Mike Carter, Chetwynd Echo
CHETWYND – The District of Chetwynd is continuing work to adjust the effectiveness of its sewage treatment lagoons, which were found to be in violation of the provincial Waste Management Act.
A letter of warning was sent to the District from the Ministry of the Environment in early February that explained lab samples had showed discharges of effluent into the Pine River that exceeded the maximum authorized limit for five-day biochemical oxygen demand (BOD).
These samples were taken from the lagoons between December 2012 and February 2013. Further exceedances of the permit were also discovered in early March.
A discharge permit, issued to the District under the provisions of the Waste Management Act, states that the effluent leaving the sewage lagoons is not to exceed a BOD level of 30 mg/L.
According to the former Environmental Protection Officer (EPO) for the region, Ann Godon, the levels of BOD discharged late last year and in the early part of 2013, were “two to three times higher” than that amount.
“ December wasn’t a big exceedance but in January it was fairly significant,” Godon said, later adding, “there were BOD exceedances in February and early March that we referred to the conservation officer.”
The Ministry of the Environment noted that it was possible the discharge of effluent containing above normal levels of BOD was acutely toxic to fish species living in the river.
What is BOD? The presence of a sufficient amount of dissolved oxygen in a body of water is integral to the survival of fish and other forms of aquatic life.
Determining how organic matter affects the concentration of dissolved oxygen in a river or lake is therefore integral to water quality management.
Biochemical oxygen demand or B.O.D is the amount of dissolved oxygen needed by microorganisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period.
The term also refers to a chemical procedure for determining this amount.
These microorganisms turn wastewater into clear water through the biochemical action the bacteria performs on the waste.
This water run off then leaves the lagoons treated and is discharged into the river possessing sufficient amounts of dissolved oxygen for aquatic life survival when the treatment process is effective.
The five-day BOD test is a commonly used method of gauging the effectiveness of wastewater treatment processes.
The standard oxidation test period for BOD incubates samples from the lagoons for five days at 20 degrees Celsius. The reported level of BOD is used for many applications, most commonly to indicate the effects of sewage and other organic wastes (plant decay and leaf fall) on dissolved oxygen in surface waters.
As part of the requirements of the district’s discharge permit, monthly samples are taken and forwarded to the Ministry of the Environment.
While on average it takes 42 days for incoming sewage to leave the lagoons as treated water, the five-day BOD test provides a rapid way of knowing what levels of oxygen exist in the lagoon, and as a result, what levels of anaerobic action are happening to break down the organic matter.
A higher than normal BOD count in effluent leaving the lagoon system creates a stress on the Pine River by lowering the levels of dissolved oxygen in the water, which can possibly kill aquatic life.
“It’s all about good bugs and bad bugs,” Gordon explained. “The good bugs need oxygen to live. The bad bugs eat too much oxygen and the good bugs die.
So somebody could have dumped a high BOD concentrated load in [our lagoons] and taken all the oxygen out, but I can’t point fingers and I can’t name names, you just have to [use] science to try and back track.”
The Root of the Problem
Typically in the winter, the lagoon system sees higher counts of BOD in its effluent discharge than it does in the summer, however these amounts do remain below the required parameters of the discharge permit.
These levels rise in the winter because the ice on the lagoons, and the jamming of the irrigation fountains by additional snow and ice build up, causing the levels of oxygen in the lagoons to drop and the amount of oxidation that occurs to lower.
This season, the District had five out of the ten irrigation fountains rendered unusable.
“We [commonly] struggle through the hardest months of the winter to stay within the parameters,” Gordon stated. “However, this winter something happened where our numbers actually got quite worse, which means the [lagoons] were in distress. There wasn’t enough oxygen in the lagoons for the bugs to do their job, plus the fact that the first two cells had a large amount of sludge in them.”
The resulting discharge into the Pine River exceeded the BOD count of 30 mg/L, sending off alarms with the Ministry of the Environment.
“Our office expects compliance with the permit at all times,” former EPO Ann Godon acknowledged. “I would like to be able to say [Chetwynd is] back in compliance but there is the possibility of future investigation. They are taking steps, they are working towards it. Sewage treatment systems don’t improve quickly, and they can take time.” Public Works manager Paul Gordon stated that finding the root of the problem hasn’t been easy. It could have been due to the fact that winter started early, or there could be a problem with more flow going into the lagoons than they could handle. “[We think] with the combination of the sludge and the lack of oxygen in the water, the flows were basically going through the lagoons too fast, not getting the entire treatment, so [discharge was] outside of the proper parameters with the province.
“It could have been winter, but this year the numbers spiked a little to high, it didn’t make sense typically so we just thought, either we’ve got too much flow going in here or maybe somebody dumped something in here, these commercial haulers because its possible, even without their knowledge they could have dumped something detrimental,” Gordon said.
“[The Ministry] has since sent a team up here and they’ve sampled the lagoons and they’ve sampled all the people that have been dumping in the dump station, because it could have been anything.”
Mending the Mess
Without knowing exactly what the problem is, certain steps have been taken by the district to repair the weakened lagoons and alleviate the stress on the river. Step one was lowering the amount of flow coming into the lagoons by closing off the sewer dump station, which is used by commercial septic tank cleaners, industrial work camps such as Walter Energy’s Grizzco camp located by the airport, and RV campers.
“Council passed a motion allowing me to close the sewer dump station and those people are now taking their stuff to Dawson Creek or Fort St. John,” said Gordon.
Step two was hiring a professional to study the lagoons and report back with some recommendations.
“I hired an engineer from Golder and Associates to tell me just what the heck was going on this year, to help us figure out what happened to our lagoons. Why aren’t they functioning as well as they should and to help us get back within our permit requirements. You have to understand that if the Minister of the Environment doesn’t like what we are doing, they very well could hit us with very hard penalties, so that’s why I sort of declared an emergency situation, I hired this company right away.”
The next step was to bump up de-sludging work on the lagoons that was scheduled as regular maintenance in June. This work was completed mid-March.
The district is now obliged to submit three consecutive reports to the Ministry of the Environment showing complete compliance with the permit before the possibility of further investigation and financial penalty can be taken off the table.
“I know we aren’t quite there yet, but I know we are on the right track,” Gordon said.
The report from Golder and Associates is expected mid-May.
“That report is going to tell me what happened exactly, did somebody do this to us or was it a naturally occurring event?
“We had to take it very serious because there’s very heavy fines from Ministry if [we were] not in compliance with our permit. I got 100 per cent support from administration here and from council, everybody acted as a team and we’ve gotten through the worst of it. We are recovering and we are awaiting the final report to see what’s happening