EPA-600/3 77-129
November 1977
Ecological Research Series
SEPTIC TANK DISPOSAL SYSTEMS AS
PHOSPHORUS SOURCES
FOR SURFACE WATERS
Robert S. Kerr Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Ada, Oklahoma 74820
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ECOLOGICAL RESEARCH series. This series
describes research on the effects of pollution on humans, plant and animal spe-
cies, and materials. Problems are assessed for their long- and short-term influ-
ences. Investigations include formation, transport, and pathway studies to deter-
mine the fate of pollutants and their effects. This work provides the technical basis
for setting standards to minimize undesirable changes in living organisms in the
aquatic, terrestrial, and atmospheric environments.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/3-77-129
November 1977
SEPTIC TANK DISPOSAL SYSTEMS AS PHOSPHORUS
SOURCES FOR SURFACE WATERS
by
Rebecca A. Jones and G, Fred Lee
Environmental Sciences
University of Texas at Dallas
Richardson, Texas 75080
Grant No. R-804549
Project Officer
D. Craig Shew
Ground Water Research Branch
Robert S.' Kerr Environmental Research Laboratory
Ada, Oklahoma 74820
This study was conducted
in cooperation with
EnviroQual Consultants and Laboratories, Inc.
Piano, Texas 75074
ROBERT S. KERR ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
ADA, OKLAHOMA 74820
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DISCLAIMER
This report has been reviewed by the Robert S. Kerr Environ-
mental Research Laboratory, US Environmental Protection Agency, and
approved for publication. Approval does not signify that the con-
tents necessarily reflect the views and policies of the US Environ-
mental Protection Agency, nor does mention of trade names or
commercial products constitute endorsement or recommendation for
use.
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FOREWORD
The Environmental Protection Agency was established to coordi-
nate administration of the major Federal programs designed to pro-
tect the quality of our environment.
An important part of the Agency's effort involves the search
for information about environmental problems, management techniques,
and new technologies through which optimum use of the Nation's land
and water resources can be assured and the threat pollution poses
to the welfare of the American people can be minimized.
EPA's Office of Research and Development conducts this search
through a nationwide network of research facilities.
As one of these facilities, the Robert S. Kerr Environmental
Research Laboratory is responsible for the management of programs
to: (a) investigate the nature, transport, fate and management of
pollutants in groundwater; (b) develop and demonstrate methods for
treating wastewaters with soil and other natural systems; (c) de-
velop and demonstrate pollution control technologies for irriga-
tion return flows; (d) develop and demonstrate pollution control
technologies for animal production wastes; (e) develop and demon-
strate technologies to prevent, control or abate pollution from
the petroleum refining and petrochemical industries; and (f) de-
velop and demonstrate technologies to manage pollution resulting
from combinations of industrial wastewaters or industrial/municipal
wastewaters.
This report contributes to that knowledge which is essential
in order for EPA to establish and enforce pollution control stand-
ards which are reasonable, cost effective, and provide adequate
environmental protection for the American public.
William C. Galegar
Director
111
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ABSTRACT
A four-year groundwater monitoring study was conducted in
the immediate vicinity of an active septic tank wastewater
disposal system in the sandy substrate in Burnett County of north-
western Wisconsin to determine the potential for this method of
wastewater disposal to contribute to excessive fertilization of
surface waters. To monitor the movement of the effluent and the
character of the area groundwater, the following parameters were
measured in water samples collected from an array of wells located
up and down groundwater gradient from the septic tank tile field:
specific conductance, pH, alkalinity, Na , Cl , K , Mg , Ca ,
soluble orthophosphate, total phosphorus, and various forms of
nitrogen.
During the course of this study, movement of septic tank
effluent in the groundwater was indicated by measured values of
several of these parameters. However, there was no evidence
of the transport of the phosphate from septic tank effluent through
the groundwater even at the monitoring point closest to the tile
field (about 15 m down groundwater gradient from the tile field).
The results of this study confirm the conclusions drawn from
similar studies in other areas reported in the literature, that
phosphorus from septic tank wastewater disposal system effluent
is usually not readily transported through the groundwater. There-
fore, septic tank wastewater disposal systems generally do not
contribute significant amounts of phosphorus to surface waters
to contribute to their excessive fertilization.
This report was submitted in partial fulfillment of Grant
R-804549 by the University of Texas at Dallas under the sponsor-
ship of the US Environmental Protection Agency.
IV
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CONTENTS
Foreword iii
Abstract iv
Figures vi
Tables vii
Conversion Table viii
Acknowledgment ix
1. Introduction 1
2. Conclusions and Recommendations 3
3. Literature Review 5
Factors controlling phosphorus transport .... 5
Field studies on phosphate transport from septic
tank systems 6
Summary and conclusions from literature .... 18
4. Experimental Procedures and Characteristics of Area . 19
Climate 23
Qualitative description of soils and geology . . 23
Sorption tests 26
Hydrology and water quality 28
Groundwater velocity 28
Groundwater quality 30
Surface water quality 36
5. Results 38
Septic tank use 38
Observation well monitoring 38
6. Discussion 52
References 58
v
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FIGURES
Number
1 Location of Hydrologic Test Wells - Voyager
Village Development Area 20
2 Test Wells for Septic Tank Monitoring Study -
Voyager Village Development Site 22
3 Groundwater Flow Pattern - Voyager Village
Development Site 29
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TABLES
Number Pag
1 Sieve Analyses on Selected Samples - Voyager
Village, Burnett County .............. 25
2 Phosphate Sorption Tests on the Voyager Village
Development Area Soil ............... 27
3 Chemical Analysis of the Well Point Samples from
Voyager Village Project .............. 31
4 Chemical Analysis of Surface Waters in Voyager
Village Development Area (June 9, 1970) ...... 34
5 Voyager Village Septic Tank Monitoring Study Obser-
vation Well Data (February 3, 1972) ........ 39
6 Voyager Village Septic Tank Monitoring Study Obser-
vation Well Data (February 16, 1972) ....... tl
7 Voyager Village Septic Tank Monitoring Study Obser-
vation Well Data (April 17, 1972) ......... 42
8 Voyager Village Septic Tank Monitoring Study Obser-
vation Well Data (August 29, 1972) ........ 44
9 Voyager Village Septic Tank Monitoring Study Obser-
vation Well Data (October 29, 1972) ........ 45
10 Voyager Village Septic Tank Monitoring Study Obser-
vation Well Data (January 25, 1973) ........ 47
11 Voyager Village Septic Tank Monitoring Study Obser-
vation Well Data (July 26, 1973) ......... 48
12 Voyager Village Septic Tank Monitoring Study Obser-
vation Well Data (October 10, 1974) ........ 49
13 Voyager Village Septic Tank Monitoring Study Obser-
vation Well Data (January 15, 1976) ........ 51
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CONVERSION TABLE
MULTIPLY
meters
cm
liters
I/cm /day
I/day
percent/m
kg
BY
3.28
0.39
0.26
215.8
0.26
0.305
2.2
TO OBTAIN
feet
inches
gallons
gpd/ft2
percent/ft
Ibs
vni
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ACKNOWLEDGMENT
This investigation was supported by N.E. Isaacson and Asso-
ciates of Reedsburg, Wisconsin. Several employees of N.E. Isaacson
and Associates contributed significantly to the project. Particu-
lar mention is given to Ken Carlson. Also, the assistance of D.A.
Stephenson and D. Huff of the University of Wisconsin-Madison is
greatly appreciated. Further, assistance was provided by Owen £
Ayres, engineering consultants of Eau Claire, Wisconsin. In addi-
tion, support for preparation of the final report was given by the
FMC Corporation, Philadelphia, Pa., the Center for Environmental
Studies, University of Texas at Dallas, Richardson, Texas, and
EnviroQual Consultants and Laboratories, Piano, Texas.
IX
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SECTION 1
INTRODUCTION
The Voyager Village recreational development located in
Burnett County, Wisconsin, has been criticized because of poten-
tial problems of ground and surface water contamination result-
ing from septic tank wastewater disposal system effluent. The
primary concern was the potential for aquatic plant nutrient
(nitrogen and phosphorus compounds) contamination of surface
waters which could result in excessive growth of algae and
other aquatic plants in nearby lakes.
Normally, effluents from septic tank wastewater disposal
systems contain large quantities of nitrogen in the form of
ammonia and organic nitrogen and phosphorus in the forms of
ortho and condensed phosphate and organic phosphorus. A large
part of the organic nitrogen and phosphorus compounds are pre-
sent in particulate forms.- In the soil, the particulate forms
are filtered out in a relatively short distance from a tile
field. Bacterial reactions convert part of the particulate
organic forms to soluble ammonia and orthophosphate. The con-
densed phosphates are primarily derived from detergents and are in
the form of tripolyphosphate and pyrophosphate. In aerobic sys-
tems, the tripolyphosphate is hydrolyzed to pyrophosphate and
orthophosphate; the pyrophosphate is hydrolyzed to orthophosphate„
Although no data are available on the hydrolysis of the condensed
phosphates in aerobic systems such as those found near the tile
field of a septic tank system, it is reasonable to suspect that
hydrolysis will occur in groundwater systems although the rate
could be somewhat slower than in surface waters.
The ammonia and phosphate present in septic tank effluent
tends to be sorbed by the aquifer material in most groundwater
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systems. However, in the presence of oxygen in the groundwater
the ammonia will be oxidized to nitrate. The nitrate is poorly
sorbed by aquifer materials and is readily transported in ground-
water. There are some groundwater systems with low dissolved
oxygen content that tend to cause some loss of nitrate through de-
nitrification reactions to nitrogen gas. Although this reaction
is generally thought to be a biochemical process, there is evidence
that chemical denitrification occurs. It should be emphasized
that the extent of the denitrification reaction is such that the
majority of the nitrate is transported by groundwater and is not
lost as nitrogen gas.
Generally, phosphate is fixed by the soil particles in the
aquifers and normally is poorly transported in groundwater. How-
ever, in some sand aquifers, like those found in many parts of
Wisconsin, the sorption capacity of the aquifer material for phos-
phate is lower than for many clay soils. It is not possible,
however, to generally state that all sand aquifer systems will
transport phosphorus. The key to holding phosphorus within an
aquifer system is the presence of small amounts of clay minerals,
iron oxide, aluminum oxide or limestone, all of which would tend
to fix the phosphate in the soil. Therefore, a sand aquifer
system which contains some of these materials would retain phos-
phate more readily than a sand aquifer system without them.
In order to investigate the potential for phosphate and
other contaminant transport from septic tank wastewater disposal
systems that are being used in the Voyager Village development
area (Burnett County, Wisconsin) it was decided to conduct a
several-year field study which would provide data necessary to
determine the likelihood of significant phosphate transport
from the septic tank wastewater disposal systems effluent to sur-
face waters in the development area.
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SECTION 2
CONCLUSIONS AND RECOMMENDATIONS
It can be concluded from the groundwater monitoring study in
the Voyager Village development area that there was transport of
septic tank effluent down groundwater gradient from the septic
tank tile field. This was generally evidenced by patterns of
specific conductance, chloride, and alkalinity values. There was
also limited transport of nitrate in the groundwaters. During the
four-year study period, there was no evidence of phosphorus from
septic tank effluent in the observation wells down groundwater
gradient from the septic tank wastewater disposal system.
If area lakes receiving groundwater from the development area
are typically phosphorus limited, the installation of septic tank
wastewater disposal systems in the Voyager Village development area
should not degrade existing surface water quality. However, where
lakes of the area are nitrogen limited during the period of maxi-
mum algal growth, there is a potential for some increased aquatic
plant growth due to contributions of nitrate from septic tank ef-
fluent.
The results of this study strongly support the conclusions
drawn from similar studies reported in the literature, that the
phosphate present in septic tank wastewater disposal system ef-
fluent would not, in general, be expected to contribute signifi-
cantly to the excessive fertilization of surface waters.
While significant transport of phosphorus from septic tank
wastewater disposal system effluent to surface waters is ex-
pected to be rare, there are situations where this would occur.
In those situations where it is not possible to construct a
sewerage collection system, consideration should be given to
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modifying the septic tank disposal system to increase phosphate
retention capacity. There are a number of engineering questions
that remain to be resolved in order to provide some general guide-
lines for design of the modified system in order to minimize cost
and maximize phosphate removal. It is recommended that studies be
conducted to provide general guidelines on the design of modified
septic tank wastewater disposal systems to increase their phos-
phate retention capacity.
There is little need for additional research on the mechanisms
of phosphorus immobilization in soils. While there are still
several unanswered questions in this area, further work along
this line is likely to yield a rather limited amount of addition-
al information which could be used to readily ascertain whether a
particular septic tank wastewater disposal system is contributing
a significant amount of phosphate to nearby surface waters. Ques-
tions of this type have to be approached on a case-by-case basis
so that through the monitoring of an appropriate series of wells
and an understanding of ground and surface water hydrology, it
would be possible to establish whether or not phosphate transport
was occurring from a particular system. It should be possible to
develop a laboratory phosphate transport test system in which the
expected amount of transport that may occur in the field could be
estimated. It is recommended that studies in this area be con-
ducted.
