Scope of Services

SEDIMENT SAMPLING

Gravity has extensive sediment sampling experience, we understand both the technology and the significance of data quality objectives. We can help you choose the right tools for the job. With our custom vibracorer and power grab samplers we collect superior and more reliable data providing consistent sampling recovery, deeper penetration, and the ability to sample hard substrates. The use of these instruments allows us to collect less disturbed samples in environments and substrates that other instruments cannot.

• Subsurface sediment coring –vibracoring technology, direct push and Auger Drilling, sedflume sampling
• Surface grab sampling – Custom power grab units for collecting surface sediments for benthic
• Beach and near-shore sampling – portable coring system, eckman and ponar grabs, amphibious vehicle and shallow water support vessels
• Sediment load studies – source and transport evaluations. Gravity owns multiple LISST in-situ particle analyzers and an array of sediment traps and equipment for loading studies

BIOLOGICAL AND FISHERIES STUDIES

• Fisheries studies – counts and tissue sampling using electrofishing equipment, habitat enhancement
• Benthic surveys – invertebrate sampling, sieve analysis, taxonomy sampling, shellfish surveys
• Toxicity testing – in situ toxicity studies, field scalable research studies

OCEANOGRAPHY

• Depth profiling & water sampling systems – sensor integration
• Real-time monitoring buoys for turbidity & water quality compliance monitoring
• Current profiling arrangements for nearshore and deep ocean measurements
• Robotic Underwater Vehicle operations

GEOTECHNICAL

Gravity provides marine geotechnical site investigations for determining sediment geology to give data for marine hydrodynamic and morphodynamic studies. We employ a broad range of drilling, sediment sampling, and in situ equipment to provide data for engineering and design. This data can then be used to determine the type and use of preventative measures to mitigate possible settlement, soil erosion, or cross-contamination.

• Subsurface sediment coring using vibracore, direct push and auger systems
• Mud depth surveys for channel dredging using in-situ sensors including Gravity’s Custom Graviprobe system
• Sediment CPT and shear strength measurements

HYDROGRAPHIC

Through all phases of waterfront and underwater projects, hydrographic surveys provide critical information about the depth and character of the bottom. Gravity provides hydrographic surveys around the world to clients in all phases of projects, often working in difficult-to-reach areas.  Hydrographic surveying capabilities include high-resolution multibeam sonar, single-beam sonar, and airborne hydrographic LiDAR surveying services.

Hydrographic surveying capabilities including:

• High-resolution multibeam sonar for wide swath bottom mapping
• Interferometric sonar for 3d imaging of seafloor
• Single-beam sonar for shallow water and cost-effective surveys
• Airborne hydrographic LiDAR surveying services

MARINE GEOPHYSICAL

Marine geophysical investigations document underwater geology, providing a direct cost benefit to design and construction projects, dredge planning, and search and recovery missions.

• Side-scan sonar surveys map underwater surfaces, providing an acoustically generated image of the seafloor or riverbed features.
• Subbottom profiling surveys map underwater subsurface geology using seismic reflection or refraction technology.
• Magnetometer surveys measure ambient magnetic field and can locate concentrated masses of ferrous material.
• UXO – unexploded ordinance surveys for marine waterways and construction assessments.

WATER SAMPLING

Gravity Consulting has extensive experience in the support and implementation of water quality
monitoring programs. From trace organic high volume sampling to sediment transport studies, Gravity has the instruments, knowledge and expertise to implement a successful study.

• Trace contaminant sampling – proprietary High Volume System designed to separate dissolved and solid-phase contamination with the ability to achieve ultra-trace level detection limits
• Oil spill response – water column studies and in-situ equipment for the rapid evaluation of oil concentrations. Gravity has specialized experience and equipment for supporting oil spill studies and modeling efforts
• Water monitoring – NPDES permit sampling, in-water construction oversite, remote telemetry systems for 24-hour monitoring operations

ENVIRONMENTAL TOXICOLOGY AND RISK ASSESSMENT SUPPORT

Gravity staff have extensive experience supporting data collection for risk assessment and toxicology projects working in both the upland and marine environments. Gravity provides the technology, equipment and in-depth understanding of the risk assessment process to collect the data needed to best characterize your sites.

• Contaminant fate and transport studies
• Bioaccumulation and bioavailability modeling
• Toxicity identification and reduction evaluations (TIEs/TREs)
• Screening level and baseline risk evaluations
• Human Health and Ecological probabilistic assessments