EPA-600/2-77-117
June 1977
Environmental Protection Technology Series
CONTINUOUS SUBSURFACE INJECTION OF
LIQUID DAIRY MANURE
Robert S. Kerr Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Ada, Oklahoma 74820
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-77-117
June 1977
CONTINUOUS SUBSURFACE INJECTION OF
LIQUID DAIRY MANURE
by
J. L. Smith
D. B. McWhorter
R. C. Ward
Colorado State University
Fort Collins, Colorado 80523
Grant No. S-802940
Project Officer
S. C. Yin
Source Management Branch
Robert S. Kerr Environmental Research Laboratory
Ada, Oklahoma 74820
ROBERT S. KERR ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
ADA, OKLAHOMA 74820
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DISCLAIMER
This report has been reviewed by the Robert S. Kerr Environmental
Research Laboratory, U.S. Environmental Research Laboratory, and approved
for publication. Approval does not signify that the contents necessarily
reflect the views and policies of the U.S. Environmental Protection Agency,
nor does mention of trade names or commercial products constitute endorsement
or recommendation for use.
ii
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FOREWORD
The Environmental Protection Agency was established to coordinate admin-
istration of the major Federal programs designed to protect the quality of
our environment.
An important part of the agency's effort involves the search for infor-
mation about environmental problems, management techniques and new technologies
through which optimum use of the nation's land and water resources can be
assured and the threat pollution poses to the welfare of the American people
can be minimized.
EPA's Office of Research and Development conducts this search through a
nationwide network of research facilities.
As one of these facilities, the Robert S. Kerr Environmental Research
Laboratory is responsible for the management of programs to: (a) investigate
the nature, transport, fate and management of pollutants in groundwater;
(b) develop and demonstrate methods for treating wastewaters with soil and
other natural systems; (c) develop and demonstrate pollution control tech-
nologies for irrigation return flows; (d) develop and demonstrate pollution
control technologies for animal production wastes; (e) develop and demonstrate
technologies to prevent, control or abate pollution from the petroleum refin-
ing and petrochemical industries; and (f) develop and demonstrate technologies
to manage pollution resulting from combinations of industrial wastewaters or
industrial/municipal wastewaters.
This report contributes to the knowledge essential if the EPA is to meet
the requirements of environmental laws that it establish and enforce pollu-
tion control standards which are reasonable, cost effective and provide
adequate protection for the American public.
William C. Galegar
Director
Robert S. Kerr Environmental Research
Laboratory
iii
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ABSTRACT
The research has involved the development and evaluation of an efficient,
economical, continuous subsurface injection machine. The application site
was instrumented so the quality of water percolating beneath the injection
zone could be measured. Wells located around the sites were used to monitor
groundwater quality. Soil samples were taken periodically to determine
nutrients, salts, heavy metal concentrations, and bacteria movement and
survival.
Major environmental problems were increased soil salinity and movement
of fecal coliform to the groundwater. Both of these problems can be elimi-
nated by proper management and site selection.
Subsurface injection is economically feasible when compared with other
methods of land application. Although capital costs are greater for sub-
surface injection, labor costs are significantly reduced. Other advantages
of subsurface injection are elimination of odors, insects and visual
pollution and minimization of runoff pollution.
This report was submitted in fulfillment of Grant No. S-802940 by
Colorado State University under the partial sponsorship of the U.S.
Environmental Protection Agency. This report covers a period from
January 21, 1974, to December 1, 1976, and work was completed as of
September 30, 1976.
iv
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CONTENTS
Page
Foreword ill
Abstract iv
List of Figures vi
List of Tables vii
Acknowledgements viii
Sections
I Conclusions 1
II Recommendations 3
III Introduction 4
IV Site Description and Experimental Procedures 13
V Environmental Monitoring 21
VI Economic Comparisons 35
VII Application Example 41
VIII References Cited 44
IX List of Publications 46
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FIGURES
Number Page
1 Original subsurface injector 7
2 Subsurface injector sweep and deflector 7
3 Boulder subsurface injector 9
4 Fort Collins subsurface injector 9
5 Fort Collins subsurface injector adapted for
use in frozen ground 12
6 Injector for frozen ground 12
7 Manure injection site 14
8 Vacuum extractors 17
9 Soil electroconductivity on plots 1 and 2 25
10 Soil electroconductivity on plots 3 and 4 26
11 Colorado State University's Dairy location 42
vi
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TABLES
Number Page
1 Seven Sweep Injector Specifications , . , . . 10
2 Injector Size Range 10
3 Summary of Manure Loading 16
4 Dairy Manure Analysis 22
5 Coliform Analysis in Soil Samples 22
6 BOD, COD and Fecal Coliform in Water and
Manure Samples 23
7 Vacuum Extractor Sample Analysis 27
8 Initial Groundwater Quality 28
9 Analysis of Groundwater Samples 29
10 Soil Analysis 32
11 Silage Corn Yield and Germination Data 33
12 Analysis of Corn Leaf and Grain Samples 34
13 Estimated Initial Investment and Annual Costs for a
Liquid Manure Storage and Tank Spreading System .... 36
14 Estimated Initial Investment and Annual Costs of
Disposal for a Liquid Manure Storage and Continuous
Subsurface Injection System 37
15 Estimated Initial Investment, Annual Costs and
Labor Requirements for Alternative Waste
Management Systems 39
vii
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ACKNOWLEDGEMENTS
The authors wish to thank Sherm Worthington, Larry Wyatt, James Honn,
and Steve Smith for their assistance during the term of this project. They
willingly went to the site in all types of weather and often had to perform
rather unglamorous tasks.
The assistance of Mr. S. C. Yin and Mr, L. R. Shuyler of the Robert S,
Kerr Environmental Research Center is gratefully acknowledged. Their many
suggestions and interest contributed significantly to the success of this
project.
Chemical analysis of the plant, soil and water samples was conducted by
the CSU Analytical Chemistry Facility under the direction of Dr. William S.
Ferguson. Mr. Kirke Martin and Dr. S, M. Morrison performed the biological
analysis. The authors wish to express their appreciation to these individuals
for their assistance.
Finally, the authors wish to thank Mrs. Peggy Stumpf and Mrs. Phylis
Sitzman for their excellent work in preparation of this report.
J. L. Smith
D. B, McWhorter
R. C. Ward
viii
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SECTION I
CONCLUSIONS
Continuous subsurface injection provides an efficient method for land
application of liquid manure. Using the system, it is possible to apply at
high rates (1,500-3,800 fc/min typically), and achieve relatively high loading
rates (up to 748,000 &/ha) per application. Applications can be repeated
weekly or more often, depending upon the type of equipment used.
Odor, insect, runoff and visual pollution are eliminated with subsurface
injection. Liquid manure is pumped from the holding facility through a com-
bination of permanent and portable pipe and a 200-meter flexible hose to the
injector. The injector applies the manure in a broad, shallow cavity,
approximately 12 cm below the ground surface, and thoroughly mixes it with
soil. The manure is completely covered with soil and is never exposed. A
modified injection system was used for frozen ground. In this case,
approximately 70% of the injected area was covered.
A 0.49 ha site was adequate for application of 95,000 liters of 1.2%
solids manure each month from September 1974 through March 1975. The maximum
total application was 3.5 x 106 A/ha or 42,000 dry kg/ha. This area should
be adequate for an unlimited time period, provided precautions are taken to
control soil salinity.
Soil salinity and fecal coliform contamination of the groundwater were
major environmental problems. Natural precipitation may be adequate for con-
trol of soil salinity in some regions; however, natural precipitation may not
be adequate in semiarid regions. In this case, it may be necessary to
irrigate areas to leach salts out of surface soils.
Contamination of groundwater by fecal coliform appears to be related to
the specific site. The groundwater was within 0.5 m of the ground surface
during the irrigation season. This did not provide adequate filtration for
the fecal coliforms. Also, the groundwater passed through home sewage dis-
posal systems in the vicinity of the site, thereby increasing the fecal
coliform concentration. The groundwater should be more than 1 m below the
surface of sandy loam soils to prevent fecal coliform contamination.
The manure applied to the site provided adequate crop nutrients to
produce silage corn yields similar to those produced by normal cultivation
and fertilization. Chemical analysis of leaf and grain samples indicated
that heavy metals were not concentrated in plant tissues.
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Subsurface injection is an economical method for land application of
liquid manure. Although capital costs are relatively high, operating costs
are significantly reduced. For example, direct surface spreading of the
manure from a 100-cow free-stall dairy in solid form required 504 hours per
year. Subsurface injection of liquid manure from the same dairy required
only 324 hours per year.
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SECTION II
RECOMMENDATIONS
The subsurface injector was successful in applying the relatively small
quantity of manure generated by the dairy described in this report. The
injection system should now be studied in a much larger system, i.e., one
which generates approximately 30,000 liters per day. This would better
define the system's limitations and enable a more thorough study of the
environmental impact.
Soil salinity was a major problem in this research. The movement and
control of salts in the soil above the water table should be studied.
Methods of controlling the movement of salts to the groundwater may be
required if land application of liquid manure is to be economically suc-
cessful. In other words, salts must be removed from surface soil for crop
growth. However, it may also be necessary to limit their movement into
the groundwater. Thus, a method of controlling movement of salts would
be desirable.
