The engineer is starting the design for the upgraded Irrigation Lake dam.
Carl Pentilchuk, Water Resources Engineer, was contracted by stakeholders in July to look at the Irrigation Lake dam and develop a design for the government required upgrade.
Funded by the Bulkley Valley Credit Union, Pentilchuk surveyed the dam last Wednesday and collected site information needed to develop a design – which should be complete this December.
“The dam is in terrible shape and it’s rightly condemned,” Pentilchuk said as he did the survey.
“Everything has a serviceable life, and this dam has exceeded it’s serviceable life.”
But Pentilchuk says the upgrade should be quite straightforward, and a good portion of the existing dam can be reused and built upon, which will save on costs.
Pentilchuk says it’s very hard to estimate a cost at this point, but if one was to hire a contractor to do all of the work – with no volunteer help, volunteer equipment or donated materials – it would cost close to $80,000.
But stakeholder representative Steve Page says they are hoping for and expecting volunteer help.
“When we have the approved design, we’ll be asking many people to volunteer time, equipment and materials.
“It is the hope of stakeholders that donations can be made to reduce [the $80,000 cost estimate] as much as possible,” he said.
One issue with the current dam is that the top layer is made of earth materials which can easily erode and get saturated with water, weakening the entire structure and possibly leading to a dam blow out.
Pentilchuk says that when they upgrade the dam, they will dig out the top layer of earthen material until they reach the foundation of solid material.
They don’t know how the dam was built, so they will find out as they start digging how much they will have to dig up and how much they can reuse, Pentilchuk said.
The upgraded dam will fit safety standards, be built of solid material, and will be much bigger – an estimated four metres wide, 70 metres long, and 2.5 metres high (up from the current 1.8 metres and one metre above the water level in compliance with the safety standards), he said.
Pentilchuk says another issue with the current dam is that there is a gate controlling the amount of water flow, and there is no way for water to come through the dam unless somebody opens the gate.
“If the lake gets too high and nobody opens the gate, it will over-top the dam.
“In today’s standards, you need a means for water to just naturally escape. If nobody comes here, the water needs a passage,” Pentilchuk said.
He says part of his design will include an earth channel on the west side of the dam, which will be at the licence level of the lake and one metre deeper than the dam.
Pentilchuk says his design will be finished in December, and he will report back to stakeholders and to the Water Stewardship Division for approval.
If they get approval, construction should begin next spring, Pentilchuk said.
Page says they plan to lower the lake by half a metre next June, July, and August for the dam construction.
Even with the lake lowered, swimming at Irrigation Lake Park and at the two summer Bible camps will be able to continue, and the two geothermal systems used by the camps can continue to function, Page said.
He says they expect the lake to fill back up over the winter and spring following construction.
“Going into the future, the lake should look the same as what it’s looked for the last many years,” Page said.
Wendell Garrison, Director of Rock Nest Ranch on the north side of Irrigation Lake, says he is very pleased with Pentilchuk’s plans and ideas.
“I think it’s very do-able,” he said, adding that the plans sound very similar to what the stakeholders had previously discussed.
“Without giving him any information, [Pentilchuk] looked at the site and came up with a very similar solution,” said Page, adding that it eased a lot of fears about costs.
One issue that remains in the air is who will take on the water licence with it’s liability and responsibility for dam maintenance and upgrades.
When the Ministry of Forests, Lands and Natural Resource Operations threatened the dam removal back in June, they required a new licence holder and an engineered plan for dam upgrades.
Stakeholders met to discuss the licence at the end of July, but no one would take on the licence without information from the engineer study and a cost estimate for the required upgrades.
Page says stakeholders won’t decide on the licence holder until they have the final design in December.