Britt Faucette
Filtrexx International
Control of runoff on construction and agricultural sites is critical to minimize erosion and prevent sediment and other pollutants from entering surface waters. Although construction sites are considered point sources of pollution with erosion rates up to 25% greater than agricultural lands, research using compost products for runoff control on construction sites can be applied to farmland. Current research indicates that specific compost applications can be more effective than standard runoff control practices but require the compost meet strict specifications for quality and installation.
Controlling erosion at construction sites requires designing a system that optimizes plant growth and water absorption. Erosion Control Blankets (ECB), a thick layer of compost blown onto disturbed soil, is effective in dissipating the energy from the impact of raindrops, increasing the water holding capacity and evaporation potential of the surface, slowing and dispersing the energy from sheet flow and optimizing vegetation growth. Research comparing compost ECBs with hydromulch/silt fence treatments indicated that the ECB reduced the total runoff volume and peak runoff rate and increased infiltration volume both on Day 1 and 3 months later for a simulated storm with rainfall of 4 inches/hour. In addition, the vegetative cover 3 months after installation was 3 times greater for the ECB and after 12 months had 1/3 fewer weeds.
Controlling sediment and nutrient runoff requires interrupting the flow to allow trapping of sediments, absorption of nutrients and degradation of organic compounds. Silt Soxx (SS), filled with a coarse compost, can be used to create a sediment and soluble pollution detention device or filter. In addition to restricting water flow, which allows the sediments to settle, the SS is a more effective filter than a silt fence as it is less likely to become clogged, resulting in increased solids and nutrient removal over the long term and requiring less maintenance.
To view the presentation online, go to http://liveclick.ag.ohio-state.edu/cgi-bin/ImageFolio31/imagefolio.cgi, click on OCAMM then click on the television icon on the right. You will need RealPlayer to watch the broadcast.
For a more detailed review of Dr. Faucette’s research, his PhD dissertation is available online: http://www.filtrexx.com/downloads/britt_faucette_phd.pdf
Discussion:
Rick Wilson (OEPA) asked if, during certification of the compost, clean water is run through the compost as a control to determine runoff nutrients before contaminated water is used. Faucette replied that clean water is not used, but if there is a spike in nutrients, the compost will not be certified. Electrical conductivity is measured to detect the presence of salts that would indicate nutrients.
Fred Michel (OSU) referred to a slide that indicated phosphorus (P) in the runoff. Where is the P coming from? Faucette noted that there are some nutrients in the compost and hydroseed as these are needed to establish vegetation.
Wilson mentioned that in western Ohio, an Ohio Department of Transportation group uses livestock manure from the fairgrounds along ditches to stabilize the soil and establish vegetation. Faucette replied that it is not a standard practice.
Wilson asked if compost comes from large operations and how much, if any, is manure based. Faucette noted that it is all yard/green waste compost and reiterated that the specifications are important. Maturity is important. Also, the compost needs to absorb water to reduce the total load. Wilson commented that reducing soil movement will reduce P levels in surface water.
John Smith (OSU) asked about the process of applying the mulch blanket. Britt clarified that the mulch itself is the blanket. It is pneumatically blown onto the soil creating a mat. For steep slopes, netting above or below the mulch increases stability.
Smith asked if the seed is mixed into the mulch. Yes, it is injected into the system from a hopper.
Smith asked how to receive a copy of the Filtrexx Best Management Practices Design Manual. It is available on the website (http://www.filtrexx.com/).
Dave Ritter asked how a filter berm or SS is inspected to determine whether or not it is functioning. Faucette replied that the level of the water being held is the main indicator. It is especially important for a berm which can overtop or blowout when water levels are too high.
Ritter questioned the life expectancy of the Silt Soxx. Faucette replied that UV tests have been run on the different materials used. The actual life is a factor of material, sun exposure and rainfall. Some are intended to be biodegradable and breakdown within 6 months. Those made from HDPE last 2-3 years while those made from polypropylene are still intact.
Notes by Mary Wicks
The OCAMM (Ohio Composting and Manure Management) Program is funded by OARDC/OSU.