OHL North America company OHL USA, Inc. (OHL USA), developed 14 dust-control areas on a 3.6-square-mile portion of a dry lake bed using locally sourced gravel cover, regional vegetation and sustainable shallow flooding for the $237 million Owens Lake Dust Mitigation
Phase 9/10 project.
The lakebed featured saturated, unstable soils which hampered the movement of rubber-tired rock slingers. The OHL USA team developed a low ground pressure rock slinger, equipped with rubber track chassis that provided necessary traction and prevented sinking. The four modified rock slingers helped move 800,000 tons of rock and form a 2-inch-thick ground layer over a 78 million sq. ft. surface area, achieving contract compliance with 20% less material. The scope of work also included nearly 45 miles of pipe installation for shallow flooding and to irrigate the newly-planted vegetation. Soft soil prevented the crews from digging standard pipe trenches, as the walls would likely collapse. OHL USA designed a “pipe boot” that enabled the team to simultaneously place pipe and bedding sand around it.
Near the end of the base contract, LADWP broadened the scope of work to include construction of three warehouses and a welding shop totaling 72,400 square feet of space. The project’s remote location complicated the task, as the nearest concrete batch plant was some 70 miles away. The team mitigated the issue by setting up a batch plant on site.
Owens Lake, a designated Nationally Significant Important Bird Area by the National Audubon Society and America Bird Conservancy, serves as a migratory stop-over site for shorebirds and waterfowl during spring and fall migration. The construction in the affected area continued after the birds leave the nest. LADWP’s dust mitigation efforts have significantly reduced the amount of harmful air pollution, with estimated emissions reductions totaling over 150 million pounds annually, transforming some of the nation’s dirtiest air into some of its cleanest.