EPA 903-9-75-017
LAND APPLICATION
OF
WASTEWATER
Sponsored by
U.S. Environmental Protection Agency, Region III
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EPA 903-9-75-017
LAND APPLICATION
OF
WASTEWATER
Environmental Protection Agency
Region V, Library
230 South Dearborn Street
Chicago, Illinois 6060H
Sponsored by
U.S. Environmental Protection Agency, Region HI
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LAND APPLICATION OF WASTEWATER
Proceedings of a Research Symposium Sponsored
by the
United States Environmental Protection Agency, Region III
John M. Clayton Hall
University of Delaware
Newark, Delaware
November 20-21, 1974
Published by the
United States Environmental Protection Agency, Region III
Daniel J. Snyder III, Regional Administrator
PROTECTION AGES**-
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LAND APPLICATION OF WASTEWATER
Table of Contents
Page
EPA Guidance and Policy on Land Treatment 1
John T. Rhett
Land Application Research at Robert S. Kerr Environmental Reaseach Laboratory 3
Richard E. Thomas and Curtis C. Harlin, Jr.
Land Application Practices and Design Criteria 13
Charles E. Pound and Ronald W. Crites
Public Health Aspects of Land Application of Wastewater Effluents 27
Charles A. Sorber
Educational and Informational Needs for Achieving Public Acceptance 35
John 0. Dunbar
Experiences at Penn State with Land Application 36
William E. Sapper
The Environmental and Sociological Impact of Recycling of Agricultural Waste by Land Use 53
Benjamin J. Reynolds
^ Experience with Land Application of Wastewater and State Regulations-The Pennypack
\ Watershed 59
j Graver H. Emrich
\>
N' Experience with Land Application of Wastewater and State Regulations—Pennypack Watershed,
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EPA Guidance and Policy on Land Treatment
by
John T. Rhett
Deputy Assistant Administrator
Office of Water Programs, EPA
Washington, D.C.
I am pleased to participate in this symposium on
land application of wastewater because of the impor-
tance of it's theme. It focuses on an area of technology
that has been with us for many decades but has
recently gained importance due to the awareness of
environmental issues.
It is encouraging to see state, county and municipal
engineers, consulting engineers, municipal officials,
members of university facilities and conservationist
groups here to become acquainted with the current
state of the act, recent technical advances and actual
field experience in disposal of municipal effluents.
I must commend Dan Snyder and his Region III
staff for initiating the planning and implementing the
2 day symposium. A very fine program has been put
together in an effort to provide Region III people
current information.
From my view, the concept of recycling as a conser-
vation practice, appealing as it may be, has been in
conflict with the throw-away philosophy of our society
in which planned obsolescence has become a way of
life. If we, as a society, have such a disregard for the
value of material things, how, can we convince people
that recycling of such an unappealing material such as
sewage is a valuable alternative. One of the ways is
through a symposium such as this which can
capitalize on what I sense is the beginning of a change
in national attitude. There is new concern for the en-
vironment; there is new concern for conservation of
energy; and there is a growing recognition that our
resources are finite. These are only a few of the trends
that combine at this point in time to make the task of
gaining public acceptance of this concept of utilization
of wastes as opposed to disposing of them.
Aside from posing my philosophical concerns, I see
my role as an EPA headquarters participant in this
symposium as providing you with an insight to EPA
policy and guidance.
The Water Pollution Control Act Amendments of
1972 gives us a firm base from which to work and to
encourage land treatment. Title II of the act entitled
"grants for construction of treatment works" states
that "waste treatment management plans and prac-
tices shall provide for the application of the "best prac-
ticable waste treatment" technology before any dis-
charge into receiving waters, including reclaiming and
recycling of water and confined disposal of pollutants
so they will not migrate to cause water or other en-
vironmental pollution and shall provide for considera-
tion of advanced waste treatment technique," Title II
further states "the administrator shall encourage
waste treatment management which results in the
construction of revenue producing facilities for (1) the
recycling of potential sewage pollutants through the
production of agriculture, silva culture, or aquaculture
products or any combination thereof; (2) the com-
bined and contained disposal of pollutants not recy-
cled; (3) the reclamation of wastewater; and (4) the
ultimate disposal of sludge in a manner that will not
result in environmental hazards." The act goes on to
state "the administrator shall encourage waste treat-
ment management, which results in integrating
facilities to treat, dispose of, or utilize other industrial
wastes." Section 208 of Title II provides for the
development of area wide waste treatment manage-
ment plans and requires that such plan will provide
for any requirements for the acquisition of Land for
treatment purposes.
Section 403 of the act instructs the administrator
among other things to develop other possible locations
and methods of disposal or recycling of pollutants, in-
cluding land base alternatives.
Using these sections of the act as our guidance we, I
feel, have responded thru promulgating various
regulations, guidance documents and technical
bulletins that include land treatment as an integral
part. I would like to develop our guidance and direc-
tion by looking briefly at these documents and ex-
amining our current activities.
The document entitled "Alternative Waste Man-
agement Techniques for Best Practicable Waste
Treatment" was proposed for public comment in
March 1974. Comments have been received, revisions
will be made and it is anticipated the final version will
appear in the Federal Register prior to January 1975.
The document identifies the currently known
techniques for meeting the BPT requirements. A sub-
stantial portion of the document contains information
on land application and treatment techniques.
The choice of which alternative to adopt is left to
each municipality or regional sanitary district. If it
receives federal funds, however, it must be guided by
the agency's cost effectivenss regulations. I will add
that in these cost effectiveness regulations it specifical-
ly states that "all feasible alternative waste manage-
ment systems shall be identified. These alternatives
should include. . . .systems using land or surface dis-
posal. .".
Once one alternative is selected, it must comply
with certain additional requirements. Any land
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application or land utilization techniques must, in
order to qualify for federal funding, comply with
criteria designed to protect ground waters. These
criteria are intended to ensure that ground water
resources remain suitable for drinking water purposes.
The ground waters in the zone of saturation resulting
from land or surface disposal must meet the chemical
and pesticide level in the EPA public drinking water
criteria "Manual for Evaluating Public Drinking
Water." Other criteria have been developed but will
not be discussed for brevity.
With the anticipation of a large number of construc-
tion grant applications for land treatment systems be-
ing forwarded to the regional offices, as a result of the
Act, the technical bulletin "Evaluation of Land Ap-
plication Systems" was developed. It provides infor-
mation and program guidance to EPA regional offices for
analyzing and evaluating municipal applications for
federal grant for the construction of publically owned
treatment works using land application methods. It
also provides information and assistance to other
federal agencies, to interstate organizations, to state
water pollution control agencies, to the wastewater in-
dustry and to consultants and designers of land
application systems.
An evaluation checklist and background informa-
tion are provided, and procedures are given for
evaluating alternatives dealing with crop irrigation,
infiltration percolations, overland flow or com-
binations of these systems. Systems involving injection
wells, sealed evaporation ponds, or septic tank leach
fields for wastewater disposal are exluded.
Another document is being prepared for EPA on
costs of land application systems. This will provide
means and information for determining costs for land
treatment systems so they can be compared with other
systems on the basis of cost effectiveness. Cost com-
ponents, land requirements, and cost curves will be
developed for two stages of planning, preliminary and
detailed, for each major type of land treatment system
(irrigation, overland flow and infiltration-percolation.
Examples of cost calculation will also be included.
When completed, this document along with the
technical bulletin on evaluation procedures will give, I
feel, the regional offices adequate technical informa-
tion for a complete and thorough review of proposed
land treatment projects.
In order to emphasize that land treatment should be
given full and adequate consideration, a memoran-
dum was sent to each regional administrator from
John Quarles, Deputy Administrator, EPA. This
memorandum requested that the regional review of
application for construction of publically owned treat-
ment works require that land application be con-
sidered as an alternative waste management system.
The instructions to the regional administrators also
indicated that if it can be demonstrated that land
treatment is the most cost effective alternative, is con-
sistent with the environmental assessment, and in
other aspects satisfies applicable tests, the region will
insist that land treatment be used in lieu of other
systems of waste management.
I think the guidance is clear and straight forward. It
will be up to the regions to insure that adequate treat-
ment is given to land application or land utilization
techniques and it will be up to the design engineers to
include the land treatment alternative in all projects
proposed to be federally funded.
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Land Application Research at Robert S. Kerr
Environmental Research Laboratory
by
Richard E. Thomas and Curtis C. Harlin, Jr.
Water Quality Control Branch
Robert S. Kerr Environmental Research Laboratory
Ada, Oklahoma
INTRODUCTION
The Water Quality Control Branch (WQCB) of the
Robert S. Kerr Environmental Research Laboratory
(RSKERL) has been assigned Environmental Protec-
tion Agency (EPA) responsibility for research to
utilize agriculture, silviculture, or aquaculture proj-
ects for management of municipal wastewaters. The
major focus of this integrated research program is the
development of a reliable data base which establishes
the cans and cannots of these approaches with respect
to the goals of the Water Pollution Control Act of 1972
(PL 92-500). The transition from strictly land applica-
tion through wetland systems to strictly aquaculture
systems is a gradual change and all of these systems
are influenced by similar scientific principles. For this
reason, this discussion of land application will cover
some concepts which some people would consider as
more aquatic than agronomic in nature.
The EPA is a young agency which was formed by
Executive action in December 1970. Historically, the
involvement of the WQCB in research,, on land
application of municipal wastewaters predates the for-
mation of EPA by many years. Projects supported by
predecessor agencies, including the Federal Water
Quality Administration, the Federal Water Pollution
Control Administration, and the U.S. Public Health
Service, are an integral part of technical data base be-
ing developed by the WQCB. The results of these
projects conducted under the auspices of predecessor
agencies provide much of the current data base and
serve as the principal guides for the direction of pres-
ent and future research goals.
The major thrust of current research efforts is a
quantitative assessment of the capability of existing
land application approaches to meet the goals of PL
92-500. Hundreds of facilities which are in current use
serve as readily available sites for research evaluation.
THE CURRENT
One can conceive numerous approaches for utiliz-
ing land application in the management of
wastewaters. The options available involve varying
degrees of pretreatment, a long list of cropping prac-
tices, and several choices for release of the renovated
wastewater. Only a few of the many options have
practical significance for use within the current time
The variety of climatic conditions, system ages, and
site management practices available at these sites can-
not be duplicated in the laboratory or through initia-
tion of new field projects. Studies of these existing
facilities are self-limiting and must be supplemented
by laboratory work on fundamental processes and by
field demonstration of designs incorporating new con-
cepts. The WQCB has seven in-house projects and ten
extramural projects addressing many aspects of
wastewater management incorporating land applica-
tion in the overall management concept.
Future research objectives are focused on the short-
term needs of the wastewater management complex,
as well as the long-range goals of PL 92-500. Short-
term needs are designated as those associated with im-
provements scheduled for adoption within five years,
while the long-term needs are designated as those
associated with the 1983 and 1985 goals of the Water
Pollution Control Act of 1972. Short-term plans place
emphasis on expanding our quantitative data base
through investigation of current operations involving
crop irrigation and infiltration systems. Complemen-
tary research will be conducted to develop innovative
approaches for achieving secondary treatment or more
advanced levels of treatment for implementation prior
to 1978. Long-range plans provide more flexibility for
evaluation of integrated systems directed to the
achievement of non-polluting discharge of treated
wastewaters. Plans for obtaining this goal incorporate
more laboratory studies and field development studies
directed to modifying existing practices, combining
process units to achieve better reuse of wastewater
constituents, and exploring new ideas for incor-
porating wastewater reuse into the production of food
and fiber products.
DATA BASE
schedule for improving wastewater management
facilities. We in the WQCB have categorized those
land application approaches having potential for im-
mediate use into three groups. These groups are (1)
crop irrigation which includes both field and forest
cropping systems, (2) infiltration-percolation which
includes all types of recharge systems, and (3)
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overland-flow which includes all systems with planned
runoff. The current state of knowledge for each of
these groupings is at radically different stages of
development and choices for project implementation
vary accordingly. One considering the implementa-
tion of a crop irrigation project in a water-short area
could expect generally favorable response to im-
plementation of a project, while one considering the
same type of crop irrigation project in a cool and
humid region could expect closer scrutiny from
government and public sectors. One considering
overland flow for treatment of municipal wastewaters
could expect rejection of anything but a development
project involving research. These differing responses
reflect the confidence or lack of confidence in the
current technical data base. Improvement of the data
base and dissemination of information at workshops
and symposia like this one is an effective tool for
providing the most recent technical data to decision
makers.
CROP IRRIGATION SYSTEMS
Crop irrigation has been practiced for many
decades and there is a great volume of qualitative in-
formation substantiating the benefits of utilizing
treated wastewaters for irrigation in water-short areas.
Technical information sources such as the survey con-
ducted by Sullivan, Cohn, and Baxter1 and the state-
of-the-art report by Pound and Crites2 provide com-
prehensive information on past and current practices.
Summary type sources like these and reports on
specific projects such as the renovation project at
Pennsylvania State University3 can be combined with
the information in previous symposia4'5'6 to make
several technical judgments about utilization of crop
irrigation systems. Specific areas of interest include
pretreatment, site characteristics, acceptable loading
rates, methods of application, crop response, effects on
soils, and effects on groundwater.
Technical information accumulated over the last 75
years shows the following regarding pretreatment
before irrigation use. The most common pretreatment
provided is that which has been commonly referred to
as secondary treatment and is achieved with processes
such as activated sludge, trickling filters, or oxidation
ponds. Polishing ponds are frequently used following
the activated sludge or trickling filter process.
Chemical disinfection may or may not be included,
depending upon the type of crop to be irrigated with
the effluent. Irrigation of park areas, golf courses, and
human food crops are examples of uses where it is
more characteristic for the treatment train to include
secondary treatment, retention in a polishing pond,
and chemical disinfection prior to use for irrigation.
Irrigation of forage and fiber crops is often practiced
without chemical disinfection as the final step. Irriga-
tion with primary effluents is still practiced to some
degree where the crop to be irrigated is a forage or
fiber crop. The practice of irrigating crops with
primary effluents has declined substantially since the
1930's just as the practice of irrigating crops with raw
settled sewage declined from 1900 to 1930 and has
been virtually abandoned in the United States.
Decline in the application of raw sewage to the land
has paralleled the decline in discharge of raw sewage
to surface waters. There is a good technical data base
to link outbreaks of human illness with contamination
of foods by raw or partially treated sewage via either
land application or discharge to surface waters.
Bryan7 tabulated 73 outbreaks of human illness
associated with sewage contamination of foods. He
reports that foods grown in water were the vehicle in
42 cases (water discharge) and vegetables, fruits, or
beef were the vehicle in 28 cases (land application).
Technical information such as this provides a sound
data base to support the trend toward secondary treat-
ment prior to most irrigation uses.
Site characteristics for the hundreds of facilities
currently in operation vary greatly. Numerous sources
including those already cited and numerous others
referred to in a recent publication of 570 abstracts8
show that there are no hard and fast guidelines which
describe the one best site. Site selection must be ap-
proached on a case-by-case basis with attention to the
fundamentals of soil properties, the local hydrologic
cycle, the local climate, and the overall objectives of
the planned waste-water management system. Soil
properties exhibited by medium-textured soils offer a
compromise between the hydraulic limitations im-
posed by clay soils and the poorer contaminant
removal of the hydraulically desirable sands. Fre-
quently, the choice between available sites will depend
heavily on the texture of the soil. The local hydrologic
cycle is a key factor which has been overlooked all too
often in the assessment of site characteristics. The
remedial action required to correct the resultant
water-logging of a site can be difficult and costly. Par-
sons9 gives an account of system modifications which
are quite typical. Pound and Crites,2 page 186,
recount a more complicated resolution of a
water—logging problem. Experiences such as these
demonstrate the results of overlooking the hydrologic
cycle. It is a sound technical judgment to consider ar-
tifical means of drainage when a site assessment leaves
doubt about the capability of the natural cycle to han-
dle the added water load. Acceptable loading rates are
site specific but can be expected to fall within the range
of 2.5 to 10 cm per week (1 to 4 inches per week). By
our definition of land application systems, we ar-
bitrarily place application rates greater than 10 cm
per week in the infiltration-percolation or overland-
flow categories. The application rates must be selected
to be compatible with the soil and climatic conditions.
Clay soils in cool regions dictate lower rates, while
sandy soils can accommodate higher rates in most
localities. For example, the Muskegon wastewater
management system, which is an underdrained
system on sandy loams with a naturally occurring
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shallow water table, has a design load of 8.5 cm per
week (3.4 inches per week). The hydraulic load is fre-
quently the limiting factor for determining area re-
quirements but there are other factors which are con-
tributory and may be the limiting factor. Nitrogen
bleed-through to the underlying groundwater may
become an increasingly important factor in this
respect. Nitrogen removal by crop irrigation systems is
largely dependent on crop uptake and removal of the
crop. In cases where nitrogen bleed-through (usually
in the form of nitrate) is not acceptable, a nitrogen
loading somewhat greater than that which can be
removed in the harvested crop may limit the hydraulic
loading.
The crop response to sewage irrigation has been
well documented as to yield and some specific factors
regarding composition. There is conclusive evidence
that yields are comparable to those achieved with the
use of fresh water for irrigation and commercially
available mineral fertilizers. The generally observed
increase in vegetative yield is not always a benefit
because there are other factors which influence the
value of a crop. For instance, sugar beets and sugar
cane may yield more tonnage but less total sugar due
to a reduction in sugar content. The choice of crop is
largely a management and marketing decision which
must be integrated into the overall project plan. It
may be technically sound to select a crop and manage-
ment option which results in average crop returns
rather than high crop returns.
Use of treated wastewater for irrigation does have
effects on the soils. These effects are site specific and
are substantially different in arid and semi-humid
regions. The technical data available indicates that
secondary effluents have been used for many decades
without noticeable effects on the soil when used at nor-
mal irrigation rates. The EPA10 has issued criteria for
the use of treated wastewaters as a source of irrigation
water. Effluents meeting these criteria should not
affect the properties of the soil sufficiently to reduce
crop yields or cause severe management problems.
Crop irrigation systems contribute a fraction of the
applied wastewater to underlying formations after
passage through the soil. The fate of this fraction of
the applied wastewater and its potential effect on the
composition of existing groundwater is a complex
issue. The nature of potential effects on groundwater
is dependent on many factors related to the quality of
the waste treatment plant effluent, concentration
changes induced by climatic influences, quality
changes effected by the plant-soil community, and the
occurrence and quality of existing groundwater. There
are several prime factors to consider in the technical
assessment of a project in the planning process.
Climatic conditions in the east favor the situation
where existing groundwater will be of substantially
better quality than the applied wastewater in most
situations. Present technical information presents a
sketchy data base because the practice of crop irriga-
tion with treated wastewaters is not prevalent in the
east. Data available for systems which have seen long
service in semi-arid regions is not a sound technical
base for use in the east because the concentration
changes induced by climatic influences are radically
different. Those projects which include recovery of the
renovated wastewater or delineate a monitored zone of
groundwater influence show the best conformity with
existing technical knowledge.
INFILTRATION-PERCOLATION
Like crop irrigation, the use of various infiltration-
percolation concepts including recharge basins, ridge
and furrow systems, and spray disposal systems has
been practiced for many decades. Unlike crop irriga-
tion, these systems have been utilized primarily for
"waste disposal" or more appropriately as one process
unit in a "waste treatment" system. This approach
has been practiced extensively for management of
municipal wastewaters and industrial wastewaters.
Our discussion of this topic will be limited to the use of
infiltration-percolation systems as an advanced waste
treatment approach for municipal effluents. Pertinent
information sources are limited primarily to project
reports for specific facilities such as those at Santee,
California," Phoenix, Arizona,12 Detroit Lakes,
Minnesota,13 and Lake George, New York.14 Pound
and Crites2 assess current technical information as
well as provide details on several active systems.
Several agencies are collecting information on other
systems at the present time and the technical data
base is expanding rapidly. Consequently, technical
judgments made today are subject to revision or
refinement in the near future. Specific areas of interest
include pretreatment, site characteristics, acceptable
loading rates, the role of crops, treatment achieved,
and effects on groundwater.
The use of infiltration-percolation systems in the
management of municipal wastewaters has been
directed to the polishing of primary or secondary
effluents prior to their discharge into receiving waters.
The majority of these facilities provide secondary
treatment prior to use of infiltration-percolation for
advanced treatment. Assessment of operations at ex-
isting facilities indicates that advantages attributed to
providing secondary treatment include much greater
acceptable loading rates, better control of nuisance
vectors, and less trouble with soil clogging. The
available technical data support the contention that
these advantages justify the cost of providing classical
secondary treatment. There is ample technical data to
substantiate the effectiveness of intermittent soil filtra-
tion as an effective means for achieving fecal coliform
reduction equivalent to that of chemical disinfection,
therefore, chemical disinfection as a routine pretreat-
ment practice is technically questionable in many
situations.
Site characteristics favorable for the use of
infiltration-percolation differ substantially from those
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most suited to crop irrigation. The most favorable sites
are easier to define because soil properties, the local
hydrologic cycle, and project objectives place more
constraints on the site characteristics. The best suited
sites would have three meters or more of an un-
saturated sandy soil overlying an impervious barrier
or a water table with restricted vertical permeability.
The restriction to vertical permeability would permit
ready recovery of the renovated water or promote
lateral movement through the permeable formation to
a nearby surface discharge as a seep or spring. A good
example of a favorable site in a cool, humid climate is
the Lake George, New York facility.14 There is a good
technical data base for projecting the performance of
infiltration-percolation systems and those sites which
provide for containment or recovery of the renovated
water can be readily assessed with available data.
Sites which do not have favorable characteristics must
be considered on a case-by-case basis and require
more site evaluation work. The evaluation of the site
should provide data to assure the attainment of a
desired level of advanced treatment without water-
logging the site or causing unacceptable quality
changes in an existing groundwater body.
The concept of the infiltration-percolation system is
directed to relatively high loading rates. Acceptable
rates vary greatly because they are site specific but
they range from about 10 meters to 100 meters per
year. The available technical data base has not been
sufficiently developed to provide a ready reference for
selecting loading rates. Some on-site testing of infiltra-
tion rates and transmissibility are needed to assure
selection of an acceptable long-term loading rate. This
on-site testing should determine that aerobic condi-
tions can be maintained at the proposed loading rate
and that the natural hydrologic cycle or an artificially
induced subcycle will maintain a minimum un-
saturated depth of more than one meter. Soil systems
operating at these high loading rates do not have the
capability to remove many inorganic constituents as
effectively as the crop irrigation systems. Removal of
nitrogen is of specific interest in this instance since
areal loadings are high and much of the applied
nitrogen appears in the renovated water in the nitrate
form. The control of denitrification in the soil environ-
ment offers a practical mechanism for obtaining
nitrogen removal by converting the nitrogen forms
found in the wastewater effluent to nitrogen gas.
Research is under way to develop reliable technology
for effective use of the denitrification process.
The role of crops in the effectiveness of infiltration-
percolation systems is of minor consequence. Nutrient
loadings greatly exceed plant uptake rates and the in-
fluence of crop removal is a minor factor in the mass
removal of potential contaminants. Some evidence is
available which shows that cover crops are effective in
the maintenance of the infiltration rates, however,
there is divided opinion on this benefit and many
infiltration-percolation systems are operated without
any vegetative cover. The technical data base current-
ly available indicates cover crops are not necessary for
successful operation of infiltration-percolation systems
for advanced treatment of municipal treatment plant
effluents.
The treatment achieved by infiltration-percolation
systems has been well established for many con-
taminants remaining in secondary effluents. Con-
taminants which are essentially eliminated by the
infiltration-percolation process include suspended
solids, biochemical oxygen demand, fecal coliforms,
and certain viruses. Phosphorus can also be reduced to
very low levels, typically less than 0.5 mg/1, with ap-
propriate travel distances of several hundreds of
meters and retention times of several weeks. Other
contaminants including pesticides, heavy metals, and
selected inorganic species are substantially reduced
but the degree of removal for individual species has
not been established through the accumulation of a
reliable data base. Like phosphorus, the removal of
many of these species is a function of residence time
and travel distance involving physical, biochemical,
and chemical interactions of considerable complexity.
Readily soluble ionic species including sodium,
chloride, nitrate, and sulfate are not appreciably
reduced by infiltration-percolation systems and can be
expected to remain in the renovated water after long
distances of travel and long residence times. Interest in
many potential contaminants such as heavy metals
and pesticides has developed recently and the
historical data base on the treatment efficiency of
infiltration-percolation contains little quantitative
data for these contaminants. The historical data base
does contain much reliable data on the excellent
removal achieved for suspended solids, biochemical
oxygen demand, fecal coliform, certain viruses, and
phosphorus. Comprehensive study of on-going
facilities will provide quantitative data to fill gaps in
the current technical data base.
Infiltration-percolation system designs incorporate
underground storage of the renovated wastewater,
therefore, the effects of these systems on the quality of
existing groundwater is a fundamental factor to con-
sider in the planning stage. Infiltration-percolation
systems do, as already discussed, achieve excellent
removal of many of the residual contaminants in
secondary effluents. These removals do not assure a
water with a quality equal to that of existing
groundwaters. In special situations the quality of the
renovated wastewater may be better than that of the
existing groundwater and recovery of the renovated
water before it merges with existing groundwater may
be desirable. This would not be a common occurrence,
particularly in the eastern United States, and
technical evaluation of a proposed infiltration-
percolation system will usually be directed to
maintenance of desired groundwater quality by selec-
tion of specific management techniques. One positive
technique is containment and recovery of the
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renovated wastewater for reuse or direct surface dis-
charge. A second positive technique is the selection oi
a site which assures discharge to a surface water
through a naturally occurring underground flow ter-
minating in a nearby surface seep. The flow path to
the surface seep should not be subject to use for water
supply wells without appropriate monitoring prac-
tices. A third technique for management of
infiltration-percolation effects on groundwater quality
is that of artificially inducing dilution or utilizing
naturally occurring dilution in the groundwater body
to maintain desired groundwater quality.
The technological base for adoption of any one of
these three management techniques varies in reliabili-
ty. Obviously, the containment and recovery tech-
nique offers the easiest case for substantiation and
there is a good data base available. Underground
flow to a natural surface seep is more difficult to sub-
stantiate but there are several existing systems which
are being or can be studied to improve the reliability of
the technical data base. The underground dilution
technique requires extensive on-site evaluations to
determine the relative quality of the secondary effluent
to be applied, the renovation achieved by infiltration-
percolation, the quality of the existing groundwater,
the amount and quality of natural or other man-
provided dilution waters, and the final quality of the
blended water. Development of a reliable technology
base for this underground dilution technique will re-
quire detailed evaluations at many demonstration-
type facilities.
OVERLAND FLOW
Overland-flow treatment of municipal wastewaters
is an essentially new concept for implementation in
the United States. Successful management of food
processing wastewaters by this technique,15 some data
from a few facilities in England16 and Australia,17 and
progress reports for two on-going research efforts in
the United States18-19 are the principal sources for the
current technical data bank. The information available
indicates this approach has potential as an alternate
approach for treatment of raw wastewater or as a
technique for upgrading primary and secondary
effluents from conventional treatment plants. The
overland-flow approach is a treatment approach
which is suited to sites with very low infiltrative
capacity. The basic concept of the approach is to use
the surface soil and the associated plant and animal
life as an integrated biochemical and chemical treat-
ment process. Wastewater is applied to a smoothed
and sloping area covered with grass. The applied
wastewater moves downslope by sheet flow to a point
where it is intercepted by a terrace ditch for discharge
to a surface water. Development of a data base for
treatment of municipal wastewater by this approach is
just beginning to emerge. Information pertaining to
site characteristics, management concepts, the role of
crops, and effects on the surroundings can be deduced
from experiences with other wastewaters. Specific
data on pretreatment effects, acceptable loading rates,
and treatment efficiency must be developed through
laboratory and field testing programs. Overland flow
is being covered in this discussion of practical land
application approaches because it has great technical
potential for providing advanced treatment of raw
municipal wastewater at a cost comparable to the cost
of primary treatment. It accomplishes this treatment
with the added benefit of eliminating the production
and subsequent handling of sludges.
The technical feasibility of employing overland flow
to treat raw municipal wastewater has been
demonstrated by three years of study at RSKERL.
The results of this research effort show that an average
load of 10 cm/week can be applied in climates com-
parable to that of south central Oklahoma. The
effluent from the overland flow area would be substan-
tially better than required to meet the current EPA
definition of secondary treatment with respect to
suspended solids and biochemical oxygen demand.
The pH would be in the specified range and disinfec-
tion to meet the coliform criteria would require com-
paratively low doses of disinfectant due to lack of in-
terfering constituents. Removal of about 85 percent of
the total nitrogen and about 60 percent of the total
phosphorus are added benefits of normal manage-
ment. A study to assess system performance while
treating a 380 m3 per day flow (0.1 mgd) will start
operation in the spring of 1975 at a south central
Oklahoma community.
Overland flow or grass filtration following primary
or secondary treatment is currently practiced in
Australia and England. Treatment of raw settled
sewage has been practiced seasonally at Melbourne,
Australia17 for several decades. The objective of this
practice is to provide acceptable wastewater treatment
in the cool and rainy winter period when crop irriga-
tion is not being practiced in the pasture area. Kirby17
reports removals of 95 percent for suspended solids, 96
percent for biochemical oxygen demand, 60 percent
for nitrogen, and 35 percent for phosphorus with con-
tinuous application at a rate of 14 cm per week for the
grass filtration area. Walker16 reports on the effec-
tiveness and cost of grass filtration as a method of
polishing secondary effluents in England. He reports
on costs, rates of application, and the improvement in
treatment efficiency at four installations. About 60
percent of the suspended solids and biochemical ox-
ygen demand in the secondary effluents were removed
by grass filtration at loading rates of .06 to 0.25 m3/m2
per day (.05 to 0.22 mgd/acre). Studies under way by
Hoeppel, et al.18 will advance our knowledge of the
overland-flow process and may act as the seed for
growth of a technological base to establish overland
flow as a technique for polishing secondary effluents in
the United States.
-------
EPA RESEARCH
We have touched on EPA research efforts in the dis-
cussion of current land treatment options. Now, let us
address some completed or ongoing studies in more
detail as well as projecting our plans for filling the
gaps in the technological data base. Detailed discus-
sion of the results of completed or ongoing studies will
be directed to clarification of technical judgments
regarding the present technical data base. Discussion
of future plans will provide insight into the type of ad-
ditional information being sought and an estimate of
when various bits of information will become
available.
COMPLETED AND ONGOING STUDIES
In keeping with the arrangement of the discussion of
current options, this discussion will address crop
irrigation, infiltration-percolation, and overland-flow
projects separately. An additional category of basic
research applicable to more than one category will
close the section.
Crop Irrigation
Cropland irrigation with municipal effluents is a
well-established practice in the southwestern United
States. Many facilities have practiced effluent irriga-
tion for more than 30 years at the same site. Utiliza-
tion of the practice has grown steadily since the first
operations were initiated in the late 1800's and some
300 facilities are active at present. In spite of this im-
pressive number of active facilities, there is an obvious
lack of quantitative data to delineate the balance
between the beneficial and adverse influences on the
local environment. Our laboratory has completed or is
actively involved in ten field projects addressing
various aspects of crop irrigation practices.
One group of projects places emphasis on locating
and evaluating currently available quantitative infor-
mation on application rates, crop responses, soil
changes, and groundwater quality changes. To date,
this approach has been very useful in defining
management techniques for general use in the
Southwest, as well as furnishing a base for other
geographic locations. A recently completed survey of
existing facilities1 and an assessment of current
technology2 summarize the accomplishments.
A second group of projects is designed to
demonstrate crop irrigation approaches in geographic
areas where historical information is scarce. The long-
term project at Pennsylvania State University3 is an
example of a project of specific regional significance.
The ten years of data collection at this site shows that
crop irrigation can benefit crop production in a cool,
humid climate with little effect on the local
groundwater body. Other ongoing demonstration
projects of specific interest include the Muskegon
Wastewater Management System; a smaller study at
Belding, Michigan; a study at Falmouth,
Massachusetts; and a study at Tallahassee, Florida.
The Muskegon project is designed to demonstrate
seasonal irrigation in conjunction with off-season
storage of all treated wastewater, as well as complete
recovery of the renovated wastewater for surface dis-
charge. This total containment system represents a
very advanced concept of crop irrigation for
wastewater management. The 1975 season will be the
first for collection of full season data for all system
components. Data collected over the next several years
will be an important addition to the current data base.
The study at Belding, Michigan utilizes an oxidation
pond effluent (a 5-cell pond system) in a summer
irrigation program for forages, sod, and ornamentals,
and in a winter irrigation program for forages. This
study is providing additional data on winter
operations, responses of sod and ornamentals, and
water quality influences resulting from non-
containment operations. The site has sandy soils over
a shallow water table which promotes lateral move-
ment through interflow with discharge to a surface
stream. The Falmouth, Massachusetts study is de-
signed to demonstrate several management techniques
on sandy soils with recharge of the groundwater
in a sand aquifer at a depth of about ten meters. The
Tallahassee, Florida study has a similar objective for a
project site with radically differing climatic con-
ditions. Interpretative data from these projects will
become available within a year or two.
Infiltration-Percolation
Infiltration-percolation is a well-established prac-
tice at many small municipal facilities throughout the
United States. Design and operation of these systems
have emphasized the safe disposal of a treatment plant
effluent, and it is only within the last decade that an
effort has been made to determine the treatment
which can be achieved by adjusting the management
of a system. Our laboratory has been or is actively in-
volved in nine field studies addressing the evaluation
and demonstration of management options which
enhance the treatment achieved by infiltration-
percolation systems.
Previously completed studies include four research
studies in water-short southwestern states and two
research studies in water-rich north central states.
The studies in the southwest were conducted at Whit-
tier Narrows, California,19 Santee, California,11
Phoenix, Arizona,12 and Hemet, California.20 The
studies in the north central area were in Detroit Lakes,
Minnesota,13 and Westby, Wisconsin.21 The study at
Whittier Narrows, California was conducted to study
the effectiveness of the infiltration-approach for direct
recharge of a potable groundwater supply with secon-
dary effluent.19 The results of this study showed that
spreading periods of about 9 hours followed by drying
periods of about 15 hours produced a clear and highly
oxidized water acceptable for recharge at this site.
This method of operation resulted in conversion of
-------
almost all applied nitrogen to nitrate and produced
nitrate concentrations in the renovated water two to
three times more than acceptable limits for drinking
water. Due to the high nitrate concentration, it was
recommended that dilution with low nitrate water
would be necessary before repumping for use as a
water supply. The concurrent study at Santee,
California evaluated the use of infiltration-percolation
to make municipal effluent suitable to fill and main-
tain the water level in recreational lakes.11 Locating
the infiltration-percolation basins in the alluvium of a
shallow stream channel provided substantial lateral
movement underground after about 3 meters of ver-
tical percolation. In addition to excellent removal of
solids, oxygen-demanding substances, pathogens, and
phosphorus, total nitrogen in the renovated water was
reduced to 1.5 mg/1 (from 25 mg/1 applied to
spreading basins) after about 500 meters of lateral un-
derground travel. Emphasis was placed on evaluating
this nitrogen removal at the Phoenix, Arizona study
using a similar mode of operation.12 Results of the
Phoenix study showed that the frequency of applica-
tion has a major influence on nitrogen removal.
Spreading and drying periods of a few days or less
promoted nitrification and resulted in less than 10 per-
cent total nitrogen removal, whereas spreading and
drying periods of 10 to 20 days resulted in apparent
denitrification and up to 80 percent nitrogen removal.
This study also highlighted the importance of un-
derground residence time and/or distance of travel for
achieving phosphorus removal at the high loadings
used for the infiltration-percolation approach.
Another important factor related to local
hydrological conditions was graphically demonstrated
by the study at Hemet, California.20 An unusually wet
winter season at this location caused the local water
table to rise up to the bottom of the spreading basins.
The resultant reduction in hydraulic acceptance rate
and deterioration of treatment efficiency made it
necessary to quickly develop an alternate method for
handling their effluent.
Although the two north central area studies repre-
sent radically differing climatic conditions, overall
performance was quite similar to that observed in the
southwest. The Detroit Lakes, Minnesota project en-
tailed a four-year experiment using 20-hour spraying
periods followed by 4-hour drying periods to apply
about 30 meters per year of effluent on a sandy soil.13
Our definitions place this system in the infiltration-
percolation category even though it uses spray
application and is referred to as a spray irrigation
system. It is significant that the use of short spreading
and drying cycles in this climate produced nitrogen
and phosphorus interactions comparable to those for
studies in the southwest. Nitrogen was converted to
nitrate which appeared in the groundwater (at a con-
centration comparable to that in a municipal effluent)
while 70 percent of the phosphorus was removed after
no more than 7 meters of travel distance through the
soil. The other study in this climate was a one-year
evaluation of the performance of an existing ridge and
furrow basin facility.21 The system was located on a
silt loam soil and a loading of about 15 meters per year
was obtained with wetting periods of two weeks
followed by drying periods of two weeks. As was the
case for the study in Arizona, the long spreading
period resulted in about 70 percent removal of total
nitrogen without affecting the removal capacity for
other measured parameters.
The first of several studies to make comprehensive
evaluations of existing infiltration-percolation facilities
has just been initiated at Lake George, New York.
Several studies of this type will be implemented to ex-
pand the scope of quantitative data to include
parameters of current interest. Completed and ongo-
ing research on the infiltration-percolation approach
to land spreading of municipal effluents are en-
couraging for future use on a much larger scale.