Movement of nitrates to the groundwater may also be a limiting
environmental factor for land application of manure. The mineralization
of nitrogen from manure and movement of nitrates in the soil should be
studied. This should generate a series of recommendations with regard
to suitable application sites and loading rates. Most of the current
recommendations appear to be very conservative.
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SECTION III
INTRODUCTION
Modern methods of animal production involve intensive use of capital to
reduce labor .costs and increase production efficiency. This has resulted in
the practice of feeding large numbers of animals in confined areas generally
near population centers. Advantages of this system are that it permits
mechanization of feeding, use of controlled environments, and the production
of large numbers of animals near processing plants or markets. The major
problem with confinement feeding is the disposal of large quantities of
manure produced by the animals.
Liquid manure systems are popular in confinement feeding operations.
Liquid manure systems utilize pumps, tanks, pipelines, etc., rather than the
normal inefficient bulk handling equipment used with dry or semisolid manure.
In addition, water can be used for flushing and cleaning feeding areas.
However, manure must still be disposed of, regardless of the handling system
or its efficiency.
Yeck and Schleusener (1971) discussed processing of manure for refeeding
and other uses. While this should represent the most desirable method of
recycling, developmental work is still required. Also, the acceptability of
refeeding manure has not been resolved. Until these problems are solved,
processing and refeeding of manure cannot be regarded as an acceptable
disposal method.
Methods ranging from lagoons and oxidation ditches to municipal
treatment plants have been studied, used, or proposed for treatment of
animal wastes. Success of treatment operations has varied with location and
management. Full treatment is expensive because of the large quantity of
material involved and the relatively high solids concentration. Other treat-
ment processes require good management and strict supervision to avoid
nuisance and other pollution hazards. All forms of treatment produce sludges
which require safe methods of ultimate disposal or recycle.
A subsurface injection system was developed by Colorado State University
(Gold et al., 1973). With this system, it is possible to recycle large
quantities of material on relatively small land areas and avoid nuisance pol-
lution. The system eliminates the need for treatment and is highly efficient,
inexpensive, and particularly suited for recycle of material near populated
areas. Development of the technology for injection of manure would provide
an acceptable method of recycling manure until more sophisticated processing
methods are developed.
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OBJECTIVES
The overall objective of the research is to evaluate environmental
problems and costs associated with recycling of liquid livestock manure on
agricultural land through subsurface injection. This includes determination
of the following:
1. The potential for contamination of ground and surface water.
2. The land requirements for disposal.
3. The minimum depth of injection required to keep material covered
and prevent it from being washed away with rainfall and/or
irrigation waters.
4. Any odors and/or insect problems.
5. The availability of plant nutrients, soil contamination by salts
and fecal coliforms, and the effect on crop yield.
ON-LAND DISPOSAL
Land spreading has been used to dispose of manure for centuries.
Although manure has limited value as a source of plant nutrients, it does
produce some benefit in terms of improved soil tilth and/or as a soil con-
ditioner. The normal practice of land disposal involves bulk collection of
manure, transport to a disposal area and surface spreading. The manure is
then incorporated into the soil during normal tillage operations at some
later time.
Surface spreading of manure can result in a serious deterioration in the
quality of runoff (Bernard et al., 1971; U.S. EPA, 1971a). Further surface
application near populated areas often results in problems of aesthetics and
various forms of nuisance pollution, such as odors and insects. Because of
these problems, future use of surface spreading appears to be limited to
situations where conditions can be carefully controlled.
Injection of waste material beneath the ground surface eliminates many
of the difficulties associated with surface spreading. Subsurface injection
has the following distinct advantages:
1. Eliminates odor and insect problems.
2. Minimizes contamination of runoff waters for effective pollution
control.
3. Adds organic matter to the soil and thus acts as a soil conditioner
and source of plant nutrients.
4. Eliminates viewing by the public and is thus aesthetically more
acceptable.
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5. Is economical.
The unique feature of the injection system developed at Colorado State
University is that material is discharged uniformly and at shallow depths
under the wings of wide sweeps, while the tilling action of the sweeps mixes
it with soil. Experience gained in current research has indicated that this
procedure is desirable for the following reasons:
1. Thorough mixing produces a large interface area between the
material and soil. Because of the capillary attraction of the
soil, water moves into the soil and the injected material dries
rapidly. The soil then dries, primarily by movement of water to
the soil surface. This decreases the possibility-of groundwater
contamination and permits injections at greater frequency.
2. The material is maintained in an aerobic environment, thus
eliminating the possibility of mummification.
3. Less tractor drawbar power is required to pull the injector
through the soil, thereby reducing disposal costs.
The injectors can be operated at depths ranging from 7.5 to 25 cm.
Liquid waste having 5% solids is fully covered at an operating depth of 7.5
to 12.5 cm, with up to 5,300 &/min discharge and ground speed within the
range of 0.8 to 2.4 km/hr (187,000 to 748,000 £/ha).
The current machine has been used with sewage sludge having a solids
content up to 10%. However, 5-6% solids is considered optimum because of
difficulties in pumping thicker material through the machine and because
lower solids contents significantly increase the volume of liquid that must
be handled.
DESIGN OF THE SUBSURFACE INJECTION EQUIPMENT
A series of laboratory tests (Gold et al., 1973) was conducted to study
various methods of injecting liquid, organic wastes with up to 6% solids into
the soil. The optimal procedure was determined to be one where the material
was thoroughly mixed with the top 10 cm of soil. This procedure resulted in
the most rapid drying of the liquid portion of the material and also facili-
tated repeated applications in the shortest time interval. Deep injections
dried slowly and resulted in near mummification of the injected material.
The first subsurface injector system, shown in Figure 1, consisted of a
2,840 liter portable tank and the injector pulled behind the tank. The major
accomplishment of this phase of the research was the development of the
injector units. These consisted of commercially available spring-loaded
chisel plow shanks with 40 cm wide, high-lift sweeps. The liquid waste is
discharged under the wings of the sweep through a deflector mounted on the
rear of the shank, as shown in Figure 2.
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Figure 1. Original subsurface injector,
-
Figure 2. Subsurface injector sweep and deflector.
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As the sweep passes through the soil, it creates a broad, shallow cavity
into which the liquid waste is injected. Soil falls over the wings of the
sweep, filling the cavity and mixing with the waste. The covering soil also
fills the vertical slot formed by the shank, leaving the soil surface rela-
tively undisturbed. Normally, liquid waste is injected at a depth of 10 to
16 cm. Injection within this range provides an aerated environment for the
waste and insures rapid drying. Major benefits of rapid drying are decreased
potential for transport of contaminants from the sludge to groundwater and
the ability to make repeated passes over the same area at shorter time
intervals.
The deflector outlet area opening can be changed by bolting plates of
various lengths across the rear of the deflector. In clayey soils with
thicker waste materials (5% solids or more), the plate is left off. However,
the plate must cover the entire back of the deflector when injecting thin
waste materials in sandy soils. Deflector plugging is not a problem when the
material is pumped to the deflectors under a small pressure (34 kPa), using a
trash pump (pass 3.8 cm diameter solids).
Two major problems were observed in testing the first machine: (a) it
was impossible to pull the portable tank through the field except under
nearly ideal conditions, and (b) the "turn around" time was too long and
only 2% of the total operating time was spent injecting.
Major modifications of the above system were incorporated into sub-
surface injectors used to dispose municipal sewage sludge (Boulder machine)
and liquid dairy manure (Fort Collins machine). The units are shown in
Figures 3 and 4.
Material is supplied continuously through an underground pipeline which
is connected to a 200-meter flexible hose which, in turn, is connected to the
injector. A pump, located at the source or storage facility, delivers the
material to the injector. This eliminates the need to pull heavy portable
tanks through the field and provides continuous operation of the injector
until the supply is exhausted.
The Fort Collins machine has five injector sweeps with a 7.6 cm supply
hose. It is capable of injecting at rates up to 1,500 liters per minute
over a 230 cm width. The 34 kW wheel-type tractor is capable of pulling the
unit and hose in good weather at 2.4 km/hr. In moderately severe weather,
the speed must be increased due to the torque characteristics of the tractor
engine.
The Boulder machine consists of seven injector sweeps with a 11.4 cm
supply hose. It is capable of injecting at rates up to 3,000 liters per
minute over 305 cm width. A 31 kW crawler tractor has sufficient power to
pull the unit at approximately 1.6 km/hr. Speeds as low as 0.8 km/hr can be
used in good soil conditions. The tractor is equipped with wide tracks
(84 cm) to provide flotation in adverse weather. This unit is used regularly
in mud and snow; however, it will not operate when the frost depth is greater
than 5 cm.
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Figure 3. Boulder subsurface injector.
Figure 4. Fort Collins subsurface injector,
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Specifications and approximate sizes for the equipment are given in
Tables 1 and 2.
