FEDERAL WATER POLLUTION CONTROL ADMINISTRATION
NORTHWEST REGION, PACIFIC NORTHWEST WATER LABORATORY
LIQUID WASTE DISPOSAL
IN THE
LAVA TERRANE OF CENTRAL
OREGON
U.S. DEPARTMENT OF THE INTERIOR
FEDERAL WATER POLLUTION CONTROL ADMINISTRATION
NORTHWEST REGION
APRIL 1968
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LIQUID WASTE DISPOSAL
IN THE
LAVA TERRANE OF CENTRAL OREGON
Prepared by
Jack E. Sceva
Technical Projects Branch
Report No. FR-4
U. S. Department of the Interior
Federal Water Pollution Control Administration
Northwest Region
Pacific Northwest Water Laboratory
Corvallis, Oregon
May 1968
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ABSTRACT
A large part of the Middle Deschutes Basin in Central
Oregon is underlain by basaltic lava flows that restrict the
construction of conventional drain fields for liquid waste
disposal. Drilled disposal wells in the lava serve as the
chief method of liquid waste disposal.
The disposal wells are concentrated in the Bend, Redmond,
and Madras areas. They range from a few feet to over 400 feet
in depth. Large quantities of ground water underlie these areas
and are being developed for domestic water supplies. The in-
jection of liquid waste into disposal wells and the construction
of deep uncased water wells create a threat to water quality.
The prevention of further drain well construction and the
casing of all deep water wells are recommended.
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TABLE OF CONTENTS
Page
I. INTRODUCTION
A. Initiation of Study 1
B. Purpose 1
C. Scope of Study 2
II. SUMMARY
A. Findings 5
B. Recommendations 6
III. DESCRIPTION OF STUDY AREA
A. Geologic Setting 9
B. Hydrology and Water Supply 12
C. Liquid Waste Disposal Practices ... 18
D. Well and Spring Numbering System ... 23
IV. BEND AREA
A. Geology and Occurrence of Ground Water. 27
B. Liquid Waste Disposal 30
C. Chemical Quality of Ground Water ... 36
V. REDMOND AREA
A. Geology and Occurrence of Ground Water 37
B. Liquid Waste Disposal 40
C. Chemical Quality of Ground Water ... 40
D. Springs in the Crooked and Deschutes
River Canyons 43
VI. MADRAS AREA
A. Geology and Occurrence of Ground Water 51
B. Liquid Waste Disposal 52
C. Chemical Quality of Ground Water ... 55
iii
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VII. DISCUSSION
A. Pollution Threat Caused by the Operation
of Disposal Wells 57
B. Methods of Reducing the Threat of Ground
Water Pollution 62
VIII. SELECTED REFERENCES 66
iv
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LIST OF FIGURES
No. Page
1 Map of Oregon Showing the Location of the
Deschutes River Basin and the Project Area . . 3
2A View of the Crooked River Canyon near Madras . 11
2B Wall of Crooked River Canyon Showing Lavas
in the Madras Formation 11
3 Major Rock Units in the Deschutes River
Basin 13
4 Map of the Project Area Showing Chief Area of
Ground Water Discharge 15
5 Monthly Mean August Flow for the Crooked
River Near Culver, Oregon 17
6 Diagram of a Typical Domestic Sewage Disposal
System in the Middle Deschutes Basin 19
7A Pit Being Excavated in Lava for Septic Tank. . 20
7B Septic Tank Installed in the Pit Shown in 7A . 20
8A Sewage Disposal Well Under Construction
at Bend 21
8B Opal Spring in the Crooked River Canyon ... 21
9A Farm Drain Well Under Construction Near
Redmond 24
9B Typical Farm Drain Well for the Disposal of
Field Runoff 24
10A Entrance to Horse Cave--A Lava Tube Located
Near Bend 28
10B Disposal Sump Utilized by the Bend Municipal
Sewer System for the Subsurface Disposal of
Sewage 28
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No.
Page
11 Block Diagram of the Bend Area Showing
Representative Wells and the Altitude of
Water Levels 31
12 Hourly Flow and Suspended Solids of the
Effluent from Bend's Municipal Sewer System. . 35
13 Block Diagram of the Redmond Area Showing
Representative Wells and the Altitude of
Water Levels 41
14 Block Diagram of the Madras Area Showing
Representative Wells and the Altitude of
Water Levels 53
15 Diagram Showing How an Uncased Water Well
Can Serve as a Conduit for the Movement of
Perched Water to the Regional Water Table. . . 60
LIST OF PLATES
1 Map of the Bend Area Showing the Location
of Wells In Pocket
2 Map of the Redmond Area Showing the Location
of Wells In Pocket
3 Location of Wells in the Madras Area In Pocket
VI
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LIST OF TABLES
Table No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Description of water wells in the Bend
area
Materials penetrated by wells in the
Chemical analysis of ground water in
Description of representative disposal
Description of water wells in the Redmond
Materials penetrated by wells in the
Chemical analysis of ground water in
Description of representative disposal
wells in the Redmond area
Description of water wells in the Madras
Materials penetrated by wells in the
Chemical analysis of ground water in
Description of representative disposal
Chemical analysis of water from springs
Chemical analysis of water from springs
in the Crooked and Deschutes River Canyons
Chemical analysis of sewage and liquid
Appendix
Appendix
Appendix
Appendix
Appendix
Appendix
Appendix
Appendix
Appendix
Appendix
Appendix
Appendix
Appendix
Appendix
Appendix
VIZ
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LIQUID WASTE DISPOSAL IN THE LAVA
TERRANE OF CENTRAL OREGON
I. INTRODUCTION
A. Initiation of Study
The Federal Water Pollution Control Act, as amended,
authorizes the Federal Water Pollution Control Administration
to conduct studies and surveys concerning problems of water
pollution that are confronting any State, interstate agency,
community, municipality, or industrial plant. Such studies
and surveys must be requested by a State water pollution con-
trol agency.
In January 1966, the Oregon State'Sanitary Authority
requested the Federal Water Pollution Control Administration
to investigate the "environmental hazards associated with the
disposal of sewage wastes in deep lava sinkholes in the Deschutes
Valley Oregon". The project was approved for study by the
Federal Water Pollution Control Administration, and work
commenced in June 1966.
B. Purpose
The study was planned to include an initial feasibility
study phase that was expected to last about one year. During
this phase, basic information about waste, waste disposal
practices, and the occurrence, chemical character, and movement
of ground water would be obtained for use in preparing a plan
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and cost estimate for a full-scale study of the problem. If
the full-scale study could be expected to provide sufficient
information to justify its cost, it would be staffed and con-
tinued.
The geologic, hydrologic, and water-quality information
gathered during the feasibility study indicated that ground-water
pollution was not yet a serious problem in the Middle Deschutes
Basin and that any full-scale study would be extremely expensive
as numerous deep test wells would be required. The information
gained in a full-scale investigation would be extremely helpful
in the development of the ground-water resources of the area,
but would not aid materially in eliminating the threat of water
pollution. It was, therefore, decided that further study would
not be undertaken at this time.
C. Scope of Study
1. Location of Study Area
The Deschutes River is a northward flowing stream that
drains a large part of the eastern slope of the Cascade Mountains
in Oregon. It is tributary to the Columbia River about 90 miles
east of Portland. Its drainage basin, which is the second largest
in the State, exceeds 10,000 square miles. The location is shown
on Figure 1.
The project area was confined to the west-central part
of the drainage basin. The population of the project area is
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DESCHUTES RIVER BASIN
PROJECT AREA
COLUMBIA RIVER
*SALEM
•ftCORVALLIS
FIGURE 1. --MAP OF OREGON SHOWING THE LOCATION OF
THE DESCHUTES RIVER BASIN AND THE PROJECT AREA
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about 25,000 and is concentrated in three towns. Bend (13,200),
Redmond (3,900), and Madras (1,800). These three towns served
as centers of concentrated study. The geology, occurrence of
ground water, and the waste disposal practices of each area are
described separately in this report.
