while maintaining soil pore space which helps to preserve soil infiltration capacity and the ability of microbes to breath.
These unique attributes are unlike other products, such as bonded fiber matrix (BFM) or fiber reinforced matrix (FRM), which simply dry and harden to blanket a soil layer underneath, often creating a layer so hard and thick that it prevents seed germination and growth.
To be effective, BFMs and FRMs require a 3,500-lb/acre application rate on slopes 2:1 or greater. However, at its heaviest recommended application rate, EarthGuard requires at least 500 lbs fewer of fiber per acre. This results in less water required and a reduction in material and application costs.
In the past, on a typical pipeline project, EQT used erosion control matting, but using a stabilized fiber matrix offered significant cost savings. Less personnel were required to restore the site, the project was completed quicker and the overall applied cost was significantly less.
On Sept. 18, 2013, Penn Line Service of Scottdale, Pa., sprayed EarthGuard at a rate of 9 gallons and 2,500 lbs/acre of 70/30 wood/paper fiber across a 10-mile stretch. Other erosion-control products would have required two or three separate multi-directional applications to ensure full coverage. With EarthGuard’s quick, reduced-material application process, coverage of the site was completed in just one application.
By Oct. 15, 2013, full vegetation had been established while withstanding several heavy rain events, all of which pleased inspectors and the site’s project managers, Bruce Allen Inc.
For the EQT pipeline project, EarthGuard Fiber Matrix proved to be the best-suited erosion control and reclamation product to restore the site. Erosion was eliminated in the pipeline’s path, while vegetation was restored to its natural state well before the winter.
Scott Harrison is president and founder of Bakersfield, Calif.-based Terra Novo Inc., which manufactures erosion- and sediment-control products for the construction industry.