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SECTION 3
LITERATURE REVIEW*
FACTORS CONTROLLING PHOSPHORUS TRANSPORT
There are a number of factors controlling phosphorus trans-
port from septic tank wastewater disposal system effluent to sur-
face waters in sufficient quantities and in available forms to af-
fect surface water quality. Based on previous studies of the chem-
istry of phosphorus in natural water systems, it is expected that
the potential of a soil to remove phosphate from septic tank waste-
water disposal system effluent is controlled by the mineralogy of
the area soils rather than by the soil particle size. A review of
the literature pertaining to reduction of phosphate concentrations
by soil and subsoil systems indicates that one of the primary fac-
tors in P removal is the tendency of phosphorus to sorb on aquifer
materials or on soil or subsurface particles. In addition, in
calcareous areas, phosphate can be precipitated as hydroxyapatite
in the groundwater system. Lee (1976b) pointed out that in hard-
water areas such as are found in the southern half of Michigan,
the likelihood of significant phosphate transport from septic tank
wastewater disposal system effluent to the surface waters is great-
ly reduced because of the calcium carbonate present in the soil
and subsoil systems.
The importance of sorption and precipitation reactions is
readily demonstrated when one examines the chemical characteristics
of groundwaters. It is rare that groundwaters have high phosphorus
content. The total phosphorus is rarely more than a few tenths of
a milligram per liter (Dudley and Stephenson, 1973; New York State
Department of Health, 1972; Stumm and Morgan, 1970). In the re-
view of phosphate removal by sands and soils by Tofflemire ejt al.
(1973), it is stated that the natural groundwater concentrations
*Standard units of measure have been converted to the metric system,
Refer to Conversion Table, p. viii, for explanation.
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often range from 0.01 to 0.06 mg/1 P. Also, according to Enfield
(1976), the phosphorus concentration in naturally occurring ground-
water is typically 0.05 mg/1 or less. As discussed by Enfield and
Bledsoe (1975), seven literature values for phosphorus concentra-
tions in ground and subsurface drainage water from agricultural
land and beneath wastewater treatment systems showed that concen-
trations generally ranged from about 0.005 to 0.1 mgP/1. The low
concentrations of phosphorus present in groundwaters can be attri-
buted to a combination of sorption and precipitation reactions.
These same reactions would be applicable to the phosphorus present
in septic tank wastewater effluents.
FIELD STUDIES ON PHOSPHATE TRANSPORT FROM SEPTIC TANK SYSTEMS
Thomas (1976) indicated that Allum used the work of Dillon
and Rigler (1975) and Viraghavan and Warnock (1976a) as support
for his position that there is limited retention of phosphorus by
soils adjacent to septic tank wastewater disposal systems. Soils
used in the Viraghavan and Warnock study, Thomas claimed, were
similar to those in Michigan. Examination of the paper of Virag-
havan and Warnock (1976a) shows that no mineralogical information
is given upon which one can judge the similarity or lack thereof
of the soils in Michigan compared to soils near Ottawa, Canada,
where their study was conducted. The authors (Viraghavan and
Warnock) had significant experimental problems in their study.
Even if the results are taken at face value, their data indicates
25 to 50 percent retention of phosphorus. This amount is con-
siderably greater than the 10 percent figure that Thomas attempted
to justify.
The other paper cited by Thomas in support of his position
was that of Dillon and Rigler (1975). Upon examination of the
retention coefficients formulated by Brandes et_ al. (1971) pre-
sented therein, in only the five coarse sands tested was the frac-
tion of phosphorus retained less than 50 percent. The other sands
and sand-silt or sandy-clay mixtures showed 63 to 88 percent phos-
phorus retention. One of these coa.rse sands had a phosphorus
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retention of 48 percent. Only two coarse sands showed retention
of less than 10 percent.
Keeley (1976), Chief, US EPA Groundwater Research Program,
stated that, in general, the only place they have encountered sig-
nificant phosphate transport in groundwaters is in association
with coarse sands, and even there, the movement in many instances
is very slow.
Henderson (1969) stated that in his investigation of Gull
Lake, Michigan, there appeared to be a relationship between the
presence of septic systems 15 m or less from the lake and the
observation of aquatic weed growth along the immediate shore. He
also stated, however, that aquatic weed growth was more frequent-
ly noticed by those residents who water and fertilize their lawns.
Visual examination of his figures showing these relationships
shows a strong relationship between residents who fertilize their
lawns and observation of aquatic weed growth in the adjacent shore-
line. Henderson's justification for the possibility that this re-
lationship may be tenuous is inconclusive since relationships be-
tween types of fertilization practices and increased aquatic plant
growth observations were not properly weighted according to num-
bers of people using each fertilization method. Based on data
given, it would be difficult to sort effects of fertilization and
distance of septic tanks from the lake.
In five samples collected in tile lines draining toward Gull
Lake, Ellis and Erickson (1969b) found that phosphorus content
varied from 0.028 to 0.07 mg/1 P, indicating negligible transport
of phosphorus from those septic tank system effluents.
In the Gull Lake investigations of the effect of phosphorus
load on distance of phosphorus movement, Ellis (1971) found that
at four of the ten sites sampled, the profiles contained so much
phosphorus, apparently from fertilizers according to Ellis, that
the determination of phosphorus movement from septic tank dis-
charge was very difficult. Three additional locations showed suf-
ficient interference from fertilizers to make the determination
of the distance of phosphorus movement from the septic tank dis-
charge difficult. He concluded that, in general, based on the
7
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remaining sites, the distance phosphorus moved increased with in-
creased soil P rating (a measure of phosphorus load from the resi-
dences ).
Ellis (1971) also studied the distance of phosphorus movement
for the various soil types in the area. All of the soil types
surrounding Gull Lake (Beliefontain sandy loam, Bellefontain loam,
Fox sandy loam, Fox gravelly loam, Fox loam, muck with fill) were
represented in the study except the Ostemo sand. The quantity of
this sand in the Gull Lake area was reported to be small. In this
part of his study, movement of phosphorus from the surface (from
fertilizers) made it difficult to assess movement from septic tank
effluent. Only four of the 16 locations showed no apparent move-
ment from the surface. In the 12 locations where estimations of
movement could be made, only three showed phosphorus movement from
the point of effluent discharge greater than 6 m. Maximum phos-
phorus movement found was 9 m. Ellis stated that until the soils
become saturated with phosphorus, nearly 98 percent of the phos-
phorus entering the ground would be adsorbed by soils. He made
the observation that 75 percent of the lawns surrounding Gull
Lake were saturated with phosphorus from fertilizers. This would
allow the phosphorus in those areas to largely pass through the
soil.
An estimation of the annual phosphorus load transported into
Houghto.n Lake, Michigan, by groundwaters, was made by Childs (1974).
This estimation was based on groundwater sample analyses, an area
water budget, and net flow calculations. It was estimated that
groundwater transports from all sources a maximum of 450 kg of
phosphorus into Houghton Lake annually. This represents 98 per-
cent removal of the estimated 18,000 kg of phosphorus discharged
annually by local residents via septic systems. Since the phos-
phorus mass is not present in local groundwaters and only trace
amounts could be adsorbed above the groundwater, Childs concluded
that phosphorus is sorbed below the water table. He further con-
cluded that it appeared that the adsorptive capacity of soil may
be as great under water saturated conditions as under aerated con-
ditions. Childs concluded that the majority of phosphorus
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discharged through septic tank systems in the Houghton Lake area
has been, and is being, retained by soils and sediments within the
zone of saturation.
In a study of six septic tank disposal systems in Nassau and
Suffolk Counties (Long Island), New York, conducted by the New
York State Department of Health (1972), it was concluded that phos-
phate reductions were rapid and almost total in the distances from
septic tank wastewater disposal systems studied. Soil porosities
at Sites 1, 2, and 3 ranged from 29 to 38 percent. The soil char-
acteristic at Site 1 was predominantly medium to coarse sand and
gravel; distance to the groundwater was 2.4m. There were two cess-
pools on the site, one receiving the majority of the waste, the
second receiving some waste and overflow from the first cesspool.
Despite the fact that the first pool was full and overflowing into
the second pool, substantial leaching from the first pool was in-
dicated. Only data from the monitoring of one pool (apparently
the first) was presented. Decreases in phosphorus content of 97
to 99 percent by 24 m downgradient from the one cesspool site
monitored were found, where total P ranged from 1.7 to 0.99 mg/1.
Between 26 and 57 percent decrease was found at 4.6 m below the
cesspool. Average percent reduction found at that site was about
4.6 percent/m. An adjustment of this decrease for dilution showed
that removal of 1.7 to 2.1 percent/m was due to factors other than
dilution in the saturated zone.
At their Site 2 (cesspool site), also in medium to coarse
sands and gravel where the distance to the groundwater was 2.4 m,
99 to greater than 99.9 percent total phosphate reduction was
found at a point 20 m downgradient where concentrations in the
groundwater varied from 0.03 to 0.6 mg/1 P. Between 32 and 69
percent reduction of phosphates was found 7.6 m downgradient from
the cesspool.
The third site in the Long Island study, on which one cess-
pool was located, contained medium to coarse sands and gravel.
Distance to the groundwater was 9m; average groundwater
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velocity was 0.37 m/day. In the first 1.5 m downgradient, in
unsaturated soils, 44 and 76 percent phosphorus reductions were
found on the two sampling dates. At 14 m, the phosphorus had
been reduced a total of 72 and 97.7 percent, respectively. Average
reductions of phosphorus were 2.5 percent/m and 9.0 percent/m
through the unsaturated soil zone (from the cesspool to the well
located about 4.6 m from the cesspool). Average phosphate reduc-
tion in the saturated zone by about 18 m from the cesspool was,
discounting decrease by dilution, 4.7 to 8 percent/m, indicating
factors other than dilution accounting for the majority of de-
crease in concentration in the saturated zone. In the limited
study of vertical migration done on this site, 34 and 52 percent
phosphorus reduction took place in the first 0.46 m of unsaturated
material beneath the cesspool.
Subsoil at Site 4 consisted of silty sand with traces of gra-
vel; distance to the groundwater was 5 m. There were two cess-
pools at the site, but only one received wastes during the study
period. Net P reductions of 98.6 to 99.8 percent were found with-
in 9.4 m downgradient from the cesspools resulting in background
phosphorus levels in the groundwaters within 9.4 m of the cess-
pools. Overall average reductions during travel through the un-
saturated zone were 25.1 and 27.0 percent/m, whereas in the
saturated zone, decreases were 15.6 and 32 percent/m, respectively.
Disregarding dilution effects in the saturated zone, 11.9 and 26.3
percent/m decreases, respectively, were found.
The Long Island, New York study also monitored two septic
tank-tile field systems, one in medium to fine sand (Site 5) and
another in sandy clay, grit and stones (Site 6). Distances to
groundwater were 1.4 and 2.4 m at Sites 5 and 6, respectively.
Their summary of percent P reduction showed 63 to 82 percent re-
duction within the Site 5 tile field. Beneath the tile field at
Site 6, P reduction ranged from 99.7 to 99.8 percent with result-
ing groundwater concentrations of 0.14 to 0.21 mg/1 P. They con-
cluded that the increase in P reduction at Site 6 could be at-
tributed to optimum conditions for phosphate reduction, namely
10
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finer soil to encourage entrapment of precipitated phosphates as
well as the relatively new unsaturated soil horizon which would
enhance adsorption potential. In addition, greater water use at
Site 5 and character of sewage produced there purportedly influ-
enced reduction. In these investigations, only total P values
were presented. The authors indicated that the ortho and total
phosphate values were essentially the same.
Hansen (1968) and Boyle and Polkowski (1970) (as cited in
Dudley and Stephenson, 1973) monitored septic tank wastewater
disposal system effluent migration in soil and groundwater adja-
cent to the system in an area of silt and loam overlying glacial
outwash sand and gravel in Wisconsin. They concluded that soil
at the site removed essentially all of the phosphorus present in
the septic tank effluent.
Dudley and Stephenson (1973) monitored migration of phospho-
rus from septic tank effluents at 11 sites in central and northern
Wisconsin. Efficient P reduction was accomplished at the septic
tank system at Site 1 (built in 1968 on the shore of an oligotro-
phic lake in outwash sand where the depth to the water table was
3.4- m) as evidenced by generally low total P concentrations at
wells downgradient from the tile field. When absorption field
effluent was sampled concomitant with observation wells about
4.6 m downgradient, 99.1 to 99.9 percent P removal was found
resulting in well concentrations of 0.3 and 0.04 mg/1 P, respec-
tively.
