Road Ecology Center

Erosion control is an important issue that the Texas Department of Transportation (TxDOT) must address on every construction and maintenance project. As topsoil sources have become depleted over the years, it has been observed that the most basic part of revegetation, a 4-inch topsoil seedbed, is actually soil with little or no organic material necessary to sustain plant growth. This has led to severe erosion on many projects. The consequences for failing to effectively control erosion are very costly. In addition to potential fines by the Environmental Protection Agency (EPA), repeated efforts to revegetate erosion-prone areas also increases the cost of projects. Erosion is costly and time-consuming from every aspect. If erosion occurs while the project is still under contract, the contractor must reapply topsoil, seed, fertilizer, and mulch and/or erosion control blankets. If erosion occurs on existing sections of highway, maintenance personnel are left to deal with the resulting problems which include re-working the soil and re-seeding, none of which they have the time or money to complete adequately. TxDOT searched for an alternative method and quickly saw the benefits of utilizing compost as an erosion-control tool. The compost alternative, which is comparable in cost to the topsoil method, provides a more effective solution to the erosion problem by adding organic matter to poor soils as a soil amendment so that revegetation can occur. Erosion is avoided and TxDOT saves time and money that would have been expended for repeated topsoil applications where growth failed to occur. In addition, highway construction practices have been viewed as potential contributors of nonpoint source pollution that is caused primarily by sediment runoff from improperly maintained or vegetated construction sites. Previous studies have shown that compost, a recycled material, can alleviate this problem by providing a barrier between rainfall and surface soil to dissipate the impact of rainfall and reduce erosion.