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Assembly looks into Salmon Creek filtration

Posted: April 10, 2012 - 12:04am

Salmon Creek filtration could be the route the City and Borough of Juneau goes to make its water system redundant.

The city Assembly met as the Committee of the Whole on Monday and received an update on the AJ Mine Related Water Study from Engineering Department Director Rorie Watt.

He reviewed the 80-page report for the Assembly and said he felt good about the questions and feedback he’d received from the public. Assembly members expressed interest in investigating further options with increasing Salmon Creek’s capacity. After Watt reviewed the report, Mayor Bruce Botelho asked if members would object to entertaining a draft resolution that largely incorporates Scenario No. 4 — rerouting the Gold Creek drainage tunnel and adding filtration to Salmon Creek. Botelho said this wouldn’t establish a timeline or funding source, however it would give the public an opportunity to comment on the idea and give the city the opportunity to research and develop the idea further.

“I would be interested in reading a resolution and thinking about it,” said Assembly Member Randy Wanamaker. “I am not sure I would support it. I have to see it and understand it.”

Assembly Member Carlton Smith said he would like to see a “final” stamp on the report and a recommendation from the new city manager before they go forward with a recommendation on water improvements.

“Whatever scenario we ultimately approve is going to be a substantial amount of money,” Smith said.

Assembly Member Karen Crane said she wanted to see the water piece go forward before any mine options are taken into consideration.

“For me, I’m not willing to go to a next step until we have a plan for this,” Crane said of the water system. “Until we can say to the public, ‘this is where we’re going, and this is the plan.’ We heard from many, even those who were pro-mine, that water was an issue for them.”

Assembly Member Ruth Danner wanted to see the phrasing re-worded for the scenario — supporting creating a filtration system at Salmon Creek and only rerouting the drain tunnel if the mine property is leased to a mining operation.

Danner said then the city would show commitment to upgrading the Salmon Creek water supply regardless of mining activity.

Botelho said now would be a good time to start looking into the option, as the 1 percent temporary sales tax initiative will be up soon and the city is putting together its five- to six-year Capital Improvement Project plan.

Assembly Member Jesse Kiehl wasn’t sure what the resolution would resolve. He said it wasn’t clear they would need a filtration system at Salmon Creek if the Gold Creek tunnel wasn’t rerouted.

Smith asked Watt what areas of the report he still wanted to provide more information on.

Watt said he would like to include more information on filtration system operating costs; get more research on low-flow periods in correlation with turbidity events, Gold Creek flow events and the probability of extreme low-flow events; and get information from Alaska Electric Light & Power on Salmon Creek Dam issues. Watt said he also would like to continue keeping the public up to date on information with the report.

In Watt’s explanation of the report to the Assembly, he discussed again the water rights between AEL&P and the city, the power company’s dam situation, and resource flow issues.

Watt said while the city hasn’t had a significant issue in the past, he could foresee a water supply issue eventually. Watt said if that event occurs, it could mean water rationing or using up reserves — which would mean low capacity for fire fighting.

“When you run the math 30-50-100 years, it does seem like a very real possibility,” he said.

Watt explained AEL&P does have the senior water rights because the company was there before the city. He believes if there was an issue the city would actually get preference with the state because it supplies drinking water, but he believes some kind of restitution would be owed to the power company if that ever came about.

Watt said AEL&P’s water right to Gold Creek generally “eclipses” the supply at the creek, however the company doesn’t have the infrastructure to use all of its water rights.

“During their typical water production period, they’re using perhaps 2/3 of their water right,” Watt said. “I would not say we are at all in conflict with the way we manage the water shed.”

Rerouting the drain tunnel, Watt said, could also be problematic with supply in some cases.

“One implication I want to highlight at this moment, if removed from the water field, it could exacerbate water consumption during low-flow periods,” Watt said. “During winter months we’ve seen less flow in Gold Creek than the city uses for drinking water. That hasn’t provoked a problem or a crisis in the past. There is some quantity of water stored in the aquifer, so that is a point of discussion. How much water can we afford to lose in Gold Creek?”

Watt said AEL&P doesn’t operate during those low-flow periods.

“The allocated flow is less than the flow of Gold Creek 70 percent of the time,” Watt said. “That’s been true for well over 100 years.”

Crane asked about the Salmon Creek Dam.

Watt said AEL&P acquired it from AJ Industries and it is regulated by the Federal Energy Regulatory Commission. He said they relicensed the dam in the 1980s, and at that time they were required to undergo an earthquake analysis. That analysis found if there were an 8.0-magnitude earthquake at Point Retreat, the dam would not fail, but would suffer structural damage if it were full of water. So AEL&P dropped the water level 30 feet. It still holds 3.9 billion gallons of water.

“That lowering of 30 feet allowed them to theoretically not fail and not have structural damage,” Watt explained. “It’s been time for another relicensing of the dam. They have damage engineers looking at the issue. They told me when they get the results they would like to come and present because it is a community issue, not just an AEL&P issue. The dam is weathered a bit more in the last 25 years. I don’t think we’ll see something catastrophic (in the relicensing report). Lowering the pool would be most likely outcome.”

Watt believes the dam will be a part of the community for the foreseeable future, especially since AEL&P, the city and DIPAC (Douglas Island Pink and Chum) have agreements to keep it up.

Watt’s recommendation for the Assembly if it is to go with enhancing the water system is for more research on the options. Watt said there isn’t a whole lot of information on the issues for water sources at Mendenhall Valley — though test samples were taken and the water was brackish in areas. For Salmon Creek a filtration system designed to meet city needs would also need to be researched. The one listed in the report supports 4 million gallons per day, however in peak periods the city uses upwards of 5 million. Watt said for the report, the 4-million-gallon plant was used as a ready example because it is a common facility made by a leading manufacturer.

The proposed resolution will come back to the Committee of the Whole for discussion before it is introduced to the Assembly’s acting body.

• Contact reporter Sarah Day at 523-2279 or at sarah.day@juneauempire.com.

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