2. Description of Study
The information collected during the feasibility study
was to aid in planning and to provide information useful in
determining sites, depths, and costs for test wells to monitor
ground-water quality. Information on many of the existing water
wells was collected to define the water table and subsurface
geology. Water samples were collected from numerous wells and
springs to provide information on the quality of water.
After it was decided that a full-scale investigation
would be too expensive, this report was prepared to provide the
basic data on the geology, ground water, and liquid waste disposal
operations in the Middle Deschutes Basin. The report also con-
tains some recommendations as to how to reduce the threat of ground-
water pollution. The basic data is given in a separate appendix.
3. Acknowledgments
The help and assistance of the Tri-County Health Depart-
ment, the City of Bend Engineering Department and the U. S. Forest
Service are gratefully acknowledged. The information contributed
by water well and disposal well contractors and well owners is also
appreciated.
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II. SUMMARY
A. Findings
The following are some of the general findings that relate
to the occurrence and movement of ground water and waste disposal
operations.
1. A large part of the study area is underlain with
porous and permeable lava flows that at most places extend from
land surface to depths of 50 to 100 feet.
2. The surficial lava flows are at most places under-
lain by layers of sand, gravel, pumice, and cinders.
3. The regional water table ranges from 500 to 600
feet below land surface at Bend, 250 to 300 feet at Redmond, and
300 to 400 feet at Madras. Some perched ground-water zones occur
in all three areas.
4. The ground-water resources of the study area con-
stitute the chief source of water supply still available for
development.
5. The regional water table in the Bend and Redmond
areas slopes generally northward, and ground water moves in that
direction.
6. A barrier of rocks having a low permeability tran-
sects the Deschutes River Basin near Madras. This barrier forces
all of the ground water to be discharged into the river system.
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Over one million acre-feet a year is discharged by springs in
the Crooked River Canyon north of Redmond.
7. Ground water from the regional water reservoir
is being developed from deep wells located throughout the study
area. Many of these are uncased wells, having only short sections
of surface casing.
8. Most of the ground water sampled in the study area
was of good chemical quality.
9. The chief method of sewage disposal in Bend, Redmond,
and Madras is by the discharge of septic tank effluent down
drilled disposal wells.
10. Most of the disposal wells in Bend and Redmond are
relatively shallow, and they discharge waste into cracks and
joints in the surficial lava flows.
11. Disposal wells in Madras are generally deeper than
those at Bend and Redmond, and they discharge waste into a lava
interbed in the Madras Formation.
12. The liquid wastes in the study area are chiefly
domestic wastes from individual septic tanks. There are no large
quantities of industrial waste being discharged to the ground at
this time.
B. Re commend aj: i on s
1. As more and more deep water wells are being con-
structed in the Middle Deschutes Basin and as more and more waste
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7
is being discharged to the ground each year, all deep water
wells should be adequately cased and pressure grouted so that
they will not provide avenues for pollutants to enter the regional
ground-water reservoir.
2. As it will be only a matter of time before the
continued and uncontrolled discharge of waste into disposal wells
will create a ground-water pollution problem, the further con-
struction of disposal wells should be discontinued.
3. The abandonment and plugging of existing disposal
wells should be encouraged. This can be best accomplished by
promoting the construction of municipal sewers and sewage treat-
ment plants at Bend, Redmond, and Madras.-
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III. DESCRIPTION OF STUDY AREA
A. Geologic Setting
The Bend-Redmond area is a broad, flat plain lying between
the Cascade Mountains on the west and the Ochoco Mountains on
the east. This plain is dissected by the deep canyons of the
Deschutes, Crooked, and Metolius Rivers. The elevation at Bend
is approximately 3600 feet above sea level; Redmond is 3000 feet
and Madras is 2200 feet.
This broad plain is mantled by extensive basaltic lava flows.
These flows are commonly referred to as the "rimrock lavas" as
s
they form the cliffs that border most of the canyons in the area.
The rimrock lavas serve as the chief rock unit for the disposal
of liquid waste in the Bend-Redmond area and range from about 50
to 150 feet in thickness.
The rimrock flows generally overlie a formation which is
composed chiefly of layers of pumice, ash, conglomerate, sandstone,
mudflow deposits, and contains some interbedded lava flows. This
formation, which has been named the Madras Formation, is the
primary source of ground water in the Middle Deschutes Basin.
In the Deschutes River Canyon north of Redmond, the Madras Forma-
tion exceeds 700 feet in thickness with its base unexposed.
At some places, the Madras Formation overlies the Columbia
River Basalt Formation. This formation is a series of basaltic
lava flows that underlies thousands of square miles in Oregon and
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10
Washington and serves as an Important source of ground water.
The areal extent of the Columbia River Basalt in the Middle
Deschutes Basin is not known, but it does crop out in the Crooked
River Canyon near Trail Crossing north of Redmond. Both the
Madras Formation and the Columbia River Basalt overlie the John
Day Formation. The John Day Formation is a sedimentary unit
composed chiefly of tuff. It has a low permeability and generally
does not transmit ground water.
After the deposition of the Madras Formation and the rimrock
lavas, a period of erosion resulted in the cutting of deep canyons
by the Deschutes, Crooked, and Metolius Rivers in the area north
of Redmond. This period of canyon-cutting was followed by another
period of volcanic activity. A tremendous volume of very fluid
basaltic lava originating southeast of Bend flowed northward and
spilled into the Crooked River Canyon. This lava, which has been
called the "intracanyon basalt" flowed downstream for more than
thirty miles and accumulated to depths of over 400 feet. A similar
but smaller accumulation of basalt also partially filled the
Deschutes River Canyon northwest of Redmond. During Recent time,
the Crooked and Deschutes Rivers eroded new canyons into the intra-
canyon basalt as terraces (Figure 2).
The John Day Formation transects the Deschutes River Basin
near Madras and forms a subsurface barrier that prevents the down-
stream movement of ground water. This barrier forces all of the
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11
FIGURE 2
A. VIEW OF THE CROOKED RIVER CANYON NEAR MADRAS.
INTRACANYON BASALT FORMS THE BROAD TERRACE.
B. WALL OF CROOKED RIVER CANYON SHOWING LAVAS IN THE
MADRAS FORMATION. INTRACANYON BASALT SHOWN AT
RIGHT.
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12
ground water to discharge into the river system where it con-
tinues its journey to the Columbia River in the flow of the
Deschutes River. Figure 3 is a diagrammatic section showing the
various rock units in the Middle Deschutes Basin and their water-
bearing properties.
B. Hydrology and Water Supply
The Upper Deschutes River south of Bend is a slow, meander-
ing stream that winds its way across an old lake bed which formed
when the ancestral Deschutes River was impounded by lava flows
originating at Lava Butte. These flows blocked the course of
the Deschutes River and forced it to erode a new channel across
a ridge of volcanic rock. This new channel is now a series of
falls and rapids that have been named Benhara Falls. A large
amount of ground water discharges into the Deschutes River up-
stream from Benham Falls, but a well recently constructed by the
U. S. Forest Service at Lava Butte, a few miles to the east, has
a static water level slightly lower than the lip of Benham Falls.
This water level indicates that not all of the ground water moving
northward in this area is discharged into the Deschutes River and
that some ground water is bypassing Benham Falls. The Deschutes
•
River looses water in the reach below Benham Falls where it flows
adjacent to the Lava Butte lavas.
