SACRAMENTO, June 21, 2017 – The following is a regular update from the California Department of Water Resources (DWR) regarding Lake Oroville Spillways Emergency Recovery Project activities.
Continued Recovery Work on the Main and Emergency Spillways
- Construction continues at the site by DWR’s prime contractor, Kiewit Infrastructure West.
- Demolition continues on the bottom 600 feet of the upper chute of the main spillway.
- The final 1,000 feet of main spillway leading to the radial gates will be patched and reinforced, and will remain intact this year. This 1,000-foot section will be replaced and reconstructed in 2018.
- Demolition of the 1,400-foot lower chute of the main spillway is nearly complete, and crews are working on final cleanup of that area.
- Preparations are underway to construct the new foundation on the main spillway, which will begin in early July. Over the next two weeks, DWR will conduct test pours of concrete and build rebar forms to prepare for the spillway foundation.
- Crews are assembling forms and digging out trenches for the 1,450-foot secant pile cut-off wall that will be constructed 700 feet downhill of the emergency spillway.
- The roller-compacted concrete (RCC) plant has been up and running since June 17.
- Over the course of the project, crews will place approximately 800,000 cubic yards of RCC for both Spillways.
- The structural concrete plant (PCC), is expected to be operational by the beginning of next week. It is currently going through uniformity and mixer efficiency testing.
- Over the course of the project, crews will batch and place approximately 146,000 cubic yards of concrete from the PCC plant, which will also require the installation of 8.5 million pounds of reinforcing steel.
Heat-related safety measures
- Beginning Monday, June 19, Kiewit adjusted its 10-hour work shifts to start at 5 a.m. and 8 p.m. to avoid the hottest part of the day.
- Prior to each shift, crew leaders remind workers to look for signs of heat-related illness, point out designated shift monitors and establish a buddy system.
- During this heat spell, crews are reminded to stay hydrated, eating, and resting in the shade to prevent heat-related illness.
Installation of additional viewing cameras
- DWR is in the process of installing eight additional time-lapse cameras that will be located at various locations throughout the site.
- Information on how to access these cameras will be provided as soon as they are installed and tested.
Air quality control
- Because heavy equipment and controlled blasting at the Lake Oroville Spillways can cause dust plumes in the construction zone, DWR has measures in place to ensure compliance with all local and State air quality regulations.
- DWR is conducting continuous air quality monitoring, which includes dust monitors and an asbestos sampling apparatus located at the perimeter of the construction site.
- Representative air quality testing is also done during the process of drilling and placing controlled explosives, and all test results to date have been negative for asbestos.
- None of the airborne asbestos monitoring equipment set up at perimeter locations at have detected levels beyond established health-based threshold values.
- Crystalline silica may be present in the concrete chute blasts, but it is not considered a hazard to the public. Any airborne concentration quickly dissipates to a safe level.
- Construction workers are not required to wear respirators since measured exposure levels to date have been well below the California Division of Occupational Safety and Health (Cal/OSHA) permissible exposure limit.
Board of Consultants (BOC) Memo 7
- The seventh BOC memo was transmitted to the Federal Energy Regulatory Commission (FERC) on June 15.
- DWR reviewed the memo for Critical Energy Infrastructure Information (CEII), and no redactions were made.
- The seventh BOC memo and explanation of the role of the independent BOC will be posted to the DWR Oroville page on this week.