Innovative Product Solves Challenge of Growing Grass on Difficult Slopes
As seen in 'Soil Erosion and Hydroseeding Magazine'
By Colleen Lyman
Transforming Tangipahoa Parish's landfill's 15 sloped acres of eroding soil into green vegetation was no easy feat. Erosion had caused the landfill in Amite, Louisiana, to provide continuous maintenance costing unnecessary dollars. In addition, the Louisiana Department of Environmental Quality requires that grass cover the landfill's slopes to prevent soil erosion.
Fortunately, Landfill Solutions, LLC, Baton Rouge, Louisiana, a problem-solver for landfill concerns, was up to the challenge. After a failed first erosion-control attempt, the company devised an innovative solution that had the landfill looking more like a lush putting green than a garbage receptacle.
The Tangipahoa landfill, which receives 400 tons of municipal solid waste daily, had several characteristics that made growing grass on its slopes difficult. First, the texture of the soil is sandy clay - causing pH problems and poor soil quality. Second, the slopes are particularly steep - more than 90 feet of soil that was angled 3:1 straight down. As a result, soil washed down the sides when it rained.
Initially, not fully appreciating the slopes' degree of difficulty, Landfill Solutions positioned berms to control erosion and planted grass to cover the hill's surface area. Unfortunately, storms quickly washed away soil, grass seed, hydromulch and fertilizer.
"Our first failure taught us that we needed to manage the excess water that was causing the erosion in the first place," said Don Breaux, owner of Landfill Solutions. "In effect, we needed to tell the water where to go. Managing the stormwater was critical to ensuring long-lasting vegetation."
Utilizing his chemical engineering knowledge and years of experience in promoting alternative landfill cover, Breaux proposed an ingenious plan. To capture the rain water on the top of the landfill, he recommended erecting a system of large 'berms' centered on the top of the hill. Next, seven strategically placed 'let-downs' (drainage chutes) were extended from the berms to the bottom of the hill. The let-downs were lined with non-biodegrading plastic mats, and stapled and nailed down with spikes every 3 feet to prevent them from washing away. At the bottom of the slope, large drainage ditches were formed to contain the water.
The system effectively diverted stormwater from the soil at the top and directed it into the drainage ditches at the bottom. "By creating specific avenues for waterflow, we prevented water from washing away new seed growth and also ensured that the runoff water was uncontaminated by dirt and debris," said Breaux.
In addition, Landfill Solutions realized that it would also have to better shield the seeds during the germination process. To protect the seeds and hold them in place, Breaux utilized an innovative product, ENVIRO-SHIELD® bonded fiber matrix from USG's Specialty Products Division. The unique and environmentally safe product not only helps stabilize the soil after seeding, but its calcium sulfate nutrients also enhance the soil’s nutrition.
"We applied the product to the landfill slopes to help ensure that the seeds wouldn’t wash away and that they would grow evenly,” said Breaux. "After seeding, applicators spread approximately 3,400 pounds of ENVIRO-SHIELD matrix over the entire area.
"The application process was relatively easy. First, operators mixed 1,000 gallons of water with approximately 14 50-pound bags of ENVIRO-SHIELD matrix in a hydroseeder tank. They then applied the thick green oatmeal-like slurry by spraying a thin layer (about ¼-inch thick) evenly over the slopes.
The product's matrix incorporates gypsum, a strong soil amendment, into the mix of fibers, along with special water holding ingredients. When applied in this liquid form, the ENVIRO-SHIELD matrix forms a sprayed-in-place breathable blanket to hold the seeds in place. Although the seeds cannot move, water can permeate the shield to germinate them.
Breaux also chose a hardier strain of grass than was planted the first time. Because this project took place in the winter, Breaux chose a rye variety that germinates within four weeks - much faster than other varieties, such as Bermuda, which can take as long as 10 weeks.
In as few as four weeks, the seeds were already growing strong and after 10 weeks, the grass blanketed the hill with a thick, uniform cover. Everyone involved was pleased with the results. "We utilized creative ingenuity and leading-edge products to ultimately design an effective plan,” said Breaux. "The landfill is covered with vegetation that not only looks lush, but prevents erosion as well.”