At Bend, almost the entire flow of the Deschutes River is
diverted into irrigation canals, including the Central Oregon
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Designation
in Figure
A
8
C
O
E
F
Unit
Norn*
Quofernory pyroclastic
deposits
Quaternary lavas
Madras Formation
Columbia River
basalt
John Day forma-
tion
C/orno formation
and older rocks
undifferentiated
Character
Chiefly cinder* associated
with cinder cones.
Chiefly basaltic lava flows
associated with Newberry
Cra'er, ond volcanic erup-
fions in the Cascade Range.
Chiefly stratified layers of
sand, silt, ash, pumice
with some grovel lenses.
Contains some interbedded
lava flows.
Series of basaltic lava
flows.
A sedimentary formation
composed of silt, sand,
and volcanic ash.
Chiefly consolidated sedi-
mentary rocks, volcanic
rocks ond associated pyro-
c) as tics.
Wafer-bearing
CfoarocferiiHci
Rocks of this unit are generally well drained
and not sources of ground water. Where sofur-
ofed they ore capable of yielding large tup-
plies of ground water.
Contains numerous porous lava flows. At most
places are well drained and are unproductive.
Where they are saturated, they are capable of
yielding moderate to large supplies of ground
water.
This formation is in large part fine grained
and not a productive aquifer. At places it
contains permeable lenses of gravel that are
capable of yielding moderate supplies of
ground water. Some of the interbedded vol.
conic rocks ore permeable and are capable of
yielding large supplies of ground water.
Contact zones between individual lava flows
serve as aquifers. This formation is generally
capable of yielding moderate to large supplies
of ground water.
The fine grained character of this formation
precludes it from being a productive source
of ground water.
All of these rocks are believed to be of low
permeability and not capable of furnishing
more than meager supplies of ground water.
:
FROM UNPUBLISHED REPORT - OREGON STATE ENGINEER
FIGURE 3. --MAJOR ROCK UNITS IN THE DESCHUTES
RIVER BASIN
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14
Irrigation Canal which supplies irrigation water in the Redmond
area and the North Unit Canal which supplies irrigation water to
the Madras area. These irrigation canals also serve as sources
of domestic water for a large number of people. The Central
Oregon Irrigation Canal is operated periodically throughout the
year to allow people to fill their cisterns. The City of Madras
utilizes the North Unit Canal for its municipal water supply
during the summer months. The use of irrigation ditches for
domestic water supplies has resulted in the passage of laws that
prevent the discharge of any waste into irrigation ditches and
canals. (See Oregon Revised Statutes 449.545 through O.R.S.
449.567.)
The Deschutes River from just below Benham Falls to below
Cline Falls is a perched stream. The water table at Bend lies
some 500 feet below river level. Below Cline Falls the water
table intersects the river. Figure 4 shows the approximate direc-
tion of ground-water movement in the Middle Deschutes Basin, and
Plates 1, 2, and 3 show the approximate elevation of the water
table.
The barrier of impermeable rock that transects the Deschutes
River Basin near Madras causes all of the ground water to discharge
into the river system. Over 1,400 cfs discharges into the Crooked
River Canyon, and somewhat smaller amounts discharge in the Deschutes
and Metolius Canyons. Some of this discharge now occurs directly
into Lake Chinook, the reservoir impounded behind Round Butte Dam.
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Impermeable
Barrier
Pelton Dam
Chief Area of
Ground-Water
Discharge
Terrebonne
Redmond
Cline Fa)
Benharn Falls
15
FIGURE 4. --MAP OF THE PROJECT AREA SHOWING CHIEF AREA
OF GROUND-WATER DISCHARGE.
ARROWS INDICATE GENERAL DIRECTION OF GROUND WATER -MOVEMENT.
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16
The flow of the Crooked River upstream from the Crooked River
Canyon is very low during the month of August. Therefore, the
flow measured in the Canyon near Culver represents chiefly ground
water discharge. Figure 5 shows the mean August flow for this
station from 1918 to 1960. The rise in flow during this 42-year
period is attributed to a gradual buildup of ground-water storage
caused by irrigation. The entire water yield of the Deschutes
River Drainage Basin is believed to be in the flow of the
Deschutes River as it passes Pelton Dam northwest of Madras.
The August flow of the Deschutes River in this area, which is
almost entirely ground-water discharge, was about 4,000 cfs prior
to the construction of Pelton Dam.
As such a large part of the flow of the Deschutes River comes
directly from ground-water discharge, any operation that could
materially alter the quality of the ground-water resources would
eventually have a direct bearing on the quality of the Deschutes
River system.
Most of the available surface water supplies in the area
south of Redmond have been appropriated and most new water supplies
will depend upon the development of ground-water. The City of
Bend obtains its municipal supply from Tumalo Creek but is currently
planning the construction of a municipal well southwest of town.
The City of Redmond obtains its water from the Deschutes River and
Madras has two wells that are used when canal water is not available.
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1,600
1,500
1,400
1.300
1,200
. 1,100
to
* 1,000
o
1 900
B
£ 800
I 700
3 600
i 500
53
400
300
200
100
0
17
T—i—r-
-i—i—i—r
f*
4J
C
n
o
o
**
<4
*J
< tO
c
V4
I
O
I I I
CO O
•-I CM
O>
o
to
o
^•
0>
o
vO
FIGURE 5. --MONTHLY MEAN AUGUST FLOW FOR THE CROOKED RIVER
NEAR CULVER, OREGON
1918-60 (DATA FROM USGS)
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18
C. Liquid Waste Disposal Practices
1. Sewage Disposal
The typical domestic sewage disposal system in Bend,
Redmond, and Madras consists of an individual septic tank and
a drilled disposal well. Many of the rural systems rely on
septic tanks and conventional drain fields. The septic tank
is either metal or concrete and is placed in a pit that has been
excavated with the help of several charges of dynamite.
The disposal well is usually 6 to 8 inches in diameter
and is completed with several feet of casing at the top to keep
the soil zone from caving into the hole. The top of the casing
is generally a foot or so beneath the surface and is covered
with a concrete slab, hub cap, or some easily available cover.
A drain pipe from the septic tank extends one to two inches
into the disposal well through a hole in the side of the surface
casing. A diagram of a typical disposal well system is shown
on Figure 6, and the construction and installation of a septic
tank is shown on Figure 7.
Disposal wells vary greatly in depth, averaging about
60 feet in Bend and Redmond and well over 100 feet in the Madras
area. At the present time disposal wells are being constructed
for about $3.00 per foot, plus a setup fee for the well drilling
machine. The construction of a sewage disposal well is shown on
Figure 8A.
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Land Surface
Disposal Well
v^^rT^v:-^:^
Inlet;: .^r ^M±lM $&#&i'«-Z$**
Surface Casing
~ Sludge -" '^^T-
Crevices
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20
FIGURE 7
A. PIT BEING EXCAVATED IN
LAVA FOR SEPTIC TANK.
ROCK HAS JUST BEEN
FRACTURED BY DYNAMITE.
•
B. SEPTIC TANK INSTALLED
IN THE PIT SHOWN ABOVE.
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21
FIGURE 8
A. SEWAGE DISPOSAL WELL UNDER CONSTRUCTION AT BEND.
B. OPAL SPRING IN THE CROOKED RIVER CANYON.
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22
Individual sewage disposal systems are generally
operated until the system becomes plugged and sewage backs up
into the system or breaks through to the surface. The chief cause
of failure of a disposal well system is the lack of septic tank
maintenance. The septic tank becomes filled with sludge, and
the excess sludge is carried into the disposal well where it
plugs the cracks and openings in the volcanic rock. Repairs
are generally made by pumping out the septic tank and cleaning
and deepening the disposal well with a well drilling machine.
The practice of "shooting" the disposal wells with dynamite as
a repair operation is falling into disuse.
