United States
Environmental Protection
Agency
Great Lakes
National Program Office
230 South Dearborn Street
Chicago, Illinois 60604
EPA-905/9-91-002
GL-04-91
v>EPA
Wastewater Treatment by
Overland Flow at
Paw Paw, Michigan
Printed on Recycled Paper
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FOREWORD
The U.S. Environmental Protection Agency (USEPA) was created because of increasing
public and governmental concern about the dangers of pollution to the health and welfare
of the American people. Noxious air, foul water, and spoiled land are tragic testimony
to the deterioration of our natural environment.
The Great Lakes National Program Office (GLNPO) of the U.S. EPA was established in
Chicago, Illinois to provide specific focus on the water quality concerns of the Great
Lakes. The Section 108(a) Demonstration Grant Program of the Clean Water Act (PL 92-
500) is specific to the Great Lakes drainage basin and thus is administered by the Great
Lakes National Program Office.
Several demonstration projects within the Great Lakes drainage basin have been funded
as a result of Section 108(a). This report describes one such project supported by this
office to carry out our responsibility to improve water quality in the Great Lakes.
We hope the information and data contained herein will help planners and managers of
pollution control agencies to make better decisions in carrying forward then pollution
control responsibilities.
Director
Great Lakes National Program Office
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EPA-905/9-91-002
February 1991
WASTEWATER TREATMENT
BY OVERLAND FLOW
AT PAW PAW, MICHIGAN
By
Harry L. Bush
Village of Paw Paw, Michigan
Earl A. Myers
Lawrence J. Fleis
Williams & Works, Inc.
Grand Rapids, Michigan 49506
GRANT SOO 555 9010
Project Officer
Stephen Poloncsik
U.S. Environmental Protection Agency
Municipal Facilities Branch
230 South Dearborn Street
Chicago, Illinois 60604
Prepared for
Great Lakes National Program Office
U.S. Environmental Protection Agency
Chicago, Illinois 60604
U.S. Environmental Protection Agency
Region 5, Library (PL-12J)
77 West Jackson Boulevard, 12th Floor
Chicago, IL 60604-3590
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DISCLAIMER
This report has been reviewed by the Great Lakes National
Program Office, U.S. Environmental Protection Agency, and
approved for publication. Approval does not signify that the
contents necessarily reflect the views and policies of the U.S.
Environmental Protection Agency nor does mention of trade
names or commercial products constitute endorsement or recom-
mendation for use.
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ABSTRACT
The primary objective of this project was to evaluate the overland flow (OF) process in an
application subject to stringent nutrient effluent limitations when applying a variety of hydraulic
and organic wastewater loadings under northern climatic conditions. The main demonstration of
site was constructed to a slope of 2.5% with slope length of 175 feet and was subdivided into
three areas each of 1.66 acres (ac.). Wastewaters applied were of three types ranging in quality
from raw wastewater to well-treated aerated pond effluent from a three-pond system. Hydraulic
loadings were at 2, 3 and 4 or 3, 6 and 9 in./wk with the lower hydraulic range used for the
higher BOD wastewaters. The production OF fields were constructed to a slope of either 1.2 or
1.6%, with slope length of approximately 200 feet and included four fields totaling 46.5 acres.
OF performance treating storage pond effluent was compared for winter and summer months,
raw wastewater renovation levels were compared for several regimens of application sequences,
and renovation of mixtures of the two wastewaters was compared for below freezing and above
freezing conditions. Each of these comparisons also involved three application rates. The
primary tests involved comparison of influent and effluent concentrations for 11 parameters. To
more fully evaluate the OF process, additional tests were run; these included five heavy metals,
five additional chemical parameters, groundwater analyses, and hydrologic comparisons.
General design guidelines, including cost aspects, are discussed.
This work verified that the OF process can be used during harsh winters in northern climates and
that terrace slopes of 1.2 and 1.6% when properly constructed work as well as the generally
recommended 2 to 8% slopes. Sodded slopes have the advantages of permitting full applications
to an OF area up to one year earlier than when seeding, providing a very erosion-resistant
surface with high renovating ability at the beginning of operation, and maintaining the desired
site surface contour as developed during construction.
While highly, preapplication-treated wastewater can be satisfactorily distributed by gated pipe
and can be appropriately polished by the OF process, much management and low loading rates
are required for satisfactory application and renovation of high strength raw wastewaters. Under
the testing site conditions, 350 mg/1 of TSS and 300 mg/1 of BOD were the maximum influent
concentrations usable and still meet the 30-30 effluent requirement while maintaining relatively
low odor levels. The summertime requirement of 5 mg/1 NH3-N was easily met for all three
wastewater types; however, the 200/100 ml fecal coliform (F.Col.) count could not be met with
raw wastewater or mixtures including over 25% raw wastewater. Neither of the stringent T-P
concentrations of 1.0 mg/1 during winter or the essentially 0.5 mg/1 concentration during summer
could be met by the OF process for any wastewater type without the addition of chemicals.
This report was submitted in fulfillment of grant number SOO 555 9010 by the Village of Paw
Paw, Michigan. The work upon which this report was based was supported in part by federal
funds provided by the U.S. EPA Great Lakes National Program Office and in part by non-federal
matching funds provided by the Village of Paw Paw, Michigan. This report covers a period
form September 1, 1980 to February 28, 1986, and the demonstration project work was
completed February 28, 1986.
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TABLE OF CONTENTS
Page
Disclaimer ii
Abstract iii
Table of Contents iv
List of Tables vi
List of Figures viii
Abbreviations and Symbols ix
Acknowledgments x
Section
I INTRODUCTION 1
II CONCLUSIONS 3
m RECOMMENDATIONS 5
IV WASTEWATER TREATMENT FACILITY 6
Lagoon System 6
Flood Irrigation Areas 6
Production Overland Flow Fields 6
Demonstration Site 8
Chemical Feed System 11
V OPERATING AND MONITORING PROCEDURES 12
Lagoon System 12
Flood Irrigation Areas 12
Production Overland Flow Fields 13
Demonstration Site 13
Chemical Feed System 15
Total Treatment Plant 16
VI RESULTS AND DISCUSSION 17
Overland Flow Demonstration Site 17
Holding Pond Effluent 17
Dissolved Oxygen 21
pH 21
Biological Oxygen Demand 21
Suspended Solids 22
Phosphorus 22
Nitrogen 22
Fecal Coliform Bacteria 23
Raw Wastewater 23
Dissolved Oxygen 23
pH 26
Biological Oxygen Demand 26
Suspended Solids 26
Phosphorus 27
Nitrogen 27
Fecal Coliform Bacteria 27
IV
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Table of Contents (cont'd) Page
Mixtures of Holding Pond 27
Dissolved Oxygen 28
pH 28
Biological Oxygen Demand 28
Suspended Solids 28
Phosphorus 33
Nitrogen 33
Fecal Coliform Bacteria 33
Renovation Considerations Among Three Methods 33
Dissolved Oxygen 33
pH 34
Biological Oxygen Demand 34
Suspended Solids 34
Phosphorus 34
Nitrogen 35
Fecal Coliform Bacteria 35
Special Testing: All Three Wastewater Types 35
Heavy Metals 36
Total Dissolved Solids, Chlorides and Sodium 36
Sodium Adsorption Ratio 38
Groundwater 38
Production Overland Flow Fields 41
Hydrology 41
Quality 44
Total Treatment Plant 46
Quantities 46
Quality 49
Phosphorus 49
Dissolved Oxygen 53
Biological Oxygen Demand 53
Ammonia Nitrogen 53
pH 55
Suspended Solids 55
Fecal Coliform Bacteria 55
Facility Groundwater 55
VII COST CONSIDERATIONS 59
Construction Cost 59
Operational Cost - Overland Flow Fields 59
Operational Cost - Paw Paw Treatment System 61
SUMMARY 62
Overland Flow Area 62
Influent and Application Aspects 63
Effluent Requirements and Loading Guidelines 64
Management Aspects 65
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LIST OF TABLES
Table Page
1 Average Values and Ranges of Various Influent and Effluent Constituents
for the Demonstration Site During the December through March Months
Between December 1983 and March 1985 When Irrigating with Holding
Pond Effluent 18
2 Average Values and Ranges of Various Influent and Effluent Constituents
for the Demonstration Site During the April through October Months
Between April 1984 and April 1985 When Irrigating with Holding
Pond Effluent 19
3 Land Application Site - Average Monthly Maximum and Minimum Air
Temperatures and Precipitation Amount 20
4 Average Values and Ranges of Various Influent and Effluent Constituents
for the Demonstration Site Between June and July 31, 1985 When
Irrigating the Three Areas at Varying Times with Raw Wastewater 24
5 Average Values and Ranges of Various Influent and Effluent Constituents
for the Demonstration Site Between August 5 and September 25, 1985
When Irrigating the Three Areas Simultaneously 25
6 Maximum and Minimum Daily Air Temperatures During October,
November and December 1985 29
7 Average Values and Ranges of Various Influent and Effluent Constituents
for the Demonstration Site Between October 24 and November 18, 1985
When Irrigating with a Mixture of Raw Wastewater and Holding Pond
Effluent Under Warm Conditions 30
8 Average Values and Ranges of Various Influent and Effluent Constituents
for the Demonstration Site Between November 20 and December 16, 1985
When Irrigating with a Mixture of Raw Wastewater and Holding Pond
Effluent Under Cold Conditions 31
9 Average Soil Temperatures 1 Inch Below Soil Surface at Demonstration
Site Within Effluent Application Level Areas 32
10 Average Influent and Effluent Values of Various Constituents for the
Overland Flow Demonstration Site 37
11 Sodium Adsorption Ratio Data at Various Locations Relative to Overland
Flow Irrigation from July 17 through November 11, 1985 39
12 Concentrations at Various Constituents from Overland Flow Demonstration
Site Well Samples When Applying Wastewater Between June 1984 and
January 1986 40
VI
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List of Tables (cont'd) Page
13 Hydrologic Data from the Special Tests Run on Two Specific Production
Field Small Watersheds When Applying Holding Pond Effluent
Between September 5 and November 18, 1985 42
14 Average Values of Various Influent and Effluent Constituents for
Overland Flow Production Field Areas When Applying Effluent
from the Holding Pond During 1985 45
15 Total Treatment Plant Average Monthly Influent and Final Effluent
Flows and Total Monthly Precipitation During 1984 and 1985 47
16 Total Actual Applications of Various Wastewaters (MG/month) to
Specific Process Areas During 1984 and 1985 48
17 NPDES Limitations for Village of Paw Paw Outfall Line Discharge
to the Paw Paw River 50
18 Total Treatment Plant Average Monthly Values for Total Phosphorus
(mg/1) at Specific Locations During 1984 and 1985 51
19 Total Treatment Plant Average Monthly Values (mg/1) for Dissolved
Oxygen, Biological Oxygen Demand, and Ammonia Nitrogen of
Sewage Influent, Holding Pond Effluent, and Outfall Discharge
During 1984 and 1985 54
20 Total Treatment Plant Average Monthly Values for pH, Suspended
Solids, and Fecal Coliform of Sewage Effluent, Holding Pond
Effluent, and Outfall Discharge During 1984 and 1985 54
21 Total Treatment Plant Groundwater Monitoring Data for 1983,
1984, 1985, 1986 57
Vll
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LIST OF FIGURES
Figure Page
1 Village of Paw Paw Wastewater Treatment Plant and Groundwater
Monitoring Well Locations 7
2 Treatment System Flow Schematic 9
3 Layout of Demonstration Site 10
Vlll
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ABBREVIATIONS AND SYMBOLS
ABBREVIATIONS
ac acre
BOD biological oxygen demand
DO dissolved oxygen
EPA Environmental Protection Agency
F.Col. fecal coliform
FI flood irrigation
ft foot
gpm gallons per minute
hr hour
in. inch
kg kilogram
1 liter
Ib pound
mg milligram
MG million gallons
MGD million gallons per day
SYMBOLS
Cd cadmium
Ca calcium
Cl chloride
Cu copper
°F degree Fahrenheit
Mg magnesium
Na sodium
NH3-N ammonia-nitrogen
Ni nickel
N nitrogen
ml milliliter
min minute
NPDES National Pollution Discharge
Elimination System
No. Number
O-P ortho-phosphorus
OF overland flow
SAR sodium adsorption ratio
TDS total dissolved solids
TKN total kjeldahl nitrogen
T-P total-phosphorus
TSS total suspended solids
VSS volatile suspended solids
wk week
yr year
NO3-N nitrate-nitrogen
NO2-N nitrite-nitrogen
p
Pb
SO4
Zn
%
#
<
>
phosphorus
lead
sulfate
zinc
percent
number
less than
greater than
IX
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ACKNOWLEDGMENTS
Accomplishments of the Paw Paw demonstration project have resulted from the cooperation of
many persons and agencies. The Paw Paw Superintendent of Public Works supported the idea of
converting some of the existing marginally effective flood irrigation areas into overland flow
fields with the possibility of year-round use. As this idea developed into reality, the Paw Paw
Council supported the project with money and staff as the first overland flow system in the State.
The work was begun under a federal funds grant provided by the U.S. Environmental Protection
Agency through Region V and continued with support from the EPA Great Lakes National
Program Office. Administrative, financial, and technical assistance from the EPA through
Messrs Stephen Poloncsik, Ralph Christensen, and Richard Thomas is particularly
acknowledged.
The constructive reviews of Michigan Department of Natural Resources personnel is gratefully
acknowledged. Advice and assistance of staff members with the U.S. Department of
Agricultural Agencies and of personnel with various Michigan State University Departments are
greatly appreciated.
Technical assistance and support throughout the project by Jeffrey Sutherland and Fred Timmer
of the Williams & Works consulting firm is specifically acknowledged. Also, the conscientious
efforts in data collection and tabulation throughout the project by Betty Perkis are gratefully
acknowledged.
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SECTION I
INTRODUCTION
OF wastewater treatment systems are capable of producing highly treated effluents. Overall
facility costs, especially for energy, may be much lower than for physical-chemical processes to
achieve the same degree of treatment. The OF process is used where soil permeabilities are too
low to utilize the infiltration type of land treatment. Thus, this type system may provide an
economical form of advanced wastewater treatment for small communities which have to meet
stringent discharge standards.
The effectiveness of the OF process, however, had not been demonstrated in the northern climate
of the Great Lakes Basin. The processes abilities and limitations had not been evaluated under
controlled field conditions and design guidelines had not been established. Also, the use of
pretreatment and/or post-treatment processes, in conjunction with OF, to provide the overall
most cost-effective facility had not been documented. A project was needed to evaluate these
aspects before the system could be generally recommended for northern climates.
The Village of Paw Paw, Michigan wastewater treatment facility had a significant increase in
industrial flows and loading during late 1978 and early 1979. This increase in hydraulic and
organic loading required immediate expansion of the existing lagoon and FI plant.
The inclusion of OF areas as part of Paw Paw's treatment facility expansion seemed a judicious
solution for handling the additional flows. After years of heavy use, about half of the existing FI
areas, on the heavier type soils, were operating only marginally and were not capable of handling
increased flows. However, these areas would be economical to modify to OF, could provide
adequate capacity for the increased flow if used year-round, and would permit much flexibility
in operation of the overall facility to meet NPDES limitations.
It was decided to synchronize the expansion and modification of the existing Paw Paw facility
with a demonstration project to evaluate the OF process at this location. The Village received a
Section 108 Demonstration Grant from the U.S. EPA Great Lakes National Program Office to
evaluate the OF process. Approximately 5 acres of grass-sodded demonstration site was set
apart for detailed observation and an additional nearby 46 acres of seeded-grass production OF
fields were monitored with a less intense program. A listing of the original demonstration
project objectives follows:
1. Document the treatment performance of the OF process under a variety of hydraulic and
organic loadings and with chemical addition for P removal.
2. Evaluate the effectiveness of the OF treatment process during cold weather periods and
determine the degree to which the process can be applied in a four-season climate.
3. Document the costs of wastewater treatment by OF including actual energy utilization.
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4. Determine recommended operating parameters and design guidelines for the OF
treatment process to achieve given effluent standards in northern climates.
5. Prepare a technical report of publishable quality that will make the results of this
demonstration generally available for use by others.
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SECTION H
CONCLUSIONS
1. Influent TSS concentrations from raw wastewaters of approximately 200 mg/1 were
reduced by OF treatment to <20 mg/1 while concentrations of nearly 50 mg/1 were
reduced to between 15 and 28 mg/1
2. Influent NHs-N levels from holding pond effluent of 4 to 5 mg/1 under the colder
regimen were reduced by the OF process to between 0.5 and 1.0 mg/1, while under the
summer regimen, raw wastewater influent levels of 17 mg/1 were reduced to between 1
and 2 mg/1 and mixed wastewater influent levels of 3 mg/1 were reduced to <0.1 mg/1.
3. OF process influent BOD concentrations from mixtures of holding pond and raw
wastewaters of 200 mg/1 were reduced to <20 mg/1, concentrations from raw wastewaters
of about 400 mg/1 were reduced to between 20 and 40 mg/1, whereas a 507 mg/1 mean
raw wastewater influent concentration gave average effluent concentrations of 83, 136
and 158 mg/1 for the 2, 3 and 4 in./wk areas, respectively.
4. For all wastewater hydraulic and organic loadings under all regimens, OF process
influent T-P concentrations of 3 to 6 mg/1 were reduced to between 1 and 3 mg/1;
chemical treatment was required to produce effluent concentrations of < 1.0 mg/1.
5. For OF treatment of holding pond effluent, F. Col. influent was low enough to present no
problems in meeting the final effluent of 200 counts per 100 ml. When applying raw
wastewater or mixtures of raw and holding pond wastewater, the effluent F.Col. counts
were all >60,000. Coliform reduction treatment needed to follow the OF process in Paw
Paw due to their summer effluent limitation.
6. When irrigating holding pond effluent for OF treatment at 3, 6 and 9 in./wk levels,
NPDES requirements were easily met for summer and winter regimens, except for T-P.
Actually, most parameters showed little difference in reduction due to temperature
regimen, except for ammonia and nitrate N which were appreciably lower during summer
months.
7. The wastewater of both the 2, 3 and 4 and the 3, 6 and 9 in./wk application levels wetted
essentially all of the demonstration site; careful construction and exceptionally thick
grass stands aided in the distribution process.
8. Increased hydraulic loadings caused increased percentages of the applied wastewater to
run off and usually caused decreased renovation levels; however, the rate of renovation
decrease was not nearly as great as the hydraulic loading increase.