Technological data are already available to design and
operate systems for a limited number of situations, but
of more importance is the apparent utility of the ap-
proach under widely differing climatic conditions. We
are optimistic that further research efforts can es-
tablish well-defined design criteria and management
techniques for use throughout the United States.
Overland Flow
Overland-flow treatment of municipal wastewaters
is a newly developing technology in the United States.
Our laboratory has completed an 18-month study to
assess the technical feasibility of treating raw sewage
by overland flow.15 The positive results of this study,
as well as a just completed 15-month extension of the
study to explore alum addition for improving
phosphorus removal have led to two new studies. One
of these is a field evaluation to study overland flow for
a 380 m3 daily flow (0.1 mgd) at a small rural city.
The second is a test to compare treatment efficiency
and area requirements for primary and secondary
effluents as opposed to direct treatment of raw sewage.
These efforts are a small fraction of the total effort
which will be required to establish overland flow as a
viable alternative to other established wastewater
management approaches.
Basic Research
In addition to studies addressing specific land
application approaches, our laboratory is conducting
or has supported several studies on fundamental
processes which are involved in the functioning of land
application systems. Studies have been focused on
special aspects of phosphorus retention in soils,
denitrification, biodegradation of organics, and cli-
matology.
Phosphorus retention in soil has been studied from
the specific aspect of predicting long-term phosphorus
removals by measurement of specified soil properties.
Enfield22 has reported an initial prediction model
-------
based on laboratory work with 26 mineral soils.
Completed and ongoing denitrification studies are ad-
dressing the relation of oxygen status in an attempt to
delineate management approaches for achieving and
maintaining 90 percent nitrogen removal by
denitrification. Continuing studies on biodegradation
of organics have addressed the use of ATP (adenosine
triphosphate) as a tool to measure bioactivity and the
use of small-scale laboratory apparatus to assess the
relative biodegradability of wastewaters from different
sources. The study of climatology has been directed to
assessing the value of readily available weather data
for determining winter storage needs. These basic
studies have applicability to all three land application
approaches and provide a better basis for establishing
field projects to develop or demonstrate specific
features of improved technology.
FUTURE RESEARCH
Future plans for research on land application ap-
proaches adhere to our categorization of land applica-
tion into three specific types of systems. The short-
range plans call for utilization of studies on existing
systems and selected demonstration projects to gain as
much improvement in the data base as is possible in a
short time. These short-range plans address the 1977
and to some degree the 1983 milestone dates of PL 92-
500. The long-range plans call for directing more
attention to the study of innovative combinations of
land application alone or with other process units to
achieve a very high degree of contaminant control.
These long-range plans address the 1985 goal of non-
polluting discharge, as well as the intermediate 1983
goal of best practicable waste treatment technology.
SHORT-RANGE PLANS
Projected Branch support over the next two to three
years will provide a diversified program which will
make important gains in all four of the major research
areas. Emphasis will be placed on filling technology
gaps for the crop irrigation and infiltration-
percolation approaches which are being implemented
as alternative wastewater management systems at the
present time. Development of overland-flow
technology will be aimed at assisting small rural com-
munities needing a simple and economical secondary
process. Basic research will continue with little change
in goals or emphasis.
A major fraction of short-term support will be
allocated to collection of quantitative data at about ten
existing crop irrigation systems and ten existing
infiltration-percolation systems. These one- to two-
year studies should be completed by the end of FY
1977 and the results of the studies will be distributed
as technical information bulletins shortly thereafter.
The short-range plans also call for initiation of several
demonstration projects in anticipation of a need to
demonstrate improved management techniques for
the crop irrigation and infiltration-percolation
systems. Efforts will be made to select project sites in
geographical locales where governmental units and
the public are interested in the potential of land
application but do not have ready access to observe an
ongoing facility. These short-term efforts on the crop
irrigation and infiltration approaches will emphasize
the collection of quantitative data to delineate the cans
and cannots of existing design technology. Major ef-
forts to develop new design technology will be con-
sidered as a long-range objective.
The short-term plans for overland-flow studies also
address the development of new technology as do the
basic research studies. Short-term objectives for
overland-flow studies will emphasize two areas of
development. One of these will be the development of
overland flow as a unit process for treatment of raw
municipal wastewaters on a year-round basis in
southern states. Overland flow will offer many rural
communities a much needed method for meeting or
exceeding the present definition of secondary treat-
ment at a cost comparable to that of primary treat-
ment.
The second objective will be the development of
overland flow as a seasonal operation for upgrading
existing pond systems which cannot meet present
criteria for secondary treatment. The prospects for
developing a timely data base for these two objectives
are good and there is an obvious need for the intended
results. Basic research will continue in the areas
already under study, as well as being expanded to in-
clude work on heavy metals. Short-term goals include
positive identification of denitrification as the
mechanism for nitrogen removal by overland flow; es-
tablishment of a method for predicting soil removal of
phosphorus; a routine methodology for predicting
winter storage needs from weather station data; and
development of the ATP procedure for measuring
bioactivity in soils. Completion of work in other areas
will fall under long-range plans.
LONG-RANGE PLANS
Projected Branch support from FY 1977 through
FY 1981 should support a program which will
culminate in the distribution of technical bulletins on
crop irrigation, infiltration-percolation, and overland
flow. These technical bulletins will detail procedures
for planning a land-based wastewater management
system, selecting the process train best suited to the
site, designing the system, and operating the system.
These technical bulletins will be complemented by a
series of research reports providing reliable technical
data which substantiate the recommendations con-
tained in the .bulletins. Much of the data in the
research reports will have come from demonstration
projects which will still be in operation as permanent
facilities. Establishment of demonstration projects at
10
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sites where operations will continue for several
decades is a key objective in long-range plans. The
value of these sites for visual inspection and periodic
collection of quantitative data is an essential building
block for establishing a reliable data base which can
be extended beyond the immediate needs for revamp-
ing our wastewater management methodology.
REFERENCES
1. Sullivan, Richard H., Morris M. Cohn, and
Samuel S. Baxter. Survey of Facilities Using Land
Application of Wastewater. Environmental
Protection Agency, Washington, D.C. Report No.
EPA-430/9-73-006. July 1973. 377 pp.
2. Pound, Charles E., and Ronald W. Crites.
Wastewater Treatment and Reuse by Land
Application—Vol. II. Environmental Protection
Agency, Washington, D.C. Report No.
EPA-660/2-73-006b. August 1973. 249 pp.
3. Kardos, Louis T., William E. Sopper, Earl A.
Myers, Richard R. Parizek, and John B. Nesbitt.
Renovation of Secondary Effluent for Reuse as a
Water Resource. Environmental Protection Agen-
cy, Washington, D.C. Report No.
EPA-660/2-74-016. February 1974. 496 pp.
4. Wastewater Use in the Production of Food and
Fiber—Proceedings. Environmental Protection
Agency, Washington, D.C. Report No.
EPA-660/2-74-041. June 1974. 568 pp.
5. Proceedings of the Joint Conference on Recycling
Municipal Sludges and Effluents on Land. Nat'l
Ass'n. of State Universities and Land-Grant
Colleges, Washington, D.C. (Champaign, Illinois.
July 9-13, 1973.) 244 pp.
6. Conference on Recycling Treated Municipal
Wastewater Through Forest and Cropland.
Sopper, William E., and Louis T. Kardos
(editors). Environmental Protection Agency,
Washington, D.C. Report No. EPA-660/2-74-
003. March 1974. 463 pp.
7. Bryan, Frank L. Diseases Transmitted by Foods
Contaminated by Wastewater. In: Wastewater
Use in the Production of Food and
FiberlProceedings. Environmental Protection
Agency, Washington, D.C. Report No.
EPA-660/2-74-041.-June 1974. pp. 16-45.
8. Water Quality Control Branch. Land Applica-
tion of Sewage Effluents and Sludges: Selected
Abstracts. Environmental Protection Agency,
Corvallis, Oregon. Report No.
EPA-660/2-74-042. June 1974. 248 pp.
9. Parsons, W. C. Spray Irrigation of Wastes from
the Manufacture of Hardboard. 22nd Industrial
Waste Conference. Vol. 52, No. 3. July 1968. pp.
602-607.
10. Water Quality Criteria 1972. Environmental
Protection Agency, Washington, D.C. Report No.
EPA-R3-73-033. March 1973. pp. 324-353.
11. Merrell, John C., Jr., Albert Katko, and Herbert
E. Pintler. The Santee Recreation Project, Santee,
California (Summary Report). Public Health Ser-
vice Publication No. 99—WP—27. December
1965. 69 pp.
12. Bouwer, Herman, R. C. Rice, E. D. Escarcega,
and M. S. Riggs. Renovating Secondary Sewage
by Ground Water Recharge with Infiltration
Basins. Environmental Protection Agency,
Washington, D.C. Report No. 16060 DRV 03/72.
March 1972. 102 pp.
13. Larson, Winston C. Spray Irrigation for the
Removal of Nutrients in Sewage Treatment Plant
Effluent as Practiced at Detroit Lakes, Minnesota.
In: Algae and Metropolitan Wastes, Transactions
of the 1960 Seminar U.S. Dept. of Health, Educa-
tion and Welfare, pp. 125-129.
14. Aulenbach, Donald B., James J. Ferris, Nicholas
L. Clesceri, and T. James Tofflemire. Thirty-five
Years of Use of a Natural Sand Bed for Polishing a
Secondary Treated Effluent. (Presented at Rural
Environmental Engineering Conference. Universi-
ty of Vermont. September 27, 1973.) 46 pp.
15. Law, James P., Jr., Richard E. Thomas, and Leon
H. Myers. Cannery Wastewater Treatment by
High-Rate Spray on Grassland. J. Water Pollut.
Contr. Fed. 42:1621-1631. September 1970.
16. Walker, R. G. Tertiary Treatment of Effluent
from Small Sewage Works. Water Pollut. Contr.
77(2):198-201. 1972.
17. Kirby, C. F. Sewage Treatment Farms.
(Presented at Post Graduate Course in Public
Health Engineering, 1971. Session No. 12.
Melbourne, Australia.) 14 pp.
18. Hoeppel, Ronald E., Patrick G. Hunt, and
Thomas B. Delaney, Jr. Wastewater Treatment
on Soils of Low Permeability. U.S. Army
Engineer Waterways Experiment Station,
Vicksburg, Miss. Miscellaneous Paper Y—74—2.
115pp.
19. Thomas, R. E., K. Jackson, and L. Penrod.
Feasibility of Overland Flow for Treatment of
Raw Domestic Wastewater. Environmental
Protection Agency, Corvallis, Oregon. Report No.
EPA-660/2-74-087. July 1974. 30 pp.
20. Eastern Municipal Water District. Study of
Reutilization of Wastewater Recycled Through
Ground Water. Environmental Protection Agen-
cy, Washington, D.C. Water Pollut. Contr.
11
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Research Report Series No. 16060DDZ07/71. 22. Enfield, C. G., and D. C. Shew. Comparison of
Vol. 1. July 1971. Two Predictive Non-Equilibrium One-
21. Bendixen, Thomas W., et al. Ridge and Furrow Dimensional Models for Phosphorus Sorption and
Liquid Waste Disposal in a Northern Latitude. J. Movement Through Homogeneous Soils. J. En-
Sanit. Eng. Div., Proc. Am. Soc. Civil Eng. vir°n- Quality. Vol. 4, No. 1. January-March
P4(SA1):147-157. February 1968. 1975-
12
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Land Application Practices and Design Criteria
by
Charles E. Pound and Ronald W. Crites
Metcaff & Eddy, Inc.
Palo Alto, California
INTRODUCTION
Land application of wastewater or treated eltluent
involves the use of the soil surface and soil matrix for
renovation. Renovated water may discharge to
groundwaters or may be collected for surface water
discharge. Because land application involves physical,
chemical, and biological treatment, the renovated
water is generally comparable in quality to effluents
from advanced wastewater treatment processes.
The practice of land application is nationwide;
however the majority of the existing systems are found
in the west and southwest. As water quality re-
quirements become more stringent, alternatives that
involve land application will require increased con-
sideration. In this paper, the engineering aspects of
land application systems will be discussed for the ma-
jor techniques and a case study involving a
preliminary design will be presented.
LAND APPLICATION METHODS
Systems involving land application of municipal
effluents are normally categorized into three types of
systems based on differences in liquid loading rates,
land area requirements, and the interaction of the
wastewater with vegetation and soil. These three
categories are referred to as (1) irrigation, (2)
infiltration-percolation, and (3) overland flow. Selec-
tion of the method or combination of methods at a
given site is primarily governed by the drainability of
the soil, because it is this property that largely deter-
mines the allowable liquid loading rate. Schematic
diagrams indicating the major process characteristics
of each of the systems are shown in Figure 1. A sum-
mary of the comparative characteristics of the three
systems is presented in Table I1.
Irrigation
Irrigation involves applying effluent to the land, by
spraying or surface spreading, to support plant growth
and treat the effluent. This method is the most pop-
ular of land application techniques and is generally
the most reliable. Feed, fiber, and food crops can be
grown, provided the effluent is adequately treated to
meet public health standards. Forestland, parks, and
golf courses can also be irrigated.
Site Characteristics — The range of suitable site
characteristics for irrigation systems is wide. The ma-
jor criteria are as follows:
• Climate — Warm-to-arid climates are preferable
but more severe climates are acceptable if ade-
quate storage is provided for wet or freezing con-
ditions.
• Topography — Slopes up to 15 percent for crop
irrigation are acceptable provided runoff or ero-
sion is controlled.
• Soil type — Loamy soils are preferable, but most
soils from sandy loams to clay loams are suitable.
• Soil drainage — Well-drained soil is preferable;
however, more poorly drained soils may be
suitable if drainage features are included in the
design.
• Soil depth — Uniformly 5 to 6 feet or more
throughout sites is preferred for root development
and wastewater renovation.
• Geologic formations — Lack of major discon-
tinuities that provide short circuits to the
groundwater is necessary.
• Groundwater — A minimum depth of 5 feet to
groundwater is normally necessary to maintain
aerobic conditions, provide necessary renovation,
and prevent surface waterlogging. Control may
be obtained by underdrains or groundwater
pumping.
Irrigation Techniques — Three application techniques
are employed in irrigation systems (Figure 2):
• Spraying
• Ridge and furrow
• Flooding
Topography, soil conditions, weather conditions,
agricultural practice, and economics are factors to be
considered in technique selection.
Spraying involves the application of effluent above
the ground either through nozzles or sprinkler heads.
Other elements of the system include: pumps or a
source of pressure, supply mains, laterals, and risers.
Design of a system can be quite variable; it can be por-
table or permanent, moving or stationary. Spray
systems are the most efficient for uniform flow dis-
tribution, but such systems are also generally the most
expensive. High wind, a problem common to spray
irrigation systems, adversely affects efficiency of dis-
tribution and can also spread aerosol mists. Hydraulic
13
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EVAPORATION
CROP
SPRAY OR
SURFACE
APPLICATION
ROOT ZONE
SUBSOIL
SLOPE
VARIABLE
•DEEP
PERCOLATION
(a) IRRIGATION
EVAPORATION
SPRAY OR
-SURFACE APPLICATION
INFILTRATION
PERCOLATION THROUGH
UNSATURATEO ZONE
ZONE OF AERATION
AND TREATMENT
RECHARGE MOUND-
--<^ •>>. \> . . . .' Vv .;>.•
OLD WATER TABLE
(b) INFILTRATION-PERCOLATION
EVAPORATION
SPRAY APPLICATION
SLOPE 2-4%
GRASS AND VEGETATIVE LITTER
RUNOFF
COLLECTION
(c) OVERLAND FLOW
FIGURE 1. METHODS OF LAND APPLICATION
14
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Table 1. COMPARATIVE CHARACTERISTICS OF IRRIGATION, INFILTRATION-
PERCOLATION, AND OVERLAND FLOW SYSTEMS
Irrigation
Factor
Low-rate High-rate Infiltration-percolation
Overland flow
Liquid loading
rate, in./wk
Annual application,
ft/yr
Land required for
0.5 to 1.5
2 to 4
280 to 560
l.S to 4.0
4 to 18
62 to 560
4 to 120
18 to 500
2 to 62
2 to 5.5
8 to 24
46 to 140
1-ragd flowrate,
acres3
Application
techniques
Crop production
Soils
Climatic constraints
Wastewater lost to:
Spray or surface
Excellent
Fair
Usually surface
Poor
Usually spray
Fair
Moderately permeable
soils with good pro-
ductivity when
irrigated
Growing Storage
season often
only needed
Evaporation and
percolation
Rapidly permeable soils, Slowly permeable soils,
such as sands, loamy such as clay loams and
sands, and sandy loams clays
Reduce loadings in Storage often needed
freezing weather
Percolation Surface runoff and
evaporation with some
percolation
Expected treatment
performance
BOD and SS removal
Nitrogen removal
Phosphorus removal
98+t
85+ta
80 to 99t
85 to 991
0 to SOt
60 to 951
92+t
70 to 90t
40 to SOt
a. Dependent on crop uptake.
Metric conversion: in. x 2.54 • cm
ft x 0.305 • m
acre x 0.405 - ha
design factors for spraying systems are included in
references 2iM
Ridge and furrow irrigation is accomplished by
gravity flow of effluent through furrows, from which it
seeps into the ground. Utilization of this technique is
generally restricted to relatively flat land, and exten-
sive preparation of the ground is required. The
operating cost is relatively low, and the technique is
well suited to certain row crops. Uniformity of dis-
tribution, however, is difficult to maintain unless slope
irregularities are eliminated.
Irrigation by flooding is accomplished by inunda-
tion of the land with several inches of effluent.
Descriptions of the various flooding techniques are
contained in Wastewater Treatment and Reuse by Land
Application 5. The depth of applied effluent and period
of flooding are dependent on the characteristics of the
soil and the crop grown. The technique is well suited
to irrigation of grasslands.
Infiltration-Percolation
In this method, effluent is applied to the soil by
spreading in basins or by spraying, and is treated as it
travels through the soil matrix. Vegetation is generally
not employed although there are some exceptions.
Preapplication treatment is generally provided to
reduce the suspended solids content and thereby allow
the continuation of high application rates. Secondary
treatment is often provided prior to spreading or
ponding although primary treatment effluent has also
been used.
Site Characteristics — Because most of the applied
effluent percolates through the soil, soil drainage is
usually the limiting site characteristic. Other site
evaluation criteria include:
• Climate — Infiltration-percolation is applicable
to nearly all climates. Loadings may need to be
reduced for cold weather conditions.
• Topography — Level terrain is preferable, but
rolling terrain is acceptable.
• Soil type — Acceptable soils include sand, sandy
loams, loamy sands, and gravels. Soils that are
too coarse provide insufficient renovation.
• Soil drainage — Moderate-to-rapid drainage is
preferable.
• Soil depth — Uniformly 10 to 15 feet of soil depth
is preferred.
15
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RAIN DROP ACTION-
wl®K*j&totm*tt
',
-------
• Geologic formations — Lack of significant discon-
tinuities is necessary.
• Groundwater — A minimum depth of 15 feet to
the existing water table is necessary; it should not
be allowed to rise to less than 4 feet from the
ground surface. Control by underdrains may be
required.
Infiltration-Percolation Techniques — Spreading and
spraying are two application techniques suitable for
infiltration-percolation. Spreading using basins is the
most common technique. Spreading can usually be
continued through freezing weather if underground
piping is used. Multiple basins are generally used and
periods of flooding are alternated with periods of dry-
ing-
Application by spraying is less common to
municipal systems being found mostly in industrial
systems. Normally, vegetation such as hydrophytic
grasses is used to protect the soil surface from the im-
pact of the spray droplets and maintain the high in-
filtration rates.
Overland Flow
In this method, wastewater is sprayed over the up-
per reaches of sloped terraces and allowed to flow
across the vegetated surface to runoff collection
ditches. Renovation is accomplished by physical,
chemical, and biological means as the wastewater
flows in a sheet through the vegetation and litter.
Preapplication treatment should include removal of
large solids, grit, and grease that hamper effective
spraying. The renovation noted in Table 1 has been
shown for domestic as well as industrial wastewaters.
For domestic wastewater that is not adequately dis-
infected prior to overland flow treatment, disinfection
of the collected runoff may be necessary.
Site Characteristics — Important site characteristics in-
clude:
• Climate — Warm climates are preferable, but
more severe climates are acceptable if adequate
storage is provided for freezing conditions.
ENGINEERING
Factors that affect the engineering design of land
application systems include (1) climatic conditions,
(2) wastewater quality, (3) crops or vegetation, and
(4) the hardware involved in applying the wastewater.
These factors affect each of the three basic treatment
methods differently. For example, climatic conditions
are more critical for irrigation than for infiltration-
percolation. Consequently in a thorough discussion of
these factors, which is not possible here, each type of
system should be addressed separately.
Climatic Factors
Local climatic conditions will affect decisions as to
the method of application, storage requirements, and
• Topography — Rolling terrain is well suited;
level terrain can be graded to create uniform
slopes of 2 to 6 percent.
• Soil type — Clays and clay loams are preferable.
• Soil drainage — Poor or slow drainage is
preferable.
• Soil depth — Six to 8 inches of good topsoil is
needed.
• Geologic formations — Lack of major discon-
tinuities is necessary.
• Groundwater — Groundwater should not in-
terfere with plant growth.
Overland Flow Techniques — Spraying is the common
application technique for overland flow using fixed
sprinklers or rotating boom-type sprays. Application
by flooding or other surface techniques in overland
flow systems has not been demonstrated in this coun-
try, but it has been practiced successfully in
Melbourne, Australia. If high concentrations of
suspended solids are present, settling in the upper
reaches may cause an odor problem. Because uniform
distribution is critical, flooding may not be successful
unless care is taken to produce an extremely smooth
terrace with no noticeable depressions.
Combinations of Methods
Combinations of land application techniques may
be desirable when dealing with problems of differences
in site characteristics (either within one large site or
between a number of sites), seasonal weather
variations, or limiting water quality criteria. They
may also be useful in adapting land application to pre-
sent land use; for instance, using a portion of the
wastewater to irrigate an existing golf course. The
selection of the type of system or combination of
systems to be designed should result from a thorough
analysis of the treatment objectives, site and
wastewater characteristics, and the available land
application technology.
DESIGN CRITERIA
acceptable loading rates. Important climatic factors
include precipitation amounts and intensities,
temperature, evapotranspiration, and wind.
Precipitation — The annual quantity and seasonal dis-
tribution of precipitation is important to the design of
distribution and storage systems. Periods of intense
precipitation or snow cover may prevent effluent
application and require storage. Wetter-than-normal
years should be used in the analysis of the storage re-
quirements and in the conduct of the water balance.
Temperature — An analysis of temperature variations is
useful in selecting the type of land application method
17
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and in estimating periods of nonoperation. Maximum
periods of freezing and number of days where the high
temperature remains below a certain value, say 25
degrees F for example, are important in design.
Evapotranspiration — Along with percolation and runoff,
evapotranspiration represents a major part of the
water loss portion of the water balance. Where
evapotranspiration rates exceed precipitation, as they
often do west of the Mississippi, the concentrating
effect on the dissolved solids in the effluent applied
should be considered. Temperature, wind, and
relative humidity also influence evaporation rates.
Wind — Wind directioin and velocity are important in
the design of sprinkling systems. High winds can
cause uneven distribution of spray patterns. Systems
designed for overlap during winds of 10 mph should
have laterals spaced at 50 percent of the -spray
diameter3.
Wastewater Quality
Important wastewater characteristics include con-
stituents listed in discharge requirements, as well as
constituents that can affect the efficiency of system
operation. The importance and acceptable loadings of
organic matter and inorganic constituents will be dis-
cussed.
Organic Matter — Organic matter includes BOD and
COD as well as persistent, trace organics. The soil is a
highly efficient biological treatment system; therefore,
liquid loading rates at land treatment operations are
normally governed by the hydraulic capacity of the
soil rather than the organic loading rate. This
operational independence from BOD loading is a dis-
tinct advantage of land treatment systems over con-
ventional in-plant systems in treating high-strength
wastewaters, particularly industrial wastes. There are
limits, of course, to the organic loading that can be
placed on the land without stressing the ecosystem in
the soil. The effects of organic overloads on the soil in-
clude damage to or killing of vegetation, severe clog-
ging of the soil surface, and leaching of undegraded
organic material into the groundwater.
Defining the limiting organic loading rate for a
system must be done on an individual basis. However,
rule of thumb rates have been developed based on ex-
perience. Thomas6 cites 25 Ib/acre/day as a loading
rate at which decomposition will approximately
balance organic matter accumulation. For infiltration-
percolation systems, a maximum BOD loading rate of
200 Ib/acre/day has been suggested as the safe
loading rate for pulp and paper wastewaters7.
Substantially higher loading rates (greater than 600
Ib/acre/day) have been used on a short term seasonal
basis for infiltration-percolation systems. For overland
flow systems, organic loadings in the range of 40 to
100 Ib/acre/day have been successfully used5.
Inorganics — Dissolved inorganic constituents are those
with the broadest impact on land treatment systems.
They include TDS, nitrogen, phosphorus, ex-
changeable cations, and trace elements.
TDS - The TDS content, which is related to the EC
(electrical conductivity) is generally more important
than the concentration of any specific ion. Unless
proper irrigation management is practiced, high TDS
wastewater can cause a salinity hazard to crops, es-
pecially in arid and semiarid areas. Salt buildup in the
groundwater as a result of irrigation with effluent may
limit large-scale use in some hydrologic basins.
Nitrogen — Nitrogen can be removed in soil treatment
systems by crop uptake and harvest or by denitrifica-
tion. Crop uptake is the major removal mechanism in
irrigation and can account for 50 to 600 Ib/acre/year
of nitrogen depending on the crop and yield.
Denitrification may be significant for overland flow
and infiltration-percolation systems depending on the
hydraulic and organic loadings and the creation of
anaerobic conditions 8 9 - 'All nitrogen forms interact
within the soil but the nitrate form is mobile and can
pass through the soil to the groundwater.
Phosphorus — Phosphorus contained in wastewater oc-
curs mainly as inorganic compounds, primarily
phosphates, and is normally expressed as total
phosphorus. Phosphorus removal is accomplished
through plant uptake and by fixation in the soil
matrix10. Long term loadings of phosphorus are im-
portant because the fixation capability of some soils
may be limited over the normal expected life span of
the system. Phosphorus that reaches surface waters as
a result of surface runoff or interception of
groundwater flow may aggravate problems of
eutrophication.
Exchangeable cations — Exchangeable cations, par-
ticularly sodium, calcium, and magnesium ions
deserve special consideration. High sodium concen-
trations in clay-bearing soils have the effect of dispers-
ing the soil particles and decreasing the soil
permeability. To determine the sodium hazard, the
sodium adsorption ratio (SAR) has been developed by
the U.S. Department of Agriculture Salinity
Laboratory11. High SAR (greater than 9) values may
adversely affect the permeability of soils12. Other ex-
changeable cations, such as ammonium and
potassium may also react with soils. Occasionally high
sodium concentration in soil can also be toxic to
plants, although the effects on permeability will
generally occur first.
Trace elements — Although many trace elements are es-
sential in varying degrees for plant growth, some
become toxic at higher levels to both plant life and
microorganisms. Retention of trace elements such as
18
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heavy metals in the soil matrix is by adsorption and
ion exchange, although removal of metals from solu-
tion by precipitation does occur to some extent, es-
pecially in the presence of sulfides. Retention
capabilities are generally good for most metals in most
soils, especially for pH values above 7. Under low pH
conditions, metals can be leached out of soil systems.
Boron is another trace element that may be toxic to®
certain plants at concentrations above 0.5 mg/1.
Crops/Vegetation
Crops or vegetation to be planted may be selected
based on various factors: high water and nutrient up-
take, such as for hydrophytic grasses; high salt
tolerance (bermuda grass); high market value, such as
alfalfa or corn; or low management requirements.
When the crop is selected for its high market value, a
careful analysis must be made of the wastewater to en-
sure that no constituents are present in concentrations
that would affect the yield expected. Perennial grasses
with market potential are generally favored for land
application systems.
System Components
A land application system may be composed of a
number of distinct components from the following
categories:
• Preapplication treatment
• Transmission
• Storage
• Distribution
• Recovery of renovated water
• Monitoring
Typical distribution systems for the major types of
land application will be described and design criteria
will be discussed. These systems include solid set
spraying, center pivot spraying, spreading basins, and
overland flow using solid set spraying. Design criteria
for other system components are discussed in Evalua-
tion of Land Application Systems1*.
Solid Set Spraying (Buried) — Solid set spraying using
buried pipe is used primarily for spray irrigation
systems, but it may also be used for infiltration-
percolation and overland flow systems. The major
design variables include: sprinkler spacing, applica-
tion rate, nozzle size and pressure, depth of buried
pipe, pipe materials, and type of control system. For
more detailed information, additional references, such
as Sprinkler Irrigation*, should be consulted.
• Sprinkler spacing — May vary from 40 by 60 feet
to 100 by 100 feet and may be rectangular,
square, or triangular. Typical spacings are 60 by
80 feet and 80 by 100 feet.
• Application rate — May range from 0.16 to 1
in./hr, with 0.2 to 0.25 in./hr being typical.
Weekly rates vary with climate, soil type, and
crop requirements over the ranges indicated in
Table 1.
• Nozzles — Generally vary in size of openings
from 0.25 inch to 1 inch. The discharge per nozzle
can vary from 4 to 100 gpm with a range from 8 to
25 gpm being typical. Discharge pressures can
vary from 30 to 100 psi, with 50 to 80 psi being
common.
• Depth of buried laterals and mainlines — Depen-
dent on the depth of freezing for cold climates.
Where the depth of freezing is not a factor, a
depth of 18 inches for laterals, and 36 inches for
mainlines is common2. Surface piping, usually of
aluminum, may be 40 to 50 percent less costly
than buried piping, but it is also less durable.
• Pipe materials — Any type of standard pressure
pipe may be used; however, asbestos-cement and
plastic (PVC) pipe are most common. Factors
that should be considered when selecting type of
pipe material include: cost, strength, ease of in-
stallation, and reliability.
• Control systems — May be automatic,
semiautomatic, or manual. Automatic systems
are the most popular for land application
systems. Automatic valves may be either
hydraulically or electrically operated.
Center Pivot Spraying — Center pivot spraying systems
are most commonly designed to irrigate areas ranging
from about 35 to 135 acres per unit. Units may be
driven electrically, hydraulically, or mechanically,
and may be designed to complete one revolution in a
period ranging from 8 hours to as much as 1 week.
Standard operating pressure is generally 50 to 60 psi.
More detailed information can be obtained from the
supplement to the third edition of Sprinkler Irrigation2.
Infiltration Basins - This method is the most common
for infiltration-percolation systems. The major design
variables include: application rate, basin size, height
of dikes, and maintenance of basin surfaces.
• Application rates — Can vary from 4 to 120
in./wk, with the range of 12 to 24 in./wk being
most common. Loading cycles generally vary
from 9 hours to 2 weeks of wetting with 1 day to 3
weeks of drying.
• Basin size — Generally a function of design flow
and relationship of wetting and drying periods.
Basins may range in size from less than 1 acre to
around 50 acres. It is usually necessary to include
at least 2 separate basins for even the smallest of
systems.
• Height of dikes — Will vary with depths of water
applied. For depths of 1 to 2 feet, a height of dikes
of approximately 4 feet is common.
• Maintenance of basin surface — May be a signifi-
cant operation and maintenance expense. Many
19
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systems require periodic tilling of surface, often
annually, while some high-rate systems may re-
quire periodic replacement of sand or gravel.
Overland Flow — The most common method of
application for overland flow systems is solid set
spraying using buried pipe. Consequently, most of the
ranges of design variables discussed for solid set spray-
ing are applicable; the most significant difference is
sprinkler spacing. Lateral spacing is determined by
terrace width, which may range from 150 to 300 feet.
Sprinkler spacing along laterals may range from 40 to
80 feet. The terraces, which are an integral part of the
distribution system, may range in slope from 2 to 6
percent. The most common hydraulic loading cycles
are 6 to 8 hours of wetting and 16 to 18 hours of dry-
ing, depending on climate and time of year5.
CASE STUDY
To illustrate the general design considerations that
have been presented, a case study of a preliminary
land application system design will be discussed. A
discussion of the background and preliminary
engineering functions will precede the analysis of the
available alternatives.
Background
Metcalf & Eddy, Inc., was recently retained by the
Baltimore District, Corps of Engineers, to design a
land application system for Fort George G. Meade,
Maryland. Fort Meade is located between Baltimore
and Washington, D.C., near the Balti-
more/Washington International Airport. Because the
contract for services was issued after the first of
November, 1974, the work on design concepts and
parameters has only recently begun. However, the
project has a number of interesting facets and will
serve to illustrate how combinations of land applica-
tion methods can be utilized in design.
A preliminary engineering report was prepared and
submitted to the Corps in June, 197314, in which im-
plementation of spray irrigation as the means of liquid
wastewater disposal was recommended. A recon-
naissance level study of the available lands defined the
limits of the area that would be suitable for receiving
an effluent application rate of 2 inches per week. The
land treatment system was to include an aerated
lagoon, a storage lagoon, chlorine contact tank, pump-
ing station, sprinkler irrigation system, and an ad-
ministration building. Secondary clarifiers and an
aerobic digester were also proposed for solids capture
and treatment.
The site selected for effluent irrigation is shown in
Figure 3. The site is bounded on the south and west by
the Little Patuxent River, on the north by a railroad
and warehousing complex, and on the east by several
firing ranges. Also, located at the northwest corner is
the Tipton Army Airfield, which serves the smaller
aircraft associated with the post. One additional im-
portant feature is Soldiers Lake, a small, manmade
lake located in the northeast corner of the site. This
lake provides some leisure-time fishing for the military
personnel.
Site characteristics of special interest to land treat-
ment are summarized as follows:
• • Land area — 725 acres
• Elevations — 120 to 225 feet
• Slopes —
overall, 0 to 12 percent
average, 5 to 10 percent
• Vegetation —
regrowth of pine, 30 percent older pine and
hardwoods, 70 percent
• Soils — loamy sands to clay loams
A major part of the site is presently being used as an
impact area for small arms ranges. These ranges are
heavily used, especially during the summer and fall
months, and there are no plans for relocating the
ranges. This site characteristic is obviously not a nor-
mal design parameter for an effluent irrigation system.
It does, however, dictate that special consideration be
given to selection of hardware, pipeline location,
pipeline materials, operational procedures, and
remote controls.
Another major consideration in the design of
sewage treatment and disposal facilities is the dis-
charge quality criteria. Recent meetings between the
USEPA, Region III; Baltimore District, Corps of
Engineers; U.S. Army Environmental Hygiene Agen-
cy; Maryland Water Resources Administration; and
Maryland Environmental Health Administration
resulted in several conclusions. The conclusions are
summarized in Table 2.
Table 2. SUMMARY OF APPLICABLE WATER
QUALITY CRITERIA
Quality prior to land application
Secondary treatment and disin-
fection
BOD
30-day mean
7-day mean
Total coliform bacteria
Quality of groundwater
Natural groundwaters below
the site
Seepage or groundwater under-
flow to Little Patuxent River
Total nitrogen (N)
Total phosphorus (P)
Total coliform bacteria
<30mg/l
<45mg/l
^3 colonies/100 ml
<1962 PHS drinking water
standards
<3mg/r
^8mg/l'a
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FIGURE 3. SITE PLAN FOR LAND TREATMENT SYSTEM
21
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preliminary report. At that time, effluent quality re-
quirements were as follows:
BOD
Ammonia nitrogen (N)
Organic nitrogen (N)
Dissolved oxygen
£10 mg/1
^1.0 mg/1
£1.0 mg/1
2:4.0 mg/1
Nitrification was required by these criteria, but sub-
sequent correspondence (1973) with the Maryland
Water Resources Administration resulted in an in-
dication that both nitrogen and phosphorous removals
may soon be required for discharge to water bodies of
the Patuxent River Basin. For this reason, an ad-
vanced wastewater treatment plant, including
nitrification and denitrification, was the alternative to
a land treatment system.
The available raw wastewater characteristics and
the present and projected flows are summarized in
Table 3.
Table 3. RAW WASTEWATER
CHARACTERISTICS (14)
Parameter
Value
Flowrate, mgd
Present average (1973)
Design average (2000)
BOD, mg/1
Total nigrogen (N), mg/1
Total phosphorus (P), mg/1
Suspended solids, mg/1
Total solids, mg/1
2.9
4.6
160-235
22-34
9.0-10.9
152-392
490-810
Preliminary Engineering Functions
Having developed the background to the problem,
the actual work of engineering can be described.
Because the work has not yet been accomplished, firm
results and conclusions cannot be presented.
However, a general description of the tasks that have
either been initiated or will be performed during the
program are discussed in the following paragraphs.
Soil Survey — A soil survey was performed by the Soil
Conservation Service during August, 1974, for the
Baltimore District, Corps of Engineers and the report
was submitted October 15, 1974. The study was keyed
to the existing Soil Survey of Anne Arundel County,
Maryland, issued in 1973. A summary of the major
soil limitations mapped in that report is shown in
Figure 4. One purpose of this survey was to define the
infiltration capacity of the various soils.
Geological Investigation — This work was started in the
field on November 4, 1974, and should be completed
by January, 1975. The work is being done by the
Geology and Foundation Section, Baltimore District,
Corps of Engineers. Two objectives are to be ac-
complished under this program. The first is to develop
a detailed description of the site geology, showing
detailed lithology in at least two sections. Special note
is to be made of fault zones, fracture trace intersec-
tions, open bedding planes, or any other discon-
tinuities. Also a good picture of the underlying
groundwater contours is to be developed. The second
objective is to establish a series of monitoring wells in
coordination with their drilling and exploration
program. These wells are to be suitable for both
baseline quality data and also Tor a continuing
monitoring program.