2. Storm Runoff
The cities of Bend and Redmond use drilled disposal
wells for street drains. These wells are generally located at
the edge of the street and are covered with steel grates. These
disposal wells are usually 6 or 8 inches in diameter and less
than 100 feet in depth. Some penetrate large cracks or joints
in the lava and can dispose of large quantities of water; others
are located in relatively tight lava and are easily plugged with
debris.
3. Farm Drainage
Because many people use irrigation water from the
numerous canals and ditches for their domestic water, there are
restrictions as to the quality of water that can be returned to
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23
the ditches. Irrigation water also collects in some areas where
surface drainage is poor. A number of farm operators in the area
north of Redmond have constructed farm disposal wells for the
disposal of excess irrigation water.
These farm disposal wells (Figure 9) are generally
6 inches in diameter and are completed with perforated casing
installed at the surface. The large annular space excavated
around the perforated casing is backfilled with gravel. Irri-
gation water is fed into the disposal wells directly from ditches,
or the disposal wells may serve as the overflow for farm ponds.
These disposal wells range from about 45 to over 200 feet in
depth. Some can reportedly dispose of several cubic feet per
second (1 cfs = 449 gallons per minute). No method of physically
controlling the injection was observed at the farm disposal wells
examined and all liquid waste coming to the well was injected
into the ground.
As farm drainage has been one of the functions supported
by the U. S. Soil Conservation Service, some of the farm drain
wells in the Redmond area have been constructed with the Federal
Government paying half of the cost.
D. Well and Spring Numbering System
The well and spring numbers used in this report indicate
the township, range, section, and 40-acre subdivision in which
the well, spring, or drain well is located. The first number is
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24
FIGURE 9
A. FARM DRAIN WELL UNDER CONSTRUCTION NEAR REDMOND.
B. TYPICAL FARM DRAIN WELL FOR THE DISPOSAL OF FIELD
RUNOFF.
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25
the range. All of the project area lies south and east of the
Willamette Base Line and Meridian, so the letters "S" and "E"
are omitted. The number following the hyphen indicates the
section and the letter indicates the 40-acre subdivision of a
section as depicted in the following diagram. The number
following the letter is the serial
number of the particular well,
spring, or drain well. For
example, the well numbered 14/13-
28K1 indicates the well is located
in the NW% SE%, Section 28, Township
14 South,. Range 13 East, and is the
first well noted in this 40-acre
D
E
M
N
C
F
I
P
B
G
K
Q
A
H
J
R
tract.
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27
IV. BEND AREA
A. Geology and Occurrence of Ground Water
Most of the Bend Area is underlain by basaltic lava flows
that originated in the Newberry Crater area south of Bend. One
of the more recent flows extends north into the Crooked River
Canyon and forms the intracanyon basalt (Figure 2).
The surficial lava flows in the Bend area have a total
thickness of 100 to 150 feet and underlie most of the area
east of the Deschutes River. These lavas contain some lava
tubes or caves that formed when molten lava flowed out from
beneath a cooled and hardened crust (Figure 10). They also
contain numerous open joints and fractures that give them a
high porosity and permeability. These lavas serve as the chief
zone for the disposal of liquid wastes in both the Bend and
Redmond areas.
These younger lavas generally overlie a sedimentary forma-
tion that contains some interbedded lava flows. Strata in this
formation, which are believed to be part of the Madras Formation,
are generally logged by well drillers as sandstone, conglomerate,
cinders, sand, and gravel. The logs of 22 wells over 400 feet in
depth that are listed in Table 2 of the Appendix. They indicate
that below a depth of 100 feet about 80 percent of the material
penetrated is sedimentary and 20 percent is lava.
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28
FIGURE 10
-
A. ENTRANCE TO HORSE CAVE, A LAVA TUBE LOCATED
NEAR BEND.
B. DISPOSAL SUMP UTILIZED
BY THE BEND MUNICIPAL
SEWER SYSTEM FOR THE
SUBSURFACE DISPOSAL OF
SEWAGE.
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29
The Bend area is also marked by a number of faults. These
generally have a northwestward trend. One lies immediately east
of town where it forms a prominent scarp adjacent to Pilot Butte
(Figure 11). Faults can form either subsurface barriers that
can impound water like a subsurface dam or they may serve as
conduits that can transmit water from shallow to deeper zones.
The hydrologic effects of the various fault zones in the Bend
area are not known at this time.
The regional water table at Bend lies within the Madras
Formation, some 500 to 600 feet below land surface at an alti-
tude of about 3,000 feet. Contours on the regional water table
(Plate 1) show that it has a gentle gradient to the north.
Consequently, ground water in the Bend area flows in a generally
northerly direction.
The first deep test well (18/12-5E1) was drilled by Brooks-
Scanlon, Inc. in 1956. This test well, which is in the City of
Bend, was drilled to a depth of 902 feet. It had a static water
level of 564 feet below land surface and a yield of 1,300 gpm
with 7 feet of drawdown. Since that time, several dozen deep
wells have been drilled in the Bend area for domestic water sup-
plies. These wells are shown on Plate 1 and are described in
Table 1 of the Appendix.
Most of the wells located in Section 8 and 17, T.17S., R.12E.,
north of Bend develop ground water from a perched sand and cinder
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30
zone in the Madras Formation. These wells generally range from
100 to 200 feet in depth while the regional water table is close
to 600 feet below land surface* Most of the perched ground water
in the Bend area is believed to be recharged from canal losses and
irrigation, although some of the perched zones may be recharged
from the Deschutes River. The deepening of a well developing
perched ground water often results in the loss of the perched
water supply out the bottom of the well into the underlying
materials and the creation of a new source of recharge for the
underlying water table.
B. Liquid Waste Disposal
It is estimated that there are more than 3,000 disposal
wells in the Bend area. Most of these are located in and adjacent
to the City of Bend. These disposal wells range from shallow
wells less than 20 feet in depth to deep wells exceeding 200 feet
in depth. The deep wells are confined chiefly to the Awbrey
Butte area in the western part of Bend where there has been con-
siderable difficulty in locating permeable zones for waste dis-
posal.
Most of the disposal wells in Bend are located east of the
Deschutes River. These wells are believed to average about 50
feet in depth and are drilled into the surficial lava flows. The
disposal wells located west of the Deschutes River in Bend are
believed to average slightly deeper, due to the lack of the sur-
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FIGURE II—BLOCK DIAGRAM OF THE BEND AREA SHOWING REPRESENTATIVE WELLS AND THE ALTITUDE
OF WATER LEVELS
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33
ficial lavas, and the necessity of drilling into the less per-
meable sedimentary deposits.
Very few of the disposal wells penetrate into lava tubes or
other large openings in the lava. Most of the wells discharge
waste into open joints or fractures in the lava. Layers of
volcanic cinders are sometimes encountered in disposal wells,
but these porous zones are easily plugged with solids and do not
generally prove satisfactory for waste disposal.
The City of Bend operates a small sewer system that serves
part of the downtown area and a small residential area in the
northeast part of town. This system has a total of 343 connections
and was constructed about 1912.
The raw sewage is discharged into an Imhoff tank located in
SW%, NW%, Section 24, T.17S., R.12E. The effluent from this tank
flows southeast through a pipeline and an open ditch for about
1,500 feet to a small sump that has been excavated into the top
of a lava flow. Downward infiltration from this sump has been the
only method of sewage disposal for the municipal system since it
went into operation more than 50 years ago (Figure 10B).
The Imhoff tank receives very little maintenance and the ef-
fluent is essentially raw sewage. A composite sampler was installed
in the ditch near the discharge sump and hourly samples of the
effluent were collected for a 24-hour period in January 1967.