9. The OF process proved to be a low cost operation. However, the treatment should be
done on a production basis with applications on many acres as at Paw Paw. Operational
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costs of the overland flow represent 10% of the entire operational budget since it is only
one component of many in their treatment system.
Electrical costs or energy costs are practically negligible in Paw Paw since pumping is
not required.
10. Both the seeded and the sodded grasses of tall fescue and Kentucky bluegrass mixtures
showed essentially no stress or damage during winter applications at any of the hydraulic
or organic loadings.
11. Carefully constructed slopes of 1.2 and 1.6% functioned just as well as the 2.5% slopes;
also, the grass-sodded areas functioned just as well as the grass-seeded areas and
provided less erosion and full application conditions up to 1 year quicker.
12. High strength BOD raw wastewater prevalent in Paw Paw's system throughout the year
caused some odor problems. The wastewater entering the treatment system was nearly
black or septic due to a long transmission line. Mixing holding pond effluent high in DO
with raw wastewater solved most of the odor problem.
13. Irrigation was never continuous on the demonstration OF site throughout a winter season,
though applications were made in every winter month at one time or another during the
three-year period. This, plus extensive irrigation of the production fields during the
1984-85 winter season, verified OF as a viable process during harsh northern climatic
conditions.
14. Total treatment plant NPDES limits were readily met for all parameters throughout the
testing period involving both demonstration and production OF sites, except for T-P and
F.Col.
15. Effluent F.Col. levels of 60,000 counts per 100 ml from the demonstration site were
readily reduced to 200/100 ml after application to a FI area and the drainage mixing with
other total treatment plant groundwater flows.
16. The stringent T-P discharge levels of <1.0 mg/1 in winter and essentially <0.5 mg/1 in
summer were met by using lagoon treated effluent for OF applications and then mixing
the effluent with low T-P groundwater flows prior to the final discharge.
17. Construction of the overland flow fields was accomplished on this site by sloping
previously constructed basically flat flood irrigation fields. The construction cost of
$17,000 per acre was this high due to specific site limitations and discharge permit
requirements. However, the conversion to overland flow was cost-effective for Paw Paw.
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SECTION ra
RECOMMENDATIONS
1. The OF process at Paw Paw should be further studied with treatment of partially treated
wastewater from aeration pond #1. The bad characteristics of raw waste water (such as
odors, solids handling, and plugging problems) which were encountered during this
demonstration when applying raw or mixtures of raw and holding pond wastewaters
would be eliminated. The wastewater would be more consistent and the system could be
optimized to operate with maximum efficiency, consistent removals, and standardized
day-to-day procedures on a production basis.
Saving of overall facility costs, especially electricity and labor, from the production
irrigation of 200 to 300 mg/1 BOD wastewater relative to irrigation of <20 mg/1 effluent
from the holding pond would be realized.
2. Final treatment of OF runoff by sand filtration should be evaluated for further polishing
of P, F.Col., and solids which flow over the fields after heavy rains. The sand filtration
would be much lower cost than chemical addition and again would allow the fields to be
operated on a production basis with consistent removals.
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SECTION IV
WASTEWATER TREATMENT FACILITY
The wastewater treatment facility, Figures 1 and 2, is composed of a lagoon system, several
types of land application systems and a chemical feed system. Figure 1 shows the general
locations of these systems, the type and size of treatment ponds and land treatment areas, and the
location of 12 groundwater monitoring wells. Figure 2 shows a treatment system flow schematic
and includes the location of the demonstration site and the hydrologic test areas.The present
system average annual flow is 0.6 MGD with a BOD load of 2600 Ib/day. The 1990 system
design capacity is for an average annual flow of 1.05 MGD with BOD loading of 4200 Ib/day
and capability to handle peak monthly flows of 1.7 MGD with BOD loadings of 16,000 Ib/day.
In the following sections, each treatment system is described independently so that it can easily
be coordinated with its associated data and discussion as recorded later in the report.
LAGOON SYSTEM
The lagoon system is essentially composed of three ponds, as shown in Figure 1. Aeration ponds
#1 and #2 are each 5 ac in surface area and each contain 24 MG of wastewater at an operating
depth of 15 ft. Presently the entire holding pond is 20.5 ac in size and has a holding capacity of
120 MG. The holding pond has 114 days of detention and the three-pond system has about 160
days of detention, for the 1990 design flow.
The diffused "gun type" aeration system in ponds #1 and #2 collectively can treat 6,000 Ib/day of
BOD. Three surface aerators in each pond would increase the capacity by another 10,600 Ib/day.
This would provide the combined capacity to handle the 16,000 Ib/day peak loading for the 1990
design.
The year 2000 peak loading of 17,250 Ib/day can be handled by placing an additional aerator of
1000 Ib/day capacity in the diked-off area of the holding pond. The curtain dike and aerator are
on hand but to date have not been needed, therefore, have not been installed.
FLOOD IRRIGATION AREAS
FI areas No. 1, 4 and 7 (Figure 1) contain a total of 56 ac. They have been grubbed, deep
plowed, and underdrained with the underdrain system connected to the outfall pipe for the total
treatment plant. These areas were constructed essentially flat, are maintained in grass, and are
bermed on all sides. All applied wastewater and rainfall on these areas, therefore, must infiltrate
and percolate through the soil profile.
PRODUCTION OVERLAND FLOW FIELDS
Production OF fields No. 2, 3, 5 and 6 (Figure 1) contain a total of 46.5 ac. These fields are
subdivided into areas of approximately 175 ft in length and on slopes of 1.2 or 1.6%. These OF
fields were developed from existing FI areas which had been constructed level and which
through deterioration due to heavy usage had relatively low infiltration rates and shallow water
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Fl FLOOD IRRIGATION AREA
OF OVERLAND FLOW AREA
(2) 6ROUNDWATER MONITORING WELL
FUTURE AERATION AREA WITH
USE OF A CURTAIN WALL DIKE
OPEN CHAHWEL FROM WTP OUTLET
DISCHARGE TO
FIGURE I. VILLAGE OF PAW PAW WASTEWATER TREATMENT PLANT
f GROUNDWATER MONITORING WELL LOCATIONS
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tables. Construction of low-sloped areas avoided importing fill soil and also excavating deeply
in the lower portions of the fields.
Before the areas were leveled for FI, the soils were loamy sands to loams, underlain at depths
mainly by sand and gravel, or they were loams and loamy sands having sandy clay loam and clay
loam subsoils. During the process of leveling the areas much of the undisturbed rate of
infiltration was lost, especially on the areas having clay loam subsoils. The FI areas with the
heavier subsoils have now been reshaped into OF fields and are merely disturbed soil masses,
some having reasonable infiltration rates and some having practically none.
During the modification of an FI area to an OF field the cut and fill were balanced. The soil was
merely transferred to form furrows and uniformly sloped ridges approximately 175 ft in length.
The newly shaped soil was compacted to approximate normal field density as the work
progressed. After reshaping was accomplished, fine grading and fine seedbed working were
completed.
A cultipacker drill-seeder was used in high-rate seeding of the areas in a combination of tall
fescue, Kentucky blue, and rye grass so as to achieve uniformly sloped, very thickly vegetated
areas. A mulch was added to prevent erosion and to maintain soil moisture for establishment of
the young grass before irrigation was begun. This intensive care procedure paid off in providing
OF areas with essentially no undulations; therefore, no low spots or pooled water areas during
wastewater applications. Grassed waterways conveyed all of runoff to inlets for underground
drains that conveyed the water to the total treatment plant effluent monitoring station, see Figure
2.
An irrigation system was constructed of aluminum pipe, having a gated distribution lateral at the
top of each OF slope. The schematic layout of the OF distribution system is shown in Figure 2.
One lateral valve typically controlled the flow each sub area. Figure 2 shows the sub area
"Hydrologic Area 6C2". Thus, six lateral control valves were used in each of the fields No. 2, 5,
and 6 and four valves in field No. 3.
DEMONSTRATION SITE
Three OF subareas of 1.66 ac each comprise the demonstration site, Figure 3. The areas are
level in the north-south direction of 410 ft and are on a uniform 2.5% slope in the east-west
direction of 175 ft. They were constructed on silty fine and very fine sandy soils, taking care to
remove all vegetation and dissimilar soils. The soils were applied and compacted in uniform
layers as the 2.5% slope was developed. After final grading and top soil preparation, the final
surface was left without grooves or ridges to insure good contact between sodded-grass roots and
surface soil.
The demonstration site was sodded to save time in establishing a vegetation sturdy enough to
handle the OF rates. The sod was composed of a mixture of 50% Kentucky 31 tall fescue and
50% common Kentucky bluegrass, each seeded at 60 Ib/ac. To assure quick and good root
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FUTURE AERATION AREA WITH
CURTAIN WALL DIKE
DEMONSTRATION SITE'
(SEE FIG 3)
NO. 2
HYDROLOGIC
AREA 6C2
NO. 5
HYDROLOGIC AREA 3B-I-3C
NO, 3
FIGURE 2 TREATMENT SYSTEM FLOW SCHEMATIC
DESCRIPTION AND LEGEND
O Surface inlets to drains carrying water to outfall
£ Outlets from gated pipe OF areas
X Outlets for FI areas
D Outfall flow measurement and sampling station for total
treatment plant
NOJ Nos. Ir 4, and 7 are Flood Irrigation (FI) areas
N0.6 Nos. 2, 3, 5, and 6 are Overland Flow (OF) areas
• Manholes with central valves at a, b, c, d, e, f, and g
*- Surface runoff to drain from both sides
*- Surface runoff to drain from one side
OF areas No. 2 and No. 3 have 1.6% slopes
OF areas No. 5 and No. 6 have 1.2% slopes
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AUTOMATIC INFLUENT SAMPLER
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A CONTROL VALVE ON EACH OF THREE
UNDERGROUND WASTEYVATER
SUPPLY LINE
A/W
T
UNDERGROUND CONDUIT
TO CARRY 0 F RUNOFF TO
OUTFALL
Legend
Surface Inlets
^ Sod Waterways To Flumes
Underground Conduit
• Irrigation Gated Pipe
• Wastewater Supply
Groundwater Monitoring Wells
Sampling Station and Flume
Sampling Station Air and
Weatherstation
Soil Temperature Locations
FIGURE 3= LAYOUT OF
DEMONSTRATION SITE
10
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knitting of the sod and base soil, the surface layer of the base soil was not compacted
extensively.
The demonstration site irrigation system, shown in Figure 3, was composed of 6-in. diameter
aluminum tubing. Wastewater rate to each area was controlled by a valve at the north end of the
site. At the top of each area was a 400 ft long gated lateral pipe. Lateral pipe had adjustable
gates at 2-ft spacing; however, the number of gates that were opened and the size of each
opening were adjusted to give a uniform distribution along the entire lateral.
Slightly sloped grassed waterways along the west edge of the areas conveyed the runoff from an
independent monitoring station for each area. The effluent from the OF fields is then combined
and outletted to an underground pipe network which convey it to the total treatment plant outfall
line.
CHEMICAL FEED SYSTEM
A chemical feed system provides a means of storing, metering, mixing, and transferring either
ferric chloride or aluminum sulfate (alum) to the wastewater for the precipitation of soluble P
forms. One 8,000-gallon tank provides adequate chemical storage and two manual or automatic
metering pumps provide flexibility in operation and appropriate standby capacity. A polyvinyl-
chloride interconnecting piping system with appropriate accessories provides safety and permits
application of chemicals to various wastewater distribution points. Possible feed points include
the raw wastewater force main, aeration ponds #1 and #2, the holding pond, and the irrigation
supply lines. The schematic flow diagram, Figure 2, shows manhole "c" where chemicals could
be added to wastewater for distribution on the demonstration site and manhole "d" where they
could be added to wastewater for distribution on production OF fields.
11
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SECTION V
OPERATING AND MONITORING PROCEDURES
Operational processes are described with their associated monitoring methods and schedules. As
in the facility description section, each major process is discussed independently to provide
synchronization and ease of comparisons within the total report. Under the Demonstration Site
heading is listed the chronology of operations and testing used throughout the project period to
give perspective regarding what was done, when, and under what conditions. All test procedures
associated with monitoring followed EPA approved methods; also, an EPA approved Quality
Assurance Plan was implemented.
LAGOON SYSTEM
Throughout the project period the wastewater moved through aeration ponds #1 and #2 in series
and then into the holding pond. Ponds #1 and #2 received aeration through a subsurface diffused
aeration system; additional aeration, when required, was provided by floating aerators. The
combination of diffused and mechanical aeration provided the flexibility of activating additional
units as needed thus minimizing electrical costs.
The holding pond provided flexibility for summer and winter operations. During summer,
wastewater above that which could be handled by the OF and FI systems would be stored.
During winter, with less stringent P requirements, direct discharge to the river plus the use of
land application would be used to lower the water level in the holding pond.
Routine monitoring of the lagoon system involved twice-a-week determination of pH, BOD,
TSS, VSS, T-P, NHs-N and TKN levels for the raw wastewater influent to aeration pond #1 as
well as for the effluent from each of the the three ponds. All concentration determinations for
the raw wastewater influent were from 24-hour automatically composited samples except for pH;
however, all sampling of the effluents from the ponds was by grab sample.
FLOOD IRRIGATION AREAS
These three areas totaling 56 ac were designed to be used as much as possible throughout the
year. During May through October, each area could receive a 7-hour application equal to the 3
in./wk design amount which averages 0.65 MOD. During the remainder of the year, the amount
they receive would be controlled by the following three factors. First, temperature and rainfall
conditions would determine if they can be used at all; secondly, no more than 3 in./wk would be
applied; and thirdly, the amount actually applied up to 3 in./wk would be the minimum volume
needed to keep the final plant discharge below 1 mg/1 of T-P as explained under the Total
Treatment Plant heading of Section VI.
Continuous grass was the crop maintained on the FI areas. This crop removes a large amount of
nutrients, maintains the soil's permeability at a high level, and permits wastewater applications
essentially throughout the entire year. The grass was harvested as required to keep the
vegetation in the best condition; this was usually two or three times a year.
12
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No specific sampling and analysis were done on FI effluent discharged through the underground
drainage system. Indication of the effluent produced, however, was obtained by study of the
quantity and quality of total plant effluent when only FI areas were receiving wastewater. These
indications or estimates were used in discussing T-P adjustments under the Total Treatment
Plant section.
PRODUCTION OVERLAND FLOW FIELDS
Between May 1 and October 31, approximately 46 ac of production OF fields could be irrigated
for 7 hours each week. This would be an application level of 2 in./wk or 2.52 MG/wk,
accounting for about 0.36 MOD. Thus in summer, an average of 1 MGD could be irrigated on
the total OF and FI acreage. After November 1, the OF fields are irrigated only if the holding
pond level needs to be lowered.
The OF fields were maintained in high density stands of grass which helped screen out solids,
used large amounts of nutrients, and provided a matrix for the biological slime layer necessary
for high levels of renovation. The thick grass also slowed down the water movement, causing
more uniform wetting of the field with wastewater aiding the P removal process. The grass was
harvested three or four times a year using equipment mounted on tires having low pressures to
prevent the making of ruts.
Routine monitoring of the production OF system when applying wastewater was once-a-week
determinations of TSS, VSS, BOD, O-P, T-P, TKN, NH3-N, NOs-N, DO, pH, F.Col., and
temperature of influents and effluents. Concentrations for all parameters of the influents and the
effluents were from grab samples.
DEMONSTRATION SITE
Wastewater applications were made to the demonstration site using holding pond effluent, raw
wastewater, or mixtures of the two. A sketch indicating the layout of the site and the locations of
the equipment and instrumentation involved is shown in Figure 3. Areas A, B and (j received 3,
6 and 9 in./wk, respectively, of holding pond effluent, and 2, 3, and 4 in./wk applications of raw
wastewater and of the mixtures of the two wastewaters. Each area was irrigated by separate
gated-pipe line and each line was controlled by a valve. Each line also contained a flow meter
during the application of holding pond effluent. During the addition of the other two wastewater
types, the volume was metered at the pump station and individual lines calibrated by beaker and
stop watch for appropriate rates.
Following is a chronology of operations and testing done at the demonstration site throughout
the project period to give perspective regarding what was done, when, and under what
conditions. All applications of wastewater on the demonstration side between December 12,
1983 and April 11, 1985 were with holding pond effluent. During this period the wastewater
was applied five days per week for seven hours per day and control valves were adjusted so that
approximately one-fifth of the weekly level was added each day to each of the three areas.
13
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During this period, however, there were many weeks when no wastewater was applied due to
repair of pipes that were leaking or broken, frozen wastewater in laterals or riser pipes and fields
being dried or mowed to keep vegetation in good condition.
The wastewater supply and the irrigation application systems were modified and pretested
between April 12, 1985 and June 19, 1985. Both raw wastewater and mixtures of raw and
holding pond wastewaters were checked but no actual demonstration data secured.
Raw wastewater test data were secured between June 20, 1985 and September 25, 1985. Due to
odor problems from the raw wastewater remaining in the demonstration site supply line for
extended periods between irrigations, the decision was made to drain the line when not
irrigating. Thus, between June 20 and July 31 the demonstration site was irrigated in the
following manner. Each of the three areas was irrigated twice a week with approximately one-
half of its design amount applied each time. The pump was throttled so that the rate of
application was essentially one-sixth inch per hour to any one area; therefore, the 2 in./wk area
received two 6-hr applications, the 3 in./wk area received two 9-hr applications, and the 4 in./wk
area two 12-hr applications. The supply line was drained over the weekend.
While this procedure helped repress odors due to shorter times between transmission line use, it
caused the greater problems of varying quality to the various areas and of excess labor in valve
changing and in effluent sampling of a larger number of times. In early August, the system was
modified so that all three areas between August 5 and September 25 were irrigated
simultaneously and for the same length of time. Appropriate application levels were obtained by
irrigating the areas for 20 hr/wk (approximately 7 hr each time for three days) and applying
water to the appropriate areas at approximately 0.1, 0.15, and 0.2 in./hr average rates. This
permitted reasonable work schedules, used an efficient pumping rate and provided similar
quality wastewater to each area. Transmission lines were flushed with holding pond effluent
prior to weekends of non-use.
Though odors during summer were present, their extent seemed to be at a permissible level.
This, however, was not the case during the fall season when the odors increased. It became
judicious to stop applying raw wastewater for a period. When the demonstration site was started
up again, the raw wastewater was mixed with effluent from the holding pond. Increased odors
from the raw wastewater during fall probably were due to a combination of the following:
higher levels of BOD being applied, a higher proportion of the TSS being volatile, wetter and
colder soil conditions, vegetative material left on the field from mowing, build-up of slowly
digesting material on the fields from previous months, less sunshine, and poorer climate
conditions for aerobic digestion.