Dudley and Stephenson (1973) also found very effective P
reduction at their second site, a dry well system in outwash sand
built in 1965. Depth to the water table was 4 m. No concentra-
tions greater than 0.65 mg/1 P were found associated with this
area. Effective P reduction at Site 3, in medium sandy soil,
was evidenced by the fact that concentrations of total P rarely
»
exceeded 0.3 mg/1 in wells monitored adjacent to the absorption
field. Concentrations within 12 m of the absorption field were
generally in the several hundredths of a mg/1 range. That system
was built in 1971; depth to the water table was about 3 m. The
same degree of decrease was found at Site 4, built in 1969 in
outwash sands, where depth to the water table was about 2.5m.
11
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Dudley and Stephenson (1973) found that their Site 5 septic
tank (constructed in 1970) in an area of sandy loam overlying me-
dium sand where depth to the groundwater ranged from 0.6-6.4 m con-
tained high phosphorus concentrations up groundwater gradient
from the septic tank system due to natural enrichments through
nutrient flushing of organic lake bottom sediments located up-
gradient. The single down groundwater gradient observation well,
9 m from the tile field, however, contained only 0.03 to 0.11
mg/1 P during the study period, demonstrating effective P reduc-
tions from percolating effluent.
Data from Sites 6 and 7 (in clayey sand soil), according to
Dudley and Stephenson, were difficult to interpret due to sampling
difficulties and differences in sampling techniques. Those sep-
tic tank systems were built in 1968 and 1964, respectively. Low
levels of P in the pumped wells at Site 7 where depth to the
groundwater was 1-2 m did indicate a decrease in phosphorus from
the effluent, however. Groundwater directly below the absorption
field at Site 8 (apparently medium sand) showed some transport
of phosphorus and migration of P in the groundwater. This phos-
phorus would likely not affect water quality in the nearby lake
since the movement of groundwater was away from the lake at that
point.
As monitored at Site 8 well points located approximately
0.9 m on either side of the absorption field, there was generally
some lateral movement of P in the groundwater. Concentrations
ranging from about the same to 35 times greater than background
levels were found in these wells. The most elevated P concentra-
tions were found at. the well site about 3 m from the end of the
tile field. This well was located on the downgradient edge of the
septic tank. It is possible that the very high groundwater P
concentrations at that well site were the result of leakage of
the septic tank itself, rather than from tile field drainage.
Data from Site 9, in outwash sands where depth to the water
table was 3-7 m, showed P contamination in the well about 0.9 m
downgradient from the dry well (built in 1967). As was pointed
out by Dudley and Stephenson (1973) this may be due in major part
12
-------
to system design. Such a system is installed in coarse sand so
that lateral flow in the unsaturated zone in response to soil
moisture tension would be minimal. This coarse sand and gravel
substrate apparently had little or no ability to adsorb P during
the downward percolation of the effluent.
Site 10, also a dry well system, built in 1969 in a sandy
soil where the depth to the water table was 0.6-4 m , demonstrated
effective reduction of P from the effluent. This was evidenced
by low levels of phosphorus in the well located several feet down-
gradient from the dry well and in those outside the gravel fill
area.
The final site in the Dudley and Stephenson study was an
absorption field built in 1974 on about 17 m of unsaturated
outwash sand. Due to differences in sampling technique, the use
of the phosphate data generated was limited. Of six sets of sam-
ples collected at the two downgradient wells, four sets showed
higher total P concentrations at the well immediately downgradient
from the field than at the well about 9 m farther downgradient
This indicates that there was some P reduction occurring.
Periodic occurrence of elevated phosphorus levels in up-
gradient wells at a few of the sites pointed to some local re-
versals of gradient near the center of the groundwater mound at
the discharge. Two of those sites, however, were recharged by
lake water which may have contributed to the higher upgradient
concentrations.
It was demonstrated in this study that although phosphorus
enrichment of groundwater occurred in a few coarse sand systems,
effective decreases in phosphorus took place in medium and fine
sand soils. In most sites monitored, low total P concentrations
were found in well stations 4.6 m downgradient from input, and
beyond.
Viraghavan and Warnock (1976b) studied migration of phos-
phorus from an experimental tile field in sandy loam, silt loam
to silty clay, loam soil in Ottawa, Canada. One sample set showed
apparently effective P removal by a point 9.1m from the
13
-------
experimental tile field. It appeared from diagrams presented that
concentrations in wells beyond that point could have been influ-
enced by flow from laterals of the main septic system adjacent to
the experimental field. Although Viraghavan and Warnock concluded
that the decrease of phosphate achieved in this study was not high,
it was difficult to determine patterns of removal from the data
presented.
Reneau and Pettry (1976) conducted a study during 1972-1974
in Chesterfield County, Virginia on Goldsboro sandy loam and
Varina sandy loam to determine effects of septic tank effluent
on soil P fractions and their distribution. Both soil areas were
moderately well drained and had seasonally perched water tables.
The system on Varina soil had been in use for approximately 15
years, receiving an estimated 2700 I/day effluent. The system in
the Goldsboro soil was four years old and received an estimated
770 I/day effluent,
Data from 46 groundwater samples adjacent to the drainfields
in Varina soil indicated that dissolved P consisted primarily of
soluble ortho P with only minor contributions from polyphosphates
and organic P. In the Varina soil, increased concentrations were
found at the 89-99 cm depth. Soluble orthophosphate concentra-
tions at that depth showed a decrease from an average effluent
concentration of 5.5 mg/1 to an average of 1.05 mg/1 at 0.15 m
from the drainfield, an 80 percent P reduction. This decrease
generally continued with distance from the drainfield. At 6.1m
from the drainfield, greater than 90 percent reduction in average
soluble ortho P was found. By 12 m from the discharge, the con-
centration was an average of 0.01 mg/1 P, a 99 percent removal of
phosphate. Using the maximum concentrations found at the 89-99
cm depth 12 m from the drainfield, removal was 80 percent. Con-
centrations in the lower, plinthic horizon (all averaged at or
below 0.01 mg/1 P) according to Reneau and Pettry, showed that
that horizon was an effective barrier to vertical soluble ortho P
movement. Mo detectable soluble ortho P was found in perched
water tables not receiving septic tank effluent.
14
-------
An examination of P fractions in the Varina soil horizons
at different depths downgradient from the drainfield area showed
increased concentrations, as compared to the control profile, of
all fractions in the top 18 cm at 0.15 m from the drainfield.
Reneau and Pettry attributed this to previous fertilization prac-
tices. Phosphorus concentrations at 0.15 m from the drainfield
reached a maximum in the B21t and B22t horizons (41-76 cm depth)
and decreased rapidly in the plinthic horizon (beyond 76 cm
depth). The accumulation of P from septic tank effluent, they
concluded, was concentrated in the argillic horizons. The in-
crease in "fixed" P in that horizon at 0.15 m reflects not only
water movement in a horizontal direction above the plinthic hori-
zon, but also the influence of soil physical and chemical proper-
ties of these horizons on P fixation. At 3 m from the drainfield
in the B21t and B22t horizons, there was essentially no difference
in P fractions from those found in the central profile.
At the Goldsboro location, soluble ortho P was present pri-
marily at the 142-152 cm sampling depth. From an average drain-
line concentration of 11.8 mg/1 P, average concentrations were
decreased 92 percent by 0.15 m from the tile field. Concentra-
tions generally decreased at that depth with increasing distance
from the field. At 3 meters from the tile field, there had been
a reduction of 98 percent, to an average of 0.21 mg P/l. On the
average, there was no detectable phosphate at this depth, 13.5 m
from the drainfield. Maximum concentrations there were 0.01 mg
P/l. In the Goldsboro soil, the septic tank effluent generally
had little influence on soil P fractions at 0.15 m. This was
attributed to the youth and limited use of the system.
Reneau and Pettry stated that during periods of lower water
tables at the Goldsboro site, soluble ortho P apparently moved
primarily in a vertical direction in the saturated zone below
the drainlines until the perched water table or restricting layer
was intersected. Horizontal movement then occurred at the 142-
152 cm depth. There was no indication that the phosphate moved
into the 432 cm depth which was in the permanent groundwater table.
15
-------
Smith and Myott (1975) reported that 57 percent of the 1.5
million people in Nassau County, N.Y. were served by sewers. The
remaining population discharged 230x. 106 I/day sewage 'into the
ground. They undertook a study to determine constituents of sewage
origin in groundwater during 1971 and 1972. It indicated that the
elevated levels of phosphorus (0-10 mg P/l) attributed to cesspool
leachate were found in shallow observation wells but not in the
selected Magothy aquifer wells beneath the more shallow aquifer.
Beek ejt al. (1977a) conducted a two-year study on a sewage
farm drainfield on sandy soil near Tilburg, the Netherlands.
This farm had been in use for 50 years during which time the
drainfield was intermittently flooded (generally once a month).
Averaged over the two-year monitoring period, they found removal
of total and orthophosphates up to 96 percent between sewage water
and field drainage water. They found that the accumulation of soil
phosphates was limited to the top 50 cm soil layers; nonflood soils
showed low levels of soil phosphate in the top 75 cm of soil com-
pared with flooded soil. Adsorption reactions were proposed at
the mechanisms involved, because of the high efficiency of phos-
phate removal despite limited contact with the soil.
Comparison of the chemical forms in which phosphates accumu-
lated in sandy soil plots flooded intermittently for 30 years and
for 50 years was made by Beek et_ al. (1977b). They showed that
the distribution patterns of the different phosphate fractions
were virtually the same in both plots. Because of this, in ad-
dition to the fact that the Al-combined phosphates prevailed, it
was concluded that phosphate retention in these soils was still
mainly governed by reactions with aluminum. The presence of ac-
tive Al compounds, either available in the soil system prior to
flooding or added as components of sewage water, according to
Beek ejt al., will determine the ultimate storage capacity of the
soil for phosphate binding in that soil.
Lee (1976a) studied the groundwater transport of nutrients
(N and P) to Lake Sallie located in glacial outwash terrain of
west central Minnesota. Evaluation of the contributions of
16
-------
nitrogen and phosphorus was based on groundwater samples collected
using seepage meters placed on the lake bottom (7 to 17 m from
shore) adjacent to a residential and/or cropland area. Lee con-
cluded that the contribution of phosphorus from groundwater in-
cluding septic tanks near the lake was insignificant compared to
the surface water phosphorus load.
It is concluded from these field studies on transport of
phosphorus from septic tank wastewater system effluents that the
likelihood of significant transport is small. Several other in-
vestigators who have reviewed this topic have reached similar
conclusions. According to Okun (1972), in unsewered areas, which
include about 30 percent of the total US population, although
waters from the wastewater disposal systems may reach lakes and
streams, the phosphates are held in the ground. He concluded
that private sewage disposal systems are of little consequence
to the eutrophication problems of the US.
Corey et al. (1967) estimated principal sources of phosphorus
for Lake Mendota, Wisconsin. The contributions from private sew-
age systems (septic systems) were estimated by assuming that 5
percent of the phosphorus in the sewage eventually reaches sur-
face waters. Corey et al. estimated that septic tank wastewater
disposal systems contributed a minor fraction (2 percent) of the
total phosphorus input.
It has been estimated that private sewage systems contributed
2.2 percent of the phosphorus load to surface waters of Wisconsin
(Wirth and Hill, 1967). This contribution figure was based on
the assumptions that all nutrients contributed by private sewage
systems reached surface waters and that the systems were used
year-round. They stated that not all systems were located in
close proximity to surface waters and that it was likely that two-
thirds or more of the septic systems on water front properties
are not used for more than three or four months per year ,
Therefore, it is unlikely that septic tank wastewater disposal
systems would represent significant sources of phosphorus that
could contribute to the excessive fertilization of surface waters.
17
-------
SUMMARY AND CONCLUSIONS FROM LITERATURE
It has been demonstrated by previous studies that the poten-
tial of a soil to remove phosphate from septic tank wastewater
disposal system effluent is controlled by the mineralogy of the
area soils, rather than by the soil particle size. In field
studies, it was found that most soils, even medium sandy soils,
exhibit substantial ability to reduce phosphate concentrations.
Reductions found were typically in excess of 95 percent within
relatively short distances from effluent sources. It has also
been shown that the capacity of a soil to reduce effluent phos-
phorus concentrations is not necessarily finite.
It can be concluded, based on these studies, that it is un-
likely that, under most circumstances, sufficient available phos-
phate would be transported from septic tank wastewater disposal
systems to significantly contribute to the excessive aquatic
plant growth problems in water courses recharged by these waters
18
-------
SECTION 4
EXPERIMENTAL PROCEDURES AND CHARACTERISTICS OF AREA
To determine soil characteristics, groundwater flow patterns,
and general groundwater quality in the study area, 18 test wells
were installed (by Stephenson) in July, 1970. Figure 1 shows
the locations of these wells as well as those already present in
the area. All test holes were drilled to 3 meters or greater be-
low the water table elevation found on the date of drilling. Sand
point piezometers (3.21 cm diameter) were installed in each test
hole to provide a continuing capability for measuring the ground-
water evaluation.
