CVRD installs UV water treatment technology at Comox Lake

Jan 24, 2018

Originally published by the Comox Valley Record on Jan. 24, 2018 12:30 p.m.

The RD predicts the interim measure will reduce Boil Water Advisories by 80 per cent

Comox Valley residents have been waiting for the next Boil Water Advisory (BWA) to be issued by the Comox Valley Regional District.

But the BWA was avoided following the recent storm, much to the surprise and relief of people in Courtenay, Comox, and surrounding areas who get their drinking water from Comox Lake.

And now, we know why.

The CVRD finished installing a new ultraviolet disinfection system at its chlorination station in Comox Lake on Jan. 19, a few weeks earlier than expected. The two UV reactors — which cost the CVRD $400,000 — were originally scheduled to be installed in February.

Read More: New UV treatment to reduce Comox Valley boil water advisories by 80 percent

The UV technology is an interim solution to reducing BWAs until the CVRD’s new $110.6-million water treatment project is completed in 2021 or 2022. The CVRD budgeted $1 million to install and commission the technology last year.

Charlie Gore, the CVRD’s capital projects manager, says the UV reactors will act as a secondary level of disinfection for water coming from Comox Lake, which is currently only treated with chlorination.

“The problem with chlorine is it doesn’t inactivate some of the parasites that are in the water we have in B.C., specifically cryptosporidium and giardia,” said Gore. “The chlorine works well on viruses and bacteria, but not as well on parasites.

Read More: Comox Valley water treatment project receives green light

Gore says the UV light is at specific wavelengths that enter the cells of waterborne parasites and doesn’t allow them to infect humans.

“It doesn’t remove them, but it inactivates them or makes them benign to humans,” he said.

According to a CVRD news release, Island Health will likely issue amended operating guidelines for the Comox Valley’s water system in the coming weeks, allowing the UV treatment system to continue operating until the new water treatment system is operational in a few years.

The CVRD claims it will reduce BWAs by up to 80 per cent.

“The problem has often been the turbidity [in Comox Lake], which is measured in NTU, or Nephelometric Turbidity Units,” said Gore. “We’ll peak with a big storm and then linger between 1 and 3 NTU for many days before it drops to below 1, which is our current operating permit.

“What we’re able to do with the UV is create a condition where the water is safe up to a turbidity threshold of 3 NTU, which means a lot of the BWAs we’ve seen in the past wouldn’t have been issued.”

Courtenay director and Comox Valley Water Committee chair Bob Wells says the UV treatment technology will be able to be migrated over to the new water treatment system when it is finished.

“This UV reactor is actually sized for the new water treatment facility, which is going to be a bit larger, so it’s able to be a bit more potent,” said Wells. “Basically, we’re not just spending the money and leaving it, we’re going to be able to re-use that equipment.”

Read More: CVRD to host open houses on water treatment project

The CVRD is hosting two open houses on its water treatment project next week.

The events are open to the public and take place Monday, Jan. 29 and Thursday, Feb. 1 from 5–7 p.m. The first open house will be held at the CVRD’s boardroom on Comox Road, while the second will be at the Comox Golf Club.


Reporter, The Comox Valley Record