TABLE 1. SEVEN SWEEP INJECTOR SPECIFICATIONS
Operating speed
Capacity per sweep
Operating depth
Field efficiency
Tractor power required
Wheel type
Crawler type
Capacity
Maximum area covered per
hose attachment
Pressure required at
hose attachment
Solids content
Frequency of injection
0.8 to 2.4 km/hr
230 to 450 liters/min
7.6 to 20 cm
87 percent
34 to 90 kW
30 to 45 kW
187,000 to 748,000 liters/hectare
7.49 hectares
400 kPa
6 percent (nominal)
2 to 7 days
TABLE 2. INJECTOR SIZE RANGE
Hose
diameter ,
cm
7.6
10.1
11.4
12.7
Flow,
liter/min
1,500
3,000
3,800
5,300
Full
hose weight,
kg/m
4.6
8.0
10.3
12.8
Number
of sweeps
5
7
9 or 11
13
Width,
m
2.27
3.20
5.03
5.94
10
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Sweeps on the Fort Collins machine were replaced with chisel points for
use in frozen ground. The revised machine is shown in Figure 5 and an injec-
tor is shown in Figure 6. Note that the deflector was replaced by a straight
tube. With changes, it was possible to inject with the ground frozen to a
depth of 10 cm. However, the waste material was not completely covered (it
was estimated that between 60 and 70% coverage was achieved) and only two
passes could be made on a given area. The surface was left in a rough con-
dition with large pieces of frozen soil in random positions. This surface
condition should decrease the potential for runoff pollution.
The modified injector was also evaluated for use with septic tank wastes
in a high-mountain community (Summit County, Colorado). In these tests, the
coverage was essentially 100%; however, there were operational problems due
to large rocks in the injection field. Replacement of the chisel points with
narrow (8 cm wide) high-lift sweeps eliminated most of these problems.
Sweeps have a tendency to move or slide over and around rocks, whereas
chisel points tend to catch on them.
The injector is hitched to the crawler tractor by a parallel bar linkage.
This hitch holds the injector level with respect to the tractor at all oper-
ating depths and as the injector is raised and lowered, During normal opera-
tion, the injection depth is controlled by gauge wheels, However, in adverse
weather or field conditions, it is sometimes necessary to support the injec-
tor from the tractor. Both modes of operation are possible, using hydraulic
controls on the tractor. The standard agricultural three-point hitch is used
for attaching the injector to wheel-type tractors.
Turning the machine around while pulling the hose requires some operator
skill. An experienced operator can turn in 30 to 45 seconds and can inject
over 95% of the time the injector is in the field. The major difficulty in
turning is that the operator must perform a series of relatively precise move-
ments with the tractor to form a loop in the hose. Without first forming a
loop, it is impossible to make a turn. A hydraulically activated plug valve,
controlled from the tractor, is used to shut off the flow of manure when
turning or moving across the field with the injector out of the ground.
Maintenance of the injection system is relatively simple. Experience
indicates that the injector sweeps may have to be replaced twice during the
first year of operation at a new site. Annual replacement thereafter is
usually sufficient. It is necessary to relocate the hose coupling at the
machine every three to four months. This is accomplished by cutting off
about 18 inches of the hose and reinstalling the coupling, In more than
three years of operations, this is the only service required on the hose.
No wear has been detected.
During cold weather, precautions must be taken to prevent liquid from
freezing in the hose. The normal procedures are to purge the delivery system
and hose with air or to drain the hose by gravity. A three-inch hose can be
emptied by loading it on a transport reel. Reel units are commercially
available and are also convenient for transporting the hose or for storage.
Reel units for hoses larger than three inches in diameter can be equipped
with air pumps for purging the hose.
11
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Figure 5. Fort Collins subsurface injector adapted
for use in frozen ground.
Figure 6. Injector for frozen ground.
12
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SECTION IV
SITE DESCRIPTION AND EXPERIMENTAL PROCEDURES
APPLICATION SITE DESCRIPTION
The manure injection site was located on the Duane Fisher farm, approxi-
mately 1/2 mile north of Timnath, Colorado, and 5 miles east of Fort Collins,
Colorado. Soils at the 1.05 ha site consist of approximately 45 cm of loam
and sandy loam overlaying alluvial sands and gravels. The soil pH is 7.6.
The normal water table depth ranges from 1.5 to 2m during the period
from September to May or early June. However, during the irrigation season
(June through September), the water table depth ranges from 0.5 to 1m below
the soil surface.
The site layout is shown in Figure 7. Plots 1 and 2, (0.19 ha) were
operated together as were plots 3 and 4 (0.3 ha). The remainder of the site
was used as a control and received no manure. Groundwater equielevation
lines (March 1975) are also shown in Figure 7-
Manure was pumped from a 34,000-liter holding tank to the application
site through 90 m of buried 10 cm PVC pipe. The 200-meter flexible hose was
attached at the pipe outlet indicated in Figure 7. A 10 cm portable centri-
fugal pump, located near the holding tank, was used to move the manure
through the underground pipe, flexible hose and subsurface injector. Valves
at the pump were arranged to recirculate manure back to the tank to agitate
the liquid manure.
Silage corn and sugar beets were raised on the site prior to its use for
this research. Both liquid and feedlot manure were applied to the site but
no accurate records were available.
MANURE APPLICATION
Manure was injected on all plots, starting in September 1974. Approxi-
mately 95,000 liters were applied each month, in three applications per month.
Through April 1975, plots 1 and 2 received a total dry solids loading of
19,800 kg/ha and plots 3 and 4 received 10,200 kg/ha.
For six weeks during January and February 1975, manure was spread on the
ground surface, due to frozen ground, rather than being injected. The fol-
lowing year manure was injected on a regular basis and throughout the winter
using the modified injector described previously. No surface runoff was
observed in either case.
13
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Figure 7. Manure injection site.
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Corn was grown on plots 1 and 2 from June through September 1975. From
May through September, manure was injected in plots 3 and 4, increasing the
total dry solids applied by 18,000 kg/ha to a total of 28,200 kg/ha. After
the corn was removed in September, manure was injected on all plots through
March 1976, increasing the total dry solids loading by 13,800 kg/ha. The
loadings are summarized in Table 3.
SOIL AND GROUNDWATER SAMPLING
Soil samples were collected with a manual soil probe or a Giddings Rig
Core Sampler. Seven to 10 cores were collected from each plot, the cores
were divided by depth, and each set of depth samples were composited.
Well locations are indicated in Figure 7. Well 2 was regarded as being
least affected by the manure application and well 7 was regarded as the most
likely affected. Groundwater samples were collected from the wells with a
portable pump. The bottom 60 cm of the 10 cm PVC well lining pipe was
perforated to allow entry of water.
VACUUM EXTRACTORS
Soil water leaching from the manure application site is diluted when it
reaches the groundwater. The degree of dilution depends upon the thickness
of the aquifer, groundwater flow rate, and rate of percolation. Therefore,
it is difficult to measure leachate quality and nearly impossible to estimate
the amounts of contaminants leached by sampling groundwater.
Consequently, percolating leachate should be sampled before it reaches
the groundwater. Also, it would be advantageous to collect quantitative
samples of the leachate in order to determine total amounts of pollutants
entering the groundwater system.
Soil water above the groundwater table normally exists at less than
atmospheric pressures. Precipitation or leachate from sludge will percolate
downward through the soil at negative gauge pressures ranging up to 25 cm of
mercury. Thus, ordinary piezometers and observation wells used to sample
groundwater are useless above the water table because the pressure in the
soil is less than the pressure in the well (atmospheric) and water will not
flow into the well. A sampling device which can collect percolating soil
water under negative pressures (to 25 cm Hg) must be used.
Such a leachate vacuum extraction system was developed by Duke and Raise
(1973). In the system (Figure 8), hollow, saturated, porous, ceramic tubes
(30 cm long and 1.27 cm diameter) were placed near the bottom of a stainless
steel trough (152 cm long, 15 cm wide, and 18 cm deep). The ceramic tubes
had a bubbling pressure (vacuum at which desaturation begins) of one atmos-
phere. When a vacuum, larger than the negative pressure of the soil water
but smaller than the vacuum at which the ceramic desaturates, is applied to
the ceramic tubes, water will pass through the tube walls without allowing
the air to pass. Two rows of four tubes each, connected end-to-end with
plastic tubing, were placed on 2 cm of soil in the soil-filled trough.
15
-------
TABLE 3. SUMMARY OF MANURE LOADING.
Time Interval
£ September 1974-April 1975
May 1975-September 1975
September 1975-March 1976
Total applied
Plots
1
1
2
.65
.15
.80
Total
1 and
x 10
x 10
x 10
Loading ,
Jt/ha
2 Plots 3
6 0
1
6 1
6 3
.85 x
.50 x
.15 x
.50 x
and
10
10
10
10
4
6
6
6
6
Dry
Plots
19
13
33
Solids
1 and 2
,800
,800
,600
Loading, kg/ha
Plots
10
18
13
42
3 and 4
,200
,000
,800
,000
-------
SAMPLE
^NEXTRACTION
LINE
SOIL SURFACE
CANDLE
FLUSH
LINE
TO VACUUM
PUMP
CANDLE RESATURATION LINES
ACCESS WELL
CERAMIC
CANDLES
VACUUM
EXTRACTION
TROUGH
SAMPLE
COLLECTION
BOTTLE
\
Figure 8. Vacuum extractors.
-------
The depth of the trough was selected, based .on a theoretical analysis
(Corey, 1974), so that the soil-water pressure would adjust approximately to
the ambient soil-water pressure at the top of the trough. Thus, the extrac-
tor should not interfere significantly with normal soil-water flow and a
quantitative sample of leachate should be collected. The variation of soil-
water pressure upward from the ceramic tubes depends upon the soil properties
and flow rate. For the extraction troughs and vacuums used in this study and
the soil at the manure application site, the negative pressure at the top of
the trough should vary less than 10% from the ambient soil-water pressure.