All irrigation applications, therefore, of the demonstration site after September 25, 1985 were of
mixtures of raw wastewater and holding pond effluent. Since the application of wastewater
procedure used during September worked so well it was continued. Thus, this procedure of
simultaneously applying approximately 80, 120, and 160 gpm to the 2,3, and 4 in./wk areas,
respectively, was used for all applications of wastewater to the OF demonstration site during the
14
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October 24 through December 16, 1985 test period. Since it is very difficult to meter low flows
of raw wastewater, the ratios of the two wastewater types were estimated as applied to provide
reasonable odor levels and then were established more specifically by the determination of BOD
levels in each. Demonstration site applications were terminated on December 16 due to
wastewater freezing and the extra labor intensive costs associated during freezing conditions,
and also since irrigation of both the demonstration and the production OF areas the previous
winter had verified this process as a viable option under winter conditions of this region.
For all test periods, runoff from each area was determined from individual Parshall flumes. A 4
ft 5 in. long monitoring well, placed with its top at ground level, was used in each area to secure
groundwater samples. Precipitation, as well as daily maximum and minimum air temperatures,
were secured from the on-site weather station. Soil temperatures at 1 in. of depth were secured
at three locations twice a week in each plot by the use of a portable, dial-gage, probe
thermometer.
Routine monitoring of the demonstration site OF system, was three times a week determinations
of TSS, VSS, BOD, O-P, T-P, TKN, NH3-N, NO3-N, DO, pH, F. Col., and temperature of
influent and of effluents from each area. Concentrations for the first eight parameters were from
24-hr automatically composited samples, while the last four parameters were from grab samples.
Additional influent and effluent determinations from these samples included approximately
once-each-three-months levels of Co, Mg, Na, Cl, and TDS and once-each-six-months levels of
Cd, Cu, Pb, Ni, and Zn. Also, the demonstration site groundwater monitoring wells were
sampled approximately once-each-three-months and concentrations of BOD, TKN, NO3-N, T-P,
and pH were determined.
CHEMICAL FEED SYSTEM
The present wastewater treatment facility was designed with a chemical feed system to assure
that P limitations for the final discharge receiving stream could be met. The chemical feed
system was used between August 15 and November 8, 1984 to help reduce P levels in the final
discharge. More specifically, alum was added to demonstration sites and production fields to
reduce runoff concentrations from these OF systems to about 1 mg/1. The alum was injected into
the wastewater irrigation feed lines which permitted alum applications to OF fields and also
permitted applications to the FI areas without the addition of alum. The OF fields runoff volume
at the 1 mg/1 concentration, when mixed with the groundwater and water leaching from the FT
areas, produced an acceptable final discharge T-P level as discussed under the Total Treatment
Plant heading of SECTION VI.
Due to the wide variety of treatment processes used, the chemical addition system had to be
adjusted frequently so that the most economical amount of alum could be added. In 1985, the T-
P level in the raw wastewater was decreased from previous years, probably due to an industrial
modification of wastewater discharged to the municipality's system. The lower P input and the
system's existing flexibility in detention volume and treatment processes permitted facility
management to meet P discharge limitations without the addition of alum. The chemical feed
15
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system, however, is readily available for P reductions required due to future growth, to industrial
modifications, or to situations above the land treatment plant's renovating ability.
TOTAL TREATMENT PLANT
The total treatment plant operation involves the integration of all the individual processes. The
concentration levels of the effluents discharged at the outfall and to the groundwater determine if
the facility has operated satisfactorily and has met its NPDES requirements.
Routine monitoring of the final plant effluent involved the five-times-a-week determination of
TSS, VSS, T-P, BOD, NH3-N, and F.col.; plus the everyday determination of DO, pH, and
temperature. Concentrations for the first five parameters were from 24-hr automatically
composited samples, while for the last were from grab samples. In addition the total effluent
discharge was measured daily.
All groundwater monitoring wells were sampled monthly for Cl and specific conductance; also
the status water elevation was taken monthly for each well. Yearly determinations were made of
the parameters, Ca, Mg, SO4, NH3-N, NOs-N, NO2-N, T-P, and bicarbonate as required by the
NPDES regulations.
Chlorination of the facility discharge waters has not been required due to extensive holding time
in the lagoon system; therefore, no total residual chlorine tests were required.
16
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SECTION VI
RESULTS AND DISCUSSION
The results obtained throughout the project duration and the primary discussion of them are
presented under three broad areas related to the demonstration site, the production OF fields, and
the total treatment plant.
OVERLAND FLOW DEMONSTRATION SITE
Data for the demonstration site are presented under five major headings for easier discussion of
the various project objectives. The first three major headings indicate the types of wastewater
applied and are Holding Pond Effluent, Raw Wastewater and Mixtures of Holding Pond Effluent
and Raw Wastewater. Treatment performance under a variety of hydraulic and organic loadings
is discussed under each of these three headings. Effectiveness of treatment process during cold
versus warm periods is compared by two tables, each under the Holding Pond Effluent and the
Mixtures of Holding Pond Effluent and Raw Wastewater headings. Chemical additions for P
reductions are briefly considered under the Holding Pond Effluent heading. Renovation level
comparisons among the three wastewater types and application procedures, as discussed under
heading four, provide the basis for guideline considerations presented in the SUMMARY
section. Special testing aspects which relate to all three of the wastewater types are discussed
under the fifth heading.
Holding Pond Effluent
All demonstration site results when applying holding pond effluent have been condensed into
two tables. Table 1 summarizes 24 sets of results taken during the months of December through
March between December 1, 1983 and March 31, 1985, while Table 2 summarizes 30 sets of
results taken during the months of April through October between April 1, 1984 and April 30,
1985. Each major constituent is discussed under a separate heading to facilitate comparison
when these constituents are considered under other sections.
One "set" of results is a list of the values for each parameter on a specific day. Thus, each
constituent means of Table 1 is the average of 24 days of data for that constituent. The number
of times wastewater was distributed each month was determined by on-line aspects as crop
harvesting, seasonal NPDES requirements, weather conditions, and work schedules. These
uncontrollable variables due to on-line integration prevented data-taking commensurate with
research conditions or statistical analysis.
Average monthly maximum and minimum air temperatures and precipitation amount during
1984 and 1985 are listed in Table 3. Months considered cold-period and those considered warm-
period were determined from this table. December through March temperature mean lows
ranged from 8 to 27°F and mean highs ranged from 20 to 45°F, while April through October
mean lows were 38 to 59°F, and highs 56 - 84OF. During one fall the major temperature drop
17
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Table 1
oo
Constituent
DO
BOD
VSS
TSS
O-P
T-P
NH3-N
TKN
NO3-N
F. Col.
Average* Values+ and Ranges of Various Influent and Effluent Constituents
for the Demonstration Site During the December Through March Months
Between December 1983 and March 1985
When Irrigating with Holding Pond Effluent
Influent
Mean Range
8.2
7.8
7
8
15
3.24
3.60
3.79
6.80
0.07
<100
3.3-11
7.0-8.2
4-14
2-16
3-31
2.85-3.65
2.88-4.60
3.4-8.1
4.8-12.0
0.33-1.30
<10-600
Effluent from Area
Mean
11.5
7.9
5
4
5
2.14
2.31
0.54
2.4
0.67
<50
3 in./wk
Range
8.8-13.2
7.4-8.2
2-8
1-6
112
1.60-3.15
1.88-4.70
0.10-2.05
1.3-3.9
0.3-1.4
<10-50
6
Mean
11.5
7.9
5
5
7
2.06
2.42
0.52
2.8
0.58
<10
in./wk
Range
7.8-13.6
7.3-8.2
2-10
1-15
2-19
1.80-2.85
2.00-3.20
0.10-2.09
1.0-7.0
0.29-0.94
<10-40
9
Mean
11.5
7.9
5
6
10
1.98
2.45
0.78
3.0
0.68
<50
in./wk
Range
8.6-13.2
7.3-8.1
2-9
1-17
2-40
1.58-3.00
1.08-3.40
0.10-4.10
1.45-10.0
0.40-1.15
<10-440
* Averages are for 24 sets of data: 6 in December, 10 in January, 1 in February, and 7 in March. The frequency of irrigation per
month was determined by on-line conditions as explained in the text.
+ All units are in mg/1 except pH which is in standard units and F.Col. which is in counts per 100 ml.
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Table 2
Average* Values* and Ranges of Various Influent and Effluent Constituents
for the Demonstration Site During the April Through October Months
Between April 1984 and April 1985
When Irrigating with Holding Pond Effluent
Effluent from Area
Influent 3 in./wk
Constituent Mean
DO 8.6
pH 8.3
BOD 10
VSS 17
TSS 32
O-P= 3.16
O-P# 1.88
_ T-P= 3.40
T-P# 2.34
NH3-N 0.93
TKN 4.22
NO3-N 1.02
F. Col.
* Averages are for 30 sets of data: 4 in April, 3 in May, 7 in June, 1 in July, 3 in August, 8 in September, and 4 in October. The
frequency of irrigation per month was determined by on-line requirements of the facility.
+ All units are in mg/1 except pH which is in standard units and F.Col. which is in counts per 100 ml.
= No alum additions for 18 sets during April through September.
* Alum additions for 12 sets during August through October.
:nt
Range
3.7-16
7.6-9.7
4-18
3-56
3-90
2.84-3.60
1.36-2.35
3.30-4.30
1.60-2.95
0.01-5.28
2.00-11.72
0.18-2.10
5->600
Mean
7.6
8.0
5
5
5
1.82
0.58
1.92
0.85
0.09
1.62
0.19
3 in./wk
Range
4.8-10.1
7.4-8.3
3-9
2-25
2-40
0.50-2.58
0.34-0.96
0.75-2.80
0.40-2.32
0.01-0.34
0.99-3.17
<0.05-1.42
5->600
6
Mean
7.0
8.0
5
4
5
1.92
0.58
2.13
0.84
0.08
1 .42
0.18
in./wk
Range
5.0-11.1
7.3-8.3
3-9
2-25
2-31
1.10-2.80
0.28-1.00
1.60-2.90
0.38-1.40
0.01-0.16
0.70-2.63
<0.05-1.34
5->600
9
Mean
6.7
7.9
5
5
7
1.92
0.47
2.23
0.78
0.08
1.64
0.18
in./wk
Range
4.4-12.3
7.4-8.2
3-10
1-37
2-42
1.25-2.80
0.20-0.82
1.30-2.93
0.37-1.64
0.01-0.15
0.78-3.78
<0.05-104
10=>600
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Table 3
Land Application Site
Average Monthly Maximum and Minimum
Air Temperatures and Precipitation Amount
During 1984 and 1985
Temperature
Max. Min. Precipitation
Month/Year (op) (op) (in)
Jan. 1984 20 8 1.26
Feb. 39 24 1.28
Mar. 32 18 4.31
Apr. 56 38 0.69
May 65 44 4.69
June 81 58 0.09
July 83 59 3.33
Aug. 84 58 2.50
Sept. 70 48 5.98
Oct. 62 42 3.30
Nov. 46 28 2.09
Dec. 41 26 3.09
Jan. 1985 25 14 0.78
Feb. 30 15 2.22
Mar. 45 27 4.30
Apr. 62 40 2.60
May 72 47 3.48
June 75 50 1.71
July 82 58 3.15
Aug. 78 57 2.87
Sept. 74 54 1.65
Oct. 62 42 3.78
Nov. 43 33 4.89
Dec. 22 11 1.30
2-yrAvg 56 37 2.72
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occurred between October and November and during the other it occurred between November
and December, therefore, the few November data taken were not considered in either warm or
cold periods.
Evaluation of the data means from month to month and of the ranges associated with each of
these means, indicated no major difference among the data taken within either the cold period or
the warm period. It was, therefore, considered appropriate to develop one table for the colder
weather period and another table for the warmer weather period.
DISSOLVED OXYGEN
The influent DO mean for the colder months was 8.2 mg/1, while for the warmer months it was
0.4 mg/1 higher. Effluent DO concentrations for all three respective application levels, however,
were from 3.9 to 5.2 mg/1 higher during the colder months than for the warmer ones. This trend
is also true for the ranges; as in all situations, respective values are higher during the colder
months. These higher effluent DO levels during the colder months are probably due to less
biological activity which permitted the reoxygenation achieved in OF to remain high.
During the colder months, DO effluent values were appreciably higher than influent values, but
during the warmer months, they were lower. All three effluent DO mean concentrations were
11.5 mg/1, whereas in the warmer months DO values decreased with increased loading levels.
Greater biological activity due to the increased loading probably caused the decreased DO levels.
PH
Throughout this entire period and at all influent and effluent test locations, the pH values were in
the weakly to moderately alkaline range. The lowest individual pH concentration of 7.0 was an
influent value recorded during the colder months, while the highest individual pH concentration
of 9.7 was also an influent value but recorded during the warmer months. Under ideal summer
conditions, the photosynthetic activity of blue-green algae in the holding pond can increase pH
levels very rapidly and to concentrations of 10 or above.
Effluent pH mean values were either 7.9 or 8.0 while they ranged only from 7.3 to 8.3. Thus,
there were no major differences either between the colder and the warmer months or among the
three levels of applications under either temperature regimen.
BIOLOGICAL OXYGEN DEMAND
Effluent BOD mean concentrations for all three application levels and for both temperature
regimens were the same at 5 mg/1. The influent BOD means, however, also were very low being
only 7 and 10 mg/1, respectively, for the cold and the warm regimens. Since all values are so
low, no meaningful differences are indicated.
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SUSPENDED SOLIDS
The influent TSS mean for the warmer months was 32 mg/1, while for the colder months it was
only half that, or 15 mg/1. Respective effluent TSS concentrations for the three application
levels, however, were up to 3 mg/1 higher for the colder months than for the warmer ones.
Under each temperature regimen, the higher the application level the higher the concentration of
TSS in the effluent. All of these situations could have been a result of suspended algae— in
summer more algae are produced in the holding pond; under summer field conditions, a greater
percentage of the algae are attached to the vegetation and remain on the field; and under high
rates and amounts of application, algae are more readily permitted to float through to the outlet.
Influent TSS were composed of 53% volatile material for both temperature regimens. Effluent
VSS percentages of TSS ranged from 60 to 80% for the colder months and from 70 to essentially
100% for the wanner moths. For both temperature regimens, the higher the application rate and
amount, the lower the percentage of VSS.
PHOSPHORUS
The mean values of P shown in Table 1 are for 24 sets of data, while the 30 sets of P values for
Table 2 are divided into two subgroups. The one group as indicated by footnote "#" is for 12
sets of data secured while alum was added to the influent and the other for 18 sets of data is with
no additions of alum.
Reduction of T-P concentrations during the colder months ranged from 32 to 36% or from 3.6
mg/1 influent to between 2.31 and 2.45 mg/1 effluent. During the warmer months, the 3.4 mg/1
influent value was reduced 34 to 44% when no alum was added. When alum was added,
however, the 2.34 mg/1 influent level was reduced from 64 to 67% to effluent levels between
0.78 and 0.85 mg/1. All influent and effluent T-P means for non-alum applications were between
81 and 95% ortho, while for alum additions, an O-P average of 81% was decreased to effluent T-
P means containing between 64 and 66% ortho.
With no alum additions, these data show no major difference in P reductions between
applications of wastewater during winter and summer months. Under both temperature
regimens, 0.1 to 0.3 mg/1 reductions in renovation occurred with increased application levels.
Addition of alum increased renovation percentages from the 30 and 40% to the 60% level and
also lowered the effluent T-P concentrations to <1 mg/1 for all application levels. However,
these 1 to 1.5 mg/1 T-P concentration reductions were not considered worth the cost of alum,
especially since this facility has other means of more easily and economically attaining total
plant outfall P levels required.
NITROGEN
Influent TKN concentrations were reduced from 56% to 65% for the cold months and from 66 to
71% for the warmer months. For the cold months, the percentage reduction decreased as the
22
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loading rate increased, while for the warmer months there was no systematic pattern among the
application levels. All TKN discharge concentration means for both temperature regimens were
between 1.0 and 3.0 mg/1.
The influent NH3-N mean of 3.79 mg/1 for the winter months was well above the 0.93 mg/1
summer months value. This is a typical warmer temperature condition for lagoons. The 3.79
mg/1 influent concentration was reduced to between 0.52 and 0.78 mg/1 effluent during the
winter months, whereas the 0.93 mg/1 summer months influent mean was reduced to between
0.08 and 0.09 mg/1 effluent. Crop use of NH/3-N helped produce the low summertime effluent
values.
The N03-N winter months influent level of 0.67 mg/1 produced effluent means between 0.58 and
0.68 mg/1, or essentially no change. Summertime influent mean of 1.02 mg/1, however, gave
effluents of 0.18 or 0.19 mg/1. These low summer months effluent values for N03-N were
probably due to crop uptake of N in this form.
FECAL COLIFORM BACTERIA
During the winter months, influent F.Col. values averaged <100 counts per 100 ml and effluent
values were reduced to the range of <10 to <50 counts/100 ml. During the summer months,
however, influent F.Col. values of 5 to >600 counts per 100 ml were not reduced from these
levels in the 3 and the 6 in./wk application areas and were actually increased somewhat in the 9
in./wk area. This increased F.Col. count as the water moved over the treatment area was
probably due to deer, waterfowl, and/or other small mammal activity within the area.
Raw Wastewater
Raw wastewater applications were made to the demonstration site only during the warmer
months. Results from irrigating with raw wastewater, however, were separated into two tables
determined from differing application regimens, as explained in detail under the OPERATING
AND MONITORING PROCEDURES section. While these regimens applied wastewater at
different rates and lengths of time, each supplied the designated 2, 3 or 4 in./wk to the
appropriate area. Between June 20 and July 31, 1985, the areas were irrigated at varying times
throughout the day and/or night (see Table 4). Between August 5 and September 25, 1985, all
areas were irrigated simultaneously and for the same length of time (see Table 5).
DISSOLVED OXYGEN
Influent DO concentrations of the raw wastewater were low for both regimens, averaging only
1.4 and 1.8 mg/1. The DO increased between influent and effluent in every situation, with the
range of increase being from 0.7 to 3.2 mg/1. All effluent DO means ranged from 2.5 to 4.6
mg/1; and except for the varying-times regimen for the 3 in./wk area, all DO values decreased
with increasing application amounts.
