by Danny Zanbilowicz
There has been a great deal of speculation about the causes of recent high turbidity events in Comox Lake, which have led to inconvenient and expensive “boil water” advisories. Logging practices in the hills surrounding the lake are often cited as a likely cause.
The WORD had a recent conversation with Marc Rutten, General Manager of Engineering Services at the Regional District to find out the RD’s position on turbidity, and water treatment options.
Rutten says- “Regulations from the province of BC require us to follow standards. In 2007, the “4-3-2-1-0” guidelines were implemented within the province, and adopted by all the health authorities.”
These “Guidelines for Canadian Drinking Water Quality” (GCDWQ) are a national standard. Here are the guidelines from the VIHA website: “4 refers to a 4-log reduction in viruses: For every 10,000 viruses in the water, a treatment system should be capable of inactivating 9,999 of them. Most viruses are easily inactivated by the use of chlorine. • 3 refers to the 3-log removal or inactivation of parasites: For every 1,000 parasites in the water, a treatment system should be capable of removing or inactivating 999 of them. Two common parasites are Giardia and Cryptosporidium. To remove parasites filtration is required. To inactivate parasites ultraviolet light or ozone or chlorine. Turbidity and Filtration- View From the RD dioxide will need to be used. Health Canada has developed design guidelines to outline treatment methods which will provide the inactivation desired. • 2 refers to two treatment processes for all surface water or unprotected groundwater: There is no single treatment technology that can assure drinking water safety on its own. A minimum of two treatment barriers is required for water that is at risk of containing pathogens and that includes all surface waters and some groundwater sources. Filtration and disinfection will generally be required for most surface water supplies to ensure a safe supply of water. For systems with very high quality sources and effective and ongoing watershed protection, 2 forms of disinfection may be permitted. This will generally be chlorination and UV light disinfection • 1 refers to maintaining a turbidity of less than 1 NTU: Turbidity of less than 1 NTU should be maintained. Raw surface water will need to be filtered if turbidity readings indicate poor results. Turbidity is caused by particulates in the water and can generally be described as cloudiness. The health risk increases as turbidity increases and the health risk will increase before cloudy water is noticed.
Particles in water can include clay, silt, finely divided organic and inorganic matter, plankton and other microscopic organisms. These can limit disinfection or treatment and protect disease causing pathogens. For disinfection and treatment systems to be effective, the water must be less than 1 NTU. • O refers to Bacterial Indicators: Most of the viral, bacterial and parasitic pathogens that contaminate drinking water are shed from the feces of humans and animals. It’s not practical to test for each possible pathogen so an indicator organism (E. coli) is used to test for the possible presence of disease causing microbes. There should be “0” indicator organisms present in a treated water sample.
http://www.viha.ca/NR/rdonlyres/ F7669DB4-BA69-4EB4-A67A- 5EB050AC3857/0/drinkingwaterfactsheet- June2012.pdf
Rutten confirms that “Regulation is not open to discussion.” Filtration is a requirement. But a clause in the regulations says that if you have a very high quality source and if 95% of your water has less than 1 NTU you can apply for a deferral of a filtration system. Comox Lake is considered a high quality source.
The possibility of a deferral, and huge cost savings, was appealing to the RD- Rutten says- “We knew we were close, especially with a deep water intake. Currently turbidity enters Comox Lake from rivers, creeks and streams and travels on the surface. We convinced VIHA to do sampling and started collecting data in September of 2011. For the first two years- 2012-2013- we found we could meet the requirement, and be eligible for filtration deferral. VIHA agreed and said go ahead and do a deep water intake, along with a new UV disinfection facility. We started planning work for this in 2014. Then in October and December of 2014, there was a huge rain event with flooding, after a very dry summer.
Turbidity went up to 5 NTU- a record-breaking level. We saw turbidity at the deep water Intake sample station which was equivalent to or worse than on the surface. There was a boil water advisory for forty-seven days. VIHA reacted quickly, and sent us a letter withdrawing the filtration deferral. Now we need to go ahead. We are planning a filtration system to be completed in 2018, at an estimated cost of $75 million. $30 million is anticipated grant money. The remainder is funds we have in the bank, or new debt, probably funded with an increase in user rates.”
Rutten continues- “In mid 2015 we awarded a contract to Opus DaytonKnight for the study of water treatment options. The final report will be out in June. It will help us determine the most effective options- deep water intake, pump stations and locations, transmission mains, a filtration plant. There are lots of different combinations and the final recommendation will depend on several (environmental, social, technical and financial) factors including community values. We have had two public consultations, with lots of feedback, and one more on May 26. How does the community value water quality?”
As for the source of turbidity, Rutten believes numerous sources add to Comox Lake- “A major part could have come from Perseverance Creek. A couple of our employees determined that Perseverance Creek was very dirty during that rain event. An RCMP helicopter was filming the area, and when it flew over Perseverance Creek, there was a brown plume of water. An engineering analyst walked upstream along the creek and discovered a huge washed out area. We made the water committee aware, and informed VIHA, and received a request from VIHA to take action.” These indicators constitute a “smoking gun”, but Rutten admits no one has yet taken samples of the turbidity, to determine the source for certain.
He continues- “The RD does not own the land. What to do? On August 15 VIHA ordered the RD to remediate Perseverance Creek. The CVRD, Cumberland and Timber West all received orders. The order asked for two things- analyze options to stabilize the bank, or remove water from that part of the stream. Cumberland was already using a consultant, and banged off a high-level study, which showed all available options.”
Rutten adds- “Even if we resolve Perseverance Creek, it is not the only stream that brings in turbidity. In the future, another stream in the system may be ready to blow out. As a water purveyor, it’s all about protecting public health, and the need to follow regulations, and being effective in the long term. There are also several risks related to land use, such as logging. But land owners have rights to develop. We are trying to bring all the stake holders together, identify and categorize risks, and develop mitigating strategies.”
A complication with the turbidity issue is that the water running down Perseverance and eroding its banks seems to be coming from a source in the Cumberland water system, namely the spillway from Number Two Dam, going down an unnamed creek into Perseverance. It would be unfortunate if overflow from Cumberland’s water system was a significant source of turbidity for the water supply of the rest of the Comox Valley.
If so, would it be easy and affordable to fix? If not, it raises the possibility of Cumberland abandoning its system, and joining in with the rest of the Valley, at a time when Cumberland seems happier going its own way, and opting out of regional initiatives.
The next round of public engagement on the Comox Lake water treatment options study is scheduled for Thursday, May 26 as a late afternoon/evening open house (with slide show presentation, maps and displays and one-on-one question and answers). www.comoxvalleyrd.ca/water