This variation is smaller at higher soil-water percolation rates.
The extractor troughs and access wells were installed in a trench about
1 m below the soil surface. Plastic tubing was used to connect the ceramic
tubes to a sample collection bottle located in the bottom of a 30 cm diameter
lined access well. The trough and plastic tubing were sloped toward the well
so leachate would flow to the bottle by gravity. The trench was backfilled
with soil in about the same order as it was removed. Errors introduced by
this installation procedure may result in a small overestimate of the volume
of water leaching from the site (Trout et al., 1975),
Vacuum from the control system was applied to the sample collection
bottle and to the ceramic tubes through 0.64 cm polyflow tubing. The vacuum
control system consisted of a vacuum pump, tank pressure switch, and a mer-
cury manometer. The pressure switch regulated the vacuum in the tank between
38 and 50 cm Hg. This vacuum was reduced about 12 cm Hg at the extractors.
Three extractors were connected to each vacuum control unit.
The sample collection bottles were emptied through the polyflow extrac-
tion line at regular intervals, depending on precipitation and manure appli-
cation. Location of the vacuum extractors on the application site is
indicated in Figure 7-
ANALYSIS OF WATER AND PLANT TISSUE SAMPLES
Sample Preparation
Water samples were collected and stored in polyethlylene bottles. To
maximize stability in storage, samples were usually placed in bottles which
had previously been used for the same type of sample.
Aqueous samples were processed on the day received, when possible.
Groundwater samples were filtered through a membrane having 0.45 micron
pores. All samples were divided into two fractions. One fraction, preserved
with 1 m£ of concentrated sulfuric acid added to each liter of sample, was
used for nitrogen and boron determinations. The second fracoon, preserved
with 12 mJl of 0.5 molar nitric acid added to each liter of sample, was nor-
mally used for metal determinations. Sometimes metal determinations were
performed on the sulfuric acid preserved fraction. Phosphorus and chloride
were determined on either fraction, according to availability.
18
-------
Plant tissue samples were oven-dried for storage. Aliquots for analysis
were handpicked from the bulk sample because pulverization in a Wiley mill
was found to introduce metal contamination.
Digestion of manure and plant tissues were accomplished with nitric-
perchloric mixed acids. Dry ashing was carried out in a muffle furnace.
"Plasma" ashing (oxygen excited in a low pressure plasma discharge) was
applied when neither wet digestion nor dry ashing was acceptable for trace
metal analysis by atomic absorption.
Validation of the chemical analysis results produced was assured by
interspersing control among the unknown runs. The overall amount of control
approximated 5 to 10% of all runs. Examples of control runs are blanks,
blind duplicate determinations on unknowns, addition of known amounts of the
sought constituent to an unknown sample and then observing what percentage of
the known added material was recovered. Laboratory standards whose composi-
tion is known were also included as control. All procedures comply with or
are equivalent to recommendations published by the U.S. EPA (1972).
Determination Methods
Metals
Metals were determined by atomic absorption, using excitation either by
flame or, when higher sensitivity was required, by carbon rod atomization.
Chloride-
Chloride was determined by titration with silver nitrate, using either
potassium chromate indicator or a silver-silver chloride indicator electrode.
Nitrogen
Nitrogen determinations in all cases were based on final measurement as
ammonia, either by titration with sulfuric acid or by potentiometry, using an
ammonia-sensitive electrode. Samples were reduced, using Devarda alloy in
the presence of excess magnesium oxide while concurrently steam distilling
the reaction mixture to remove ammonia continuously. For ammonium nitrogen
determinations, ammonia either was separated by the same procedure, omitting
the Devarda alloy, or measured directly in a sample aliquot, using the
ammonia-sensitive electrode. Total Kjeldahl nitrogen determinations on
manure suspensions were carried out conventionally after establishing that
pretreatment with salicyclic acid and sodium thiosulfate was unnecessary.
Phosphorus
Phosphorus was determined colorimetrically as orthophosphate by the
vanadomolybdophosphoric acid method.
ANALYSIS OF SOIL SAMPLES
Determination Methods
Texture
Texture was estimated by feel.
19
-------
pH~
pH was measured on a saturated soil paste with a glass electrode pH
meter.
Electroconductivity
Electroconductivity was measured with a Solu-Bridge RD-26 and
conductivity cell on a saturation extract.
Organic Matter
Organic matter was determined colorimetrically on a sample prepared by
wet oxidation with potassium dichromate and concentrated sulfuric acid with
spontaneous heat of reaction.
Nitrate
Nitrogen samples were prepared by the phenoldisulfonic acid method and
levels were determined colorimetrically.
Available Phosphorus
Available phosphorus was extracted by the Olsen Bicarbonate Method and
determined by the ascorbic acid determination method.
Available Potassium
Available potassium was extracted with IN neutral ammonium acetate.
Levels were determined by flame photometry.
Total Nitrogen
Total nitrogen was determined by a regular Macro-Kjeldahl method,
MICROBIOLOGICAL AND OXYGEN DEMAND ANALYSIS METHODS
Determination Methods
All procedures used are described in Standard Methods for the Examination
of Waters and Wastewaters (AOHA, 1971)
Fecal Coliforms
Fecal coliforms in water samples were determined by the membrane filter
procedure. In soil samples, fecal coliforms and total coliforms were
determined by the Most Probable Number test.
BOD and COD--
BOD and COD were determined by methods 219 and 220 of the above listed
source.
20
-------
SECTION V
ENVIRONMENTAL MONITORING
INTRODUCTION
Evaluation of the effect of using the subsurface injection system
described previously for liquid manure requires measurement of changes which
occur at the application site. In this research, this involved measuring the
quantity and quality of manure applied and its effect on the soil, crops,
groundwater and leachate. Both biological and chemical analyses were used
in the evaluation.
Odors, insects and runoff were never observed at the application site.
This was due to the fact that the manure was thoroughly covered and mixed
with the soil. In general, the regular injection of manure from the holding
tank decreased odors and insects around the milking parlor and enhanced the
farmstead environment.
MANURE CHARACTERISTICS
Composition of the manure used in this research is shown in Table 4.
The manure consisted of flush water from the floor of a milking parlor reten-
tion pen and wash water from the milking parlor itself. The manure was col-
lected in a holding tank, located under the retention pen floor, for a period
of approximately 10 days before it was injected.
Manure samples were normally analyzed on a monthly basis; however, not
all determinations listed in Table 4 were made each time. The complete list,
except for the heavy metals, was made every three months. Due to the rela-
tively low heavy metals content of the manure, no further heavy metal
measurements were made and no heavy metals were monitored in the soils,
leachate, or groundwater at the application site.
PATHOGENS
Fecal coliforms (E. ooti) were used as an indication of the presence of
other enteric bacteria and pathogens because of their large numbers and ease
of measurement. The fecal coliform level in the liquid dairy manure was
approximately 2.8 x 10 per 100 m£, or approximately 2.8 x 10 fecal coli-
forms were added to the soil with each dry kilogram of manure.
Well samples were evaluated for presence of Salmonella and Pseudomonas.
Neither of these organisms was observed.
21
-------
TABLE 4. DAIRY MANURE ANALYSIS
Determination
Total Kjeldahl N
NH3 - N
Total P
K
Cl
Solids
TDS
Conductivity
*
Cd
*
Cu
*
Ni
*
Zn
Average Value
765 mg/Jl
618 mg/Jl
92 mg/Jl
1,076 mg/Jl
161 mg/Jl
1.2%
6,700 mg/Jl
5,700 ymhos/cm
0 . 8 ppm
33 ppm
<4.17 ppm
167 ppm
570 -
490 -
70 -
820 -
60 -
0.9 -
5,700 -
4,600 -
Range
880 mg/Jl
740 mg/Jl
140 mg/Jl
1,500 mg/£
235 mg/Jl
1.3%
8,700 mg/Jl
6,400 ymhos/cm
One determination
Results of soil core analysis, shown in Table 5, indicated that fecal
coliforms did not move readily through the soil when the water table was at a
depth greater than 1 m below the manure injection zone. This result agrees
with more extensive data reported by Trout et al. (1975) involving municipal
sewage sludge.
TABLE 5. COLIFOR11 ANALYSIS IN SOIL SAMPLES
Sample Depth, m
0.3
0.6
1.0
1.3
Total Coliforms/100 gm
160,000
22,000
1,700
230
Fecal Coliforms/100 gm
4,900
<200
<200
<30
*
Sampled April 1975
22
-------
Well water samples contained few fecal coliforms during the non-
Irrigation season. As shown in Table 6., .groundwater fecal coliform levels
in January and April were normally less than 10 per 100 mi. During this
period, the water table depth was from 1.5 to 2m below the manure injection
zone.
