Earth Sciences Report 1969-01

Earth Sciences Report 1969-01

ESR 1969-01

Groundwater Chemistry and Hydrology of the Handhills Lake Area, Alberta

Author(s) Vandenberg, A. Lennox, D.H. Date 1969-01-01

This report describes the groundwater chemistry and hydrology in an area of 275 square miles between the crest of the Hand Hills and Bullpound Creek and attempts to correlate chemical properties of the groundwater with position in the flow system and chemical nature of the sedimentary rocks.

The bedrock formations found at or near the surface in the study area are the Bearpaw and Edmonton Formations of late Cretaceous age, and the Paskapoo and later beds of Tertiary age. The Bearpaw Formation, a relatively impermeable marine shale, completely underlies the area and is considered to form a very effective, although not necessarily complete, barrier to the downward movement of meteoric water. The Edmonton Formation, a series of alternating lenticular beds of argillaceous sandstone, shale, and coal which immediately overlies the Bearpaw Formation, is found throughout most of the area and forms the greater part of the framework through which groundwater moves from its recharge area in the Hand Hills toward the discharge area in the lowlands surrounding Bullpound Creek. The permeability of this formation is generally extremely low because of the high clay content but the coal beds are sufficiently permeable to supply local farm needs. Most farm wells in the study area pump water from these beds but yields are commonly less than 5 gallons per minute.

The Tertiary strata are restricted to the elevated regions of the Hand Hills. The Paskapoo Formation commonly resembles the Edmonton Formation but is locally developed as thick sandstone beds of better permeability. Locally overlying the Paskapoo Formation are beds of marl, gravel, sand, and conglomerate.

The surficial deposits are varied in nature but are primarily of glacial or glaciofluvial origin. The buried gravels of the preglacial Hanna channel and the lake and outwash sands to the south of Watts and Hanna have above average permeabilities and hence have some hydrologic significance as well as some water supply potential. An aquifer test for the channel gravels resulted in an estimated single well safe yield of 60 imperial gallons per minute; the lake and outwash sands have reported yields which are much lower but these deposits have significance because meteoric water can infiltrate them readily.

Hydrologically, the study area can be subdivided into four parts: 1)a high-level recharge area in the elevated region of the Hand Hills, 2)an area of active discharge through springs and seepages forming a bond along the steep northern and western flanks of the Hand Hills, 3)a lowland area of hidden discharge through evapotranspiration, and 4)a lowland recharge area south of the town of Hanna where the presence of near-surface permeable deposits facilitates infiltration of precipitation.

Water-level measurements and calculated vertical components of the hydraulic gradient revealed: 1)a strong horizontal component of flow in the Paskapoo sandstones, 2)a distortion in the regional flow system in the lowland area, possibly caused by the Hanna channel deflecting groundwater flow in its vicinity, and 3)near stagnant or essentially horizontal flow conditions in the lowland area north of the Hand Hills.

Chemically the groundwater ranges from hard bicarbonate water with less than 500 parts per million total dissolved solids in the Hand Hills to soft sulfate water with more than 3,000 parts per million total dissolved solids in the low area surrounding Bullpound Creek. Maps of the concentration of total anions and of selected ratios of various dissolved constituents illustrate the two basic types of areal variation in groundwater composition: (1) those due to simple aging of the groundwater as it moves through the subsurface and (2) those due to inhomogeneities in the flow medium. Maps illustrating the first type are characterized by lines of equal concentration which tend to be oriented transversely to the directions of groundwater flow; those illustrating the second type are characterized by lines of equal concentration which tend to be oriented along the directions of groundwater flow. To the first type belong the total solids, percentage sodium, and the percentage bicarbonate plus carbonate in those areas where sulfate reduction is not a factor. The calcium:magnesium ratio is the outstanding example of the second type from the present study but attempts to correlate the calcium:magnesium ratio map with measured calcium and magnesium contents for various formation samples met with only partial success. The percentage chloride and chloride:sulfate ratio show areal variations of both types. Except for the presence of the lowland recharge area, interpretation of the hydrologic and chemical data strongly favours the classical picture of recharge in the uplands and discharge in the lowlands.

Vanden Berg, A. and Lennox, D.H. (1969): Groundwater chemistry and hydrology of the Handhills Lake area, Alberta; Research Council of Alberta, RCA/AGS Earth Sciences Report 1969-01, 68 p.