23
-------
Table 4
Average* Values+ and Ranges of Various Influent and Effluent Constituents
for the Demonstration Site Between June 20 and July 31,1985
When Irrigating the Three Areas at Varying Times with Raw Wastewater
Effluent from Area
nt
Range
0.2-3.6
6.3-7.8
184-825
100-720
140-1200
0.67-3.17
3.00-11.80
1.5-20
11.1-52
-
-
Mean
3.3
7.9
83
20
26
1.23
1.90
0.3
4.2
<0.05
2 in./wk
Range
2.2-4.0
7.28.2
5-184
7-57
12-64
0.82-1.60
0.90-2.98
<0.10-1.6
2.1-7.2
all <0.05
>60,000
3
Mean
3.7
7.9
136
13
23
1.27
2.07
0.16
3.9
<0.05
in./wk
Range
1.7-5.1
7.7-9.2
26-348
5-22
5-106
0.72-1.86
0.90-3.28
<0. 10-0.68
1.3-7.0
all <0.05
>60,000
4
Mean
2.5
7.8
158
12
15
2.07
2.67
0.47
3.9
<0.05
in./wk
Range
0.8-4.8
7.5-8.0
40-300
6-22
7-32
1.14-2.70
1.90-4.06
<0.10-1.95
1.7-7.0
all <0.05
>60,000
Constituent Mean
DO 1.8
pH 6.8
BOD 507
VSS 239
TSS 346
O-P 2.18
T-P 5.88
NH3-N 10.0
TKN 26.1
NO3-N
F. Col.
* Averages are for 14 sets of data while effluent averages are for from 8 to 10 sets of data.
+ All units are in mg/1 except pH which is in standard units and F.Col. which is in counts per 100 ml.
-------
Table 5
Constituent
DO
pH
BOD
VSS
TSS
0-P
T-P
NH3-N
TKN
NO3-N
F. Col.
Average* Values* and Ranges of Various Influent and Effluent Constituents
for the Demonstration Site Between August 5 and September 25,1985
When Irrigating the Three Areas Simultaneously with Raw Wastewater
Influent
Mean Range
1.4
7.2
437
298
354
1.55
3.63
17.1
26.5
0.5-2.8
6.5-8.5
192-879
185-1120
190-1230
0.67-2.95
3.15-5.60
3.56-25.2
18.6-39.8
Effluent from Area
Mean
4.6
7.9
26
15
28
0.66
1.13
0.26
3.8
0.06
2 in./wk
Range
3.4-6.0
7.6-8.1
7-87
6-29
7-77
0.48-0.95
0.54-1.96
<0. 10-0.66
2.6-4.5
<0.05-0.18
>60,000
3
Mean
3.9
7.9
35
16
20
1.14
1.75
1.10
5.4
<0.05
in./wk
Range
2.3-6.8
7.7-8.0
14-87
5-33
8-42
0.82-1.62
1.14-3.04
<0. 10-2.90
2.4-7.3
all <0.05
>60,000
4
Mean
3.6
7.9
35
12
15
1.58
2.03
1.98
6.4
0.09
in./wk
Range
2.1-8.0
7.9-8.2
16-860
5-18
6-24
0.84-2.35
1.11-2.82
0.10-4.64
3.4-11.0
<0.05-0.14
>60,000
* Averages are for 14 sets of data while effluent averages are for from 8 to 10 sets of data.
+ All units are in mg/1 except pH which is in standard units and F.Col. which is in counts per 100 ml.
-------
Even though the effluent DO means were above the 2 mg/1 value considered satisfactory under
the NPDES permit, odors indicated DO problems within the demonstration areas. While low-
pressure, gated-pipe applications save energy, they tend to concentrate BOD loadings near the
area where the wastewater is applied and may not make the most efficient use of the entire
field's renovating ability, especially for high BOD wastewaters.
PH
Under all situations, the influent pH mean values of 6.8 or 7.2 were increased to either 7.8 or 7.9
before discharged occurred. Thus, there were no major differences between application
regimens or among application levels relative to pH.
BIOLOGICAL OXYGEN DEMAND
Under the simultaneous-irrigation-of-areas regimen, the 437 mg/1 BOD influent mean was
reduced between 94% in the 2 in./wk area and 92% in the 4 in./wk area. The 507 mg/1 BOD
influent mean of the varying-times-irrigation regimen was reduced only between 84% in the 2
in./wk area and 69% in the 4 in./wk area. Both regimens showed decreased reductions at each of
the two higher application levels. The 26 to 35 mg/1 BOD effluent averages for the simultaneous
irrigation regimen approached the 30 mg/1 requirement, while the 83 to 158 mg/1 BOD effluents
of the varying-times-irrigation regimen were well above permitted levels.
The appreciably lower reductions of the varying-times-irrigation regimen seemed to be due to
higher rates of flow across the entire field or parts of the field. Higher flow rates over the entire
field could have been due to rainfall events, not the 3.15 in. of precipitation in July. Also,
discharging all of the pump flow to one area, even with the pump throttled, produced higher flow
rates than under the simultaneous-irrigation regimen. High flow rates over parts of a field were
sometimes caused by raw wastewater plugging a number of outlets, which increased flows out of
the open gates. In addition, the influent BOD concentration for the varying-time regimen was 70
mg/1 higher than the simultaneous-irrigation regimen and perhaps could have been of a slightly
different BOD type due to differing food industry processes.
SUSPENDED SOLIDS
All effluent TSS levels for each regimen were less than the 30 mg/1 NPDES limit, ranging from
15 to 28 mg/1. Also, for each regimen the effluent TSS levels decreased as the application levels
increased. The average reductions for both regimens were nearly identical, reducing the
influents of approximately 350 mg/1 by 92% in the 2 in./wk areas, by 95% in the 3 in./wk areas,
and by 96% in the 4 in./wk areas. Influent TSS were composed of 70 to 80% volatile material
while effluent VSS percentages of TSS ranged from 50 to 80 with no systematic variation among
the application levels.
26
-------
PHOSPHORUS
O-P comprised 37 to 42% of the influent T-P while effluents ranged from 58 to 78% ortho. This
indicates a screening-out or settling of the non-ortho phase as the wastewater moved over the
irrigation areas.
Percent of T-P removed ranged from 69 to 44 with increasing levels of simultaneous-irrigation-
regimen applications and from 68 to 55 with increasing levels of application under the varying-
time-irrigation regimen, showing essentially no difference due to irrigation regimen. Effluent T-
P concentrations for both regimens, however, ranged from 1.13 to 2.67 mg/1, all well above the
preferred 0.5 mg/1 concentration.
NITROGEN
Influent TKN concentration of approximately 26 mg/1 was reduced to between 3.8 and 6.4 mg/1,
with no notable differences between irrigation regimens nor among application levels. Influent
NO3-N was not determined in the raw wastewater and effluent NO3-N was nearly always less
than 0.05 mg/1 at all application levels for both irrigation regimens.
The NH3-N influent concentration of 10.0 mg/1 was reduced by 95 to 99% to between 0.16 and
0.47 mg/1 during June and July. During August and September, the 17.1 mg/1 influent mean was
reduced 88 to 98% to between 0.26 and 1.98 mg/1. With increased application rates, there was a
reduction of renovation, indicating the inability of the grass to use all of the N at the higher
loading levels.
FECAL COLIFORM BACTERIA
All recorded F.Col. count averages for effluents from both raw wastewater regimens and for all
application levels were >60,000.
Mixtures of Holding Pond EFFLUENT AND RAW WASTEWATER
Both raw wastewater application regimens produced decreased reductions under increased
loadings; however, neither met NPDES BOD requirements and both produced unacceptable
levels of odor. Thus, it became necessary to mix holding pond effluent with the raw wastewater
to increase DO and reduce BOD. In mixing these wastewaters, the basic criterion followed was
to add the least amount of pond effluent to maintain an acceptable odor level.
Quality data for these mixtures of wastewaters are presented in two tables, differing primarily in
temperature levels existing when the wastewater applications were made as explained below.
The proportion of holding pond effluent used in the mixture each time was determined by odor
levels, and thus varied extensively. The mixtures ranged from approximately 13% of raw
wastewater to as high as 68%. The percentage of raw wastewater was approximated by
comparing BOD levels of the mixture and those of the raw wastewater while considering holding
27
-------
pond BOD negligible as explained under the OPERATING AND MONITORING
PROCEDURES section.
Between October 24 and November 18, 1985, daily minimum temperatures never dropped below
28°F and for only four nights were below 32°F (see Table 6). For this period of essentially
above freezing temperatures, eight complete sets of data were taken (see Table 7). Between
November 20 and December 16, 1985, no daily minimum temperature was above freezing, while
during 11 days, temperature never rose above freezing and for only two days reached 4(K>F. For
this period of essentially below freezing temperatures, eight sets of data were taken for all
locations, except the 2 in./wk area where seven sets were taken (see Table 8). Soil temperatures
for the first set of data were essentially all in the 40°F range, while for the second set were in the
300 p range (see Table 9).
DISSOLVED OXYGEN
The warmer regimen influent DO mean of 3.9 mg/1 was increased to between 6.8 and 9.0 mg/1,
while the colder regimen influent was increased from 5.5 mg/1 to between 9.2 and 11.6 mg/1.
For each regimen, effluent DO values decreased with increased amounts of applied wastewater.
PH
The pH concentration under the warmer regimen increased from 7.6 at influent to 7.9 or 8.0 for
all effluents, while under the colder regimen the 8.0 pH influent remained essentially at that level
for all three effluent areas. Average effluent pH values for the 2, 3 and 4 in./wk areas under the
warmer regimen were identical to those of respective areas under the colder regimen.
BIOLOGICAL OXYGEN DEMAND
During the warmer regimen, 187 mg/1 influent BOD concentrations were reduced 94 to 95% to
effluent values of 10 or 11 mg/1, while during the colder regimen, 193 mg/1 concentrations were
reduced between 95 and 97% to values from 6 to 10 mg/1. There was no systematic pattern of
reduction among the three levels of application for either regimen. These reductions indicate no
difference in renovation even though the soil temperatures under the cold regimen averaged
1QOF colder than under the warmer regimen.
SUSPENDED SOLIDS
Influent TSS concentration of 132 mg/1 was reduced to between 7 and 9 mg/1 effluents during the
warmer regimen; while during the colder regimen, 140 mg/1 influent mean was reduced to
between 6 and 8 mg/1 effluent. There was a slightly better reduction under the colder regimen
for each corresponding application level; however, there was no systematic pattern of reduction
under either regimen relative to application amounts. Influent TSS were composed of about
75% volatile material while effluent VSS percentages of TSS ranged from 56 to 88%.
28
-------
Table 6
Maximum and Minimum Daily Air Temperatures (op)
During October, November and December 1985
October November December
Maximum Minimum Maximum Minimum Maximum Minimum
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
49
61
64
65
66
66
64
56
77
66
62
54
54
64
62
59
56
61
63
70
65
68
63
53
55
56
56
38
31
26
57
55
56
52
40
51
55
43
28
28
58
50
45
40
35
48
39
30
34
45
32
36
34
38
63
55
47
44
48
56
48
52
47
36
33
51
46
50
40
42
46
56
63
40
31
33
33
32
30
40
37
36
34
34
55
43
37
40
40
42
33
28
37
28
28
33
42
37
32
35
32
36
40
24
23
32
26
24
24
31
30
29
28
32
46
18
30
31
36
29
33
32 -'
30
34
31
29
20
10
21
20
15
12
12
21
16
11
31
12
7
5
12
14
16
32
28
12
8
16
16
21
17
17
20
29
29
28
17
10
2
11
12
4
3
-1
0
6
7
28
-4
-8
2
2
8
0
28
12
29
-------
Table 7
Constituent
DO
pH
BOD
VSS
TSS
O-P
T-P
NH3-N
TKN
NO3-N
F. Col.
Average* Values* and Ranges of Various Influent and Effluent Constituents
for the Demonstration Site Between October 24 and November 18,1985
When Irrigating with a Mixture= of Raw Wastewater
and Holding Pond Effluent Under Warm* Conditions
Effluent from Area
Influent
Mean
3.9
7.6
187
99
132
1.27
3.14
3.49
10.9
-
-
Range
2.4-4.8
6.8-8.2
114-310
52-153
76-255
0.91-2.10
2.72-4.29
2.77-4.95
8.1-20.2
.
-
2 in./wk
Mean
9.0
8.0
11
6
7
0.41
0.52
<0.10
1.4
<0.05
Range
6.6-11.1
7.8-8.2
4-24
3-16
5-18
0.30-0.69
0.36-0.74
all<0.10
1.0-2.1
<0.05-0.06
>60,000
3 in./wk
Mean
8.2
8.0
10
5
9
0.51
0,64
<0.10
1.4
<0.05
Range
5.4-9.9
7.9-8.1
4-24
3-16
5-19
0.43-0.64
0.53-0.77
all<0.10
1.1-2.0
all <0.05
>60,000
4 in./wk
Mean
6.8
7.9
11
7
8
0.68
0.88
0.13
1.5
<0.05
Range
4.5-8.0
7.8-8.1
5-23
4-16
5-16
0.54-0.84
0.56-1.21
<0. 10-0. 17
0.9-1.8
all <0.05
all >60,000
* Averages are for 8 sets of data.
+ All units are in mg/1 except pH which is in standard units and F.Col. which is in counts per 100 ml.l
= The average portion of raw wastewater in the mixture during this period was 29%.
# During this period, minimum temperatures never fell below 28°F and only 4 nights were below freezing.
-------
Table 8
Constituent
DO
pH
BOD
VSS
TSS
0-P
T-P
NH3-N
TKN
NOs-N
F. Col.
Average* Values* and Ranges of Various Influent and Effluent Constituents
for the Demonstration Site Between November 20 and December 16,1985
When Irrigating with a Mixture= of Raw Wastewater
and Holding Pond Effluent Under Cold# Conditions
Influent
Mean
5.5
8.0
193
101
140
1.13
3.16
4.59
11.2
Effluent from Area
nt
Range
2.4-9.4
7.6-8.4
100-328
60-128
98-180
0.42-1.82
2.63-4.18
2.40-8.64
9.4-14.2
.
Mean
11.6
8.0
8
4
6
0.47
0.58
0.11
1.1
<0.05
2 in./wk
Range
10.0-12.2
7.8-8.2
3-19
2-8
4-9
0.39-0.52
0.51-0.64
<0. 10-0. 13
0.9-1.4
all <0.05
3
Mean
11.1
8.0
6
5
8
0.58
0.70
0.36
1.3
<0.05
in./wk
Range
9.0-12.0
7.8-8.2
3-12
4-10
4-12
0.36-0.78
0.50-0.97
<0. 10- 1.10
0.8-2.6
all <0.05
4
Mean
9.2
7.9
10
7
8
0.67
0.83
0.71
1.6
0.6
in./wk
Range
7.4-11.8
7.7-8.1
3-26
2-10
2-12
0.51-0.79
0.69-1.08
<0. 10- 1.68
1.0-2.6
<0.05-0.10
* Averages are for 8 sets of data, except for 2 in./wk which is for 7.
+ All units are in mg/1 except pH which is in standard units and F.Col. which is in counts per 100 ml.
= The average portion of raw wastewater in the mixture during this period was 43%.
# During this period, no daily minimum temperatures were above freezing and during 11 days, the maximum temperature never
rose above freezing.
-------
Table 9
Date
Average* Soil Temperatures (°F)
1 Inch Below Soil Surface at Demonstration Site
Within Effluent Application Level Areas
2 in./wk
3 in./wk
4 in./wk
10/04/85
10/10/85
10/14/85
10/21/85
10/25/85
10/28/85
11/05/85
11/08/85
11/11/85
11/15/85
11/19/85
11/22/85
11/25/85
11/29/85
12/02/85
12/06/85
12/10/85
12/13/85
12/23/85
50.0
51.8
51.8
50.0
47.3
46.4
44.1
42.8
38.8
39.5
48.2
36.3
34.2
35.6
33.2
35.1
35.3
31.6
33.6
50.0
52.7
52.7
50.0
47.3
46.4
44.3
41.9
41.0
40.1
48.2
36.5
34.7
34.3
33.6
34.3
35.1
31.1
32.5
50.0
50.9
52.7
50.4
46.4
45.9
44.1
41.4
40.5
38.8
48.2
36.3
34.3
36.5
33.2
32.4
32.9
31.1
32.4
* Values listed are average OF temperatures obtained at three different locations within each
application area.
32
-------
PHOSPHORUS
Both regimens had influent T-P mean concentrations of approximately 3.15 mg/1. T-P reduction
under the warmer regimen ranged from 72 to 83% or to between 0.52 and 0.88 mg/1 concentra-
tions, while reduction under the colder regimen ranged from 74 to 82% for 0.58 to 0.83 mg/1
concentrations. O-P comprised 36 to 40% of the influent T-P for each of the wastewaters and 77
to 83% of the effluents from each of the wastewaters. Thus, there was essentially no difference
in P reduction due to soil temperatures being slightly below or slightly above freezing.
NITROGEN
The approximately 11 mg/1 TKN influent concentration under each regimen was reduced to
between 1.0 and 1.6 mg/1 effluent for the three application areas. Effluent NOs-N concentra-
tions were nearly always below 0.05 mg/1. The 3.49 mg/1 NH influent concentration under the
warmer regimen was reduced to approximately 0.1 mg/1 for each application level, whereas
during the colder regimen, the 4.59 mg/1 influent was reduced to 0.11, 0.36 and 0.71 mg/1 levels
by the 2, 3 and 4 in./wk areas, respectively. The greater N reductions under the warmer regimen
and the lighter loadings can readily be accounted for by crop uptake of the ammonia and nitrate
forms.
FECAL COLIFORM BACTERIA
All F. Col. count averages for effluents from both mixed-wastewaters regimens and for all
application levels were above 60,000.
Renovation Considerations Among Three Methods
This section discusses renovation level differences among the various wastewater application
regimens used on the O F demonstration site. These differences provide the basis for the
guideline considerations presented under the SUMMARY section.
DISSOLVED OXYGEN
DO comparisons among the three types of wastewater used were very definitive. Increasing
loading rates produced lower DO levels for four of the six regimens; only the 3 in./wk varying-
times irrigation procedure deviated far from this trend. Effluent DO concentrations for all colder
situations were appreciably higher than their respective warmer ones. Low DO levels associated
with high BOD concentrations of both raw wastewater regimens permitted very much odor,
while the higher DO and lower BOD levels of holding pond and of the mixed wastewaters
produced little odor. DO means of all effluent from the OF demonstration site were between 2.5
and 11.6 mg/1, all above the total treatment plant minimum requirement of 2.0 mg/1.