In an effort to evaluate potential /phosphate transport in the
development area several preliminary sorption tests were run on
area soil samples provided by Owen Ayres £ Associates. Analyses
were made by taking approximately two grams of the sample pro-
vided, placing it in a 300 ml flask to which 100 ml of a 10 mg P/l
solution was added. Each flask was capped and shaken for 24 hours.
At the end of this period, each sample was filtered through a
0.4-5 micron pore size membrane filter that had been pre-washed
with distilled water. The phosphate content of the filtered solu-
tion was determined by the phosphomolybdate method (APHA et_ al.,
1965). Blanks were carried through the tests to compensate for
losses due to sorption of phosphorus on glass during filtration,
etc. The amount of phosphate lost to the sand was determined by
subtracting the phosphate concentration remaining in the solution
after contact with the sand from the initial phosphate solution
added to the sandy mixture. The phosphate sorbed per gram of sand
was determined by dividing the amount of the phosphate uptake by
the weight of sand used in the particular study. Each sample was
run in duplicate.
19
-------
Figure I
Location of Hydrologic Test Wells
Voyager Village Development Area
Scale: I cm* 0.6km
After Stephenson (1971).
20
-------
To obtain an estimate of the surface water quality at the
outset of the study, grab samples were collected from lakes and
streams in the area on June 9, 1970. About a month later, select-
ed wells shown in Figure 1 also were sampled. Phosphate analyses
were carried out in accordance with the phosphomolybdate method
(APHA et al. , 1965).
After the direction and general velocity of the groundwater
had been defined by Stephenson (1971), a septic tank effluent
monitoring program was established. An existing septic tank sys-
tem in the vicinity of wells 3 to 7 (an area to be serviced by
septic tank systems in conjunction with the Voyager Village de-
velopment) was chosen for monitoring. Observation wells were
placed as shown in Figure 2. Wells A-J were installed at a depth
of 1.5 m below the water table; wells K, L and M to U.6 m below
the water table. Later, during the study, two additional wells,
N and 0, were drilled also to a point 1.5 m below the water table.
Wells A-M were sampled on the following dates: February 3,
February 16, April 17, August 29 and October 29, 1972; January 25
and July 26, 1973; October 10, 197U; and January 15, 1976. On
October 10, 1974 and January 15, 1976, wells N and 0 were also
sampled.
Although the analysis program was occasionally altered dur-
ing the course of the study, the following parameters were
generally measured: specific conductance, pH, alkalinity, Na ,
Cl~, K , Mg , Ca , soluble orthophosphate, total phosphorus,
, and organic N. Phosphate analyses were carried out in
accordance with the phosphomolybdate method (APHA et al. , 1965;
APHA e_t al . , 1971; APHA et al. , 1976) or equivalent. Elevated
chloride and specific conductance values are good indicators of
the presence and movement of septic tank effluent in groundwater.
The alkalinity, calcium and magnesium concentrations can provide
general information regarding direction of effluent flow in the
groundwater but are usually not as useful as chloride and specific
conductance values in this regard. The sodium concentrations
should generally follow the chloride concentrations although they
21
-------
Figure 2
Test Wells for Septic Tank
Monitoring Study
Voyager Village Development Site
Scale: Icm = 7.6 m
J
M 2
*' 6
B
• 'WELL POINT
groundwater
After Huff and Stephenson (1971)
22
-------
are not usually as sensitive to changes in concentrations result-
ing from contamination by septic tank effluent. The potassium
and sulfate values are useful in this study only in terms of
characterizing the general content of the groundwater. Neither
measurement can be interpreted in a way as to contribute to the
overall objectives of this study. Turbidity can give an indica-
tion of the amount of suspended solids not purged from the well
prior to sample collection.
As the focus of this study is on the transport of aquatic
plant nutrients, especially phosphorus, of primary interest are
the concentrations of soluble orthophosphate, nitrate and ammonium.
Total P and organic N concentrations have little meaning in this
groundwater study as they do not give an indication of available
forms of aquatic plant nutrients that are allowed to pass through
the groundwater to potentially influence surface water quality.
CLIMATE
According to Blackman ejt al. (1966), the climate of the area
(Burnett County, located in northwest Wisconsin) is continental.
Mean temperatures drop below freezing in mid-November and freezing
of lakes follows soon after. The average date of the first freeze
in the fall is September 12; the average last freeze in spring is
May 31. The average annual precipitation for Burnett County is
about 78 cm. The average runoff is 24 cm near Rush City on the
St. Croix River. Maximum precipitation occurs in June; however,
highest runoff usually occurs during April in association with
snowmelt.
The original vegetation of the southern farm area in the
southern part of the county was oak or pine, but the second growth
timber is largely white birch and aspen.
QUALITATIVE DESCRIPTION OF SOILS AND GEOLOGY
N.E. Isaacson 6 Associates, Inc. began an investigation of
the hydrologic and hydrogeologic characteristics of the Voyager
Village development area in April, 1970. These studies were
23
-------
conducted by Stephenson (1971) and Huff and Stephenson (1971). They
found that stratified sandy soil deposits, mostly glacial drift
outwash, characterized the area. The deposits were products of
glacial melt-water stream deposition which occurred in recent
geologic time. Deposits of the last glacial episode were subse-
quently covered by younger outwash containing large, melting ice
blocks. The hummocky topography of the area was created as the
buried ice blocks melted.
The glacial drift deposits are a fine to medium grained sand;
mean grain size diameter was 0.125 to 0.5 mm. The sand deposits
could generally be vertically zoned into two rather distinct and
recurring units:
1. Sand; dark red brown; fine- to medium-grained;
sometimes silty; generally 3 to 9 m thick;
2
permeability ranges from 0.4 to 1.2 I/cm /day.
-overlying-
2. Sand: light red brown; medium- to coarse-grained;
2
permeability ranges from 1.2 to 4 I/cm /day;
thickness unknown but estimated at maximum of
46 m.
Stephenson (1971) indicated that these layers likely overlaid a
crystalline bedrock composed of granite-like Precambrian rocks.
Table 1 presents representative grain size characteristics
for selected and representative samples taken at or near the
water table elevation within three of the wells. The predominant
sand grain size at or near the water table was within the medium
grain range, 0.25 to 0.5 mm diameter. The water table occurred
in either of the two vertical soil zones described, depending on
the location within the development area. According to Huff and
Stephenson (1971) the water table was generally within the upper,
finer-grained soil east of Shoal and Cadotte Lakes and within the
lower, coarser-grained sands west of that position. They attrib-
uted this to the coincidence of the mean water table level in the
Shoal and Cadotte Lakes are (299-300 m elevation) with the
average elevation of the fine/coarse-grained sand boundary (299_
1.5 m elevation),
-------
TABLE 1
SIEVE ANALYSES ON SELECTED SAMPLES-VOYAGER VILLAGE,
BURNETT COUNTY
Sieve
10
16
40
60
80
<80
mesh
mesh
mesh
mesh
mesh
mesh
Size
(2
(1
(0
(0
(0
(0
mm)*
.2 mm)
.42 mm)
.25 mm)
.15 mm)
.15 mm)
TOTALS
Well
Weight
gms
28
228
820
788
185
96
2145
No.
2
Percent
Total
1
10
38
36
8
4
100
.31
.63
.29
.74
.62
.48
.07
Well No.
We ight
gms
27
219
1240
379
153
101
2119
3
Percent
Total
1
10
58
17
7
4
100
.27
.34
.52
.89
.22
.77
.01
Well No. 6
We ight
gms
__
0.5
17
375
489
179
1061
Percent
Total
_—
0.05
1.60
35.34
46.09
16.87
99.95
*Wentworth Scale for sand:
very coarse-grained
coarse-grained
medium-grained
fine-grained
very fine-grained
Dash (—) indicates no contribution made from that fraction.
1.0 - 2.0 mm
0.5 - 1.0 mm
0.25 -0.5 mm
0.125 - 0.25 mm
0.0625 - 0.125 mm
25
-------
Stephenson (1971) noted a soil composition change which oc-
curred along the approximate line A-A' shown in Figure 1. North-
east of this line, soils were sandy as previously described. To
the southwest, the soil matrix was siltier; however, gravel per-
centages were found to increase. Gravel was scarce over much of
the northeastern area. According to Stephenson, there appeared to
have been a relationship between the soil differences and dif-
ferences in surface water character; Bartash Lake had soft water
and was non-calcareous. The surface waters to the northeast ap-
peared to be hard waters.
SORPTION TESTS
The results of phosphate sorption tests run on the soils of
the study area are presented in Table 2. Examination of this
data shows that the various samples sorbed from 1 to 5 mg.P/100 g
soil in 24 hours. This amount of sorption is small when compared
to what would be expected in typical clay soils. Various clay
mineral soils have been found to sorb, at neutral pH, from 0.03
to 0.07 millimoles phosphorus per gram solid (93 to 217 mg P/100 g
solid) at equilibrium (Grim, 1953). Although the behavior
of various types of natural soils from other areas under the par-
ticular test conditions used was not generally known, the results
of the Voyager Village development area soil tests tended to show low
short-term sorption capacity. However, tests of this type do not
adequately measure long-term sorption and precipitation such as
that associated with hydroxyapatite formation. Comparison of the
sorption values with the sorption maxima reported in Tofflemire
et al. (1973) and Ellis and Erickson (1969a) shows that the amounts
of P sorbed by these samples (1 to 5 mg P/100 g) were at the lower
end of the range of maximum sorption reported in the literature
(2 to 49 mg P/100 g). If higher concentrations had been incor-
porated in this testing, it is likely that greater sorption capac-
ity would have been found.
26
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TABLE 2
PHOSPHATE SORPTION TESTS ON THE
VOYAGER VILLAGE DEVELOPMENT AREA SOIL
(sorption time - 24 hours)
Well Number*
6
6
9
9
17
17
18
18
24
24
38
38
mg P/100 g solid
2.2
1.2
4.0
4.3
3.4
1.9
4.0
3.1
2.8
2.1
3.4
5.0
*Numbers do not necessarily correspond to well
numbers.
Samples provided by Owen Ayres 6 Associates.
27
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HYDROLOGY AND WATER QUALITY
Available water table and surface water elevations for Octo-
ber, 1970 as presented by Stephenson (1971) are shown in Figure 3
and indicate that the groundwater in the Voyager Village develop-
ment area moved from the southeast to the northwest. According to
Stephenson (1971) surface water movement was also in this direc-
tion, toward the St. Croix River. Estimated permeability values
in the sand layers at the wells averaged from 1.2 to 2.4 I/cm /day
(Huff and Stephenson, 1971). The recharge for the development
area groundwater appeared to be southeast of Birch Island Lake.
Drainage systems in recently glaciated regions are not always
well developed. As a result, according to Huff and Stephenson
(1971), perched and/or otherwise isolated surface water bodies are
not uncommon. The unnamed lake to the west of well 13 appeared to
be perched 7.6 to 9.1 m above the water table. Huff and Stephenson
noted that this fact may account for its apparently more advanced
eutrophic state relative to other area lakes.
In general, groundwater in the development area was found to
move in a simple flow pattern. The surface topography of the
area apparently had no influence on the direction of groundwater
movement. According to Huff and Stephenson (1971), this appeared
to be true both for the different.seasons and for different con-
ditions. For most, if not all lakes within the Voyager Village
development boundaries, groundwater entered lakes from the east
and southeast perimeter and re-entered the groundwater system along
the west and northwest perimeters of the lakes.
Groundwater Velocity
As discussed by Stephenson (1971), the water table gradient
for that portion of the development area between Birch Island and
Shoal-Cadotte Lakes would be one m per 1000 m. An estimate of
groundwater flow volume per m width of flow path in 46 m of soil
was between 242 and 2019 I/day. The 242 I/day estimate was for
the development between Birch Island and Shoal-Cadotte Lakes.
Groundwater velocities were calculated to range from 0.15 to
28
-------
Figure 3
Groundwater Flow Pattern
Voyager Village Development Site
Water Table Elevations on October 17 and 21,1970
Lake Surface Elevations on October 3,1970
(Elevations in Feet Above Mean Sea Level)
Scale: (cm * 0.6km
975
980.
_ 983* x
: 983 985
984
987
985
BIRCH ISLAND
LAKE
985
After Stephenson (1971).
Note: The units in this figure were taken from the
original report (Stephenson, 1971).
29
-------
1.2 m/day. In the area of immediate interest where the septic tank
study was conducted, a velocity of about 0.3 m/day appeared to be
average.
