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| Publications— Scientific Investigations Reports |
In cooperation with the U.S. Environmental Protection Agency
U.S. Geological Survey Scientific Investigations Report 2006-5014
By Philip H. Bird
This report is available online in Portable Document Format (PDF). If you do not have the Adobe Acrobat PDF Reader, it is available for free download from Adobe Systems Incorporated.
View the full report in PDF 15.0 MB
Borehole geophysical logging and aquifer-isolation (packer) tests were conducted in well MG-1693 (NP-87) at the North Penn
Area 5 Superfund Site near Colmar, Montgomery County, Pa. Objectives of the study were to identify the depth and yield of
water-bearing zones, occurrence of vertical borehole flow, and effects of pumping on water levels in nearby wells.
Caliper, natural-gamma, single-point-resistance, fluid-temperature, fluid-resistivity, heatpulse-flowmeter, and
borehole-video logs were collected. Vertical borehole-fluid movement direction and rate were measured under nonpumping conditions.
The suite of logs was used to locate water-bearing fractures, determine zones of vertical borehole-fluid movement, and
select depths to set packers. Aquifer-isolation tests were conducted to sample discrete intervals and to determine specific
capacities of water-bearing zones and effects of pumping individual zones on water levels in two nearby monitor wells.
Specific capacities of isolated zones during aquifer-isolation tests ranged from 0.03 to 3.09 (gal/min)/ft (gallons per
minute per foot). Fractures identified by borehole geophysical methods as water-producing or water-receiving zones produced
water when isolated and pumped.
Water enters the borehole primarily through high-angle fractures at 416 to 435 ft bls (feet below land surface) and 129
to 136 ft bls. Water exits the borehole through a high-angle fracture at 104 to 107 ft bls, a broken casing joint at 82 ft
bls, and sometimes as artesian flow through the top of the well. Thirteen intervals were selected for aquifer-isolation
testing, using a straddle-packer assembly. The specific capacity of interval 1 was 2.09 (gal/min)/ft. The specific
capacities of intervals 2, 3, and 4 were similar—0.27, 0.30, and 0.29 (gal/min)/ft,respectively. The specific capacities
of intervals 5, 6, 7, 8, and 10 were similar—0.03, 0.04, 0.09, 0.09, and 0.04 (gal/min)/ft,respectively. Intervals 9, 11,
and 12 each showed a strong hydraulic connection outside the borehole with intervals above and below the isolated interval.
The specific capacities of intervals 9, 11, 12, and 13 were similar—2.12, 2.17, 3.09, and 3.08 (gal/min)/ft, respectively.
The aquifer-isolation tests indicate that wells MG-1693 (NP-87) and MG-924 (NP-21) are connected primarily through
the high-angle fracture from 416 to 435 ft bls. Pumping in either of these wells directly impacts the other well, allowing
the pumped well to draw from water-bearing zones in the non-pumped well that are not present in or are not connected
directly to the pumped well. The two boreholes act as a single, U-shaped well. The aquifer-isolation tests also show that
the lower zones in well MG-1693 (NP-87) are a major source of hydraulic head in well MG-1661 (W-13) through the broken
casing joint at 82 ft bls. Water moving upward from the lower intervals in well MG-1693 (NP-87) exits the borehole through
the broken casing joint, moves upward outside the borehole, possibly around and (or) through a poor or damaged casing seal,
and through the weathered zone above bedrock to well MG-1661 (W-13).
Samples for volatile organic compounds (VOCs) were collected in nine isolated intervals. Six compounds were detected
(1,1-dichloroethane, 1,1-dichloroethene, cis-1,2-dichloroethene, toluene, 1,1,1-trichloroethane, and trichloroethene
(TCE)), and TCE was found in all nine isolated intervals. Intervals 4 (124-149 ft bls) and 6 (277-302 ft bls) had the
highest total concentration of VOCs (6.66 and 6.2 micrograms per liter, respectively). Intervals 1 (68-93 ft bls) and
4 each had five compounds detected, which was the highest number of compounds detected. Interval 5 (252-277 ft bls) had
the lowest total concentration of VOCs (0.08 microgram per liter) and the least number of VOCs detected (one). Detected
compounds were not evenly distributed throughout the intervals. Contaminants were found in shallow, intermediate, and
deep intervals and were associated with high-angle fractures and rough areas that showed no distinct fractures.
Abstract
Introduction
Purpose and Scope
Geohydrologic Setting
Brunswick and Lockatong Formations
Ground-Water-Flow System
Previous Investigations
Well-Numbering System
Methods of Investigations
Borehole Geophysical Logs
Borehole Video Logs
Heatpulse Flowmeter
Aquifer-Isolation Tests
Results of Borehole Geophysical Logging
Results of Aquifer-Isolation Tests
Interval 1 (68-93 Feet Below Land Surface)
Interval 2 (87-112 Feet Below Land Surface)
Interval 3 (99-124 Feet Below Land Surface)
Interval 4 (124-149 Feet Below Land Surface)
Interval 5 (252-277 Feet Below Land Surface)
Interval 6 (277-302 Feet Below Land Surface)
Interval 7 (302-327 Feet Below Land Surface)
Interval 8 (339-364 Feet Below Land Surface)
Interval 9 (362-TD Feet Below Land Surface)
Interval 10 (382-407 Feet Below Land Surface)
Interval 11 (412-437 Feet Below Land Surface)
Interval 12 (436-TD Feet Below Land Surface)
Interval 13 (436-461 Feet Below Land Surface)
Distribution of Volatile Organic Compoundsand
Summary and Conclusions
Acknowledgments
References Cited
This report is available online in Portable Document Format (PDF). If you do not have the Adobe Acrobat PDF Reader, it is available for free download from Adobe Systems Incorporated.
View the full report in PDF 15.0 MB
For more information about USGS activities in Pennsylvania contact:
Director
USGS Pennsylvania Water Science Center
215 Limekiln Road
New Cumberland, Pennsylvania 17070
Telephone: (717) 730-6960
Fax: (717) 730-6997
or access the USGS Water Resources of Pennsylvania home page at:
http://pa.water.usgs.gov/.
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