United States
Environmental Protection
Agency
Robert S. Kerr Environmental
Research Laboratory
Ada OK 74820
Research and Development
EPA-600/S2-81-151 Sept. 1981
Project Summary
Soil Filtration of Sewage
Effluent of a Rural Area
B. R. Sabey, K. A. Barbarick, and N. A. Evans
The effects of sprinkler-irrigated
municipal sewage effluent and of
surface tile drainage on a mountain
meadow were investigated in the
summers of 1977 and 1978. The
treatments consisted of combinations
of irrigations with effluent or ditch
water at the rate of 7.5 centimeters/
week (cm/week) and of drainage tiles
or natural drainage. Before applica-
tion, the effluent contained signifi-
cantly higher levels of some water
quality parameters than the ditch
water.
The drainage tiles were effective in
lowering the groundwater elevations
for about 85% and 10% of the season
in 1977 and 1978, respectively.
Higher plant concentrations of sodium
(Na) and manganese (Mn) in 1977and
plant yields and Mn concentration in
1978 were found in the plants har-
vested from the plots that were
irrigated with sewage effluent. The
influence of the effluent on ground-
water quality and soil characteristics
did not pose serious health or environ-
mental problems.
Another study to determine the
feasibility of adding sewage effluent
to mountain meadow land during
winter was initiated in 1977 at
Hayden, Colorado, near the summer
effluent application site. The latter
study was motivated by the possibility
of decreasing construction costs of
sewage treatment facilities.
It was determined that 7.5 cm/week
of effluent could be added to the plots
under an ice or snow cover if the soil
profile was not frozen prior to ice and
snow cover formation in the late fall
and early winter. The size of ridge and
furrow configuration did not influence
any of the biological and chemical
parameters measured in the study.
The winter soil filtration system was
effective in decreasing the concentra-
tions of some chemical constituents
including ammonium (NH4+) and
potassium (K+). as well as decreasing
biochemical oxygen demand (BOD),
chemical oxygen demand (COD), and
indicator organisms. The decrease in
indicator organism numbers was not
as great the second year of the study
as it was the first.
In general, the effluent distribution
system worked reasonably well even
in the winter as long as rapid drainage
of the pipes was provided at the
conclusion of the application period of
each day. The feasibility of adding
effluent to the land has been demon-
strated when weather conditions
provided adequate snow covers prior
to freezing of the soil profile.
This Project Summary was devel-
oped by EPA's Robert S. Kerr Envi-
ronmental Research Laboratory, Ada,
OK, to announce key findings of the
research project which is fully docu-
mented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
Summer Study
The waste products that society
produces will require disposal or
recycling techniques which minimize
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contamination of the environment.
Among these waste products are
sewage sludges and effluents. Every
municipality, regardless of size must
treat and dispose of, or utilize, its
sewage in some manner. Current
alternatives range from secondary
treatment involving anaerobic digestion,
trickling filtration, aerobic digestion,
lagooning, pohshing ponds, or combina-
tions thereof. Land application is being
considered in many areas as a possible
final treatment for effluent before it
reaches a stream. For large cities, the
more elaborate treatments may be more
practical for handling the large volume
of sewage; however, for small treatment
plants in rural areas, the possibility of
soil filtration as part of the treatment
process could be more practical. Bouwer
(1968)' claimed that the quality im-
provement obtained by soil percolation
is probably comparable to that obtained
by coagulation, sedimentation, carbon
adsorption, and disinfection.
'Bouwer, H. 1968. Returning wastes to the land, a
new role for agriculture. J. Soil & Water Cons.
23:164-168
Many studies have been conducted
utilizing land treatment for disposal or
recycling of municipal and industrial
effluents. The study conducted at
Hayden, Colorado was 'unique in two
ways. First, it was conducted at high
altitudes of the Rocky Mountain region.
Secondly, it involved application of
wastewater to mountain meadow type
of vegetatjon (see Table 1).
The effectiveness of land treatment
depends on the quality and application
rate of the sewage effluent and the soil
characteristics. Consequently, the
objectives of this research were:
1. To determine if the soil could effec-
tively remove the problematic sub-
stances from primary treated munic-
ipal effluent before the filtrate
entered streams, lakes, or ground-
water. The major concerns were:
a. Nitrogen (N) compounds such as
nitrates (NOa), ammonium (NH4),
and organ ic-N.
b. Phosphorus (P), potassium (K),
calcium (Ca), magnesium (Mg),
sodium (Na), iron (Fe), zinc (Zn),
copper (Cu), and manganese (Mn)
c. Biochemical oxygen demand
(BOD) and chemical oxygen
demand (COD).
d. Fecal and total coliform and fecal
streptococcus.
2. To follow the changes in soil proper-
ties created by sprinkler irrigation
with sewage effluent.
