AGENDA 21 RADIO

BY PAUL PRESTON

Oroville – Explosives will be used to break up rock above the damaged main Oroville Dam spillway, although the Department of Water Resources says people aren’t likely to hear of feel the blasts.

In a press release, DWR said “The controlled blasting produces little to no audible noise or vibrations.”

The blasting is being used to set back the tops of vertical rock faces as high as 150 feet, that tower over the spillway and pose a significant risk for the people who will be excavating to reconstruct the spillway, according to DWR.

The blasting will be on an every other day schedule and last four to six weeks. DWR said it could have started as early as Friday.

It said seismographs will be placed throughout the project area to ensure vibrations remain at safe levels.

The department is also continuing improvements to Burma Road along the north side of the diversion pool, which will be one of the accesses to the spillway for the reconstruction work to go on this summer.

POWER LINES

DWR has largely competed moving the power lines to the Hyatt Powerhouse to a location believed to be safer. There was some fear at one point during the spillway emergency that the supports of a steel tower adjacent to the spillway might wash out.

The newer line is farther up the slop, closer to the gates at the top of the spillway.

PG&E also has a power line through the area, with a couple of towers in the potential flow area of the emergency spillway. It disconnected that line Feb. 10, the day before the emergency spillway was put into use, and temporarily relocated it farther west.

Starting Monday, the utility will start creating a permanent line, using helicopters to lift poles into place. Over the next couple of months, the towers in the spillway flow zone will be removed, a right of way will be cleared for the new transmission line, and eight new towers will be placed.

CURRENT CONDITIONS

Water is still be released down the damaged main spillway at 35,000 cubic feet per second. That rate of spill is expected to continue into the first week of May.

Inflow, in the 20,000-30,000 cfs range, has been lower than the releases and the Oroville Lake water level has been dropping. As of 4 p.m. it was just under 859 feet above sea level, down about 15 inches in 24 hours.

The flow in the stretch of the Feather River past downtown Oroville is 29,750 cfs, with another 5,000 cfs being added from the Thermalito Afterbay outlet.

No water is being sent through the Hyatt Powerhouse.

Oro-Dam Boulevard East remains closed from Glen Drive to Canyon Drive, and Canyon Drive is closed between Oro-Dam and Royal Oaks Drive. The road across the dam is also closed.

The parts of the Oroville Wildlife Area east of the river and Riverbend Park both remain closed. The area, roads and trails along the Diversion Pool are all closed as well.