Oroville Main Spillway Failure: Will Shut Down, Press Access Restricted
AGENDA 21 RADIO
BY PAUL PRESTON
According to nationally known expert in dams Scott Cahill who has appeared on Agenda 21 Radio several times says the crippled main spillway and the system around it must remain functional through the runoff season or the dam could be compromised to the point it could fail.
The Department of Water Resources announced Sunday March 26, 2017 the main spillway on the Oroville Dam will be shut down and the Hyatt power plant will be brought back online.
Main Spillway Failure
The main spillway was shut down the first time on February 27, 2017 following the February 7, 2017 incident when a giant crater opened in the concrete spillway. Oroville Dam operators will halt water releases from the dam’s battered spillway Monday in order to ramp up efforts to repair the damaged spillway that have occurred since the restart of flows March 17, 2017 following emergency repairs that included drilling into the deck to force concrete into cavities created by high pressure water flows under the deck by water coming from leaks under the spillway gates.
Of big concern is how the flows from the shut down will be managed without doing down stream damage to river banks along the Feather River. Many ranchers and farmers lost large amounts of land that was washed into the river after the last sudden shut down of the spillway.
Of bigger concern to the DWR is the amount of damage that has occurred to the damaged main spillway since it was put back in service March 17, 2017 when water levels in the dam reached 865 feet.
High Pressure Porting
Agenda 21 Radio examined the damaged spillway Sunday March 26, 2017 on a press visit to the site and found large amounts of water being ported from the spillway training walls. Porting from the training walls is a sign there is water from the dam ‘pool’ under extreme pressure coming from under the spillway gates themselves. Water at pressure under the gates ports under the spillway deck which creates large cavities under the spillway which causes the spillway deck to collapse.
Chance of Dam Failure
Following the March 17, 2017 spillway continuation of water flows at the rate of 45,000 cf/s there was little evidence of porting from the training walls but it was evident to Agenda 21 Radio on scene at the spillway March 26, 2017 that the ports are now putting out water at high pressure, a sure sign the spillway gates are severely damaged.
According to nationally known expert in dams Scott Cahill who has appeared on Agenda 21 Radio several times says the crippled main spillway and the system around it must remain functional through the runoff season or the dam could be compromised to the point it could fail. Repairing the spillway during the shut down will be a major focus of the DWR as the levels behind the dam that have now dropped to 835 feet will begin to rise rapidly as the runoff season sends massive amounts of water into the Oroville reservoir. Bringing the Hyatt power plant online which was offline for weeks as debris was removed from the Thermalito diversion pond will help with outflows at 12,800 cf/s but will not match the current level of inflows which are reaching 46,000 cf/s.
Press Being Restricted
Agenda 21 Radio has traveled to Oroville Dam since February 11, 2017 on 12 occasions to report on the conditions of the dam. On our visit on March 12, 2017 we were advised by an employee of one of the dam contractors that reporters must wear hard hats and reflective cloths in the the designated press areas or face arrest. Agenda 21 Radio reporters passed by 3 check points manned by the California Highway Patrol and private security communicating at each one and was never advised to wear the hard hat and reflective cloths. A call to the DWR and check of their website revealed that reporters are now required to wear the hard hat and reflective cloths in all areas. DWR stated the ‘word’ had not gotten to everyone yet. Agenda 21 Radio is more than happy to comply with these additional requirements as they are seen as safety issues.
The big surprise was the denial of access to lookout portions of the dam which provide views of the work being done to a public facility. While Agenda 21 Radio was granted permission to view the spillway there was no access to the public viewing above the dam in the Kelly Ridge area that provides a view of the dam on the reservoir side. The entire length of the dam, water level and main spillway can be seen.
While standing under the dam at the base of the spillway several cement haulers could be seen going to and from the spillway area of the dam. Since Agenda 21 Radio was not granted access to the public viewing (under threat of arrest) area we are only left to speculate that since the porting has resumed on the spillway training walls the cement haulers were being utilized to make repairs to the failing spillway gates.
Hyatt flows stopped. Spillway flows stop Monday. @CA_DWR News Release, Sun. Mar 26th: https://t.co/5a9NIHl6zb #OrovilleSpillway #OrovilleDam pic.twitter.com/b7J5y7iQMD
— Oroville Dam (@Oroville_Dam) March 27, 2017
