The Environmental Protection Agency (EPA) has required the South Carolina Department of Transportation (SCDOT) to obtain National Pollutant Discharge Elimination System permits for storm water discharges from construction sites. EPA has assigned regulatory authority for issuing these permits to the South Carolina Department of Health and Environmental Control (DHEC). Additional regulatory requirements have been implemented by DHEC's delegated authorities. These additional requirements further define the EPA regulatory requirements and mainly comprise limits on the effluent from construction-site runoff. The effluent limits for construction-site runoff have been set to achieve an equivalent removal efficiency of 80% for suspended solids or a peak settleable solids concentration of 0.5 ml/L. Only one of these effluent limitations must be met to satisfy the permit requirements. DHEC's delegated authorities will issue permits on the basis of standard engineering calculations that show that the proposed sediment basins will meet the required effluent limitations. A computer program named SEDIMOT is recommended by DHEC's delegated authorities to establish the sediment basin sizes. SEDIMOT was used to model standardized sediment basins that will be used by SCDOT throughout South Carolina. The state was divided into two hydrologic regions (Piedmont and Coastal Plain), and two statewide soil categories were determined for the computer simulations. A range of sediment basin sizes was determined with SEDIMOT that meets effluent limitations for each region and soil category in the state. This information was summarized in charts for SCDOT to use in the design of sediment basins. The charts provide the required sediment basin size depending on the drainage area for each region and soil category in the state. SCDOT intends to use the charts to determine the sediment basin sizes that will be included in permit applications to DHEC's delegated authorities.