Open AccessImpact of blasting on groundwater composition in a fracture in Canada's Underground Research Laboratory
Author(s) -
Gascoyne Mel,
Thomas David A.
Publication year - 1997
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/96jb02857
Subject(s) - groundwater , aquifer , geology , fracture (geology) , hydrology (agriculture) , hydraulic conductivity , geochemistry , soil science , geotechnical engineering , soil water
Groundwater composition in a discrete, water‐bearing fracture in granitic rock at the Underground Research Laboratory, Manitoba, was monitored during a period of underground excavation of adjacent rock to determine the impact of conventional blasting techniques and rock fracturing on the concentration of dissolved constituents. This work has relevance to the study of hydrogeochemical anomalies associated with seismic activity. Short‐lived anomalies such as decreases in dissolved anion (Cl, F, Br, SO 4 ) and gas (He, Rn) concentrations and concurrent increases in NO 3 and O 2 concentrations were seen shortly after two blasts located opposite the groundwater sampling site. A third blast downstream of the site resulted in variability in dissolved gases concentrations but showed no impact on dissolved anion concentrations. The results are compared with various models used to account for hydrogeochemical fluctuations associated with earthquakes. The data best fit a general form of the aquifer breaching/fluid mixing model in which hydrochemical responses are caused by localized changes in hydraulic conductivity along the plane of a fracture which, in turn, cause changes in mixing ratio of groundwater at the monitoring site.