Monitoring Program — The U.S. Army Environmental
Hygiene Agency is performing a sampling and testing
program in conjunction with the Baltimore District,
Corps of Engineers and the Post Facilities Engineer.
They have assisted in defining and coordinating the
program to date and will continue through the design
and construction phase of the project. There is a
possibility that CRREL (Cold Regions Research and
Engineering Laboratory) may become the lead agency
;n this area after startup.
Climatic Data — Data are available from both the
records of Fort Meade and the U.S. Weather Bureau
Station at the Baltimore/Washington Airport. The
data are now being compiled and analyzed by Metcalf
& Eddy to develop a water balance and to determine
storage requirements. The climatic parameters
assumed initially as being applicable are:
Precipitation
• Wettest year in 10 — 51.0 in./yr
• Average annual — 41.4 in./yr
• Number of days with precipitation over
0.1 inch —
per year, 74 days
per month, 8 days
Evapotranspiration
• Average annual — 30 in./yr
Temperature
• Number of days that temperature remains below
32 degrees F —
per year, 14 days
per month, 6 days
Wind Velocity
• Number of days per month that wind velocity
exceeds 15 mph
Water Balance — From the climatic data, the number of
days that the spray system would probably not
operate can be estimated. From the data on infiltra-
tion estimates, precipitation, evapotranspiration, and
wastewater flows, an annual water budget will be
developed. The results of these data will be used to es-
timate the land area required for the design
wastewater flow, unless limited by some other
parameter.
22
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FIGURE 4. SOIL INFILTRATION RATES FOR LAND TREATMENT SITE
23
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Nutrient Balance — Based on the amount of available
nutrient in the wastewater, the amount of nutrient
removal that may be expected from the vegetative
cover or treatment method, and the allowable effluent
quality criteria, the land area developed from a water
balance must be checked. If the nutrient removal
capacity is inadequate, then additional land must be
added or the treatment method must be changed.
Preparation of Construction Plans — After the water
balance and nutrient balance (or balance for any other
wastewater constituent that may prove critical) have
been completed and the land area selected, the
physical system can be designed.
Alternative Treatment Plans
Although all necessary data are not available at this
time, there are sufficient data to make a preliminary
assessment of the suitability of various land treatment
methods or combinations of methods. The most
critical parameters are the following:
2100
• Hydraulic loading (water to be treated)
• Nitrogen removals
• Operating time—suggested by owner (40 hr/wk)
established by climatic conditions
• Soil characteristics
• Vegetative cover
• Available land area
All three basic land treatment methods are being
considered, including (1) spray irrigation, (2) over-
land flow followed by additional treatment and/or
disposal, and (3) infiltration-percolation followed by
spray irrigation. Seven alternatives were developed
from these methods for review and they are listed in
Table 4.
Table 4. LAND APPLICATION ALTERNATIVES
AT FORT MEADE
1. Spray irrigation of woodlands
2. Spray irrigation of grasslands
3. Spray irrigation of a combination of grass and wooded
lands
4. Overland flow followed by direct discharge to Little Pa-
tuxent River
5 Overland flow followed by spray irrigation of woodlands
6. Overland flow followed by infiltration-percolation with
withdrawal and discharge to the river
7. Infiltration-percolation and pumped withdrawal followed by
irrigation of grasslands
Note All of the above alternatives would be preceded by
aerated lagoon, storage lagoon, and disinfection, if
necessary.
Spray Irrigation — There are 3 alternatives involving
spray irrigation as the treatment and disposal method.
Alternative 1 involves spray irrigating the existing pine
and hardwood forest. Based on the nitrogen uptake of
forests observed at Penn State15, a removal of ap-
proximately 100 Ib/acre/yr of nitrogen can be ex-
pected. When 4.6 mgd of effluent containing 25 mg/1
of total nitrogen is applied over 700 acres of land, the
resulting areal loading is 500 Ib/acre/yr of nitrogen. If
100 Ib/acre/yr is removed, the remaining 80 percent
of the nitrogen applied will ultimately reach the
groundwater at a concentration of 20 mg/1, mostly as
nitrate-nitrogen. Because this exceeds the discharge
standards, Alternative No. 1 should be rejected.
If 10 mg/1 is the maximum nitrogen permissable in
the groundwater, there must be a 60 percent or more
reduction of the nitrogen applied. In other words, a
vegetative cover must be found that will take up ap-
proximately 300 Ib/acre/yr of nitrogen. Reed canary
grass was found at Penn State to satisfy this goal15 and
other grasses are probably available. Nearly the entire
site would have to be cleared and planted to grass for
Alternative No. 2 to meet the nitrogen loading. The
actual area required would be 640 acres, based on a
nitrogen uptake of 400 Ib/acre/yr. Consequently,
Alternative No. 3, with irrigation of a combination of
grass and forested areas does not appear practical
because there would be little, if any, forested area
remaining.
Overland Flow — Pilot scale work using municipal
wastewater (reported by Thomas16) and bench scale
work (reported by Hoeppel, et al.17) have been con-
ducted for overland flow treatment. Nitrogen removals
reported in these studies are consistently 80 to 85 per-
cent and more. Results of full scale operations reflect
these same high removals18. The effluent in these
studies was highly nitrified, which would be accep-
table for discharge under the 1973 standards. Under
requirements of 90 percent nitrogen removal, however,
overland flow alone should not be relied on to meet the
discharge criteria, consequently Alternative No. 4 is
not considered viable.
Alternative No. 5, in which overland flow would be
followed by spray irrigation, and Alternative No. 6, in
which it would be followed by infiltration-percolation
and discharge to surface waters are considered viable.
In Alternative No. 5, a loading rate of 0.7 in./day is
used to establish the land requirement. This area is
then increased to allow time for nonoperation during
freezing weather and during crop harvest. The field
area required for overland flow is 400 acres. Because
the upper portions of the site exhibit the less
permeable loamy and clayey soils, this area would be
utilized for overland flow. The remaining area would
be kept as forest, except for installation of spray lines
and roads.
In Alternative No. 6 the spray irrigation component
would be replaced with infiltration-percolation. As in
Alternative No. 5, approximately 30 percent of the
water applied to the overland flow system would be
24
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lost to percolation and the remaining 3.2 mgd would
be collected. This renovated effluent would then be
spread in infiltration-percolation basins, covering 80
acres of the most permeable soils. After renovation by
the soil, the water would be pumped out and dis-
charged to surface waters. In effect, the infiltration-
percolation process would be used as a polishing filter.
The quality of the renovated water should exceed the
discharge requirements.
Infiltration-Percolation — Alternative No. 7 would in-
volve infiltration-percolation of secondary effluent
followed by pumped withdrawal and spraying of
renovated water on grassland for disposal. Based on
work by Bouwer19 at Flushing Meadows, Arizona, a
well managed infiltration-percolation system can at-
tain 30 percent nitrogen removal. The combination of
natural filtration that would greatly reduce BOD,
suspended solids, and coliforms, followed by spray
irrigation for nitrogen removal by plant uptake could
be feasible for this project. Because of the 30 percent
reduction in nitrogen loading, the area required for
spray irrigation would be reduced to 450 acres. The
land area required for the infiltration-percolation
system would be 170 acres, based on an application
rate of 7 in./wk.
Cost Comparison of Alternatives
On the basis of this cursory review of the available
alternatives, three were screened as not being viable.
The remaining four alternatives are listed in Table 5
along with the estimated capital costs. The cost es-
timates are very rough and do not include such items
as preapplication treatment, piping to the land
application site, roads, or allowances for contingen-
cies, administration, or engineering. The costs do in-
clude storage, site clearing, distribution systems,
pumping, and collection of renovated water. The costs
are indexed to the EPA Sewer Construction Index for
July 1974 in Baltimore. The basis of this cost com-
parison is a draft report prepared by Metcalf & Eddy,
Inc., on Costs of Land Application Systems1, which is un-
dergoing review by the Environmental Protection
Agency. Operation and maintenance costs, for which
cost curves are also included in the EPA report, are
not included here.
The selection of the best alternative will be based on
the results of a cost-effectiveness analysis, the ability to
meet the water quality criteria, and considerations of
land use and impacts on the environment. As the
detailed aspects of each alternative are considered,
refinements and modifications that affect the costs
probably will occur. In addition to the soils informa-
tion previously described, more detailed data on the
geology and soil profile may be required for the areas
selected for infiltration-percolation.
Table 5. PRELIMINARY COST COMPARISON
OF LAND APPLICATION ALTERNATIVES AT
FORT MEADE
Alternative
No.
Description
Construction
cost,
S(millions)
2 Spray irrigation of grass- 2.75
lands
5 Overland flow followed 2.69
by spray irrigation of
woodlands
6 Overland flow followed 1.95
by infiltration-percola-
tion with discharge to
the river
7 Infiltration-percolation 2.40
followed by spray irri-
gation of grasslands
Note: Costs are for July 1974 and do not include land, piping
to the site, pretreatment, contingencies, or engineering.
CONCLUSION
A brief review of the various land application
methods was presented including some of the
engineering criteria that serve to differentiate the
methods. A preliminary analysis of an actual case
study was included to illustrate how the different land
application methods can be combined to overcome
restrictions in topography, soil permeability, and
water quality criteria. It is important that the engineer
dealing with land application of effluents does not
attempt to transfer the operational features and design
parameters from another geographical area to his
specific case without giving consideration to all of the
different conditions. Land treatment methods should
be considered as unit processes in much the same way
as sanitary engineers have long considered the various
conventional treatment processes. The various treat-
ment methods should be selected or combined in such
a way as to provide a design that is tailored to the
specific site and its limitations.
25
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REFERENCES
1. Pound, C.E., R.W. Crites, and D.A. Griffes. Costs
of Land Application Systems. Office of Water
Program Operations, Environmental Protection
Agency. November 1974. (Preliminary Draft).
2. Pair, C.H., (ed.). Sprinkler Irrigation. Supple-
ment to the 3rd Edition. Silver Spring, Sprinkler
Irrigation Association. 1973.
3. Pair, C.H. (ed.). Sprinkler Irrigation, 3rd
Edition. Washington, D.C., Sprinkler Irrigation
Association. 1969.
4. Sprinkler Irrigation. Irrigation, Chapter 11. SCS
National Engineering Handbook, Section 15. Soil
Conservation Service. U.S. Department of Agri-
culture. July 1968.
5. Pound, C.E., and R.W. Crites. Wastewater
Treatment and Reuse by Land Application —
Vol. II. Office of Research and Development.
Environmental Protection Agency. August
1973.
6. Thomas, R.E. Fate of Materials Applied. Con-
ference on Land Disposal of Wastewaters.
Michigan State University. December 1972.
7. Blosser, R.O., and E.L. Owens. Irrigation and
Land Disposal of Pulp Mill Effluents. Water and
Sewage Works. Ill, No. 9. pp 424-432. 1964.
8. Lance, J.C. Nitrogen Removal by Soil Mech-
anisms. Journal WPCF. 44, No. 7. pp 1352-1361.
1972.
9. Sepp, E. Nitrogen Cycle in Groundwater. Bureau
of Sanitary Engineering. California Department
of Health. Berkeley. 1970.
10. Reed, S.C. Wastewater Management by
Disposal on the Land. Corps of Engineers,
U.S. Army, Special Report 171. Cold
Regions Research and Engineering Laboratory,
Hanover, New Hampshire. May 1972.
11. U.S. Salinity Laboratory. Diagnosis and Improve-
ment of Saline and Alkali Soils. Agricultural
Handbook No. 60. U.S. Department of Agri-
culture. 1963.
12. Ayers, R.S. Water Quality Criteria for Agricul-
ture. UC-Committee of Consultants. CWRCB.
April 1973.
13. Evaluation of Land Application Systems.
Office of Water Program Operations, Environ-
mental Protection Agency. September 1974.
(Draft).
14. Baker-Wibberley & Associates. Report on Alter-
nate Methods of Sewage Disposal at Fort George
G. Meade, Maryland. Departmen of the Army,
Baltimore District, Corps of Engineers. June
1973.
15. Kardos, L.T. et al. Renovation of Secondary
Effluent for Reuse as a Water Resource. Office of
Research and Development, Environmental Pro-
tection Agency. February 1974.
16. Thomas, R.E. Spray-Runoff to Treat Raw
Domestic Wastewater. International Confer-
ence on Land for Waste Management. Ottawa,
Canada. October 1973.
17. Hoeppel, R.E., P.G. Hunt, and T.B. Delaney, Jr.
Wastewater Treatment on Soils of Low Permea-
bility. U.S. Army Engineer Waterways Experi-
ment Station, Vicksburg, Mississippi. July 1974.
18. C.W. Thornthwaite Associates. An Evaluation of
Cannery Waste Disposal by Overland Flow Spray
Irrigation. Publications in Climatology, 22, No. 2.
September 1969.
19. Bouwer, H., R.C. Rice, and E.D. Escarcega.
Renovating Secondary Sewage by Ground Water
Recharge with Infiltration Basins. U.S. Water
Conservation Laboratory, Office of Research and
Monitoring. Project No. 166060 DRV. Environ-
mental Protection Agency. March 1972.
26
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Public Health Aspects of Land Application of Wastewater Effluents
by
Charles A. Sorber
U.S. Army Medical Bioengineering Research & Development Laboratory
Fort Detrick, Frederick, Maryland
INTRODUCTION
The goal of land treatment is the treatment of
wastewater in an economically, socially and en-
vironmentally acceptable manner to produce high
quality renovated water while concurrently producing
useable crops.
The environmental and public health aspects of
recycling municipal wastewaters on the land are
dependent upon a number of variables. One impor-
tant variable is the ultimate use of the partially
renovated wastewater. Uses may include discharge to
a surface body with or without percolation through
the soil; groundwater recharge; crop irrigation; and,
obviously, any combination of the three.
The method of application of the wastewater is
another important variable. Of primary interest are
the overland flow, rapid infiltration and spray irriga-
tion application methods, each of which has distinct
requirements with respect to soil character, crop cover
and application rate. Selected characteristics of
several land application systems can be found in Table
1.
In general, the basic environmental and public
health considerations will be similar, despite the con-
ditions of wastewater ultimate use, pretreatment and
application technique. However, once a set of design
variables are selected, emphasis must be placed on
those concerns which are most critical to the selected
variables.
In a discussion of this nature, due consideration
must be given to the physical, biological and chemical
aspects of the problem.
Table 1. SELECTED CHARACTERISTICS OF LAND APPLICATION SYSTEMS
System
Factor
Application rate
Land required for Imgd flow (net)
Desired soil permeability
Probability of influence on ground water
Evaporation
Treatment effectiveness
Overland
Flow
8-15ft/yr
75-140 acres
Low
Slight
(20%)
20%
Moderate
Rapid
Infiltration
1 5-400 ft/yr
3-75 acres
High
Certain
(90%)
10%
• Low
Spray
Irrigation
2-8 ft/yr
140-560 acres
Moderate
Probable
(70-30%)
30-70%
High
PHYSICAL CONSIDERATIONS
Physical considerations of land application of
wastewaters are somewhat secondary, in that they
relate, to a large degree, to both the biological and
chemical considerations. Particular attention must be
paid to the removal of suspended material which will
insure that both the distribution system and the soil
treatment system do not become clogged. The
physical characteristics of the soil treatment system
are infinitely important. Wide variations in soil
characteristics make it mandatory that each potential
land application site be studied intensely before land
application practices are instituted. As will be
developed shortly, the physical characteristics of the
soil and the application system are intimately related
to both the biological and chemical aspects of
municipal wastewater land application.
"The opinions or assertions contained herein are the private views of the author and are not to be construed as official or as reflecting the views of the Department
of the Army or the Department of Defense."
27
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BIOLOGICAL CONSIDERATIONS
With regard to the biological considerations,
pathogens in wastewater represent one of the major
potential health problems associated with recycling
municipal wastewaters on the land. This problem can
manifest itself in two ways: contamination of
groundwaters used for public water supply and dis-
semination of pathogenic aerosols which may be in-
haled by man or animals in or near the application
site. (Sorber, 1973)'.
Pathogen Concentrations in Wastewaters
The number of pathogens found in municipal
wastewaters varies widely depending on the time of
year and the community. For example, estimates of
virus concentrations from field studies have indicated
concentrations up to 7000 plaque forming units
(PFU/liter for raw sewage to about 50-1600 PFU/liter
for chlorinated secondary effluents. (Sorber, et al.,
1972)2. In fact, recently, Buras (1974)3 found an
average of 56,000 PFU/liter in secondary effluent by
using her direct inoculation technique.
It has been demonstrated repeatedly that many
pathogens, especially viruses, pass conventional waste
treatment processes even though they have been
reduced in number. As Berg (1973)4 accurately points
out, primary and secondary treatment processes
reduce the numbers of viruses only slightly. Although
some laboratory studies have shown good results, field
evaluations are, at best, erratic.
In actual practice, disinfection probably plays the
most important role in reducing pathogen concen-
trations in wastewater. However, much of the classical
data on disinfection does not resemble real world con-
ditions. Disinfection as practiced in wastewaters is
often far less effective for pathogens, especially viruses,
than it is for indicator bacteria. Table 2 contains re-
cent field data which affirms this contention.
Pathogens in Soils
The application of wastewater to soil has been
studied to some extent with regard to pathogen
mobility and destruction in soils (Sorber, et al., 1972)5.
Basically, pathogen removal in soils is a function of the
characteristics of the soil. Under certain conditions,
such as limestone crevicing, pathogens have been
found to travel miles. On the other hand, heavily tex-
tured clay soils, thru adsorption and filtration, can
remove viruses, bacteria and the larger pathogens, on
and near the soil surface.
Those pathogens which are collected on or in soil
can be inactivated after land application. Exposure to
ultraviolet light, oxidation, desiccation and an-
tagonistic soil organisms are the most important
destructive mechanisms. Conversely, there is ample
literature citation to indicate that some pathogens can
survive these deleterious effects in soil for relevantly
long periods.
It has been shown that coliform organisms do not
Table 2. EFFECT OF WASTEWATER
TREATMENT ON VARIOUS ORGANISMS
(After Sorber, et al, 1974)5
Total Reduction Reduction by
in Treatment Chlorination
Plant (Log,0) Only (Log,0)
PL ANT #1*
Fecal Coliform
Fecal Streptococci
Salmonella \
Enteric Viruses If
PLANT #2 S
Total Coliform
Fecal Coliform
Klebsiella a
f2 Bacteriophage
3.7
2.4
1.4
0.4
6.8
5.8
5.2
2.1
2.0
0.5
0.3
5.5
3.6
3.7
0.9**
* Standard-rate trickling filter; chlorine residual approximately
1.5 mg/1.
f Presumptive. M-bismuth sulfite broth with MF procedure.
If Three days on BGM cells after concentration (Schaub and
Sorber, 1974)6.
6 High-rate trickling filter; chlorine residual approximately 4
mg/1 with improved mixing.
a Large number confirmed as Klebsiella on differential media.
** After Kruse, et al. (1973)7.
survive in soil and on vegetation as long as certain
other bacteria such as salmonella, klebsiella, and some
worm eggs. Virus survival on soil is essentially unex-
plored. It is likely, however, that viruses will survive
longer than coliform organisms. It is important to
know whether pathogenic organisms can survive on
soil and vegetation for extended times.
It is also important to consider pathogen concentra-
tion on or near the soil surface. Consideration should
be given to the effects of long term application of non-
degradable organic materials that may clog the soil
surface or tie-up soil adsorption sites; the effect of ca-
tion species and concentration with respect to soil
tightness and adsorption; the effects of high pH on soil
filterability and reduced adsorption capability; and
lastly, the reduced treatment capabilities of soil for
pathogens after shock loading of a toxic effluent (from
spills).
These possibilities suggest some reasonable, poten-
tial public health .implications. Human contact with
organisms on soil surfaces may result if winds,
machinery, or other human activity such as walking
reaerosolize the organisms and make them accessible
for inhalation. Runoff, either during intense effluent
application or precipitation, may cause significant
numbers of concentrated pathogens to enter surface
waters. Obviously this problem can be minimized by
proper design of the application site.
28
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Pathogenic Aerosols
In evaluating the potential problems associated
with pathogenic aerosols consideration must be given
to wastewater pathogen concentration and treatment
effectiveness, amount of wastewater aerosolization,
receptor distance from the sample and the prevailing
meteorological conditions.
Aerosols are defined as particles in the size range of
.01 to 50 or so micrometers (/ttm) which are suspended
in air. Direct means of human infection by biological
aerosols is by inhalation. The infectivity of a biological
aerosol is further dependent on the depth of
respiratory penetration. Biological aerosols in the 2-5
/jim size range are primarily captured in the upper
respiratory tract. These particles are removed by the
bronchial cilia and may ultimately pass into the
digestive tract. If gastro-intestinal pathogens are pre-
sent in the aeosols, a certain degree of infection may
result. However, a much higher incidence of infection
will result when respiratory pathogens are inhaled
into the alveoli of the lung. The greatest alveolar
deposition occurs in the 1-2 /j,m range and then
decreases to a minimum at approximately 0.25 /urn.
Below 0.25 fim, deposition again increases due to
Brownian movement in the lungs. It is imperative,
therefore, to have knowledge of the size and distribu-
tion of aerosols generated by spray irrigation equip-
ment under various meteorological conditions.
Specific studies of biological aerosols emitted by
spray irrigation of wastewater have not been found in
the literature. Some investigations have been con-
ducted on biological aerosols from trickling filters and
activated sludge systems. In general, it was found that
bacterial aerosols remain viable and travel further
with increased wind velocity, increased relative
humidity, lower temperatures and darkness.
For a given set of meteorological conditions, the
amount of wastewater aerosolized during spray irriga-
tion is a function of the spray equipment and
operating conditions employed. There are many
design choices of spray equipment such as the solid
set, rain gun and center pivot configurations.
Research is under way to determine the amount of
wastewater aerosolized and the particle size distribu-
tion for each of these spray configurations under
various meteorological conditions. These studies have
provided several preliminary conclusions worthy of
mention:
(1) Aerosols generated and leaving the immediate
vicinity of various spray irrigation rigs represents only
a fraction of one percent of the total applied test water.
(2) The average particle diameters of the droplets
making up the aerosol are in the 1-2 /*m size range.
Evaporation or dessication will significantly reduce
the aerosol's particle size, with the eventual size being
a function of the total solids content of the wastewater.
Suffice it to say that we are dealing with particles that
are small enough both to remain suspended in the at-
mosphere for considerable time and to penetrate and
be deposited in the lower respiratory tract.
(3) Although wind has always been considered im-
portant in controlling aerosol transport, this study has
shown that wind is very significant in aerosol genera-
tion. Greater aerosol is produced when sprays are into
the wind, than when sprays are at right angles to or
away from the wind. With most sprinklers involving
360 degrees rotation, and winds subject to frequent
changes in direction, control of aerosol production by
orientation of the spray with wind direction seems an
unreasonable approach to reducing potential health
hazards.
This study characterizes total aerosol output by
irrigation machinery and does not provide much in-
sight as to aerosolized pathogens. Their concentra-
tion, being some percentage of the total aerosol, may
be influenced by a variety of meteorological con-
ditions, such as relative humidity, wind velocity,
stability, sunlight and temperature.
Sunlight, through ultraviolet radiation, can be
deleterious to microorganisms including viruses. Its
effectiveness is significantly reduced at night and un-
der overcast conditions. Increased temperature can
reduce the viability of viruses, but mainly to the extent
of accentuating the effects of relative humidity
(Watkins, et ai, 1965)8. The more pronounced effects
do not appear until temperatures exceed 80°F, an un-
likely consistent condition in most parts of the United
States. The effects of temperature and sunlight,
therefore, can not be relied upon to provide significant
reductions in aerosolized pathogens for most con-
ditions.
Stability conditions and wind velocity are closely
related. As indicated earlier, the role of wind velocity
is important as it relates to the spray equipment
chosen, and consequently, the amount of aerosol
generated. Herein lies a major conflict. Although high
wind velocities result in larger amounts of aerosols
generated at the nozzle, stable atmospheric con-
ditions, characterized by low wind velocities and
darkness, result in higher concentrations of aerosol at
a downwind centerline position. It may well be that to
design for optimum wind velocity and stability con-
ditions may limit operating time and, therefore, be un-
desirable.
In general, relative humidity appears to have the
most pronounced effect on the viability of aerosolized
viruses and bacteria. Many enteric viruses exhibit a
similar trend: low survival at low relative humidities
and high survival at high relative humidities. General-
ly, bacteria and some bacteriophage show high sur-
vival at both low and high relative humidities, with
low survival at middle relative humidities.
The apparent advantages of low relative humidities
for viruses may be negated for two reasons. Dejong, et
al. (1974)9 in developing relative humidity data for
EMC viruses showed the infectious RNA was essen-
29
-------
tially unaffected over the entire relative humidity
range despite a more classical response for test system
infectivity of the virus. A second factor is illustrated by
the data in Table 3. For the northeastern site, the
relative humidity is 60 percent or higher 63 percent of
the time and 80 percent or higher 35 percent of the
time. In either case, depending on relative humidity to
provide substantial virus die-off would seem to be in-
advisable.
Table 3. FREQUENCY OF OCCURRENCE FOR
RELATIVE HUMIDITY
that filtration followed by disinfection with adequate
mixing will provide approximately a 3-log reduction in
the virus concentration. For operation conditions,
such as those planned for Muskegon, Table 4 presents
a comparison of costs for these two alternate situations
at various normal design flows.
Table 4. COMPARISON OF COSTS FOR 800
METER BUFFER ZONE AND FILTRATION AT
VARIOUS DESIGN FLOWS
(After Sorber, el al, 1974)5
Nominal Design Flow (mgd)
Relative Humidity
(Percent)
Time Greater Than (Percent)
Northeastern Site Southwestern Site
10
20
40
20
40
60
80
>99
89
63
35
80
44
21
7
It is reasonable to postulate that, if disinfection of
sewage is not complete and if pathogenic organisms
are aerosolized, evern very low numbers of these
organisms may be a potential public health hazard. In
an effort to evaluate this situation, we have developed
models describing the potential human risk for a varie-
ty of wastewater pathogen conditions, meteorological
conditions, and treatment schemes (Sorber, el al.,
1974)5. Unfortunately, field validation of these predic-
tions is not yet available. In all, this is a large area
which needs complete exploration.
It is interesting to relate the potential aerosol
problem to spray area design criteria. Predictions
through modeling indicate a 2-log reduction in virus
concentration can be achieved with an 800 meter
buffer zone. For comparative purposes, it is assumed
FAUNAE
Considerable interest has developed on the effect of
land application of wastewaters on changes in both
the populations and the disease incidence among wild
animals, birds, and mosquitoes. This interest should
be extended to cattle and other animals which may be
bred on the land application site as part of the overall
resource management program.
In a three-year study by Parizek, el al. (1967)10 at
Penn State, it was concluded that there were no
measurable changes in the populations of small
animals and birds in areas subjected to spray irriga-
tion. These workers, however, felt that the data served
Spray Area (acres)
Buffer Zone (acres)*
Capitol Cost of Buffer
Zone Land
© $500/acre
© $2000/acre
Filtration Costs \
Capitol Cost
(Mar 74) 5
Operating Cost
W/1000gal) a
700 1400 2800 5600
1400 1900 2800 3800
$ 700K $ 950K SHOOK S1900K
S2800K S3800K S5600K S7600K
$ 485K $ 775K $1260K S1940K
5.1 3.9 3.2 2.4
* Buffer zone of 800 m should provide a 2 log reduction of virus
concentration under most meteorological conditions (assumes no
protection of virus by solids).
f Filtration followed by disinfection with adequate mixing should
provide approximately 3 log reduction in virus concentration.
5 Adjusted to 1974 by ENRCC y = 1.94
o Adjusted to 1974 by factor 1.5
RESPONSES
only as a basis for measuring future changes inasmuch
as the spray irrigation had not altered the vegetation
enough to induce differences in bird and mammal
populations.
The point is that there are still conspicuous voids in
the literature in this general area. Additional informa-
tion required includes: the fate possible spread and
control of protozoan parasites; the possible passive
spread of microorganisms by flying insects; and the
capacity of wildlife, including migratory birds, to
carry infection great distances from a primary focus.
CHEMICAL CONSIDERATIONS
The environmental and public health concerns of
recycling municipal wastewaters on land must include
organic and inorganic chemical movement in the soil.
This topic could be extremely broad if industrial
wastes were applied to the land either separately or
combined with municipal wastewaters. In this discus-
sion, however, large quantities of industrial wastes will
not be considered.
Dissolved Soils
Dissolved chemical substances normally found in
water generally increase in concentration when used
30
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by man. Water of five Ohio municipalities in one cycle
of water use (i.e., raw water source through secondary
waste treatment plant) experienced an average in-
crease in total dissolved solids (TDS) concentration of
approximately 300 mg/1 (Bunch and Ettinger,
1964)11. When treated by land application techniques,
water may experience even larger increases in TDS
level if passed through certain soil systems. An ex-
treme example of this problem was illustrated at the
Imperial California Irrigation District where inflow
irrigation water had a TDS concentration of 1242
mg/1 and the outflow contained 3844 mg/1 (Bishop
and Peterson, 1969)12. Consequently, when land
application of wastewater results in recharge of
groundwater sources, TDS concentrations could ex-
ceed the levels recommended in the USPHS Drinking
Water Standards (1962)13. More important than an
aesthetically objectionable TDS level, the associated
high sodium content may be harmful to individuals
suffering with cardiac, renal and circulatory diseases
(McKee and Wolf, 1963)14.
Heavy Metal and Trace Organic Compounds
Heavy metals or toxic organic compounds are two
groups of materials that require special consideration
for disposal of wastewaters. Heavy metals, including
chromium, copper, lead, manganese and zinc, have in-
creased in concentration in soil where digested sludge
was being applied (Hinesly and Sosewitz, 1969)15.
With regard to trace organics, it is recognized that
essentially no information is available as to the specific
chemical makeup of municipal secondary wastewater
effluents. Consequently, it is difficult to assess the
effect of these compounds and their relationship to the
environmental and public health aspects of land
application of wastewaters.
The movement of dissolved chemicals with per-
colating water is primarily dependent on the nature of
the filtering soil. There have been instances of
groundwater contamination of soluble industrial
wastes. In one case in Germany, picric acid traveled
several miles and caused abandonment of a
groundwater supply (Lang and Burns, 1940)16.
Chemical elements are primarily removed in the soil
matrix by the process of ion exchange. Therefore, the
chemical clarification ability of soil is proportional to
its ion exchange capacity and clay soils, because of
their large surface area, have the largest exchange
capacities. Cationic exchange, one possible
mechanism for the removal of heavy metal ions and
ionized organic compounds, occurs until the exchange
capacity of the soil is exceeded. Also, they may be
released through exchange by other cations.
Pesticides
Pesticides persist in soil and water systems for vary-
ing periods, the length of persistence depending on
such factors as the chemical nature of the pesticide
itself, and the chemical, physical, and biological fac-
tors which promote degradation, translocation, or
metabolism. Due to the persistence of some pesticides
in soil and water systems, consideration must be given
to possible build-up of these compounds in the soil at
wastewater application sites.
Nitrogen Compounds
Biologically treated domestic wastewater contains
5-30 mg/1 of total nitrogen. The primary source of
this nitrogen is the nitrogen metabolism of man. The
dominant nitrogen form depends on the specific type
of treatment process, but it is usually in the form of
ammonia or nitrate. If ammonium ion is the dominant
nitrogen form, it will be adsorbed by the soil and,
eventually, be used in plant growth or biologically ox-
idized to nitrate. Therefore, if nitrate is not applied in-
itially, it may be formed biologically on or near the soil
surface. Nitrate ions are not adsorbed readily by most
soils and, if not utilized immediately by plants, they
end up in the groundwater.
Nitrate ion is the causative agent of
methemoglobinemia in children. Ingested nitrate is
biologically reduced to nitrite in the digestive tract.
Nitrite is then absorbed into the blood stream, ul-
timately causing suffocation by diminishing the ability
of the blood to carry oxygen. The USPHS Drinking
Water Standards (1962)13 recommended a concentration
of no more than 10 mg/1 for nitrate-nitrogen;
however, this value has been exceeded in a number of
groundwater supplies (Ward, 1970)17.
Nitrate-nitrogen levels above 10 mg/1 may develop
in areas where land application of wastewaters is used
for groundwater recharge, and where the recharged
groundwater is cycled back through the water supply
system.
As pointed out by Lance (1972)18, the removal of
nitrate-nitrogen by denitrification, specifically in a
groundwater recharge system, has not been clearly
demonstrated and is far from being proven. At pre-
sent, more research is needed to determine if both
nitrification and denitrification can proceed in a soil
which is used for land disposal of wastewaters.
CONCLUSIONS
Although this discussion has dealt with a large
number of environmental and public health concerns
relating to recycling of municipal wastewaters on
land, it should be emphasized that some ol these
problems can be minimized or eliminated by proper
site selection, system design and wastewater pre-
treatment including complete disinfection. To ac-
complish this end, each of these factors must be con-
sidered in light of the ultimate dispostion of the
wastewater. Specific conclusions we have developed
from this knowledge, or lack thereof, include:
(1) Many of the potential health and environmen-
31
-------
tal problems can be minimized by proper wastewater
treatment.
(2) Site selection is very important.
(3) Pathogenic aerosols near a spray site may be a
problem.
(4) Survival of many pathogens in wastewater
aerosols and soils is greater than indicator organisms.
(5) Ponding at the land application site will
enhance mosquito breeding.
(6) Na , NO3~ and total dissolved solids can
be a problem where wastewater recycle is
practiced.
Tables 5 through 7 identify research requirements
necessary to provide answers to many of the public
health and environmental questions related to recycl-
Table 5. PUBLIC HEALTH AND
ENVIRONMENTAL RESEARCH NEEDS
RELATED TO HUMAN PATHOGENS
The development of sensitive, quantitative pathogen detection
techniques (emphasizing viruses) for water, wastewater, soils
and spray irrigation aerosols.
The evaluation of the survival, distribution and hazard of aero-
solized pathogenic microorganisms disbursed by spray irriga-
tion equipment.
The conduct of a comprehensive epidemiological investigation
at a relatively large, operating wastewater land application site.
The comprehensive investigation of pathogen survival and trans-
port in soils, with particular emphasis on viruses.
The investigation of pathogen survival on crops and other
vegetation.
ing municipal wastewaters on land. Some of these
studies are already underway. Unfortunately, the
current level of effort will provide only minor insight
into the total knowledge required.
Table 6. PUBLIC HEALTH AND
ENVIRONMENTAL RESEARCH NEEDS
RELATED TO WILDLIFE AND CATTLE
The evaluation of long range effects of land application of waste-
water on plant, animal and disease vector ecology.
The evaluation of the capacity of wildlife, including migratory
birds, to carry infection or infectious agents great distances
from the land application site.
The evaluation of the effects of human and animal pathogens
and organic and inorganic wastewater components on domestic
food animals raised on feed crops at wastewater land appli-
cation sites.
Table 7. PUBLIC HEALTH AND
ENVIRONMENTAL RESEARCH NEEDS
RELATED TO CHEMICAL COMPONENTS
OF WASTEWATER
The evaluation of the persistence and translocation of heavy
metals in soils at wastewater land application sites.
The characterization and evaluation of the persistence and trans-
location of pesticides and trace organic constituents of waste-
water (and their metabolites) for their potential environmental
impact.
The comprehensive investigation of possible mechanisms for the
removal and/or conversion of problem inorganic species, espe-
cially nitrogen, which may tend to accumulate in groundwaters.
1. Sorber, Charles A., "Protection of the Public
Health", Proceedings of the Conference on Land
Disposal of Municipal Effluents and Sludges,
EPA-902/9-73-001, US Environmental Protec-
tion Agency, Region II, New York, 1973.
2. Sorber, C. A., S. A. Schaub and K. J. Guter,
"Problem Definition Study: Evaluation of Health 6.
and Hygiene Aspects of Land Disposal of
Wastewater at Military Installations",
USAMEERU Report No. 73-02, AD No.
752122, US Army Medical Environmental y
Engineering Research Unit, Edgewood Arsenal,
MD, 1972.
3. Buras, Netty, "Recovery of Viruses from
Wastewater and Effluent by the Direct Inocula- g
tion Method", Water Research, 8, 1 (January 1974).
4. Berg, Gerald, "Reassessment of the Virus
Problem in Sewage and in Surface and Renovated
Waters", in Progress in Water Technology, Vol. 3,
Oxford-New York: Pergamon Press Limited,
1973.
LITERATURE CITED
5. Sorber, C. A., S. A. Schaub and H. T. Bausum,
"An Assessment of a Potential Virus Hazard
Associated with Spray Irrigation of Domestic
Wastewaters", in Virus Survival in Water and
Wastewater Systems, Austin: Center for Research in
Water Resources (In Press).
Schaub, S. A. and Sorber, "Virus and Solids in
Water", Presented at the International
Conference on Viruses in Water, Mexico City
(June 1974).
. Kruse1, C. W., K. Kawata, V. P. Olivieri and K. E.
Longley, "Improvement in Terminal Disinfection
of Sewage Effluents", Water and Sewage Works, 120,
5 (June 1973).
. Watkins, H. M. S., L. J. Goldberg, E. F. Deig and
W. R. Leif, "Behavior of Colorado Tick Fever,
Vesicular Stomatitis, Neurovaccinia and
Encephalomyocarditis Viruses in the Airborne
State", Proceedings First International Symposium on
Aerobiology, Naval Biological Laboratories, US
Navy Supply Center, Oakland, 1965.
