Geotech Studies Underway
Photos courtesy of Moffatt & Nichol Engineering.
In September, the MCERP began conducting geotechnical studies at Rindge Dam in Malibu Creek State Park. The studies are an integral part of the pre-construction, engineering, and design phase of removing Rindge Dam.
These geotechnical investigations will help us better understand the century’s worth of accumulated sediment trapped behind the dam. Because of the narrow canyon and severely limited access, a Boeing CH-47 Chinook helicopter was needed to transport special equipment into the work area. Among the supplies air dropped in to conduct the studies were a drill rig, small excavator, front end loader, metal bridge, side-by-side ATV, tools and other supplies. Crews were waiting to accept the gear and begin mobilizing immediately.
Photo courtesy of Moffatt & Nichol Engineering.
Samples have been taken at several locations behind the dam to analyze the grain size of the sediment and saturation levels. They have been collecting samples at varying depths up to 100 feet before reaching the natural stream bed. Characterizing the grain sizes and other important material properties will aid in the design of where the material could be placed once removed, including on the beach, in the near-shore coast, or upland disposal.
For three weeks their workday began at 6 am to make the half-mile trek into the canyon and ended when the sun started to set to hike back out. The hike required wearing waders to cross chest-deep water in several locations.
The samples collected during these field studies will be analyzed by project team geotechnical experts. This data and the assessments will be incorporated into the basis of design reports and plan for removal.