3. To investigate the benefits of provid-
ing drainage in a "soil filtration"
system.
4. To determine if the yields and quality
of hay produced by a mountain
meadow irrigated with sewage
effluent differed from those obtained
from irrigation with typical irrigation
water.
5. To determine the length of season
during which sprinkler irrigation was
feasible on mountain meadows at
the altitude and latitude of Hayden.
Winter Study
Application of sewage effluent to
mountain meadows during the summer
growing season appeared to be much
more feasible than during the winter
months where soils were more likely to
freeze to a considerable depth and
prohibit infiltration and permeability. If
the soil surface and profile could be
protected by the insulation of an ice
Table 1. Vegetation Species Found in the Mountain Meadow Used for Land
Treatment of Polishing Pond Effluent of Hayden, Colorado
Common Name
Scientific Name
Red clover
Orchard grass
Timothy
Bluegrass
Dandelions
White clover
Sweetclover
Alfalfa
Red fescue
Sedge-type grasses
Western wheatgrass
Trifolium pratense L
Dactylis glomerata L
Phleum pratense L
Poa pratensis L
Poa compressa L
Taraxcum offinciale L.
Trifolium repense L
Melilotus officinalis L.
Medicago saliva L.
Festuca rubra L
Carex spp. (Dill.) L.
Agropyron smithii L
sheet and/or a layer of snow as'
illustrated by Figure 1, it would be
possible to apply effluent by furrow
irrigation under the snow and ice and
still use the soil as a filtration system.
This would allow a municipality to
decrease the winter storage capacity
and thus make land application more
cost effective.
Although there have been many
studies on the effectiveness of land
application of sewage effluent in the
eastern, central, and southern parts of
the United States, few have been made
in the intermountain west. Only one
study on winter application of effluent at
higher altitudes was reported in the
literature. That study involved the
winter application of effluent from the
sewage treatment plant of a cheese
processing factory in Wyoming (Arm-
strong etal., 19782). No study was found
on the soil filtration treatment of
municipal sewage effluent during the
winter season.
^Armstrong, D.L., J. Barrelli, and R.D. Burman.
1978. Land application of wastewater for treatment
and disposal. The Thayne, Wyoming Experience.
Proceedings Rocky Mountain Region Meeting,
Amer. Soc. Agr. Eng., Denver, Colorado. February
ia
The objectives of the winter study
were as follows:
1. To determine if it were possible to
keep the soil profile unfrozen during
the winter by forming a sheet of ice
covered by snow over a ridge and
furrow formed surface.
2. To determine if an effluent applica-
tion rate of 7.5 cm/week could be
maintained throughout the winter
season.
3. To determine if the size of the ridges
and furrows influenced the ease or
difficulty of effluent application
under the snow and ice.
4. To determine to what degree the soil
filtration system of effluent treat-
ment would decrease the content of
several chemical and biological
constituents of the effluent.
Conclusions
The field study was used to compare
the effects of irrigation of the mountain
meadow with sewage effluent (SE) vs.
ditch water (DW) pumped from a nearby
stream and the presence of natural
drainage vs. drainage tiles. The meadow
was irrigated for about 20and 22 weeks
in the summers of 1977 and 1978,
respectively. The drainage tiles were I
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'.'.'.'.'.'.'.'.'.'.'. ' . ' . ' . ' . ' . ' .'.'.'
Figure 1. Cross section plqt A.
effective in lowering the groundwater
for about 85% of the application season
in 1977; however, the groundwater
elevations were lowered only about
10% of the season in 1978.
Only the N03-N levels in the irrigation
sources (prior to application) varied with
sampling date in 1977. All other chemi-
cal and biological parameters did not
significantly change between summer
samplings. The SE contained signifi-
cantly higher concentrations of most of
the chemical and biological constituents
than the DW used for irrigation. Data
illustrated that the chloride concentra-
tions in the soil solution, groundwater
and tiles in 1978 were increased by the
application of SE. Many of the param-
eters in the soil water samples from the
plots fluctuated with the time of
sampling.
Data reported in the project report
illustrated that in 1977 some of the
plant characteristics were significantly
affected by the major treatment factors.
A higher level of grasses was found in
the treatments with drainage tiles. The
type of drainage influenced some plant
quality parameters because of the
difference in the characteristics of
grasses and legumes and their ability to
absorb various nutrients and trace
metals. Sewage effluent caused in-
creases in the total uptake of some of
the plant nutrients and trace metals.
The addition of SE increased plant
concentrations of Na and Mn. Signifi-
cantly higher levels of Na and Mn in the
effluent as compared to the DW probably
caused these increases.