TABLE 6. BOD, COD AND FECAL COLIFORM IN WATER AND MANURE SAMPLES
Date
September 1974
January 1975
April 1975
June 1975
September 1975
January 1976
September 1976
Sample
W-2
W-3
W-7
W-9
Manure
W-2
W-5
W-7
W-2
W-5
W-7
L-3
Manure
W-2
W-5
W-7
L-3
L-8
W-2
W-7
W-2
W-7
Manure
W-2
W-7
BOD, mg/£
2.8
2.8
5.6
6,200
__
1.4
24.9
42.8
5.6
4.8
3.6
3.4
7.4
6,900
COD, mg/&
68.7
204.2
312.9
61.0
9,100
__
__
129.1
6.1
7.2
40.9
148.8
231.4
_
_
9,600
__-.
Fecal Coliforms/100 gm
3,000
2,400
>30,000
<10
2,800,000
8
30
<4
8
24
<4
2,500,000
12,000
30,000
6,000
2,400
6
4
2,800,000
26,000
42,000
Fecal coliform levels in the groundwater were considerably higher during
the irrigation season. Referring to Table 6, fecal coliform levels in wells
2 and 7 were both increased and the level in well 7 was normally greater than
the level in well 2 in June and September. There are two apparent reasons
23
-------
for this. First, the water table was often within 0,5 m of the ground
surface during this time and thus there was not sufficient unsaturated soil
to remove the fecal coliform prior to their reaching the groundwater. Second,
there were several home sewage disposal systems near the application site.
During the irrigation season, the groundwater may have picked up fecal coli-
form as it passed through these systems. Based on these results, it appears
that the water table must be at a depth of 1 m or more below the manure
injection zone to prevent contamination of the groundwater with fecal
coliforms.
OXYGEN DEMAND
The oxygen demand in a liquid sample, an indication of unstable organic
matter, is measured by the biochemical oxygen demand, BOD. The chemical
oxygen demand, COD, is a measure of the oxygen consuming capacity of
inorganic and organic matter present in the liquid.
Approximately 0.06 kg of BOD and 0.09 kg of COD were added to the soil
with each dry kilogram of manure. Referring to Table 6, virtually all of the
BOD and COD were removed in the soil. Also, comparison of September 1974
results with June 1975, indicated no increase in groundwater BOD or COD as a
result of manure application.
SALINITY
The electroconductivity of soil saturated extract is an indirect
measurement of total dissolved solids (TDS) or soluble salts. When the value
of 4.0 mmhos/cm is reached, TDS can be harmful to some plants (Richards,
1969). This high TDS condition can be created in arid climates when most of
the manure solution evaporates, leaving an accumulation of soluble salt ions
in the surface soil.
The soil electroconductivity is shown in Figure 9 for plots 1 and 2 and
Figure 10 for plots 3 and 4. This soil has a relatively high electroconduc-
tivity at all times, probably due to the shallow water table.
Also, the groundwater has a high TDS, particularly in September at the
end of the irrigation season (refer to Tables 7, 8, and 9). The electro-
conductivity on non-injected plots ranged between 3.5 and 4.2.
Manure application increased the soil electroconductivity on all plots.
A heavy rain (approximately 2.5 inches) during the first week in June 1975,
reduced the electroconductivity on all plots and it was further reduced on
plots 1 and 2 by irrigation. After the irrigation season, the electroconduc-
tivity increased until crops were planted and irrigation waters were applied
the following year.
Leachate TDS was always very high, as shown in Table 7. However, very
little of the applied water (less than 5%) reached the extractor level during
the non-irrigation season. Thus, it had little effect on the groundwater.
24
-------
10
S3
in
8
b
|
o
8
QC
b
0 -0.3m
0.3m-0.6m
0.6m-Im
Sept. Jan. May Sept. Jan.
Figure 9. Soil electroconductivity on plots 1 and 2.
May
Sept.
-------
10
0-0.3m Depth
10
E
u
V.
V)
o
£
E
8
o
o
o
o
8
ui
Sept.
Jan.
May
Sept.
Jan.
May
Sept
Figure 10. Soil electroconductivity on plots 3 and 4.
-------
TABLE 7. VACUUM EXTRACTOR SAMPLE ANALYSIS
Date
Oct. 1974
Jan. 1975
Mar. 1975
May 1975
Sept. 1975
Oct. 1975
Jan. 1976
Sample
LI
L2
L3
L4
L5
L6
L7
L8
L9
LI
L5
L9
L3
L3
L5
L7
LI
L3
L5
L5
L6
L6
L7
L7
L9
LI
L4
L8
L9
LI
L4
L5
LI
L3
L9
TKN
mg/A
2
5
11
4
5
10
11
11
2
4
8
3
4.6
11
29
28
28
37
30
42
22
14
1.2
12
9.1
8.0
3.4
14
0.69
2.9
0.82
N03-N
1.8
1.9
3.6
2.6
10.7
28.7
27.8
27.9
31.2
22.4
41.7
21.8
13.6
1.0
11.4
9.1
7.9
3.3
13.7
0.47
2.6
0.54
mg/H
1.2
0.78
0.63
0.07
0.09
0.34
0.20
0.12
0.38
0.24
1.1
0.11
1.0
0.2
1.0
0.76
1.5
0.6
K
mg/fc
4.7
7.7
7.2
2.9
2.5
5.3
3.7
5.9
3.6
25
39
56
45
63
24
27
49
47
29
32
37
41
30
35
25
46
32
40
45
53
49
Cl
mg/H
145
130
205
65
110
65
120
45
95
84
63
91
125
75
190
155
245
90
90
155
150
185
180
330
155
175
295
170
155
175
290
150
270
130
IDS
mg/i
7,300
8,000
8,200
6,500
5,200
5,500
8,400
5,100
6,400
7,600
6,000
7,000
7,500
3,900
7,000
5,300
7,300
3,900
4,200
7,000
6,900
4,900
5,100
6,300
__
(continued)
27
-------
TABLE 7 (continued).
Date
Apr. 1976
Sept. 1976
Sample
LI
L3
L5
L9
LI
L2
L3
L5
L9
TKN N03-N
mg/Ji, mg/fc
14
23
9
17
4.5
8
6.7
9.4
4.6
P04-P K Cl
mg/A mg/£ mg/£
135
185
230
165
192
163
126
TDS
mg/&
5,300
7,300
3,900
6,900
6,100
3,800
6,800
TABLE 8. INITIAL GROUNDWATER QUALITY (Sept. 1974)
Determination
Average Value
Range
Total Kjeldahl N
N03-N
P04-P
K
Cl
TDS
10
8.6
3.5
12
46
4,800
mg/Jt,
mg/£
mg/fc
mg/£
mg/£
mg/Jl
6
0.1 -
1
2.4 -
30 -
3,900 -
16
5.7
7
31
80
6,500
mg/Jl
mg/Jl
mg/A
mg/Jl
mg/fc
mg/fc
Average of samples taken from all nine wells,
Groundwater. TDS, as shown in Tables 8 and 9, tended to vary with irri-
gation. TDS values were higher in August and September and lower from
January through June. Note, however, that the groundwater TDS was always
greater than 2,000 mg/£, which probably accounts for the high soil electro-
conductivity at the site. It was not possible to determine the rate of move-
ment of leachate from the site to the groundwater during the irrigation
season, due to the high groundwater table. However, comparison of TDS values
for wells 2 and 7 indicates that manure application had little effect on the
groundwater TDS.
28
-------
TABLE 9. ANALYSIS OF GROUNDWATER SAMPLES
Date
Jan.
Mar.
Apr.
May
June
July
Aug.
Oct.
Jan.
Apr.
Sept
1975
1975
1975
1975
1975
1975
1975
1975
1976
1976
. 1976
Sample
W-2
W-7
W-2
W-7
W-2
W-5
W-7
W-2
W-5
W-7
W-2
W-5
W-7
W-2
W-7
W-2
W-5
W-7
W-2
W-7
W-2
W-7
W-2
W-7
W-2
W-7
TKN
mg/Jl
6.9
10
8
7.3
9.6
12
9.4
11
8
8
12
8.6
8.8
11
11
5.6
19
7.9
15
6.9
7.7
7.8
8.7
9.4
9.1
7.4
NO -N
ml/a
6.6
9.8
7.6
7.1
8.4
11.9
9.3
__
__
6
7
8.8
7.4
PO -P
rag/S,
0.2
0.6
0.04
0.05
0.05
0.06
0.04
0.05
0.03
0.03
0.02
0.03
__
0.1
0.1
0.35
__
0.07
0.06
K
mg/a
5
9
7
4
5
10
5
4
8
4
4
8
4
__
3
8
8
6
7
4
6
__
5
4
Cl
mg/a
25
30
25
30
25
30
25
30
30
30
30
__
90
150
60
__
45
30
IDS
mg/a
2,000
2,100
2,200
2,000
2,000
2,400
2,100
2,200
2,200
2,200
2,200
2,200
2,100
2,200
2,200
4,100
4,900
4,600
4,700
3,400
2,100
1,700
1,900
2,000
4,300
4,100
It is possible to create harmful salt accumulations in manure-amended
soils under semiarid conditions which would require addition of water to
leach the salts to-lower levels. Such procedures may require good management
and close observation of the nitrate concentration in the leachate to prevent
contamination of the groundwater.
29
-------
LEACHATE AND GROUNDWATER ANALYSIS
Results of chemical analysis of soil leachate and groundwater samples
are shown in Tables 7, 8 and 9. Note that most of the total nitrogen is in
the nitrate form at the extractor level (1 m) and in the groundwater. IDS
values are high in the leachate as expected, due to the soil salinity and
high TDS of the manure.
It was not possible to reliably estimate the average rate of leachate
movement from the injection zone, due to the small quantity of water which
moved down. On the basis of the available data, less than 5% of the total
applied water (manure and precipitation) became deep seepage during the
period from September to May. During the irrigation season when more water
was applied, the groundwater was above the extractors, which prevented their
use except for groundwater sampling.
