Squamish landfill's runoff now ends up at the district's sewage plant, a move some environmentalists say threatens the lower reaches of the Squamish River and the Howe Sound environment.
With the $2 million landfill expansion and environmental upgrades complete, District of Squamish officials on Monday (Nov. 21) opened the pipe that will funnel liquid that has seeped through the trash to the town's wastewater treatment plant. That liquid, know as leachate, can be contaminated.
In 2008, the Ministry of Environment issued the municipality a "non-compliance" certificate because polluted refuse water was leaking into the soil surrounding the dump. The new expansion is lined with 9,000 square metres of plastic sheeting to catch the leachate before it's piped to the treatment plant. Other parts of the landfill, which opened in 1978, will also be covered in the same plastic lining to help reduce the amount of water travelling through the 20-metre-high mound.
Local environmental watchdog John Buchanan, though, claims sewage treatment plants aren't equipped to deal with the types of toxins found in landfill leachate. In 1984, then-Squamish mayor Jim Elliott was quoted in the Squamish Times warning council of the threats of lawsuits if leachate reached the Squamish River. Now the district is doing just that, Buchanan said.
"I am really concerned that the dump has a direct line to the ocean," he said.
Even if landfill liquid releases a minimal amount of toxins into the river, Buchanan said he wants to know what effect that will have over time.
Buchanan said he would like to see the district treat the liquid on-site, a process he said is recommended by scientists.
"The sewage treatment plant is not set up to handle chemicals and heavy metals," he said.
Sperling Hansen Associates, which prepared a report on Squamish's landfill leachate treatment, recommended the district send the landfill liquid to the Mamquam Wastewater Treatment Plant. On-site disposal was estimated to cost $3 million to build and $175,000 annually to operate, while infrastructure to divert the leachate to the treatment plant cost $1.1 million and $15,000 annually to operate, stated the report.
The new landfill is anticipated to generate 7.5 litres per second of leachate a day, said Rod MacLeod, the district's solid waste project manager. That amounts to an approximate one per cent increase in flow to the plant.
The liquid will be heavily diluted in the wastewater stream, he added.
The leachate is not expected to affect the hydraulic capacity of the plant or its ability to meet limits for biochemical oxygen demand and toxic shock syndrome, stated the report. The treated leachate is anticipated to generate five per cent more sludge at the plant, with the sludge transported to Whistler to become compost material.
The runoff from the dump will be tested at both the landfill and at the wastewater treatment plant, said Tony Sperling, president of Sperling Hansen Associates. A lot of the metals found in landfills are common in the environment, he noted.
Generally, municipal treatment plants are effective at processing leachate, particularly when it is a relatively small percentage of the flow into a wastewater treatment plant, said Jim Atwater, UBC civil engineering professor.
Once landfills start producing methane, the dumps have a neutral PH or are slightly alkaline, he said. With the exception of iron, there are also usually fewer heavy metals in the liquid, Atwater added. Often a wider range of toxins can be found in domestic sewage than in leachate, he said.
"Usually if the plant can treat domestic waste well, then it can treat leachate well," Atwater said.
