Home » Services » Geotechnical Sampling » Grab Sampling

Grab Samples

Sediment grab sampling is a method used to obtain samples for characterization of surficial material.  Grab sampling is useful for acquisition of samples used for grain size analysis, benthic habitat delineation, or ground truthing of sonar records.  OSI maintains a wide variety of industry-standard grab samplers including Van Veen, Ponar, Shipek, Ekman Box, and Smith McIntyre samplers.  This versatile inventory of sampling devices provides cross-sectional sampling areas from 6” x 6” up to 14 1/8” x 11”.

Read More

OSI also operates custom designed and fabricated pneumatically actuated grab samplers (PAGS).  The system is equipped with an underwater camera which enables the operator to view the sample site prior to landing the sampler on the bottom.  This enables the operator to “dodge” obstructions and/or debris that would be likely to prevent sample acquisition and/or obstruct the closure of the sampler jaws.  Likewise, the camera may provide an explanation for poor recovery if this is in fact the end result.  Once the sampler is landed and penetrates into the sediments, the jaws are closed by the operator from the surface using a pneumatic actuator.  Unlike a Van Veen sampler, the PAGS gives the operator control over sample acquisition and increases the likelihood of acquiring an acceptable sample with the fewest attempts.  The sampler is configured with doors to minimize washout and disturbance of the sediment surface.  Penetration is adjustable to a maximum of 12 inches with realistic sample retention at penetration depths of 10 inches.  As with any grab sampler deployable from an economical sampling vessel, in coarse material, penetration may be limited.  The PAGS may be fitted with a low energy, high-frequency vibrator that may be engaged, as needed, to assist penetration in certain substrates such as gravel or small cobbles.      

Representative Projects

Marsh Restoration Fig. 3

Marsh Restoration: Whiskey Island, Louisiana

Integrated hydrographic/geophysical surveys and a vibratory coring program were completed in the Gulf of Mexico in the waters offshore of Whiskey Island, Louisiana for the LDNR and The United States Environmental Protection Agency. OSI completed these investigations under subcontract to ...
Ocean Outfall Fig. 2

Ocean Outfall Monitoring: Ponce, Puerto Rico

Ocean Surveys provided water quality monitoring services at an ocean outfall monitoring site to support a 301(h) Waiver and Mixing Zone Validation Study offshore Ponce, Puerto Rico. OSI field teams conducted 11 quarterly surveys at the Ponce effluent outfall.  Services ...
Power Generation and Distribution: Puerto Cortes, Honduras

Power Generation and Distribution: Puerto Cortes, Honduras

Ocean Surveys performed a multi-disciplined marine investigation including hydrographic, geophysical, oceanographic, meteorological and biological studies in the waters off Puerto Cortes in the Gulf of Honduras. This investigation was conducted to collect scientific data in support of the design of ...