Ground Water Flow and Transport in Fractured Rock: (Mirror Lake, New Hampshire)

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An areal view of Mirror Lake, which is located in the Hubbard Brook Experimental Forest, NH

Outcrop of a fractured rock aquifer where fracture characteristics were measured

Drilling a bedrock well in the Mirror Lake, NH, watershed. USGS scientists used bedrock wells to characterize bedrock geology and fractures, and to conduct hydraulic and tracer tests to identify properties of fractures that control fluid movement and chemical migration

USGS scientists positioning drill stems so equipment can be lowered into a bedrock well to conduct a tracer test in fractured rock. A series of tracer tests were conducted to identify interconnected fractures at the site

USGS scientists lowering equipment into a bedrock well to conduct a tracer test in fractured rock. Tracer tests were used to gather information on the hydraulic and solute transport properties of fractures and fracture networks

USGS scientists making a manual water-level measurement during a hydraulic test in a fractured-rock aquifer. Manual water-level measurements were used to check pressure transducers that automatically record water levels in wells

Collecting a water-quality sample from a bedrock well during a tracer test in a fractured-rock aquifer. Controlled tracer tests were conducted to identify processes that control the migration of contaminants in fractures

USGS scientist collecting a water sample during a tracer test in fractured rock. The tracer test was designed to study the diffusion of solutes from fractures into the primary porosity of the rock

USGS scientist examining rock chips from drilling a bedrock well. The rock chips were used to identify the subsurface lithology of the fractured-rock aquifer that the borehole passed through

Outcrop studies were conducted to assess the orientation, length, aperture, and other parameters of fractures in the Mirror Lake watershed. This information was used to better understand the connectivity of fractures and their capacity to transmit water

USGS scientists studied outcrops in the Mirror Lake, NH, watershed, such as this one from a road cut on Interstate 93, to characterize the fracture network in the study area. The pavement method was used, which involves mapping fracture traces on a detailed geologic map

USGS scientist collecting a ground-water sample for a study of the water chemistry of a fractured-rock aquifer

Mirror Lake, NH, located in the Hubbard Brook Experimental Forest, is the location of a research site where USGS scientists and others developed methods to characterize the ground-water flow and the transport of chemical constituents in fractured rock

Sealing a ground-water sample in a glass ampoule for the analysis of chlorofluorocarbons (CFCs). The concentration of CFCs in water can be used to date the age of ground water

A set of packers being lowered into a bedrock well. The straddle packer apparatus was used to test the hydraulic properties of individual fractures or closely spaced fractures in a borehole

Bedrock wells at the site have packers that isolate the most permeable sections from each other. This is a view of an equipment box mounted on top of a well casing. Float-counterweight equipment is connected to a digital data acquisition system that records the hydraulic head in each section of the well. In this well there are three sections that are connected to the surface with PVC pipes

A USGS scientist measuring the water level in a well with a steel tape to check the accuracy of automated measurements. Data from the data acquisition system were downloaded at the same time

USGS scientists used a suite of geophysical logs from bedrock wells, such as acoustic televiewer and heat-pulse flow meter logs, to assist with identifying rock types and permeabable fractures at the site

USGS scientist conducting a surface seismic study to determine the direction of fracturing at the site. A sledge hammer is being used as the seismic source for the line of geophones marked by the red flags