During this same 24-hour period, a water stage recorder was oper-
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34
ated behind a rectangular weir to provide flow information. The
hourly flow and the amount of suspended solids in the effluent
are shown in Figure 12. A chemical analysis of the composite
sample and chemical analyses of miscellaneous grab samples of the
sewage effluent from this system are given in Table 15 in the
Appendix*
It is possible that the discharge sump overlies a lava tube
in the lava, and that the effluent discharges into such a tube.
Horse Cave, which is located about 2 miles to the east, is typical
of the lava tubes in the Bend area (Figure 10A). If the sump
overlies a lava tube, the effluent would cascade into the tube
through cracks and joints. The effluent would then flow as a
stream down the floor of the tube and collect in depressions.
Losses from the tube would be by downward infiltration into the
underlying lavas. As most of the lava tubes in the Bend area are
relatively ,short, it is doubtful that any subsurface stream of
sewage in a lava tube would extend more than a mile from the
disposal sump. Well logs indicate that the surficial lava is
relatively thin and any lava tube in this area would probably
occur within the first 100 feet below land surface.
The City of Bend has contracted with a consulting engineering
firm to make a study of the sewage collection and disposal problem
in the Bend area. It would appear from the available information
that the existing area of subsurface disposal utilized by the
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35
700
600
E
•
b
"500
•g40O
300
O
CO
1 200
4)
CU
(0
3
100
SUSPENDED SOLIDS
3456789 10 II 12 I 2 3 4 5 6 7 8 9 10 II 12 I 2
January 24, 1967 | January 25, 1967
FIGURE 12. --HOURLY FLOW AND SUSPENDED SOLIDS OF THE EFFLUENT
FROM BEND'S MUNICIPAL SEWER SYSTEM
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36
City could serve as the disposal site for the disposal of
adequately treated sewage. Some geophysical exploration and
test drilling would verify the existence of a lava tube in this
area,
C. Chemical Quality of Ground Water
Most of the ground water developed in the Bend area is low
in dissolved mineral matter. It is slightly alkaline with a pH
of about 8. Chemical analyses of water from 28 wells in the Bend
area are given in Table 3 of the Appendix. The range and average
concentration of the various determinations are as follows:
Range Average
Calcium 4.5-31 mg/1 14 mg/1
Magnesium 1.0-26 mg/1 12 mg/1
Sodium 2.8-27 mg/1 12 mg/1
Alkalinity 32.0-178 mg/1 75 mg/1
Sulfate 0.0-25 mg/1 4 mg/1
Chloride 0.0-15 mg/1 2 mg/1
Phosphate 0.0-0.74 mg/1 .34 mg/1
Dissolved Solids 65.0-223 mg/1 125 mg/1
Hardness 26.0-130 mg/1 59 mg/1
Conductivity ' 66.0-343 (iMHOS 163 (j,MHOS
The test for methylene blue active substance (MBAS) indi-
cates the presence of detergents, a common constituent of most
sewage. The precision of this particular test is about .003 mg/1,
and any determination of .003 mg/1 or less is questionable.
About half of the water wells tested in the Bend area had MBAS
concentrations greater than .003 mg/1.
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37
V. REDMOND AREA
A. Geology and Occurrence of Ground Water
The geology of the Redmond area is similar to that of the
Bend area. The surficial lava is somewhat thinner, generally
averaging less than 100 feet. The lava contains numerous cracks
and joints and serves as the chief rock unit for liquid waste
disposal.
The lava overlies the Madras Formation, which is generally
recorded as sandstone and conglomerate in the water-wells logs.
The logs of many wells in the Redmond area are given in Table 6
of the Appendix, and their locations are shown on Plate 2. The
/
logs of wells 15/13-4H1, -18H1, and -3U1 show that the Madras
Formation extends to depths exceeding 400 feet.
The John Day Formation crops out in the Smith Rock area
northeast of Redmond. This formation is mostly a light colored
tuff that has a low permeability and generally serves as a
barrier to ground-water movement. The John Day Formation is
believed to underlie most of the Redmond area, where its upper
surface serves as the base of the water-bearing formations.
Little ground-water movement would occur in the John Day Forma-
tion or in older underlying formations.
A major period of deformation and erosion followed the deposi-
tion of the John Day Formation. (The Columbia River Basalt
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38
Formation was also involved in this deformation but information
as to the occurrence of the Columbia River Basalt Formation in
the Middle Deschutes Basin is meager). The major valleys eroded
in these older rocks were completely buried by the deposition
of the Madras Formation. The exact locations of these ancestral
valleys in the Redmond area are not exactly known. Their
existence, however, is believed to play a major role in controlling
the occurrence and movement of ground water.
The intracanyon lava, the source of which was in the Newberry
Crater area south of Bend, flowed north and covers a broad area
lying east of Bend and Redmond. This lava flowed into the ancestral
Crooked River Canyon near O'Neil and partially filled the canyon
for at least 30 miles downstream. The intracanyon lava exceeded
400 feet in depth in parts of the Canyon.
The present Crooked River Canyon was eroded into the intra-
canyon lavas and into the Madras Formation. The location of the
present canyon does not exactly coincide with the ancestral one,
and the canyon walls may be composed of either Madras Formation
or intracanyon lava. Many remnants of the intracanyon lava remain
as broad terraces within the present canyon (Figure 2A).
One striking feature in the Crooked River Canyon is the
contact between the intracanyon lava and the Madras Formation.
This contact, which represents the wall of the ancestral canyon,
shows that the ancestral canyon had almost a perfect V-shape.
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39
This is in striking contrast to the differential erosion in the
present canyon (Figure 2), and may be attributed to different
climatic conditions during the two erosion periods.
When the Redmond area was settled, deep well drilling equip-
ment was not readily available, and pumping equipment to with-
draw ground water from great depths was costly. Many early
settlers carried their water for stock and domestic uses. With
the construction of irrigation canals, the "ditch" water became
the chief source of domestic and stock water. Until a few years
ago, there were very few water wells in the Redmond area. This
situation has rapidly changed; problems of maintaining water
quality in the irrigation canals has resulted in the construction
of numerous wells for domestic supplies.
Most of the wells in the area lying north and west of Redmond
are 200 to 300 feet deep, and most of these develop water from a
sand layer, in the Madras Formation. The water table is at an
altitude slightly above 2700 feet in the vicinity of Redmond,
which at most places is 200 to 300 feet below land surface (Figure 13).
Recharge to this water-bearing zone is believed to come chiefly
from canal losses and farm irrigation. The water table in the
vicinity of Redmond has a very gentle slope to the northwest.
The ground water discharges to both the Deschutes and Crooked
Rivers (Plate 2).
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40
B. Liquid Waste Disposal
The City of Redmond has no municipal sewer system and
practically every residence or business establishment has its
own septic tank and disposal well. There is a small area in
the southwestern part of the City that has several feet of soil
overlying the lava where some conventional drain fields have been
constructed and operated successfully.
It is estimated that there are more than 1,000 disposal
wells in Redmond. These range from a few feet to over 100 feet
in depth and are believed to average about 60 feet. Open cracks
and joints in the lavas encountered in these wells serve as the
principal openings for waste disposal.
Practically all of the waste in the Redmond area is domestic
sewage as there are no large industrial waste disposal systems
utilizing disposal wells. The use of wells for disposing of
plywood glue waste was attempted at one time but this method did
not prove feasible.
