FROM CRISIS TO CLEAN-UP WOLFPACK WOOD RECYCLING TACKLES TOUGH SPILLWAY SITE

Wolfpack Wood Recycling’s typical jobs include clearing for subdivisions and orchard removals. The site near the Oroville Dam was not a typical job.

The area near Lake Oroville in northern California had experienced one of the wettest winters on record in 2016-17. In mid-January, officials at the dam began releasing water down the dam’s main spillway, a 3,000-foot concrete chute that serves as the dam’s primary flood-control outlet during the rainy season. Multiple winter storms in early February caused the California Department of Water Resources (DWR) to increase the water releases to an estimated 50,000 cubic feet per second (cfs), well within the spillway’s normal capacity. Then a potential tragedy struck: a portion of the concrete gave way, opening up a large hole in the lower section of the spillway. In an effort to assess the state of the spillway, dam operators stopped the flow. Meanwhile, the water levels in the reservoir continued to rise and threatened to overflow onto the emergency spillway, essentially a lip of concrete directing water down an unpaved hillside adjacent to the main spillway.

Wolfpack Wood Recycling and other contractors were called in to help clear the brush and trees from the path of the water.

“They were worried at the time that, if the water came over the spillway, it would wash all of the trees into the river, and they did not want that,” said Tim Dempewolf, owner of Wolfpack Wood Recycling.

On February 11, four days after the damage appeared in the main spillway, water overtopped the 1,700-foot lip of the dam’s emergency spillway for the first time in its 48-year history, pouring in uncontrolled sheets onto the steep, wooded hillside to the Feather River.

“When I first heard that the water was going to come over the spillway, (my first thought) was ‘Get my stuff out first!’” Dempewolf said with a chuckle. He had a Morbark 4600XL Track Wood Hog horizontal grinder and 320 CAT excavator on the site.

“There were three other grinding companies working on the job site, so there were a lot of people trying to move pretty quickly. Everyone came together to get everyone out efficiently,” he continued. “Safety was a big deal, getting everybody out and out of harm’s way, and they did a good job.”

The next afternoon, the water caused erosion of the hillside below the emergency spillway and began to cut back towards the weir of the emergency spillway. Fears the emergency spillway structure would collapse and possibly send an estimated quarter of a million acre-feet of water down the Feather River caused the sheriffs in Butte, Yuba and Sutter Counties to order the immediate and mandatory evacuation of more than 188,000 people. The DWR increased water releases down the main spillway to 100,000 cfs, knowing it would increase damage to the structure, to lower the lake level and stop releasing water over the eroding emergency spillway.

“One of the key missions for California Department of Water Resources during this time, the initial first few days of the response effort, was public safety,” said Lauren Bisnett, DWR Information Officer. “And so, a lot of difficult decisions were made with the understanding that, to a certain degree, the level of some of the infrastructure on the flood-control spillway would probably be lost, but it was absolutely necessary in the interest of public safety, for the community here – downstream and those even further away.”

By February 14, the evacuation orders were lifted, and by the following Sunday, the water flowing out the main spillway had been reduced to nearly half of what it had been during the heart of the crisis. The lower flows allowed crews to use cranes and dredges to clear the debris that formed in the channel below the spillways. The debris raised water levels in the diversion pool and tailrace below the dam to the point that the Edward Hyatt Powerplant – the dam’s primary release outlet outside of flood season – nearly flooded. Hyatt could not be operated again until significant dredging and debris removal could be completed.

The Clean-up Begins
Dempewolf and other crews came back for the clean-up effort, Dempewolf clearing trees and brush to make room for the piles of dirt and debris other contractors were removing from the river, as well as clearing under power lines that had to be repositioned during the crisis.

“When I first started, it was just a hurry up, try to get stuff out of the way. Now it has calmed down, the lake is lowered down – now the focus is on getting everything in order so they can start fixing the emergency spillway,” said Dempewolf. “When I came back after the damage had been done to the emergency spillway, there were four or five additional big contractors in here, and everything has been running real smooth. Everyone knows what they are doing and have been watching out for everybody. Safety on this job is a pretty big deal.”

For a challenging job like this, Dempewolf said his choice of equipment is important.
“I wouldn’t buy a grinder unless it were on tracks,” he said of his Morbark 4600XL Wood Hog. “A lot of the work that I do is on hills and kind of steep ground, and if I had a grinder on a trailer – you would not be able to get around here. I purchased Morbark equipment because they have always had a good name and I’ve had nothing but good luck with Morbark grinders.”

Dempewolf said the strength of Morbark’s heavy-duty equipment is a key feature for him. “I’ve hit some pretty big chucks of steel with my Morbark – it held up. I was doing a project last summer out of Auburn, California, on a railroad job, and I hit some parts that came out of the railroad tracks – and it got into the machine and cracked hammers and tore up screens,” he said. “But it’s not a catastrophe if I hit steel. I’ve torn stuff up hitting steel, but I have never really completely damaged the machine.”

He said the same is true for Morbark parts: “They absolutely hold up better. I’ve ordered some parts from other companies, some of them are close in performance, but Morbark wear parts hold up really well. At one point when I was just starting out, I would get my wear parts from another company, because of pricing – they were comparable to Morbark and less expensive. But now Morbark is getting their prices more comparable, and their tips are getting better – at this point I’m sticking with Morbark parts.”