32
-------
9. dejong, J. C., M. Harmisen, T. Trouwborst and
K. C. Winkler, '' Inact ivat ion of
Encephalomyocarditis Virus in Aerosols: Fate of
Virus Protein and Ribonucleic Acid", Pallied
Microbiology, 27, \ (January 1974).
10. Parizek, R. R., L. T. Kardos, W. E. Sopper, E. A.
Myers, D. E. Davis, M. A. Farrell and J. B.
Nesbitt, "Wastewater Renovation and Conser-
vation", The Pennsylvania State University
Studies No. 23, The Pennsylvania State Universi-
ty, University Park, PA, 1967.
11. Bunch, R. and M. Ettinger, "Water Quality
Depreciation by Municipal Use", Journal Water
Pollution Control Federation, 36, 1411 (November
1964).
12. Bishop, A. and H. Peterson, "Characteristics and
Pollution of Irrigation Return Flow", US Depart-
ment of the Interior, Federal Water Pollution
Control Administration, Robert S. Kerr Water
Research Center, Ada, Oklahoma, 1969.
13. United States Public Health Service Drinking Water
Standards, US Department of Health, Education
and Welfare, Washington, DC, 1962.
14. McKee, J., and H. Wolf, Water Quality Criteria,
Second Edition, Publication No. 3—A, The
Resources Agency of California, State Water
Quality Control Board, 1963.
15. Hinesly, T. and G. Sosewitz, "Digested Sludge
Disposal on Crop Land", Journal Water Pollution
Control Federation, 41, 322 (May 1969).
16. Lang, A. and H. Burns, "On the Pollution of
Ground Water by Chemicals", Gas u. Water, 83, 6
Jan 40, from Journal American Water Works Associa-
tion Abstracts, 33, 2075 (November 1941).
17. Ward, P. C., "Existing Levels of Nitrates in
Waters - The California Situation", Nitrate and
Water Supply: Source and Control, Proceedings of
the 12th Sanitary Engineering Conference,
University of Illinois, 1970.
18. Lance, J. C., "Nitrogen Removal by Soil
Mechanisms", Journal Water Pollution Control
Federation, 7, 1352 (July 1972).
33
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-------
Educational and Informational Needs for Achieving Public Acceptance
by
John 0. Dunbar
Associate Director
Cooperation Extension Service
Purdue University
The basic problem we are concerned with in this
discussion is how to get people to think, feel, and act
more favorably toward recycling urban effluents and
sludges to the land.
For an idea such as recycling urban sewage and
sludge to the land to be implemented in our society, it
must have public acceptance. It must be acceptable to
the majority of the people. It must be actively sup-
ported by a large enough number of individual leaders
so that they can inform their constituents and keep
those who oppose it to a minimum. It must have
enough support by both private groups and public
agencies so that they will use their organizational,
financial, and political strength to bring about its im-
plementation.
We all know that people with vested interests may
be very hard to sell on this idea. They may not only be
hard to sell but able to block its implementation
almost indefinitely, especially if the public feels that
they are being treated unfairly or unjustly. Take for
example the farmer who may have heard that someone
is planning to spread city sludge on his farm. He is not
only aware but hostile, fearful, and concerned about
what will happen to his land and his family. If this
farmer's interests aren't considered and he isn't in-
volved in the planning or if he's treated arrogantly and
unfairly, the public and legislators who represent him
may decide that equitable and just treatment for him
is more important than clean water in a river. Public
opinion usually favors an underdog. Also, he may
know now only his commissioner and councilman and
his senator, and the governor. A surprisingly few such
people can block a seemingly good idea for a long
time. For these people the survival motive is very
strong and they'll give a great deal to protect their in-
terests.
I believe we can agree that the level of public sup-
port for this idea at this time is a great deal less than is
needed; therefore, we need to devise ways to generate
more support—i.e. to develop effective programs to
bring it about.
If this idea is to be accepted, we must secure for it a
higher place in the mind and active effort of many peo-
ple. Large numbers of people must become aware and
concerned. They must be informed about why it is be-
ing considered over other alternatives for disposing of
sludge; how it will work; its consequences in terms of
such things as dollar costs, effect on health, and on
agricultural production and on environment.
People must feel positive and not negative. They
must feel supportive of the idea, that it is progressive
and not regressive, that it will result in a net gain in
environmental quality, and that it is worth the extra
costs entailed. Feelings of uncertainty and suspicion
must be replaced by reliable factual information and
analysis. Feelings of frustration and hostility must be
replaced by feelings of mutual trust and dedication to
the common goal.
People must be willing to act in favor of this idea.
For this idea to be adopted, decisions must be made
and actions taken to support it. Clear thinking and
warm, positive feelings are not enough. Those already
in favor of the idea must be willing to work out com-
promises and publicly supported technical and finan-
cial assistance and retribution for those whose proper-
ty rights are damaged, all of which may be necessary
to win acceptance. Local, state, and federal agencies
must cooperate to get the largest public good for the
least social and economic cost. Elected representatives
of the people must provide legislation which both exer-
cises the will of the majority and protects the rights of
the minority. And local leaders and leaders of various
interest groups must be brought together to find ways
to either make this idea work or find a better alter-
native.
How do we bring about these changes in behavior?
For this analysis, I shall draw upon the works of Dr.
Gordon Lippitt, an outstanding psychologist, and Dr.
Ralph Tyler, nationally recognized educational
theorist and behavioral scientist plus my own ex-
perience and study of public policy education.
Why People Resist Change
First, let's look at Gordon Lippitt's analysis of why
people resist change. In brief, he says that people
resist change for the following reasons:
. . . When the purpose is not made clear—mystery
and ambiguity cause suspicion and anxiety. If
people can't tell where you're going, they may be
reluctant to join you for the trip.
. . . When they are not involved in the planning.
. . . When an appeal is based on your personal
reasons not theirs.
35
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. . . When their values, norms, and habits are ignored.
. . . When they don't understand something.
. . . When there is fear of failure, i.e., that the idea
won't work.
. . . When the costs (social and economic) are too
high in relation to the benefits or when they
believe the other alternative would be better.
. . . When the present situation seems satisfactory.
Why upset the applecart?
. . . When they think they may have to pay the costs
for benefits someone else will receive.
Overcoming Resistance to Change
Turning this coin over and looking at it from the
positive view, we have learned a great deal about how
to reduce resistance to change (i.e., increasing the
number of people for and reducing the number against
recycling urban sludge to the land). Some of the prin-
ciples are as follows:
. . . First recognize that some people are going to be
directly affected. Find out their interests and con-
cerns, what they'll likely to object to—then con-
centrate on meeting as many of their objectives as
possible.
. . . Involve the people in the diagnostic and creative
processes of decision making—they tend to un-
derstand and support what they create. People
riding in the boat with you seldom drill a hole in
the bottom.
. . . Allow the people to blow off steam. Too often peo-
ple pushing an idea try to move ahead "so fast
that the opposition won't have a chance to
organize." These famous last words show lack of
appreciation for the principle of "catharsis"—to
relieve emotion so that objective discussion and
deliberation can take place. Don't fear it! En-
courage it!
... Be certain that people agree upon the goals and
reasons for the change. Clarify the whys and
wherefores.
. . . Build a trusting climate—
. . .Tell the truth.
. . .Maintain open communications.
. . .Don't spring decisions on them.
. . .Develop mutual respect.
. . . Provide the information needed for people to
think intelligently. This provides the basis for
people to make sound decisions.
. . . Keep people informed. They will get more in-
timately involved if they know the latest details on
environmental quality problems and what will
likely happen if we recycle urban sludge on to the
land.
Our own experiences in dealing with our friends,
our families, the people with whom we work, and the
public lead us to these conclusions.
Helping People Acquire New Behaviors
We who wish people to change their behavior
seldom can get them to do so by saying "You ought to
think, feel, or act differently". Neither can we coerce
them into it. What we can do is provide stimuli which
hook their interests or concerns—clean water to drink,
better fishing, more swimming areas. Then, they will
behave differently—we hope more positively—toward
recycling urban sludge to the land, we will have
achieved our goal.
Now let's turn to Dr. Tyler. He adds the following
to Dr. Lippitt's suggestions on how to get people to
change their behavior.
. . . For a change of behavior to take place, the person
must perceive a connection between what he is
learning and how it affects his own life, e.g.,
provides a safer environment, so he's for it; or,
spreads heavy metals on his land so he's against
it.
. . . Change is more rapid when people get informa-
tion from a variety of approaches in which they
can see common elements in a variety of
situations.
. . . Each idea and relationship must be within the
person's ability to perceive at his level of interest,
concern, and knowledge.
... In designing information programs, clarify the
behavior you seek to develop in the individuals.
With reference to recycling sludge to the land,
what behavior do we wish to stimulate? Examples
are:
. . . Do the people lack interest? If so, the
behavior we need to develop is "greater in-
terest."
... Do the people need to develop an attitude of
concern for public welfare? If so, we need to
help them see the effects of pollution on our
rivers and lakes.
. . . Are they familiar with the various methods of
dealing with the problem (urban sludge in
this instance)? If not, our goal should be to
acquaint them with what the choices are.
... Do they need greater ability to predict
probable consequences of alternative
methods of disposal or sludge? If yes, we need
to provide them with the information on what
would happen if we were to implement
various alternatives (how they work, costs in-
volved, benefits, who pays the costs, who
benefits).
A PROPOSED EDUCATIONAL AND IN-
FORMATIONAL PROGRAM
On the basis of the problem we face in winning
public support for recycling urban sludge to the land
and the principles of behavioral change outlined
above, let me propose an Educational and Infor-
36
-------
mational Program. In developing such programs, we
face five fundamental questions:
\. Whom specifically are we beaming the program toward?
Who are the target audiences? Different segments of
society have different interest levels, differences in
prior knowledge and understanding, different vested
interests, and different concerns. So far greatest
effect, we approach each of them in a different way.
For this program, I identify four major audiences:
(1) The uninterested general public.
(2) Decision makers and others already concerned
about the environment and different ways of
handling urban sludge.
(3) People with vested interests.
(4) Professionals from government agencies and in-
stitutions who work directly with the people
who will be most affected by this decision.
2. What behavioral changes do we wish to bring
about in each segment?
. . .Awareness and interest.
. . .A decision to believe in an idea.
. . .Active engagement in support of the idea.
. . .Involvement in modification and innovation to
put the idea into effect.
Differentiation in interest and knowledge among
various target audiences make it necessary to con-
centrate on behavior changes appropriate to each.
Also, mass methods and media are most effective
and economical for some behavioral changes, while
face-to-face contact is best for other.
3. What information is needed to capture the attention and in-
terest of the people in each audience and to bring about the
desired behavioral change?
It takes different information to interest the public-
spirited citizen not directly involved than it does to
interest an irate farmer who has his mind made up
that "they're not going to dump that city sludge on
my land."
Also, it is important to figure out exactly which information
is needed by the audience concerned so as not to bore people
with something they already know or waste time and money
trying to "teach them more than they want to need to know
to change their behavior."
4. What is the best combination of educational
methods for bringing about the type of change
desired?
Now, from this let us put together a four part
educational program, one for each target audience.
Part I. For the general public:
a. Behavioral changes we seek—greater awareness, in-
terest, and concern about recycling urban sludge to
the land.
b. Methods—clarify goals. Attach a new interest
(recycling sludge to the land) to an old one (reduc-
ing pollution of the water). The public knows that
people in cities and towns are going to continue to
produce sewage and that it must be disposed of
some way. They also know that it is impossible to
use septic tanks and disposal fields for large con-
centrations of people. They know that sewage goes
into sewers. Beyond that, they don't know
much—nor do they care, unless sewage disposal
becomes a problem—which it has.
c. Means of communication—news releases and feature
stories in mass media (TV, radio, newspapers,
magazines) and speeches.
Part 2. For decision makers and other concerned about the en-
vironment and different ways of handling urban
sludge:
This includes lay leaders, legislators, elected of-
ficials, interest groups, and leaders of various in-
stitutions serving the public.
a. Behavioral changes we seek—active support for recycl-
ing sludge to the land.
b. Methods—broaden the peoples base of knowledge
and understanding about ways of handling sludge
and the consequences of each. With this knowledge
people can make choices based upon their own
value system, which hopefully already includes a
desire for cleaning up the environment.
First, they must be given comparative knowledge
about all the alternatives. Among the alternatives
are:
. . . Recycling sludge to good farm land.
. . . Recycling sludge to the lakes, rivers, or ocean.
. . . Putting it on strip mined land.
. . . Other
For each alternative, we should also provide an
analysis of such things as
. . . Dollar costs in terms of aggregates for a city, or
per capita, or some other meaningful figure.
. . . Where the money comes from to pay the costs.
. . . Effect on the environment to which the sludge is
being recycled. Include the physical, biological,
human, and economic effects.
. . . Effect on human health.
. . . Other.
The simplest way to get people to look favorably
upon one alternative is to let them compare it with
others so that they can tell which one they favor.
This takes some courage on the part of
professionals and planners—and some faith in the
judgment of the public. But if we don't have that,
we haven't much faith in democracy.
We in Public Policy Education call this the
Problems—Alternative—Consequences approach.
c. Means of communication—being somewhat difficult to
present, emphasis should be given to face-to-face
contact where possible in lectures, symposia,
forums, and seminars. People need opportunities to
discuss this with experts. Carefully prepared
pamphlets, leaflets, and feature stories are excellent
supplements.
Part 3. For people with vested interests which will have to be
dealt with before the idea can be accepted.
This includes legislators who must prepare legisla-
tion, public officials whose duty it is to make decisions,
37
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and citizens who will be significantly affected.
a. Behavior changes we seek—favorable action, reduced
criticism.
b. Methods—include them in the formulation of
decisions, working out compromises, finding better
alternatives, and compensating those hurt by the
decision. Even though most of this group of people
has a vested interest to protect, they also know
enough to realize that sludge must be disposed of
some way and that ways must be found to keep the
environment clean.
It should be recognized that many of these peo-
ple have a positive attitude, excellent minds, and
great knowledge with which to supplement the
brainpower of the professionals. They are in some
ways a free resource.
And there are some don'ts: (1) Don't try to sell
smart people a bill of goods (2) Don't ask leaders to
be a rubber stamp.
Part 4 For the professionals from federal, state, and local
government agencies and institutions who work closely
and directly with the people affected by the decision:
a. Behavioral changes we seek—greater knowledge,
favorable attitudes, active support.
b. Methods—involvement. They know a great deal
about the people on whom the decision will im-
pinge and have a great deal of information at their
fingertips to contribute to the educational
processes necessary to win public support. And
they have a desire to help.
c. Means of communication—-personal contact, seminars
in which all "agencies" are included.
In conclusion, a great deal can be accomplished
with an educational and informational program to win
public acceptance of recycling urban sewage and
sludge to the land. In order to use our limited
resources efficiently, such programs should be careful-
ly thought through and planned carefully so that the
necessary information can be developed and dis-
seminated as quickly as possible.
We should remember that the changing of public
opinion takes time. For people to acquire information
and change their ways of thinking, feeling, and action
is a slow process. To settle issues such as this may take
2 to 10 years.
Remember—Leadership consists of getting people to do
what you want them to do because they want to do it!
Lippitt Gordon L., "Overcoming Human Resistance
to Change," Selected Perspectives for Community Re-
source Development (North Carolina State University,
Raleigh, North Carolina).
Public Affairs Education, A report of the Cooperative
Extension Service Committee on Policy (Extension
Service, U. S. Department of Agriculture, Wash-
ington, D. C., 1969).
Tyler, Ralph W., "How Do People Learn," Increasing
Understanding of Public Problems and Policies (Farm
Foundation, Chicago, Illinois, 1953).
38
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Experiences at Penn State with Land Application
by
William E. Sopper
School of Forest Resources
The Pennsylvania State University
University Park, Pennsylvania
The Waste Water Renovation and Conservation
Project was designed in 1962 and was put into opera-
tion in 1963. It was one of the first comprehensive
research projects in the United States to investigate
the feasibility of disposing of large volumes of secon-
dary treated sewage effluent on the land by spray
irrigation. From these investigations the "Living
Filter" concept was evolved. The term was first used
for the title of a black and white film produced in 1965
depicting some of the early results of the project. Since
then, the term "Living Filter" has become more or less
synonymous with the idea of spray irrigation of
municipal wastewater on the land.
The idea embodied in this concept is to apply
wastewater on the land in such a manner so as to
utilize the entire bio system—soil, vegetation,
microorganisms—as a living filter to renovate the
wastewater for direct recharge to the groundwater
reservoir. This can be accomplished by controlling
application rates and by maintaining normal aerobic
conditions within the soil. Under these conditions
organic and inorganic contituents in the wastewater
are removed and degraded by microorganisms,
chemical, precipitation, ion exchange, biological
transformation, and biological absorption through the
root systems of the vegetative cover. The utilization of
the vegetative cover as an integral part of the system to
complement the microbiological and physiochemical
systems in the soil is an essential component of the liv-
ing filter concept and provides for maximum renova-
tion capacity and durability of the system.
Treated municipal sewage effluent has been spray
irrigated on cropland and in forested areas for a 12-
year (1963-1974) period at the Penn State Project.
The results of this research will be used to illustrate
some of the benefits and evils of a land application
system. Forested areas irrigated consisted of a mixed
hardwood forest, a red pine plantation (Pinus resinosa),
and a sparse white spruce (Picea slaucd) plantation es-
tablished on an abandoned old field. Types of crops
irrigated were wheat, oats, corn, alfalfa, red clover,
and reed canarygrass. Detailed descriptions of these
areas have been previously reported by Parizek et. al.
(1967) and Sopper (1968, 1971). The two soil types
present on the site are the Hublersburg with a surface
texture ranging from silt loam to silty clay loam on
slopes ranging from 3 to 12 percent and the Morrison
sandy loam with slopes ranging from 3 to 20 percent.
Sewage effluent was applied in various amounts
ranging from 2.5 cm per week to 15 cm per week and
over various lengths of time ranging from 16 weeks
during the growing season to the entire 52 weeks.
Rates of application varied from 6.2 to 16 mm per
hour.
CHEMICAL COMPOSITION OF MUNICIPAL
SEWAGE EFFLUENT
The chemical composition of municipal effluent is
illustrated in Table 1 based upon samples collected
from the University treatment plant. Treatment con-
sists of both primary and secondary treatment. Secon-
dary treatment includes standard and high-rate trick-
ling filters and a modified activated sludge process
followed by final settling. The total amount of each
constituent applied per acre year at the 5 cm per week
application rate is also given in Table 1.
The fertilizer value of these wastewaters is readily
evident in that the 5 cm per week application provides
commercial fertilizer constituents equivalent to ap-
proximately 233 kilograms of nitrogen, 224 kilograms
of phosphate (P2O5), and 254 kilograms of potash
(K2O). This would be equal to applying about 2200
kilograms of a 10-10-11 fertilizer annually.
Table 1. TYPICAL CHEMICAL COMPOSITION
OF MUNICIPAL SEWAGE EFFLUENT
Constituent
Average
Concentration
Total Amount
Applied1
mg/1
kg/ha
PH
MBAS
Nitrate-N
Organic-N
NH4-N
P
Ca
Cl
Mg
Na
Fe
8.1
0.37
8.6
2.4
0.9
2.651
25.2
41.3
12.9
28.1
0.4
6
143
40
14
44
420
792
215
469
9
ug/1
kg/ha
B
Mn
Cu
Zn
Cr
Pb
Cd
Co
Ni
169
61
109
211
23
104
9
62
93
3.26
1.15
1.96
4.15
0.41
2.12
0.19
1.24
1.82
'Total amount applied on areas which received 5 cm of effluent
per week.
39
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RENOVATION
Agronomic Areas
Nitrogen and phosphorus are the two key eutrophic
elements in municipal wastewater and therefore dis-
cussion on renovation will be limited to these two
elements. The overall efficiency of the biological
system to accept and renovate wastewater can be
evaluated by observations on the quality of percolating
water within the surface soil mantle. Suction
lysimeters installed in all areas were used to obtain
samples of percolating water at the 120 cm soil
depth. Percolate samples were collected, whenever
possible, after each weekly application of wastewater
and analyzed for the same constituents as the waste-
water.
Mean annual concentrations of phosphorous and
nitrate-nitrogen for the agronomic areas during the
period 1965 to 1973 are given in Tables 2 and 3. Mean
annual phosphorus concentrations in the sewage
effluent have varied from 2.5 to 10mg/l. Phosphorus
concentrations in the percolating water at the 120 cm
soil depth have been consistently decreased by more
than 98 percent since the initiation of the project in
1963. Even when application rates were increased
from 5 to 7.5 cm per week in 1972-73 the degree of
renovation was essentially unchanged. The differences
between the mean annual concentrations of
phosphorus on the control and irrigated areas are
quite small and insignificant considering that more
than 13 meters of sewage effluent have been applied
over the 11 years. It should also be noted that starting
in year 1971 the reed canarygrass areas has been
irrigated with a mixture of sewage effluent and liquid
digested sludge (approximately one part of sludge
slurry to eleven parts of effluent). This effluent-sludge
mixture had a total phosphorus concentrations of 20
Table 2. MEAN ANNUAL CONCENTRATION
OF PHOSPHOROUS IN SUCTION LYSIMETER
SAMPLES COLLECTED AT THE 120-CM SOIL
DEPTH IN THE CORN ROTATION PLOTS AND
THE REED CANARYGRASS AREA
Corn
Year
cm per week
0 5
Reed Canarygrass
cm per week
0 5
mg/1
mg/1
mg/1
mg/1
1965
1966
1967
1968
1969
1970
1971
1972*
1973*
0.032
0.045
0.039
0.041
0.066
0.034
0.048
0.022
0.013
0.022
0.036
0.054
0.060
0.070
0.075
0.061
0.035
0.020
—
—
—
—
—
—
—
0.067
0.036
—
0.055
0.053
0.052
0.035
0.038
0.061
0.054
0.052
Table 3. MEAN ANNUAL CONCENTRATION
OF NITRATE-NITROGEN IN SUCTION
LYSIMETERS SAMPLES COLLECTED AT THE
120-CM SOIL DEPTH IN THE CORN ROTA-
TION PLOTS AND THE REED CANARYGRASS
AREA
Corn
Year
cm per week
0 5
Reed Canarygrass
cm per week
0 5
mg/1
mg/1
mg/1
mg/1
1965
1966
1967
1968
1969
1970
1971
1972*
1973*
5.2
4.7
3.4
4.5
9.4
10.3
6.2
9.4
7.4
9.7
7.0
7.1
9.5
13.5
10.9
9.6
10.6
7.4
—
—
—
—
—
—
—
1.7
1.5
—
3.7
3.3
3.1
2.5
2.4
3.3
7.7
9.2
*Application rate increased to 7.5 cm per week.
*Application rate increased to 7.5 cm per week.
to 25 mg/1 and an orthophosphate level of 10 to 15
mg/1. These data indicate that phosphorus is not
leaching out of the soil profile into the groundwater at
significantly higher concentrations from the
wastewater treated areas than from the control areas
and that there appears to be no decreasing trend evr-
dent in terms of satisfactory phosphorus removal.
Nitrate-nitrogen renovation was not as efficient on
the agronomic areas. Nitrate-nitrogen concentrations
were decreased below the 10 mg/1 level recommended
by the Public Health Service for drinking water on the
corn rotation area which received the 2.5 cm per week.
treatment but not at the 5 cm per week level. At the
higher application rate (5 cm) the mean annual con-
centration remained below the PHS limit only when
grass-legume hays occupied 28 to 68 percent of the site
during the period 1965 to 1968. Starting with 1969 the
entire site has been planted with corn. Increases in the
application rate from 5 to 7.5 cm during 1972 and
1973 did not significantly affect the degree of renova-
tion on the corn area.
On the other hand, the 5 cm per week reed
canarygrass areas has been exceptionally efficient in
nitrogen removal and has consistently maintained the
mean annual concentration of nitrate-nitrogen in per-
colating water below the 10 mg/1 limit. This area is
irrigated year-around and therefore received twice as
much nitrogen as the corn area. Even when applica-
tion rates were increased to 7.5 cm per week during
1972 and 1973, mean annual concentrations were in-
creased somewhat but still remained within accep-
table levels.
40
-------
Forested Areas
The forested areas were highly efficient in removing
phosphorus (Table 4). Mean annual concentrations
are slightly higher than that of the agronomic areas
because there is no harvested crop and the phosphorus
is continually recylced. Year-around irrigation of the
forest areas on the Morrison soil at the 5 cm per week
level has resulted in a substantial increase in
phosphorus concentration in the soil percolate. As
shown in Table 4, there has been a steady increase in
comparison to the control area since the third year
(1968) of operation. On the other hand, phosphorus
concentrations in the irrigated forest areas on the
Hublersburg soil which received lower application
rates and shorter periods of irrigation (growing season
irrigation period did not appear to reduce renovation
efficiency.
The efficiency of forested areas to reduce nitrogen
concentrations have been variable. It appears that
forested areas can accept a 2.5 cm per week applica-
tion of wastewater without having the mean annual
concentration of nitrate-nitrogen exceed the PHS limit
(Table 5). However, year-around irrigation of forests
at 5 cm per week consistently resulted in no renova-
tion. It also appears that forest ecosystems may be
quite sensitive to wastewater application rates and
may have a low threshold in terms of collapse in the
renovation system. A 50 percent increase in the
Table 4. MEAN ANNUAL CONCENTRATION OF PHOSPHORUS IN SUCTION LYSIMETER
SAMPLES COLLECTED AT THE 120-CM SOIL DEPTH IN THE FORESTED AREAS.
Year
Red Pine
Hublersburg Soil
cm per week
0 2.5
Hardwood
Hublersburg Soil
cm per week
0 2.5
Old Field
Hublersburg Soil
cm per week
0 5
Hardwood
Morrison Soil
cm per week
0 5
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
1965
1966
1967
1968
1969
1970
1971
1972
1973
0.040
0.043
0.053
0.075
0.010
0.065
0.994
0.113
0.028
0.300
0.134
0.092
0.089
0.064
0.076
0.107
0.105'
0.035'
0.050
0.037
0.044
0.106
0.072
0.033
0.015
0.078
0.022
0.250
0.043
0.077
0.222
0.047
0.143
0.146
0.037'
0.051'
0.030
0.039
0.040
0.051
0.042
0.039
0.074
0.042
0.460
0.140
0.068
0.053
0.098
0.114
0.420
0.2002
0.0962
0.059
0.068
0.071
0.059
0.051
0.037
0.033
0.020
0.042
0.063
0.116
0.137
0.209
0.378
0.335
0.392
'Application rate increased to 3.8 cm per week.
Application rate increased to 7.5 cm per week.
Table 5. MEAN ANNUAL CONCENTRATION OF NITRATE-NITROGEN IN SUCTION LYSIMETER
SAMPLES COLLECTED AT THE 120-CM SOIL DEPTH IN THE FORESTED AREAS.
Year
Red Pine
Hublersburg Soil
cm per week
0 2.5
Hardwood
Hublersburg Soil
cm per week
0 2.5
Old Field
Hublersburg Soil
cm per week
0 5
Hardwood
Morrison Soil
cm per week
0 5
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
'Application rate increased to 3.8 cm per week.
Application rate increased to 7.5 cm per week.
mg/1
mg/1
1965
1966
1967
1968
1969
1970
1971
1972
1973
0.9
0.1
0.9
0.9
0.2
<1
2.6
6.0
0.5
2.2
2.1
1.7
2.7
4.2
5.3
8.3
21.8'
13.7'
—
0.1
0.3
0.1
0.1
<1
0.5
14.7
3.7
0.0
0.2
1.4
8.0
7.2
5.0
5.8
23.9'
13.5'
0.3
0.1
0.3
0.2
0.2
<1
0.5
3.2
0.5
8.0
5.0
6.1
3.7
2.3
3.5
3.8
11. 82
13. 52
_
0.1
1.4
0.1
0.3
1.0
0.8
4.7
1.3
10.6
19.2
25.9
23.7
42.8
17.6
22.9
17.3
41
-------
application rates (2.5 to 3.8 cm and 5 to 7.5 cm) after 9
years of successful operation and renovation resulted
in a complete break-through in terms of concen-
trations of nitrate-nitrogen in percolating water. Mean
annual concentrations nearly tripled the first year
(1972) and all exceeded 10 mg/1.
Table 6. MEAN ANNUAL CONCENTRATION
OF NITRATE-NITROGEN IN SUCTION
LYSIMETER SAMPLES COLLECTED AT THE
120-CM SOIL DEPTH IN THE RED PINE
PLANTATION IRRIGATED
AT 5 CM PER WEEK.
Red Pine
Hublersburg Soil
Year
cm per week
1965
1966
1967
1968
1969
1970
1971
1972
1973
0
mg/1
0.9
0.1
0.9
0.9
0.2
1
2.6
6.0
0.5
5
mg/1
3.9
9.3
13.8
19.9'
24.22
8.3
2.9
14. 53
9.03
'Blowdown in November, 1968.
2A11 pine trees cut and removed.
'Application rate increased to 7.5 cm per week.
The Old Field area has been somewhat exceptional
in comparison to the other forest areas in terms of
nitrogen renovation. This area receives the highest
application rate on the Hublersburg soil and yet has
consistently maintained nitrate-nitrogen levels below
10 mg/1 throughout the 9 year period (1963-1971)
without the harvest of any crop. In 1963 at the start of
the project the area was primarily an open weed field
with a few scattered spruce saplings (1 to 2 meters in
height). Although the trees are now more than 7
meters in height the spruce stand is still sparse with
fairly large open areas. It appears that the annual and
perennial weeds which occupy these open areas dur-
ing the growing season (irrigation period) provide a
temporary storage for nitrogen and hence reduce.
nitrate-nitrogen leaching losses. In the fall, vegetative
growth ceases and nitrates are again available for
leaching. However, since irrigation has ceased by this
time, the concentrations of nitrate-nitrogen in per-
colate water remains at a low level.
This same phenomena was observed in the red pine
plantation which was irrigated at the 5 cm per week
level. Mean annual concentrations of nitrate-nitrogen
steadily increased from 1963 to 1969 (Table 6). In
November, 1968 a snow storm resulted in complete
blow-down of the plantation. In 1969 the area was
clearcut and all trees were removed. Immediately a
dense cover of herbaceous vegetation developed which
was similar to that on the irrigated Old Field area. As
a result the mean annual concentration of nitrate-
nitrogen decreased from 24.2 mg/1 in 1969 to 8.3
mg/1 in 1970 and to 2.9 mg/1 in 1971. Subsequent in-
creases in 1972 and 1973 were due to the increased
application rate.
EFFECTS ON CHEMICAL PROPERTIES
OF THE SOIL
Soil samples were taken on all areas to a depth of
150 cm in the fall after cessation of irrigation in 1963,
1967, and 1971. Soil samples were analyzed for the
same constituents as was the effluent to determine if
any significant concentrations of nutrients were ac-
cumulating in the irrigated areas.
The exchangeable cations (K, Ca, Mg, Na, and
Mn) and boron were extracted from the soil with am-
monium acetate (Jackson, 1958) and analyzed with an
arc spectrometer (Baker, et. al., 1964). Exchangeable
hydrogen was determined using a barium chloride
buffering technique (Jackson, 1958). Organic matter
was determined using a potassium dichromate-
sulfuric acid oxidation method (Peech, et. al., 1947).
Soil pH was measured with a glass electrode using a
1:1 soil to water mixture. Total nitrogen was analyzed
using a modified Kjeldahl method to include nitrates
(Jackson, 1958). The phosphorus concentration was
determined by using the Bray extraction procedure
(Jackson, 1958).
The results of the soil analyses for 1963 and 1971 for
the two areas on each soil type which received the
highest applications of effluent are given in Tables 7
and 8. These two areas were the old field 5-cm area on
the Morrison soil.
Results of the soil analyses of the 1971 samples in-
dicated that the effects of effluent irrigation on ex-
changeable potassium, organic matter, pH, and total
nitrogen were small and inconsistent. However, there
were significant changes in the concentrations of
calcium, magnesium, sodium, manganese, boron, and
phosphorus. Calcium, magnesium, and boron concen-
trations increased significantly at the 30-cm depth in
both the Hublersburg and Morrison soils and in all
the vegetative cover types. Sodium concentrations in-
creased significantly at all depths in the Hublersburg
and Morrison soils and in all the vegetative cover
types. Manganese concentrations decreased
significantly in the upper 90 cm of the Hublersburg
soil on the hardwood 2.5 cm treated plot and the up-
per 90 cm of the Morrison soil on the new gameland
hardwood 5-cm treated plot. Phosphorus concen-
42
-------
Table 7. MEAN CONSTITUENT CONCENTRATIONS FOR THE OLD FIELD 5-CM AREA
ON THE HUBLERSBURG SOIL TYPE
Year
and
Area
1963
Control
1963
Treatment
1971
Control
1971
Treatment
TableS. MEAN
Year
and
Area
1967
Control
1967
Treatment
1971
Control
1971
Treatment
Depth
cm
30
60
90
120
150
30
60
90
120
150
30
60
90
120
150
30
60
90
120
150
K
0.40
0.47
0.47
0.43
0.47
0.63
0.60
0.63
0.53
0.47
0.10
0.03
0.00
0.03
0.00
0.43
0.20
0.06
0.16
0.13
Ca
1.43
2.00
1.13
0.93
0.97
1.73
1.87
1.03
0.77
0.57
2.00
2.16
1.80
1.53
1.16
3.33
2.00
1.40
1.00
1.00
ME/lOOgms
Mg Na
0.27 0.10
0.83 0.17
1.27 0.20
1.57 0.20
1.53 0.13
0.50 0.23
0.90 0.20
1.00 0.10
0.97 0.10
0.77 0.10
0.23 0.23
0.80 0.23
1.43 0.23
1.63 0.20
1.50 0.20
1.73 0.33
1.33 0.30
1.23 0.33
1.36 0.30
1.43 0.33
H
11.84
8.67
9.33
—
—
16.06
18.74
11.48
—
—
14.91
11.56
12.05
—
—
15.52
16.36
16.68
—
—
CONSTITUENT CONCENTRATIONS FOR
Depth
cm
30
60
90
120
150
30
60
90
120
150
30
60
90
120
150
30
60
90
120
150
K
0.16
0.16
0.16
0.26
0.06
0.13
0.06
0.13
0.16
0.26
0.00
0.16
0.26
0.20
0.00
0.06
0.03
0.10
0.03
0.13
Ca
0.90
0.70
0.46
0.43
0.36
1.36
0.50
0.46
0.60
1.46
0.53
1.13
0.76
0.53
0.50
1.86
0.96
1.30
1.10
0.73
MORRISON
ME/100gms
Mg Na
0.10 0.16
0.33 0.16
0.33 0.20
0.53 0.20
0.56 0.20
0.40 0.23
0.30 0.23
0.36 0.23
0.36 0.20
1.10 0.26
0.10 0.20
0.80 0.20
1.03 0.20
0.83 0.20
0.96 0.16
0.53 0.23
0.36 0.20
0.73 0.20
0.83 0.23
0.80 0.23
Mn
71.60
20.46
23.46
18.60
18.13
44.60
20.80
26.00
62.00
17.93
15.86
12.13
10.60
9.46
8.66
14.53
17.20
15.80
15.66
16.06
THE
PPM
B
0.53
0.60
0.53
0.53
0.53
1.00
0.80
0.86
0.80
0.80
0.06
0.06
0.00
0.06
0.00
0.60
0.20
0.06
0.06
0.13
P
8.70
0.76
0.38
0.38
0.38
16.05
1.48
0.71
0.00
0.00
10.95
0.91
1.00
0.90
1.78
50.80
3.48
1.90
1.66
1.76
HARDWOOD
PH
4.79
5.23
4.91
—
—
4.96
4.68
4.45
—
—
5.06
4.89
4.84
—
—
5.42
4.99
4.82
—
—
5-CM
%N
0.088
0.016
0.012
0.010
0.010
0.072
0.022
0.019
0.014
0.016
0.082
0.016
0.009
0.005
0.005
0.095
0.026
0.017
0.020
0.028
%OM
2.147
0.370
0.167
—
—
2.407
0.390
0.183
—
—
2.683
0.313
0.167
—
—
2.300
0.343
0.190
—
—
AREA ON THE
SOIL TYPE
H
13.43
12.07
10.38
—
—
12.94
10.76
13.37
—
—
13.72
13.36
11.54
—
—
7.35
5.20
9.34
—
—
Mn
55.93
16.46
10.46
4.80
10.13
19.93
11.86
19.20
16.26
15.33
32.73
11.00
10.86
9.86
7.26
4.13
4.93
5.73
6.40
4.20
PPM
B
0.26
0.13
0.13
0.33
0.06
0.26
0.00
0.13
0.13
0.20
0.06
0.20
0.26
0.20
0.00
0.13
0.20
0.13
0.06
0.20
P
16.50
2.13
1.23
0.83
0.88
75.55
4.90
2.18
1.92
1.50
6.25
3.16
0.66
1.06
0.68
143.75
31.60
9.95
1.98
0.98
PH
4.55
4.67
4.76
—
—
5.50
4.99
4.94
—
—
4.96
4.97
4.99
—
—
6.15
5.51
5.06
—
—
%N
—
—
—
—
—
—
—
—
—
—
0.109
0.036
0.028
0.023
0.016
0.084
0.052
0.037
0.032
0.032
%OM
2.210
0.547
0.223
—
—
1.240
0.560
0.350
_
—
2.867
0.300
0.230
—
—
1.483
0.413
0.243
—
—
43
-------
trations increased significantly in the Hublersburg soil
in the 30-cm depth of the hardwood 2.5 cm plot, the
upper 60 cm of the old fields 5-cm and red pine 2.5 cm
plots. Phosphorus also increased significantly in the
upper 150 cm of the Morrison soil on the new
gameland hardwood 5-cm plot.