C. Chemical Quality of Ground Water
Ground water in the Redmond area is slightly alkaline with
a pH of about 8. Chemical analyses of water from 45 wells are
given in Table 7 of the Appendix. These analyses show that the
ground water developed in the Redmond area contains about twice
the amount of dissolved minerals as the ground water sampled
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FIGURE 13 —BLOCK DIAGRAM OF THE REDMOND AREA SHOWING REPRESENTATIVE WELLS AND THE ALTITUDE
OF WATER LEVELS
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43
in the Bend area. The range and average concentration for the
chemical determinations are as follows:
Range Average
Calcium 13-82 mg/1 36 mg/1
Magnesium 4.8-99 mg/1 33 mg/1
Sodium 8.3-49 mg/1 24 mg/1
Alkalinity 56-390 mg/1 182 mg/1
Sulfate 1.0-25 mg/1 9 mg/1
Chloride 0.0-15 mg/1 4 mg/1
Phosphate .12-.62 mg/1 .31 mg/1
Dissolved Solids 93-437 mg/1 245 mg/1
Hardness 60-349 mg/1 153 mg/1
Conductivity 167-681 MHOS 391 MHOS
Forty-four water wells were also tested for methylene blue
active substance (MBAS) which is an indicator for detergents,
and 31 had concentrations that exceeded .003 mg/1.
D. Springs in the Crooked and Deschutes River Canyons
The crooked River Canyon from Smith Rock State Park in
Section 11, T.14S., R.13E. (Plate 2) to Lake Chinook behind
Round Butte Dam is almost one continuous spring area. The
springs discharge from cracks and joints in the intracanyon
lavas and from permeable layers in the Madras Formation. Many
of the springs occur in the bed of the Crooked River or in the
bordering talus slopes and are not visible from the surface.
The largest spring in the Crooked River Canyon is Opal
Spring (Figure 8B) with a flow in excess of 100 cfs (12/12-33G1).
This spring is near river level on the east bank of the Crooked
River in Section 33, T.12S., R.12E. and issues from a permeable
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44
zone in the Madras Formation. The Deschutes Valley Water
District uses water from Opal Spring as a source of domestic
water. The spring water is pumped to a reservoir near the rim
of the canyon, some 900 feet above the spring, and is distributed
throughout the Madras area by gravity flow.
An upper spring at Opal Spring issues from a lava interbed
in the Madras Formation some 100 feet above the main spring
(12/12 -33G2). Chemical analyses of water from these two
springs given in Table 14 of the Appendix show that the water
from the upper spring is appreciably higher in dissolved min-
erals and indicate that the springs do not have a common source.
The ground water supplying the main spring at Opal Spring is
believed to be moving northward from the Bend area in an inter-
bed of lava lying near the base of Madras Formation. Such an
interbed, which was named the Pelton Basalt by Stearns (9),
crops out further downstream.
One of the most interesting springs in the Crooked River
-»
Canyon occurs on the west wall of the canyon a few miles up-
stream at the George Bell Ranch (13/12 -14F1). This spring,
which has been described by Stearns in his report on the Middle
Deschutes River Basin, issues from a contact zone in a lava
interbed in the Madras Formation. This interbed is composed of
several lava flows and forms a vertical cliff that extends along
both sides of the canyon. The spring discharges from a zone
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45
lying about midway down the vertical cliff and about 100 feet
above river level. At one time the available head was utilized
to develop power and operate rams, but the water now being used
from these springs is pumped by means of a turbine pump that is
hung down the face of the cliff. The unusual occurrence of this
spring, some 100 feet above river level, was pointed out by
Stearns. The Crooked River Canyon at this point does not exactly
coincide with the ancestral canyon that was partially filled
with the intracanyon lavas, and the center of the ancestral
canyon lies slightly to the west of the present canyon. As both
the ancestral canyon and the present canyon extend to approxi-
mately the same depth, the contact zone breeding this spring
must be cut by the contact with the intracanyon lavas a short
distance back from the outcrop area. It is probable that the
ground water supplying this spring is moving northward through
the intracanyon lavas and is impounded in the ancestral canyon by
a change in permeability in the lavas. The impounded ground water
spills over into the present canyon via the permeable contact
zone in the lava interbed.
Visible springs are not common in the Deschutes River Canyon,
however, a large spring that issues from an intracanyon lava flow
along the east bank of the Deschutes River in the SW% SW% Section
34, T.13S., R.12E. was observed and sampled. The water issues
in a line of springs some 20 feet above the river. Another spring
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46
was observed, but not visited along the west bank of the Deschutes
River in the NEfc SW£ Section 5, T.13S., R.12E.
The springs in the Crooked River Canyon vary appreciably
in chemical quality. The chemical analyses of water from a few
of these are given in Table 14 of the Appendix. As the gradient
of the Crooked River is somewhat steeper than the northward dip
of the strata in the Madras Formation, ground water issues from
older or deeper strata progressively downstream. The ground
water lowest in dissolved mineral matter moves through permeable
strata near the base of the formation and discharges to the river
in and near Opal Spring. This water is very similar in quality
to some of the ground water developed in Bend area, being very
soft and having total dissolved solids in the order of 100 mg/1.
Further upstream the water from springs located in Section 32,
T.13S., R.13E. is hard and total dissolved solids average about
240 mg/1. This water is very similar to ground water in the
Redmond area. This difference in water quality indicates that
the ground water within the Madras Formation is stratified by
confining layers and that the water improves in quality with depth
in the formation. Water similar in quality to that of Opal Springs
probably occurs near the base of the Madras Formation in parts of
the Redmond area.
The difference in water quality in the springs in the Crooked
River Canyon indicates that the water has a different history.
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47
One aid in interpreting the history of the water is its age since
falling as precipitation. One method of dating water is by its
tritium content.
Tritium is a radioactive isotope of hydrogen that is produced
by cosmic rays in the atmosphere. It has a half life of about 12.5
years. The natural tritium content of rainwater prior to the
introduction of large amounts of tritium to the atmosphere from
thermonuclear explosions was in the order of 5 Tritium Units.
A Tritium Unit (T.U.) has been defined as follows:
1 T.U. = Tritium Atoms x 1018
Hydrogen Atoms
A Tritium Unit is equivalent to about 0.008 tritium dis-
integrations per minute per milliliter of water. With electro-
lytic enrichment and gas counting, the minimum detectable activity
is 0.3 T.U. or a maximum age of about 50 years. Since there has
been so much tritium contamination since 1954 a tritium assay
of water at this time can generally tell whether the water is post
1954 in age, older than 1917, or somewhere in between.
Five samples of spring water were collected on May 22, 1967,
from springs in the Crooked and Deschutes River Canyons for tritium
assays. The assays were made by Isotopes, Inc., Westwood, New
Jersey. The sampling points and the assay results are as follows:
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48
SOURCE OF SAMPLE TRITIUM ASSAY
Zllko's Spring located in the
Crooked River Canyon in the
SE% SE%, Section 32, T.13S.,
R.13E. 19.5 - .8 TU
George Bell Spring located in
the Crooked River Canyon in
the SE% NW%, Section 14,
T.13S., R.12E. - - 4.5- .4
Upper Spring at Opal Spring
located in the Crooked River
Canyon in the SW% NE%,
Section 33, T.12S., R.12E. 16.8 * .8
Lower Spring at Opal Spring
located in the SW% NE%,
Section 33, T.12S., R.12E. 1.4 * .3
Unnamed spring in the Deschutes
River Canyon in the SW% SW%,
Section 34, T.13S., R.12E. 4.2 - .3
These assays indicate that the water from the Lower Spring at
Opal Spring entered the ground prior to any contamination from
thermonuclear testing and is in the order of 23 years in age (1944)
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49
If the water from Opal Spring is recharged from the Deschutes
River just downstream from Benham Falls, the ground water velocity
has averaged about 9,000 feet per year or about 25 feet per day.
If the recharge occurs further upstream, the velocity would be
proportionally faster.
