U.S. Geological Survey Toxic Substances Hydrology Program--Proceedings of
the Technical Meeting Charleston South Carolina March 8-12, 1999--Volume 3
of 3--Subsurface Contamination From Point Sources, Water-Resources
Investigations Report 99-4018C
Effects of Lithology and Fracture Characteristics on Hydraulic Properties
in Crystalline Rock: Mirror Lake Research Site, Grafton County, New Hampshire
By Carole D. Johnson
ABSTRACT
A combination of subsurface borehole imaging data and drilling logs were used
to characterize the fractures and lithology in 40 bedrock wells at the fractured-rock
research site in the Mirror Lake area in Grafton County, New Hampshire. The
purpose of the research was to determine whether subsurface lithology and fractures
have an effect on the hydraulic conductivity of the crystalline-rock aquifer
in the Mirror Lake area. The distribution of fractures and lithology was quantified
with respect to depth, altitude, topographic setting, and spatial distribution.
The density of fracturing was described and comparisons were made between lithology,
fracture characteristics, and hydraulic-conductivity measurements. Fracturing
was found to be related to lithology, depth, and topographic setting. No clear
correlation was established between hydraulic conductivity and fracture properties
including alteration, oxidation, aperture, orientation, and density.
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