Of the 11 constituents analyzed, only potassium,
sodium, manganese, exchangeable hydrogen, boron,
and phosphorus had significant changes over time.
Potassium concentrations decreased in all five depths
of the treated and control plots in the Hublersburg soil
on the old field 5-cm plots. Sodium concentrations in-
creased significantly in all five depths of the
Hublersburg soil in the old field 5-cm treated plot, the
60 and 90 cm depths of the hardwood 2.5-cm treated
plot, and the lower 90 cm of the red pine 2.5-cm
treated plots. Manganese concentrations decreased
significantly in all five depths on both soil types and in
all vegetation cover types. Exchangeable hydrogen
concentrations decreased significantly in the upper 90
cm of the Morrison soil on the new gameland
hardwood 5-cm treated plot. Boron decreased
significantly in all five depths of the Hublersburg soil
on the old field 5-cm and red pine 2.5-cm treated
plots. Phosphorus increased significantly in the 30 cm
of the Hublersburg soil on the hardwood 2.5-cm and
red pine 2.5-cm treated plots, and in the upper 90 cm
of the Hublersburg soil on the old field 5-cm and the
Morrison soil on the new gameland hardwood 5-cm
treated plots.
CROP RESPONSES
Yields
During the initial years of the project a variety of
crops were tested. Average annual crop yields during
the period 1963 to 1970 have previously been reported
by Sopper and Kardos (1973). Since 1968 the two
primary crops grown have been silage corn and reed
canarygrass. Our experience has shown that these two
crops are the best suited to our site and are the most
efficient in terms of nutrient utilization. During the
past 12 years the crop areas irrigated with 5 cm of
effluent weekly have received a total of approximately
20 meters of wastewater. During this period annual
yield increases have ranged from 0 to 350 percent for
corn grain, 5 to 130 percent for corn silage, 85 to 190
percent for red clover, and 79 to 140 percent for alfalfa.
Nutrient Composition
Under the "living filter" concept the vegetative
cover is an integral part of the system and should com-
plement the microbiological and physiochemical ac-
tivities occurring within the soil to renovate the
effluent by removal and utilization of the nutrients
applied. The crops harvested from the irrigated areas
are usually higher in nitrogen and phosphorus than
the control crops, however, the differences are not
large. This is partially due to the fact that the control
areas receives a normal application of commercial fer-
tilizer each year—equal to about 900 kilograms of a
10-10-10 fertilizer per hectare annually.
Nutrients Removed by Crop Harvest
The contribution of the higher plants as renovators
of the wastewater is readily evident when one con-
siders the quantities of nutrients, expressed in
kilograms per hectare, removed in crop harvest. Such
data indicate that the vegetative cover can contribute
substantially to the durability of a "living filter"
system particularly where a crop is harvested and
utilized. At the 5-cm per-week level of effluent irriga-
tion the harvest of corn silage removes about 179
kilograms of nitrogen and 48 kilograms of phosphorus.
Reed canarygrass, which is a perennial grass, is even
more efficient in that it removes about 457 kilograms
of nitrogen and 63 kilograms of phosphorus. The dif-
ference is primarily due to the fact that the grass is
already established and actively growing in early
spring even before the corn is planted.
The amounts of nutrients removed annually vary
with the amount of wastewater applied, amount of
rainfall, length of the growing season, and the number
of cuttings of the reed canarygrass, which is perennial
grass, is even more efficient in that it removes about
457 kilograms of nitrogen and 63 kilograms of
phosphorus. The difference is primarily due to the fact
that the grass is already established and actively grow-
ing in early spring even before the corn is planted.
The amounts of nutrients removed annually vary
with the amount of wastewater applied, amount of
rainfall, length of the growing season, and the number
of cuttings of the reed canarygrass.
The efficiency of crops as renovating agents can be
assessed by computing a "removal efficienty" express-
ed as the ratio of the weight of the nutrient removed in
the harvested crop to the same nutrient applied in the
wastewater. Average renovation efficiencies for the
silage corn and the reed canarygrass crops are given in
Table 9. At the 2.5-cm per week level of application of
wastewater, the corn silage removes nutrients
equivalent to about 334 percent of the total applied
nitrogen, 230 percent of the applied phosphorus, and
280 percent of the applied potassium. At the 5-cm per,
week level, the corn silage removed more than 100 per-
cent of the applied nitrogen, phosphorus, and
potassium.
Similarly harvest of reed canarygrass removes on
the average about 373 kilograms of nitrogen and about
50 kilograms of phosphorus. These removals are
equivalent to renovation efficiencies of 122 and 63 per-
cent, respectively.
44
-------
Table 9. AVERAGE RENOVATION
EFFICIENCY OF THE SILAGE CORN AND
REED CANARYGRASS CROPS
Variety and amount of effluent applied
Nutrient Corn Silage Pa. 602-A Reed canarygrass
1 2 2
Nitrogen
Phosphorus
Potassium
Calcium
Magnesium
Chloride
Sodium
Boron
334
230
280
38
53
26
2
10
145 '
143
130
15
27
14
1
4
122
63
117
9
19
20
1
2
TREE GROWTH RESPONSES
Red Pine - Experimental plots were established in a
red pine plantation in 1963. These plots have been
irrigated with sewage effluent during the past 12 years
at rates of 2.5 cm and 5 cm per week during the grow-
ing season (April to November). The plantation was
established in 1939 with the trees planted at a spacing
of 2.5 by 2.5 meters. In 1963 the average tree diameter
at breast height was 22 cm and average height was 11
meters.
Diameter and height growth measurements were
made annually. Average annual height growth on the
2.5-cm per week plot was 58 cm in comparison to 42
cm on the control plot. On the plot receiving 5 cm per
week, height growth continually decreased up to 1968
when high winds following a wet snowfall completely
felled every tree on the plot.
Increment cores were taken from sample trees in all
areas to determine average annual diameter growth.
Irrigation at the 2.5-cm per week level resulted in an
average annual diameter growth of 4.3 mm in com-
parison to 1.5 mm on the control, an increase of 186
percent.
White Spruce - Two experimental plots were es-
tablished in a sparse white spruce plantation on an
abandoned old-field area. The trees in 1963 ranged
from 0.9 to 2.5 meters in height. One plot has been
irrigated with sewage effluent during the past 12 years
at the rate of 5 cm per week, while the second plot has
been maintained as a control.
Average height of the trees on the irrigated plot in
1974 was 7.5 meters and ranged from 5.5 to 9.5
meters. The average height of the trees on the control
plot was 3.1 meters and ranged from 2.7 to 4.8 meters.
Over the 12-year period average annual height growth
was 60 cm on the irrigated areas and 25 cm on the
control areas, representing a 140 percent increase as a
result of sewage effluent irrigation.
Average diameter of trees on the irrigated plot was
9.5 cm in comparison to 3.6 cm on the control plot.
Measurements taken from increment cores indicated
that the average annual diameter growth on the
irrigated trees was 10 mm and on the control trees 4.5
mm representing a 122 percent increase.
Mixed Hardwoods - A hardwood forest, consisting
primarily of oak species, was irrigated with sewage
effluent at 2.5 cm per week during the growing season
and at 10 cm per week for the entire year (52 weeks).
Average annual diameter growth during the 1963 to
1974 period is given in Table 10. Application at 2.5 cm
per week produced only a slight increase in diameter
growth; however, the 5-cm per week level resulted in
an 80 percent increase. These values pertain primarily
to the oak species. Some of the other hardwood species
present on the plots have responded to a greater ex-
tent. For instance, increment core measurements
made on red maple (A. rubrum) and sugar maple (A.
sacchamm), indicate that the average annual diameter
growth during the past 12 years has been 13 mm on
the trees irrigated with 2.5 cm of effluent per week in
comparison to 2.6 mm on control trees, a 400 percent
increase in average annual diameter growth.
Table 10. AVERAGE ANNUAL DIAMETER
GROWTH IN HARDWOOD FORESTS
IRRIGATED WITH SEWAGE EFFLUENT
Weekly Irrigation
Amount
Average Diameter Growth
Control
Irrigated
2.5'
52
4.1
3.3
4.8
6.0
'Irrigated with 2.5 cm of sewage effluent weekly during growing
season from 1963 to 1974.
irrigated with 5 cm of sewage effluent weekly during the entire
year from 1965 to 1974.
RENOVATION EFFICIENCY OF FORESTS
The nutrient element content of the foliage of the Although considerable amounts of nutrients may be
vegetation on the irrigated plots was consistently taken up by trees during the growing season, many of
higher than that of the vegetation on the control plots. these nutrients are redeposited annually in leaf and
It is therefore obvious that the forest vegetation is con- needle litter rather than being hauled away as in the
tributing to the renovation of the percolating effluent; case of harvested agronomic crops.
however, its order of magnitude is difficult to estimate A comparison between the annual uptake of
because the annual storage of nutrients in the woody nutrients by an agronomic crop (silage corn) and a
tissue and the extent of recycling of nutrients in the hardwood forest is given in Table 11. It is obvious that
forest litter are extremely difficult to measure. trees are not as efficient
renovation agents as
45
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Table 11. ANNUAL UPTAKE OF NUTRIENTS
BY A SILAGE CORN CROP AND A HARD-
WOOD FOREST IRRIGATED WITH 5 CM OF
EFFLUENT WEEKLY
Corn Silage Renovation Hardwood Renovation
Nutrient Pa. 602-A Efficiency1 Forest Efficiency
kg/ha
kg/ha
N
P
K
Ca
Mg
180
47
144
30
26
145
143
130
15
27
94
9
29
25
6
39
19
22
9
4
'Percentage of the element applied in the sewage effluent that
is utilized and removed by the vegetation.
agronomic crops. Whereas harvesting a corn silage
crop removed 145 percent of the nitrogen applied in
the sewage effluent, the trees only removed 39 percent
most of which is returned to the soil by leaf fall.
Similarly only 19 percent of the phosphorus applied in
the sewage effluent is taken up by trees in comparison
to 143 percent of the corn silage crop.
WOOD FIBER QUALITY
The results of a recent study by Murphey et. al.
(1973) provides some insight as to effects of municipal
wastewater irrigation on the anatomical and physical
properties of the wood of forest trees. Wood samples
were collected from red pine and red oak trees
irrigated with sewage effluent.
They reported that sewage effluent irrigation on red
pine resulted generally in increased specific gravity,
increased tracheid diameter, decreased cell wall
thickness, and no change in tracheid length. Likewise
changes also occurred in red oak wood due to irriga-
tion with sewage effluent. They reported a five percent
reduction in the early wood vessel segment diameter.
These large barrel-shaped elements are the causes of
"picking"—the lifting of the surface of paper during
printing. The smaller, longer cells produced by
effluent irrigation might reduce this problem when us-
ing ring porous woods such as red oak for pulp. An in-
crease of wood volume occupied by the broad rays
from nine percent in the untreated xylem to 11.5 per-
cent of the wood developed during irrigation. The in-
crease in number and height of broad rays would
cause an increase in the percentage of "fines" in a
pulp mix. Increase in specific gravity and particularly
in the change in the amount of latewood from about
one-half to three-quarters of the growth ring provides
more mass of fibers per unit volume. Coupled with the
growth rate change, irrigation with municipal
wastewater results in the development of more fiber
per treated tree. The increase in fiber and vessel seg-
ment length also increased the utility of this wood for
pulp. Murphey et. al. (1973) concluded that in general
the alterations of the wood fibers resulting from
wastewater irrigation enhanced their utilization as a
raw material for pulp and paper.
ECOSYSTEM STABILITY
Ecosystems are somewhat elastic and can withstand
a certain amount of stress prior to permanent change
or collapse. Weekly application of wastewater will cer-
tainly impose a stress on the ecosystem. An unresolved
question is whether the impact will be sufficient to
cause a significant change and whether the change
will be desirable or undesirable. Regular applications
of large volumes of wastewater can turn a relatively
dry site into a moist super-humid site and a relatively
sterile site into a fertile one. Such changes may in-
fluence species composition and plant density on the
site as well as fungi, bacteria, and microorganism
types and populations. These changes, in turn, may
influence the habitat and utilization of the site by
wildlife. In general these changes are subtle and occur
over a long period of time. Since there are no
municipal wastewater spray irrigation projects in the
United States older than 12 years on which the
ecosystems have been monitored annually, we can
only conjecture the long term effects. Results from the
Penn State Project will illustrate some of the trends
observed during the past 12 years.
Forest Reproduction
Forest reproduction was tallied on milacre plots in a
mature mixed hardwood forest which was irrigated
with sewage effluent at the rate of 2.5 cm per week
during the growing season. Results indicated a drastic
reduction in the number of tree seedlings present in
the irrigated area. A pre-irrigation survey indicated
about 39,000 tree seedlings per hectare in the control
area and about 35,800 tree seedlings per hectare in the
area to be irrigated. After 10 years of irrigation,
remeasurement indicated only 4520 seedlings per hec-
tare were present in the treated area. A similar reduc-
tion was also found in the number of herbaceous
plants in the irrigated forest area. The initial survey
indicated about 213,200 stems per hectare, whereas 10
years later there were only 36,500 stems per hectare.
Forest Floor
Measurements of the forest floor (leaf litter) made
the summer of 1974 indicate that drastic changes have
occurred in relation to the accumulation and decom-
position of the forest floor. For instance, in the
hardwood forest on the Morrison soil which receives
the 5 cm per week application rate the average depth
of the forest floor in the irrigated area was 1.5 mm in
comparison to 20 mm in the control area. Forest floor
accumulations calculated on a dry-weight basis were
1206 kg/ha in the irrigated forest and 7566 in the con-
trol forest. Similar reductions in the amount of forest
46
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floor present were observed in all irrigated forest
areas.
This accelerated decomposition of the forest floor
may in time have detrimental effects on the physical
properties of the soil. Without the protective leaf litter
cover, the surface soil is more exposed to raindrop
compaction which in turn might affect infiltration
capacity. However, more important is the fact that the
forest floor insulates the surface soil during the winter
and prevents the formation of concrete frost. Without
the thick forest floor cover, the exposed mineral soil is
more susceptible to freezing which might result in sur-
face runoff and overland flow during winter irrigation
periods.
Preliminary observations have also indicated that
changes have occurred in soil invertebrate populations
(earthworms, mites, spring-tails) and in the infiltra-
tion capacity and percolation capacity of the one-foot
soil depth. These investigations are continuing and
complete results will be reported at a later date.
Old Field Herbaceous Vegetation
An old field area consisting primarily of poverty
grass (Danthonia spicata), goldenrod Solidago spp.) and
WILDLIFE
Wildlife studies were initiated on the Penn State
Project in 1971 and, hence, the results obtained to
date are largely inconclusive. Wood et. al. (1973)
reported that spray irrigation of sewage effluent at the
rate of 5 cm per week in forests and on brushland
appeared to have a favorable influence in the nutritive
value of rabbit and deer forage. Foliar analysis of
forage species indicated that crude protein, P, K, and
Mg contents all increased, whereas Ca content was
decreased.
Studies using the lead deer technique to determine
preference for or avoidance of irrigated areas indicated
that the deer used treated sites as readily as untreated
sites. During the winter period, observations indicated
that wild deer used the irrigated areas for resting and
feeding even though these areas were often ice covered
as a result of winter irrigation.
No conclusive evidence was obtained on the effects
of spray irrigation on rabbit reproduction. However,
dewberry (Rubus Flagellaris) was irrigated with sewage
effluent at the rate of 5 cm per week during the grow-
ing season since 1963. Significant changes have been
observed in species composition, vegetation density,
height growth, dry matter production, percentage
areal cover, and nutrient utilization. Average dry
matter production was 6111 kilograms per hectare on
the irrigated plot and 2027 kilograms per hectare on
the control plot. This represents an average annual in-
crease of 201 percent. Annual increases ranged from
100 to 350 percent.
Several species which were predominant prior to
wastewater irrigation have been drastically reduced in
number or have disappeared completely. For instance,
goldenrod (Solidago spp.) which had 383,000 stems per
hectare in 1963 has been reduced to about 33,600
stems per hectare. White Aster (Aster pilosus) which
had about 303,700 stems per hectare in 1963 is no
longer present on the site. The predominant species on
the irrigated plot is clearweed (Pilea pumila L.) which
covers more than 80 percent of the plot with ap-
proximately 47 million stems per hectare. This species
is typical of shaded moist sites.
HABITAT
they did find that the winter carrying capacity of the
irrigated sites exceeded that of the control areas
presumably due to the higher levels of available nutri-
tion and improved cover conditions: Rabbits trapped
on the irrigate^ areas appeared to be larger and
healthier than those on the control area which were as
much as a third lighter in weight and showed obvious
signs of emaciation.
Since public hunting areas and public gamelands
are potential disposal areas, some concern has been
expressed by sportsmen on the possible effects on
game bird reproduction. It is well known that wet spr-
ing season periods may have an adverse effect on the
survival of young broods of wild turkey and grouse.
Many of the young chicks die of pneumonia during
these cool, wet periods. An unanswered question is
whether weekly spray irrigation of wastewater will
produce the same condition.
TREE MORTALIY
In 1972 a survey was made in the hardwood forest
area on the Morrison sandy loam soil to determine the
effect of sewage effluent irrigation on mortality. This
area was selected since it is the largest (approx. 8 hec-
tares) forest stand under irrigation. Mortality was
defined as all standing dead trees. The forest stand
had received 10 cm of sewage effluent weekly during
the growing season only from 1964 to 1967; during the
dormant season only from 1968 to 1971; and 5 cm of
effluent weekly during the growing season in 1972.
The results of the survey are given in Table 12. Results
indicated that mortality was about 20 percent higher
in the effluent-irrigated forest area. There was also a
large difference in the number of living trees per hec-
tare, particularly, in the 5 cm diameter class.
Unirrigated forest areas averaged 716 trees per hectare
in the 5 cm diameter class compared to only 173 trees
per hectare in the irrigated forest areas.
Although many of these young saplings are lost
through natural suppression, a considerable number
are lost in the irrigated areas through ice breakage
during winter irrigation. The survey results indicated
that approximately 128 stems per hectare showed visi-
ble ice damage in the irrigated areas in comparison to
18 stems per hectare in the control areas. Seventy-five
percent of these trees were in the 5 cm diameter class
47
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Table 12. POPULATION AND MORTALITY IN
FORESTED STANDS IN CONTROL PLOTS AND
IRRIGATED WITH SEWAGE EFFLUENT
Diameter
class
Living trees
Mortality
Irrigated Contiol Irrigated Control
sterns per hectare
stems per hectare
5
10
15
20
25
30
35
40
173
247
99
148
99
74
5
12
716
271
198
198
123
62
17
—
136
67
49
6
—
—
—
—
104
79
12
6
—
—
—
—
Total
857
1585
258
213
and the remainder in the 10 cm diameter class. The
species most susceptible to ice damage was red maple.
A reasonable amount of ice damage must be expected
if disposal systems are to operate throughout the year.
However, ice damage can be minimized through the
proper design of the spray-irrigation system and the
use of low-trajectory rotating sprinklers (Parizek el. al.
1967; Myers, 1973).
A comparison of the results of the 1972 survey made
in the effluent-irrigated forest areas with the results of
several other forest surveys of mixed hardwood stands
on a variety of sites in central Pennsylvania indicate
that 10 years of effluent irrigation have produced no
great differences. The average number of living trees,
13 cm in diameter and greater, in the effluent-irrigated
forests was 437 stems per hectare in comparison to an
average of 382 stems per hectare in several natural
mixed hardwood stands. Mortality of trees, 13 cm in
diameter and greater, in the effluent-irrigated forests
was 55 stems per hectare in comparison to an average
52 stems per hectare in several natural mixed
hardwood stands.
GROUNDWATER RECHARGE
The amount of renovated effluent recharged to the
groundwater reservoir was estimated from data
available on the total amount to effluent and rainfall
received by the plots, and potential evapotranspira-
tion. Annual recharge ranged from 1.1 to 1.8 million
gallons per acre irrigated with an average of 1.6
million gallons. Recharge amounted to approximately
90 percent of the effluent applied at the 2 inches per
week rate. Hence it is evident that with properly
programmed application, sewage effluent can be
satisfactorily renovated and considerable amounts of
high quality water recharged to the groundwater
reservoir. In time, contributions to the groundwater of
this magnitude will certainly have a beneficial effect
on the local water table level.
MANAGEMENT PROBLEMS
Utilization of forests on the spray irrigation site
generally necessitates the use of a solid-set irrigation
system which may cause some problems. Three poten-
tial problems that may be encountered with effluent
irrigation in forested areas are (1) ice damage, (2)
windthrow, and (3) bark damage by sprinkler spray.
The ice breakage problem has already been discussed.
Bark damage by sprinkler spray can be avoided if
sprinkler nozzle pressures are operated at or less than
55 p.s.i. Nozzle pressures for the solid set system used
in the forests on the Penn State project are ap-
proximately 50 p.s.i. Little tree damage has been
observed even on small trees within a 1 meter radius of
the sprinkler head.
Windthrow of individual trees and large numbers of
trees (the 0.4 hectare red pine plot irrigated with 5 cm
of effluent weekly) has been the greatest problem.
REFORESTATION
In contrast to the utilization of an existing forest for
spray irrigation, there is also the option of using
municipal wastewater for reforestation and reclama-
tion of drastically disturbed areas such as those
resulting from strip mining operations.
In 1968 a feasibility project was initiated to deter-
mine if municipal sewage effluent and liquid digested
sludge could be used to ameliorate the harsh site con-
Weekly irrigation of sewage effluent at rates of 2.5 and
5 cm per week keep the soil moisture status near field
capacity and hence encourages the development of
shallow tree root systems. In November of 1968,
following a weekly application of 5 cm of sewage
effluent, a heavy snowfall accompanied by strong
winds resulted in the complete blow down of the 0.4
hectare plot. Since then several individual trees have
also been windthrown in the mixed hardwood forests.
Most of the trees have been adjacent to natural
forest openings, agricultural fields, roads, or power
line rights-of-way. It appears that this problem could
be mimimized if an unirrigated buffer zone 15 to 35
meters wide were left on the windward side of any
irrigated forest area. This buffer zone would provide a
wind break against prevailing winds.
AND RECLAMATION
ditions existing on many bituminous coal strip mining
spoil banks. Revegetation of many of these banks has
been unsuccessful because of high acidity, toxic levels
of iron, aluminum, and manganese, low fertility, low
moisture content, and extremly high summer surface
temperatures.
Treatment with sewage effluent and liquid digested
sludge might ameliorate these conditions. The slightly
48
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alkaline, nutrient-enriched wastewater might leach
acids and toxicants below plant rooting depth and at
the same time provide organic colloids to detoxify the
soluble iron, aluminum, and manganese. The addition
of the wastewater would also provide the necessary
moisture for vegetation survival and growth and
evaporational cooling should moderate the lethal sur-
face temperatures.
To test this hypothesis spoil material was obtained
from a bank over the lower Kittanning bituminous
coal seam in Clearfield County, Pennsylvania. This
bank was selected because it has remained barren for
23 years despite several attempts at revegetation and is
extremely acid (pH 2.0 to 3.0). Approximately 25
metric tons of spoil material were placed in each often
large boxes - 9.7 meters long, 1.2 meters wide, and 1.2
meters deep — with an open bottom having 15 cm of
sand resting on natural soil. The boxes were filled with
1 meter of spoil material. Each box was planted with
seven species of tree seedlings —Japanese larch, white
spruce, Norway spruce, white pine, European alder,
hybrid poplar, and black locust. In addition, two
species of grass (orchard grass and tall fescue) and two
species of legumes (crownvetch and birds-foot trefoil)
were broadcast seeded in each box.
Two of the boxes were untreated and maintained as
controls. The remaining eight boxes were divided into
four groups of two boxes for treatment. The four
treatments applied were: (1)5 cm of sewage effluent a
week, (2) 2.5 cm each of sewage effluent and sludge
per week, (3) 5 cm each of sewage effluent and sludge
per week, and (4) 5 cm of sludge per week. Irrigation
treatments were applied for 24 weeks during the grow-
ing season.
On the unirrigated control boxes there was com-
plete mortality of all planted seedlings and none of the
grass or legume seed germinated. Vegetation in the
treated boxes responded dramatically. Some of the
tree seedlings survived on all treated boxes. Best
overall tree seedling survival percentages were ob-
tained on the boxes which received 5 cm of effluent per
week. Under this treatment survival percentages were
65 percent for black locust, 63 percent for white pine,
40 percent for white spruce, 38 percent for European
alder, 35 percent for Norway spruce, 10 percent for
hybrid poplar, and 3 percent for Japanese larch. Black
locust had the highest survival percentages over all
treatments ranging from 65 to 85 percent. Black locust
had the best height growth of surviving species and
ranged from 10 to 35 cm although some individual
trees attained a height of 1.2 meters. Hybrid poplar
ranked second in average height growth.
Treatments were very effective in establishing a
ground cover of grasses and legumes. Growth response
of each species was measured in terms of pounds of
dry matter produced per hectare and percentage of
ground cover. Best germination and growth was ob-
tained with the combination, 5 cm of effluent and 5 cm
of sludge per week, treatment. Orchard grass and tall
fescue had the highest dry matter yields of 3625 and
2963 kilograms per hectare, respectively. It was quite
apparent from the results that sludge is a necessary
prerequisite to the establishment of grasses and
legumes from seed. The organic residue in the sludge
provides the necessary seed bed for germination.
The percentage cover of the spoil material by the
grasses and legumes on the irrigation treatments rang-
ed from 28 to 100 percent for orchard grass, 5 to 91
percent for tall fescue, 3 to 56 percent for birdsfoot
trefoil, and 2 to 58 percent for crownvetch. The max-
imum cover was obtained for all species with the com-
bination, 5 cm of effluent and 5 cm of sludge per week,
treatment. Establishment of a complete ground cover
of vegetation is highly desirable since it can result in
earlier stabilization and reduction of erosion, in earlier
mitigation of acid drainage by diminishing net
recharge through increased evapotranspiration losses,
and in the acceleration of inputs of organic residues for
detoxifying the soluble iron, aluminum, and
manganese.
In 1972 this study was expanded to evaluate more
grass and legume species. Additional boxes were con-
structed and filled with spoil material from the same
bank as the previous study. Each box was divided into
eight 120 by 120 cm foot plots. These plots were then
randomly seeded with 8 species of grasses (Garrison
creeping foxtail, Saratoga smoothbrome, reed
canarygrass, Blackwell switchgrass, weeping
lovegrass, redtop, deertongue, and climax timothy)
and 8 species of legumes (sericea lespedeza, Chemung
crownvetch, lathro flatpea, Iroquois alfalfa, Pennscott
red clover, sweet clover, Ladino clover, and Arnot
bristly locust). The boxes were irrigated for 18 weeks
during the growing season with the same combination
treatments (IE + IS, 2E + 2S) used in the previous
study.
The results indicated that treatment ameliorated
the harsh site conditions and greatly facilitated es-
tablishment of the grasses and legumes. The grasses
did much better than the legumes in both dry matter
production and percent areal cover of the spoil. Weep-
ing lovegrass and Blackwell switchgrass gave the best
growth response of the grasses with 12,395 and 5,252
kilograms of dry matter per hectare, respectively, with
the 2E + 2S treatment. Bristly black locust gave the
best growth of the legumes with 2,029 kilograms per
hectare averaged over both treatment rates. Weeping
lovegrass, Blackwell switchgrass, reed canarygrass
and deertongue gave the best percentage cover of the
spoil with 100, 100, 100 and 96 percent areal cover
respectively on the 2E + 2S treatment. Ladino clover
(99), bristly blacklocust (90), Iroquois alfalfa (90),
sericea lespedeza (90), and sweet clover (90) also gave
good cover on the 2E + 2S treatment. These species
would be the best suited for use in spoil bank stabiliza-
tion and erosion control.
49
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Dry Sludge
In 1974 a second project was initiated to investigate
the feasibility of using dry sludge to revegetate a burn-
ed anthracite refuse bank located in Scranton, Penn-
sylvania. Heat-dried sludge was obtained from the
Scranton-Dunmore treatment plant and was applied
on three experimental plots established on the bank.
Application rates were 0, 40, 75 and 150 dry metric
tons per hectare. After spreading the sludge was incor-
porated with a tractor and cultivator.
The main plots were then planted with seedlings of
ten tree species (red pine, white pine, Austrian pine,
Virginia pine, white spruce, Japanese larch, hybrid
poplar, European alder, black walnut and black
locust). Subplots were broadcast seeded with five
grass species (Blackwell switchgrass, deertongue, reed
canarygrass, tall fescue and orchardgrass) and five
legume species (bristly locust, Iroquois alfalfa, ladino
clover, Penngift crownvetch, and birdsfoot trefoil).
One of the main plots was maintained as a control
while an irrigation system was used to irrigate the
other two plots on a bi-weekly schedule during the
growing system. One plot received 5 cm of city water
bi-weekly and the other plot received 5 cm of treated
sewage effluent.
Preliminary results indicated that tree mortality
was the highest on the control plot. Best overall tree
survival was obtained with the 40 tons per hectare
sludge application rate. Average total height of sur-
viving tree seedlings is given in Table 13. Specks
which had the greatest first-year height growth were
black locust, hybrid poplar, and European alder.
Sludge applications also greatly enhanced germina-
tion and growth of the seeded grasses and legumes. In
addition, a considerable amount of volunteer vegeta-
tion invaded the sludge treated plots. The average
areal cover percentage of all vegetation (seeded species
plus volunteer vegetation) is given in Table 14. The
best vegetation establishment was obtained on the
plots treated with 40 and 75 tons of dry sludge per hec-
tare.
These results, although only preliminary, indicate
that reclamation of refuse banks can be facilitated
with the use of municipal sludge.
Table 13. AVERAGE TOTAL HEIGHT OF SURVIVING TREE SEEDLINGS IN CENTIMETERS
Sludge Application Rate
Species
White Pine
Austrian Pine
Virginia Pine
Red Pine
White Spruce
Japanese Larch
European Alder
Hybrid Poplar
Black Locust
C
12
14
17
10
25
27
41
41
64
0
W
12
15
19
12
22
25
42
31
57
E
11
14
18
12
24
27
42
29
55
C
11
12
19
10
19
29
42
80
83
40
W
12
14
18
10
21
28
44
75
76
E
12
14
17
10
25
28
48
48
70
— Dry Tons Per Hectare
C
12
15
19
12
18
26
38
96
78
75
W
10
14
18
10
24
26
58
95
94
E
10
15
16
9
29
24
59
54
102
C
15
10
—
—
21
—
19
69
55
150
W
10
13
15
10
22
27
59
95
83
E
12
19
17
9
25
27
48
76
83
C - Control
W - Water - 5 cm bi-weekly
E - Effluent - 5 cm bi-weekly
Table 14. AVERAGE AREAL COVER PERCENTAGE OF ALL VEGETATION ON THE PLOTS
Species
Seeded
Blackwell Switchgrass
Deertongue
Reed Canarygrass
Orchardgrass
Tall Fescue
Bristly Locust
Iroquois Alfalfa
Ladino Clover
Pennsift Crownvetch
Birdsfoot Trefoil
Sludge Treatment
C - Control
W - Water, 5 cm bi-weekly
E - Effluent, 5 cm bi-weekly
C
14
22
38
52
55
63
45
52
25
47
0
W
47
63
70
88
73
60
95
97
88
98
Sludge Application Rate
40
E
72
75
85
82
80
78
95
98
93
100
C
10
11
63
65
60
25
30
37
42
47
W
85
87
97
100
98
93
98
97
97
100
E
91
95
100
100
100
98
98
100
99
100
— Dry Tons Per Hectare
75
C
15
11
53
45
57
32
20
28
53
40
W
90
92
100
100
100
92
100
100
100
100
E
98
100
100
100
100
100
100
100
100
100
C
5
9
50
45
25
8
10
18
37
13
150
W
22
68
95
92
93
90
90
97
95
93
E
13
23
98
100
98
88
92
98
98
98
50
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CONCLUSIONS
Twelve years of research have indicated that the liv-
ing filter system for renovation and conservation of
municipal wastewater is feasible and that the com-
binations of agronomic and forested areas provide the
greatest flexibility in operation. Such a system is more
adaptable to small cities and surburbs than to large
metropolitan areas because of the availability of open
land close to the wastewater treatment plant, although
the land area requirement is not a major prohibitive
factor. At the recommended level of irrigation, 5 cm
per week, only 52 hectares of land would be required
to dispose of 4 million liters of wastewater per day.
Although large contiguous blocks of agricultural and
natural forest land would be the most desirable for ef-
ficiency and economy, major metropolitan areas could
utilize golf courses, playing fields, forest preserves and
parks, greenbelts, scenic parkways, and perhaps even
divided highway and beltway medial strips. Results
also indicate that municipal wastewaters might be
used to reclaim and revegetate many of the barren
bituminous strip mined spoil banks and anthracite
refuse banks existing throughout the Appalachian
region and restore them to a more esthetic and
productive state.
ACKNOWLEDGEMENT
Research reported here is part of the program of the
Waste Water Renovation and Conservation Project of
the Institute for Research on Land and Water
Resources, and Hatch Project No. 1809 of the
Agricultural Experiment Station, The Pennsylvania
State University Park, Pennsylvania. Portions of this
research were supported by funds from Demonstra-
tion Project Grant WPD 95-01 received initially from
the Division of Water Supply and Pollution Control of
the Department of Health, Education, and Welfare
and subsequently from the Federal Water Pollution
Control Administration, Department of the Interior.
Partial support was also provided by the Office of
Water Resources Research, USDI, as authorized un-
der the Water Resources Research Act of 1964, Public
Law 88-379 and by the Pinchot Institute for En-
vironmental Forestry Research, Forest Service,
USDA. Financial support for the Scranton sludge
project was provided by the Bureau of Mines, U.S.D.I.
under Grant No. G0133133.
LITERATURE CITED
Jackson, M. L. 1958. Soil Chemical Analysis. Prentice
Hall, Inc. Englewood Cliffs, New Jersey. 498 pp.
Murphey, W. K., R. O. Bisbin, W. J. Young and
B. E. Cutter, 1973. Anatomical and physical
properties of red oak and red pine irrigated with
municipal wastewater. Recycling Treated Munici-
pal Wastewater and Sludge Through Forest and
Cropland. The University Press, The Pennsyl-
vania State University, pp. 295—310.
Myers, E. A. 1973. Sprinkler irrigation systems:
design and operation criteria. Recycling Treated
Municipal Wastewater and Sludge Through Forest
and Cropland, The University Press, The Pennsyl-
vania State University, pp. 324—333.
Parizek, R. R., L. T. Kardos, W. E. Sopper, E. A.
Myers, D. E. Davis, M. A. Farrell, and J. B. Nes-
bitt. 1967. Waste Water Renovation and Con-
servation, Penn State Studies No. 23, 71 pp.
Peech, M., L. T. Alexander, L. A. Dean, and J. F.
Reed. 1947. Method of soil analysis for soil fer-
tility investigations. United States Dept. of Agric.
Circular No. 757. Washington, D.C.
Sopper, W. E. 1968. Waste water renovation for
reuse: Key to optimum use of water resources.
Water Research, Vol. 2:47-480.
Sopper, W. E. 1971. Effects of trees and forests in
neutralizing waste. In trees and forests in an
urbanizing environment, Coop. Ext. Service,
Univ. of Mass., p. 43 — 57.
Sopper, W. E., L. T. Kardos. 1973. Vegetation re-
sponses to irrigation with municipal wastewater.
Recycling Treated Municipal Wastewater and
Sludge Through Forest and Cropland. The
University Press, The Pennsylvania State Uni-
versity, pp. 271-294.
Wood, G. W., D. W. Simpson and R. L. Dressier.
1973. Deer and rabbit response to the spray
irrigation of chlorinated sewage effluent on wild-
land. Recycling Treated Municipal Wastewater
and Sludge Through Forest and Cropland. The
University Press, The Pennsylvania State Uni-
versity, pp. 311-323.
51
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The Environmental and Sociological Impact of Recycling of
Agricultural Waste by Land Use
by
Benjamin J. Reynolds
Green Valley Farms
Avondale, Pennsylvania
INTRODUCTION
New ways of disposing of animal and human
effluent are now being demanded in the United States
because of the overloading of streams, lakes and rivers,
and even our oceans, with pollutants. The nitrogen,
phosphorous and organic matter that now pollute our
bodies of water are really resources out of place. Green
Valley Farms has taken the concept of recycling, refin-
ing and utilizing these resources in a beneficial
manner to grow crops, instead of allowing these
resources to reach either the surface or ground water.
If these nutrients are allowed to reach either the sur-
face or ground water, they are then classified as
pollutants and are lost to mankind's benefit.
At the Colloquium on Primary Materials Supply
and Recycling held at Orleans la Source, France,
September 27-29, 1973, part of the general conclusion
states, "At one extreme, in the rich countries, solid
wastes amount to an average of 20 tons per person
each year. This includes about 10 tons of agricultural
waste, 8 tons of mineral wastes and more than 2 tons
of urban refuse (municipal, commercial, domestic)."
Of the waste produced per person in the highly in-
dustrialized nations, 50% is agriculturally derived.
This factor points out the great need for the recycling
of agricultural waste to maintain a clean environment
and an adequate and nutritious supply of food for the
world population. Green Valley Farms has under-
taken a research and development program to recycle
cattle wastes back to the land in order to enhance the
environment and to help provide a better and more
nutritious food supply for our neighbors.
