Sedimentary rocks overlain by till

Hydrogeological Context

Version	Metadata
	0ea68738-1bd5-4755-9ed6-ce341fd5f47c

Project
Portneuf

Update:2014-01-29

Physiography
The sedimentary rocks include limestones of Trenton Group and shales of Utica Group. These are highly fractured rocks, very friable in the case of shales, and affected by the dissolution process that led to an early karstification in limestone of St. Casimir and Pont-Rouge. The rocks are covered by a continuous till unit. Depending on the extent and thickness of till that overcomes the aquifer, the water table conditions are highly variable. It is the same for the vulnerability of the aquifer, which is also function of the till deposits characteristics. Groundwater flows through fractures and voids in the rock. The aquifer potential is good and the water of calcic bicarbonate type show low mineralization.
Hydrogeological region	St. Lawrence Platform
Hydrogeological context
Relief	The sedimentary rocks have a flat terrain. They are located along the St. Lawrence River. The sedimentary rocks altitudes are among the lowest observed in the region.
Area	157.00 km2
Lithology
Description	The Paleozoic rocks of the sedimentary platform are mainly composed of limestones of Trenton Group and shales of Utica Group. The regional dip of these rocks is 1 ° to 2 ° to the south. These are highly fractured rocks, very friable in the case of shales, and affected by the dissolution process that led to an early karstification in limestone of St. Casimir and Pont-Rouge. The rock formations are covered by a continuous till unit.
Source
Aquifer
Aquifers	List of aquifers Sedimentary rock aquifer

Bedrock aquifer media


Typical value:	karst - fractured
Description	The Paleozoic rocks of the sedimentary platform are mainly composed of limestones of the Trenton Group and shales of Utica Group. The limestones of St-Casimir, St-Marc-des-Carrières and Pont-Rouge sectors show a beginning of karstification.

Confinement

Typical value:	semi confined - unconfined
Description	Conditions of water table in these aquifers can be highly variable, depending on the extent and thickness till deposits which surmount.

Well depth
24.4 m Range: [0.7 to 145.4] m

Groundwater depth
0 m Range: [0 to 2.88] m

Surficial unit hydraulic conductivity
9E-7 m/s
Description	The till unit has a mean hydraulic conductivity of 9,0E-7 m/s.
Methode	Hazen formula, based on 10 samples

Regional precipitation
1121.5 mm/y Range: [1063.1 to 1168.2] mm/y
Methode	Precipitation data are from Environment Canada. The value represents the average of the climate normals (1981-2010) measured on the stations distributed in or near the hydrogeological unit. The stations were selected so the average precipitation is as representative as possible of the whole hydrogeological unit.

Hydrogeological unit potential


Aquifer vulnerability
3 Range: [0 to 5]

Groundwater Quality

Description	The water type is calcic bicarbonate, showing a low mineralization.