Karst Limestone
"Filthy water cannot be washed." African Proverb
Graphic of Water flow
through Karst Limestone
Unstable soils and bedrock
The Ontario Ministry of Natural Resources warns against development where soil and bedrock instability occurs : "Unstable soils and bedrock are naturally occurring hazards that pose a threat to life and property. As a result, property or lands could be unsafe for development and site alteration. "
Hazards:
"Unstable soils and bedrock can become hazardous from the impacts of heavy rainfall or geological processes (earth tremors, freeze-thaw soil action), human modification, or combination of all the above.
Karst is included as an unstable bedrock site:
Karst formations are areas where water flowing over and through limestone and dolomite bedrock deposits creates sinkholes, trenches and underground caverns.
Well data from Ontario Ministry of the Environment
"The map with pushpins shows drilled wells only. No dug well and no rain-fed cisterns are included so it represents the minimum number of wells in the area. While the locations are not exact, they indicate the presence of a registered well.
Groundwater Contamination
The Ministry of Natural Resources Emergency Management is responsible for when it comes to this type of bedrock: Water flowing over and through this type of rock can create sinkholes, trenches and underground caves and makes groundwater more susceptible to
contamination.
"In 2004, Ontario revised the Provincial Policy
Statement (PPS) to formally recognize the
unacceptable health and safety risks associated with
development in areas subject to soil and bedrock
instability."
Document: Soil and Bedrock Instability: What you need to know
We can clearly see in the plan amendment request, the water courses that run through the property in question and into the South Nation river, flowing through many agricultural fields in the process.
From document Understanding Natural Hazards
"Karst formation character and size depends on how acidic surface water is, the rate at which the rock dissolves, number of fractures and fissures in the rock, distance the water will percolate from surface to water table and the presence of impermeable layers above or below the limestone/dolomite layers."(section 8.3)
Groundwater contamination: a global issue
Groundwater contamination is a big issue across much of the world.
The Kentucky Geological Survey did extensive study on Karst Groundwater and recommends limiting industry over this terrain:
- Reasons for Karst Groundwater Vulnerability
- Recharge to karst aquifers bypasses the filtering capability of soil through macropores and swallow holes
- Groundwater flows through conduits so that there is little opportunity for filtration or sorption of contaminants onto aquifer material
- The movement of pollutants cannot be directly observed as in a surface-flowing stream
- Flow paths may take routes that are not apparent from the topography or slope of the land
- Flow velocities in karst aquifers are fast compared to velocities in granular aquifers, allowing little time to warn downstream users following a reported spill
- Flow is in converging conduits; therefore pollutants are not diluted through dispersal
- How to Protect Karst Groundwater
The best way to protect a karst aquifer from pollution is for humans to limit industry and other activity over the groundwater basin.