Cost Performance Index of Temporary Erosion Control Products (0-5309-1)

The objective of this research project was to develop a cost-performance index (CPI) for products in the Texas Department of Transportation's (TxDOT's) Approved Products List (APL). TxDOT's APL was created from performance testing conducted in the Hydraulics, Sedimentation, and Erosion Control Laboratory (HSECL) of the Texas Transportation Institute (TTI). The performance testing includes sediment loss and vegetation growth. Both slope protection and channel protection products are evaluated. The intention of developing the CPI was to further include cost data in the APL so that users of the APL can justify the use of a product based on the combined cost and performance information. Data used for the CPI development include surveyed cost from manufacturers, material composition and sediment loss performance data from TTI performance testing. The conceptual model of the CPI can be described as "the benefit of potential soil protection per unit cost of both product and potential topsoil replacement expense." The benefit of potential soil protection is a hypothetical cost savings from slope or channel failure over the entire product lifespan. The potential topsoil replacement expense reflects the fact that soil loss will occur no matter how well the surface is protected. When soil is lost, there is a potential of topsoil replacement, which in turn costs money. With this concept, a typical topsoil price of $25 per cubic yard was used. The result of the project includes a series of tables listing products with high/medium CPI. Five project durations were used: temp (0-3 months), short (3- 12 months), mid (12-24 months), long (24-36 months), and permanent (36-54 months). For slope protection products, two slopes and two soil types were included: 2:1 clay, 3:1 clay, 2:1 sand and 3:1 sand. For channel protection products, six shear stresses were used to separate different products: 0-2, 0-4, 0-6, 0-8, 0-10 and 0-12 lb/ft2. The improved APL will enable erosion control designers and specifiers to select products best suited for different project durations with great cost-savings potential.