Town of Hilton Head Island
Islandwide Drainage Study 1995

The storm drainage design requirement for the 1950-1980's of the Island's development was a 10 year frequency storm or less than 3 inches of rainfall. In attempting to simulate a 25 year, 24 hour storm (8 inches of rainfall) with the existing drainage system, bottlenecks are identified throughout the Island. To retrofit the existing drainage systems to accommodate the 25 year storm requires minor improvements for the plantations and major improvements for the non-plantation areas.

In 1995, the Town of Hilton Head Island completed an Island-wide Drainage Study which contains the following:

1. Town of Hilton Head Island storm drainage facility composite map and drainage inventory. The composite map and inventory give detailed information on the Town's major drainage flow patterns and should be an invaluable tool for all future Town development and planning.
2. Listing of storm drainage bottlenecks which occur in the major drainage system during a 25 year, 24 hour storm (8 inches of rainfall in 24 hours).
3. Preliminary drainage improvement plans to alleviate the identified drainage bottlenecks.
4. Engineer's Opinion of Cost for each of the Preliminary Drainage Improvement Plans.

The Drainage Study gives 17 drainage projects totaling over $17.5 million that should be undertaken to improve the drainage on the Island. These projects have been incorporated into the Town's 10 Year Capital Improvement Program.