Guarding the gabion

 Guarding the gabion

The consultant in charge of setting up the temporary dikes on Farrell Street said he is just as annoyed some homes couldn't be protected from potential floodwaters, but that it wasn't in his power to make it happen.

 
"It was a question of it wasn't possible, it wasn't feasible, I couldn't get my men and equipment in there and if I could, I'd still be - in my consideration - putting the workers at risk because I'd be overstressing the soil on the bank and the dike may collapse under them," said Neil Hamilton, a provincial floodplain management expert working with contractors Surf-Tec.
 
Last Thursday, the city installed 900 metres of temporary diking in the form of gabion baskets on Farrell Street. Gabion baskets are a quick-diking system that uses foldable wire-mesh containers five metres long, one metre deep and one metre wide.
 
These can be rushed to trouble spots, unfolded and rapidly filled with sand by front-end loaders, creating new dikes more quickly than traditional sandbagging.
 
The province owns the system and loans it to municipalities for free. When not in use, the majority of it is stored in a Lower Mainland facility, but there is also a 1.2-kilometre cache stored locally in Prince George.
 
"Emergency Management BC authorized and covered all expenditures (materials and labour) associated with the installation of the temporary diking (gabion baskets) on Farrell Street. There was no cost to the City of Prince George," said city spokesperson Chris Bone in an email.
 
But some residents expressed dismay over the placement of the wall, which locked their homes in on the same side as the rising Fraser River.
 
"It was assessed, honestly," said Hamilton, who arrived in Prince George on June 6 to begin consulting with city staff. He has made numerous trips to the area over the past five years to deal with other flooding issues. The same diking system was used to stem the waters of the Nechako River during the ice jam in 2008.
 
"I understand why the residents are concerned. They think they're being avoided out. I tend not to, in any cases where I build dike, build them right on the edge of the river because as soon as the erosion moves anywhere, you've lost all your level of protection."
 
That protection would not have made a significant difference to homes behind the wall if the waters rose, according to Hamilton.
 
"The [water] would still come through and it would come in to pretty much the same elevation. It's not like it was going to be spread out over an extra five mile of flood plain that I prevented. There was probably an extra 100 feet of floodplain," he said. "To those homes on the outside of the dike, yeah they would be getting wet, but they would have gotten just as wet anyways if the dike hadn't been there. It's not like I'm making their situation worse."
 
Hamilton said that not only was there not enough room between the rising Fraser and the riverside homes on Farrell Street to safely work with the necessary heavy machinery, there wasn't enough the time.
 
"If I had three or four days, and I could do everything by hand, yes we maybe could have applied protection," he said. "But when I'm looking at flood waters that are supposed to hit the crest in 12 hours of the time that I arrived on site, I'm doing machine work ... In my professional opinion, from years of experience, and in the experience of the professional engineer that was also on site, it wasn't a question of stupidity - it was a question of 'we just can't do this.'"
 
Using sandbags was also out of the question, according to Hamilton, who said it would take thousands of bags and several hundred volunteers to get them in place over a period of four or five days.
 
"If you've got four or five inches [of water] sandbags are the ideal thing to do. You circle the house, you build them up one or two [bags] high and they last really well in that condition and do a great job," he said, adding getting a three-foot high barrier is a more skilled task to ensure it doesn't fall over.
 
Throughout the previous week, volunteers from the Drug Awareness Recovery Team (DART) loaded about 4,000 sandbags.
 
"Those sandbags would build me 100, maybe 150 feet of dike. That's it," Hamilton said, adding he had nothing but praise for the DART crew. Those same volunteers also worked through the night last Thursday to construct the temporary dike.
 
"They are the hardest working crew I've ever come across," he said.

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