The nitrogen (and nitrate) concentration in the leachate tended to
increase in May. This was probably due to a small amount of precipitation
received in early April.
Comparison of values listed in Tables 8 and 9 indicates that the ground
water moving under the site was not degraded by leachate from the site.
Smith et al. (1977) proposed use of the following equation for
predicting the eventual well mixed groundwater contaminant concentration
due to land application of waste materials;
QL
C = -r^ (C_ - C ) + C
g Q L ° °
where: C = groundwater concentration after complete mixing
O
C = background concentration of groundwater
C- = leachate concentration
Q = rate of flow of groundwater
Q = rate of flow of leachate into the groundwater
L
Assuming QL/Qj is 0.01, a typical value for a similar application site,
the difference between the initial groundwater contaminant concentration and
leachate concentration would have to be greater than 100 mg/Jl. Because of
the variation in background concentrations, as shown in Table 8, a difference
as small as 1 mg/A would be difficult to detect. Thus, the application of
manure to this site had little or no effect on groundwater quality, except
as noted elsewhere in this report.
30
-------
Most of the total applied nitrogen is either used in plant growth,
denitrified, or remains in the upper soil layer. Since most of the applied
nitrogen was in the ammonia form, it was probably held in the soil and
mineralized slowly. However, this required further study because, although
nitrogen is an asset to agricultural lands, it can also be a dangerous con-
taminant in drinking water. The maximum level of nitrate nitrogen recom-
mended in drinking water is 10 mg/«, (U.S. EPA, 1971b) . Organic and ammonium
nitrogen in the soil, unless volatilized or used by plants, will be miner-
alized and nitrified to nitrate nitrogen. Nitrate ions are highly mobile in
the soil, and unless denitrified or taken up by plants, will move with perco-
lating water to the groundwater. As discussed by Hinesly et al. (1971),
nitrogen is the first limiting factor when municipal sludge is applied to
agricultural lands.
SOIL ANALYSIS AND CROP YIELDS
Effects of applying liquid manure to the site soils are illustrated in
Table 10. Organic matter, nitrate, phosphorus and potassium were increased
in the top 0.3 cm of the soil, due to the application of liquid manure.
Based on the average manure composition, a total of 57 kg of K was
placed on the site. Assuming all of this remained in the top 0.3 cm of soil,
the K level should have been increased by approximately 600 ppm. The K level
was increased by approximately 400 ppm, a reasonable comparison, in view of
the increased K concentration in the leachate, as shown in Table 10. A simi-
lar calculation indicates that the increased organic matter content of the
soil compares favorably with the measured value. The P level should have
increased by approximately 60 ppm. In this case, some results listed in
Table 10 indicate an increase but they are generally inconclusive. Recall
that the P concentration in the leachate was very low. However, it appears
that most of the organic matter, P and K added to the soil were retained in
the upper 0.3 m.
Most of the nitrogen in the manure is in the form of NH» (see Table 4).
Ammonia is mineralized to nitrate, N03, which is more readily utilized by
plants. A mass balance for nitrogen is difficult because many values must be
assumed (Trout et al., 1975). Results in Table 10 show that more nitrate
was available for plant growth after manure application. This is also
reflected in the increased yields for 1976 shown in Table 11, and increased
nitrogen in plant leaves and grain shown in Table 12.
The greater yield in 1976 as compared to 1975 was also due in part to
improved germination. Planting was delayed in 1975, due to the high soil
salinity. When the corn was planted in June, germination was reduced, as
compared to the untreated area. In 1976, the same germination rate was
observed in all areas. No manure was applied after March 1976. The corn was
planted earlier and was irrigated prior to emerging. All of these factors
probably contributed to the increased germination and yield in 1976.
31
-------
TABLE 10. SOIL ANALYSIS
to
Depth
Date Plot (m)
Sept. 1974 Composite 0.3
1, 2, 3 0.6
& 4 1.0
Apr. 1975 Composite 0.3
1 & 2 0.6
1.0
Sept. 1975 Composite 0.3
1 & 2 0.6
1.0
Apr. 1976 1 0.3
0.6
1.0
2 0.3
0.6
1.0
3 0.3
0.6
1.0
4 0.3
0.6
1.0
O.M.
pH (%)
7.6 1.8
7.6 0.9
7.6 0.5
7.8 2.0
7.9 1.2
8.0 0.6
2.1
1.0
0.7
2.5
1.4
0.7
2.4
1.5
0.6
2.0
0.8
0.6
2.0
0.8
0.5
N03-N
(ppm)
20
6
5
61
39
18
46
27
12
120
45
16
152
58
52
98
30
28
81
26
8
P
(ppm)
65
18
10
50
14
3
59
31
8
110
32
13
125
43
14
58
7
5
48
4
2
K
(ppm)
313
220
170
610
245
88
680
342
136
690
300
273
750
311
299
716
154
97
514
118
66
Texture
sandy loam
sandy clay loam
clay loam
sandy loam
sandy clay loam
clay loam
loam
clay loam
clay loam
sandy loam
sandy clay loam
clay loam
sandy loam
sandy clay loam
sandy loam
sandy loam
sandy clay loam
sandy loam
sandy loam
sandy loam
loamy sand
-------
TABLE 11. SILAGE CORN YIELD* AND GERMINATION DATA
Year
1975
1976
Plots 1 & 2
Germination Yield
% kg/ha
96.7 40,600
99.8 45,300
Plots 3 & 4
Germination Yield
% kg/ha
99.8 45,300
Untreated
Germination Yield
% kg/ha
99.9 44,400
98.8 45,000
*
Typical yield: 43,700 kg/ha (Source: 1974 Colorado Agricultural
Statistics, Colorado Department of Agriculture, Denver, Colorado)
Sweet corn was planted on a small area in plot 2 in 1975. Although it
was not used directly for research purposes, it had excellent flavor and was
a good morale booster for project personnel.
Heavy metals contents of the silage corn grown on the plots are shown
in Table 12. Values are all within normal ranges.
33
-------
TABLE 12. ANALYSIS OF CORN LEAF AND GRAIN SAMPLES
Sample
Typical
Typical
Leaf
Leaf
Grain
Leaf
Leaf
Grain
Cd Cu Ni Zn B
Date (ppm) (ppm) (ppm) (ppm) (ppm)
values -
values -
July
Sept.
Sept.
July
Sept.
Sept.
- leaf 0.0 - 5.0 6-20 0 - 5.5 20 - 70
- grain 0.1 - 1.0 4-10 0 - 5.0 20 - 100
1975 0.2 8 <1 48 0.16
1975 0.2 8 1 56
1975 0.3 12 1 68
1976
1976
1976 0.3 91 54
TKN
% dry weight
1.6
1.6
1.8
2.1
2.4
2.6
-------
SECTION VI
ECONOMIC COMPARISONS
In order to compare economics of continuous subsurface injection with
other land application systems, a comparison developed by the North Carolina
Agricultural Extension Service in Circular 568 (Kriz et al., 1973) will serve
as a basis. In this circular, six different dairy waste management systems
were compared. The information was based on handling manure from a 100-cow
herd with each animal weighing 640 kg (1,400 Ibs).
One of the systems analyzed by Kriz et al. (1973) utilized storage and
spreading of dairy manure in liquid form. This particular system will be
modified to incorporate the continuous subsurface injector, thus creating
a seventh system for comparative purposes.
The liquid manure system described by Kriz et al. (1973) had a storage
capacity which represented a 30-day clean-out interval. Also, a retention
pond was incorporated into the dairy layout to collect the milkhouse waste-
water and the storm runoff from a 152.4-mm (6-in.) rainfall (24-hour, 10-year
storm) . The estimated initial investment and annual costs of disposal for
the liquid manure system, as given in Circular 568, are presented in Table 13.
In Table 14, the items and costs are listed for a continuous subsurface
injection system under the same conditions used in Table 13 [100 cows at 640
kg (1,400 Ibs) each.]. The scraper, its required tractor use, storage tank,
agitator pump, and retention pond cost the same for both systems, but are not
necessarily the same equipment. A high efficiency pump would be required for
the injection system; however, this would not be as critical for the spreader
system.
With the continuous subsurface injector, it becomes feasible to inject
the runoff water from the retention pond rather than irrigating. For the
volumes being considered in this comparison (859 k£ or 226,000 gallons of
runoff), 9.4 hours of injector time is required for disposal. The same pump
used to empty the pit can be used for the retention pond, thus the need for
an electric pump, irrigation equipment, and electricity is eliminated when
the continuous subsurface injection system is used.
In this particular comparison, 171 k£ (45,000 gallons) per month are
being disposed, since the storage tank for the spreader system contains this
volume. Apparently, no provision has been made for dilution water. In this
case, only 22.5 hours are needed to continuously inject the 2,052 k&
(540,000 gallons) of waste produced during the year. The.total annual hours
35
-------
TABLE 13. ESTIMATED INITIAL INVESTMENT AND ANNUAL COSTS OF DISPOSAL FOR A LIQUID MANURE STORAGE
AND TANK SPREADING SYSTEM FOR A 100-COW, FREE-STALL DAIRY WITH A 30-DAY STORAGE PERIOD
(from Circular 568, North Carolina Agricultural Extension Service)
Item
Scraper, rear mounted
.Tractor, 37-44 kW for scraping
Storage tank
Agitator pump
Tractor, 45-59 kW for agitating
and pumping
Spreader, liquid manure
Tractor, 67-74 kW for hauling
and spreading
Retention pond
Pump, 1.5 kW, 76 liters/min
(20 gpm)
Irrigation equipment
Electricity
Labor
Total
Initial
Investment
$ 300
3,900
1,900
2,100
150
500
1,215
$ 10,065
Estimated Cost
Ownership
Cost Factor Hours
0.18*
. 280
0.12^
0.27f
45
0.23**
. 105
0.12T
j.