33
-------
PH
Effluent pH variation among the three types of wastewaters used was essentially non-existent,
varying only from 7.8 to 8.0 pH mean values of influent wastewater were the lowest at 6.8 from
direct applications of raw wastewater and were the highest at 8.3 during the summer months
from the holding pond due to photosynthesis. All demonstration site effluent means for pH were
well within the total plant's outfall requirements of 6.0 to 9.0.
BIOLOGICAL OXYGEN DEMAND
Holding pond wastewater BOD concentrations of approximately 10 mg/1 were reduced to 5 mg/1,
and mixtures of holding pond and raw wastewaters of approximately 190 mg/1 were reduced to
nearly 10 mg/1. Each of these wastewater types and their reductions involved both warm and
cold conditions which indicates relatively little BOD renovating difference between the two
temperature regimens. There was no systematic pattern or reduction among the application level
for either temperature regimens applied to the demonstration site, but all effluent BOD
concentrations were well below the normal NPDES requirement for total treatment plant
discharge of 30 mg/1. The raw influent BOD means of 437 to 507 mg/1, however, were reduced
only to between 26 and 158 mg/1 effluents from the O F demonstration site. These above
permissible values were also associated with much odor.
SUSPENDED SOLIDS
The OF demonstration site did an excellent job of reducing TSS. Holding pond effluent TSS
were reduced from 15 or 32 mg/1 to between 15 and 28 mg/I; and the mixed wastewaters TSS of
approximately 140 were reduced to less than 10 mg/1. For TSS reductions, there was no major
difference between temperature regimens nor were there any specific trends among applications
levels. All demonstration site effluent means for TSS were within the total treatment plant's
NPDES maximum 30-day average of 30 mg/1.
PHOSPHORUS
In 1984, with the use of holding pond wastewater, there usually was a slightly less ortho
percentage of T-P in the effluent than in the influent. In 1985, however, with the use of raw
wastewater and of the mixed wastewaters, the ortho percentage of T-P in the effluent was
essentially twice the level it was in the influent. This could relate to an industry modification
early in 1985 which produced appreciably lower T-P concentrations in Paw Paw's wastewater
during 1985 than during 1984. As shown later in the T-P table under the Total Treatment Plant
section.
Increased loading levels gave reduced T-P renovation for each of the wastewater types and for
both regimens under each type. Essentially no difference in T-P reduction between the colder
and the warmer regimens was indicated by both tables of temperature regimen comparison data.
Average influent T-P concentrations to average effluent concentrations varied as follows:
holding pond wastewater, 3.5 mg/1 influent gave 1.9 to 2.5 mg/1 effluent; raw wastewater 4.7
34
-------
mg/1 influent gave 1.1 to 2.7 mg/1 effluent; and the mixed wastewater 3.1 mg/1 influent gave 0.5
to 0.9 mg/1 effluent.
NITROGEN
When contrasting demonstration site colder regimens against warmer ones, for most application,
of holding pond and mixed wastewaters, greater reduction of each of the three forms on N
occurred under the warmer regimens, but no systematic reductions among application levels was
evident. The greater N reductions under the warmer regimens can readily be accounted for by
crop uptake of the ammonia and nitrate forms of N.
FECAL COLIFORM BACTERIA
Fecal Coliform bacteria count comparisons among the three types of wastewaters used indicate
the following aspects. When applying holding pond wastewater, OF effluent ordinarily meets
the NPDES 30-day average maximum count of 200 per 100 ml. When applying raw wastewater,
or even mixtures of raw and holding pond wastewaters containing more than 25% raw
wastewater, the F.Col. counts per 100 ml were all >60,000. These high counts masked any
minor differences between treatment regimens, between temperature regimens, and among
application levels. These data indicate that some type F.Col. reduction treatment needs to follow
the OF process when appreciable amounts of raw wastewater are applied and when discharge
limits in the range of 200 counts per 100 ml must be met.
Special Testing; All Three Wastewater Types
Additional chemical monitoring was conducted and quality parameters determined for all three
wastewater types at various times throughout the several years of demonstration tests. This
special testing included determining concentration levels for the heavy metals Cd, Cu, Pb, Ni,
and Zn; for TDS, Na and Cl; for Ca and Mg; and for the groundwater constituents of pH, BOD,
O-P, TKN, NHs-N, and NO3-N.
Heavy metals are rarely of concern when well treated wastewaters are applied to the land
because most of these metals are concentrated in the sludge. However, since raw wastewater
and mixtures of raw and holding pond wastewaters were used on the demonstration site, these
tests were run on both influents and effluents. High amounts of Na relative to the combined
amounts of Ca and Mg can have detrimental effects on certain soils and crops. This relationship
as defined by the sodium adsorption ratio needs to be evaluated for all land application systems.
Since little renovation of Cl occurs in land systems, this parameter gives a good indication of
wastewater movement and of hydrologic aspects. Groundwater quality data for land application
systems ordinarily are taken to assure that the treatment facility is functioning as designed and
that no abnormal modification of the subsurface waters are occurring.
35
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HEAVY METALS
Influent and effluent determinations of five heavy metal concentrations were made three times
during holding pond effluent applications and once each during applications of raw wastewater
and of the mixtures of raw and holding pond wastewaters. Concentrations of all influents and
effluents for each of the three wastewater types for Cd were <0.125 mg/1 and for Cu and Pb were
<0.25 mg/1. All effluent values of Ni were <0.25 mg/1, while influent values from the holding
pond were <0.25 mg/1, for raw wastewater was <0.89 mg/1, and for the mixture of wastewaters
was 0.31 mg/1. Zn concentrations from holding pond influents averaged 0.288 mg/1 while the
effluents ranged from 0.258 to 0.442 mg/1, and for the other two wastewater types influent
concentrations of 0.18 and 0.28 mg/1 both gave all effluents of <0.125 mg/1.
Trace element and heavy metals are nutrients necessary for plant growth, but when added to soil
in excessive quantities may cause injury to crops or perhaps damage to people through the food
chain. Zn, Cu and Ni ordinarily cause major crop injury long before damage would be caused to
people through the food chain. Cd and Pb can cause damage through the food chain but these
elements added to the soil are not a hazard until they have actually entered edible parts of plants.
Soil factors affecting the toxicity of these metals include pH, organic matter, P content, and
cation exchange capacity. Relative to the previous comments and to generally accepted heavy
metal application levels, the above heavy metal values do not indicate a cause for concern. Due
to low levels of heavy metal concentrations in the wastewaters and to the small volumes of raw
sewage applied, no soil sampling nor crop tissue testing were completed for determining these
constituents.
TOTAL DISSOLVED SOLIDS, CHLORIDES AND SODIUM
Additional chemical tests were conducted on both influent and effluent of all three wastewater
types (see Table 10). These special tests occurred about once each quarter and included
determinations of TDS, Cl and Na. Since relatively little change of these parameters would be
expected in OF, analysis of these data should give some indication of field hydrology.
When applying holding pond effluent and averaging the August, January and March results, very
little difference occurred between the concentrations applied and the concentrations in the runoff
for all parameters and under each application level. These results should be expected from the
averaging of data and since several seasons of the year were included.
During the July application of raw wastewater, influent Cl of 107 mg/1 increased from 60 to
74%, influent Na of 144 mg/1 increased from 25 to 41%, and influent TDS of 1036 mg/1
increased from -12 to 18%. All effluent levels were higher in concentrations than influent levels
for all parameters and all application levels, except for the 2 in./wk area for TDS. The
differences in increased percentage levels among the three constituents indicate differences in
the soil-crop eco-sphere to use or tie-up these constituents. The highest percentage increases in
the Cl concentrations indicates essentially no crop use or soil tie-up of this element, therefore
increasing the Cl content of the unused water which moved out as interflow.
36
-------
Table 10
Average* Influent and Effluent Values of
Various Constituents for the Overland Flow Demonstration Site
Influent to Effluent from Area# (mg/1)
AH Areas
Constituent (mg/I) xin./wk yin./wk zin./wk
(when applying holding pond effluent during 1984 and 1985)
TDS 831 802 789 835
Na 214 206 207 215
Cl 226 227 238 246
* Averages are for three sets of data taken 8/9/84,1/7/85, and 3/25/85.
# x, y and z values for this subtable are 3, 6 and 9, respectively.
* * *
(when applying raw wastewater on July 17 and 18,1985))
TDS 1,036 916 1,227 1,046
Na 144 191 203 180
Cl 107 179 171 186
* Influent is average of two sets of data while effluents are all individual measurements.
# x, y and z values for this subtable are 2, 3 and 4, respectively.
* * *
(when applying a mixture+ of raw and holding pond wastewater on November 11, 1985)
TDS 1,013 519 632 699
Na 270 156 174 204
Cl 277 120 160 185
* All data are for individual measurements.
# x, y and z values for this subtable are 2, 3 and 4,, respectively.
+ The portion of raw wastewater in the mixture was approximately 26%.
37
-------
For the November application of mixed wastewaters, influent TDS of 1,013 mg/1 were reduced
from 31 to 49%; influent Na of 270 mg/1 was reduced from 24 to 42%; and influent Cl of 277
mg/1 was reduced from 33 to 57%. For all three constituents, the percentage of reduction
decreased as the amount of wastewater applied increased. Actually, the primary method of
reduction, especially for Cl, was dilution. Since there was no rain on this date, the dilution
probably came from the applied wastewater mixing with interflow from the rains of 0.83 and
0.28 inches on November 9 and 10, respectively.
SODIUM ADSORPTION RATIO
SAR data relative to OF irrigation were taken at certain locations between July 17 and
November 11, 1985, Table 11. The data were from influents for all three wastewater types and
for effluents from the three demonstration areas and one production field. This ratio of the
single valent cation Na to the double valent cations Ca and Mg predicts the occurrence of
detrimental effects to soils and crops due to excess Na and is given in Table 11.
These data indicate appreciable variation of SAR levels of influent raw wastewater, from 2.9 to
8.8, as compared to relatively uniform values for holding pond effluent, from 5.2 to 5.8. They
also indicate effluent SAR values vary directly with influent SAR levels; i.e., September 24
holding pond wastewater applications of SAR 5.7 gave production field effluent of 5.2;
September 25 raw wastewater demonstration area influent of SAR 8.8 gave effluents of SAR 7.8
to 8.5; and July 17 and 18 raw wastewater influent of 3 to 5 gave demonstration area effluents of
SAR 4.2 to 4.7.
SAR values of 5 to 10 tend to decrease a soil's infiltration rate, especially if the soil is high in
clay content. Decreased infiltration often is considered of little concern in OF systems, but can
be devastating for flood irrigation regimens. Also, where OF facilities are not truly "over" land
flow, but actually involve much interflow for removal of P, etc., high SAR levels can be very
detrimental.
GROUNDWATER
A shallow groundwater monitoring well was located in the center of each demonstration area,
Figure 3. These wells were labeled A, B and C and relate to increasing application levels,
respectively. Groundwater sampling and analyses were done on the dates shown in Table 12,
which includes one or more sets of data from each of the three types of wastewaters applied.
The wells were approximately 4 feet deep with the bottom 2 feet being screened.
The demonstration site groundwater concentration major changes of T-P, BOD and TKN from
time to time indicate a malfunction of the sampling wells. Shallow groundwater monitoring, in
modified soil situations, by the use of driven wells is not always a successful venture. Frost
action and/or modified sandy soils, in combination with the large volumes of OF plus rainfall
water, probably caused short circuiting of the water through the nearly 2 ft of soil above the top
of the well screen.
38
-------
Source
Prod. Effl
Table 11
Sodium Adsorption Ratio Data* at Various Locations
Relative to Overland Flow Irrigation from
July 17 through November 11,1985
Date
09/24
Na
204
Ca
66
* All units are in mg/1 except SAR which is a standard ratio:
Na+
Mg
30
Mg++)/2]0.5
Where Na, Ca, and Mg are expressed in milliequivalents per liter
SAR
Holding Pond
Holding Pond
Holding Pond
Raw
Raw
Raw
Mixed
2" Effl
2" Effl
2" Effl
3" Effl
3" Effl
3" Effl
4" Effl
4" Effl
4" Effl
08/19
09/16
09/24
07/17
07/18
09/25
11/11
07/18
09/25
11/11
07/17
09/25
11/11
07/18
09/25
11/11
192
212
234
170
117
388
270
180
400
156
203
400
174
171
374
204
66
63
76
63
77
88
86
75
104
52
76
124
58
76
96
72
22
23
30
20
28
36
40
21
38
23
30
44
25
30
40
44
5.2
5.8
5.7
4.8
2.9
8.8
6.0
4.7
8.5
4.5
4.6
7.8
4.8
4.2
8.1
4.7
5.2
39
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Table 12
Concentrations* at Various Constituents from
Overland Flow Demonstration Site Well* Samples
When Applying Wastewater Between June 1984 and January 1986
Well Date
A 6/01/84
8/16/84
4/03/85
5/31/85
7/19/85
9/30/85
1/22/86
B 4/03/85
5/31/85
7/19/85
9/30/85
1/22/86
C 6/01/84
8/16/84
4/03/85
5/31/85
7/19/85
9/30/85
1/22/86
pH
7.6
7.6
7.4
7.0
7.7
7.3
7.4
7.3
7.3
7.8
8.3
8.3
7.6
8.0
7.4
7.2
7.7
7.5
7.6
BOD
2
2
4
3
14
6
2
4
9
4
-
4
8
1
4
11
4
10
1
O-P
<0.08
0.05
<0.40
0.21
0.59
0.53
0.046
0.80
0.30
0.05
0.32
0.044
0.84
0.66
0.90
<0.04
0.04
0.54
0.04
TKN
1.2
1.4
1.3
1.9
1.9
4.5
1.5
0.9
3.5
1.0
-
1.5
2.3
1.6
1.2
3.2
1.3
4.5
1.7
NH3-N
-
0.51
0.69
0.36
0.45
0.44
0.48
0.28
0.29
0.22
0.37
0.28
_
0.59
0.50
1.08
0.46
1.08
-
NO3-N
<0.125
0.10
0.22
0.31
<0.05
<0.05
<0.05
0.32
0.05
<0.05
<0.05
<0.05
<0.125
0.14
0.31
0.23
0.07
0.05
<0.05
Applied
Wastewater
Pond #3
Pond #3
Pond #3
Raw
Raw
Mixture
None for
1 Month
Pond #3
Raw
Raw
Mixture
None for
1 Month
Pond #3
Pond #3
Pond #3
Raw
Raw
Mixture
None for
1 Month
* All units are in mg/1, except pH which is in standard units.
# Wells A, B and C are in application areas 2, 3 and 4 in./wk, respectively.
40
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The January 22, 1986 samples were taken a month after termination of applications to the
demonstration site. O-P values of 0.04 in each well, plus low values of BOD and TKN are
indicative of background groundwater quality. Data from demonstration site wells on other
sampling dates indicate mixtures of treated and partially treated wastewaters; however,
appropriate well data from the total facility wells are presented under the Total Treatment Plant
section.
PRODUCTION OVERLAND FLOW FIELDS
In an attempt to delineate more precisely quantity and quality, influent and effluent relationships
on production OF fields, a series of special tests were run on each of two areas that were
relatively easy to isolate. In the summer of 1985, a 90°V-notch weir plus an automatic depth
recorder were installed on each of two specific watersheds; one referred to as area 3B+3C and
the other as 6C2. These references indicate their field locations and their watershed supply valve
designations, Figure 2.
Watershed 3B+3C is V-shaped and was irrigated by two gated laterals. The 3B lateral irrigated
1.26 ac and the 3C lateral 2.53 ac for a total of 3.79 ac. Watershed 6C2 slopes from only one
side to the outlet channel, was irrigated by only one lateral, and contains 2.23 ac. Each lateral
was controlled by one valve and following each valve was a water meter for determining the
volume of wastewater applied.
The following sections on hydrology and quality discuss the results obtained from these special
tests. Also for comparison, routine production OF field results are included and demonstration
site data considered.
Hydrology
Seven hydrographs were produced by the hydrologic equipment installed in the 3B+3C area,
while eight were produced from the equipment in the 6C2 area. One week before the test runs
were made, a pre-test application was made to produce hydrologic conditions similar to those
when a 2 in./wk sequence is being followed. Data determined from the hydrographs and
additional data relative to these special tests are shown in Table 13. Due to rainfall events and
equipment malfunction, not all of the hydrographs were used, as noted at the bottom of the table.
For a 2-in. application, watershed 3B+3C should receive approximately 0.205 MG and
watershed 6C2 about 0.121 MG. As noted, however, the volume applied ranged from 0.161 to
0.309 MG on watershed 3B+3C and from 0.181 to 0.268 MG on watershed 6C2. These
variations were primarily due to the use of on-line large irrigation valves. These valves normally
operate in the completely open position and function quite well; however, these flows required
operation in the nearly closed position. After the valves were adjusted to the proper flow rate,
they would automatically "slip" a small amount over time. This slippage plus slight changes in
the hydraulic head on the valves, caused major flow differences.
41
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Table 13
Hydrologic Data* from the Special Tests
Run on Two Specific Production Field Small Watersheds
When Applying Holding Pond Effluent
Between September 5 and November 18,1985
- - Watershed - -
Items and Units 3B + 3C 6C2
Area, ac 3.79 2.23
Volume applied, MG 0.161 to 0.309 0.181 to 0.268
Volume in runoff, MG 0.081 to 0.120 0.028 to 0.103
Percentage of runoff, % 39 to 50 14 to 57
Application depth, in. 1.57 to 3.01 2.99 to 4.43
Application rate, gpm 380 to 850 422 to 564
Peak runoff rate, gpm 230 to 320 75 to 290
Percentage peak runoff, % 36 to 61 18 to 52
Base flow time, days 1 to 1.5 2 to 2.5
The data for watershed 3B + 3C was secured from the best three of seven hydrographs of
this area while the 6C2 data was secured from six hydrographs of the eight for this
watershed.
42
-------
Runoff volume is determined from the area under a hydrograph, which accounts for the
discharge rates over the weir and the lengths of time they occur. Runoff volumes ranged from
0.081 to 0.120 MG for watershed 3B+3C and from 0.28 to 0.103 MG for watershed 6C2. These
runoff volumes relative to applied volumes ranged from 39 to 50% for watershed 3B+3C and
from 14 to 57% for watershed 6C2.