The major treatment factors did not
affect the plant distributions measured
in 1978. Two plant harvests were made
in the summer of 1978, and the time of
harvest had a highly significant effect
on a number of plant concentrations
and/or total uptake values. Proper
management of mountain meadows
can result in two cuttings with the
second harvest providing lower yields
than the first cutting. Data presented in
the project report showed that the
application of sewage effluent resulted
in increases in yield and the higher
yields resulted in higher amounts of
total uptake of some nutrients and
metals. Because of the higher Mn levels
in the effluent, the addition of sewage
effluent resulted in increases in plant
Mn concentration. The application of
ditch water caused increases in the
plant Fe concentrations. The reasons for
this effect of the ditch water on the Fe
concentrations may have been due to
the higher Fe levels in the ditch water.
Time of sampling as indicated by data
in the project report influenced the
levels of the exchangeable cations, total
metals, and available micronutrients in
the soil samples. The decrease in
exchangeable Mg was attributed to the
higher levels of Ca as compared to Mg in
the irrigation sources. The addition of
irrigation water could have accounted
for the changes in exchangeable cations.
For total metals and micronutrients,
changes between samplings could not
be totally attributed to additions from
the irrigation waters or losses from
plant uptake. Consequently, the reason
for the changes in these soil properties
were not known. The type of drainage
was found to influence some of the soil
chemical properties for samples from
different depths. Since the effect of type
of drainage was not consistently re-
flected in the plant data, the soil
differences were not considered impor-
tant. The application of sewage effluent
produced increases in surface soil
samples in the exchangeable Na,
bicarbonate (HCO3), extractable inor-
ganic P04, and exchangeable K. The
higher levels of Na, P, and K in the
sewage effluent as compared to the
ditch water probably caused the in-
creases in the surface soils.
Results from the field study indicated
that the application of sewage effluent
at the rate of 7.5 cm/week for two
irrigation seasons posed no serious
health or environmental problems.
Also, drainage tiles did lower the
groundwater levels for about 85% and
10% of the application season in 1977
and 1978, respectively. Leaching' of
problematic substances into the ground-
water or change in the soil properties
was found to be of little practical
concern. Changes in the level of various
N species in the soil were probably the
result of using intermittent rather than
flood irrigation. Irrigation with effluent
resulted in higher plant yields and total
uptake of,various plant nutrients than
were found with irrigation with the ditch
water. Therefore, application of the
effluent resulted in beneficial effects to
the hay crop in 1977 and 1978.
It was possible during the two winter
seasons of this study, to add 7.5
'cm/week of effluent due to the early
snow cover that fell on the plots keeping
the soil profile from freezing and thus
allowing infiltration into the soil to occur
below the snow layer. The time of
snowfall is weather-dependent and
varies from year to year. During years
when snowfalls and accumulates later,
an ice sheet on the ridges and furrows
could be developed by the use of a
plastic sheet, spread on top of the
ridges, upon which water would be
finely sprayed on the plastic during
freezing conditions. A thick sheet of ice
could result that would insulate the soil
against freezing until later snowfall
would cover the ice and provide more
insulation.
Although there were no apparent
chemical or biological differences in the
parameters measured, due to the two
sizes of ridges and furrows, both were
generally effective in improving the
quality of water before movement into
the river. The soil filtration system used
in this study for treatment of Hayden,
Colorado municipal sewage effluent
was effective with the exception of one
questionable area. There were relatively
high concentrations of some of the
indicator organisms that appeared in
the soil water at the lower sampling
depths during the second year of the
study. This aspect shoulti be pursued for
further verification.
Recommendations
Although this study has given some
useful and definitive information, the
application of municipal sewage effluent
from mountain communities (higher
altitudes) to mountain meadows should
be investigated under different soil
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conditions. Other soils may respond
differently than those used in this study.
Additionally, a study using an effluent
of lesser quality than that of this
investigation should be used on moun-
tain meadows under near similar
conditions to this study. The effluent
used on these plots did not stress the
system with the possible exception of
the indicator organisms. Further in-
vestigations on indicator organism
accumulation and movement should be
made.
The next step would be summer and
winter application of effluent to field
scale areas using the methods of this
study. It appears that under the proper
weather conditions (especially temper-
ature and timely snowfall) as existed at
this site during 1977-1978 and 1978-
1979, the system could be used suc-
cessfully.
B. R. Sabey, K. A, Barbarick. and N. A. Evans are with the Department of Agron-
omy and Water Resources Research Institute, Colorado State University, Fort
Col/ins, CO 80523.
Lowell E. Leach is the EPA Project Officer (see below).
The complete report, entitled "Soil Filtration of Sewage Effluent of a Rural Area,"
(Order No. PB 81-238 073; Cost: $11.00, subject to change) will be available
only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Robert S. Kerr Environmental Research Laboratory
U.S. Environmental Protection Agency
P.O. Box 1198
Ada, OK 74820
•A U S GOVERNMENT PRINTING OFFICE, 1981 — 757-012/7328
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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