Groundwater Quality
The 21 wells were sampled once in July, 1970. The values of
the various physical and chemical parameters measured are presented
in Table 3. The pH of the various groundwater samples ranged from
6.4 to 7.6. pH values in this order of magnitude are normally
found in groundwaters and would not cause any water quality prob-
lems.
Specific conductance values ranged from 64 to 440 umhos/cm
at 21°C. The majority of the wells had specific conductance values
between 100 to 200 ymhos/cm. Specific conductance is a measure of
the total amounts of salts in solution. The contamination of
groundwaters by septic tank effluents will be expected to increase
the total amounts of salts considerably above the levels found in
the wells sampled. The high value of 440 for well number 1 is
somewhat surprising since wells 2, 3,-4, 7 and 8 are located
in the same general area and all show values which are more in
accord with what is expected. The examination of well 1 data
shows that the calcium and alkalinity are also high for this well,
while the chloride is about the same as in the other wells. The
sodium is higher for this well than the others. It appears that
this well is in an area where the groundwater has had the oppor-
tunity to pick up significant amounts of calcium and carbonate
species from the detrital limestone in the region.
Generally, turbidity values in groundwaters are low and fre-
quently zero due to the filtration of the particulate matter by
the aquifer material. The high turbidity values noted in some of
the wells resulted from the large amounts of suspended solids
which arose from the recent placement of the well points in the
area. In order to make a more realistic assessment of the tur-
bidity levels in the water, it would be necessary to pump each of
these wells for a considerable period of time. This would tend
to clear up and eliminate the debris that is left in the well
30
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TABLE 3
CHEMICAL ANALYSIS OF THE HELL POINT SAMPLES FROM VOYAGER VILLAGE PROJECT
COLLECTED III JULY, 1970 BY D.A. STEPHENSON
CO
Parameter*
pH
Specific
Conductance
limhos/CM
at 21»C
Turbidity
(JTU)
Na*
Ca**
HO~-N
N1I*-H
Total P
Soluble
ortho P«
Cl~
Fe'soluble"**
Fe total
Alkalinity
1
2
3
7.5 6.G 7.5
mo 101 251
5
12
15.5
50.0
0.7
0.15
0.1
0.007
3.0
0.03
0.05
168
0
1.6
2.5
5.5
0.15
0.15
0.31
0.006
2.5
0.16
0.21
38
11
1.0
6.5
23.0
0.30
0.60
0.08
0.003
12.5
0.01
0.2J
115
M
S
6
WELL POINT NUMBED
7 8 10 11A*"
61 113 265 111 120
19
1.5
2.5
3.0
0.15
0.21
0.06
0.001
2.5
0.07
6.12
29
0
2.0
6.0
7.0
0.08
0.11
0.02
0.001
2.5
0.03
2.63
59
10
5.1
6.5
16.0
0.60
0.02
0.16
0.005
13. S
0.03
0.17
99
11
3,3
5.S
12. S
0.15
0.50
0.13
0.005
5.0
0.03
0.03
70
0
2.3
5.0
7.0
0.07
0.01
0.30
0.001
5.0
0.03
0.82
15
91
17
1.7
1,0
8.0
0.08 1.10
0.03 0.06
0.20 0.12
0.006 0.08
2.0
0.11 0.03
0.98
*5
11B
6.9
118
3.1
8.0
0.17
0.09
0.01
5.5
0.08
15.1
£2
13
97
17
3.0
5.0
0.70
0.12
O.OU
3.0
O.H
5.0
»
11
66
0
2.5
1.0
1.6
0.11
0.16
0.005
3.5
<0.01
1.25
18
IE
18
95 220
15
3.0
5.0
I/O
0.10
0.36
0.001
1.0
0.03
1.10
33
0
7.0
19.0
0.45
0.06
0.77
0.001
15.5
0.07
1.K1
82
19
20
220 110
0
15.5
m.o
0.10
o.os
0.013
2.0
0,03
0.3
178
8
3.5
10,0
0.15
0,12
0.21
0.001
1.0
0.13
0.23
52
21
6.7
97
17
3.0
5.0
1.0
0.30
0.58
0.005
1,5
0.07
2.16
3M
*A11 values reported as «g/l except pH, Specific Conductance and turbidity.
**Soluble defined as passage through O.MS u pore size Membrane filter.
***Insufficient sample collected for complete analysis.
Many of the samples collected contained large amounts of suspended solids that arose from
the drilling of the well points. These turbidity, total iron and total phosphate values
are expected to be much larger than normally found in groundwaters as a result of this
contaminat ion.
-------
immediately after placement. No attempt should be made to judge
any change in water quality based on changes in turbidity from
those reported at this sampling.
The sodium values ranged from 1.5 mg/1 to about 12 mg/1 with
the typical values on the order of 2 to 5 mg/1. These values are
normal for groundwaters of the area. The 1970 levels of sodium in
the groundwater do not represent any adverse effect on water qual-
ity. It would be expected that large increases in the amount of
sodium in the groundwaters would occur as a result of the contami-
nation of the aquifer by septic tank effluent.
The magnesium values ranged from 2.5 to 15.5 mg/1. These
values indicate that, in general, the aquifer material has a low
limestone content and the waters derived from it would be classi-
fied as soft waters.
The calcium values ranged from 3 to 50 mg/1. The majority of
the values ranged from 3 to 15 mg/1. The only exceptions to these
values were well numbers 1 and 19. The high values at well num-
bers 1 and 19 indicate that these wells are in small pockets of
calcareous material. This observation is supported by the fact
that these two stations have relatively high alkalinities which
indicate that the high calcium arises from the dissolution of
calcium carbonate in the aquifer.
Nitrate derived from ammonium is one of the constituents of
septic tank effluent which affects groundwaters. All of the ni-
trate values for the wells sampled were less than 2 mg/1 nitrate-
N. Concentrations of this magnitude are typically found in ground-
waters. Concentrations of 10 mg/1 N are considered to be exces-
sive and would cause the water to be rejected for water supply
purposes. However, in-lake concentrations in excess of approxi-
mately 0.3 mg/1 nitrate-N are of concern and would tend to produce
excessive growths of algae and aquatic plants in the lake if
other constituents necessary for growth were present in adequate
amounts. Septic tank effluent will likely lead to increased con-
centrations of nitrate in groundwaters. This could further ag-
gravate the problems caused by excessive fertilization of lakes
32
-------
if the septic tank effluent flowed through the groundwater into
the lakes, and if the lake system is nitrogen limited. Fortunately,
there are a number of chemical and biochemical reactions that tend
to reduce nitrate concentrations in some groundwaters. These re-
actions will tend to minimize the nitrate problems in some areas.
However, the understanding of these reactions is such that it is
impossible to predict without extensive study whether or not ni-
trate may be a problem as a result of contamination of groundwaters
by septic tank effluent. It appears from Table U that a compari-
son of available nitrogen and phosphorus concentrations shows
that nitrogen may be the limiting nutrient in at least some of
the area lakes. Therefore, groundwater nitrate may be a problem
in influencing algal growth in surface waters.
Generally, groundwaters have very low concentrations of am-
monium since this chemical species tends to be sorbed onto soil
particles. As indicated by ammonium concentrations in excess of
0.1 mg/1 N, the aquifer materials of this area likely have a low
sorption capacity for ammonium. The concentrations found in these
wells would generally present no significant water quality prob-
lems for domestic use. However, when ammonium concentrations in
groundwater discharging into a lake are greater than 0.3 mg/1 N,
a potential for increasing the fertility of the lake exists since
ammonium in addition to nitrate is readily available for algal
growth.
The total phosphorus concentrations found in these wells are
not generally characteristic of the groundwaters since they rep-
resent the phosphorus associated with the high turbidity (sus-
pended solids) which resulted from the recent placement of the
wells relative to the well sampling. Normally, one would expect
to find little total phosphorus in the aquifer and any phosphorus
that is found would probably be in a soluble orthophosphate form.
Nearly all the values for soluble orthophosphate are less
than the critical levels of 0.01 mg P/l that have frequently been
found to cause excessive growths of algae and other waterweeds in
lakes. The one exception was well 11A which had been found to
33
-------
TABLE 4
CHEMICAL ANALYSIS OF SURFACE WATERS IN
VOYAGER VILLAGE DEVELOPMENT AREA
(June 9, 1970)
Bartash
Parameter Lake
Specific
Conductance
Vmhos/cm @ 22°C
pH
NH^-N
NO^-N
Organic-N
Soluble ortho P*
Total P
Aklalinity as
CaC03
26
7.2
0.04
< 0.02
0.52
0.006
0.032
2.2
LOCATION
Outlet Little Culbertson
Loon Bear Creek-Spring
Lake Lake Outlet
110
8.8
0.04
0.04
0.36
0.086
0.364
50.0
100
8,2
0.04
0.04
0.55
0,143
0.556
48.0
148
9.1
0.02
0.06
0.3
0.098
0.408
74.3
Loon Creek
at Loon
Creek Trail
147
8.1
0.06
0.06
1.1
0.264
0.574
54.5
^Soluble is defined by passage through a 0.45 y pore size membrane
filter.
All values reported as mg/1 except Specific Conductance and pH,
34
-------
contain 0.08 mg P/l soluble orthophosphate. It is likely that
this sample was contaminated as it contained large amounts of sus-
pended solids and there was insufficient liquid available to per-
form the complete set of analyses on it. Based on the previous
studies conducted on the sorption capacity of the aquifer mate-
rials from this area, it is reasonable to conclude that .surface-
water contamination problems could result from the use of septic
tank wastewater disposal systems in this area, provided that the
contaminated groundwaters reach a lake or stream. Normally, phos-
phate is not transported to any degree in aquifers which are high
in calcium carbonate, due to the interaction of the phosphate
with the calcium. Therefore, in the areas where high alkalinity
and hardness were noted, lesser phosphate transport will be ex-
pected.
The chloride levels found in the various wells ranged from
2 to 15.5 mg/1. These levels would not cause any water quality
problems. The discharge of septic tank effluents to groundwaters
will result in a large increase in the chloride content of these
waters. Chloride is one of the chemical parameters that is a
useful indicator of the contamination of groundwaters by septic
tank effluents.
The total iron represents the iron that is primarilv from the
contamination of some of the water samples by the well point driving
operations. The soluble iron represents that iron that would pass
through a 0.45 micron pore size filter and is probably, in this
case, iron that is in a very finely divided particulate form. The
iron present may aid in the removal of phosphorus from the ef-
fluents .
The alkalinity values ranged from about 30 to 180 mg/1 as
calcium carbonate. The alkalinity values parallel the calcium
and magnesium values. The high alkalinity values reflect the fact
that some parts of the aquifer are somewhat calcareous.
From an overall point of view, the groundwaters in the Voyager
Village development area were of high quality at the onset of the
study.
35
-------
Surface Water Quality
In order to assess general surface water quality in the Voy-
ager Village development area before development, grab samples
of water were collected from the lakes and streams in the area.
The values of general physical and chemical parameters measured
in the surface waters are presented in Table M-. At the time of
year that samples were collected, relatively low concentrations
of nitrate, ammonium and soluble orthophosphate will likely be
present in surface waters as a result of uptake by aquatic plants.
Consideration, therefore, must be given to the total phosphorus
and organic nitrogen concentrations. These values reflect to a
degree the amounts of potentially available nutrients present
within algal cells which would become available upon the death
of the plants.
Bartash Lake is a soft water, seepage lake of high water
quality. It had a very low specific conductance of 26 ymhos/cm
@ 22°C. The alkalinity in this lake was 2.2 mg/1 as CaCO~. The
O
aquatic plant nutrient concentrations found on the date of sam-
pling were generally low. The only well drilled near Bartash
Lake is number 21. Comparison of the water quality between this
well (Table 3) and the lake shows that there was little relation-
ship between the two. Water taken from well 21 had a much greater
alkalinity and greater specific conductance than that of the lake.
Loon Lake is a hardwater seepage lake adjoining Cadotte Lake.
The north end of the lake on the date of sampling had thick
aquatic vegetation and a few areas of floating bog. Based on the
high pH and high total P concentration, it would appear that on
the date of sampling, this was a highly productive lake. The
wells located near Cadotte and Loon Lakes (Table 3) had alka-
linity and specific conductance values which were similar to, al-
though not the same as, the lake water.
Little Bear Lake is a hardwater seepage lake containing high
concentrations of phosphorus and a relatively high organic N con-
centration. This would indicate a fertile water body. Well 20,
located on the north side of the lake, had a general chemical com-
36
-------
position similar to that of the lake. This would be expected
since this well was in the general direction of groundwater flow.
Culbertson Creek appeared to be a hardwater stream contain-
ing relatively high concentrations of aquatic plant nutrients.
Wells 13 and 19 in the Culbertson Creek area had respectively low-
er and higher specific conductance and alkalinity than the creek.