The water samples from the other four springs show the effect
of tritium contamination from thermonuclear testing and are
appreciably younger than the sample from Opal Springs. In general,
the ground water moving through the strata lying near the base of
the Madras Formation is older than ground water moving through
overlying strata* This is believed due to the large amount of
recharge to the shallower strata from irrigation, canal losses,
and disposal wells. Annual sampling of water from Opal Spring
for tritium assays would provide an arrival time of the first
wave of tritium contaminated water and would give a more accurate
measure of the ground water travel time for the spring.
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51
VI. MADRAS AREA
A. Geology and Occurrence of Ground Water
The City of Madras is located in a valley that is separated
from the Deschutes River by a broad lava-capped plateau named
Agency Plain. Drainage from Madras flows to the Deschutes River
through the deep narrow canyon of Willow Creek, which cuts through
Agency Plain (Plate 3). The city is underlain by the Madras
Formation. The low permeability of some of the sedimentary strata
in this formation has resulted in the widespread use of drilled
wells for waste disposal.
The rural area around Madras obtains most of its domestic
/
water from Opal Spring through the Deschutes Valley Water District
System. The widespread availability of this excellent water has
resulted in the construction of very few water wells in the area.
The City of Madras obtains its municipal water from the North
Unit Irrigation District canal during the irrigation season. This
water is diverted from the Deschutes River at Bend. During the
non-irrigation season, the municipal system is supplied by two
deep wells located at the north edge of town. The No. 1 well
(11/13 - 1D1) was drilled about 1910 and has been in use since
that time. It is 415 feet deep and develops water from a gravel
stratum in the Madras Formation. Well No. 2, which was drilled
in 1966, is 451 feet deep and also develops water from a gravel
stratum in the Madras Formation. The static water level in this
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52
well was 326 feet below land surface in 1966. The logs of
these two wells are given in Table 10 of the Appendix.
The water table at Madras is at an altitude of about 1900
feet (Figure 14). It is believed to have a gradient to the
northwest beneath Agency Plain towards the Deschutes River and
Lake Simtustus, the reservoir behind Pelton Dam. The depth to
the water table exceeds 500 feet beneath Agency Plain.
A perched ground-water body occurs at shallow depth beneath
most of the City of Madras. The water occurs in gravel and
sandstone and is perched by an impermeable layer of sandstone
in the Madras Formation. At places, the perched ground water
occurs at depths less than 20 feet below land surface. The
water is used for lawn irrigation and other non-domestic uses.
B. Liquid Waste Disposal
It is estimated that there are in the order of 500 disposal
wells in the Madras area. Some near surface layers of tuff and
sandstone have restricted the operation of drainfields and have
made the use of drilled wells the local method of waste disposal.
The disposal wells at Madras are generally deeper than those
at Bend and Redmond and are believed to average over 100 feet.
Some of the disposal wells on Agency Plain extend to depths of
300 feet or more in order to encounter a permeable stratum.
A permeable unsaturated lava interbed in the Madras Formation
is generally encountered between 80 to 150 feet below land surface
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FIGURE 14—BLOCK DIAGRAM OF THE MADRAS AREA SHOWING REPRESENTATIVE WELLS AND THE ALTITUDE
OF WATER LEVELS
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55
within the City of Madras. This interbed serves as the chief
zone for waste disposal. The perched ground-water zone, which
occurs beneath most of the City, overlies this lava interbed.
The disposal wells are generally cased through the perched zone
to keep them from caving and to reduce the recharge into the
perched zone.
The lava interbed used for waste disposal at Madras con-
tains a sizable reservoir of air. Changes in atmospheric
pressure cause pressure differences to develop between the
atmosphere and the confined air reservoir. Such pressure dif-
ferences cause many of the disposal wells to blow or suck air,
depending upon whether a high or low atmospheric air mass is
moving into the area. As many of the disposal wells are not
vented at the well, the blowing or sucking of air generally
occurs at the plumbing vent on the roof of each house. It was
reported that one can hear the roar or whistle of air moving in
or out of these vents throughout the City on some still nights.
The disposal wells at the town of Metolius southwest of
Madras, are believed to average about 60 feet in depth. The
waste is discharged into the surface lava that underlies most
of Agency Plain.
C. Chemical Quality of Ground Water
Water from the deep city wells at Madras contain about the
same amount of dissolved minerals as ground water in the Redmond
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56
area. It is higher in sulfate and chloride, but is lower in
phosphate. The following is a chemical analysis of water from
City Well No. 1 (11/13-1D1):
Silica 54 mg/1
Calcium 41 mg/1
Magnesium 27 mg/1
Sodium 31 mg/1
Alkalinity 141 mg/1
Sulfate 27 mg/1
Chloride 14 mg/1
Phosphate .03 mg/1
Dissolved Solids 276 mg/1
Hardness 157 mg/1
Conductivity 399 MHOS
Samples of some of the perched ground water at Madras show
that it is much higher in dissolved mineral matter than the
deeper ground water. The total dissolved solids from three
shallow wells at Madras averaged more than 600 mg/1. This is
believed to be caused by the recharge of irrigation water and
disposal well waste. The MBAS in the perched ground water
samples tested was very low.
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57
VII. DISCUSSION
A. Pollution Threat Caused by the Operation of Disposal Wells
Water discharged into the ground percolates downward through
the openings occurring between the soil and rock particles. This
water replaces soil moisture deficiencies and the excess contin-
ues to percolate downward due to the pull of gravity. It con-
tinues downward until it encounters a zone in which all of the
voids or openings in the rock material are filled with water.
This zone, which is called a "zone of saturation," may begin at
the regional water table or may be a zone perched above the
regional water table by a stratum of low permeability. At
places water may pass through several perched zones on its route
to the regional water table.
Water in a zone of saturation is under hydrostatic "pressure.
Differences in pressure from place to place create the hydraulic
gradient or slope that provides the energy for the movement of
water. Unless the water collects within a zone of saturation,
there is little lateral movement.
Once the waste water or effluent from a septic tank reaches
a perched or regional water table, it flows down the hydraulic
gradient. As most ground-water flow is under laminar conditions,
there is much less dispersion of the effluent in ground water
than in surface water. The problem of tracing a particular waste
from a particular source without constructing numerous observation
wells is very difficult.
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53
In the ground disposal of waste, all water that is not
evaporated, transpired back into the atmosphere from the soil
zone, or consumed in replacing soil moisture deficiencies will
recharge some underlying ground-water zone. In a conventional
drainfield disposal system, a part of the effluent generally
passes into the atmosphere by evapotranspiration from within
the soil zone, while in a disposal well system there may be
little or no fluid loss to the atmosphere. In a conventional
drainfield there is a certain amount of biological treatment
and chemical sorption that takes place in the soil zone that is
bypassed in a disposal well system. Any further biological
treatment and chemical sorption that may occur between the soil
zone and the underlying ground-water zone is further reduced by
the use of a disposal well.
The chief difference between a conventional drain-field
disposal system and a disposal well system is in the quantity
of effluent and the degree of natural treatment the waste receives
before it recharges an underlying ground-water zone. Any system
that increases the quantity of subsurface waste and reduces the
degree of natural treatment increases the threat of ground-water
pollution. In order to reduce the threat of ground-water pollu-
tion from ground disposal of sewage to the minimum, the waste
should be spread or injected as close to the surface as possible.
Where the soil or rock conditions would make near surface disposal
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59
systems inoperative, restrictions on the construction and oper-
ation of ground disposal systems would be desirable.
Well records show that numerous perched ground-water zones
have developed in the Middle Deschutes Basin. These are generally
recharged from irrigation and canal losses, although some recharge
comes from waste disposal systems. In some parts of the area,
the perched ground water is being developed and used in domestic
water systems. With more and more ground disposal systems going
into operation each year, the number of perched zones will in-
crease and spread over larger areas.
