Since 1995, Sequoia Scientific, Inc. has been the global leader in technologies for submersible and field measurements of particles and particle size distributions. This article shows a few examples where our instruments have been used for various dredging and sediment monitoring applications.
USACE takes delivery of eight Sequoia LISST-200X instruments for sensitive habitat working unit
In 2019 and 2020, Sequoia delivered a total of eight LISST-200X submersible particle size analyzer systems to the United States Army Corps of Engineers (USACE) Engineer Research and Development Center (ERDC) in Vicksburg, Mississippi. Each system is comprised of Sequoia’s flagship LISST-200X laser diffraction particle size analysis instrument and accessories designed for both lab and in-field applications of the instrument.
The USACE will initially use the systems within their sensitive habitats working unit, focused on understanding dredge and placement activity impacts on corals and submerged aquatic vegetation. The instruments are planned to be deployed within the Honolulu Harbor, Hawaii and eventually in the State of Florida and other East Coast sites.
USGS Takes Delivery Of LISST-200X to Collect Klamath River Data
The United States Geological Survey (USGS) California Water Science Center took delivery in 2020 of a LISST-200X particle size analyzer at their Sacramento facility. The instrument will be used initially for establishing baseline analysis data for suspended sediment concentration and particle size distribution within the Klamath River.
European customer takes delivery of LISST-ABS and LISST-200X based sediment dredging measurement system
Sequoia, in collaboration with local WA-based Ocean Instruments has delivered a Fast Oceanographic Automated Measurement (FOAM) system for dredge monitoring to a European customer.
The FOAM system is composed of a pump and winch with a fluid rotary joint, 100 m hybrid cable with hose and conductors, a tow sled with an RBR CTD and a Sequoia LISST-ABS, and a topside mounted Sequoia LISST-200X running in flow-through mode.
The sled is towed through the dredge plume, while water is continuously pumped through the hybrid cable and winch to the topside LISST-200X. This unique setup delivers particle size, concentration (from laser as well as acoustic backscatter), and other pertinent parameters from the CTD in real-time as the sled is being towed and yo-yo’ed through the dredge plume from a vessel of opportunity. In addition to real-time measurements, this specialized system allows for co-located water samples to be collected on deck for ground-truthing sensor data.
Several FOAM systems are in use for moving vessel particle sampling, e.g., Chlorophyll sampling for harmful algal blooms in the Puget Sound, suspended sediment monitoring in the Caspian Sea, and oil spill response studies in Mexico.
Sequoia delivers LISST-Tau for eelgrass habitat dredge monitoring
A US customer took delivery of Sequoia’s latest product, the LISST-Tau transmissometer in 2021.
The customer reports that the instrument has already been critical for their work in pin-pointing turbidity exceedances from dredging activities in sensitive eelgrass habitats, and that the stability of the optical transmission measurements was reassuring and indicative of the instrument quality.