Look Creek at Look Creek Trail is a hardwater stream containing
the highest concentrations of both nitrogen and phosphorus com-
pounds of the lakes and streams sampled.
From an overall point of view, except for Bartash Lake, all
of the other lakes and streams in the development area seemed to
be experiencing excessive aquatic plant fertilization in the ab-
sence of any development in the area.
37
-------
SECTION 5
RESULTS
SEPTIC TANK USE
The septic tank-tile field wastewater disposal system moni-
tored for this part of the study went into operation on May 20,
1971 serving a middle-aged couple. This couple resided on the
property for nine months each year during the spring, summer and
fall. They used an automatic washer with cold water All detergent.
There was no garbage disposal in use, but a dishwasher was instal-
led in May, 1973 (Carlson, 1973).
OBSERVATION WELL MONITORING
The first water samples were collected from wells A-M (see
Figure 2) on February 3, 1972. The results of the analyses made
on these samples are presented in Table 5. Slightly higher
chloride values were found at several wells (I, J, L, M), but not
at wells immediately down groundwater gradient from the tile
field. This pattern appeared to be related both to the fact
that the residence was not occupied during the winter months and
that the septic tank had been installed only eight months prior
to sampling. Of the four wells that showed elevated Cl" concen-
trations, two of them were the deeper wells. Higher calcium
concentrations were found in the deeper wells and could generally
be related to higher alkalinity values there. In these measure-
ments, as well as subsequent measurements, elevated concentrations
of alkalinity and, in many cases, calcium were observed in wells
directly down groundwater gradient from the tile field. In some
instances, such as on the February 3 sampling, and in some subse-
quent samplings, the increased alkalinity and calcium were not
accompanied by an increase in chloride. However, increases in
38
-------
CD
TABLE 5
VOYAGER VILLAGE SEPTIC TANK MONITORING STUDY OBSERVATION WELL DATA
(February 3, 1972)
Parameter
Specific
Conductance
Umhos/crn @ 20°C
PH
11*
Ca"
Mg+t
Alkalinity
as CaCO,
so;
Soluble ortho P
Total P
U
NO~-N
Organic N-N
A
48
6.2
0.5
1.3
0.5
4.7
1.8
13.8
13.0
0.011
0.13
0.065
<0.05
0.20
B
55
6.5
0.5
1.4
0.5
5.0
1.7
18,8
12.0
0.017
0.067
<0.05
0.10
C
59
6.7
0.5
1.4
0,5
4.7
0,5
21 .4
13.0
0.016
0.058
<0.05
0.12
D
47
6.7
0.5
1.2
0.5
4.8
2.2
14.0
13.7
0.015
0.088
<0.05
0.20
WELL POINT
E F G
45
6.8
0.5
1.2
0.7
5.0
2,0
14.6
15.0
0.013
0.23
<0.05
0.23
60
6.8
0.5
2.1
0.6
7.5
1.4
21.3
13,4
0.015
0.17
<0.05
0.23
48.5
6.6
0.5
1.2
0.5
4.6
3,4
11.7
15.0
0.013
0.11
0.059
<0.05
0.09
H
48.5
6.7
0.5
1.2
0.6
4.9
2.3
14.1
12.7
0,017
0,16
<0.05
<0.05
0.12
I
53
6.8
1.1
1.6
0.5
6.2
2.3
18.1
16.4
0.021
0.18
0.054
<0.05
0.20
J
40
6.6
1.4
0.9
0.5
4.6
3.2
10.3
14.7
0.013
0.36
<0.05
0.09
K
54
6.8
0.5
1.2
0.6
6.1
2.6
18.0
11.0
0.009
0.077
<0.05
0.08
L
68
6.8
1.1
1.2
0.7
8.5
2.9
27.6
8.3
0.014
0.049
<0.05
0.10
M
56
6.9
1.1
1.4
0.6
6.8
2.5
20.6
12.2
0.019
0.13
0.05
<0.05
0.23
All values rag/1 unless otherwise stated.
Dash (—) indicates analysis not made.
-------
specific conductance were noted. It appears that the septic
tank effluent was causing dissolution of calcium carbonate or
contained elevated calcium and bicarbonate concentrations. The
soluble orthophosphate concentrations were about the same both
up and down groundwater gradient from the tile field as were con-
centrations of ammonium and nitrate. Neither total P nor organic
N concentrations showed evidence of contributions from septic
tank effluent. The concentrations immediately down groundwater
gradient from the tile field were slightly lower than those up-
gradient.
The observation wells were sampled February 16, 1972, two
weeks after the first sampling. The data are presented in Table 6.
In general, the pH values were somewhat lower and the soluble
ortho P values were consistently three to five times lower
than those values found during the previous sampling. The
specific conductance, sodium and alkalinity values showed
that septic tank effluent had migrated as far as well F. The
calcium concentration was greater in the deeper wells than
in many of the more shallow ones and roughly corresponded to
the alkalinity values which were generally greatest in the
deeper wells. None of the available forms of aquatic plant
nutrients (soluble ortho P, nitrate, ammonium), total P or
organic N showed an increase in concentration down groundwater
gradient from the septic tank tile field. Organic N values were
all slightly lower down groundwater gradient from the tile field
than upgradient.
Table 7 presents data from the well sampling on April 17,
1972, two months after the previous sampling. The specific con-
ductance values appeared to be somewhat greater down groundwater
gradient from the tile field than the value upgradient. The
greatest specific conductance values were found in the deeper
wells and indicated the possibility of effluent movement in the
groundwater. The pH values were generally one unit above what
they had been at the last sampling. The calcium concentrations
appeared to be highest in the wells directly down groundwater
40
-------
TABLE 6
VOYAGER VILLAGE SEPTIC TANK MONITORING STUDY OBSERVATION WELL DATA
(February 16, 1972)
Parameter
Specific
Conductance
ymhos/cm @ 20°C
PH
Cl~
Na+
K+
Ca4*
Mg4*
Alkalinity as
CaC03
so;
Soluble ortho P
Total P
NHJj-N
NO~-N
Organic N-N
A
52
6.2
2.3
1.2
1.1
1.8
2.8
13.5
12
0.005
0.02
0.01
<0.05
0.21
B
55
6.2
2.3
2.1
0.8
6.9
0.7
18.0
10
0.001
0.019
0.06
<0.05
0.09
C
63
6.2
2.3
2.1
0.8
5.9
3.2
22.5
10
0.001
0.019
0.05
<0.05
0.16
D
50
6.0
1.8
1.8
0.2
1.5
2.8
15.0
10
0.005
0.031
0.08
<0.05
0.10
E
15
6.0
1.8
1.1
0.6
1.5
2.1
13.5
9
0.001
0.016
<0.05
0.12
WELL POINT
F G H
73
6.2
1.2
2.2
1.1
10. 1
1.1
21.0
9
0.006
0.061
0.08
<0.05
0.20
58
6.1
0.6
1.8
0.8
5.1
1.1
15.0
18
0.001
0.062
0.05
<0.05
0.16
10
6.3
1.8
1.5
0.8
3.7
2.2
13.5
7
0.001
0.021
0.01
<0.05
0.18
I
56
6.0
1.8
2.3
0.2
5.2
3.6
13.5
10
0.006
0.079
0.08
<0.05
0.09
J
39
6.1
1.2
2.1
0.1
3.1
2.1
10.5
9
0.001
0.025
0.06
<0.05
0.12
K
56
6.1
2.3
1.9
0.8
5.8
3.2
28.5
9
0.001
0.016
0.01
<0.05
0.16
L
73
6.6
1.8
2.0
0.8
9.2
2.8
31.5
8
0.008
0.012
0.06
<0.05
0.16
M
55
6.3
1.8
2.1
0.9
6.0
2.3
21.0
8
0.007
0.011
0.01
<0.05
0.18
All values rag/1 unless otherwise stated.
Dash (—) indicates no analysis made.
-------
TABLE 7
VOYAGER VILLAGE SEPTIC TANK MONITORING STUDY OBSERVATION WELL DATA
(April 17, 1972)
Parameter
Specific
Conductance
Vimhos/cm @ 20°C
PH
Cl~
Na+
Kf
Ca"
Mg+ +
Alkalinity
as CaCO-
S0=
Soluble ortho P
Total P
NH*-N
NO--N
A
52
7.4
1.9
2.1
0.5
5.6
2.2
15
11.1
0.008
0.09
0.23
0.12
B
69
7.6
1.9
2.0
0.4
6.6
1.7
51
10.9
0.006
0.08
0.16
0.1
C
69
7.5
1.9
2.0
0.4
7.7
2.2
27
8.3
0.006
0,08
0.12
0.07
D
60
7.4
1.9
1,8
0.4
6.5
2.7
16
11.1
0.009
0.09
0.16
0.11
E
50
7.4
1.9
1.5
0.4
5.2
3.0
18
9.3
0.003
0.05
0.14
0.10
WELL POINT
F G H
74
8.2
1.9
2.4
0.4
6.5
3.5
21
9.1
0.009
0.17
0.13
0.11
50
7.4
1.9
1,8
0.4
5.5
2.8
12
10.9
0.006
0.08
0.36
0.09
40
7.5
1.9
1,5
0.4
4.0
2.8
16
5.3
0.003
0.04
0.18
0.10
I
69
7.6
1.9
2.0
0.4
8.1
3.0
26
8.6
0.008
0.06
0.24
0.09
J
42
7.5
1.9
1,2
0.4
3.9
2.4
12
9.5
0.006
0.12
0.22
0.10
K
80
7.5
1.9
2,2
0.5
9.5
0.7
21
7.7
0.004
0.05
0.34
0.17
L
76
7.7
1.9
2.0
0.4
8.3
4.9
34
8.8
0.005
0.12
0.13
0.10
M
58
7.6
1.9
1.8
0.4
6.4
3.2
21
6.9
0.003
0.02
0.17
0.07
All values mg/1 unless otherwise stated.
-------
gradient from the tile field and also in the deeper wells (K and
L). None of the aquatic plant nutrients appeared to be trans-
ported from the septic tank effluent through the groundwater at
this sampling.
The data from samples collected on August 29, 1972 (Table 8),
indicate that septic tank effluent was moving in the direction
of estimated groundwater flow. The specific conductance, chlo-
ride, calcium, alkalinity and nitrate levels all appeared to be
greater at well points C and F, directly down groundwater gradient
from the septic tank tile field, than those at outlying or up-
gradient wells. Potassium concentrations varied between 2 and
5.4 mg/1 without an apparent pattern. The soluble orthophosphate,
total phosphorus and ammonium concentrations did not reflect ef-
fluent contamination, however. Those values at wells down ground-
water gradient from the tile field were generally the same or less
than values upgradient.
Table 9 presents the data from groundwater samples collected
on October 29, 1972. Since the fall of 1972 had been a particu-
larly wet period, the concentrations of some of the parameters
may be markedly different from those which would normally be en-
countered in shallow groundwater. The specific conductance and
alkalinity both showed evidence of effluent contamination of the
first tier of wells, the three deeper wells, and as far directly
down groundwater gradient as well points I and M. The soluble
orthophosphate concentrations were greater on this date than on
most of the previous dates. This could be related to the high
rainfall received that fall. The down groundwater gradient con-
centrations were, however, about the same or less than the con-
centration above the tile field. Total phosphorus, ammonium, and
nitrate from septic tank effluent did not appear to be contaminat-
ing the groundwater. The groundwater turbidity was high in sam-
ples from wells A and F, possibly indicating suspension of sedi-
ment in the well during sampling.
On January 25, 1973, wells A-M were sampled. Selected sam-
ples were analyzed for only selected constituents as presented
43
-------
TABLE 8
VOYAGER VILLAGE SEPTIC TANK MONITORING STUDY OBSERVATION WELL DATA
(August 29, 1972)
Parameter
Specific
Conductance
Umhos/cm @ 20°C
pH
Cl~
+
Na
++
Ca
++
Mg
Alkalinity
as CaCO,
1
Soluble ortho P
Total P
4
NH^-H
NOr -H
O
A
52
6.5
2.3
2.1
5.7
2.5
11.1
6.8
0.060
0.088
0.20
<0.05
B
10
5.7
1.6
2.1
15.0
3.5
21.2
11. 0
0.006
0.021
0.23
0.05
C
68
6
1
2
8
3
21
11
0
0
0
0
.8
.1
.2
.0
.0
.8
.2
.001
.013
.20
.13
D
56
6.9
1.5
2.0
5.7
1.1
17.1
8.5
0,003
0.016
0.17
<0.05
E
18
7.5
1.5
1.6
3.5
0.00
15.1'
10.5
0.005
0.020
0.26
0.06
WELL POINT
F G
61
7.0
2.7
2.3
8.5
1.1
23.2
11.5
0.005
0.022
0.31
0.09
51
6.6
2.8
1.9
5.3
1.1
11.0
11.0
0.003
0.021
0.20
0.06
H
11
6.7
1.8
1.6
1.0
0.8
15.0
5.8
0.001
0.022
0.11
0.06
I
57
7.5
3.3
2.2
6.3
0.1
17,8
11.7
0,008
0.056
0.20
0.17
J
12
7.0
1.8
2.0
8.2
1.8
30.0
7.8
0.002
0.011
0.30
0.06
K
60
7.0
2.1
1.9
8.2
1.9
22.8
7.5
0.002
0.011
0.16
<0.05
L
10
6.9
1.8
1.5
3.2
0.2
10.1
11.7
0.001
0.030
0.28
0.10
H
88
7.0
1.3
2.1
6.1
0.6
20.0
10.0
0.002
0.011
0.030
<0.05
All values mg/1 unless otherwise stated.
