THE VIRGINIAN-PILOT
Copyright (c) 1995, Landmark Communications, Inc.
DATE: Friday, July 21, 1995 TAG: 9507210008
SECTION: FRONT PAGE: A12 EDITION: FINAL
TYPE: Letter
LENGTH: Short : 32 lines
Thirty years ago, as a civil engineer, I tried five-cubic-yard sandbags covered with heavy plastic along the dune line in front of the Naval Facility at Buxton on Hatteras Island. The bottom bags were dug in 4 feet deep and those on top sloped back at a 45-degree angle up to the top of the dune.
I watched during the first storm to hit them. The waves would smack them hard and ride on up over them. The most damage occurred from undermining as each wave receded, taking sand out with it. Pretty soon the bottom row of bags began collapsing into the void, and those bags above tumbled down, often askew. By the next morning, the bags were all over the beach.
The bags did help for that one storm, but that was all.
The bags shown in your MetroNews section on July 10 appear to be much longer than my bags, and I notice that the ones in front of Dam Neck are of a heavy-gauge canvas so that perhaps they will last longer. Considering the magnitude of the mass, velocity and frequency of the waves in a storm, not much can stand up against the impact, and especially the undermining.
I hope the information will help current engineers and homeowners.
W. W. PATTERSON
Suffolk, July 10, 1995 by CNB