Minutes
February 11, 1999
University of Idaho - McClure Hall # 304
Calvin C. Warnick Hydrogeological Library
Craig Benjamin (WSU),
Steve Gill (Executive Secretary), Sue Hinz (Pullman), Don Huskey (UI), Derek
Pohle (Whitman County), Larry Kirkland, Vice Chair. (UI), Gary Presol (Moscow),
Tom Townsend, Chair. (Latah County), Mark Workman (Pullman).
Jay Becker (WSU), Pam
Palmer (Moscow), Loreca J. Stauber (Latah County), Les Wigen (Whitman County).
Kent R. Johnson,
Ph.D., P.G. (Aquila Geosciences, Inc.), Ron Cooper (Pullman), Debbie Ellard
(City of Moscow, Conservation Officer), Bob Haynes (Idaho Department of Water
Resources), Tom Lamar (PCEI), Kathleen Warnick.
The meeting was
called to order by PBAC Chairman Tom Townsend at 8:43 a.m.
Minutes from the November 12, 1998 and January 14, 1999
meeting were unanimously approved (D. Huskey motioned, M. Workman seconded).
Problems
arise when
contrasts in geologic materials are very similar and interpretation of the data
is vague and possible subject to each individual geophysicist opinion. There are several geophysics techniques that
could be employed to find the shape of the Palouse ground water basin; however,
some of the techniques would not work well due to the amount of ambiguity in
the method.
Seismic
Geophysics:
the problem with this method is that the basalt and underlying basement rock
are too similar in their density.
Magnetic
Geophysics: this
method might give false data due to the magnetic properties within basalt.
Gravity Geophysics: this method could be employed with good results. Gravity geophysics looks at the density contrasts between rocks. Problems might arise in the interpretation of the data 1) without accurate elevation information, 2) in areas next to hills versus valley floor, and 3) dependant on the thickness and composition of interbeds between the basalt flows.
Time-delay
Electromagnetic Geophysics: this method uses a pulsing electric current below transmitter wire
that is a very accurate on the ground method but, it is extremely time
consuming for a basin-wide survey.
Magnetotelluric Geophysics: this method uses natural currents within the Earth and measures these currents over time using real-time data. A common problem with magnetotelluric is aliasing – which is best described as the effect you get when watching the wheels of a stagecoach in a movie and the wheels appear to be going in backwards. By not sampling frequently enough the data will be false. Setting each measuring station close enough to prevent aliasing can reduce this problem. Advantages of magnetotellurics include 1) since it is uses real-time data results can be collected, interpreted and presented usually within 24 hours, 2) magnetotellurics can be interfaced with Gravity geophysical data, and 3) it is a very cost-effective method.
D. Pohle asked whether an aerial gravity
geophysics survey might work better?
Mr.
Johnson replied
that there might be a problem with the resolution of the data.
What is
the cost
of the different geophysics methods asked G.
Presol?
Mr.
Johnson replied
that Gravity geophysics will usually run between $50 and $60 per station;
however, the stations would need to be on the order of 1000 feet apart across
the basin. Commercially, this would be
a very expensive survey,
The cost of magnetotellurics is variable and can run
between $125 and $1,250 per station.
Karen Kristofferson, a geophysicist out of Colorado, places the cost for
a study at $350 to $450 per station with a mobilization/demobilization cost for
the geophysics crew of about $7,500.
If the crew ran a survey of similar scope to the Klein and others (1987)
study done for the USGS model (Lum and others, 1990) the cost would be:
[40 stations x $450 + Mob/Demob
$7,500 = $25,000 to $30,000]
Reprocessing
of Existing Data: Mr. Johnson notes that today’s technology has improved substantially
from that of the mid-1980’s. He
suggests that the first step the PBAC might employ is to reprocess and
reinterpret the existing data set from the Klein and others (1987) study.
S. Gill stated that there is a substantial amount of
geophysical data that was collected from the 1960’s through the early-1980’s by
Dr, Crosby, WSU. Dr. Crosby used
down-hole geophysics on many private rural wells on the Palouse. His untimely death resulted in the data
never being processed or interpreted.
His office, on the WSU campus, still has the unprocessed data. This existing data could be used in
conjunction with the Klein and others (1987) to gain a better understanding of
the shape of the basin.
Project
Management:
Mr. Johnson pointed out that before any project is undertaken that the project
management must be in order. If the
PBAC wants to use the data to direct their future management decisions it will
require full-time management of the data including 1) proper data collection,
2) timely incorporation of that data into the model, and 3) aggressive analysis
of the model to base future management decisions.
Tom Townsend, on behalf of the PBAC, thanked Mr.
Johnson for his time and unique insight.
PBAC
Aquifer Recharge Subcommittee:
L. Kirkland stated that he has been in
contact with both Representative Trail and Dr. Christian Petrich, IWWRI,
concerning the revision of artificial recharge language for the State of
Idaho. S. Gill offered to follow-up and
contact Dr. Petrich for an update on the progress.
PBAC
Personnel Discussion: Hydrologic Technician, Conservation Coordinator, and
Executive Secretary: T. Townsend organized
a subcommittee to decide on the future PBAC personnel. Members include: C. Benjamin, S. Hinz, G.
Presol, T. Townsend, and M. Workman.
The subcommittee will report at the March PBAC meeting.
New Water
Conservation Coordinator for the City of Moscow: G. Presol introduce Debbie Ellard, a long-time employee of
the City of Moscow Water Treatment Facility, as the new Water Conservation
Coordinator for the City of Moscow.
Debbie will be promoting water conservation education in schools and
public outreach.
The meeting was adjourned at approximately 11:15 A.M.
8:00 am Wednesday
March 31, 1999
University of Idaho McClure
Hall # 304
Respectfully
Submitted,
Steve W. Gill, PBAC Executive Secretary/Technical Advisor