Application rates were determined by dividing the volume applied by the length of application
time and ranged from 380 to 850 gpm. The peak runoff rates were determined from the
maximum depths of flow over the weirs and ranged from 75 to 320 gpm. The peak runoff rates
relative to the average rates of application ranged from 36 to 61% for watershed 3B+3C and
from 18 to 52% for watershed 6C2.
Base flow time in this report was considered the length of time between when the lateral valve
applying water to the area was closed and when water stopped running over the weir. This
included time for direct runoff over the surface and also time for interflow to dissipate. Base
flow times ranged from 1 to 1.5 days for watershed 3B+3C and from 2 to 2.5 days for watershed
6C2.
Additional hydrologic items gleaned from the hydrographs and information secured while
obtaining them include the following. Item 1 — On September 13, 1985 during a pre-test run,
0.174 MG or 2.88 in. were applied to area 6C2 at the rate of 520 gpm; and in 5 hr, 35 min, no
water reached the toe of the slope; on September 17, water was applied to area 6C2 at 564 gpm;
5 hr, 45 min were required before water began running over the V-notch and only 26% of the
0.268 MG (4.4 in.) applied ran off; however, eight days later on September 25, only 3 hr were
needed before water began to run over the weir and 57% of the 0.181 MG (3 in.) applied ran off.
Item 2 — On September 11, six days after a pre-wetting application, for watershed 3B+3C, water
began to run over the weir only 2 hr after application was begun at 600 gpm; and 3 hr, 20 min
after the beginning of application, 33% was running off. The only rainfall which occurred
during this September 10 to 25 period was a total of 0.28 inches on September 22 and 23.
These two additional items indicate infiltration, interflow, and base flow differences between the
two watersheds, as well as the effect of hydrologic differences within a watershed from time to
time. It is these types of differences plus crop and climatic effects which cause major
differences in renovation levels, especially in P removals, among watersheds.
Demonstration site hydrologic data between October 28 and November 6, 1985, during which
time only 0.26 in. of precipitation fell, indicate infiltration and runoff values typical for the three
application-level areas. During this period, percentage runoff of the 2, 3 and 4 in./wk areas were
33, 39 and 65%, respectively. These percentage runoff values are somewhat similar to those for
the production OF areas of Table 13. The actual application rates and actual inches applied on
the production and the demonstration watershed areas also were similar, even though much more
variation occurred within a watershed on the production areas. Demonstration site runoff for the
periods of September 4-6 and 17-19, 1984 indicate hydrologic conditions for the heavier
43
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application levels. During these periods, only 0.13 in. of rain fell and the runoff was 37, 96 and
87% for the 3, 6 and 9 in./wk areas, respectively.
It is interesting to note that 2, 3 and 4 in./wk application levels of 3.1 mg/1 T-P on the demonstra-
tion site between October 24 and December 16, 1985 gave effluents between 0.5 and 0.9 mg/1,
while on the production areas approximately 2 to 4 in./wk application levels of only 2.2 mg/1 T-P
gave effluents of 1.3 to 1.7 mg/1 between September 5 and November 18, 1985. These
differences could have been due to differences in the holding pond and the mixed wastewater
characteristics; they could have been due to different length of contact time of wastewater with
the soil surface due to grass thickness; they could have been due to differences in infiltration and
interflow; or they could have been due to sampling procedures, since demonstration site data
came from automatically composited samples and production data from grab samples. Produc-
tion projects usually are not designed specifically enough to consider this degree of detail.
Quality
Quality results of the production OF fields for 1985 include seven sets of data from watershed
3B+3C, eight sets from 6C2, and nine sets for samples composited from fields Nos. 2, 3, 5 and 6
(see Table 14). These data, in a general fashion, will be compared among each other, with 1984
production OF results and with demonstration site data.
The production OF concentration levels of pH, DO, BOD, TSS and VSS for 1985 follow the
same trends for each constituents as discussed under results obtained when using holding pond
effluent on the demonstration site. Effluent pH values are either 7.9 or 8.0. Colder temperature
conditions produce DO values slightly higher than warmer conditions. BOD concentration
average levels in the effluent are <10 mg/1. Effluent TSS are slightly higher under colder
temperatures than warmer ones and VSS range from about 50 to 80% of TSS. All 1984
production OF field data for these five constituents fall within the ranges listed in Table 14.
For area 3B+3C, the T-P influent concentration of 2.24 mg/1 was reduced 25% to 1.69 mg/1
effluent, while for area 6C2, the 2.18 mg/1 influent mean was reduced 41% to T.28 mg/1 effluent.
The 6C2 T-P reduction was essentially the same as the 43% average reduction for the nine
composite samples. Also, the range of T-P reductions of the production OF fields (24 to 43%)
was nearly the same as for the demonstration site when irrigating with holding pond effluent (32
to 44%). Unfortunately, all of the effluent T-P values for production and demonstration areas
during 1984 and 1985 were between 1.28 and 2.45 mg/1, well above the desired 0.5 mg/1 level,
unless alum was added.
All TKN discharge concentration means for the production fields (see Table 14) were between 1
and 3 mg/1, as they also were for the demonstration site when using the same type of wastewater
during 1984 and 1985. All production and demonstration areas gave effluent values for NH3-N
and N03-N of <0.5 mg/1 during summer and between 0.5 and 1.0 mg/1 during the colder- months,
probably indicating differences in N uptake by the grass.
44
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Table 14
Average* Values* of Various Influent and Effluent Constituents
for Overland Flow Production Field Areas+
When Applying Effluent from the Holding Pond During 1985
Area 3B + 3C
Constituents Influent Effluent
pH
DO
BOD
TSS
VSS
T-P
TKN
NH3-N
NO3-N
F.Col.
8.5
6.0
8
23
16
2.24
3.95
1.67
0.38
20±
7.9
7.9
6
5
3
1.69
1.99
0.24
0.16
280±
Area 6C2
Influent Effluent
8.5
6.1
8
23
15
2.18
3.68
1.35
0.54
20±
7.9
8.4
7
8
7
1.28
2.16
0.12
0.44
200±
7.8
9.4
20
26
13
3.58
8.06
4.74
0.95
100±
Production
Field Composite
Influent Effluent
8.0
11.3
7
14
7
2.03
2.51
0.99
0.88
200+
* Data for area 3B + 3C are averages of 7 sets of information, for area 6C2 are of 8 sets, and
for production field composites are of 9 sets.
# All units are in mg/1, except for pH which is in standard units and for F.Col. which is in
counts per 100 ml.
+ Data for the special tests on the small watershed areas 3B + 3C and 6C2 were taken between
September 5 and November 18, while the composited data from all four of the production
OF fields were taken between January 3 and May 14.
45
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F.Col. bacterial counts increased in nearly every situation as wastewater flowed across the fields.
This increase usually was higher under warmer conditions than under colder ones. Some of the
F. Col. increase was due to wildlife use of the areas.
TOTAL TREATMENT PLANT
This section discusses the Paw Paw NPDES limited parameters and the production processes
involved in meeting these required limits. The NPDES parameters included are P, DO, BOD,
NH3-N, pH, SS, and F.Col., while the treatment received involves lagoons as well as OF and FI
land application processes. This was an on-line facility and was operated to meet required
discharge limits at the most economical cost. Facility groundwater qualities are also considered.
Quantities
Average monthly influent and discharge rates for the total facility are listed in Table 15. This
table also includes the quantity related data of total monthly precipitation.
The two-year average daily influent flow was 0.56 MOD and ranged from 0.37 to 0.73 MOD
with no clear variation due to seasons of the year. Neither precipitation variations from month to
month nor from season to season indicate any noticeable effect on the average monthly inflow
rates. The month to month influent rate differences are primarily a result of industrial process
requirements.
Average daily discharge for the two-year period was 1.62 MOD and ranged form 0.97 to 2.90
MOD. This average daily discharge compared to the average daily inflow indicates
approximately 1 MOD of groundwater being discharged through the outfall line. While rainfall
events obviously affected these discharge rates, their average monthly effects were masked by
the larger volumes of wastewater applied to the OF and FI process areas and by monthly
evapotranspiration losses.
Volumes of wastewater actually applied to specific process areas are listed in Table 16. In 1984,
OF areas received 66% of the holding pond discharge, while FI areas received 34%. During
1985, however, OF areas received 17%, FI areas 23%, and 60% was discharged directly to the
outfall line. These discharge variations primarily are due to an on-line system being operated to
meet NPDES requirements in an economical manner as explained more fully in the P discussion
under the following section on total treatment plant quality.
The winter of 1985 shift to appreciably more FI than OF of production areas basically related to
economically meeting P requirements, but deserves additional comment. Under winter
conditions at Paw Paw, irrigation by OF permitted only 2 in. depths of application per value
change and produced only about 33% P removal, while under FI 3 in. depths were applied per
value change, about 90% removal was produced, and appreciably larger areas were irrigated
from a single control valve. FI, therefore, permitted more direct discharge to the outfall line with
additional savings of time and money. The low-head gated-pipe OF distribution system also
required more time for adjustment of flows for uniformity of distribution, which in winter is not
a preferred manual task.
46
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Table 15
Total Treatment Plant Average Monthly
Influent and Final Effluent Flows
and Total Monthly Precipitations
During 1984 and 1985
Month/Year
Jan. 1984
Feb.
Mar.
Apr.
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Jan. 1985
Feb.
Mar.
Apr.
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
2-yr. Avg
Plant
Influent
(MGD)
0.37
0.52
0.46
0.47
0.60
0.63
0.73
0.51
0.45
0.63
0.51
0.51
0.56
0.61
0.69
0.63
0.58
0.62
0.69
0.50
0.62
0.62
0.52
0.42
Final
Effluent
(MGD)
Meter out
1.46
1.90
1.37
1.50
2.90
1.17
1.10
1.40
1.58
1.64
1.73
1.74
1.93
2.72
2.20
1.34
1.15
1.18
0.98
0.97
1.21
2.15
2.04
Precipitation
(in.)
1.26
1.28
4.31
0.69
4.69
0.09
3.33
2.50
5.98
3.30
2.09
3.09
0.78
2.22
4.30
2.60
3.48
1.71
3.15
2.87
1.65
3.78
4.89
1.30
0.56
1.62
2.72
47
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Month/Year
Jan. 1984
Feb.
Mar.
Apr.
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Total 1984
Jan. 1985
Feb.
Mar.
Apr.
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Total 1985
Table 16
Total Actual Applications of
Various Wastewaters (MG/month)
to Specific Process Areas
During 1984 and 1985
Source &
Quality*
H
H
H
H
H
H
H
H + A1
H + A1
H
H + A1
H+A1
H
H
H
H
H
H
H
R
M
OF
Demonst.
1.110
0.116
0.189
1.064
2.550
0.940
0.650
0.630
2.722
-
1.073
-
.
0.908
11.952
2.788
.
2.477
0.882
-
0.801
0.496
OF
Prod.
_
-
_
1.283
26.310
9.000
6.370
4.210
4.733
-
14.216
2.230
6.710
6.153
81.215
3.497
-
3.927
5.825
1.025
-
-
Flood
Irrig.
1.090
1.340
1.787
5.167
15.260
2.130
10.900
1.038
-
-
6.372
3.452
48.536
5.107
-
-
-
-
-
Direct to
Outfall
-
-
.
-
-
-
-
-
-
-
-
-
-
-
8.610
21.140
25.436
17.413
-
-
-
H
R
H
R
R
H
R
H
M
H
M
H
M
1.340
15.545
17.706
1.199
4.668
1.968
1.261
0.473
0.469
1.680
0.910
1.298
1.201
0.933
7.489
7.275
12.929
4.780
6.430
34.220
43.447
113.249
* Source and quality symbols are: H for holding pond; R for raw influent; M for mixture of holding pond and
raw influent; and Al for alum addition.
48
-------
It needs to be emphasized at this point, however, that extensive OF irrigation of demonstration
and productions areas during the winter of 1984 verified that OF can be adequately
accomplished during the hard winters of this region. The preference of OF design and use has
merely to do with pretreatment levels, pond holding capacity, soil types, and discharge quality
limitations for both summer and winter operation.
Quality
The total treatment plant discharge waste from the outfall line must meet the NPDES limits
listed in Table 17. Monthly average values obtained for the seven limited parameters at various
process locations are listed later in this section. Only the monthly limitations, therefore, can be
discussed specifically, however, additional general comments will be made from study of the
original daily data sheets. More specific discussion of each of these and other parameters are
included in the OF Demonstration Site section. Facility groundwater qualities are also
considered.
PHOSPHORUS
Since P was of primary concern in the demonstration project, its control and management in the
overall facility will be discussed in the most detail. Table 18 lists the monthly means of T-P at
various locations throughout 1984 and 1985 and the following discussion presents some of the
management involved in meeting the NPDES limitations on T-P discharge during this period.
Sewage influent T-P to aeration pond #1 during the two-year period averaged 6.9 mg/1 and
ranged from 4.5 to 10.4 mg/1. It is interesting to note that the highest three monthly means
occurred during August through October 1984, averaging 10.1 mg/1 for this three-month period,
while during this same period of 1985 three of the four lowest monthly means occurred,
averaging only 4.7 mg/1. This change of influent T-P concentrations was probably due to an
industry's modification of waste water supplied to the town.
Aeration pond #1 reduced the T-P by 32% having an effluent average of 4.6 mg/1 and a range of
only 3.3 to 6.9 mg/1. Thus, the pond not only appreciably reduced the T-P content, but also
provided a wastewater of more uniform quality which could be valuable in producing uniform
high quality OF effluent.
Aeration Pond #2 reduced its T-P an average of only 9% to 4.2 mg/1, while the holding pond
added a reduction of 31% for a two-year mean of 2.9 mg/1. The percentage of T-P, which was
ortho, varied extensively in aeration ponds #2 and the holding pond. The variations relate to
pond water temperatures and to pond algae content. Since OF systems sometimes have
difficulty in removing floating algae, there could be an advantage to applying effluent from a
single-pond system where algae levels usually are somewhat lower.
49
-------
Table 17
NPDES Limitations for
Village of Paw Paw Outfall Line Discharge
to the Paw Paw River
Effluent
Characteristics
Carbonaceous
5-day 2(P C
Biochemical
Oxygen Demand
5-day 20o C
Biochemical
Oxygen Demand
Ammonia
Nitrogen (as N)
Suspended
Solids
Dissolved
Oxygen
pH
Total Phosphorus
(asP)
Fecal Coliform
Bacteria
Total Residual
Chlorine*
Dates in
Effect
May 1
to
Sept. 30
Oct. 1
to
Oct. 31
No. 1
to
Apr. 30
• May 1
to
Sept. 30
May 1
to
Oct. 31
Nov. 1
to
Apr. 30
May 1
to
Sept. 30
All Year
May 1
to
Oct. 31
Nov. 1
to
Apr. 30
May 15
to
Oct. 15
All Year
Minimum
Daily Daily
20mg/l
129 kg/day
284 Ib/day
-
-
5.0mg/l
32.0 kg/day
71.01b/day
-
-
2.0 mg/1
6.0 9.0
Monthly Max.
100 Ibs
-
0.07 mg/1
Maximum
30-Day Avg
13 mg/1
84 kg/day
184 Ib/day
30 mg/1
193 kg/day
425 Ib/day
30 mg/1
273 kg/day
600 Ib/day
-
30 mg/1
193 kg/day
425 Ib/day
30 mg/1
273 kg/day
600 Ib/day
-
-
1.0 mg/1
200/100 ml
-
7-Day Avg
-
45 mg/1
390 kg/day
638 Ib/day
45 mg/1
4 10 kg/day
901 Ib/day
-
45mgA
290 kg/day
638 Ib/day
45 mg/1
410 kg/day
901 Ib/day
'
-
-
400/100 ml
-
* No total residual chlorine tests were required due to extensive holding time in the lagoon system prior to land
application by surface distribution methods.
50
-------
Table 18
Total Treatment Plant Average Monthly Values
for Total Phosphorus (mg/I)
at Specific Locations
During 1984 and 1985
Holding Final
Month/Year Influent Pond#l Pond #2 Pond Effluent
Jan. 1984
Feb.
Mar.
Apr.
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Jan. 1985
Feb.
Mar.
Apr.
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
6.0
6.6
6.9
7.3
8.3
7.0
6.8
10.4
9.7
10.2
8.3
7.5
6.1
8.2
6.2
4.9
7.0
6.2
5.6
4.5
4.5
5.2
6.2
5.7
-
4.8
4.0
4.9
5.2
6.9
5.2
6.4
6.6
5.6
5.5
4.5
3.4
4.4
4.2
3.6
4.0
4.7
3.3
3.8
3.8
3.8
3.5
3.8
-
2.9
3.7
3.9
4.3
5.2
4.2
5.5
5.6
4.7
4.6
4.2
3.6
3.9
4.1
4.3
5.1
4.7
3.6
3.7
3.5
3.8
3.8
3.4
3.5
3.2
3.1
3.2
3.6
3.4
2.9
2.2
2.2
2.6
3.1
3.2
3.6
3.1
3.7
3.5
3.9
2.8
1.9
2.1
2.5
2.1
2.2
1.9
0.09
0.33
0.56
0.11
0.12
0.97
0.40
0.51
0.35
0.20
0.40
0.30
0.71
0.71
0.48
0.61
0.34
0.33
0.34
0.33
0.42
0.36
0.40
0.67
2-yrAvg. 6.9 4.6 4.2 2.9 0.42
51
-------
Discharge limitations of T-P under the NPDES permit are a 30-day maximum average of 1 mg/1
from November 1 through April 30, and a monthly maximum average of 100 pounds from May
1 through October 31. These limitations were met quite well due to conscientious management
of the multi-process facility. No violations of these P limits was noted since their inception in
November 1983. Following are some management considerations involved in directing the
holding pond wastewater flows to attain the appropriate final discharge concentrations of T-P.
The facility has three major methods of routing the effluent from the holding pond to the final
discharge location. The wastewater can be applied on up to 46.5 of OF area, applied on up to 56
ac of FI area, or outletted directly into the final discharge pipe. Between November 1 and April
30, primary consideration is given to meeting the 1 mg/1 monthly average T-P discharge
limitation and land application used only as a means of lowering the T-P discharge levels.
A 1 MGD wintertime groundwater flow of 0.1 mg/1 T-P and a 0.45 MOD direct discharge from
the holding pond with 3 mg/1 T-P would give 1.45 MGD final discharge of 1.0 mg/1 T-P, which
would meet effluent limitations. This 0.45 MGD discharge, however, would be less than the
0.56 MGD inflow to the ponds. If a 1 MGD discharge is preferred for lowering pond levels, the
following combination could be used. Direct discharge of 0.6 MGD plus flood irrigation of 0.4
MGD, which would add approximately 0.4 MGD of groundwater with about 0.2 mg/1 of P,
would give a total plant discharge of 2.0 MGD with a T-P concentration of about 1.0 mg/1. The
0.4 MGD would require 32 ac of FI area when 3 in./wk are applied. OF with its lower P removal
capability and the addition of costly chemicals usually are not considered for winter use if more
economical procedures are available.