Green Valley Farms is located in New Garden
Township, Chester County, Commonwealth of Penn-
sylvania, United States of America. This is in the
metropolitan region of the eastern United States
which is commonly termed "megalopolis" and
reaches in distance from Boston, Massachusetts, in
the north, to Washington, the Capitol of the United
States, on the south. The very location within this ur-
ban megalopolis area makes the results and accep-
tance of Green Valley Farms' concept of land use by
the community such an exciting prospect for the
future.
Short History
Green Valley Farms was established in 1709 and is
an original grant from William Penn and has been in
continuous operation for 265 years. My grandfather
purchased the farm in 1904 and it was operated by
him and my father as a dairy farm until 1945 when I
continued the operation, wholesaling the milk to the
city of Philadelphia.
The location of this farm in New Garden Township,
in a rapidly urbanizing area surrounded by a popula-
tion of 400 people, is a microcosm of almost
any metropolitan area in that it has much diversity
such as heavy manufacturing and fabricating plants,
trucking industry, the world's greatest mushroom
growing area, large horticultural greenhouses produc-
ing some of the finest roses for the metropolitan
markets, canneries, research and development
facilities, electronic manufacturing plants, an airport,
golf courses, offices and businesses, stores and subur-
ban homes in the $30,000 to $100,000 price range.
During these 70 years, the whole area has been
changing rapidly from rural to urban. As this ur-
banization came upon us, Green Valley Farms made
the decision to remain agricultural in an urban area,
and I began to develop the concept of land use to
utilize the land to its utmost agricultural capacity.
Due to the drought in 1955, the first step towards this
goal was the development of water resources by irriga-
tion ponds and the first utilization of spray irrigation
in maximizing crop production.
In 1960 we decided to process the milk and sell
directly to our neighbors from our plant and store
which we built on the farm. The slogan on the jug is
"From the blade of grass to the glass." About this time
I began to take an active interest as a township
supervisor in improving and enhancing the environ-
ment of the community. When I was elected to the
General Assembly in 1964, I continued this concern
with my colleagues in Harrisburg.
These incidents all culminated into the idea of
recycling cattle waste by establishing waste stabiliza-
tion ponds and in a beneficial and economical way
apply the animal waste to the ground through a spray
irrigation system.
Green Valley Farms recycling program renovates
the animal waste by filtering the treated effluent
through the soil. The plants utilize the pollutants, i.e.,
nutrients such as phosphorous, nitrogen, ammonia
and organic matter, as part of their food supply. When
we discussed our ecological blueprint with Dr.
Melnick of Baylor College of Medicine, Houston, Tex-
as, he likened our treatment system to a water
53
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refinery, taking a crude product (the cattle waste),
treating it in stabilization ponds as part of the primary
and secondary treatment and then finish refining the
product by applying the treated effluent to the ground
and crops, and thus extracting the final amount of
nitrogen compounds, phosphorous and organic
matter. In this manner, the plants and soil are the
final extraction process, giving us an end product of
exceptionally high quality water returned to the ac-
quifer ready to be drawn upon again for mankind's
usage.
Green Valley Farms established a research and
development program to determine the environmental
impact of land treatment on our environment. At the
same time, Pennsylvania State University was
developing "The Living Filter" concept. In 1967 we
met with Dr. Kardos and his group at the Penn-
sylvania State University and began to develop the
Green Valley Farms recycling system together with a
water quality monitoring program. With the help of
Dr. Kardos, Dr. Parizek and Dr. Sopper and the GEO
Technical Services, our design engineer of Harrisburg,
the system was developed and built in 1969 and put
into full operation in June, 1970.
RECYCLING PROGRAM OF AGRICULTURAL
WASTE
The first full application of the recycling concept
was the planting of sudan the latter part of June, 1970,
which grew four feet in ten days under the spray
irrigation treatment. Our basic raw material to be
recycled is the manure effluent discharged by two
hundred head of milking cows into two stabilization
ponds. The effluent is composed of the manure and
urine excreted by the animals, the wash water to
cleanse the concrete pads, the milkhouse and milking
parlor wastes.
This basic influent, as monitored by Dalare
Associates, in the first stabilization pond has a total
fecal coliform count of between two and four million,
which is reduced in the second stabilization pond to a
range from 240,000 to 240 fecal coliform, depending
upon sunlight and holding time. The effluent in the
lagoons has shown no NO3, but has a range between
85 to 72 parts per million of ammonia in the first and
second lagoon. The five day BOD can average as high
as 500 to 600 ppm in the first lagoon to approximately
200 ppm in the second lagoon. Dissolved solids in the
primary lagoon range from 1100 to 1200 ppm and
decrease to 800 in the secondary lagoon. Phosphates
range from 100 to 60 ppm in the first and second
lagoon.
This biologically treated effluent is applied to the
crops and woodlands by a spray irrigation system.
The results of our testing show that the growth of the
crops and the woodland removes 99.6% of the am-
monia in the treated effluent (there is no NO3 in the
stabilization ponds), as well as 99.6% of the
phosphates as PO4, 5 day BOD, total and fecal
coliform, leaving a very high quality water for use
again.
The system meets the tertiary requirements of the
Pennsylvania Department of Environmental
Resources, Delaware River Basin Commission and
the no discharge goals of the Environmental Protec-
tion Agency of the United States. We, at Green Valley
Farms, have been exceptionally pleased with the high
degree of efficiency of our refinery in the renovation of
the treated effluent.
MONITORING PROGRAM
In its research and development, Green Valley
Farms established a quality control program for its
recycling of agricultural waste which includes an ex-
tensive chemical and biological monitoring system
from the very beginning of the refining process to the
final finished product of high quality ground water
returned for man's use. The chemical monitoring
program consists of dissolved oxygen, dissolved solids,
phosphates as PO4, nitrates as NO3, ammonia plus
nitrates as N, 5 day BOD, and ammonia as N. A spec-
trograph analysis is done at periodical intervals. Also
included are aerial infrared photographs taken for
further analysis of crop growth and management.
One of the first epidemiological programs in the
country for a spray irrigation system was developed in
1972 with Dr. Joseph L. Melnick, Chairman of the
Department of Epidemiology and Virology, and
Professor Craig Wallis, Professor of Epidemiology and
Virology, Baylor College of Medicine, Houston, Tex-
as. Both gentlemen had developed various monitoring
apparatus capable of detecting one virus particle per
100 gallons of water. With this exceptionally fine
capability of monitoring, Dr. Melnick and Professor
Wallis were asked to help us with our virus monitoring
program to determine if any viruses were present that
are pathogenic to mankind. They also monitored the
ground water and the streams within our spray irriga-
tion area for any pathogenic viruses. To this date,
none have been found.
The stabilization ponds are monitored on a weekly
basis by taking samples from all areas of the pond.
Also a program to monitor for shigella and salmonella
organisms was established, including typhoid. None
have been found to date.
Green Valley Farms spent a great deal of time
designing a method of catching the treated effluent
from the irrigation sprinkler guns. This collected
effluent was put through the virus monitor. Again, no
viral pathogens, shigella or salmonella organisms were
found.
The program put in practice at Green Valley Farms
is considered one of the first of its kind in the country,
and many regulatory agencies, environmentalists,
scientists and other interested people have spent many
hours discussing the development of the virus monitor-
ing system for assuring the safety of the spray irriga-
tion procedure.
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It is our belief that the program developed for us by
the Department of Virology and Epidemiology, Baylor
College of Medicine, could be duplicated and used on
a worldwide basis to provide environmental health
monitoring in the parameters of viruses in land treat-
ment systems.
With proper monitoring, there is no longer any
reason for withholding human wastewater, properly
treated to inactivate any viral or other pathogens that
may be present, from spray irrigation. Key to the
success of such a program is (1) the use of proper
treatment to inactivate viruses and (2) the regular
monitoring to assure the community that the treat-
ment is effective.
ENVIRONMENTAL IMPACT
Recreation
Green Valley Farms is located in a community of
approximately 4,000 people which makes it a good test
model for the sociological aspects of a community's
response to a land treatment system, i.e., recreation,
visual esthetics, open space.
The upper fresh water lake has provided a fishing
area for local children and, on occasion, their parents.
The irrigated woods is a recreational and nature area
for the community around it. Many species of birds
and wildlife are found in the woodland and area im-
mediately surrounding it. The areas irrigated in the
wintertime and the ice patterns that develop from
spraying in the freezing weather provide a very pretty
panorama of a winter woodland landscape. The spray
irrigation of the woodland not only feeds the trees, but
by keeping the area natural, provides an excellent
growth of berries and seeds and nuts which birds and
wildlife feed on. This extra food supply seems to be
one of the key factors to attract and keep the wildlife in
the woodland and farming area.
In the spring and summer the wildflowers and
woodland plants, as well as the lovely woodland
foliage, create a beautiful conservation area. The
effluent from the spray irrigation is feeding the
woodland area and makes a very delightful nature
area as well as a summertime playground for the
children when they are out of school. In the fall,
sportsmen train their dogs in the general area, and
when hunting season arrives, pheasant and squirrel
are in plentiful supply. We have posted the large pond
so that the mallard ducks, canvasback and other
species as well as the Canadian geese are protected.
Horseback riding through the woods and the sur-
rounding area is a year round activity. This nature
center and wooded area is in the center of a very heavi-
ly urbanized area and actually pays revenue to the
township through a land tax. We have coined a phrase
and have used it in many of our talks and
seminars—"Taxpaying open space".
With proper planning and proper management, the
results we have seen in the last five years at Green
Valley Farms indicate very strongly that the enhance-
ment of the environment by recylcing of animal
and/or human waste provides tremendous potential
for recreational and esthetically pleasing open space
for communities and does not place a burden on the
taxpayer. Again, we see the theme of nature and man
working in harmony with each other to the greatly
enhanced benefit of mankind.
The community's response to land treatment has
been a very fine one. We feel this can be duplicated in
many areas of our country and throughout the world.
It is of prime importance that the community be told
of the environmental enhancement of a land treatment
system which is of proper design and employs good
management, — that it can be an asset to a communi-
ty by improving the enivronment as well as providing
revenue for schools and community services.
ENVIRONMENTAL IMPACT
Agriculture
Green Valley Farms has been irrigating cropland
with fresh water since 1955, and in the 1960's with the
the help of the Pennsylvania State University began to
develop a land disposal system incorporating cattle
wastes which had been treated in three stabilization
ponds to a high degree of treatment and then released
into the stream. We felt this was a tremendous waste
of vital resources (both organic and chemical
nutrients) which could be used on our land. We con-
sulted with Dr. Kardos, Dr. Parizek and Dr. Sopperof
the Pennsylvania State University who helped us
develop a living filter system and a monitoring
program for surface and ground water. This included
streams, springs, shallow monitoring wells and deep
monitoring wells.
In 1970 Green Valley Farms started an active land
treatment program which eventually evolved and
developed into "An Ecological Blueprint for Today".*
As previously stated, Dr. Melnick and Professor
Wallis of Baylor College of Medicine have made possi-
ble the most extensive public health monitoring
system for any land treatment system in the country.
As we developed our land treatment system, working
very closely with governmental agencies and the
academic community, we found to our surprise that
we were enhancing crop production to an extremely
great extent. In meeting after meeting, we had been
told that land disposal systems are good for just short
periods of time. We are happy to report that just the
reverse was happening and that our crops were mining
the fertilizer, nutrients and organic matter faster than
we could apply them. It was at this point of time that
we consulted- with Dr. Dale E. Baker of the Penn-
sylvania State University and requested his help in
developing a program that would be geared specifical-
* Copyright, 1972
Benjamin J. Reynolds, Avondale, Pennsylvania
A Manual of Waste Treatment Using Spray Irrigation
AN ECOLOGICAL BLUEPRINT FOR TODAY
55
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ly to maximizing food, crop and timber production
from a land treatment system.
We at Green Valley Farms had been interested in
the use of aerial infrared photography for a number of
years which first put us on the trail of the mining effect
of our plants. To the environmentalist this is an excep-
tionally important item of the whole concept in that
the plants utilize and renovate the applied effluent
before it can reach the ground water.
In 1972 Dr. Baker began to work with us to develop
a system of land treatment that would maximize crop
production as well as bring about the highest degree of
wastewater renovation possible. The research work
done by Dr. Baker during 1972 and 1973 proved con-
clusively that the treated effluent crops were indeed
mining the nutrients very rapidly from the soil. With
the aid of his staff, Dr. Baker is now in the process of
developing a management program which consists of
adding nutrients to balance the treated effluent. This
correctly balanced effluent results in maximum crop
production with the hybrid seeds and trees which are
available to us today.
The work accomplished by Green Valley Farms,
Dr. Baker and his colleagues indicate a number of
significant items which can have a tremendous bear-
ing on the future of mankind and the quality of life
that we will be able to enjoy. At this time, I would like
to list the very specific developments that occurred at
Green Valley Farms during 1973 and their relation to
the above comment relative to mankind.
1.) Due to our program, we were able to maximize
soybean production to 76.6 bushels per acre. The
national average is 28 bushels per acre. This high yield
was unexpected. Our check plot yielded 27.7 bushels.
Soybeans are one of the most versatile crops now
known to mankind. The production of soybeans holds
a key to the protein needs of the world. They can be
eaten as is, as a protein food, or used as a supplement
to enhance other foods, or they can be fed directly to
animals to make meat protein. The greatest threat to
the good health and nutrition of the world is the lack
of protein for our young people and our older people.
We feel strongly that this research which led us to the
discovery of an exceptional soybean production must
be amplified by many research institutions and
agriculturists the world over. When we consider the
anticipated increase of three billion people to our
world in the next 26 years, time is running out.
2.) The second development verified by extensive
research is that the treated effluent sprayed upon the
sudan grass at Green Valley Farms significantly raised
the digestible protein content by as much as 30%.
This, too, bears a direct relationship to protein for
mankind because it lessens the need for edible protein
for livestock. The sudan plant was able to synthesize
the breakdown of the ammonia in the soil from the
effluent into a much higher digestible protein content
than is normally expected from this type of grass in
our region. Again, it appears we are just beginning to
scratch the surface in the utilization of pollution in a
highly beneficial manner to mankind.
3.) The third major finding entailed the difference
between the effluent treated ear corn and the non-
treated ear corn. The nontreated corn produced a low
of 75 bushels, whereas the effluent treated corn (same
variety of seed, same field) produced a high of 152
bushels. Due to a very wet and cold spring, this corn
was replanted on June 10, which was approximately
30 days later than usual for planting in southeastern
Pennsylvania. Dr. Baker believes there is a potential of
obtaining 200 bushels per acre and, in an exceptional-
ly good year, even higher.
All test programs were significant at 95% and 99%
levels, per Dr. Baker's report.*
With this documented research, we feel very strong-
ly that if the nations of the world start immediately to
look at the use of land treatment where wanted and
applicable for maximizing crop production, we can
provide a better food supply than is now grimly pro-
jected for the future.
Grassland Farming
Results of our research and work show that
grassland farming using the application of effluent by
land treatment will become one of the most important
aspects to be considered by agronomists in the near
future for increased food production.
Much of the grasslands in the world are not suitable
to be intensively cultivated and plowed year after year
because of their topographical features. The soil con-
servation programs the world over indicate it is best to
keep much of the grassland and woodland in its
natural state in order to prevent environmental ero-
sion. These grasslands are often of poor agricultural
capabilities as compared to class 1 and 2 farmland.
The grassland hillsides can make an ideal place for the
application of both animal and human treated effluent
and sludge. Usually the best method of harvesting the
crops from grassland and steep ground is by cattle and
sheep. The alternative to raising of animals on much
of the grassland area would be to terrace the land
which would be prohibitive in both time and energy.
The terraced land would prevent soil erosion.
Our research has shown that we can raise the pro-
tein content of certain grasses, making it even more
appealing to pasture meat and milk animals on this
poorer quality ground. Working very closely together
with the soil scientists, agronomists and people active-
ly engaged in animal husbandry, we can utilize land
treatment on our grassland areas throughout the
world, thereby providing mankind with a much
greater supply of red meat than heretofore thought
possible.
*Baker, Dale E., et al., "Effect of Waste Disposal on
Crops, Soils and Water II. A case study of the use of
dairy cattle manure effluent for maximizing crop
production"
56
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Finally, the work at Green Valley Farms has shown
that timber production of both hard and soft woods
has vastly been increased by the use of treated effluent.
As the world demands more and more of lumber and
paper products, much of the marginal ground that has
gone out of production can be brought back into full
scale environmentally safe production through the
raising of trees for timber and paper by the land treat-
ment method.
SOCIOLOGICAL IMPACT
As part of this manuscript, I would like to present
an editorial from the Philadelphia Inquirer, August
24, 1974, entitled "Famine is a World Wide Problem"
with the subtitle "The Mark of Cain".
Three basic premises were pointed out in this
editorial — a climatic shift produced by the cooling of
the earth — the huge rise in the world price of
petroleum — the geometric expansion of the world's
population.
' The editorial mentions that the cooling of the earth
has caused severe droughts across much of Africa and
Asia. The extremely high price of petroleum products
has contributed drastically to the rise in price of fer-
tilizer which is so badly needed to provide adequate
supplies of nutritionally balanced food. The geometric
expansion of the world's population applies the same
demand geometrically upon our food supply.
The research and development that has been
carried on at Green Valley Farms, we feel, will have a
tremendous beneficial social impact upon the world in
the years to come. I would like to stress them in the
following manner:
1. Pollution abatement — removing the pollutants
from the animal wastes, thus providing a better and
cleaner environment.
2. Removal of the nutrients and organic matter
from the animal wastes, thus providing an excep-
tionally high quality of renovated water to be utilized
by mankind for his many needs and uses.
3. The increased crop production resulting from
items 1 and 2, (the recycling of agricultural wastes at
Green Valley Farms) showed very specifically our
ability to double corn production and triple soybean
production and vastly increase both the tonnage and
protein content of grasses.
The net effect of the ability to enhance crop produc-
tion by recylcing of agricultural wastes would be to
provide a diet substantially increased in both energy
and protein. Our civilization is very close to a diet so
low in energy and protein content that it can cause
tremendous physical and mental damage to many of
our peoples throughout the world. This not only can
happen to underdeveloped countries but, with the
changing climatic and economic factors in the world
today, can happen also to our developed countries. We
feel very strongly that our concept of recycling animal
waste can be applied as well to recycling of human
wastes with the same results and can be one of the
major factors in meeting the world food crisis that
appears to be bearing down upon us. Not only a very
beneficial environmental impact, but a beneficial
sociological impact to our world's people would seem
to be the net result of our research and development
program.
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Experience with Land Application of Wastewater and State Regulations
The Pennypack Watershed
by
Grover H. Emrich
A. W. Martin Associates, Inc.
King of Prussia, Pennsylvania
INTRODUCTION
Engineering environmental consultants have long
been concerned primarily with their own specialized
field, either storm water runoff and associated flooding
or water supply and its source from either surface or
groundwater or wastewater collection, treatment and
discharge. The fact that all of these activities are
directly or indirectly interconnected has been ignored
by most consultants in the past; however, the effects of
WATER
The major sources of water are rainfall and im-
ported water (Figure 1). The imported water may be
in the form of potable water for public water supply,
or wastewater for disposal. The major loss of water
from an area is by evaporation and transpiration. In
addition, runoff and exportation of water in the form
of potable water or sewage can represent major losses.
Once the net gain or loss has been calculated, the im-
pacts can be itemized. Unfortunately today in urban
watersheds, we find that the principal impacts are
adverse in that they represent water loss. This com-
monly causes the creation of dry streams with
associated loss of stream amenities, both aesthetic and
physical. In addition, we find that the loss of water
due to water exportation results in a loss of surface
each of these activities on the others is significant. All
of these activities are related to each other in that they
are important elements of the water balance for a
basin or a region. Disruption or displacement of water.
in this balance can have significant beneficial or
adverse effects. An evaluation of a water balance re-
quires an analysis of the sources of water, losses of
water and the impact or impacts of this net change.
BALANCE
and subsurface water supplies.
The Pennypack Watershed is a classic example of
the need to understand the water balance so that
future development is planned to have a minimal
adverse effect upon this water balance (Figure 2). The
Pennypack Watershed encompasses 56 square miles
with partially undeveloped land in the center of the
basin. The major source of water is precipitation. In
addition, water is imported from an adjoining basin to
support the demands for a potable public supply. The
major water loss from the basin is in the form of
evapotranspiration. Other water losses are surface
water runoff, and sewage that is exported to two ad-
joining basins one of which presently has a water
deficit.
Precipitation + Importation = Evaporation + Transpiration + Runoff + Exportation
FIGURE 1. NORMAL WATER BALANCE
IMPORTATION
FIGURE 2. ELEMENTS OF THE WATER BALANCE IN THE PENNYPACK WATERSHED
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THE PENNYPACK WATERSHED
Let us look at the amounts of water that constitute
the water balance in the Pennypack Watershed
(Figure 3). Annual precipitation is 44 inches or 43
billion gallons of water per year on the 56 square miles
of the watershed. Water imported into the basin for
public water supply represents an estimated 2 billion
gallons per year. The losses of water from the basin
are evapotranspiration - 28 billion gallons per year,
wastewater - 9 billion per year and a minimum of 4 to 6
billion gallons per year of base flow in the Pennypack
Creek. The system today is precariously balanced.
Heavy rainfall in the developed areas of the watershed
produce rapid runoff which results in flash flooding
along several of the tributaries and the main stem of
the Pennypack. Periods of below normal rainfall have
just the opposite effect with stream flow dropping
dramatically. In the upper reaches of the basin which
are already intensely developed and sewered, the main
stem of the Creek drys up completely. During drought
periods the central part of the basin has had stream
flows of only 3 or 4 c.f.s.
SOURCES LOSSES
Ppt Imported E-T Runoff Exported
43
28
4-6
FIGURE 3. VOLUMES OF WATER IN THE PENNYPACK WATERSHED EXPRESSED IN BILLIONS
OF GALLONS PER YEAR
EFFECTS OF
The water balance today in the Pennypack Basin is
precarious due to man's previous activities in the
basin that have upset the water balance. We are faced
with a time of decision. Shall this basin become
another urban watershed with a paved, dry, stream
bed, except in periods of storm when we have flash
flooding? Unrestricted land development in the basin
will have a negative impact on the water balance
(Figure 4). With development comes increases in im-
pervious surfaces and storm sewers. This produces
rapid collection and runoff of storm water, prohibiting
its natural recharge into the groundwater. With
development also comes a greater demand for water
supply. Available water supply in the basin is de-
creased due to a lack of recharge of the local
groundwater and a lessening of the base flow in the
stream due to the lowering of the water table.
One method to re-establish the water balance could
be the importation of water from a neighboring
watershed, but this merely shifts the adverse effects
DEVELOPMENT
from one locale to another and the domino theory
comes in to play. As one watershed becomes deficient
in water, it imports water from an adjoining water-
shed. This one then becomes deficient in water and
imports from the next watershed, and so on and so on.
With the energy crisis this country faces for the next
decade, we must also evaluate the energy re-
quirements of inter-basin transfer of water. Added to
this is the capital expenditure for water transportation
facilities. With the condition of the money market to-
day and in the forseeable future, inter-basin transport
of water becomes highly questionable. A second
method that is widely recommended is the use of
storm water for groundwater recharge. This requires
the retention of the storm water, its treatment, and
recharge to the groundwater, either by spray irriga-
tion or by seepage beds. However, in most of our ur-
ban watersheds today, undeveloped, properly located
and suitable land is nonexistent and treatment
facilities for such a system are prohibitively costly.
WATER MANAGEMENT
There are two other alternatives that may be con-
sidered. One is zero development, which is unrealistic
in urban watersheds. The second is restricted develop-
ment with concurrent land disposal of treated
wastewater (Figure 5). With restricted development
there will be fewer paved areas and a corresponding
decrease in surface water runoff and increased natural
recharge as compared to unrestricted development.
Also because of the controlled development there will
be a lessening of the demand for public water supplies.
The retention of open space will permit larger
amounts of water to infiltrate into the groundwater
than with dense land development. In addition, there
will be the beneficial effect of the spray irrigated water
which will supplement natural groundwater recharge.
Comparison of unrestricted development and
restricted development with spray irrigation will
lessen water demand, increase natural recharge and is
a most effective method for maintaining the water
balance in a basin (Figure 6).
60
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18 ••
1970
I960
1990
2000
FIGURE 4. THE EFFECTS OF UNRESTRICTED LAND DEVELOPMENT ON THE WATER
BALANCE IN THE PENNYPACK WATERSHED
re ••
16 -•
D 14 -•
12 ••
10 -•
+
+
+
1970 I960 1990 2000
FIGURE 5. THE EFFECTS OF RESTRICTED LAND DEVELOPMENT ON THE WATER
BALANCE IN THE PENNYPACK WATERSHED
61
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18 -•
16 --
C>. 14 -• NATURAL RECHARGED
12 -•
10 -•
1970
I960
1990
-H-
2000
FIGURE 6. COMPARISON OF RESTRICTED AND UNRESTRICTED LAND DEVELOPMENT
ON THE WATER BALANCE IN THE PENNYPACK WATERSHED
SPRAY IRRIGATION BENEFITS
Evaluation of the soils, geology, and hydrology of
the Pennypack Watershed indicate that it is capable of
accepting up to 4-1/2 million gallons per day or 1.5
billion gallons per year of treated wastewater. This
could create a significantly desirable effect on the base
flow in the stream and especially the tributaries near
the spray areas or could be developed as a
groundwater supply.
The average rainfall in the Pennpack Watershed is
approximately 44 inches per year. Of this amount, ap-
proximately 29 inches is evapotranspired back to the
atmosphere. The remaining 15 inches infiltrates into
the ground and eventually discharges into the stream
as base flow or else represents immediate storm runoff.
Let us assume 2 inches per week of treated wastewater
is spray irrigated onto a site. This is the maximum
permitted by Pennsylvania State Regulations today.
The 2 inches per week would represent 104 inches per
year minus evapotranspiration losses. Studies at Penn
State indicate that even during severe drought con-
ditions in 1964, almost 80 percent of the applied
treated wastewater infiltrated into the groundwater
reservoir. Assuming 80 percent of the spray irrigated
water does infiltrate, this will add 83 inches of ad-
ditional water to the groundwater reservoir every year.
This represents 2-1/4 million gallons additional
recharge per acre, per year. The Pennypack Watersh-
ed has land available that is capable of accepting up to
4-1/2 gallons per day or 1-1/2 billion gallons per year
of treated wastewater through spray irrigation. This
additional water would have a significant effect in sup-
porting base flow of the tributaries and the main stem
of the Pennypack in the middle and lower thirds of the
basin, especially during low flow periods. It also
would be possible to selectively develop water well
fields, contiguous with the spray irrigation fields. It is
estimated that 50 percent of the spray irrigated water
could be recaptured in these wells and utilized for
public water supply. The remaining 50 percent would
then supplement the base flow in nearby streams. The
physical dependency of spray irrigation systems on
open lands would thus control development within the
basin. This would result in limited water demand and
maintain multi-purpose open spaces. The spray
irrigated open spaces could be used for crop produc-
tion, wild-life sanctuaries, or recreation areas. State
regulations in Pennsylvania now encourage spray
irrigation once a week. This retention of the open
space will also permit natural infiltration of rainfall
and the recharge to the groundwater instead of max-
imizing runoff and flooding from densely developed,
paved areas.
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REGULATIONS
Regulations of the Pennsylvania Department of En-
vironmental Resources has failed to address total
water management and the water balance. Their con-
cern has been only with water quality. This has lead in
the recent past to the development of massive regional
sewage treatment plants which have extensive collec-
tion systems. Justification for this has been that it is
most cost effective. Exportation of the water through
the regional collection system has resulted in
numerous dry streams. Any improvement in quality
has been offset by significant decreases in quantity in
urban areas. In this cost effective analysis they have ig-
nored the consideration of water quantity. The fact
that regional wastewater systems export water from a
basin with a resulting negative impact on the water
balance has been ignored. This is a very vital factor.
Any cost effective analysis must include the negative
effects of water exportation. The 1972 amendments to
the Federal Water Quality Act clearly requires con-
sideration of alternative methods and mandates a
comprehensive cost benefit analysis. Proper analysis of
the cost benefits should include the cost of replacing
water exported from a basin by a regional wastewater
collection system. It should also include as a benefit,
the retention of water in a basin for re-use through
recycling of the wastewater in a spray irrigation
system. Proper analysis of cost and benefits must in-
clude the complete cycle of water from use, treatment,
discharge and return to the user in a potable form, or
the replacement costs if it is exported. With this ap-
proach for considering the water balance in a basin, it
will readily be seen that spray irrigation is the most
cost effective method for wastewater treatment in the
Pennypack Watershed.
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Experience with Land Application of Wastewater and State Regulations
Pennypack Watershed-Pennsylvania
by
Feodor U. Pitcairn
President
Pennypack Watershed Association
Bryn Athyn, Pennsylvania
Senator Henry Jackson observed recently that "all
environmental problems are outgrowths of land use
patterns."1 He might well have added that land use
patterns are substantially influenced by sewage
facilities. In all too many cases, this vital relationship
between sewage facilities and future land use patterns
has not been adequately studied or understood. A
better framework for sewer planning is urgently need-
ed if we are going to restore sanity in the future
development of the heavily populated Eastern
seaboard.
The Pennypack Watershed Association was formed
in 1970, for the purpose of providing citizens and
governments within the watershed with the means to
plan, develop, and implement a suitable program of
watershed management. Paramount in its respon-
sibilities is to insure a quality environment. This in-
cludes adequate supplies of clean water, open space
for conservation and recreation, protection of flood
plains, reduction of soil erosion, maintenance of
natural habitats, and land use planning in harmony
with natural resources.
The Pennypack Watershed encompasses a 56
square mile area, including parts of Montgomery,
Bucks, and Philadelphia Counties and eleven
municipalities. The lower 1/3 of the watershed is
within the City of Philadelphia, and is highly ur-
banized. The upper 2/3 of the watershed lies within
suburban Bucks and Montgomery counties. The up-
permost section of the watershed is undergoing rapid
urbanization, while the central portion, contrary to
typical watershed patterns, has so far remained a
unique "island of green living space."
The watershed population in just the past four years
has risen from 243,000 to 270,000 residents, an 11%
increase, which already exceeds the 1980 forecast.
Unless innovative forward looking plans are im-
plemented in the near future, the amenities and
resources of the Pennypack Watershed will be lost
forever.
The Pennypack Creek has historically been utilized
for water supply and water-based recreation. Develop-
ment pressures in combination with conventional and
outdated sanitary engineering approaches have
created severe water quantity and quality problems,
particularly during the past decade. The Pennsylvania
1. Natural History — page 76 — "The Use of Land" — April 1974
Fish Commission ceased its fish stocking program in
the Pennypack Creek in 1969, for "aesthetic reasons."
The Montgomery County and Philadelphia park
systems along the creek have erected health hazard
warnings to alert the public, and a major local water
company stopped taking its supply from the Pen-
nypack because of water quality problems. A large
sanitary waste treatment plant (6.6 MGD) in the up-
per portion of the watershed, which is presently
operating under a ban on additional connections, has
constituted a significant part of the pollution problem.
A most ominous long-range threat to the
watershed's future is posed by a proposed interceptor
pipe (4.45 MGD by 1995), designed to service two
major central watershed communities, utilizing out-
dated plans which are essentially fifteen years old. The
proposed interceptor would export wastes to a major
regional treatment plant in Northeast Philadelphia on
the Delaware River, below the mouth of the Pen-
nypack.
The interceptor would exert a negative influence on
the watershed in a number of significant ways.
First, the interceptor would export a large quantity
of water from the central watershed.-This water is es-
sential in order to preserve the proper water balance of
both the tributaries and the Pennypack Creek, es-
pecially during low-flow periods. The exportation
scheme would rob the region of a valuable future
source of local water supply. It would substantially
downgrade the recreational values of the park systems
along the Pennypack and frustrate attempts to restore
stream habitats.
An equally alarming aspect of the proposed in-
terceptor is the predictable effect that it would have in
generating more unplanned growth. It is an irony, for
example, that part of the design capacity for the
proposed interceptor assumes that a local golf course
will be developed into a residential tract, and that ad-
ditional land lying within a flood plain will be
developed for commercial purposes. The very same
pipe that is exporting the water supply, will generate
new demands for water. Thus, the future scenario
becomes clear. Remaining open space will be
threatened, existing flooding hazards will be
aggravated due to increased urbanization, ground
water re-charge will be further reduced by the addition
of impervious surfaces, and thus, generally compound
the adverse influences that already are set in motion
65
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against a quality environment for the citizens of the
Pennypack Watershed.
Turning our attention now to the upper watershed,
we see another problem emerging. The upstream
treatment plant, which has for years constituted a
major source of pollution, is now being planned to un-
dergo substantial enlargement. While this plant would
not present the water exportation problems of the cen-
tral watershed interceptor, it would in view of its very
size (12.0 MGD) severely stress the assimilative
capacity of the Creek at the single point of dis-
charge—even if very high levels of treatment are ob-
tained, which remains suspect in the light of past ex-
perience. In addition, the enlarged plant would
generate additional development pressures and the
related problems cited above. Since the upper portion
of the watershed is heavily dependent upon wells for
its source of water supply, the consequence of future
development preventing ground water re-charge
becomes even more apparent.
Meanwhile, a central watershed municipality, in
cooperation with the Pennypack Watershed Associa-
tion, has applied to the Pennsylvania Department of
Environmental Resources for a regional spray irriga-
tion system, which is in conflict with the two other
proposals cited above. I will touch on this proposal in
more detail later.
It might be useful to note at this point that all of the
problems that I have discussed here stem from one
glaring failure in the planning process. This may be
summarized as a failure to understand the principle
that all sound planning must have as its foundation a
soundly conceived program of resource management
on a regional watershed basis.
We must put an end to the chaotic conflicts which
have been engendered by a failure to see the
relationship between land use patterns, sewer plan-
ning, and resource protection. Sewer planning must
no longer remain solely in the domain of the sanitary
engineering profession. We can no longer afford the
mounting social costs that result from this kind of
tunnel vision, all too often under the guise of economic
necessity and the exercise of local rights. Are we so
blind that we can't see the need for a sounder
framework for our decisions?
While the trend during the past decade to larger
treatment plants has been described as "regional
planning" such a program can hardly be described as
resource protection, when the aftermath results in dry
stream beds, unplanned development, and costly
systems, which on the one hand export waste-water
and on the other hand re-import water through inter-
basin transfers from other regions.
The only water plans now in existence for the
watershed are the sewage facility plans for Bucks,
Montgomery, and Philadelphia Counties, prepared as
official ten-year plans for sewage facilities in accord
with the provisions of the Pennsylvania Sewage
Facilities Act (Act 537 of 1966).
These plans were all incorporated into the
Delaware Valley Regional Planning Commission's
"Regional Water Pollution Control Plan." The lofty
title disguises the reality that the plans are essentially
piecemeal, fragmented attempts to solve short-term
problems, with little attention devoted to real water
resource management issues or long-term effects.
It is interesting to note, for example, that con-
siderations for watershed-wide planning are advanced
in the recommendations of the Montgomery County
Sewage Facilities Plans . . . "that the environmental
impact of new sewage facilities be carefully
reviewed . . . that maximum benefits can best be at-
tained by implementing the principles of watershed-
wide planning."2 And yet the adopted plans almost
totally ignore these recommendations. This is not
really surprising, since the county's consultants were
limited to a $100,000 budget, an amount less than
1/10 of the 1% of the estimated cost for implementa-
tion of the sewage facilities, which was estimated to be
$66 million.
Until very recently, the full responsibility for sewer
planning has rested with the local municipalities, and
authorities. The past bears testimony to the fact that
this fragmented system of responsibility and fi-
nancing, which is user oriented, will never achieve
meaningful watershed-wide objectives. The local
municipal authority quite naturally perceives its role
as one of getting the water wastes out of the communi-
ty at the lowest possible cost. Although vested with the
major responsibility for sewer planning, the local
authority has no real responsibility or legitimate con-
cern for "the bigger picture" which includes water
resource management, land use, and watershed con-
cerns. This is an approach which has to be described
as "penny-wise and dollar foolish."
It should be acknowledged that the Pennsylvania
Department of Environmental Resources is slowly
beginning to recognize some of these problems, but
even in its new state wide, watershed-oriented sewer
studies, known as COW AMP, the major emphasis
still appears to be on water quality, with little real
focus on water quantity and resource issues.
While Public Law 92-500 represents progress, by
broadening its concern with land use and environmen-
tal issues, it, too, appears to have the defect of being
"point source" oriented, and does not adequately ad-
dress itself to water quantity and watershed manage-
ment. I am very encouraged, however, by the fact that
the EPA now requires that any application for a con-
struction grant must contain adequate data and
analysis to demonstrate that the proposed facility
reflects the most cost effective alternative over the life
of the facility. I also derive encouragement from
former Governor Peterson's1 recent public statements
that link new sewer capacity to its effect on develop-
ment. To quote Mr. Peterson: "These land use and
energy impacts are not being identified and evaluated
2. Montgomery County Sewage Facilities Plan — page X-12
66
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as part of the grant award process."3
Now let me return to the Pennypack and describe
what the Pennypack Watershed Association is doing
about these problems. The Association from its incep-
tion, has recognized the need to develop a water
resource management program for the watershed. It
received approval from the EPA in 1972 for a research
grant application entitled "Environmental Restora-
tion Using Local Watershed Planning." Unfortunate-
ly, this was never funded. Recognizing the urgency to
develop sound alternatives to the existing fragmented
sewage plans, the Pennypack Watershed Association,
with the cooperation of a central watershed
municipality, proceeded on its own.
