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Ask the engineers: Stave Lake project Q&A

AECOM engineer Angus English answers questions on the Stave Lake project. - Kevin Mills
AECOM engineer Angus English answers questions on the Stave Lake project.
— image credit: Kevin Mills

In two days, in addition to electing civic representatives, Abbotsford voters will decide the fate of a proposed water project to create a new water source and treatment centre at Stave Lake.

While there has been plenty of debate regarding the city’s intent to enter into a public-private partnership (P3) to build and run the facility, other questions have been asked as to whether Stave Lake is the best option, or if a new source is needed at all.

The News met with AECOM’s Angus English, the project director and final editor of the 2010 water master plan, and Tracy Kyle, the city’s director of water and solid waste, to discuss Abbotsford’s future water needs.

 

The AECOM report indicates the city could run out of water by 2016. However, average water use has decreased in the past few years. Are the projections still accurate?

English: One of the things that drives it is the maximum day demand. The maximum day demand is how much water we are going to take out of the system on that peak day ... If you exceed that, you’re diminishing your storage, diminishing your ability to fight fires.

The city has been very aggressive in putting in place a total watering ban. That had a huge effect on lowering the demand. In the absence of that, they’d be out of water.

So based on current projections, if you do nothing, you are going to run out of water ... Fortunately, since the time the report was authored, it hasn’t really been that great in terms of weather. People tend to water more in the front end of the growing season, May, June, July – they are the three big months ... It’s pretty unusual for this part of the world.

 

How are projections created?

English: In order to do the projections, you have to figure out where you’ve been. You go back and take a hard look at metered data ... Abbotsford is fortunate in that they have a meter base, Mission on the other hand is not. So Mission was a little greyer for us because we had to make some assumptions. Then you have to look at the population records that exist (2006 Census data).

I would be more inclined to look at population data and community growth data, rather than water consumption data.

I know the population is going to grow. It (dropping water consumption) could be seasonal anomalies; it could be weather-related. The average use is going to go up, simply because there are more people. If water is available and it’s hot outside, people are going to use it. Just on the basis of the head count alone, you are in a worse position today than you were when we started compiling the information.

 

Why did the report recommend Stave Lake over other water sources?

English: It met all of the water quality criteria. It was a good source of water. The capital cost and effectively the combined lifecycle cost, which is the operations and maintenance costs, was the lowest cost of the options. People ask, why can’t we do Harrison? Reality is, Harrison is a great source, but it’s a long way away with no customers along the way to help pay the costs for that extra pipeline. It just doesn’t make sense. We looked at Chilliwack Lake, we looked at the Fraser River ... wouldn’t it make more sense just to take river water and build the plant right there? Oh, but much, much higher treatment costs.

 

Why not just expand the current water system at Norrish Creek?

English: We looked at Norrish Creek. The capacity of the existing facility in terms of the licence – the licence isn’t big enough as it stands right now to fill the requirement. The costs of the infrastructure to get the water from Norrish Creek, through the system, was more expensive than what it was going to cost to do Stave Lake, especially when you added the cost of a new dam that would have to be built. The facility as it exists today would need a substantial revamp in order to get the capacity through the facility to meet the requirements.

Kyle: Norrish is also a small watershed and it would only give us another 10 years. So when you’re looking at a 25-year planning period, you do the work at Norrish and you’ll still have to go to Stave Lake.

 

Could Cannel Lake be used as a water source?

English: It has an extremely small watershed. It already has a limited licence on it ... There simply isn’t enough water that feeds that watershed.

 

Was the Abbotsford-Sumas aquifer considered as an option?

English: Not specifically no. As soon as you go beyond 75 litres a second you trigger an EA (environmental assessment). The quantity of water we are talking about will require multiple well fields.  Is it ground water or is it surface water? You would have to treat it to the exact same standards as you would surface water. It’s not necessarily a slam dunk for wells. With a 20-year horizon and probably 200,000 people, banking on well fields is not generally the way to go.

 

The AECOM report estimates the cost to be $209 million to create a Stave Lake water supply. Now, 18 months later, the city has revised the number to $328 million to build in the traditional manner (non-P3). How did the price jump so dramatically?

English: I asked the same question: how can this possibly be? We don’t understand because our estimate, we were pretty certain, was representative of what it could cost for what we had written in the report. They (the city) upsized the transmission main, took a more conservative assumption on treatment. There was a decision that they wanted to have a tunnel for the lake intake. We hadn’t contemplated that that would be necessary. So those things added substantial costs to the project.

 

Will Abbotsford run out of water by 2016?

English: Yes. Looking at the demand projections, even if a full sprinkling ban is in, even if the Bevan Wells are online (providing an additional 20 MLD) if the customer behaviour stays exactly the same, you will be without water by 2016  (on peak-use days). On those days we can’t guarantee we are going to be able to give you supply.

 

Questions to Kyle:

Has the city obtained a water licence for Stave lake and what will it cost?

Kyle: We have submitted the application to the province and we are working on terms with BC Hydro (which currently own the licence). We basically have to compensate Hydro for its lost generation. They won’t be making a profit – it’s a nominal amount.

 

Is it true that the water level at Stave Lake has to be lowered every few years and will that affect our water supply?

Kyle: There’s a Stave River water use plan and that dictates the water levels that need to be in Stave Lake for fisheries, for recreational purposes and for First Nations.

That plan states that every few years, BC Hydro has to draw down Stave Lake to accommodate some archeological research and digs along the area that’s currently flooded. We know about that and it’s for that reason that we’re placing our intake at the lowest part of the original river bed ... we will still be able to get water.

 

Will a private company be paid for 100 MLD even if we don’t need that much water?

Kyle: We know that we are going to want to use our Norrish Creek water, first priority,  because we don’t have to pump that water. Some years, especially near the beginning, we aren’t going to need a lot of water from Stave Lake on an ongoing basis.

So they (a private partner) are going to know that up front. We’ll be structuring how they put in their proposal. It will have a base rate for basically making the water available, so making sure there are 100 million litres a day available, should we need it, whenever we need it. There will also be a component for what we actually use.

So we are always going to be paying for what we actually use.

 

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