0.27*
0.19+t
188
440
Hourly
Rate
$ 2.26
2.90
3.52
0.06
2.50
Annual
$ 54
633
468
513
131
438
370
18
135
231
11
1,100
$ 4,147
8 years of life; 7% interest on Jg initial cost; repairs, 1% of initial cost; taxes and insurance, 1%
, of initial,4cost
15 years of life, 7% interest on % initial cost; repairs, 0.5% of initial cost; taxes and insurance,
... 1% of inital cost
^6 years of life; 7% interest on % initial cost; repairs, 6% of initial cost; taxes and insurance,
1% of initial cost
6 years of life; 7% interest on \ initial cost; repairs, 2% of initial cost; taxes and insurance,
t 1% of initial cost
8 years of life; 7% interest on h initial cost; repairs, 2% of initial cost; taxes and insurance,
1% of initial cost
-------
TABLE 14. ESTIMATED INITIAL INVESTMENT AND ANNUAL COSTS OF DISPOSAL FOR A LIQUID MANURE STORAGE AND
CONTINUOUS SUBSURFACE INJECTION SYSTEM FOR A 100-COW, FREE-STALL DAIRY WITH A 30-DAY STORAGE PERIOD
u>
Estimated Cost
Item
Scraper, rear mounted
Tractor, 37-44 kW for scraping
Storage tank
Agitator pump
Tractor, 45-59 kW for agitating,
pumping, and injection (pit
and pond)
Installation of piping
Flexible hose
Subsurface injector
Tractor, 67-74 kW for injecting
Retention pond
Labor
Total
Initial
Investment
$ 300
3,900
1,900
2,480
1,300
1,000
150
$11,030
Ownership
Cost Factor
0.18*
t
0.12'
0.27f
0.12*
0.27?
0.23**
.
0.12
Hourly
Hours Rate
280 $2.26
44 2.90
32 3.52
324 2.50
Annual
$ 54
633
468
513
128
298
351
230
113
18
810
$3,616
8 years of life; 7% interest on Jg initial cost; repairs, 1% of initial cost; taxes and insurance,
|. 1% of initial cost
15 years of life; 7% interest on % initial cost; repairs, 0.5% of initial cost; taxes and insurance,
1% of initial cost
^6 years of life; 7% interest on % initial cost; repairs, 6% of initial cost; taxes and insurance,
k 1% of initial cost
6 years of life; 7% interest on % initial cost; repairs, 2% of initial cost; taxes and insurance,
1% of initial cost
-------
of injection for both the pit and pond is approximately 32 hours, compared to
150 hours for liquid spreading and 188 hours of pumping the retention pond in
the liquid spreading system. The estimated costs shown in Table 14 included
12 hours of agitation.
The major cost for the continuous subsurface injection system is the
piping. The cost was computed for 488 m (1,600 ft) of PVC pipe. Also, since
the subsurface injector being considered here is not currently available on
the market, a cost of $1,000 was estimated. Flexible hose for the system
would cost approximately $1,300.
The total initial investment for the continuous system is almost $1,000
higher than the spreader system. The major difference is reflected in the
annual costs where there is a $531 savings with the continuous subsurface
injector over the liquid spreader system. Since the initial cost of the con-
tinuous system is higher, the major annual cost savings result from the
reduced time needed to dispose of the wastes.
The comparisons presented in Tables 13 and 14 illustrate a liquid manure
system where a scraper is used to deposit the manure in a storage tank. The
major difference between the systems is the means of getting the manure to
the field and incorporation into the soil. How do these systems compare
economically to other means of collection and disposal? Returning to the
North Carolina Agricultural Extension Service Circular 568 and using the
results presented there (Table 15), it can be seen that the liquid spreader
system has the highest annual cost. The continuous subsurface injector
system has been inserted into Table 15 to illustrate how it compares economi-
cally. Rather than the liquid manure, 30-day storage system having the
highest annual cost with the batch spreader, the continuous injector method
of disposal lowers the cost of the liquid system and makes it more
competitive.
The continuous subsurface injector may make the last three systems
presented in Table 15 more economical if the irrigation component was
replaced with the injection system. Since the irrigation system is continu-
ous, the injector would not have as dramatic economic effects as it had with
the liquid spreader. However, it may have dramatic effects on the environ-
mental conditions of the disposal operation. Since the effluent is under-
ground, many problems associated with surface irrigation of wastewater would
be eliminated.
Along this same line, those methods that use surface disposal may
require an additional field operation in order to "plow down" the manure.
No attempt has been made to include this cost into the above^economic compari-
son. This cost would not be necessary with the continuous injection system.
Also, no attempt has been made to account for inflation between the time when
Kris et al. (1973) made their calculations and the time when the calculations
were done for this paper. Summer of 1974 estimates were used for the subsur-
face injector. If inflation had been accounted for, the liquid manure system
with continuous subsurface injection would be even more competitive economically.
38
-------
TABLE 15. ESTIMATED INITIAL INVESTMENT, ANNUAL COSTS AND LABOR REQUIREMENTS FOR
ALTERNATIVE WASTE MANAGEMENT SYSTEMS FOR A 100-COW, FREE-STALL DAIRY*
vO
Waste Management System
Direct spreading in solid form
Storage and spreading in solid form
Storage and spreading in liquid form
(30-day storage and liquid spreader)
Storage and injection in liquid form
(30-day storage and continuous
injection)
Lagoon and irrigation
Flush, storage tank, and irrigation
Flush, lagoon, and irrigation
Initial
Investment
$ 4,415
5,165
10,065
11,030
7,680
12,945
17,095
Annual
Ownership
Costs
$1,873
1,963
1,902
1,932
1,391
2,475
2,898
Annual
Labor
Requirements
(hrs)
504
504
440
324
325
223
213
Total
Annual
Cost
$3,206
3,326
4,147
3,616
2,924
3,501
3,982
t.
Data for all systems except the continuous injection system taken from Circular 568 of the North
Carolina Agricultural Extension Service.
Does not include tractor ownership costs.
-------
Thus, not only is the continuous subsurface injection system economi-
cally competitive and a tremendous labor saving concept, it also provides a
much better means of disposal from an environmental standpoint. Odors and
insects normally associated with manure disposal on land are greatly reduced
since the manure is covered by the soil at such a depth that rapid drying
occurs and aerobic conditions prevail. As a result, the environment is
greatly improved for the dairy farmer and his neighbors, and becomes much
more pleasing aesthetically.
40
-------
SECTION VII
APPLICATION EXAMPLE
Many dairies along the "Front Range" of Colorado and in other urbanizing
areas of the country are facing a difficult situation. The perishability of
milk and the need for market necessitate a location near cities, while the
environmental conflicts seem to be forcing them further away. A specific
example is the Colorado State University (CSU) Dairy located in Fort Collins.
The dairy was located in the late 1950fs. Its location was assumed to be far
enough from the city to cause few problems. Figure 11 very clearly illus-
trates the situation today. The dairy is surrounded by urbanization and is
facing a critical situation with regard to waste disposal.
Figure 11 illustrates how the continuous subsurface injection system
could be installed at the CSU Dairy. Manure from the dairy would be stored
in the manure pit. Before beginning the disposal operation, the slurry would
be prepared for pumping by developing a 5 to 8% solids content. This may or
may not require the addition of water, depending upon the collection system
(scraper or flush). From the pit, the manure would be pumped via an under-
ground pipe to a point in the center of a nearby field. At this point, a
flexible hose would be attached. The dairyman then injects the manure with a
continuous operation. The fields are rotated and when not used for injection,
are used for pasture, crops, etc.
From one hose connection, approximately 7.5 hectares (18.4 acres) can be
injected. Assuming a dairy herd of 100 cows at 640 kg (1,400 Ibs) each,
results in a yield of approximately 260 dry Mg (287 dry tons) of manure each
year (105 Ibs of manure/cow/day x 15% dry matter x 100 cows x 365 days/year *
2,000 Ibs/ton). If only one connection is used, the loading on the site is
35 dry Mg/ha/yr (15.6 dry tons/acre/year). If two hose connections are
installed, only 17.5 dry Mg/ha/yr (7.8 dry tons/acre/year) are applied.
Recommended rates for crop growth vary widely [22 Mg/ha/yr-66 Mg/ha/yr (10-30
tons/acre/year)], but around 22 Mg/ha/yr (10 dry tons/acre/year) is currently
accepted as a safe figure (Reed, 1969; Miner, 1971). Rates of 98 Mg/ha/yr
(48 dry tons/acre/year) have been used by Kansas State University to obtain
maximum corn yields (Shuyler et al., 1973). Salt accumulations become criti-
cal with some manures in this situation. However, with the 100-cow dairy
herd, one or two hose connections are easily within the safe range. (Two
connections may be more desirable so crops can be grown on the field not
being used for disposal.)