Working with a team of consulting engineers,
hydrologists, and other specialists, the Association
had identified, in the central watershed, more than
600 acres of land eminently suited for employing spray
irrigation systems, which could handle up to 4 million
gallons per day of secondarily treated sewage. Exten-
sive discussions have been held with property owners
to obtain their participation and acceptance of the
proposal. In addition, the Pennypack Watershed
Association has identified a significant amount of ad-
ditional land, both upstream and downstream, which
would be suitable, including golf courses, and vacant
lands, which might otherwise be lost through develop-
ment. The system contemplates pretreatment by the
use of secondary treatment or aerated lagoons.
Many of the future spray irrigated sites surround a
proposed 700-acre Wilderness Corridor, of unique
value, which will be owned and operated by the
Association for educational and passive recreational
purposes. It is contemplated that the property owners
of spray sites will enter into a long-term lease with the
sewer authority, with the Pennypack Watershed
Association exercising part of the monitoring respon-
sibility.
The spray sites will serve to preserve open spaces on
a long-term basis, and will protect and enhance the
environment of the region. Conversely, if the con-
flicting interceptor proposal is approved, these open
spray sites would likely be lost to development and,
thereby, stimulate the need for additional interceptor
capacity.
Besides re-cycling needed waters and nutrients, the
spray sites will be available for multiple uses, such as
wildlife habitats, agriculture, and recreation, and will
also provide a useful buffer to the central creek-based
Wilderness Corridor.
The benefits of the proposed spray irrigation
system, conceived on a watershed-wide basis, may be
summarized as follows:
1) Water resources will be re-cycled to re-charge
ground water, maintain water balance, and augment
stream flows.
2) Future water costs can be held down by ob-
3. New York Times — page 16 — "E.P.A Is Curbing Sewer Main Sub-
sidies" — October 15, 1974
viating the necessity for tertiary treatment and for ad-
ditional water importation schemes.
3) The Living Filter techniques will improve water
quality, and quantity, and avoid heavy point source
loads.
4) Integrity of local planning will be preserved
through preservation of open space for multiple uses,
which in the alternative would stimulate new develop-
ment and create additional demands for sewer capaci-
ty-
5) There will be substantial energy savings by us-
ing natural systems versus conventional treatment
methods, and by reducing the need for chemical fer-
tilizers, and treatment chemicals.
6) The preservation of open space will minimize
flood hazards, surface run-off, pollution and siltation.
Local tax bases will not be adversely af-
fected, since the region's land values will be
enhanced and demand for costly additional
community services minimized.
7) Environmental damage due to construction of
interceptor pipe will be eliminated.
8) Stream biota and wildlife habitats will be
enhanced, air quality improved, and the recreational
and aesthetic enjoyment of the area restored.
Now let me briefly summarize where this effort
stands today. Following more than a year of constant
prodding by the Pennypack Watershed Association,
the Pennsylvania Department of Environmental
Resources has now hired a consultant to more fully
evaluate this alternative proposal, and is prepared to
go back to step one in the planning process.
Meanwhile, the EPA has set aside the conflicting
applications in the Pennypack Watershed, until a
complete evaluation is made.
We sincerely hope that the state will make a serious
effort to make a comprehensive evaluation of all the
relevant issues. The Pennypack Watershed Asso-
ciation, for its part, would far prefer state and federal
cooperation in this matter, in lieu of costly and time
consuming litigation.
Let me close by acknowledging that we recognize
that spray irrigation is not a panacea for all problems,
but we also ask the sanitary engineers to acknowledge
that their plumbing solutions have rarely addressed
themselves to fundamental resource questions. Scarce-
ly a treatment plant in the country consistently
removes the high fractions of BOD solids and
pathogens, which its design consultants promised it
would, and as a consequence, we have seen our legacy
of once sparkling streams reduced to the functional
status of open sewers. I would, therefore, ask this es-
teemed profession to look at the problems inherent
within their conventional systems, with the same
diligence that they question problem aspects of spray
irrigation. And finally, let us be honest in the discus-
sion of alternative costs to include all the costs, both
tangible and intangible, or otherwise we will continue
to perpetuate the sins of the past.
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Land Disposal of Wastewater in the Commonwealth of Pennsylvania
A Regulatory View
by
Stephen F. Curran, Jr.
Ground Water Section
Bureau of Water Quality Management
Pennsylvania Department of Environmental Resources
The land disposal of wastewater is a concept which
has developed due to increasingly stringent water
quality requirements for the discharge of wastewater
to streams and the need for adequate wastewater
treatment and disposal in areas where streams are not
readily accessible. Spray irrigation in Pennsylvania
appears to be the most popular and successful of the
various methods of land disposal; which includes
spreading by tank truck on the land, ridge and furrow
irrigation, overland flow, infiltration ponds or
trenches, and surface flooding.
Spray irrigation is the application of liquid wastes
evenly on the land surface by aerial dispersion for
treatment and or ultimate disposal. It is normally the
final stage of a wastewater treatment system, since ad-
ditional treatment is obtained through soil renovation
when the wastewater is sprayed onto the land. The
ground-water quality or quantity may in some cases
be altered but pollution of ground water or surface
water will not be permitted as a result of spray irriga-
tion. In Pennsylvania the quality of all waters,
regardless of their physical location, are subject to
regulation under the State's water pollution control
legislation.
The Clean Streams Law of Pennsylvania, as amend-
ed by legislative sessions in 1970, is the basis for rules
and regulations to protect surface water and ground
water.
"Waters of the Commonwealth shall be construed
to include any and all rivers, streams, creeks, rivulets,
impoundments, ditches, water courses, storm sewers,
lakes, dammed waters, ponds, springs, and all other
bodies or channels of conveyence of surface and un-
derground water or parts thereof, whether natural or
artificial, within or on the boundaries of this Com-
monwealth".
The law stipulates that discharges of sewage, in-
dustrial wastes, or any substance to the waters of the
Commonwealth which causes or contributes to pollu-
tion or creates a danger of pollution is declared not to
be a reasonable or natural use of such waters. No per-
son or municipality shall discharge or permit the dis-
charge of industrial waste or sewage in any manner
directly or indirectly into the waters of the Com-
monwealth without a permit, unless such a discharge
is authorized by the rules and regulations.
Since a large amount of wastewater discharged to
the land surface will infiltrate and recharge ground
water, all spray irrigation installations are considered
discharges to the waters of the Commonwealth. The
department of Environmental Resources, under the
Clean Streams Law, uses a permit system to regulate:
the location and installation of facilities, conduct of
operations, protection safeguards, and monitoring ac-
tivities for the facility . . . The Bureau of Water Quali-
ty Management of the Pennsylvania Department of
Environmental Resources is the regulatory agency
concerned with the protection of the waters of the
Commonwealth. As such, it has been involved in the
development of spray irrigation as a satisfactory
renovative tool for quite some time. We feel the point
has been reached where spray irrigation is considered
a viable alternative in the treatment and ultimate dis-
posal of wastewater. A regulatory agency has an
obligation to consider all techniques of wastewater
disposal and to assess their applicability to various
wastes, as well as their impact on the environment.
Problems which were recognized from the earliest
days of our experience with operating spray irrigation
systems indicated that regulation is needed. The im-
position of regulation, however; carries with it a
responsibility to provide guidance in the construction
and location of such facilities so that the potential user
can develop a plan satisfactory to the regulatory agen-
cy.
Spray irrigation has been going on in Pennsylvania
at least since the late 40's. The main users, here-to-
fore, have been agribusinesses, who have used spray
irrigation to dispose of their excess process water at
various locations. Spray irrigation has been used out-
side the Commonwealth for a much longer period of
time. Interest has continued to grow in the use of
spray irrigation due to its many benefits. Ap-
proximately five years ago, The Department deter-
mined that interest in the technique was so strong that
a manual was needed to guide consulting engineers
and concerned persons desiring to use spray irrigation
to meet their needs. It should be pointed out, that,
while this interest was developing, the Department
was becoming increasingly aware of the need to
protect the quality of ground water. Severe ground-
water pollution was observed from various solid and
liquid waste disposal facilities, and some facilities that
were not causing problems posed a tremendous pollu-
tion potential.
Historically, the emphasis has been to protect sur-
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face water with little or no thought given to ground
water. Ground water is not visible and as a result, is
generally overlooked (out of sight; out of mind).
Discharges to ground water and land disposal of waste
and wastewater have been considered by some to be
the ideal treatment technique because they are not
direct discharges to surface waters and, therefore;
thought not to affect surface water quality. Effective
water quality management programs cannot deal with
the surface water alone. Non-point sources of all water
in surface streams originate from either direct runoff
or ground-water discharge. During the dry times of
the year, from August to October, the stream flow
may be as much as 100% ground-water discharge. It is
obvious that the quality of surface water can only be as
good as the quality of ground water. The protection of
ground water is considerably more complicated than
that of surface waters. A direct discharge of a polluting
substance to surface water needs only be stopped and
in the matter of days or possibly months, the stream
will usually revert to its original quality. On the other
hand, water within the ground moves painfully slow
and the flow may be measured in feet per day to feet
per year. Thus, once ground water is polluted, it may
take tens of hundreds of years to restore it to its
original quality.
The Department of Environmental Resources
published its spray irrigation manual in 1972. This
manual is written for a wide audience including the
professional design engineer, earth scientists as well as
others who need to be aware of the techniques and
technology of spray irrigation. It sets forth certain
criteria primarily as guidelines, based upon the spray
irrigation of treated sewage effluent. Throughout the
manual there are numerous statements which
demonstrate the Department's intention to be flexible
and willing to consider special applications and
designs.
Spray irrigation should only be used in situations
where the wastewater contains materials of such type
and concentrations that they can be renovated in the
soil mantle and do not pollute ground water. General-
ly, the equivalent of secondary treatment must
precede the irrigation. Allowance for variability of
earth materials, spray field use, and effluent con-
stituents is considered in reviewing proposals on a site
by site basis. The prime consideration for site selection
is the ability of the organic and earth materials to
properly treat the wastewater.
Like all rapidly developing technologies, waste
treatment and disposal by spray irrigation has suf-
fered from some misunderstanding, inadequate
design, mismanagement, and misapplication, con-
versely, it shows great promise as a valuable alter-
native technique for wastewater management. A new
attitude of environmental understanding is necessary
by all potential users of spray irrigation. The key to
this understanding is the acceptance of the basic tenet
that spray irrigation must be integrated into the en-
vironment rather than imposed upon it.
REFERENCES
1. Rhindress, R., "Spray Irrigation — The Regula-
tory Agency View", Recycling Treated Municipal
Wastewater and Sludge Through Forest and Crop-
land, pp 440-453. .
2. Bureau of Water Quality Management. Spray
Irrigation Manual, Pennsylvania Department of
Environmental Resources. 49 Pages, Publi-
cation No. 31, 1972 Edition.
3. Commonwealth of Pennsylvania. Clean Streams
Law of Pennsylvania, amended through Legislative
Session of 1970.
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Overland Flow Treatment of Wastewater — A Feasible Approach
by
P. G. Hunt and C. R. Lee
Environmental Effects Laboratory
U. S. Army Engineer Waterways Experiment Station
Vicksburg, Mississippi
INTRODUCTION
We have discussed in previous chapters how
wastewater is renovated as it moves through the soil
profile at either slow or rapid rates. Numerous systems
that have been operated successfully for many years
can be cited for slow infiltration or crop irrigation and
rapid infiltration treatment methods. 10,11,12,13,14
Through years of experimentation and study, a good
understanding of the mechanisms involved in these
treatments has developed. At the risk of alienating
readers who have a different view, we would state that
no other method of advanced treatment of wastewater
has such a profound background of performance and
mechanistic theory as crop irrigation or rapid infiltra-
tion. There is no justifiable reason for these methods
to be ignored by administrators, engineers, or scien-
tists as alternatives for wastewater treatment.
Since the slow and rapid infiltration systems are
reliable and well understood, it might be questioned
as to why overland flow is needed, the rather obvious
answer is that on many soils of low permeability,
wastewater can neither penetrate nor move through
the soil profile; therefore, treatment by interaction
with the soil mantle is not possible. This lack of
penetration and movement can result from a number
of conditions, but the most common are low hydraulic
conductivity in heavy textured soils and barriers of
various types within the upper 3 ft of soil profiles. Slow
and rapid infiltration systems will not function well in
these situations. However, these are the soil conditions
that are required for overland flow treatment.
In contrast to slow and rapid infiltration, the treat-
ment of wastewater on soils of low permeability by
overland flow has not been well understood in the
past. However, in recent years we have begun to un-
derstand to a much greater extent how overland flow
systems function. We can see an analogy to the
development of rapid infiltration. While these are
similarities between slow infiltration and rapid in-
filtration, rapid infiltration systems will only function
if the soil profile is oscillated between significant
periods of aerobic and anaerobic conditions.1 This is a
condition not obtained in classical slow infiltration or
crop irrigation systems where prolonged anaerobic
periods would cause soil clogging and crop
damage.8|16'17 The potential of rapid infiltration sys-
tems became evident only after it was recognized
that these systems functioned differently than crop
irrigation systems but on very understandable and
manageable principles. Similarly, overland flow
systems must be constructed and operated differently
from either slow or rapid infiltration systems in order
to realize the potential for treating wastewater on soils
of low permeability.
The successes of a limited number of overland flow
systems and the research models that respond as
predicted by theory lead us to the conclusion that
overland flow is a feasible approach to the advanced
treatment of wastewater in many areas. The following
sections present an overview of system operation and
theory for overland flow treatement of wastewater.
WHAT IS OVERLAND
A schematic representation of an overland flow
system is depicted in Figure 1. In an overland flow
system, the wastewater is applied at the top of gentle
sloping hills and is allowed to flow over the soil surface
down to the collection channels. Note that treatment
is represented as an intimate interaction among the
soil surface layer, surface organic mat, plants, and
microorganisms. The common length of slope is 100 to
300 ft, and normally the system is employed on slopes
ranging from 2 to 8 percent.3 Application rates are
low, generally less than 0.5 acre-in. per day, but
wastewater is applied for five days per week. Thus
weekly application rates are approximately 2.5 acre-
in. These rates are comparable to those used on slow
infiltration-crop irrigation systems. The ability to
monitor wastewater as it leaves the treatment site is an
FLOW TREATMENT?
especially valuable characteristic of overland flow
systems. Most of the treated wastewater is availalbe at
central collection channels for quality determinations
and for discharge or other desired uses.
A good example of an overland flow system is the
Campbell Soup Company's plant at Paris, Texas
(Figures 2,3, and 4). The lush grass growth and sloped
surface are shown in Figure 2. During wastewater
applications, a film of water moves across the soil sur-
face as shown in Figure 3. It should be noted that this
film of water moves over the soil surface and through
an organic mat that is predominantly composed of
plant residue and grass roots that grow on or near the
soil surface. This organic mat is believed to be very im-
portant to both the biological and chemical func-
tioning of the system. The point discharge of treated
71
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\
\
\
\
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FIGURE 2. GENERAL VIEW OF AN OVERLAND FLOW TREATMENT SITE.
(HOEPPEL, HUNT, AND DELANEY4)
FIGURE 3. CLOSE-UP OF AN OVERLAND FLOW TREATMENT SITE.
(HOEPPEL, HUNT, AND DELANEY4)
73
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FIGURE 4. WATER-MONITORING SITE FOR TREATED WATER LEAVING THE
OVERLAND FLOW TREATMENT SITE.
(HOEPPEL, HUNT, AND DELANEY4)
wastewater and the monitoring station for this system
are shown in Figure 4. With overland flow it is possi-
ble to have a point discharge from a land treatment
system without underdrainage. As with other point
discharge systems, the quality of treated wastewater
can be easily determined and monitored.
SUPPORT FOR THE FEASIBILITY OF
OVERLAND FLOW TREATMENT
Operating Systems
The strongest support for overland flow treatment
comes from the Campbell Soup Company's treatment
system in Paris, Texas. This system has been
operating for ten years in a satisfactory manner.3 It
was shown by an Environmental Protection Agency
(EPA) study6 to have high nitrogen and phosphorus
removal as well as very good BOD removal. The
reasons for this good wastewater treatment have been
somewhat nebulous. In the past, the treatment at
Paris, Texas, has been viewed rather lightly and often
attributed to rather peculiar conditions that might ex-
ist at the site or to physical filtering of the wastewater.
It has also been suggested that the wastewater was
entering the soil and emerging some number of feet
down the slope of the soil. Gaseous loss of ammonia or
a trickling filter type of reaction has also been pro-
posed by Hunt.5 In 1968 it was proposed that nitrogen
treatment on such a system was functioning by
massive denitrification.6 This resulted in a controversy
that is still not completely resolved. Some of the more
penetrating questions that have evolved are how does
denitrification, an anaerobic process, occur on the soil
surface simultaneously with nitrification and how do
plants that require oxygen survive in an anaerobic en-
vironment. Initially, these two phenomena seem to be
mutually exclusive, but after consideration of the
plant, chemical, and biological processes of a rice field
or marsh ecosystem, they do not seem so incompati-
ble. These points will be developed more intensively in
the section on theoretical support. However, to con-
sulting engineers and city planners, the most im-
pressive facts about the Campbell Soup Company's
Paris, Texas, operation are that the system cleans
cannery wastewater to better than secondary levels
and that it has operated for some ten years in a
satisfactory manner from an engineering standpoint.
Research Model Performance
In addition to the Campbell Soup Company's Paris,
Texas, system, Thomas16 has done a considerable
amount of research into the treatment of raw and
primary wastewater by overland flow. He has general-
ly found the system to give satisfactory treatment of
these wastes. However, in 1972, when research was
started at the Waterways Experiment Station (WES)
74
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on overland flow, there was no experimentation nor
use of secondarily treated wastewater in overland flow
systems. The initial experimentation at WES was
designed to investigate the principles of overland flow
treatment and to test the advanced treatment of secon-
darily treated wastewater by overland flow.
Carlson et al.2 and Hoeppel et al.4 have reported on
the initial research at WES on overland flow. Their ex-
perimentation was conducted on 5- by 10-ft and 5- by
20-ft grass-soil models in a greenhouse. These models
were built of plywood and painted with an epoxy con-
oglaze. Two models were filled to a depth of 6 in. with
Susquehanna clay, a kaolinitic soil that is prevalent in
the southeast, is high in iron and aluminum, and is
low in pH and cation exchange capacity. The soil was
placed in these models in 1-in. layers and compacted
with a 5-psi weight before the next layer was applied.
The models were then sodded with reed canary grass,
tall fescue, bermuda grass, and ryegrass. One of the
models was constructed on a 2-percent slope, and the
other had an adjustable slope of 0 to 10 percent
(Figure 5).
A third model, built in a similar manner, was 10 ft
long and fixed at a 2-percent slope. The soil and grass
for this model were obtained from the spray field at
the Campbell Soup Company's Paris, Texas, system
in approximately 12- by 12- by 10-in. blocks;
transported to Vicksburg, Miss.; and placed into the
model.
The wastewater used in these studies had been
secondarily treated and chlorinated and normally had
nitrogen contents of 14 to 18 ppm of total nitrogen and
phosphorus contents of 12 to 14 ppm. The source of
wastewater was originally a package treatment plant
at a local motel, but wastewater was later obtained
from the Vicksburg municipal treatment plant, a
trickling filter system, shortly after it was operative in
1974. Concentrations of total nitrogen and
phosphorus from the Vicksburg treatment plant have
generally been 15 to 20 ppm and 8 to 12 ppm, respec-
tively.
Initially the wastewater applied on the model con-
taining the soil from Paris, Texas, was amended with
sucrose to provide an organic carbon source similar to
that on the cannery wastewater. This was done to en-
sure an operating system on which detailed studies
could be conducted. Wastewater on the Susquehanna
clay model was not amended with sucrose, but it was
amended with heavy metals (cadmium, copper, lead,
manganese, nickel, and zinc) to simulate a municipal
system.
Wastewater was applied at the upper slope of each
model at volumes of 0.5 acre-in. per day during a 6-hr
application period for five days per week. No
wastewater was applied over the weekend. Runoff,
subfiow, and surface samples of effluent, as well as
grass and soil samples, were collected and analyzed
periodically.
During this initial 12-week study period, 100, 95,
91, and 75 percent of the ammonium, nitrate, organic
nitrogen, and phosphorus, respectively, were removed
from the wastewater and retained by the Susquehanna
clay model. The model also retained over 90 percent of
the trace elements, cadmium, copper, manganese,
lead, and nickel, applied in the wastewater. The
nitrogen was hypothesized to be removed from the
runoff effluent by soil adsorption, plant uptake, and
denitrification. Trace element and phosphorus
removal from wastewater was hypothesized to have
been primarily absorbed by soil and organic matter.
These results from greenhouse model studies are
similar to those observed in the field systems in most
respects. One of the surprising similarities has been
the gradient of grass growth. When overland flow
systems are functioning properly, nitrogen will often
be stripped from the wastewater before it reaches the
collection channel.6 On such slopes the grass growth
responds to the nitrogen concentration and produces a
grass-growth gradient. In extreme cases the grass at
the lower end of the slope may suffer from lack of
nitrogen. Such gradients have not only been observed
in our 10- and 20-ft models (Figure 6), but also in 18-
in.-long miniature models.
Additionally, treatment efficiency has been found to
decrease with increased slope in both field and model
studies. Our model studies have generally shown
nitrogen treatment to decrease linearly with a
geometrical increase of slope between 2 and 8 percent
(P.G. Hunt, unpublished data). We believe this to be
attributable to decreased residence time of the
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Figure 5. Longitudinal section of the overland flow wastewater treatment model.
(Carlson, Hunt, and Delaney2)
75
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FIGURE 6. WASTEWATER MODEL 43 DAYS
AFTER START OF TREATMENT. GRASS
HEIGHT REACHED 20 TO 40 CM IN UPPER
10 FT (3.05 M); PRACTICALLY NO INCREASE
IN HEIGHT AND ZERO NITROGEN CONTENT
IN SURFACE WATER BEYOND 15 FT (4.57 M).
(CARLSON, HUNT, AND DELANEY2)
wastewater on the steeper slopes. This decreased
residence time can also be induced by higher applica-
tion rates, and none of our models have yet been able
to treat satisfactorily wastewater applied at a rate of 1
acre-in. during a 6-hr application period. Studies at
Pennsylvania State University have shown complete
nitrogen treatment failure when very high rates were
applied (E.A. Myers, Pennsylvania State University,
personal communications).
A significant correlation of both ammonium and
nitrate removal to flow rate has been found (Figures 7
and 8). Note that nitrate removal is affected more by
flow rate than ammonium removal. In general we have
found better nitrogen treatment when the wastewater
contained ammonium rather than nitrate nitrogen.
The equations of Figures 7 and 8 should not be used
for general predictions, since they are limited to the
conditions of the model at a particular time during ex-
perimentation.
As much as 75 percent of the phosphorus applied in
secondary municipal wastewater can be removed by
overland flow systems operating at a 2-percent slope
with an application rate of 0.5 acre-in. during a 6-hr
period. This treatment efficiency has been obtained
for approximately ten years at the Campbell Soup
Company's cannery at Paris, Texas. The soil has been
shown to account for most (69 percent) of the
phosphorus removal capacity, while the grass con-
tained a smaller fraction (6 percent) of the phosphorus
removed from the wastewater. The key to phosphorus
removal from wastewater is contact time and degree of
I3
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O
NH*= o.i491 + (0.00495)* (FLOW RATE)
^DENOTES SIGNIFICANCE AT p < 0.05
40 80 120
RUNOFF FLOW RATE, ml/MIN
160
200
FIGURE 7. SIMPLE LINEAR REGRESSION ANALYSIS FOR NITRATE IN SURFACE RUNOFF.
(HOEPPEL, HUNT, AND DELANEY4)
76
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0)
*
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<
cr
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z
o
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NO:=I.5223 + (O.OI246)* (FLOW RATE)
O
"DENOTES SIGNIFICANCE AT p<0.05
40 60 120
RUNOFF FLOW RATE, ml/MIN
160
200
FIGURE 8. SIMPLE LINEAR REGRESSION ANALYSIS FOR AMMONIUM IN SURFACE RUNOFF.
(HOEPPEL, HUNT, AND DELANEY4)
interaction of wastewater with the grass-soil complex.
The longer the contact time, the better the phosphorus
removal. Applying 0.5 acre-in. of wastewater in 18 hr
rather than 6 hr improves phosphorus removal from
wastewater to over 80 percent (C.R. Lee, unpublished
data); the converse has also been observed. Increasing
the volume of wastewater application from 0.5 acre-in.
to 1 acre-in. lowers treatment efficiency at both 6- and
18-hr application periods (C.R. Lee, unpublished
data).
Another important factor affecting the treatment ef-
ficiency of phosphorus removal from wastewater is the
slope of the land. At slopes of 2 percent, treatment ef-
ficiency has been good with 0.5 acre-in. of wastewater
applied in either 6 or 18 hr. Treatment efficiency
decreased at slopes of 4 and 8 percent (C.R. Lee, un-
published data). As the slope becomes steeper, smaller
volumes of water should be applied and longer
application periods should be used. These data again
point out the importance of allowing the wastewater to
interact sufficiently with the grass-soil complex of
overland flow systems in order to remove and fix
phosphorus from the wastewater.
Overland flow models effectively removed heavy
metals from wastewater. More than 90 percent of the
applied heavy metals, such as zinc, manganese, cad-
mium, nickel, and copper, and as much as 86 percent
of the applied lead have been removed from
wastewater. Usually these metals are fixed in the soil
within 10 ft from the point of wastewater application
(Figure 9). No adverse effects on the growth or
appearance of grass have been observed for the past
two years of treatment on greenhouse models.
However, the heavy metals appear to be held in the
surface organic layer (C.R. Lee, unpublished data).
Their concentration in this layer may become a
problem after a period of time. One obvious way in
which the concentration of heavy metals in the surface
organic mat could be reduced would be by plowing
the layer into the soil. Additionally, the authors
believe that a considerably better job of point source
control of heavy metals would greatly reduce their
concentration in secondarily treated wastewater.
Further research into the long-term fate of heavy
metals in overland flow systems and the best methods
of managing the system for heavy metals is needed.
Theoretical Support
The treatment of nitrogen by overland flow in both
models and field studies has been good. There have
apparently been considerable losses of nitrogen to the
atmosphere through denitrification. Initially this is a
hard statement to believe. It would appear that the
soluble nitrate and ammonium nigrogen would move
rapidly over the surface without treatment. However,
the most paradoxical question is how does denitrifica-
tion (a distinctly anaerobic process) and nitrification
(a distinctly aerobic process) occur on the soil surface
or within the surface water simultaneously? As a
result of this paradox, many engineers and scientists
77
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DOWNSLOPE DISTANCE, FT
FIGURE 9. HEAVY-METAL CONCENTRATIONS IN SURFACE WATER FLOWING OVER
SUSQUEHANNA CLAY. (CARLSON, HUNT, AND DELANEY2)
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FIGURE 10 OXYGEN PROFILE IN FLOODED SOIL. (AFTER PATRICK AND MIKKELSEN7)
(REPRINTED FROM FERTILISER TECHNOLOGY AND USE)
78
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SULFATE
FERRIC
IRON
NITRATE
OXYGEN
-300
-100
+ 100
+300
+400
+500
+600
OXIDATION-REDUCTION OR REDOX POTENTIAL, MILLIVOLTS
(CORRECTED TO pH 7)
FIGURE 11. RANGE OF REDOX POTENTIALS AT WHICH SELECTED CHEMICALS DOMINATE
THE SYSTEM. (AFTER PATRICK AND MIKKELSEN7)
(REPRINTED FROM FERTILISER TECHNOLOGY AND USE)
have dismissed overland flow as something slightly
less than a hoax.
It is the authors' hope that the following theory of
overland flow treatment will enable the reader to un-
derstand how an overland flow system functions
rather than simply to accept it in a type of religious
faith in Mother Nature's processes. It is also hoped
that the information and evidence will be convincing
enough that planners, consultants, and concerned
groups will make realistic assessments of the possibili-
ty of treating wastewater on soil of low permeability.
It is the authors' view that overland flow systems
function chemically and biologically in a manner quite
similar to a flooded rice field. The chemistry of soils
under rice cultivation has been studied extensively.9
The schematic of Patrick and Mikkelsen7 presented in
Figure 10 is quite good for our discussion. If one
follows the oxygen concentration curve at the top of
the figure, there is an initial drop in oxygen concentra-
tion at the water surface due to the reduced diffusion
rate and increased oxygen demand. At the soil surface
and in the oxidized layer, there is another drop in ox-
ygen concentration associated with the increase in ox-
ygen demand of microorganisms and a more tortuous
diffusion path. At some depth in the soil, depending
upon the oxygen demand, soil texture, and duration of
flooding, the oxygen concentration approaches zero.
In an overland flow system, the depth at which oxygen
is absent may be only a fraction of a millimeter.
Once the system has consumed the oxygen, a good
measure of the chemical state of the system is the
oxidation-reduction potential, Eh. In Figure 10 the Eh
is shown to be above +400 mv when oxygen is present
and to drop to -250 mv with depth after the oxygen is
consumed. According to numerous studies, Eh can tell
us a great deal about the condition of a soil. The
system is particularly well presented by Patrick and
Mikkelsen7 (Figure 11). In this figure the Eh of a
system is presented as being dominated and poised by
a particular chemical and remaining poised at the
potential of that chemical until it is consumed. In this
case it is shown that the nitrate ion poises the Eh at
approximately +250 mv. When NO3 is consumed, the
potential is dominated by Mn+\ Fe+3, and SO4~2,
respectively. It is both interesting and fortunate that
the SO4~2 to S~2 conversion occurs under rather harsh
reducing conditions. Thus the oscillation of flooded
and drying conditions minimizes the reducing con-
ditions, Eh drop, and the odors associated with sulfur
under reduced conditions.
Figure 12 illustrates the results of an Eh monitoring
of one of our greenhouse models. The plotted values
are means of ten locations. Two very interesting facts
were discovered. First, if the value of +320 mv is used
as the unstable point for nitrate at pH5, the model is
definitely under excellent denitrifying conditions at
the 5-mm depth during wastewater application
periods. These denitrifying conditions could easily ex-
ist at a fraction of a millimeter into the soil or in the
organic layer. Second, during the drying period, the
Eh rose above the nitrate potential into the ox-
ygenated region at the 5-mm depth and became more
oxidized at the 13-mm depth. It is also interesting that
upon application of wastewater, the Eh dropped
rapidly into the denitrifying area. Proof of the ex-
istence of an overlying aerobic zone is found in the fact
that nitrification in the flowing wastewater proceeds at
a rapid pace even when highly reduced conditions ex-
ist at 5-mm soil depth.
In order to verify the Eh responses in an overland
flow system, we went to the Campbell Soup Com-
pany's Paris, Texas, plant to conduct a field experi-
ment. In that study we monitored two spray areas at
three distances down the slope and three soil depths at
each location. Measurements were made five times per
day for two weeks. The data from this study are un-
79
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•APPLICATION PERIODS
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UNSTABLE
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-MM DEPTH
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20
40
60
80
100
120
HR
TIME,
FIGURE 12. REDOX POTENTIAL OF THE SUSQUEHANNA CLAY DURING A WASTE WATER
APPLICATION-DRYING CYCLE. (CARLSON, HUNT, AND DELANEY2)
published at this time. However, it can safely be said
that the condition of the soil on this system was under
denitrifying conditions during wastewater application
periods. With allowances for precipitation, it can also
be said that the system generally oscillated between
oxidized and reduced conditions similar to that
observed on our greenhouse models.
Instead of the "aerobic-anaerobic double layer"
theory, it might be conjectured that an overland flow
system functions similarly to a trickling filter, with the
exception that flow is horizontal rather than vertical.
In such a system, the algal mat that sometimes forms
on the soil surface would be important. However, ex-
perience at the Campbell Soup Company's overland
flow system in Paris, Texas, has shown algal mats to
be detrimental (Mr. Charles Neely, Campbell Soup
Company, Paris, Texas; personal communication).
Additionally, algal mats have been found to decrease
nitrogen treatment efficiency in model studies at the
WES.4
In an algal mat study, grass on one-half of a 5- by
10-ft model containing soil from the Campbell Soup
Company's Paris, Texas, system was cut and main-
tained at a low enough height to allow an extensive
algal mat to form. The mat was maintained for ap-
proximately six weeks. During this time the treatment
efficiency for nitrogen decreased on the side covered
with algal growth. A very puzzling point concerning
this reduction in treatment was that both nitrate and
ammonium were flowing across and off the models.
This was unexpected because ammonium should have
been nitrified to nitrate if the soil was too oxidized and
nitrate should have been removed through denitrifica-
tion if the system was too reduced. It might be said
that the system was simultaneously failing from both
directions.
A hypothesis of what was occurring on the model
and why algal mats are detrimental to overland flow
systems is illustrated in Figure 13. The algal mat is
hypothesized to act as a physical barrier against the
free diffusion between the aerobic-anaerobic layers.
Above the mat nitrogen is pushed to the nitrate form
through mineralization and nitrification. The nitrate
then flows on the surface of the algal mat and off the
model. Below the algal mat the nitrate is denitrified,
but very little nitrogen reaches the nitrate form
because the anaerobic conditions block nitrification
and the algal mat barrier blocks the free diffusion of
nitrate. In such a combination, ammonium ac-
cumulates, moves down the slope under the algal mat,
and flows off the system. Failure of the system in this
manner supports the "aerobic-anaerobic double
layer" theory that both aerobic and anaerobic zones
coexist and that diffusion between them is free in
operating overland flow systems.
80
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FIGURE 13. CROSS SECTION OF A FLOODED SOIL. (HOEPPEL, HUNT, AND DELANEY4)
APPARENT OPERATIONAL AND DESIGN
PROBLEM AREAS FOR OVERLAND FLOW
One of the first considerations in building an
overland flow system is to obtain a slope that will
allow sufficient residence time to provide adequate
treatment. Generally slopes less than 8 percent are
required. In addition, the slope surface must be
smooth to allow for the uniform flow of wastewater
over the soil surface. Unfilled channels cause treat-
ment problems and may start erosion. To obtain these
slopes and surface conditions, considerable earthwork
may be necessary. The overland flow system used by
Campbell Soup Company in Paris, Texas, for in-
stance, has had both timber clearing and soil cut-and-
fill operations in its construction. Insufficient prepara-
tion of an overland flow treatment site is no less a
problem than underdesign of a settling basin or
clarifier in a standard treatment plant.
Since a cover crop is an integral part of the overland
flow treatment and an erosion retardant, a good
vegetative cover is essential. Reed canary grass has
been used most extensively on overland flow systems
and at present appears to be the best all-around cover
crop. However, the major characteristic that the cover
crop must have is the ability to live in a reduced wet
soil profile. Many plants such as rice are capable of
transporting oxygen from their leaves to their root
systems and are thus able to live quite well in reduced
soils. Whether or not this is the mechanism whereby
reed canary grass survives in a reduced soil is of
academic interest for this report. It can be very con-
fidently stated, however, that a plant that requires an
aerobic soil profile will not be an adequate cover crop
for an overland flow system.
Cold weather is another serious concern. Microbial
processes are a significant component in overland flow
processes, and their rates are reduced under cold con-
ditions. The formation of ice will most definitely
adversely affect treatment performance, and a reser-
voir may be necessary to hold wastewater during the
adverse weather periods.
Even with the proper soil preparation, plant cover,
and weather conditions, the most common mistake
made on land treatment of wastewater systems
probably is either hydraulic or chemical overloading.
Overland flow systems are slow rate systems; volumes
of greater than 1/2 acre-in. per day have generally
been found unsatisfactory. In addition, the rate at
which a given volume of wastewater can be treated
each day will vary with slope and other factors that
affect treatment efficiencies.
81
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COST OF OVERLAND FLOW SYSTEMS
Cost of overland flow systems has been cited by
Gilde et al.3 at approximately $1000 per acre in 1969.
More recent figures suggest a cost of approximately
S2000 per acre (Charles Pound, Metcalf and Eddy,
personal communications). However, for further
detailed information the reader is referred to Mr.
Pound's chapter in this manuscript and to an EPA
report on the cost of land treatment systems by Met-
calf and Eddy that will be released in 1975 for detailed
cost Figures for overland flow and other forms of
wastewater treatment via land application.
PRESSING NEEDS FOR OVERLAND FLOW
TREATMENT OF WASTEWATER
The major need for public acceptance and use of
overland flow treatment is the construction of several
demonstration systems in various parts of the United
States. These systems would provide the data
necessary to refine designs and make them less conser-
vative and, thereby, more cost effective. The authors
would hasten to add, however, that even the conser-
vative designs may be more cost effective than many
other types of advanced wastewater treatment
systems. Therefore, administrators, engineers, and
scientists should seriously consider the land applica-
tion system that suits their particular soil conditions,
even if their soils are sloped and of low permeability.
They should also bear in mind that overland flow
systems, just like lagoons, trickling filters, or rapid in-
filtration systems, function properly when they are
designed on operational principles.
BIBLIOGRAPHY
1. Bower, H. 1973. Renovating secondary effluent by
groundwater recharge with infiltration basins, p.
164-175. In W. E. Sopper and L. T. Kardos (ed.),
Recycling treated municipal wastewater and
sludges through forest and cropland. The Penn-
sylvania State University Press. University Park
and London.
2. Carlson, C. A., P. G. Hunt, and T. B. Delaney, Jr.
1974. Overland flow treatment of wastewater.
U.S. Army Engineer Waterways Experiment Sta-
tion. Miscellaneous Paper Y-74-3. p. 63.
3. Gilde, L. C., A. S. Kester, J. P. Law, C. H.
Neeley, and D. M. Parmelee. 1971. A spray irriga-
tion system for treatment of cannery wastes.
