PEI Group fractured bedrock aquifer

Hydrogeological Context

Version	Metadata
	f64ad8c6-548f-4f2a-927d-a28f36a47c67

Project
Carboniferous Basin

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PEI Group fractured bedrock aquifer unit description

Update:2014-02-05

Physiography
In ascending order, the geological groups are: basement complex and Horton, Windsor, Mabou, Cumberland, Pictou and Prince Edward Island (PEI) Groups. The internal stratigraphy of these units is complex and often laterally discontinuous. The PEI group is composed of conglomerate, wackle, red sandstone and mudstone. It is covered with a sandy matrix till unit. This till feature involves high hydraulic conductivity, suggesting a good percolation of surface water. Considering that the hydrogeological unit also has a good hydraulic conductivity, the recharge rates are one of the most important in the region. The unit also shows one of the most important aquifer potential of the area. Groundwater flows in the rock through fractures and interconnected pores between grains. Since the fractures have a much higher permeability than the surrounding matrix, the water flows essentially in the fractures. Groundwater mainly follows the surface topography, flowing into the Northumberland Strait. Considering the weak protection provided by the till, the aquifer is vulnerable to contamination from surface. The groundwater quality is good, but there are some aesthetic problems of iron, manganese, nitrate and lead.
Hydrogeological region	Maritime Bassin
Hydrogeological context
Relief	The PEI group topography is flat and low altitudes. These are 0-50 m near the Northumberland Strait. They increase slightly in the western section to 50-100 m. The land includes a few gentle (2-5%) and moderate (10-15%) slopes along the river.
Area	1562.00 km2
Lithology
Description	In ascending order, the geological groups are: bedrock complex and Horton, Windsor, Mabou, Cumberland, Pictou and Prince Edward Island (PEI) Groups. The internal stratigraphy of these units is complex and often laterally discontinuous. The Horton Group consists of a sequence of sedimentary and volcanic rocks that is overlain by the marine limestone and evaporates strata of the Windsor Group. The marine beds are overlain by thick assemblages of continental origin, which correspond to the Riversdale-Mabou, Cumberland and Pictou groups. The PEI group is composed of conglomerate, wackle, red sandstone and mudstone. It is covered with a sandy matrix till unit. Some parts are covered with marine beaches.
Source
Aquifer
Aquifers	List of aquifers Prince Edward Island rock aquifer

Unit properties

Bedrock aquifer media


Typical value:	porous - fractured
Description	Groundwater circulates within the rock through fractures and interconnected pore spaces between the individual grains. Since fractures have a much higher permeability than the matrix around them, groundwater flows predominantly through fractures.
Source	Hydrogeological Atlas of South-Central Area of the Maritimes Carboniferous Basin

Confinement

Typical value:	semi confined - unconfined
Description	The system can be considered semi-confined, but confined and unconfined conditions can be found, mainly depending on the till layer composition. Considering the till unit is sandy, the confinement is less important for this hydrogeological unit than for the others.
Source	Hydrogeological Atlas of South-Central Area of the Maritimes Carboniferous Basin

Surficial sediment thickness
4 m Range: [0 to 8] m
Description	In PEI, the till thickness varies 0-8 m.
Source	Hydrogeological Atlas of South-Central Area of the Maritimes Carboniferous Basin

Well depth
68 m Range: [0 to 680] m
Source	Hydrogeological Atlas of South-Central Area of the Maritimes Carboniferous Basin

Groundwater depth
8.65 m Range: [0 to 48.8] m
Source	Hydrogeological Atlas of South-Central Area of the Maritimes Carboniferous Basin

Surficial unit hydraulic conductivity
0.0000013 m/s
Description	PEI is one of the groups exhibiting the largest hydraulic conductivity values.
Source	Hydrogeological Atlas of South-Central Area of the Maritimes Carboniferous Basin

Bedrock hydraulic conductivity
Range: [1e-06 to ] m/s
Description	The hydraulic conductivity varies between above 1E-6 m/s and below à 5E-5 m/s and above 5E-5 m/s
Source	Hydrogeological Atlas of South-Central Area of the Maritimes Carboniferous Basin

Regional precipitation
1047 mm/y Range: [916 to 1105] mm/y

Regional evapotranspiration
Range: [345 to 440] mm/y
Source	Hydrogeological Atlas of South-Central Area of the Maritimes Carboniferous Basin

Regional recharge
300 mm/y
Description	The recharge rates are the second most important in the area.
Source	Hydrogeological Atlas of South-Central Area of the Maritimes Carboniferous Basin

Regional discharge

Description	The Northumberland Strait is a discharge for the PEI unit.
Source	Hydrogeological Atlas of South-Central Area of the Maritimes Carboniferous Basin

Hydrogeological unit potential

Typical value:	Good or variable aquifer
Description	This unit has one of the best aquifer potential in the area.
Source	Hydrogeological Atlas of South-Central Area of the Maritimes Carboniferous Basin

Aquifer vulnerability

Typical value:	High

Groundwater Quality

Description	Groundwater quality is good, but has some aesthetic problems of iron, manganese, nitrate and lead.
Source	Hydrogeological Atlas of South-Central Area of the Maritimes Carboniferous Basin