The continuous nature of the injection system shows its advantages when
the time and cost of disposal are computed. For the assumed herd above,
0.057 cubic meter (2 cubic feet) of manure at 85% water will be generated
41
-------
APARTMENTS
ro
ZONED
BUSINESS
CONDOMINIUMS
DISPOSAL
FIELD
#2
DISPOSAL
FIELD
IRRIGATED
CROPLAND
IRRIGATION
DITCH
COLORADO STATE UNIV.
DAIRY
UNDERGROUND
PIPE
MANURE
PIT
HIGH
SCHOOL
Figure 11.
HOUSING DEVELOPMENT
Colorado State University's Dairy location illustrating urbanizing nature of
surroundings and proposed layout of a continuous subsurface injection system.
-------
per cow per day (ASAE Standard No. R 345). To achieve a pumpable consistency
(95%), an additional 0.057 cubic meter (2 cubic feet) of water must be added
for a total of 0.114 cubic meter (4 cubic feet) per cow per day. This
amounts to 114 liters (30 gallons) of liquid manure per cow per day or 11.4
kA (3,000 gallons) per day for the herd. For the year this totals 4.16 M&
(1.095 x 10° gallons) which must be injected. For the one hose connection,
555 k£/ha/yr (59,500 gallons/acre/year) need to be injected, while for the
two hose connections, 278 kA/ha/yr (29,6000 gallons/acre/year) must be
inj ected.
Assuming a pumping rate of 1,420 Jl/min (400 gal/min) and an application
rate of 266 kH/hr/pass (28,000 gallons/acre/pass), the one hose connection
system would require a little over two passes per year. The two hose con-
nections would involve slightly over one pass per year. Pumping 1,420 £/min
(400 gal/min) and having 4.16 M£ (1.095 x 106 gallons) to be pumped and
injected at the same time, requires 45 hours per year, No time is involved
in transportation or filling a portable tank, Using a 3,040 liter (800 gal-
lon) capacity liquid spreader would require approximately 1,360 trips in one
year or an average of 3.7 trips per day. The continuous injection system
requires 7.5 minutes per day of actual injection. Assuming 30 minutes per
trip for the liquid spreader, the savings are readily apparent.
43
-------
SECTION VIII
REFERENCES CITED
1. American Public Health Association, AWWA and WPCF. 1971. Standard
Methods for the Examination of Water and Wastewater. 13th ed.
APHA, Washington, D. C.
2. Bernard, H., J. Denit, and D. Anderson. 1971. Effluent Discharge
Guidelines and Animal Waste Management Technology. Proc. Nat.
Symposium on Animal Waste Management, Warrenton, VA.
3. Corey, P. R. 1974. Soil Water Monitoring. Unpublished Report to
Department of Agricultural Engineering, Colorado State University,
Fort Collins, CO.
4. Duke, H. R., and H. R. Haise. 1973. Vacuum Extractors to Assess Deep
Percolation Losses and Chemical Constituents of Soil Water. Soil
Sci. Soc. of Am. Proc., Vol. 37, No. 6. pp. 963-964.
5. Gold, R. C., J. L. Smith, and R. D. Hall. 1973. Development of an
Organic Waste Slurry Injector. ASAE Paper No. 73-4529. American
Society of Agricultural Engineers, St. Joseph, MI 49085.
6. Hinesly, T. D., 0. C. Braids, and J. C. Molina. 1971. Agricultural
Benefits Resulting from the Use of Digested Sewage Sludges in Field
Crops. Interim Report to U.S. EPA. University of Illinois,
Urbana, IL.
7. Kriz, G. J., et al. 1973. Dairy Waste Management Alternatives. North
Carolina Agricultural Extension Service Circular 568, North Carolina
State University, Raleigh, NC. Sept.
8. Miner, J. R. (ed.). 1971. Farm Animal-Waste Management. Special
Report No. 67, North Central Regional Publication 206, Agricultural
and Home Economics Experiment Station, Iowa State University, Ames, IA.
9. Reed, C. H. 1969. Specifications for Equipment for Liquid Manure
Disposal by the Plow-Furrow-Cover Method, pp. 114-119. In
Animal Waste Management, Cornell University, Ithaca, NY.
10. Richards, L. A. (ed.). 1969. Diagnosis and Improvement of Saline and
Alkali Soils. Handbook #60. USDA, U.S. Salinity Laboratory,
U.S. Government Printing Office, Washington, D. C.
44
-------
11. Shuyler, L. R., et al. 1973. Environment Protecting Concepts of Beef
Cattle Feedlot Wastes Management. Report of Project No. 21 AOY-15,
National Environmental Research Center, EPA, Corvallis, OR. July.
12. Smith, J. L., D. B. McWhorter, and T. J. Trout. 1977. Mass Balance
Monitoring Strategies for Land Application of Wastewater Residuals.
Transactions of the American Society of Agricultural Engineers.
(in press)
13. Trout, T. J., J. L. Smith, and D. B. McWhorter. 1975. Environmental
Effects of Land Application of Digested Municipal Sewage Sludge.
Report submitted to City of Boulder, CO. Department of Agricultural
Engineering, Colorado State University, Fort Collins, CO.
14. U.S. EPA. 1971a. Demonstration and Development of Facilities for
Treatment and Ultimate Disposal of Cattle Feedlot Wastes. Interim
Report by Kansas State University to U.S. Environmental Protection
Agency.
15. U.S. EPA. 1971b. Manual for Evaluating Public Drinking Water Supplies.
U.S. EPA. Washington, D. C.
16. U.S. EPA. 1972. Handbook for Quality Control in Water and Wastewater
Laboratories, Analytical Quality Control Laboratory, National
Environmental Research Center, Cincinnati, OH.
17. Yeck, R. G., and P. E. Schleusener. 1971. Recycling of Animal Wastes.
Proc. Nat. Symposium on Animal Waste Management, Warrenton, VA.
45
-------
SECTION IX
LIST OF PUBLICATIONS
1. Smith, J. L., D. B. McWhorter, and R. C. Ward. 1975. On Land Disposal
of Liquid Organic Wastes Through Continuous Subsurface Injection.
Proc. 3rd International Symposium on Livestock Wastes1975. American
Society of Agricultural Engineers, St. Joseph, MI., pp. 606-610.
2. Ward, R. C., J. L. Smith, and D. B. McWhorter. 1975. Animal Waste
Management Through Continuous Subsurface Injection. Paper No. 75-4030,
1975 Annual Meeting of the American Society of Agricultural Engineers,
University of California, Davis, CA. June.
3. Downs, H. W., J. L. Smith, and D. B. McWhorter. 1975. Continuous
Subsurface Injection of Municipal Sewage Sludge. Paper 75-2530,
1975 Winter Meeting of the American Society of Agricultural Engineers,
Chicago, IL. Dec. 15-18.
4. Smith, J. L., and D. B. McWhorter. 1976. Continuous Subsruface
Injection of Liquid Organic Wastes, pp. 643-656. In Land as a Waste
Management Alternative. R. C. Loehr (ed.), Proc. of the 1976 Cornell
Agricultural Waste Management Conference. Ann Arbor Science Publishers
Inc., Ann Arbor, MI.
46
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-77-117
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
CONTINUOUS SUBSURFACE INJECTION OF LIQUID DAIRY MANURE
5. REPORT DATE
June 1977
issuing date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
J. L. Smith, D. B. McWhorter, and R. C. Ward
8. PERFORMING ORGANIZATION REPORT NO,
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Colorado State University
Fort Collins, Colorado 80523
10. PROGRAM ELEMENT NO.
1HB617
11. CONTRACT/GRANT NO.
S-802940
12. SPONSORING AGENCY NAME AND ADDRESS
Robert S. Kerr Environmental Research Lab. - Ada, OK
Office of Research and Development
U.S. Environmental Protection Agency
Ada, Oklahoma 74820
13. TYPE OF REPORT AND PERIOD COVERED
Final (l/74-12/76^>
14. SPONSORING AGENCY CODE
EPA/600/15
15. SUPPLEMENTARY NOTES
16. ABSTRACT
The research has involved the development and evaluation of an efficient, economical,
continuous subsurface injection machine. The application site was instrumented so
the quality of water percolating beneath the injection zone could be measured. Wells
located around the sites were used to monitor groundwater quality. Soil samples
were taken periodically to determine nutrients, salts, heavy metal concentrations,
and bacteria movement and survival.
Major environmental problems were increased soil salinity and movement of fecal
coliform to the groundwater. Both of these problems can be eliminated by proper
management and site selection.
Subsurface injection is economically feasible when compared with other methods of
land application. Although capital costs are greater for subsurface injection,
labor costs are significantly reduced. Other advantages of subsurface injection
are elimination of odors, insects, and visual pollution and minimization of runoff
pollution.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
COSATI Field/Group
Dairies; Fertilizers; Wastes: Injection;
Pollution; Groundwater; Runoff; Salinity
Continuous subsurface
injection machine;
Groundwater quality
monitoring; Soil
nutrients; Fecal coliform
02/C
18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (ThisReport)
UNCLASSIFIED
21. NO. OF PAGES
55
20. SECURITY CLASS (This page)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
47
GOVERNMENT PRINTING OFFICE: 1877-757-056/6457 Region No. 5-11
------- |