WPCF; 43:2011-2025.
4. Hoeppel, R. E., P. G. Hunt, and T. B. Delaney,
Jr. 1974. Wastewater treatment on soils of low
permeability. U.S. Army Engineer Waterways
Experiment Station. Miscellaneous Paper Y-74-2.
p. 84.
5. Hunt, P. G. 1972. Microbial responses to land dis-
posal of secondary-treated municipal-industrial
wastewater. p. 77-93. In Wastewater management
by disposal on the land. U.S. Army Cold Regions
Research and Engineering Laboratory. Special
report 171.
6. Law, J. P., R. E. Thomas, and L. H. Myers. 1969.
Nutrient removal from cannery wastes by spray
irrigation of grassland. FWPCA. Water Pollution
Control Series 16080. 73 p.
7. Patrick, W. H., Jr. and D. S. Mikkelsen. 1971.
Plant nutrient behavior in flooded soil. p. 187-215.
In Fertilizer technology and use. 2nd ed. Soil Sci.
Soc. Am. Madison, Wis.
8. Patrick, W. H., Jr., R. D. Delaune, and R. M.
Engler. 1973. Soil oxygen content and root
development of cotton in Mississippi River
alluvial soils. Louisiana State University
Agricultural Experiment Station Bulletin No. 673.
28 p.
9. Ponnamperuma, F. M. (Moderator). 1965. The
mineral nutrition of the rice plant. The Johns
Hopkins Press, Baltimore, Md. 494 p.
10. Pound, C. E. and R. W. Crites. 1973a.
Wastewater treatment and reuse by land applica-
tion - Volume I - Summary. EPA Technology
Series 660/2-73-006a.
11. Pound, C. E. and R. W. Crites. 1973b.
Wastewater treatment and reuse by land applica-
tion - Volume II. EPA Technology Series 660/2-
73-006b.
12. Reed, S. (Coordinator). 1972. Wastewater
management by disposal on the land. U.S. Army
Cold Regions Research and Engineering
Laboratory. Special Report 171. p. 183.
13. Sopper, W. E. and L. T. Kardos (ed.). 1973.
Recycling treated municipal wastewater and
sludge through forest and cropland. The Penn-
sylvania State University Press. University Park
and London.
14. Sullivan, R. H., M. M. Cohn, and S. S. Baxter.
1973. Survey of facilities using land application of
wastewater. EPA 430/9-73-006. p. 377.
15. Thomas, R. E., W. A. Schwartz, and T. W. Ben-
dixen. 1966. Soil chemical changes and infiltra-
tion rate reduction under sewage spreading.
SSSAP 30:641-646.
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16. Thomas, R. E. 1973a. Spray-runoff to treat new Recycling treated municipal wastewater and
domestic wastewater. International Conference sludge through forest and cropland. The Penn-
on Land for Waste Management. 1-3 October, sylvania State University Press. University Park
Ottawa, Canada. and London.
17. Thomas, R. E. 1973b. The soil as a physical filter.
p. 38-45. In W. E. Sopper and L. T. Kardos (ed.).
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Infiltration-Percolation Systems
by
Herman Bouwer
U.S. Water Conservation Laboratory
Agricultural Research Service
U.S. Department of Agriculture
Phoenix, Arizona
INTRODUCTION
Infiltration-percolation systems, commonly called
high-rate systems, are land treatment systems
whereby municipal or other wastewater is applied at
much higher rates (0.3 to 3 m or 1 to 10 feet per week)
than with low-rate or irrigation-type systems where
only about 2 to 8 cm (1 to 3 inches) per week are
applied. High-rate systems require relatively
permeable soil, such as sandy loams to medium sands.
The transmissibility of the underlying aquifer should
also be sufficiently high to conduct the water laterally
away from the infiltration area without undue water-
table rises.
An obvious advantage of high-rate systems is the
low land requirement, which is only 1 to 10% of that
for low-rate systems. Because of this, the land normal-
ly is not used for growing crops and its primary func-
tion is to receive and renovate wastewater. The
effluent is usually applied with basins or furrows.
Application by sprinklers requires additional pump-
ing. Also, the frequent, intermittent application (once
every sprinkler revolution) obtained with rotating
sprinklers may not be desirable for stimulating
denitrification in the soil.
Another advantage of high-rate systems is that the
infiltration rates are much higher than the (potential)
evapotranspiration rate. Thus, the salt content of the
renovated water is only slightly higher than that of the
original wastewater. This is of importance in warm,
arid regions where the main purpose of land treatment
is to produce renovated water for unrestricted irriga-
tion, primary-contact recreation, and industrial or
other purposes. For example, if the evapotranspiration
rate is 1.8 m (6 ft) per year and the wastewater
application is 3.6 m (12 ft) per year, the salt concen-
tration of the renovated water will be twice that of the
wastewater. However, if 60 m (200 ft) of wastewater
are applied per year, the salt concentration of the
HYDRAULIC
A key soil factor in designing a high-rate land treat-
ment system is the final infiltration rate, which can be
measured with large cylinder infiltrometers. The final
infiltration rate obtained in this manner will be
reasonably accurate if the soil is uniform to great
depth or if there is a restricting layer at or near the
surface. If continuous restricting layers occur in the
zone above the water table at depths of about 10 cm (4
in.) or more, cylinder infiltrometers may seriously
renovated water will only be 3% more than that of the
wastewater (assuming uniform application over the
year and neglecting rainfall, precipitation or dissolu-
tion of salt in the soil, and other factors which have a
minor effect on the salt balance).
Because of the high hydraulic loading rates in high-
rate systems, the amounts of nitrogen, phosphorus,
and other elements entering the ground with the
wastewater are much higher than a crop could
remove. Thus, special management techniques are
required to stimulate denitrification of nitrate and im-
mobilization of phosphate in the soil to yield
renovated water of acceptable quality. High hydraulic
loading rates still yield complete removal of the
biochemical oxygen demand, suspended solids, and
the micro-organisms, at least for secondary effluent
that is applied to soils that are not too coarse and have
no cracks or other large pores.
While the quality of the renovated water is much
better than that of the original wastewater, it may not
be as good as that of the native groundwater. Thus, it
may be desirable to restrict the spread of renovated
water into the groundwater basin. This can be ac-
complished by selecting the site for the infiltration
system so that the renovated water naturally drains
into surface water. Where this is not possible, wells or
drains can be installed to artificially remove the
renovated water from the aquifer. The renovated
water can then be discharged into surface water or it
can be reused.
More detailed discussions of the various aspects of
high-rate land treatment systems for secondary
sewage effluent and other wastewater are presented in
the following sections. The paper concludes with a few
general remarks, including economic aspects and the
selection of land treatment as a solution to a
wastewater management problem.
LOADING RATE
overestimate the final infiltration rate. In that case, the
final infiltration rate can be more accurately
calculated from measurements of the vertical
hydraulic conductivity of the individual soil layers.
The long-term hydraulic loading rate for
wastewater is much less than the final infiltration rate
for clear water because (1) suspended solids and
biological activity clog the surface of the soil, and (2)
infiltration periods must be alternated with drying
85
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(resting) periods to aerate the soil and to allow the
clogging material on the surface to dry and decompose
for infiltration recovery.
The optimum application schedule must be deter-
mined for each site, since it depends on the soil and
climatic conditions as well as on the characteristics of
the wastewater. The schedule giving the highest
hydraulic loading rate may not yield the highest quali-
ty renovated water. Thus, there may be a trade off
between quantity and quality of renovated water ob-
tained. Application schedules may range from 8 hours
infiltration and 16 hours drying to infiltration and dry-
ing periods of several weeks each.
At the Flushing Meadows Project near Phoenix,
Arizona (Bouwer et al.1), optimum flooding periods
are 10 to 14 days and drying periods range from about
10 days in the summer to 20 days in the winter. The
final infiltration rate for clear water at the Flushing
Meadows Project is about 1.2 m (4 ft) per day. During
flooding, the average infiltration rate for secondary
sewage effluent is about 0.6 m (2 ft) per day. Since the
basins are flooded only about one-half the time, the
average long-term hydraulic loading rate is about 0.3
m (1 ft) per day, or one-fourth the final infiltration
rate for clear water. Lower ratios of hydraulic loading
to final infiltration rate may occur in temperate or
humid regions where longer drying periods may be
needed for infiltration recovery. The ratio also is
affected by the quality of the effluent. For example, the
suspended solids content of the effluent should be well
below 20 mg/liter to avoid serious clogging problems
(Rice2). Also, the higher the BOD, the more clogging
can be expected from biological activity.
QUALITY IMPROVEMENT
Nitrogen
Assuming a total nitrogen content of 25 mg/liter in
the effluent, 25,000 kg of nitrogen enter the soil per ha
with every 100 m of effluent applied (20,400 pounds of
N per acre with every 300 ft of effluent). This is much
more than the 50-600 kg/ha or pounds/acre that can
be removed by crop uptake. To remove more nitrogen,
denitrification in the soil must be stimulated. This is
achieved by managing the system to bring nitrate and
organic carbon together in the soil under anaerobic
conditions.
For the Flushing Meadows Project, denitrification
was maximum if flooding periods were about 10 days
and drying periods about 2 weeks. With this schedule,
oxygen in the soil was soon depleted during flooding
so that nitrogen, which was mostly in the ammonium
form in the secondary effluent, was adsorbed to the
clay and organic matter in the soil. Flooding was
stopped before the cation exchange complex was
saturated with ammonium. Oxygen then entered the
soil, causing aerobic conditions and permitting
nitrification of the adsorbed ammonium. Drying
periods must be sufficiently long to insure that all
nitrogen that was adsorbed as ammonium in the soil
during flooding will be converted to nitrate during
drying (Lance et al.3). Some of the nitrate thus formed
was denitrified in micro-anaerobic environments in
the otherwise aerobic upper few feet of the soil
(Gilbert et al.4). The remaining nitrate then was
leached out when flooding was resumed, causing a
nitrate peak in the renovated water (Bouwer et al.5).
Some denitrification probably also occurred as the
nitrate mixed with the newly infiltrated sewage
effluent while it was leached out. If the newly applied
sewage effluent entered the soil at high infiltration
rates (due to a depth of flooding of about 0.3 m (1 ft)
in the basins, for example), the nitrate was leached out
rather rapidly. Thus, there,was not much time for
denitrification and the total nitrogen removal was only
about 30%. If, however, the newly applied effluent was
allowed to enter the soil at a lower infiltration rate (by
reducing the depth of flooding in the basin to a few in-
ches) the nitrates were not leached out as rapidly and
spent more time in the microbiologically active upper
portion of the soil while mixing with the effluent. This
increased denitrification, which reduced the nitrate
peaks and yielded total-N removals of as much as 80%.
Lance et al.6 reported an exponential increase in
nitrogen removal with decreasing hydraulic loading
rate.
The flooding schedule and desired infiltration rates
for maximizing denitrification depend on the cation
exchange capacity of the soil, the ammonium ex-
change percentage, the nitrogen content of the
wastewater, the oxygen diffusion rate into the soil dur-
ing drying, the temperature, and other factors. Thus,
the optimum schedule for denitrification must be
developed for each particular system. While it is possi-
ble to estimate this schedule from theory, field testing
different schedules will usually be needed because of
the numerous factors involved.
Essentially no nitrogen was removed at the Flushing
Meadows Project if short, frequent flooding periods
(about 2 days flooding alternated with 5- to 10-day
drying periods) were used. Apparently, the soil profile
was predominantly aerobic with this schedule, and
effluent N was essentially completely converted to
nitrate. A similar situation can be expected when the
effluent is applied with rotating sprinklers (Smith7).
On rapidly draining soil, enough oxygen may enter
the soil in the short time between sprinkler revolutions
to maintain aerobic conditions, regardless of the
length of the application period. Also, no nitrogen will
be removed if the flooding periods are excessively long.
The resulting lack of oxygen in the soil will prevent
nitrate formation. The cation exchange complex will
then become saturated with ammonium, allowing am-
monium to pass through and remain in the renovated
water.
86
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Phosphorus
Assuming a phosphorus content of 10 mg/liter in
secondary sewage effluent, 10,000 kg of P would enter
the soil per ha for every 100 m of effluent
applied (2,720 pounds per acre per 100 ft effluent).
Compared with this amount, the uptake of P by plants
is negligible. Thus, the only mechanism for removing
P from the effluent water, as it moves downward
through the soil, is precipitation of P. Phosphate may
be adsorbed first and then revert to insoluble com-
pounds. This reversion occurred during drying
periods due to reaction between adsorbed phosphate
and iron and aluminum oxides released in the soil by
weathering (Beek and de Haan8). Because adsorbed
phosphate can gradually change to insoluble forms,
many soils can store more P than indicated by quick
adsorption tests.
Other insoluble P compounds are complex calcium
magnesium phosphates, such as apatites, and
magnesium ammonium phosphate. Apatites are
formed in the soil if the pH is on the alkaline side and
if sufficient calcium and magnesium are present in the
effluent or in the soil. Underground travel distances
for the renovated water of at least 100 m (several hun-
dred feet) may be necessary to obtain P-removals of
90% or more (Bouwer et al.5). Under certain soil con-
ditions, for example relatively pure sand and a pH
below 7, phosphate may be more mobile. Then,
phosphate could be removed prior to infiltration by
adding lime, alum, iron chloride, or other precipitant
to the effluent.
Minor Elements
Metals; boron, fluorine, and other elements present
in small concentrations in the wastewater may ac-
cumulate in the soil or remain in the renovated water,
depending on the element and soil conditions. At the
Flushing Meadows Project, copper, zinc, and fluoride
accumulated in the soil, but cadmium, lead, and
boron occurred in approximately the same concentra-
tion in the renovated water as in the secondary effluent
(Bouwer et al.5). About one-half of the mercury
remained in the soil. Different results may be obtained
with other soils. For example, soils containing clay or
aluminum and iron oxides will immobilize more boron
than sandy soils. Large, stable organic molecules may
act as chelating agents, thus increasing the mobility of
metals in the soil and in the aquifer.
Since most of the metals in sewage end up in the
sludge, the metal concentrations in the effluent are
usually quite low and below maximum limits
suggested for drinking water. Excessive concentrations
of minor elements in sewage effluent may be caused by
industrial discharges or by the use of certain
household products (boron) and can best be con-
trolled at the source.
Organic Carbon
The BOD of the renovated sewage water from high-
rate land treatment systems is essentially zero.
However, like most other tertiary treatment processes,
some organic carbon tends to remain in the renovated
water. The concentration of this refractory organic
carbon in the renovated water averaged about 4
mg/liter for the Flushing Meadows Project (Bouwer et
al.5). Some of this carbon may be due to lignin or
humus-like compounds (humic or fulvic acids). More
work is needed on identifying the refractory organics,
however. Renovated water is guilty until proven inno-
cent, and as long as unidentified organic carbon is
known to be present, an uncertainty remains regard-
ing use of this water for drinking or domestic pur-
poses.
Bacteria and Viruses
Evidence is accumulating that sufficient distance of
movement through relatively fine soil without large
pores or other short-circuiting passages effectively
removes all micro-organisms. At the Flushing
Meadows Project, fecal coliforms were reduced from
about 106 to generally less than 200 per 100 ml after 9
m (30 ft) of downward movement. Additional lateral
travel further reduced the coliform density to generally
less than 10 per 100 ml after 30 m (100 ft) and to zero
after 90 m (300 ft) (Bouwer et al.5).
A program of concentrating large samples (several
hundred liters) of renovated water for virus assay was
begun at the Flushing Meadows Project in January
1974 in cooperation with the Virology and
Epidemiology Department of Baylor College of
Medicine, Houston Texas. So far, virus has not been
detected in any of the renovated water samples, which
were collected bimonthly. A more detailed report will
be prepared by the investigators directly involved.
CONTROL OF UNDERGROUND FLOW
Undesirable spread of renovated water into the
groundwater basin can be avoided by locating the in-
filtration facilities so that renovated water either
drains naturally into surface water, or is intercepted
with horizontal drains if the aquifer is shallow and
with wells if the aquifer is deep. The systems must be
designed so that renovated water has had sufficient
underground detention time and has moved a suf-
ficient distance underground to be of suitable quality
when it leaves the aquifer. The proper time and dis-
tance needed depend on the quality of the effluent, the
desired quality of the renovated water, the application
rate, and the soil and aquifer materials. Generally,
movement through about 100 m (several hundred feet)
of granular soil and aquifer material with no
macropores, cracks, fractures, or other large openings,
and an underground detention time of about a month
may be sufficient to yield "safe and polished"
renovated water. Most of the quality improvement,
however, takes place in the first meter (3 feet) of the
soil profile, especially when biochemical reactions are
involved (Bouwer et al.5, Gilbert et al.4).
There are different opinions regarding the optimum
87
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depth of the groundwater table. While some persons
advocate depths of at least 3 m (10 ft), shallower water
tables may not be objectionable. If infiltration periods
longer than 2 or 3 days are employed, the oxygen in
the soil will be essentially depleted. Thus, from an
aeration standpoint, high water tables below rapid in-
filtration systems are of no concern, except for the in-
itial flooding stages. Water table rises so high that
they restrict the infiltration rate should be avoided,
however. Since most of the head due to water depth in
infiltration basins is dissipated because of surface
clogging within the first few cm (1 or 2 in.) of soil, the
water table generally will not affect the infiltration
rate until it reaches essentially the surface of the soil.
Thus, water table rises to within 15 cm (6 in.) of the
soil surface can usually be tolerated during flooding.
However, after infiltration is stopped to start a drying
(resting) period, a rapid fall of the water table is de-
sirable to quickly aerate the soil. Since the oxygen dif-
fusion rate slows considerably at depths of about 1 m
(3 ft), depending on the soil and on the soil water con-
tent after drainage (Lance et al.3), a water table depth
of about 1.5 m (5 ft) during drying seems adequate.
Deeper water tables would not materially increase the
depth of the aerobic zone during drying.
Natural Drainage into Surface Water
When renovated water is allowed to drain into sur-
face water (Figure 1), care should be taken that the
aquifer can transmit the flow of renovated water
without undue water table rises below the infiltration
areas. This can be checked with the approximate
equation
WI = KDH/L (1)
where W = width of infiltration area (m)
I = hydraulic loading rate or average in-
filtration rate for the infiltration system
(m/day)
K = hydraulic conductivity of aquifer
(m/day)
D = average thickness of zone below water
table perpendicular to flow direction (m)
H = elevation difference between water level
in stream or lake and maximum allow-
able water table level below infiltration
area (m), and
L = distance of lateral flow' (m).
If there is already a water table in the system and
natural drainage of groundwater to the surface water
already takes place, the magnitude of the drainage
flow can be calculated by substituting the "natural"
values of D and H in the right half of equation (1). The
resulting flow rate is then added to WI when applying
equation (1) to the effluent-infiltration system (see
"Example").
Equation (1) shows that the product, WI, is the im-
portant parameter of the infiltration system. Where
underground flow is restricting WI, high values of I
can still be used if W is taken proportionally smaller.
This results in long, narrow infiltration areas normal
to the slope.
WATER
TABLE
H
IMPERMEABLE
LAYER
FIGURE 1. NATURAL DRAINAGE OF RENOVATED WATER INTO SURFACE WATER.
88
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Example —
Sewage effluent is to be applied to an "infiltration
strip," which parallels a stream at a distance of 200 m
and is 30 m above the water level in the stream. The
subsoil consists of fine sand with a K-value of 5 m/day.
Impermeable material occurs at a depth of 20 m.
Groundwater occurs for most of the year at a depth of
6 m below the proposed infiltration strip, and it drains
naturally to the stream. The infiltration rate of the
effluent will be 0.2 m/day. What will be the maximum
width of the infiltration area if the water table should
not come closer than 0.5 m to the surface of the soil?
For the natural drainage flow, we have D = 20 - 6
= 14m and H = 30 - 6 = 24m. Thus the drainage flow
can be calculated with equation (1) as 5 x 14 x 24/200
= 8.4m3/day per in length of stream. During effluent
infiltration, D = 20 - 0.5 = 19.5 m and H = 30 - 0.5
=29.5 m. Thus we have
8.4 + WI = 5 x 19.5 x 29.5/200
which gives WI = 5.98 m3/day per m length of stream
or infiltration area. Since I = 0.2 m per day, the max-
imum width of the infiltration area is 29.9 m, or just
about 100 ft.
Interception by Horizontal Drains
To allow proper time and distance of underground
travel, horizontal drains for removing renovated water
from a shallow aquifer should be placed a certain
distance from the area where the wastewater enters
the soil (Figure 2). The height, Hc, of the water
table below the outer edge of the infiltration area can
be calculated with the equation (Bouwer9)
Hc2 =
IW(W + 2L)/K
(2)
where I is the infiltration rate, K the hydraulic con-
ductivity of the soil, and the other parameters are as
shown in Figure 2.
To design a given system, a certain location for the
drain is selected and Hc is calculated with equation
(2). If this does not yield the desired height of the
water table below the infiltration area, the depth of
the drain and/or some of the other variables (L, W,
and I) are changed until a satisfactory value of Hc is
obtained. Sometimes, an L-value less than the most
-IMPERMEABLE LAYER
FIGURE 2. COLLECTION OF RENOVATED
WATER BY DRAIN.
desirable distance of underground travel may have to
be accepted to obtain a workable system.
A similar calculation can be made if the renovated
water is to be intercepted with a trench or open
ditch. An example of a system of parallel infiltration
basins and drains with drains closed below flooded
areas to prevent short-circuiting was presented by
Bouwer9. If drains are located midway between in-
filtration areas, essentially no native groundwater
will enter the drains and only renovated water will
be collected.
Example —
Renovated water is to be collected by horizontal
drains which will be installed on both sides and at a
distance of 50 m from a long infiltration basins. The
drains will be at a depth of 2 m and impermeable clay
occurs at 8 m depth. The soil is dune sand with K =
10 m/day. Experiments have shown that soil clogging
will occur in the basin and that the infiltration rate
will be about 0.15 m/day. What is the maximum
width of the basin if the water table should be kept at
least 0.1 m below the basin bottom?
Taking the symbols from Figure 2, we have:
I = 0.15 m/day,
K = 10 m/day,
Hc = 7.9 m,
Hd = 6 m, and
L = 50 m.
Substituting these values into equation (2) gives W
= 15.3 m. Since the drains are on both sides of the
basin, Figure 2 represents only one-half of the system.
Thus, the maximum width of the basin is 2 x 15.3 =
30.6 m.
If, for the same conditions as above, the drain is to
be located midway between two parallel infiltration
basins which are 10m wide and 100 m apart, and if
the natural water table outside the basins is at a
depth of 0.8 m and not to be affected by the infil-
tration and drainage system, what should be the depth
of the drain?
We now have:
I = 0.15 m/day,
K = 10 m/day,
Hc = 7.2 m,
L = 50 m, and
W = 10 m.
Substituting these values into equation (2) gives
Hj = 5.94 m, so that the depth of the drain midway
between the basins should be 8 - 5.94 = 2.06 m.
Interception by Wells
Renovated water can be completely intercepted by
wells if the wells are located on a line midway be-
tween two parallel infiltration areas (Figure 3). If the
system is managed so that the water table below the
outer edges of the infiltration areas (AB) remains at
the same level as the water table in the aquifer adja-
89
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,,WELL
*////
FIGURE 3. PLAN (TOP) AND CROSS-SECTION
(BOTTOM) OF TWO PARALLEL INFILTRA-
TION STRIPS WITH WELLS MIDWAY BE-
TWEEN STRIPS FOR PUMPING RENOVATED
WATER.
cent to the system, there is no hydraulic gradient to
or from the wastewater renovation system and all
water that has infiltrated as sewage effluent in the
basins will be pumped as renovated water from the
wells between the infiltration areas. To be safe, how-
ever, the water table below the outer edges of the
infiltration area may be kept slightly below that in
the adjacent aquifer. This will cause a slight gradient
towards the wastewater renovation system, making it
impossible for renovated water to move out into the
aquifer.
The shape of the water table in a system like Figure
3 can be calculated with dimensionless graphs devel-
oped with an electrical analog (Bouwer10). One of
these graphs shows that if L/S < 0.5 (see Figure 3
for symbols), the water table at D will be lower than
at C because C is farther away from the wells. How-
ever, if L/S > 0.5, the water table at C will be
essentially at the same level as at D. The same is true
for the water table at A and B. The water table drop
from AB to CD can be calculated with the equation.
Hi = IW2/2Te
(3)
which is based on the assumption of horizontal flow
(Bouwer10). In this equation, Hi is the water table
drop from AB to CD, I is the average infiltration rate
in the infiltration area (including any dry areas), W
is the width of the infiltration strip, and Te is the
effective transmissibility of the aquifer for ground-
water recharge. The effective transmissibility is less
than the total transmissibility of the aquifer if the
aquifer is relatively deep. This is because recharge
flow systems have an upper, active zone where most
of the flow is concentrated, and a deeper passive
zone where water movement is only slight. The ef-
fective transmissibility depends on the width of the
infiltration strip in relation to the height of the
aquifer. The effective transmissibility can be evaluated
from the response of the water table to infiltration,
as was done for the Flushing Meadows Project
(Bouwer10).
The draw-down of the water table from CD to the
wells can be evaluated from a second dimensionless
graph (Figure 4) which shows the dimensionless ratio
2WSI/T w H w in relation to L/S. The symbol Hw
in this dimensionless parameter refers to the water
table drop from D to the well. The symbol Tw is the
transmissibility of the aquifer for the well-flow system.
If the wells are completely penetrating the aquifer,
the total aquifer transmissibility can be used. If the
wells are partially penetrating, the appropriate cor-
rection factor must be applied (Todd11). The other
symbols are the same as discussed for equation (3)
and shown in Figure 3.
The graph in Figure 4 is based on the theory that
the total well discharge is equal to the total infiltra-
tion rate, i.e., renovated water is pumped from the
aquifer as fast as sewage effluent enters the soil. The
use of equation (3) and Figure 4 to calculate the total
drawdown of the water table will be illustrated by
the following example.
Example —
Infiltration basins are located in two parallel strips
91.4 m (300 ft) wide and 243.8 m (800 ft) apart. Reno-
vated water is pumped from wells located 152.4 m
(500 ft) apart, midway between the strips. The aver-
age infiltration rate over the entire infiltration strip
(including dry areas) is 0.183 m/day (0.6 ft/day). The
effective transmissibility of the aquifer for the re-
charge flow system below the infiltration areas is
464.5 m2/day (5,000 ft2/day). The transmissibility
of the aquifer for the flow towards the wells is 743.2
2WSI
Vw
L/S
FIGURE 4. DIMENSIONLESS GRAPH FOR
CALCULATING WATER TABLE DROP FROM
CD TO WELL IN FIGURE 3.
90
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m2/day (8,000 ft2/day). What is the water table drop
from AB to the wells if renovated water is pumped
from the wells at the same rate as the total infiltra-
tion rate of the secondary effluent?
Solution — The calculation will be done in English
units with the end result converted in its metric equiva-
lent. We have the following quantities
W = 300 ft
L = 400 ft
S = 500 ft
I = 0.6 ft/day
Te = 5,000 ftyday
Tw = 8,000 ft2/day
For this system, L/S = 0.8, so that the water table
from A to B and C to D is essentially horizontal. Ac-
cording to equation (3), the water table drop from
AB to CD is
0.6 x 3002/2 x 5,000 = 5.4 ft
To calculate the water table drop from CD to the well,
the dimensionless parameter in Figure 4 is evaluated
as 1.3 for the L/S-value of 0.8. Thus,
2WSI/TWHW = 0.8
ECONOMIC
The economic aspects of high-rate land treatment
can not be generalized because the cost depends on
land cost, area needed, distance between treatment
plant and infiltration area, and on the interception or
collection system if the renovated water is to be reused
or otherwise taken out of the aquifer. High-rate treat-
ment on a large scale was estimated to cost about $4.3
per 1,000 m3 ($5.3 per acre-ft or $16 per million
gallons) (Bouwer5). This figure includes amortization
of capital investment, operation and maintenance
which gives
Hw = 2 x 300 x 500 x 0.6/8,000 x 0.8 = 28.1 ft.
Thus, the water table at the wells will be 28.1 + 5.4 =
33.5 ft or 10.21 m below the static water level in the
aquifer outside the system of infiltration areas and
wells. The discharge per well is
2SWI = 180,000 ftj/day = 935 gpm = 59 liters per
second.
The minimum time and distance of underground
travel for the renovated water in the system of Figure
3 will be for effluent that has infiltrated at point D.
Underground detention times can be calculated from
the equipotentials and streamlines (flow net), as
shown ip a previous paper (Bouwer10). To facilitate
these calculations, equipotentials were presented for
the flow system between CD and the well for dif-
ferent values of L/S, so that flow nets can be con-
structed and the shortest underground detention
times can be estimated.
ASPECTS
cost, and pumping the renovated water to the surface.
The cost of equivalent in-plant tertiary treatment
would be at least ten times as much.
When the land is purchased outright or is already
owned by the municipality or other agency, an impor-
tant economic aspect is increasing land value. Thus, if
a land treatment system is eventually abandoned, the
land will have considerable resale value, whereas with
in-plant tertiary treatment, buildings, pumps, pipes,
tanks, etc. depreciate and must be written off.
SELECTION AND DESIGN OF SYSTEM
The decision whether or not to use land treatment
should be based on an objective evaluation of several
alternatives. The system that is economically and en-
vironmentally the most attractive must be selected in a
rational manner. Unlike conventional or advanced
sewage treatment plants for which design criteria and
manuals are readily available, the design and opera-
tion of land treatment systems (particularly high-rate
systems) must be adapted to the local conditions of
climate, soil, and hydrogeology. This requires not only
the talents of the traditional sanitary engineer, but
also those of' the agronomist-soil scientist, the
agricultural engineer, and the groundwater specialist.
Many existing land treatment systems have been
described in the literature and the results and ex-
periences obtained are of great importance in the
design of new systems. Because of the many different
conditions that can be encountered, however, it will
always be advisable to start on a small scale, using a
pilot or experimental project, before embarking upon
any grandiose scheme, particularly in areas where
previous experience with land treatment is un-
available. It will also be desirable to continue monitor-
ing land treatment systems, so that undesirable per-
formance can be corrected before it damages native
groundwater or other natural resource.
REFERENCES
1. Bouwer, H., R. C. Rice, and E. D. Escarcega.
High-Rate Land Treatment: I. Infiltration and
Hydraulic Aspects of the Flushing Meadows Pro-
ject. J. Water Pollut. Contr. Fed. 46:835-843,
May 1974.
2. Rice, R. C. Soil Clogging During Infiltration with
Secondary Sewage Effluent. J. Water Pollut. Con-
tr. Fed. 46:708-716, April 1974.
3. Lance, J. C., F. D. Whisler, and H. Bouwer. Ox-
ygen Utilization in Soils Flooded with Sewage
91
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Water. J. Environ. Quality. 2(3):345-350, July-
September 1973.
4. Gilbert, R. G., J. B. Miller. Microbiology and
Nitrogen Transformations of a Soil Recharge
Basin Used for Wastewater Renovation. In:
Proceedings of International Conference on Land
for Waste Management, Ottawa, Canada, 1-3
October 1973, Tomlinson, J. (ed.), Ottawa,
Canada, Department of Environment and the
National Research Council of Canada, 1974. p.
87-96.
5. Bouwer, H., J. C. Lance, and M. S. Riggs. High-
Rate Land Treatment. II. Water Quality and
Economic Aspects of the Flushing Meadows Pro-
ject. J. Water Pollut. Contr. Fed. 46:844-859,
May 1974.
6. Lance, J. C., and F. D. Whisler. Nitrogen
Removal During Land Filtration of Sewage
Water. In: Proceedings of International
Conference on Land for Waste Management, Ot-
tawa, Canada, 1-3 October 1973, Tomlinson, J.
(ed.), Ottawa, Canada, Department of Environ-
ment and the National Research Council of
Canada, 1974. p. 174-185.
7. Smith, T. P. Actual Spray Field Operations. In:
Proceedings of Land Spreading Conference.
Orlando, Florida, East Central Florida Regional
Planning Council, 1970. Paper No. 8.
8. Beek, J., and F. A. M. de Haan. Phosphate
Removal by Soil in Relation to Waste Disposal.
In: Proceedings of International Conference on
Land for Waste Management, Ottawa, Canada,
1-3 October 1973, Tomlinson, J. (ed.), Ottawa,
Canada, Department of Environment and the
National Research Council of Canada, 1974. p.
77-86.
9. Bouwer, H. Design and Operation of Land Treat-
ment Systems for Minimum Contamination of
Ground Water. Groundwater. 12(3):140-147,
May-June 1974.
10. Bouwer, H. Ground Water Recharge Design for
Renovating Waste Water. J. Sanit. Eng. div.,
Amer. Soc. Civil Eng. 96(SA1): 59-74, February
1970.
11. Todd, D. K. Groundwater Hydrology. New York
and London, John Wiley and Sons, Inc., 1960.
336 p.
92
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Land Application of Treated Sewage in the Mountain State
by
Ed Light
Research Director
Campaign Clean Water
Charleston, West Virginia
Land treatment of municipal sewage is not con-
sidered feasible by the State of West Virginia. Among
the reasons cited by state officials are the unique
problems created by the topography, climate, and soil
of the Appalachian Mountains. However, ample
evidence exists which suggests that land treatment
systems will not only work but will also save tax-
payer's money.
One hundred thirty-nine communities in Califor-
nia's mountains utilize land treatment—most with a
high degree of success.1 Slopes in the treatment areas
range up to 20°.2 Most counties in West Virginia have
over one-half their land in slopes under 20°.
Therefore, experience in dealing with slopes in
California can be applicable to those areas. However,
West Virginia's five steepest counties have from 59 to
93% of their land sloping over 20°.3 The respected firm
of Bauer Engineering Incorporated of Chicago
evaluated this problem in conjunction with a proposed
sewage treatment system for the rebuilding com-
munities on Buffalo Creek, and concluded that
application of treated sewage to very steep slopes, 20°
- 40°, was feasible. Stability problems were con-
sidered, and it was found that the generally horizontal
rock layers underlying the soil would help prevent
landslide of wet soil. The application rate would have
to be limited to 1" per week.4
In regards to climate, West Virginia is subject to
periods of heavy rainfall and freezing weather. This
obstacle is overcome by providing storage facilities to
hold sewage, as is done at Penn State. At Buffalo
Creek it was estimated that 45 weeks a year would be
suitable for land treatment.
The SCS has estimated that 1/3 of the soil,
scattered throughout the Appalachians, is suitable for
land treatment.5 Soils with a heavy clay content are
good for the overland flow method of land treatment,
and better drained soils useful for spray irrigation.
Geology, soils, and groundwater patterns must be
thoroughly evaluated in choosing where and how to
use land treatment.
West Virginia is 75% forested, with much of this be-
ing of relatively low value. Irrigation with sewage in-
creases tree growth and the quality of wood fiber,
without adverse effect on wildlife.5 The Forest Service
says that there is no surface runoff from heavily
forested Appalachian slopes, so erosion should not be
a problem if application rates are not too high.
The principal economic activity in much of West
Virginia, coal mining, is not incompatible with land
treatment. In fact, the state's numerous strip mines
and coal refuse piles should be considered prime land
treatment sites. Penn State experiments show that
sewage effluent can be a valuable reclamation tool on
abandoned strip mines.6 Most of Chicago's sewage
treatment sludge is now piped to stripped areas and
this has been deemed very successful.7 With many
strip mine permits now being issued to large acreages
(100 - 1,500) and fertilizer prices skyrocketing, sewage
effluent should also become attractive for active
operations.
The U. S. Forest Service now operates two little
known land treatment facilities in West Virginia. At
Camp Horseshoe, effluent is sprayed on a flat forested
area; at Lake Sherwood, irrigation water trickles
down a hillside. Because of their proximity to
recreational streams, advanced treatment was re-
quired and land treatment was found to be the most
economical alternative. According to Forest Service
personnel, these land treatment systems are
successful.
Some 70 cities in West Virginia will be required to
go to advanced treatment. Most of these are very
small, population 500 - 5,000, so that economy of scale
for advanced treatment plants is impossible, but that
acreage needs for land treatment are not excessive.
The Buffalo Creek pilot project, proposed by the
Army Corps of Engineers but rejected by the State of
West Virginia, represented a 23% savings in total an-
nual cost over an advanced treatment plant.4 When
projected to all the West Virginia projects requiring
advanced treatment, over $1,000,000 a year in tax-
payers' money could be saved by using land applica-
tion.
The Army Corps of Engineers report concluded,
"Development of an efficient land treatment program
offers the only potential for achieving high level perfor-
mance within the forseeable future in areas such as
Buffalo Creek."4 Our organization hopes that this
view is given more serious consideration in the future
by those planning and funding West Virginia's sewage
treatment programs.
93
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REFERENCES
1. California Department of Public Health. 1971. 5. Environmental Protection Agency, Joint Conference
Sewage Disposal in Mountain Areas. on Recycling Municipal Sludges and Effluents on Land.
2. Sepp, Endel, "Disposal of Domestic Wastewater by 6. Sopper and Kardos. "Municipal Wastewater Aids
Hillside Sprays," Journal of the Environmental Revegetatioh of Strip-Mined Spoil Banks." Penn
Engineering Division , April 1973, p. 109-121. State University.
3. Stanford Research Institute, A Study of Surface Coal 7. Cornforth. "Treated Waste Water Solids Fertilize
Mining in W. Va., Vol. II, 1972. Strip-Mined Land." Coal Mining and Processing.
4. U.S. Army Corps of Engineers, Huntington March, 1972.
District, Wastewater Treatment Study, Buffalo Creek,
Oct. 1972.
94
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