One of the most serious threats to the quality of the regional
ground-water supply will develop where deep uncased water wells
extend to the regional water table. Of the 124 wells over 200
feet in depth listed in Tables 1, 5, and 9, 30 have casings
extending to 20 feet or less from land surface. As the perched
water zones develop and spread, they will intersect the existing
water wells. Where these wells are uncased, the perched ground
water will cascade down the well and recharge the regional ground-
water supply. Figure 15 depicts how such mixing can take place.
As long as there is subsurface disposal of sewage and other liquid
waste, there will always be a threat to ground-water quality.
Some liquid waste receives little alteration in the ground
and could cause very serious water quality problems. Such wastes
as brines, petroleum products, some fertilizers, and some other
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60
Water Well
' N ^ / ' N
\ N \
\'N
\ —
v \
Disposal Well
/ -\ *-
" _ ' ' > ^IS
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FIGURE 15. --DIAGRAM SHOWING HOW AN UNCASED WATER WELL
CAN SERVE AS A CONDUIT FOR THE MOVEMENT OF PERCHED WATER
TO THE REGIONAL WATER TABLE
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chemical wastes should never be discharged into the ground where
ground water is being developed for domestic use. Once the under-
lying ground-water reservoir becomes polluted with these wastes,
the abatement of the source of pollution will not remove pollution
in the water supply, and the supply may remain unusable for many,
many years.
In some operating ground disposal systems, the effluent is
chlorinated prior to discharge to the ground. This practice would
tend to restrict further biological action in the ground and may
result in a poorer quality water recharging the underlying water
zones.
In light of the waste disposal methods used in the Middle
Deschutes Basin, the question arises as to why the ground-water
resources of the area are not already grossly polluted. The
answer to the question involves many factors including the follow-
ing:
1. The volume of liquid waste is very small when com-
pared to the volume of ground-water recharge coming from canal
and irrigation losses, and even smaller when compared to the total
quantity of ground water moving through the area.
2. Most of the waste is domestic sewage which does not
result in a marked chemical effect on water quality when compared
to some industrial and chemical wastes.
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3, The water wells used to sample water quality are
not generally located at sites where sampling would be desirable,
and the available water quality information may give a misleading
picture of the overall ground-water conditions. For example,
the closest well located down gradient from Bend's sewage dis-
posal sump is about 4 miles away.
4. The sedimentary layers underlying the surficial
lavas serve as effective filters for the removal of all suspended
solids, and the great depth to the water table aids in the sorption
of some chemicals.
B. Methods of Reducing the Threat of Ground Water Pollution
1. Casing of Deep Water Wells
As mentioned in the last section, deep, uncased water
wells can provide direct conduits where perched ground water can
gain direct access to the water table. With the construction of
more and more deep water wells in the area and the disposal of
more and more waste to the ground, the threat of ground-water
pollution caused by uncased water wells will become serious.
One method of reducing this threat is the casing and
pressure grouting of deep water wells. In order to case a well
drilled in lava or consolidated rock, the well bore must be
drilled with a greater diameter than the outside diameter of the
casing. An 8-inch bit would generally be required to drill a
6-inch cased well. This oversize well bore results in an annular
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space around the casing that can also serve as a conduit for
the movement of water. In order to eliminate this added threat,
the annular space should be sealed with cement grout. The very
high porosity of the surficial lavas may be too great to obtain
an effective grout seal near the surface, but an effective seal
can be obtained in the underlying sedimentary rocks. Such con-
struction methods would materially increase the cost of water
wells, but they would provide good insurance in protecting the
quality of the water supply.
The Oregon State Engineer (4) has issued "General
Standards for the Construction and Maintenance of Water Wells."
These existing standards, which prescribe the materials to be used
and methods of constructing water wells, are not adequate to
cope with the special situation common to the Bend, Redmond, and
Madras areas. It is therefore recommended that special standards
be adopted for this area so as to eliminate the threat of ground-
water pollution caused by the construction of deep uncased water
wells.
2. Elimination of Disposal Well Construction
Another method of reducing the threat of ground-water
pollution would be the elimination of further disposal well con-
struction. This could be accomplished by state statutes or local
ordinances. In some areas of the state, individual sewage dis-
posal systems must be approved by the local health department.
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This is generally accomplished through a system of permits and
inspections. Such a system could be utilized in enforcing a
regulation banning the use of new disposal wells.
There are some parts of the Madras area and parts of
the Awbrey Butte area at Bend where the low permeability of the
soil would make conventional drainfield disposal systems inoper-
ative. Further development of such areas of low soil permeability
should await the availability of municipal sewers.
Another effective method of reducing disposal well con-
struction could come from regulations of the State and Federal
home finance agencies. If the availability of funds for financing
new homes were dependent upon an approved sewage disposal system,
other methods of sewage disposal would soon be adopted.
3. Abatement of Existing Disposal Wells
The abatement of existing sewage disposal wells presents
a much more complex problem than the casing of deep water wells
or the prevention of new disposal well construction. At many
homes, sufficient land area for drain-field disposal systems is
not available. In the business districts, the disposal wells are
generally located in the alleys, and adequate space for drain-
fields is not available.
As most of the existing disposal wells in the Deschutes
Basin are located in the cities of Bend, Redmond, and Madras, the
construction of municipal sewers and treatment plants in these
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three cities would eliminate the need for most of the disposal
wells in the area. When such systems are constructed, a program
for the systematic plugging of all abandoned disposal wells
should also be initiated.
In order to achieve better disposal practices, Federal,
State, and local government agencies should take the lead in
eliminating their use of disposal wells wherever possible. An
inventory of Federally-owned or operated disposal wells in the
project area showed the following:
Number of Disposal Wells
Agency Owned or Used
U. S. Forest Service 20
U. S. Bureau of Land Management 1
Bonneville Power Administration 4
U. S. Post Office, Redmond 1
Soil Conservation Service 1
Farmers Home Administration 1
At some of these sites, conventional tile drain fields
could replace the disposal wells so as to provide a better example
of waste disposal practices.
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VIII. SELECTED REFERENCES
1. Henshaw, F. F., "Deschutes River, Oregon, and its Utilization,"
U. S. Geological Survey, Water Supply Paper 344, 1914.
2. Hodge, E. T., "Geology of the Madras Quadrangle," Oregon State
Monographs, Studies in Geology No. 1, 1941.
3. Municipal Water System, City of Bend, an engineering report by
Cornell, Rowland, Hayes and Merryfield, Corvallis,
Oregon, December 1964.
4. Oregon State Engineer, Rules and regulations prescribing
general standards for the construction and maintenance
of water wells in Oregon, 1962.
5. Oregon State Water Resources Board, "Deschutes River Basin,"
Salem, Oregon, 1961.
6. Santos, J. F., "Quality of Surface Waters in the Lower Columbia
River Basin," U. S. Geological Survey Water Supply Paper
1784, 1965.
7. Sceva, Jack E., "A Brief Description of the Ground Water Resources
of the Deschutes River Basin," Unpublished report of the
Oregon State Engineer prepared for the Oregon Water
Resources Board, 1961.
8. Sewage Facilities, City of Madras, an engineering report by
Cornell, Howland, Hayes and Merryfield, Corvallis,
Oregon, July 1964.
9. Stearns, Harold T., "Geology and Water Resources of the Middle
Deschutes River Basin, Oregon," U. S. Geological Survey
Water Supply Paper 637-D, 1930.
10. United States Reclamation Service "Deschutes Project" Cooperative
report of the United States Reclamation Service and the
State of Oregon, 1914.
11. Williams, Howell, "A. geologic map of the Bend quadrangle,
Oregon and a reconnaissance geologic map of the central
portion of the high Cascade Mountains," Oregon Department
of Geology and Mineral Industries, 1957.
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