This was a few years ago but the link is still active. Great little project we conducted in Lewistion Idaho. Gravity helped with the permits, coordinated the dredge contractors and conducted water quality monitoring during dredge activities. We had lots of local support……not a surprise considering that every other fisherman would run aground at the marina entrance!
Click here for story: http://www.klewtv.com/news/10984646.html?tab=video
Gravity is supporting a sediment transport study for University of Washington Graduate Student Maggie McKeon and advisor Alex Horner-Devine. This worked has included the install of an ADCP and overnight CTD and ADCP casts. Below is a brief study approach for this work:
Continuously modified since 1890, the Duwamish River estuary near Seattle WA has lost 98% of its intertidal area and accumulated enough legacy contaminants to justify four EPA-designated Superfund sites. Yet the estuary has retained a surprising amount of biological activity. The primarily hydrophobic contaminants sorb onto fine sediments and are concentrated in the bed, thus predicting the fate of the contaminants requires an understanding of the mechanisms suspending, transporting, and depositing the sediments.
Sediment transport processes are well studied in partially-mixed estuaries and the strongly stratified Duwamish provides an opportunity to examine these processes in a salt-wedge estuary.
We use monthly observations beginning in May 2011 to characterize tidal-scale hydrodynamic and sediment transport processes. We observe that low riverflow in the summer maintains the contaminated reach continuously within the salt-wedge. High winter discharges push the toe downstream, periodically exposing the contaminated bed to the higher stresses upstream of the toe. Measuring the present sensitivity of the system to tidal and fluvial forcing provides a framework to explore the impacts of sea-level rise and riverflow variability expected by climate change models.
Gravity has been working with local company Sea Engineering doing Vibracore work as part of a shoreline enrichment project. The seas have been good and the coring has been very successful. Retaining sands is always difficult but with Gravity’s proprietary “Hanz” lexan core fingers combined with our variable frequency coring rig we were able to get some great recoveries. It’s been Amazing working in Hawaii again and with snow falling in our home state of Washington it has been a real treat to be here alongside the dolphins and humpback whales that have been near us. Sorry no pictures of the sea life but I do have ones of our coring rig on the tropical waters here in Kauai.
Gravity is supporting a fish monitoring program on the Columbia River at the Hanford Nuclear site. One challenge with monitoring fish is getting a full river view when using a standard sonar and video camera system. Gravity’s Starfish sidscan can collect a bottom image 50 feet in width on each transect making it significantly more efficient to identify fish and target locations for video documentation.
Attached picture shows the sidescan pole mounted on our vessel
Gravity Staff have been called back to the MC wellhead location of the spill last year. Gravity is using its new Deep LISST (3000 meters!) and ROV camera system for viewing oil and bubbles. Gravity is supporting a SEEP study being conducted by a multi-disciplinary team of scientists.
See attached picture of CTD Rosette system combined with our Deep LISST and ROV controller.
Over the past few weeks we have been busy in the summer heat working hard on a multitude of tasks on the Columbia River at the Hanford site. We are teaming with Fowler General Construction and WCH doing in water curtain deployment from turbidity curtains to fish occlusion nets to a new acoustic sound avoidance system. Enjoy some of the pictures and look for more as we head out to Idaho for work with the Army Corps in the coming week.
