Features Available Online

Sumter County Landfill: Growing Vegetation on Inhospitable Soil

A combination of Pennington Seed and Profile Products soil amendments overcame harsh growing conditions.

Landfills aren’t known as being particularly hospitable places. True to character, the soil capping of a cell in the Sumter County, South Carolina landfill, was pretty inhospitable to vegetation. The only way it was going to sustain plant life was to have life pumped into it. That could have been cost prohibitive, were it not for some creative solutions.

The Sumter County Landfill is located in central South Carolina. A 20-acre cell of the landfill was reaching its capacity, prompting officials to close it. Following fairly typical procedures, a six-inch layer of fill dirt was trucked onto the site and compacted over the trash layer. Officials applied an additional six-inch layer of topsoil over the packed layer and tracked to final grade. Then they collected and tested soil samples.

The engineering firm of Withers & Ravenel of Raleigh, North Carolina, worked with county officials to direct the efforts. Their goal was to not only establish vegetation as quickly as possible to stabilize the soil; they also wanted to ensure that the vegetation would be sustainable. According to Chad Tidd, Carolina Division sales manager for Pennington Seed and a consultant on the project, the second half of that order is traditionally the most difficult to fill.

“You see way too many sites where sustainability has not been considered,” Tidd said. “Vegetation gets established, but six months later it’s all gone, there’s nothing left. We were pleased that Withers & Ravenel took a long-range view for this project.”

Meeting that objective, however, took some education and innovation. Soil tests from the landfill cap conducted through the Clemson University Cooperative Extension, which does soil testing for Sumter County, determined the soil pH was around 4.5, with organic content only between 1-2 percent. The engineers called for the soil’s organic content to be at least 4 percent, and the soil pH between 6.0-6.5.

“Conventional thinking was to bring in massive amounts of peat or wood by-products to incorporate into the soil,” said Tidd. “The cost of that was going to be very, very substantial, so we offered an alternative solution.”

“Conventional thinking was to bring in massive amounts of peat or wood by-products to incorporate into the soil,” said Tidd. “The cost of that was going to be very, very substantial, so we offered an alternative solution.”

Working with Glen Ballinger, CPESC of Profile Products, Michael Gantt of Pennington Seed offered a proposal to Withers & Ravenel that included innovative new products.

NeutraLime was recommended at 160 pounds per acre to bring the soil pH closer to the 6.0-6.5 range and improve nutrient availability.

Five gallons per acre of JumpStart was needed to improve soil moisture infiltration and retention, and to provide a hormonal plant response for maximum root development and stress tolerance.

The 800 gallon Bowie hydromulcher applying product.

BioPrime was recommended at 160 pounds per acre to provide a slow release source for nitrogen (for nine to 17 months), ensuring plant health and optimizing delivery of macro and micronutrients to plants.

A specially formulated Slopemaster mixture of Pennington’s perennials, annuals and Durana White Clover was specified at 100 pounds per acre. The seed was coated with Germ Max Seed treatment to enhance germination and plant growth, and MYCO Advantage™ Endomycorrhizae, which enhances root mass, root growth and overall nutrient uptake by the plants.

The mix also included 100 pounds per acre of a water soluble fertilizer.

Gantt presented Withers & Ravenel background on the products and the research behind them. The engineers agreed that the package of products would be “equivalent to” the four percent organic content originally specified in the contract.

The soil treatments and seed were mixed with hydraulic mulch which was applied by an 800 gallon Bowie hydromulcher at 1,500 pounds per acre. The mulch holds 13 times its weight in water, for temporary erosion and sediment control and to keep seeds moist during germination. Work began the week of June 16, 2008, entering the hottest time of the year.

“This was an ideal mix of products for the site,” said Gantt, who was on site the day of the application to make sure it was done to specifications. “Within three to four days after seeding, we were already getting germination from some of the temporary vegetative material.”

Sustainable vegetation was a primary goal of the project.

The Result
The final Sumter County Landfill site inspection occurred in mid-July 2008. After four to five weeks of growth, permanent vegetation was growing throughout the 20-acre tract.

“We worked hard all the way through the process to change the site specification from ‘trucking in organics,’ which would have been very expensive, to putting everything in a tank and spraying it on the site in one easy process,” Tidd said. It took weeks of planning and effort to successfully grow the vegetation on the 20-acre tract.

“We were extremely pleased with the results,” said Gantt. “More importantly, the county, engineers and contractor were all extremely pleased with the results. They had no problem signing off on the project finalization.”

With a combination of products leading to a permanent stand of vegetation, the soil on Sumter County Landfill will stay in place and prevent erosion in the long term. L&W

For more information contact Dave Wegener, Swanson Russell, 1222 P Street, Lincoln, NE 68508 (402)437-6400, Fax (402)437-6401, davew@swansonrussell.com.