Assessing Beach Fill Compatibility through Project Performance Evaluation

Part of the design processes in beach nourishment projects is to determine the suitability of the borrow material for placement on the native beach. Ideally the sediment would be of similar grain size distribution, shape and color. Often the borrow source is a different environment and therefore a different size distribution and predicting the amount of borrow that will remain on the profile once it is placed is problematic. Case studies on past projects indicate that fill compatibility is complex and not well predicted by using the standard suitability methods. Use of the entire grain size distribution is needed to better predict performance. Borrow material similar to the native sediment will return to a native distribution within one year, while finer or coarser distributions take longer to equilibrate. Coarser borrow material seems to provide a more stable fill. Fill volume is also important along with grain size in project success.