-------
TABLE 9
VOYAGER VILLAGE SEPTIC TANK MONITORING STUDY OBSERVATION WELL DATA
(October 29, 1972)
Parameter
Specific
Conductance
pmhos/cm @ 20°C
PH
Turbidity (NTU)
Cl~
Na +
K +
C-3+4
Mg+ +
Alkalinity
as CaCO~
so=
Soluble ortho P
Total P
NH^-N
NO--N
A
46
5.8
11.4
16.7
1.7
3.0
9.6
1.9
11.6
6.8
0.045
0.07
0.30
0.23
B
62
6.4
5.7
12.8
20.0
<0.5
7.4
2.4
22.0
4.8
C
130
6.5
2.7
20.8
2.6
<0.5
13.4
6.1
31.6
5.5
0.006 0.005
0.04
<0.05
<0.04
0.04
<0.05
<0.04
D
59
6.7
5.4
15.8
1.5
<0.5
5.6
2.4
15.4
5.4
0.041
0.08
<0.05
<0.04
WELL POINT
E F G
44
6.0
3.7
11.9
1.0
<0.5
5.4
1.3
13.5
5.0
0.020
0.04
<0.05
0.48
63
6.3
13.4
11.9
.1.9
<0.5
6.7
1.3
21.2
4.4
0.012
0.09
<0.05
0.17
53
6.7
1.9
12,1
1.2
<0.5
6.1
. 1.8
14.3
4.6
0.048
0.05
<0.05
<0.04
H
39
6.8
4.0
25.0
1.1
<0.5
4.0
1.3
21.2
2.6
0.038
0.05
<0.05
<0,04
I
56
6.8
3.7
14.1
2.0
<0.5
5.8
2.0
23.2
3.0
0.063
0.06
<0.05
<0.04
J
35
6.9
4.3
12.6
0.5
<0.5
3.8
1.1
13.5
3.4
0.036
0.06
<0.05
<0.04
K
66
6.9
4.3
17,3
1.6
<0.5
8.0
2,7
33.6
3.4
0.040
0.08
<0.05
L
70
7.0
2.0
14.9
1.7
<0.5
9.1
3.1
31.3
3.0
0.045
0.10
<0.05
<0.04
M
56
7.1
1.6
18.3
1.7
<0.5
11.2
2.2
21.6
3.0
0.060
0.06
<0.05
<0.04
All values mg/1 unless otherwise stated.
-------
in Table 10. The specific conductance values indicated the pre-
sence of septic tank effluent in the first tier of wells and at
least as far down groundwater gradient as wells F and L. Higher
chloride and nitrate concentrations were also found at well C,
but not beyond that point. There was no detectable movement of
soluble orthophosphate or ammonium from the effluent into the
groundwater at these wells.
The values of the parameters measured in the groundwater
samples collected on July 26, 1973, are presented in Table 11.
It appeared that most of the transport of effluent occurred down
the central groundwater flow line. Increased levels of chloride
and nitrate were found at well C; increased specific conductance
was found in the first tier of wells and as far down groundwater
gradient as well I. No transport of phosphorus was evidenced by
this sampling. As illustrated by the specific conductance, chlo-
ride and nitrate values, there appeared to be effluent movement
to the right of the central, down groundwater gradient line es-
tablished. Water from well D showed higher concentrations of
these constituents than did water from well B on the opposite side
of the center line of groundwater flow as estimated by Huff and
Stephenson (1971). The specific conductance value was even
slightly above background levels at well G, beyond well D. If
the direction of flow had changed from that originally estimated,
then additional transport may be occurring which would not have
been found at the wells monitored. Therefore, it was decided at
this point in the monitoring program to drill two additional wells,
N and 0, about 15 m northwest (perpendicular to estimated ground-
water flow direction) of wells G and D, respectively.
Table 12 presents data from the analyses of selected ground-
water samples collected on October 10, 1974. The specific con-
ductance, chloride, calcium, magnesium, nitrate and total kjeldahl
nitrogen values all indicated that the direction of the effluent
movement appeared to be toward well D as well as down the center
(estimated) groundwater flow line. This pattern had been sug-
gested by the data from the previous sampling 14 months earlier.
46
-------
TABLE 10
VOYAGER VILLAGE SEPTIC TANK MONITORING STUDY OBSERVATION WELL DATA
(January 25, 1973)
Well
Point
A
B
C
D
F
K
L
Specific
Conductance
ymhos/cm
at 20°C
53
74
96
69
75
75
74
pH
6.3
6.5
6.3
6.6
-
6.5
—
Ammonia
mg/1 N
< 0.1
< 0.1
< 0.1
< 0.1
-
< 0.1
—
Chloride
mg/1
0.7
< 1.0
3.0
0.8
0.9
0.5
0.7
Sodium
mg/1
1.4
1.6
1.8
1.4
2.1
1.4
1.7
Soluble ortho
phosphate
mg/1 P
< 0.003
< 0.003
< 0.003
< 0.003
0.003
< 0.003
< 0.010
Nitrate
mg/1 N
< 0.01
< 0.01
0.5
0.01
_
0.01
-
Dash (-) indicates no analysis made.
Samples were analyzed by WARF Institute, Inc., Madison, Wisconsin
-------
CO
TABLE 11
VOYAGER VILLAGE SEPTIC TANK MONITORING STUDY OBSERVATION WELL DATA
(July 26, 1973)
Well
Point
A
B
C
D
E
F
G
H
I
J
K
L
M
Specific
Conductance
ymhos/cm
at 20°C
48
71
94
89
53
84
64
45
68
42
65
72
54
Chloride
pH mg/1
6.0
6.1
6.7
6.8
6.2
6. 3
6.0
6.2
6.3
6.2
6.6
6.7
6.5
0.7
0.5
3.5
2,3
0.6
1.3
0.7
0.5
0.7
0.5
0,6
0.5
0.6
Sodium
mg/1
1.3
1.8
1.9
1.5
1.0
1.9
1.2
1.0
1.6
0.6
1,4
1.4
1.4
Soluble ortho
phosphate Nitrate
mg/1 P mg/1 N
< 0.01
< 0.01
< 0.01
< 0.01
< 0.01
< 0.01
< 0.01
< 0.01
< 0.01
< 0.01
< 0,01
< 0.01
< 0.01
< 0.02
< 0.02
0.81
0.11
< 0.02
0.11
< 0.02
< 0.02
< 0.02
< 0.02
< 0.02
< 0.02
< 0.02
Samples were analyzed by WARF Institute, Inc., Madison, Wisconsin
-------
-p
CO
TABLE 12
VOYAGER VILLAGE SEPTIC TANK MONITORING STUDY OBSERVATION WELL DATA
(October 10, 1974)
Parameter
Specific
Conductance
umhos/cm @ 20°C
pH
Cl~
Na*
f
K
Ca"
Mg"
Alkalinity
as CaC03
so=
Soluble ortho P
Total P
NO--N
Total Kjeldahl
Nitrogen
A
53
6.4
0.99
3.34
<10 <
5.10
1.58
15.4
10
0.004
0.008
0.22
0.03
B
73
6.5
1.14
3.64
ao
7.11
2.11
22,0
14
0.005
0.010
0.23
0.07
C
D
88 245
6.6
2.48
3.87
clO
9.32
2.86
30.8
10
0.005
0.012
<0.20
0,50
6.4
25.3
4.16
= 10
21.5
8.33
22,8
15
0.004
0.006
0.72
11.6
E
50
6.8
0.89
4.46
:10 <
<5.0
1,5
17,6
12
0.002
0.007
<0.20
0.07
WELL POINT
F G II
82
6,7
2.48
4.24
:10 <
7.61
2,23
26.4
10
0.003
0.010
<0.20
0.06
59
6.8
1.24
3.27
aO
5.56
1.67
15.4
12
0.003
0.008
<0.20
0.01
42
6.7
0.84
3.12
ao
<5.0
1.29
15.4
4
a. 006
0.027
0.20
0.01
I
70
6.8
1.74
3.19
aO
7.02
2.23
22.0
9
0.004
0.011
0.20
0.03
J
44
6.8
0.99
2.16
ao
<5.0
1.11
13.2
10
0.005
0.016
0.20
0.01
K
58
6.8
0.99
2.82
ao <
5.6
1.79
22,0
8
0.004
0.008
<0.20
0.01
N
52
6.8
0.99
2.71
:10 <
5.27
1.67
15.4
14
0.014
0.034
0.47
0.04
0
53
6.6
0.74
3.34
ao
5.23
1.91
17,6
20
0.019
0.032
0.41
0.03
All values mg/1 unless othewise stated.
Samples were analyzed by WARF Institute, Inc., Madison, Wisconsin
-------
The increased concentrations found at well D had not yet appeared
at wells beyond that point. However, specific conductance, chlo-
ride, calcium, and alkalinity values were above background levels
all the way down the central groundwater flow line to well I.
The total P and more significantly, the soluble ortho P concen-
trations showed that there had been no phosphate transport from
the septic tank tile field to the groundwater. The higher con-
centrations of both total and soluble ortho P found at the wells
N and 0 were possibly due to sample contamination resulting from
the newness of these well points. It is unlikely that they were
due to septic tank effluent contamination since concentrations at
wells D and G were low.
The last set of samples were collected at the septic tank
monitoring site on January 15, 1976, fifteen months after the
previous samples were collected. The values of selected para-
meters measured are presented in Table 13. The highest specific
conductance value was found at well D; the value was also high
at well G, beyond well D. The highest chloride and sodium con-
centrations were also found at well D. There was evidence of
chloride contamination beyond that point, at both wells G and N.
Elevated specific conductance and chloride values were found
along the central groundwater flow direction to well I. The
deeper wells along that path (K, L, and M), however, did not
show increased concentrations of chloride. The pH values of
wells B and E were considerably greater than the rest of the
wells sampled. Neither total phosphorus nor soluble orthophos-
phate concentrations showed evidence of phosphate transport in
the groundwater downgradient from this septic tank wastewater
disposal system.
50
-------
TABLE 13
VOYAGER VILLAGE SEPTIC TANK MONITORING STUDY OBSERVATION WELL DATA
(January 15, 1976)
en
M
Parameter
Specific
Conductance
umhos/cm @ 22°C
PH
Cl~
Na*
Soluble ortho P
Total P
A
65
7.7
0.8
2.0
0.005
0.32
B
35.5
9.2
0.2
0.8
0.008
0.26
C
73.5
7.8
1.6
2.2
0.008
0.31
D
195
7.8
33.0
3.4
0.008
0.25
E
39.5
9.3
0.3
0.9
0.006
0.18
F
82.5
7.8
2.8
2.2
0.01
0.28
G
81
7
6
2
0
0
WELL.
.6
.2
.0
.008
.14
POINT
H
41.2
7.1
0.6
1.4
0.008
0.30
I
79.8
7.7
3.0
2.1
0.009
0.30
J
45.5
7.5
0.5
1.1
0.006
0.36
K
6U. 5
7.7
0.6
1.7
0.01
0.28
L
85
7
0
1
0
0
,9
.6
.8
.011
.20
M
66
7.7
0.7
1.5
0.01
0.32
N
58
7.5
2.1
1U
0.009
0.38
0
' 9
7.5
0.8
l.M
0.009
0.32
All values mg/1 unless otherwise stated.
-------
SECTION 6
DISCUSSION
Examination of data for the four-year monitoring study shows
that septic tank effluent did migrate from the tile field into the
groundwaters of the region. This conclusion was based on the
data for conservative or essentially conservative chemical tracers
such as specific conductance and chloride, and other parameters
which may not be conservative. Data collected during this study
showed occasionally elevated nitrate and ammonium concentrations
in certain wells, but it did appear that there was appreciable
nitrogen removed in this aquifer system. No evidence for phos-
phate transport from septic tank effluent was found in any of
the monitoring wells, even though this was a sand aquifer with
a relatively high groundwater velocity. Except for the first
sampling, there appeared to be no seasonal effects on chemical
constituents at the monitoring wells which could be traced to
the nine month per year occupancy of the household.