To meet the May 1 through October 31 limitation of 100 Ib. of P per month required
considerations beyond those used in winter. OF of 46.5 ac at 2 in./wk and 56 ac of FI at 3 in./wk
would give approximately 1.50 MG of runoff at 1.8 mg/1 and 5.56 MG of drainage at 0.2 mg/1.
When this is added to approximately 6.3 MG of groundwater at 0.1 mg/1, a weekly discharge of
about 13.4 MG containing 37.1 Ib. of P would result or an average of 5.3 Ib/day. The above
values consider 60% of the OF water running off and a 40% reduction of P; 100% of the FI and
OF infiltration draining to the outlet and having P reduced to 0.2 mg/1; and 0.9 MGD of 0.1 mg/1
base groundwater flow.
While this 7.1 mg per week of irrigation would handle the ordinary weekly inflow to the plant,
the 5.3 Ib./day of P would be about 60% over the NPDES permitted level. Several alternate
solutions are available. First, sufficient alum could be added to the OF applications to reduce the
composite discharge to approximately 3.3 lb./day of P or_^econdly, OF irrigation could be
reduced until the composite P average of 3.3 lb./day is attained. In 1985, Paw Paw chose the
second alternative, since sufficient storage was already available and also to add the required
amount of alum would add chemical costs.
Obviously, this simplified winter and summer operational decisions relative to P management
had to be adjusted to account for regular demonstration site applications and special wastewater
irrigations of production areas as well as for all variations of P concentrations within specific
52
-------
processes throughout the total system. Costs associated with the existing system and possible
ranges of costs for a facility to provide overall treatment as well as P reductions by a modified
OF system are discussed under Section VII.
DISSOLVED OXYGEN
The NPDES permit limits DO only between May 1 and September 30, during which time the
daily minimum requirement is 2.0 mg/1. Average monthly DO values for 1984 and 1985 are
listed in Table 19. For these two years between May 1 and September 30, the average monthly
DO values ranged from 5.4 to 6.3 mg/1 well above the required minimum. The additional data
presented between October 1 and April 30 list DO values between 5.5 and 7.6 mg/1, indicating
fairly high and reasonably uniform year-round DO values for the facility discharge. Day to day
values are also fairly uniform easily meeting the 2.0 mg/1 daily minimum value.
BIOLOGICAL OXYGEN DEMAND
Three time periods throughout the year have specific NPDES monthly limits related to BOD, see
Table 17. Between October 1 and October 31, maximum 30-day average is 30 mg/1 or 425
Ib/day (1.7 MG of 30 mg/1 discharge), between November 1 and April 30 maximum 30-day
average is 30 mg/1 or 640 Ib/day (2.4 MG of 30 mg/1 discharge), and between May 1 and
September 30, maximum 30 day average is 13 mg/1 or 184 Ib/day (1.7 MG of 13 mg/1). During
May through September, the BOD to be determined as carbonaceous BOD, which excludes the
oxygen demand attributable to nitrification.
The BOD values of Table 19 were determined as regular or carbonaceous as required by permit,
however, since the nitrification requirements were very small all BOD values are essentially
regular. Discharge BOD qualities between 1 and 6 mg/1 plus volumes between 0.97 and 2.90
MGD easily meet the required limits throughout the year on the average. Relatively consistent
and low average BOD levels (3 to 16 mg/1) of the irrigation water, plus the mixing with large
amounts of ground water also permit easy meeting of the maximum daily discharge of 20 mg/1 or
284 Ib./day between May 1 and September 30. The two-year average BOD values of Table 19,
indicate 98.3% renovation by the lagoon system and a total treatment plant reduction in BOD
from all sources of 99.4%.
AMMONIA NITROGEN
NPDES maximum daily limit for NH3-N is 5 mg/1 between May 1 and September 30 as
indicated in Table 17. Table 19 lists average monthly discharge values for this period between
0.2 and 0.7 mg/1, which even though they are monthly averages indicate no problem meeting the
daily limit with a reasonably uniform wastewater. The two-year average values for this period
indicate 78% reduction occurs in the lagoon system and an overall reduction for the total
treatment plant of 97%. From May through September the grass is actively growing and uses
much of the NH3-N contained in the irrigation water.
53
-------
TABLE 19
Total Treatment Plant Average Monthly Values (mg/1)
for Dissolved Oxygen, Biological Oxygen Demand,
and Ammonia Nitrogen of Sewage Influent,
Holding Pond Effluent and Outfall Discharge
During 1984 and 1985
DO BOD NH3-N
Month/Year Disch. Infl. Holding Disch. Infl. Holding Disch.
Jan. 1984
Feb.
Mar.
Apr.
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Jan. 1985
Feb.
Mar.
Apr.
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
-
-
-
-
5.7
5.5
5.7
5.9
6.3
6.2
5.6
6.5
7.0
6.8
6.0
5.5
5.4
5.8
5.5
5.5
5.8
5.9
5.8
7.6
856
578
440
449
356
241
447
988
423
552
786
814
476
426
417
328
386
304
538
365
605
599
617
380
10
6
11
11
8
7
4
12
16
12
7
5
6
6
11
11
9
6
8
6
7
15
8
3
1
2
2
2
2
3
2
2
2
2
2
2
2
2
4
3
3
4
6
2
3
3
2
2
-
13.5
18.4
17.6
20.4
11.6
7.1
5.6
13.0
6.7
6.6
11.1
13.3
13.5
8.1
9.5
8.8
14.7
8.4
17.4
-
4.3
7.7
19.6
-
-
4.4
5.0
3.7
2.6
3.9
0.3
0.2
0.6
1.4
2.3
3.4
4.1
5.2
5.4
6.2
2.9
2.2
1.4
0.8
0.5
2.4
3.7
-
-
-
-
0.3
0.7
0.3
0.3
0.2
-
-
-
_
0.2
0.2
0.2
0.2
0.2
-
-
_
2-yr.Avg. 6.0 515 9 3 11.7 2.8 0.3
54
-------
PH
The two-year average pH values (Table 20) show that the influent mean of pH 7.0 increase
throughout the lagoon system to 8.4, and then decreases to 7.5 in the final discharge. The daily
outfall pH values deviate only several tenths above or below the monthly average, therefore, fall
well within the 6 to 9 range permitted by the NPDES, Table 17.
SUSPENDED SOLIDS
The year-round 30-day maximum NPDES limitation on TSS in 30 mg/1 (Table 17). Between
May 1 and October 31 this is for a maximum discharge of 1.7 MGD and between November 1
and April 30 it is for a maximum flow of 2.4 MGD. Table 20 shows that this limit was slightly
exceeded in September 1984 and in August 1985. Both months had large, intense rainfall events
and in addition during 1985 raw wastewater was being applied to the demonstration site. The
two-year average values indicate that the pond system produced 94% renovation, while the total
treatment plant reduction in TSS from all sources was 95%. It should also be noted that 12 of
the monthly holding pond TSS average values are actually less than their corresponding final
discharge values.
FECAL COLIFORM BACTERIA
The May 15 through October 15, 30-day average maximum limit of F.Col. is 200 counts per 100
ml and the 7-day average maximum is 400/100 ml, Table 17. During the limiting period in 1984
with the irrigation of holding pond effluent, this monthly criterion was easily met (Table 20)
with all monthly average counts below 80/100 ml.
Application of raw wastewater to the demonstration site during May through August 1985
caused the exceeding of the F.Col. limitation in each of these months. During the months of
May, July, and August the monthly limit was exceeded and during the month of June the weekly
limit was exceeded even though the monthly criterion was not. Raw wastewater was
satisfactorily applied in September after an appropriately sized pump and pumping arrangement
was installed to transfer the demonstration area OF runoff to a FT area for final polishing. This
solved the F.Col. problem and also helped lower the high TSS, BOD, and P levels associated
with the raw wastewater test period.
FACILITY GROUNDWATER
Groundwater monitoring for the total facility is accomplished by securing samples from 12 wells
located as shown in Figure 11 The data obtained from these wells during October for the year
1983 through 1986 are listed in Table 21. Only once-a-year data are required for each of this
parameters except for static water elevation, chloride, and specific conductance which are
required on the monthly basis. Study of the monthly values of these three parameter, however,
has no major trends different from the yearly values.
A comparison of data from the ten wells nearest to the irrigation fields indicate a 2-foot average
rise in the static water elevations between 1983 and 1986, but no uniform trends in any of the
other parameters.
55
-------
Table 20
Total Treatment Plant *Average Monthly Values* for
pH, Suspended Solids, and Fecal Coliform of
Sewage Effluent, Holding Pond Effluent, and
Outfall Discharge During 1984 and 1985
Month/Year
Jan. 1984
Feb.
Mar.
Apr.
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Jan. 1985
Feb.
Mar.
Apr.
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Infl.
7.3
7.3
7.5
7.3
7.2
7.6
7.7
6.7
7.2
6.7
6.3
6.4
7.2
6.9
6.9
7.1
6.9
7.0
6.8
7.1
7.4
6.4
6.4
7.3
pH
Holding
7.9
8.0
8.3
8.3
8.0
8.0
8.2
8.9
9.0
9.1
8.8
8.3
7.9
7.8
7.8
8.4
8.2
8.6
8.9
9.0
8.5
8.8
8.3
8.2
Disch.
7.9
7.8
8.1
8.0
7.6
7.6
7.4
7.4
7.4
7.4
7.4
7.4
7.6
7.2
7.5
7.6
7.3
7.5
7.5
7.4
7.5
7.5
7.4
7.7
Infl.
420
362
256
280
275
309
361
478
339
429
483
362
499
376
421
321
278
261
303
258
578
298
1590
242
SS
Holding
17
5
18
17
17
27
20
116
59
35
15
17
12
13
20
26
11
• 10
14
16
14
32
32
28
Disch.
11
9
19
13
19
14
10
16
39
19
13
26
14
16
22
25
25
20
16
34
22
19
20
12
F.Col.
Discharge
13
75
9
38
46
22
520
122
350
490
68
22
2-yr. Avg.
7.0
8.4
7.5
407
25
19
148
SS units are in mg/1; pH is in standard units; and F.Col. is in counts per 100 ml.
56
-------
Table 21
(page 1 of 2)
Total Treatment Plant
Groundwater Monitoring Data for
1983,1984,1985,1986
- - Well #1 - -
1983 1984 1985 1986
Stat H20 Elev
Chloride
Spec. Cond.
pH
Total Hardness
Total Alkalinity
Ammonia Nitrogen
Nitrate Nitrogen
Nitrite Nitrogen
Total Phosphorus
MB AS
Bicarbonate
Sulfate
Calcium
Sodium
Magnesium
728.58
109
900
7.4
354.2
337.7
0.16
0.1
0.05
0.04
0.053
10.5
93.2
60.8
32
728.83
102.8
910
8.2
341.4
317.1
0.17
0.33
0.05
0.03
0.025
193.3
33.7
80
57.2
34.4
729.92
117
1120
7.57
526.6
422.1
0.25
0.05
0.05
0.41
0.02
257.3
27.7
140
65
43
732.33
103.6
1050
7.9
443.5
420.2
. 0.13
0.05
0.05
0.06
0.028
256.1
7
110
74
41
Stat H20 Elev
Chloride
Spec. Cond.
pH
Total Hardness
Total Alkalinity
Ammonia Nitrogen
Nitrate Nitrogen
Nitrite Nitrogen
Total Phosphorus
MB AS
Bicarbonate
Sulfate
Calcium
Sodium
Magnesium
- - Well #3 - -
1983 1984 1985 1986
733.52
47.7
550
8
751.9
275
0.29
0.05
0.05
0.1
0.006
8
109.6
17.6
65.2
- - Well #2 - -
1983 1984 1985 1986
730.06 733.47 733.06 734.64
1.4
450
7.9
256
249
0.22
0.07
0.05
0.1
0.006
11.5
46
8.2
21.6
0.5
400
8.1
213.3
205.8
0.21
0.18
0.05
0.17
0.025
125.4
16.5
54.4
2.7
18.8
0.5
402
7.9
222.9
197.4
0.24
0.05
0.05
0.04
0.02
120.3
15.8
57.6
2.6
19.2
0.7
405
8
250.5
207.1
0.2
0.05
0.05
0.04
0.02
126.2
17
69
2.6
19
- - Well #4 - -
1983 1984 1985 1986
733.27
36
550
7.8
533.5
369.6
0.33
0.06
0.05
0.63
0.02
242
24.9
151
13.6
38
735.68
31.4
580
8
510.2
369.5
0.28
0.05
0.05
0.04
0.02
225.2
26
140
14
39
739.61
150
900
7.4
308.4
246
0.46
0.05
0.05
0.08
0.006
13
82.8
65.8
26.8
735.52
114.1
750
7.9
215.6
190
0.32
0.17
0.05
0.03
0.025
115.8
17.1
56
58
18.4
738.86
101
740
7.7
214.4
205.8
0.35
0.05
0.05
0.04
0.02
125
14.1
60.8
67
15.2
57
-------
Table 21
(page 2 of 2)
- - Well #5 - -
1983 1984 1985 1986
Stat H20 Elev
Chloride
Spec. Cond.
pH
Total Hardness
Total Alkalinity
Ammonia Nitrogen
Nitrate Nitrogen
Nitrite Nitrogen
Total Phosphorus
MB AS
Bicarbonate
Sulfate
Calcium
Sodium
Magnesium
730.05
1.7
400
8.1
206.2
194
0.12
5.1
0.05
0.05
0.006
11.5
40
6.6
20.8
730.71
12.4
418
8
184.6
178.5
0.1
3.6
0.05
0.03
0.025
108.8
12.8
43.6
9.8
18.4
730.63
6
362
8.1
177.8
130.2
0.18
9.15
0.05
0.04
0.02
79.4
12
44.8
2.5
16
31.88
8.8
458
8.1
241.3
198.9
0.1
7.48
0.05
0.04
0.02
121.3
12
62
11.2
21
- - Well #7 - -
1983 1984 1985 1986
Stat H20 Elev
Chloride
Spec. Cond.
pH
Total Hardness
Total Alkalinity
Ammonia Nitrogen
Nitrate Nitrogen
Nitrite Nitrogen
Total Phosphorus
MB AS
Bicarbonate
Sulfate
Calcium
Sodium
Magnesium
728.54
47.7
900
7.3
548.7
356
0.8
0.23
0.05
0.1
0.026
100
108
30.4
43.6
728.96
10.4
720
7.6
343.5
262.5
0.4
0.15
0.05
0.04
0.025
160
123
96
12.3
25.2
728.79
8
720
7.6
475.6
255.6
0.37
0.05
0.05
0.39
0.04
156
148.5
141
8.8
30
729.87
7.4
1100
7.6
739.4
326.8
0.53
0.05
0.05
0.04
0.02
199.2
345
212
11.6
51
- - Well #6 - -
1983 1984 1985 1986
735.66
30.4
500
7.7
266.4
299
0.3
0.25
0.05
0.06
0.006
19.5
91.2
9.6
23
735.74
8.9
485
8.2
225.9
233
0.1
0.18
0.05
0.04
0.025
142
25.3
58.8
5.6
19.2
735.32
16
570
8.2
278.4
244.6
0.1
0.05
0.05
0.04
0.02
149
30.2
75.2
8
22
- - Well #8 - -
1983 1984 1985 1986
730.12 731.54 725.87 732.04
16.9
600
7.7
353.9
308
0.34
0.05
0.05
0.05
0.006
56
82
9.2
30
10.8
615
8.2
305.7
229
0.1
0.12
0.05
0.06
0.025
139.6
97.5
75.6
3.3
28.4
9
690
8.2
313.8
276.2
0.1
11
0.2
0.04
0.02
168
26.2
80.8
5.6
27.2
7.8
750
8
428.9
243.6
0.1
0.05
0.05
0.04
0.02
148.5
165
119
3.1
32
NOTE:
- Units are in mg/1 except pH, which is in standard units, specific conductance in micro mhos,
and water elevation feet.
- Data were taken each year in October.
- Well #3 was dry in 1984
- Road construction prevented taking 1986 data for Wells #4 and #6.
- Well #12 is dry and no data are given.
58
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SECTION VII
COST CONSIDERATIONS
The cost for the overland flow treatment process is discussed in two areas; construction cost and
operational cost.
CONSTRUCTION COST
In 1980 and 1981, 56 acres of basically flat flood irrigation fields were modified to create 46
acres of sloping overland flow fields. The slope for the overland flow field was created by
cutting and filling to produce uniform slopes. The existing high groundwaters (one to four feet)
meant only shallow cust were possible. The net result was a design which has low slopes of
1.2% and 1.6% which balanced the cuts and fills and minimized the depth of cut.
The major cost to construct the overland flow fields was the earthwash to modify the existing flat
areas to sloped fields. Another component of cost was the construction of additional access
drives between adjoining fields. Major access drives were build up and gravelled due to
anticipated high traffic. Vehicles should not travel on the slope.
To handle the effluent from the overland field, construction of swales or ditches was required.
The effluent from all the fields was then combined to a single discharge.
The existing piping to each of the flood irrigation fields was reused. The vertical heads which
previously irrigated the flood irrigation fields were retrofitted with valves and adapter to direct
the water to the gated irrigation pipe used on the overland flow fields.
The cost for the earthwash items which includes the regrading, access drives, ditches and swales
was $261,000 which equals $5,700 per acre.
The overland flow piping which included the existing header piping modifications, overland
flow irrigation piping and the special piping for the demonstration (project) was $348,200 or
$7,600 per acre.
The piping required to combine the effluent of the overland flow fields and flood irrigation
fields was $378,000. The new discharge permit required the Village to combine three previous
discharge locations into one. Since the piping system was necessary for both flood irrigation and
overland flow, the cost per acre for the 102 acres equals to $3,700 per acre.
OPERATIONAL COST - OVERLAND FLOW FIELDS
An analysis of the operational cost is provided for the overland flow treatment process and is
described by the routine and related labor cost and the resultant rate to the customers of Paw
Paw. The demonstration project however is not representative for a full-scale plant operation,
therefore, an estimate is based on the operation of the completed production overland flow areas
and actual budgets of the Village.
