Groundwater slows progress of Blakely Mountain tunnel

Apr 24, 2023

Miss Elaine was scheduled to reach the 2,000-foot mark of its half-mile journey through Blakely Mountain by Friday, according to documents the city of Hot Springs provided in response to a records request from The Sentinel-Record.

But the microtunnel boring machine named for District 2 City Director Elaine Jones, who didn't seek reelection this year and is retiring after serving 24 years on the Hot Springs Board of Directors, was more than 1,000 feet short of the milestone as of Thursday, City Manager Bill Burrough said.

"To date, Michels has tunneled approximately 824 feet," he said in a written response. Miss Elaine was scheduled to reach Lake Ouachita next month, but Burrough said the date has been pushed back to June.

The 2,600-foot, 60-inch tunnel Michels Corp. is drilling will allow water from Lake Ouachita to gravity flow 17 miles south to the new treatment plant the city is building off Amity Road. Miss Elaine, the MTBM designed and built in Germany specifically for the Blakely Mountain project, is the highest-profile piece of the Lake Ouachita water supply project.

City directors and staff took photos next to it and signed the outside when Michels brought it to City Hall in July. Some climbed inside its 5-foot-wide interior. Dozens, including elected officials and representatives from the U.S. Army Corps of Engineers, attended the Aug. 22 launching ceremony on the southern slope of Blakely Mountain.

The next day Miss Elaine's rotating head, bristling with 150-pound cutter teeth, began churning, clearing the way for a tunnel Michels said will be the longest of its kind in North America. The going was good the first few weeks. According to a payment request form Michels submitted, Miss Elaine had hit the 500-foot mark by September.

Reaching the milestone entitled Michels to a $3.18 million payment on the $19.27 million contract the board awarded it last year for the lake tap and intake portion of the supply project. The scope of work includes threading a 56-inch diameter pipe through the tunnel.

Installed in 240-foot sections via a thruster clamped to its outside, the pipe is being pulled through the tunnel by the thruster's two hydraulic cylinders and will eventually push Miss Elaine into the lake.

But the going got tougher as the calendar turned to fall. Michels told the city in November that groundwater Miss Elaine first encountered at 393 feet was becoming more of an obstacle as the journey progressed.

"Water has now been present throughout the entirety of the current mining operation up until current chainage of 742.78 feet," Michels said in an email to the city.

It said water was flowing at 600 gallons per minute, flows Michels said were more than twice the rate indicated in the geological report. Two-inch core samples extracted from the tunnel path in 2019 formed the basis for the report.

Michels told the city it was removing Miss Elaine from the tunnel and looking for spare parts.

Burrough said Thursday that a new drill press head tooled in Germany and Canada is now on site. It's designed for the harder, more resistant geology Miss Elaine expects to meet as it inches closer to the lake.

"They are far enough into the mountain to reach the harder rock, and the new drill head will be more conforming for this type rock," Burrough said.

Michels expected to be retrieving Miss Elaine from the lake this winter. The special activity permit it secured from the Corps of Engineers to stage its retrieval equipment at the Brady Mountain recreational area expires in February. Burrough said Michels is working on a permit extension.

The city has said Miss Elaine will be repurposed to bore the 17-mile raw waterline under the Mazarn Creek bed. The boring is part of the $14 million contract Michels was awarded earlier this year to float and sink the line across upper Lake Hamilton and bore it under Mazarn Creek.

The city had hoped to use the cheaper float and sink method for the creek crossing but was denied by Entergy Arkansas. The utility's license from the Federal Energy Regulatory Commission to use lakes Hamilton and Catherine for power generation gives it authority over the lake bed and construction and recreational activities on the two lakes.

Estimates used to size the $109 million bond issue the city floated in 2020 to finance the supply project didn't account for the expense of boring under the creek bed, an unexpected cost the city said added $10 million to the project cost. It's one of several project components that have exceeded estimates, ballooning what was a $106 million project two years ago to $151 million based on current estimates.

Boring a microtunnel through Blakely Mountain added $6 million to the lake tap and intake structure estimate. The city has said gravity flowing water through the mountain, rather than having to pump water over the top of the mountain's 1,100-foot elevation, will save money.

"We're paying more up front to save generations the cost of pumping over that mountain," Burrough said at the Dec. 1 news conference where he announced that new water connections would be suspended if the referendum on the rate increase the board adopted last month went forward. "It will save millions in the future."

Thursday's filing deadline passed with no referendum petitions delivered to City Hall, clearing the way for the city's underwriters to sell $45 million of new debt the city needs to cover the supply project's cost overruns.

Rate increases the board adopted last month to service the debt will go into full effect next November, raising base rates for residential customers inside the city by $4 a month. Residential customers outside the city will see a $6-a-month increase.

Print Headline: Groundwater slows progress of Blakely Mountain tunnel

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