The potential for adverse effects on surface water quality
resulting from groundwater transport of aquatic plant nutrients
!
from septic tank wastewater disposal system effluent is control-
led by a number of factors. When examining a functioning septic
tank wastewater disposal system to determine whether there is a
significant contribution to surface water of the phosphorus dis-
charged to the system from a household, it is necessary first to
define the groundwater hydrology of the region. Often, as was
found in the Voyager Village development area, there is no rela-
tionship between surface topography and direction of groundwater
flow. Far too often, it is assumed that the hydrology of ground-
waters surrounding a lake is such that the direction of the flow
is toward the lake. For many lakes, the groundwater flow is in
52
-------
on one side and out on the other. Those septic tank wastewater
disposal systems that are located on the down groundwater gradient
side of the lake do not contribute phosphorus or any materials to
that particular surface water.
The chemical characteristics both of the unsaturated zone be-
tween the tile field and the water table and of the aquifer ma-
terials determine to a large"extent whether or not aquatic plant
nutrients will be transported in the groundwater. Closely as-
sociated with this factor is the rate of groundwater flow and the
distance between a septic tank system and a water body of concern.
Soluble phosphate and ammonium can be sorbed by clay minerals.
In addition, phosphate can be sorbed by aluminum and iron oxides,
and other minerals in the soil. Phosphate sorption is usually
a rapid process, 80 to 90 percent complete in two to five days
(Tofflemire et al., 1973). The typically slow movement of ground-
water allows for precipitation of soluble phosphate with calcium.
The greater the distance the septic tank disposal system is from
a water body, the greater the potential for phosphorus removal
by the aquifer materials.
It is the chemical composition of the soils rather than grain
size characteristics which plays the dominant role in phosphorus
removal. Soils in the Voyager Village development area were
predominantly fine to medium sands. Even though septic tank ef-
fluent was readily measurable in observation wells 60 m downgradient
from the septic tank tile field monitored, the sandy aquifer ma-
terial exhibited complete phosphate removal during the course of
the four-year monitoring study.
It is possible that over a period of time, aquifer material
sorption sites will become saturated with phosphorus. However,
there is essentially infinite capacity for phosphorus removal due
to precipitation reactions. Indeed, some investigators have in-
dicated that the capacity for phosphorus removal may be independent
of prior exposure to phosphorus.
Another condition affecting potential significance of ground-
water transport of aquatic plant nutrients is that there must be
53
-------
actual recharging of the water body of interest by the ground-
water. Especially in glaciated regions, there can exist beneath
lakes an impervious clay layer which acts to separate the lake
from possible groundwater input. The groundwater then flows be-
neath or around the lake and no contributions of nutrients or
other contaminants to the lake can be made by the groundwater.
Some of these so-called perched lakes were found in the Voyager
Village development area.
An important factor that should be considered in making a
proper assessment of the significance of septic tank wastewater
disposal systems as a source of phosphorus for surface waters is
the proximity of the septic tank system to the water body of con-
cern with respect to excessive fertilization. For many water
bodies, any phosphorus transported from septic tank wastewater
disposal system effluent would be contributed to a lake or a stream
which is tributary to that water body. As discussed below, a sub-
stantial part of this phosphorus never reaches the downstream
water body in a form that is available to support algal growth.
For almost any lake, there would be on the order of 60. to 90 per-
cent retention of the annual phosphorus load within the lake sedi-
ments. This means that for the lake which is ringed by cottages
with septic tanks where either the septic tanks have failed or
where the subsoil system does not take up the phosphate, while the
phosphorus would contribute to the eutrophication problems within
the receiving water body, only a small fraction of the phosphorus
would actually be transported to downstream water bodies.
An example of this type of situation is the US-Canadian
Great Lakes. It would be expected that very little direct
phosphate transport due to the utilization of septic tank waste-
water disposal systems would be occurring from residences located
on the shores of the Great Lakes. Rather, these inputs are general-
ly made to a tributary lake or stream. Little of the P from septic
tanks located in the Great Lakes Basin would reach the Great Lakes
in an available form to thereby contribute to the excessive fer-
tilization of these water bodies. The basis for this conclusion
-------
is that a large part of the phosphorus present in streams and
rivers, especially during periods of high flow, frequently becomes
associated with particulate matter where the phosphorus is attached
to or becomes incorporated into clay. Further, as available P is
utilized in various biological processes, it is becoming less avail-
able for stimulation of algal growth since each time it is cycled
through a biotic system,some part of the phosphorus becomes re-
fractory. This thereby prevents it from stimulating algal growth.
Studies supported by the US EPA conducted by Lee and his graduate
students several years ago have shown that much of the particulate
phosphorus in several rivers is unavailable for algal growth (Cowen
and Lee, 1976). In general, it is likely that available nutrients
discharged to rivers which are considerable distances from the lake
of interest will have much less influence on stimulating extensive
fertilization problems than would the same nutrients discharged
directly to the water body.
If aquatic plant nutrients do enter a lake from the ground-
water, conditions existing in the lake could reduce their impact
on the water quality. For example, if groundwater recharge were
beneath an existing thermocline, such as may be present during
the summer growing season, added nutrients would remain trapped
in the hypolimnion. The interactions between the sediments in
the lake and the nutrients entering the lake via groundwater flow
would tend to convert both nitrogen and phosphorus to forms un-
available for stimulation of algal growth.
Another factor contributing to the overall significance to
surface water quality of aquatic plant nutrient transport from
septic tank effluent is the growth limiting element in the down-
gradient water body. If nitrogen is the limiting nutrient in the
water body of concern during the times of year of concern, as may
be the case in some of the Voyager Village development area lakes,
it is possible that additions of phosphorus to that water body
from the groundwater would have no effect on the surface water
quality.
55
-------
In assessing the overall impact on surface water quality of
available nutrient contributions from septic tank effluent, con-
sideration must be given to sources and magnitudes of other nu-
trient inputs to the water body such as urban and agricultural run-
off, point source inputs, atmospheric inputs, in addition to other
sources of nutrients in groundwater such as fertilizers or sani-
tary landfill leachate. It is possible that the contribution of
aquatic plant nutrients of septic tank effluent origin to a water
body would be insignificant when compared to other nutrient sources
which may be readily controllable.
From this and previous studies, it appears that, in general,
phosphate will not be transported from the septic tank wastewater
disposal systems to surface waters and thereby contribute to exces-
sive fertilization problems. However, it is conceivable that
there may be a very limited number of water bodies where septic
tank disposal systems are located immediately adjacent to a lake
and contribute sufficient phosphorus to the lake to stimulate ex-
cessive algal and/or macrophyte growth. Under these conditions,
consideration should be given to either construction of a sewerage
system to collect all wastewaters and provide adequate treatment
for phosphate removal or modification of the septic tank waste-
water disposal system to improve its phosphate retention capacity.
Based on previous, unpublished work by the authors, phosphorus
removal can be accomplished by the inclusion of limestone or
aluminum oxide in the septic tank wastewater disposal system tile
field or in a dike which is constructed below the soil surface
through which the wastewaters from the septic tank tile field
must pass en route to the nearby water course. Sikora ejb al.
(1976) demonstrated the effectiveness of an individual home
phosphorus removal system, using a vertical Plainfield sand col-
umn followed by a series of columns filled with calcite or dolo-
mite. The most effective of the systems tested was one in which
0.32 cm diameter calcite particles were used. It showed 99 per-
cent P removal during the first month but it decreased to 12
56
-------
percent in the sixth month of operation. Additional field evalua-
tion of this approach should be made under a variety of conditions
in order to determine the optimum design parameters to maximize
phosphate retention. This or similar approaches using aluminum
oxide is likely to be a cost-effective way to remove essentially
all of the phosphorus present in septic tank wastewater disposal
system effluent where there is potential for significant surface
water contamination.
57
-------
REFERENCES
American Public Health Association, American Water Works
Association, Water Pollution Control Federation, Standard
Methods for the Examination of Water and^Wastewater, 12th
Edition, American Public Health Association, New York.
(1965).
American Public Health Association, American Water Works
Association, Water Pollution Control Federation, Standard
Methods for the Examination of Water and Wastewater, 13th
Edition, American Public Health Association, New York.
(1971).
American Public Health Association, American Water Works
Association, Water Pollution Control Federation, Standard
Methods for the Examination of Water and Wastewater, mth
Edition, American Public Health Association, Washington,
D.C. (1976).
Beek, J., F.A.M. deHaan, and W.H. van Reimsdijk, "Phosphates
in Soils Treated with Sewage Water: I. General Information
on Sewage Farm, Soil and Treatment Results," J. Environ.
Qual. 6,:4-7 (1977a).
Beek, J., F.A.M deHaan,. and W.H. van Reimsdijk, "Phosphates
in Soils Treated with Sewage Water: II Fractionation of
Accumulated Phosphates," J. Environ. Qual, §:7-12 (1977b).
Blackman, R.R., L.M. Slather, and C.W. Threinen,"Surface Water
Resources of Burnett County," Wisconsin Conservation
Department, Madison (1966).
Boyle, W.C., and L.B. Polkowski, "Groundwater Quality Adjacent
to Septic Tank - Soil Absorption System," Dept. Nat.
Res., Madison, Wisconsin (1970).
Brandes, M., N.A. Chowdry and W.W. Cheng, "Experimental Study
on Removal of Pollutants from Domestic Sewage by Under-
drained Soil Filters," National Home Sewage Disposal.
Symposium, Am. Soc. Agric. Engr., Chicago, Illinois
(197U).
58
-------
Carlson, K.G, Persona,! Communication to G. Fred Lee, (July 5,
1973), ?
Childs, K.E., "Migration of Phosphorus Wastes in Ground Waters,"
Geological Survey Division, Mich. Dept. of Natural Resources
(May, 1974).
Corey, R.B., A.D. Hasler, G.F, Lee, F.H. Schraufnagel and T.L.
Wirth, "Excessive Water Fertilization," Report to Water Sub-
committee, Nat. Res. Comm, of State Agencies, Madison, Wis-
consin (1967).
Cowen, W.F. and G.F. Lee, "Algal Nutrient Availability and Limita-
tion in Lake Ontario During IFYGL, Part I, "Report to US EPA
Large Lakes Research Station, Grosse lie, Mich. (1976).
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Capacity of a Lake for Development Based on Lake Trophic
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59
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61
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
REPORT NO.
EPA-600/3-77-129
3. RECIPIENT'S ACCESSION-NO.
TITLE AND SUBTITLE
SEPTIC TANK. DISPOSAL SYSTEMS AS
PHOSPHORUS SOURCES FOR SURFACE WATERS
i. REPORT DATE
November 1977 issuina
6. PERFORMING ORGANIZATION CODE"
. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
Rebecca A. Jones and G. Fred Lee
. PERFORMING ORGANIZATION NAME AND ADDRESS
Institute for Environmental Sciences
The University of Texas at Dallas
Post Office Box 688
Richardson, Texas 75080
10. PROGRAM ELEMENT NO.
1BA609
11. CONTRACT/GRANT NO.
R-80U549
12. SPONSORING AGENCY NAME AND ADDRESS
Robert S. Kerr Environmental Research Lab,
Off ice., of Research, and Development
J.S. Environmental Protection Agency
Ada,. Oklahoma.74820
- Ada, OK
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
EPA/600/15
IB. SUPPLEMENTARY NOTES
16. ABSTRACT
A H-year groundwater monitoring study was conducted in the immediate
vicinity of an active septic tank wastewater disposal system in the sandj
stfbstrate in Burnett County of northwestern Wisconsin to determine the
potential for this method of wastewater disposal to contribute to excess: ve
fertilization of surface waters. To monitor the movement of the effluenl
and the character of the area groundwater, selected parameters were mea-
sured in water samples collected from an array of wells located up and
down groundwater gradient from the septic tank tile field.
During the course of this study, movement of septic tank effluent it
the groundwater was indicated by measured values of several of these param-
eters. However, there was no evidence of the transport of the phosphate
from septic tank effluent through the groundwater even at the monitoring
point closest to the tile field (about 15 m down groundwater gradient frc m
the tile field). The results of this study confirm the conclusions drawr
from similar studies in other areas reported in the literature, that pho£
phorus from septic tank wastewater disposal system effluent is u jually nc t
readily transported through the groundwater. Therefore, septic tank was- e
water disposal systems generally do not contribute significant amounts o:
phosphorus to surface waters to contribute to their excessive fertilization.
17.
KEY WORDS AND DOCUMENT ANALYSIS
a.
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
Septic Tanks
Phosphorus
Waste Disposal
Surface Waters
Ground Water
Phosphorus Migration
COSATI Field/Group
13/B
18. DISTRIBUTION STATEMENT
Release to Public.
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
72
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Perm 2220-1 (9-73)
62 '
#U.S. GOVERNMENT PRINTING OFFICE: 1S78-757-1W6617 Region No. 5-11
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