seismic reflection equipment and the vibracorer to successfully identify sand 

 resources; the surveys have continued to the present time under an expanded 

 program, the Inner Continental Shelf Sediment and Structure (ICONS) program. 

 ICONS survey results from many areas along the U.S. seacoasts and Lakes Michigan 

 and Erie are available in numerous CERC publications. Prins (1980)^ provides a 

 brief discussion on methods and requirements for conducting such surveys. 



The original Alpine Vibracore has been modified to obtain 20-foot-long 

 (6 meters) cores in sand; subsequently, 40-foot-long (12 meters) continuous 

 cores have been obtained. This coring apparatus is now available from several 

 private firms and research groups in the United States and other countries, and 

 is the most efficient method for obtaining long cores in unconsolidated sedi- 

 ments. A 20-foot vibracorer is available from the U.S. Army Engineer District, 

 Mobile, on a cost reimbursable basis, for use by the Corps. 



1. Vibracore Components . 



The primary components of the vibratory corer are shown in Figures 1 and 2 

 and are listed in the Table. The central mast consists of an aluminum H-beam 

 (several feet longer than the core barrel used) , which acts as a guide and 

 support for the vibrator head and core barrel during the coring process. The 

 H-beam is supported in a vertical position on the seabed by four legs. One of 

 the legs is hinged so that the coring frame can be placed on its side on the 

 deck of the platform for ease of loading the core barrel and removing the core 

 liner after the coring operation. When the core apparatus is hoisted off the 

 deck for deployment at a core site, the articulated leg locks into proper posi- 

 tion for placement in the bottom. The actual sampler consists of a pneumatic 

 impacting piston vibrator head fixed on top of a standard 4-lnch steel pipe 

 which is loaded with a clear plastic liner to contain the sediment sample. To 

 aid in core penetration and recovery of the sediment after pullout, a steel 

 cutterhead Is threaded to the end, and a metal core catcher with thin curved 

 "fingers" is attached to reduce loss of muddy sediments. 



After the coring frame is resting on the bottom, the vibrator head and 

 barrel are driven through a hole in the baseplate. When coring is complete 

 the barrel is pulled back into the frame along the H-beam before lifting the 

 frame to allow for straight pullouts which minimize the chance of bending the 

 core barrels. 



The pneumatic vibrator is powered by a compressor 250 cubic feet (7.08 

 cubic meters) per minute at 120 pounds per square inch onboard the coring 

 platform; three intake and exhaust hoses provide the connection. 



A complete description of the vibratory cores is provided by Tirey (1972)^, 



^PRINS, D.A. , "Data Collection Methods for Sand Inventory-Type Surveys," 

 CETA 80-4, U.S. Army, Corps of Engineers, Coastal Engineering Research Center, 

 Fort Belvoir, Va., Mar. 1980. 



^TIREY, G.B., op. cit., p. 7. 



