Erin Town Councillors still want to explore alternative technologies
for Erin’s future wastewater system, but discharging treated effluent into the
ground instead of the river will not be one of them.
They received a detailed technical report last week by engineer Gary
Scott of Ainley Associates that says a subsurface disposal system would be
impractical, risky and more costly than surface disposal. The analysis is
backed up by Credit Valley Conservation and the Ministry of the Environment and
Climate Change.
“It’s not competitive with surface water disposal and doesn’t give
any cost advantage,” said Scott. Council authorized the investigation last
year.
“The Master Plan had mentioned it, but subsurface disposal hadn’t
been looked at in detail, so we have plugged that hole.”
This will avoid the possibility that the overall study could be
challenged and delayed for failing to have studied sufficient options.
The projections are based on the possibility of “full build-out”,
meaning that homes could be built over a 20-30 year period on all of the lands
within the urban areas of Hillsburgh and Erin village that are already
designated for that use in the Official Plan.
Current homes in Erin village would generate wastewater of 2,244
cubic metres per day (m3/d), but that could more than double to
4,767 m3/d. The Hillsburgh flow could quadruple, from 600 to 2,400 m3/d.
For a subsurface discharge bed, Erin village would need 40 hectares
(98 acres), set back at least 300 metres from any creek or wetland. Such lands
do not exist near Erin village, even if they could be purchased.
“The MOECC would likely require a spare bed,” said Scott. “There is
a history of failure for subsurface systems in North America and Europe. The
ministry is cautious in approving them.”
Hillsburgh would require a 19.5 hectare (48 acre) lot, which Scott
say may be possible. But he said the costs of building and maintaining
subsurface disposal in Hillsburgh, plus traditional river disposal in Erin
village, are 10-20 per cent higher than pumping Hillsburgh sewage to a single
treatment plant in Erin village.
Preliminary estimates (at full build-out) show the cost of treating
waste at two separate areas at $71 million, compared to $61.7 million at a
single Erin village site. That does not include the huge separate cost of
building the collection pipe system throughout the villages.
Previously, new growth was expected to be limited to 6,000
residents. But a strategy suggested last year (but not yet approved by council)
could see well over 10,000 new residents. Some existing neighbourhoods could be
exempt from having sewers, and intensive treatment of sewage could allow for
more effluent being allowed in the river.
Full details of the strategy are to be presented
at a Public Information Centre (PIC). This has been delayed, and is expected
this spring. The current phase of the Environmental Assessment is intended to
research various practical options for collection and treatment of wastewater.