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The overland treatment system operational components include:
1. Electrical Cost:
The only electrical cost associated with the overland flow fields is pumping cost. Under
most circumstances at Paw Paw, holding pond effluent can flow to the overland flow
fields by gravity since the fields are 5 feet above the bottom. If the holding pond has
only 5 feet of water, the irrigation systems are normally not used since the flows to the
plant are well below the plant's capacity. Therefore, on an annual basis the electrical
cost budgeted for overland flow is incidental.
2. Labor Cost -General Operations and Maintenance:
The labor involved on the overland flow process is the major operational cost. Time is
required for turning the valves to turn the water on and direct the water to the proper
fields, check the fields for proper volumes, equalized rates of flow and erosion, and later
in the day to shut off the system. All the fields can be handled by one person with three
hours at start-up and one hour at shut-down. During raw wastewater applications, more
labor was required due to the concern of plugging gated pipes and odor control. The
estimate includes labor and equipment rental for the vehicle required to move around
with at the plant.
Erosion on the overland flow slopes has been almost non-existent, therefore, no time has
been spent in repairing the fields.
Mowing of the fields is budgeted for 6 times a year. Paw Paw has a 12-foot wide mower
system which allows them to complete the mowing of all 46 acres of overland flow in
about 1 to 1-1/2 days. The cost estimate includes labor and equipment rental of a tractor
and mower.
The grass at the gated pipes requires maintenance. The easiest method the Village has
found was to use a vegetation killer around the gated pipes instead of trying to mow or
cut the grass. This application is done once a year each spring.
While operating the overland flow system on a production basis, some sampling and lab
analysis is required, but not nearly the effort as was done on the demonstration project.
The total plant effluent is monitored whether the Village is irrigating or not irrigating,
and therefore not included in the overland flow process cost. The fields will require
occasional grab samples for monitoring of phosphorus levels and, less frequently, other
parameters.
The estimated weekly cost of operations (including labor, equipment rental, pro-rating
mowing and weed killer) is $416. Based on 3"/week flow to all the production fields, a
total of 4.17 MG can be treated at a cost of about $1OO per million gallons. The cost
would increase per million gallons if all the fields (except for the allowance for one to
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rest) are not being irrigated, since the labor cost would remain fairly constant. It should
be noted that the amount of acreage involved has a minor bearing on the cost since there
is not much change from the irrigation of one field to all the fields.
3. Chemical Cost:
Based on the present operation and flexibility of the Paw Paw treatment system, chemical
addition is not required for final treatment of holding pond effluent and is not budgeted.
For a system which treats partially treated wastewater, chemical addition may be required
for phosphorus reduction and control of fecal coliforms in the final effluent.
4. Replacement Cost:
Equipment and piping replacement is required over time. Mechanical equipment usually
has a life of 10 to 20 years. Piping is normally assumed a life of 40 to 50 years.
The overland flow system has only a minor amount of equipment with the flow meters
being the only major item. Piping above ground is aluminum. Piping below grade is
corrugated metal pipe which has occasional leaks.
The total replacement budget on an annual basis is estimated at $3,000 per year or the
equivalent of $16 per million gallon based on 3 "/week application year-round.
The overland flow operational cost is summarized in the following section.
OPERATIONAL COST - PAW PAW TREATMENT SYSTEM
The operational cost of the overland flow system is a fraction of the total cost of operating the
Paw Paw Treatment Facility. The village's operational budget follows:
Overland Flow
Operational Component of Cost Component Total Cost
Billing and Meter Reading Cost -0- $ 18,000
General Labor (including lab) 8,900 60,000
Electricity -0- 53,000
Equipment Rental 2,000 6,000
Operating Supplies (including lab) 500 12,500
Replacement/Improvements 3,000 25,000
Miscellaneous Cost 1,000 15,000
$15,000 $189,500
The $15,000 represents less than 10% of their total treatment plant budget. Based on treating
25% of their total flow of 210 million gallons, or 52 million gallons, the $15,000 annual cost
equates at a cost of $290 per million gallons.
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SECTION vin
SUMMARY
Whereas specific conclusions and recommendations are listed earlier in this report, the material
presented here will be more general and include commentary. Four broad areas, which
collectively encompass the objectives presented under the introductory section are considered.
These four involve the OF flow area, the influent, the effluent, and the management of the three.
Comparisons between this project and general OF design process guidelines listed in the 1984
EPA Manual are also made.
OVERLAND FLOW AREA
The OF demonstration site and the production fields involved slopes from 1.2 to 2.5% with slope
lengths from approximately 150 to 200 ft and included seeded grass fields and sodded areas. All
areas were constructed from previously leveled FI lands having limited permeability. The OF
areas were carefully constructed and all slopes, lengths, and grass establishment methods
functioned very well under OF applications.
The uniformly sloped areas which receive the wastewater for OF treatment often are called
terraces. Terrace lengths of 150 to 200 ft used in this project are at least 50 ft longer than the
manual generally recommends. These longer terraces, however, fitted well into the modification
of the existing FI fields, required less original cost to construct and less labor to operate, and are
easier to mow. Also, soil permeability due to original clay content and extensive working was
sufficiently low so that 40 to 100% of the applied wastewater would run off. The 1.2 and 1.6%
terrace slopes (lower than the manual recommended 2-8%) of the production OF fields worked
quite satisfactorily, causing no water pooling problems. Low slopes provide better lateral
distribution of the OF and a longer time of contact for better renovation as the wastewater moves
from the top of the terrace to the outlet drainage channel.
As noted in the Manual, a well established vegetative cover is essential for the efficient
performance of OF density rates in a tall fescue and Kentucky bluegrass mixture with ryegrass as
a nurse crop and then mulched. Immediate availability of wastewater for irrigating and the
return of the first several cuttings to the site aided in establishing a very dense vegetative cover.
Grass cover of the demonstration site, however, was accomplished by sodding. This permitted
the best management for establishing an exceptionally high quality grass; it permitted full scale
wastewater applications with good renovation at least one year earlier than if the grass were
seeded at the end of construction, and it assured an erosion-resistant surface to maintain the most
ideal terrace surface as constructed.
The thicker the grass stand the better the lateral distribution of wastewater from gated-pipe
applications. Existing low infiltration rates plus the additional soil working should have caused
very low infiltration rates. Under the conditions of no rain and application levels of 2 to 4 in.,
only from 40 to 65% of the water applied ran off. This was probably due to high quantities of
plant use, to plant roots keeping infiltration high, and to much of the soil being fine sands. With
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more rain, more water amounts, and more rapid application rates, runoff percentages were
higher, approaching 100%. With less of each of these three, a greater percentage of the water
came into more intimate contact with surface soil and upper plant root zones, producing a higher
level of renovation, especially of P.
INFLUENT AND APPLICATION ASPECTS
Three types or qualities of wastewater were applied to the demonstration site — holding pond
effluent, raw wastewater, and a mixture of the two. Application levels for these wastewaters
were 3, 6 and 9 in./wk for the holding pond effluent and 2, 3 and 4 in./wk for the other two. The
rate of pumping to the three demonstration areas, each of 1.66 ac in size, usually was 360 gpm.
This rate was proportioned to 60, 120 and 180 gpm for the holding pond effluent, giving
equivalent average application rates of 0.08, 0.16, and 0.24 in./hr. For the other two
wastewaters, it was proportioned to 80, 120 and 160 gpm, giving equivalent average application
rates of 0.11, 0.16 and 0.22 in./hr.
The various methods of operation used in irrigating the three types of wastewaters each
essentially met the basic Manual criteria for lengths of application periods. For any one area, the
minimum application period was 6 hr, the maximum application period was 16 hr, and the
maximum non-irrigation period during the actual testing duration was between 2 and 3 days.
Application of the three wastewater types to the demonstration areas, also, verified the Manual's
ascertainment that OF systems are capable of performing satisfactorily with only minimal levels
of preapplication treatment. Various levels of preapplication treatment, however, carry with
them different degrees of distributional considerations.
Physical distribution of the holding pond effluent by gated pipe was very good, caused few
problems, and required little labor. While the distribution of the comminuted raw sewage was
adequately accomplished, the wastewater was not as uniformly distributed over the field, caused
odor problems, and required a reasonable amount of labor to keep the gates unplugged, to keep
all organic build-up away from the gates, and to keep all equipment operating properly.
Distribution aspects of the mixed raw wastewater and holding pond effluent improved over the
wastewater alone and required about 60 to 70% holding pond effluent to keep down odor levels.
When choosing the degree of wastewater pretreatment and/or application method, one should
consider more than merely low installation and low energy costs. Plugging of gates and organic
build-ups near gates causing the freezing of wastewater in distribution lines added to labor
requirements and was part of the decision to stop irrigation during winter. Supporting
distribution pipes 6 in. or more above ground level and/or using a higher pressure system to
reduce plugging, to keep organic material away from outlets, and to reduce labor requirements
would permit continuing applications during winter.
While wintertime OF irrigation is possible and may be preferred by some communities, the use
of a lagoon in conjunction with the OF system has a number of advantages. A month to six
weeks of lagoon storage between minimum and maximum operating depths would permit a good
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factor of safety for distribution system down-time due to mechanical failure, crop harvesting, or
extremely harsh climatic conditions. The lagoon also would function to level-out peak
concentrations of pollutants, reduce the total land area required for treatment, and provide a more
acceptable wastewater for labors to handle.
EFFLUENT REQUIREMENTS AND LOADING GUIDELINES
This section will concentrate primarily on TSS, NH3-N, BOD, T-P, and F.Col. bacteria, which
are parameters having NPDES limits for final discharge effluent. When irrigating holding pond
effluent, 24 sets of winter and 30 sets of summer data showed that effluents under each regimen
easily met NPDES requirements, except for T-P under both regimens. Actually, four of the five
parameters showed little difference in reduction between levels attained during the seven
warmest months and the four coldest months, no November data were used. The concentration
levels of NH3-N obtained in summer were lower than those obtained in winter. These low
values were probably due to crop uptake, since the total NH3-N applied was less than crop
requirements.
These data from application of holding pond effluent compare favorably with those implied in
the Manual. That is, for wastewater having a high level of preapplication treatment, 7-20 in./wk
application should still meet normal discharge requirements. Also, irrigating under harsh winter
conditions and still meeting secondary effluent requirements is possible. In addition, the
attainment of very low T-P levels from the OF process is not possible under winter or summer
conditions. Since holding pond effluent was fairly high quality wastewater, guideline
information was secured primarily from the application of the other two types of wastewater.
TSS concentrations of approximately 200 mg/1 were reduced to <20 mg/1, while concentrations
of nearly 350 mg/1 were reduced to between 15 and 28 mg/1, indicating guidelines for this
parameter under these conditions. Influent NH3-N levels of 4 to 5 mg/1 under the colder
regimens were reduced to between 0.5 and 1.0 mg/1, while under summer regimens influent
levels of 17 mg/1 were reduced to between 1 and 2 mg/1 and influent levels of 3 mg/1 were
reduced to <0.1 mg/1. These data indicate that OF could serve well as a final polishing process
for meeting summertime low discharge levels of NH3-N.
Influent BOD concentrations of 200 mg/1 were reduced to <20 mg/1, concentrations of about 400
mg/1 were reduced to between 20 and 40 mg/1, whereas a 507 mg/1 mean influent concentration
gave average effluent concentrations of 83, 136 and 158 mg/1 for the 2, 3 and 4 in./wk areas,
respectively. These data indicate 300 mg/1 and 3 in./wk as a maximum application guideline
under these conditions for meeting the 30 mg/1 effluent requirement. However, if odor is a
potential problem, this limit may need to be reduced to 200 or 250 mg/1. The 300 mg/1 and 3
in./wk application is an average loading of only 29 Ib/ac/day, which certainly should not stress
the grass. For high loading rates of high strength wastewater, a method of more uniformly
distributing the wastewater over the field should be considered.
64
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A substantial amount of long-term data from industrial OF systems show much better effluent
BOD quality than listed above. For example, the OF system at Campbell Soup Company in
Paris, Texas has been treating an applied BOD concentration of over 600 mg/1 for over 20 years
with an effluent quality of about 5 mg/1 at similar application rates. These apparent differences
between the Paris, Texas and the Paw Paw, Michigan results could be due to differences in BOD
types, distribution procedures, OF site vegetation quality, harvesting procedures, average
climatic conditions, soil conditions, or general neighborhood expectations, as odor levels,
aesthetics, and crop use. Extensive literature differences in expected results, emphasize the need
for communities and/or consulting engineering firms contemplating use of the OF process to
evaluate carefully the unique and dynamic differences among OF systems.
T-P concentrations of raw wastewater were reduced from 3 to 6 mg/1 influents to 1.1 to 2.7 mg/1
effluents and of the mixture of raw and holding pond wastewaters, they were reduced from 3.1
mg/1 influent to between 0.5 and 0.9 mg/1 effluents. Both types of wastewaters were applied at
2, 3, and 4 in./wk. Actually, for all three wastewater types, increased application depths per
week gave reduced T-P renovation levels. To assure OF effluent T-P concentrations of <0.5 or
<1.0 mg/1, additional treatment as chemical precipitation or filtration through sand or soil will be
required.
OF effluent F.Col. counts when applying holding pond wastewater ordinarily met NPDES
requirements. When applying raw wastewater or mixtures of raw and holding pond wastewater
containing more than 25% raw wastewater, the effluent F.Col. counts were all >60,000. These
data indicate that some type of F.Col. reduction treatment needs to follow the OF process when
appreciable amounts of raw wastewater are applied and when discharge limits in the range of
200/100 ml must be met.
MANAGEMENT ASPECTS
After proper design and careful construction, OF areas must still be diligently managed. Farm
operations should be accomplished so that soil conditions are not deteriorated and that grass is
maintained in the thickest possible stand and healthiest condition. This may involve harvesting
and removal, or chopping and returning vegetation to the field; it implies the use of low pressure
tires on all equipment; and it includes performing field work when soil moisture conditions are at
their lowest practical levels. All field depressions must be eliminated, ruts must be prevented,
and excessive compaction must be avoided. These aspects, emphasized by the on-line
management at Paw Paw, are also implicit in the design manual.
When choosing the application method, one should consider more than merely low installation
and low energy costs. The method chosen must also provide flexibility to handle variations in
wastewater quantity and quality; it must consider personnel working conditions; and it must
evaluate uniformity of application relative to loading levels. The more uniform the distribution
the higher the average loading rate/acre permitted and the lower the number of acres required.
Also, the more uniform the loading at the lowest average loading level, the less odor problems.
That is, for high strength and/or raw wastewater distribution for OF systems, higher pressure
65
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sprinkler systems may be overall more appropriate than low pressure gated pipe systems. The
manual does consider the advantages of high pressure sprinkler systems and the disadvantages,
but it states relatively little about personnel working conditions, especially handling raw
wastewater.
The typical inability of OF systems to produce acceptable F.Col. counts from essentially raw
wastewater and to provide T-P effluents of <1.0 mg/1 requires consideration of other pre-
treatments or post-treatment processes. Sand filtration following OF is a possible procedure but
has not yet been adequately evaluated for general recommendation. Pre-treatment by a lagoon
system designed to operate in conjunction with OF capabilities seems the most logical solution at
this stage. This lagoon system can economically provide several months winter storage; equalize
BOD loadings; reduce peak SAR; and give partial treatment for odor reduction, better working
conditions, and a grass of higher value.
A densely vegetated, sloping soil site under heavy irrigation, functions like a saturated sponge.
A drop of water to the top immediately produces a drop of water from the bottom, which
obviously did not flow over the surface. The degree of surface flow is determined by such
factors as rate, volume, and method of wastewater application; the soil types, depths, slopes, and
condition; and the roots, surface biomass, growth rate, and type of vegetative cover. All
considerations, therefore, must be three dimensional and not merely two, even when outflow
volumes approach inflow volumes, because the outflow is not purely surface runoff. On-line and
on-site management for specific renovation levels will always be unique, especially when soils
have been extensively modified to produce the "over" land flow terraces.
66
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse be/ore completing)
1. REPORT NO.
EPA 905/9-91-002
4. TITLE AND SUBTITLE
Wastewater Treatment by Overland Flow
at Paw Paw, Michigan
5. REPORT DATE
February 1988 (Approval)
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Harry L. Bush, Earl A. Myers* and Lawrence J. Fleiss*
8. PERFORMING ORGANIZATION REPORT NO
NW/Paw Paw/Ovldflw/85712
3. RECIPIENT'S ACCESSION NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Village of Paw Paw
Department of Public Works
110 Harry L. Bush Boulevard
Paw Paw, Michigan 49079
10. PROGRAM ELEMENT NO.
A42B2A
11 CONTRACT/GRANT NO.
S00555901
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency
Great Lakes National Program Office
230 South Dearborn Street
Chicago, Illinois 60604
13. TYPE OF REPORT AND PERIOD COVERED
Final 09/80-02/86
14. SPONSORING AGENCY CODE
GLNPO
15.SUPPLEMENTARY NOTEsStephen p0lonesik,USEPA Project Officer-Ralph G. Christensen, Section
*Coauthors - Williams & Works, Inc., Grand Rapids, Michigan 49506 108A
16. ABSTRACT ~~ —' '
The effectiveness of wastewater treatment by the overland flow process was
evaluated under northern climatic conditions. The Village of Paw Paw,
Michigan treatment plant includes over 50 acres of overland flow fields of
which 46 acres were used on a full scale production basis and 5 acres were
used for detailed observations (demonstration). Wastewaters used included
raw wastewater, well treated aerated pond effluent from a 3 pond system and
blends of raw and pretreated wastewater of intermediate quality selected to
minimize field odor potential. Hydraulic loadings varying from 2, 3 and 4
inches per week for the raw wastwater to 3, 6 and 9 inches per week for
pretreated pond effluent were evaluated. Overland flow treatment performance
for below freezing and above freezing conditions is described by data
collected between 1983 and 1986. Treatment performance is reported for 11
wastewatar parameters. Supplemental tests, groundwater analyses and hydro-
logic comparisons are included. General design guidelines, construction
and operating practices, and cost aspects are discussed.
DESCRIPTORS
KEY WORDS AND DOCUMENT ANALYSIS
•b IDt"NTIFiEFS,OFEN EN'JED 7 =
Phosphorus
Overland flow
Municipal treatment
j Hydraulic loadings
:. cos ATI Held/Group
Document is available to the Public
o, c. r
None
through the National Technical Information--
Service, NTIS, Springfield, VA 22161 , None
75
67
* U. S. GOVERNMENT PRIMING OFFICE: 1991/520-533
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