Vibracoring

KEI has designed and constructed custom vibracore sampling equipment that is routinely used to collect long-core sediment samples in deep and shallow water, in varying lithology, and under a variety of adverse conditions. The sampling platforms used to support this work include shallow-draft barges, open-water research vessels, whalers and other skiffs, and customized trucks for use in terrestrial and wetland areas.

Preparing a vibracore on the D.W. Hood for A-frame deployment in Southern California.
Sediment vibracoring using a custom-built quadrapod barge and whaler.

Vibracore sampling is a common technique used to collect continuous soil and sediment cores of up to 40 feet in length in unconsolidated soils and marine sediments. The vibracore is an excellent tool for obtaining geotechnical as well as environmental samples. KEI’s experienced personnel have used these vibracore systems for a wide variety of government and private sector clients in Alaska and Hawaii, along the Southern and Northern California Coastlines, in the San Francisco Bay Area, in the Sacramento and San Joaquin River Deltas, and in many lakes and rivers throughout California, along with locations in Texas, Ohio, Minnesota, and Louisiana.

Moon pool vibracore deployment with a winch on a custom-built quadrapod barge in Nome Harbor, Alaska.
Vibracoring with a stability cage in Morro Bay, California.
Open ocean vibracore with cage preparing for deployment

KEI’s proprietary vibracore systems consist of two counter-rotating three-phase, 220 volt electric motors sealed in a watertight aluminum housing. The motors are powered with a portable generator and controlled with a variable speed regulator that allows for frequencies between 20 and 60 Hz. A 4-inch diameter aluminum tube of the desired length is attached to the motor housing using a unique clamping system. The top of the tube is outfitted with a special check valve or a piston that facilitates core recovery and greatly improves retention of the core in certain types of sediments. A new food-grade polyethylene liner is inserted into the aluminum core tubing to form a clean barrier between the equipment itself and the collected sample material. Attached to the bottom of the tube is a stainless-steel core cutter and finger trap. The vibracore system can be attached to a stand, cage, or float package to keep the system upright in waters subject to wave action or strong currents. The systems have been successfully used on land in moist soils and in water depths of up to 1,500 feet.

Intertidal beach vibracoring from a monster truck fitted with truck tracks during low tide in Southern California.
Discrete vibracore sediment samples that are ready for processing.
Underwater photograph depicting vibracore penetrating the bottom sediment during a collection effort.