Geology and properties of limestone

Geology

Short description of the geology... A good introduction in Danish is given in the Report .

Properties of limestone

Borehole cores from the Akacievej field site.

Limestone geologies can be heavily fractured and include almost impermeable chert layers and nodules. Flow predominantly occurs in the fractures due to a much higher hydraulic conductivity as in the limestone matrix. The limestone found at the Akacievej site is a carbonated sand limestone (Copenhagen chalk) and a bryozoan limestone, both with a strongly varying hardness. Due to glacial activity, the uppermost 1-5 meters of the limestone are crushed.

The sorption behavior for chlorinated solvents on limestone was examined in Salzer (2013). For chlorinated solvents like PCE, sorption to limestone can be strong (kd values of 0.5-1 L/kg were observed).

Typical values of the hydraulic properties and the transport properties at the Akacievej field site

The following table gives an overview of values that were determined for the Akacievej site:

Parameter	Value	Comment
K_crushed	5x10^-4 m/s	crushed limestone conductivity
n_matrix	0.10 - 0.20	matrix porosity
ap	2 mm	typical fracture aperture
K_matrix	1x10^-7 m/s	limestone conductivity
B	20 - 25 m	aquifer thickness
D_m	7.5x10^-7 m^2/s	effective diffusivity
k_d	0.5-1.0 L/kg	sorption coefficient for PCE on limestone

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