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Reservoir or aquifer? Test well will tell tale


Cornelius needs additional capacity for water storage

by: NEWS-TIMES PHOTO: DOUG BURKHARDT - Cornelius currently has just one aging water reservoir with a capacity of 2 million gallons. As part of its agreement with Hillsboro, however, Cornelius will be required to expand its storage significantly with either a new reservoir or by tapping an aquifer.Facing the reality that it has too little water in storage in the event its supply gets cut off in an emergency, the city of Cornelius is gearing up for a major investment in its water-system infrastructure.

“It is common for municipal water systems to have several days of backup water supply in the event of a water supply system breakdown,” said City Manager Rob Drake. “The backup is severely inadequate. It only makes sense to require some backup in the event of a temporary cutoff of supply for a line break or repair.”

Currently, Cornelius has just one water storage tank, which has a capacity of 2 million gallons — not much for a city that uses about 1 million gallons a day on average and about 1.5 million on peak days in the summer.

With a new water reservoir needed, the question becomes: what type of storage facility should it be?

The original concept, approved by the Cornelius City Council last year, was to build a second above-ground water reservoir near the site of the existing one, in appropriately-named Water Park. But Drake is suggesting an alternative that might be a wiser, more cost-effective approach for the city.

Rather than building another reservoir, Drake proposes tapping an aquifer under Cornelius.

With what is known as the “aquifer storage recovery system,” treated potable water would be injected into the ground between layers of rock. Following this concept, millions of gallons of potable water could be stored underground and used during times of peak consumption in the summer.

“Tapping into the aquifer itself would cost $1.6 million,” Drake explained. “A 2-million gallon reservoir costs about the same — about $1.6 million — so to me it made sense to hit a home run with more storage capacity.”

Without drilling, engineers can’t be sure how much water might be in the aquifer, but city officials believe it could be a substantial source.

“We’re hoping there will be maybe a 25 million gallon capacity underground, in lieu of building a 2 million gallon reservoir for roughly the same price,” Drake said.

A test well will be drilled this summer or in the fall to establish how much water is actually there.

In all, the project is expected to cost roughly $2.8 million, because with either a new well or an above-ground storage reservoir, there would need to be some upgrading of water pipelines in the area.

Drake pointed out, however, that state and federal grants are likely to be available through the Clean Water Act. The grants could cover about one-quarter of the project cost up front, and the rest would be financed.

Water from Hillsboro

Cornelius purchases its water from the City of Hillsboro, an arrangement that has been in place since 1941.

Although Cornelius Mayor Jef Dalin recently said the city was in the process of “evaluating current water sources to seek either our own water source ownership and/or less expensive long-term water purchases from a new wholesale supplier,” those goals appear to be just a “wish list” at this point.

According to Drake, it’s unlikely the city would be able to find a better deal than its current water supply agreement with Hillsboro.

“There are a lot of unknowns and a very long-range look,” explained Drake. “We have no water rights and nothing firm.”

The latest five-year water contract with Hillsboro expires at the end of 2013, but Drake does not see any reason why the deal would not be carried forward.

“It’s safe to say it will be renewed,” Drake said. “We’ve had a good relationship, and it’s high quality water.”

According to Kevin Hanway, water director for Hillsboro’s Water Department, the city’s primary source of water is the Tualatin River.

“We take water from that year-round, and from Hagg Lake in the summer,” Hanway said.

Just this month, the City of Hillsboro announced that it will eventually take water from the Willamette River.

“The Willamette River has been identified as our preferred source for expanding,” Hanway said. “The current plan is to come online (with Willamette River water) in 2026.”

Drake pointed out that with a growing population, water is likely to become an increasingly troublesome issue for Hillsboro and Cornelius.

“It’s not easy finding water sources as we get thirsty and populate more,” Drake said.

Hanway pointed out that added storage capacity is a requirement of the water contract Cornelius has with the city of Hillsboro.

“We are a member of the Joint Water Commission, which sets policies all members are required to follow,” Hanway explained. “It’s a requirement of all partners that we have a certain amount of water storage. It’s a good goal and a good part of water system planning, but there is no deadline for Cornelius to do so.”

The Joint Water Commission recommends that water systems have enough storage to get through three average days’ demand on the system.

The commission encompasses Hillsboro, Forest Grove, Beaverton and the Tualatin Valley Water District, which serves the unincorporated area between Hillsboro and Beaverton, including Aloha and Bethany. Cornelius is not a member of the Joint Water Commission because its supply comes by way of its contract with Hillsboro.

Hanway added that the water contract is considered sacred.

“The contract is a mutual agreement,” Hanway explained. “They (Cornelius) agree to buy water from Hillsboro, and Hillsboro promises to meet their needs. That’s a very serious commitment. We include Cornelius’ demand in our water supply planning, and make sure their water supply needs will be met long into the future.”

Even with all the growth Hillsboro is projecting and the needs of Cornelius, Hanway said he is optimistic there will be no shortages in the foreseeable future.

“Current sources of supply are projected to be adequate to get us through the next 10 to 12 years,” said Hanway.