\lt
United States
Environmental Protection
Agency
Robert S. Kerr Environmental
Research Laboratory
Ada OK 74820
Research and Development
EPA-600/S2-83-026 May 1983
&EPA Project Summary
Design Principles for Wetland
Treatment Systems
David E. Hammer and Robert H. Kadlec
Published data pertaining to the
treatment of wastewater by wetland
irrigation have been assembled and
analyzed to begin identifying general
principles for the successful design of
wetland facilities. Sources of operating
data have been tabulated. Performance
is roughly correlated with overall sys-
tem features, but cannot be predicted
on the current basis. Existing com-
partmental models require more de-
tailed information than does or will
exist; thus a simplified compartment
model is presented.
Water quality is controlled by rapid
processes related to water movement,
mass transport to other compartments,
and consumption kinetics. Thus, wet-
land hydrology is fundamental to the
analysis of water quality improvement.
The ultimate fate of nutrients and con-
taminants is determined by sedimen-
tation, biomass production and har-
vest, soil and microbial processes.
Required wetland area depends on
effluent quality, ecosystem type and
age, and hydraulic regime. These ques-
tions can be addressed in terms of a
mass transport model for the zone of
rapid removal, and a "saturation" model
for the expansion of a zone of stabilized
activity about the discharge point.
Material balances, considering only
long-term consumption mechanisms
for nutrients and other pollutants, de-
termine the useful life and ultimate
performance of a wetland system.
Operational techniques and the use
of constructed wetlands are also con-
sidered. The economics of wetland
treatment are discussed.
This Project Summary was developed
by EPA's Robert S. Kerr Environmental
Research Laboratory, Ada. OK, to an-
nounce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
The treatment of wastewater by over-
land flow through a wetland is a new
concept Only in the last decade has the
performance of such systems become a
topic of scientific study. Wastewater dis-
charges to wetland areas are not a new
practice, for a number of sites have been
identified where discharge has been on-
going for more than half a century. New
treatment systems are being established
at natural wetlands and at wetlands specif-
ically constructed for this purpose. Signif-
icant improvements in wastewater quality
are generally observed, at a cost which is
low when compared to other alternatives.
The purpose of this study is to identify
data sources and to present certain design
concepts and their application to wetland
treatment
The reliable design of a wetland treat-
ment facility requires the development of
performance equations which describe
both the response of the ecosystem to
wastewater additions and the alteration of
water quality. These equations must be
developed from the operating data of
existing systems and from insight obtained
from research studies conducted in the
laboratory and at field sites. Since experi-
ence is somewhat limited, only the basic
features of the wetland treatment process
are susceptible to meaningful analysis.
These include wetland hydrology and
overland flow, removal rates for waste-
water components, and the effects of
nutrient additions on the continued ability
of a wetland to treat wastewater.
-------
When wastewater is discharged to the
surface of a wetland it flows away, spread-
ing into a dynamic mound about the dis-
charge. The depth which will result de-
pends upon the hydrological characteristics
of the wetland and impounding structures,
if any. Each wetland system has a hydraulic
capacity, which may change rapidly in
response to ram or other hydrological
factors. Depth limits will be determined by
the tolerance of wetland vegetation and by
consideration of operating factors such as
residence time. Depth and velocity will
also affect the ability of the wetland to
remove pollutants from the surface waters.
Hydrology of the wetland site is therefore
crucial to the understanding of the treat-
ment processes which occur.
The rate at which pollutant removal
occurs will determine the relationship be-
tween the wastewater inputs and the
quality of the wetland effluent These and
other parameters, such as removal effi-
ciency, are interrelated through a material
balance about the surface waters. There-
fore, the removal rate for each component
must be determined. These rates can vary
with factors such as water flow rate, depth,
season, species composition within the
wetland, type of soil substrate, and the age
of the treatment facility.
Prediction of removal rates, overtime, is
a primary task in the analysis of a wetland
treatment system design. Two approaches
to this problem are possible: the correla-
tion of operating data from existing sys-
tems; and the development of a concep-
tual model for the wetland treatment
system.
We have therefore reviewed data from
26 sites, as listed in Table 1. Based on
these, a model for the wetland treatment
system is proposed and analyzed in terms
of contributing processes.
Evaluation of a proposed system design
must ultimately turn to economics. The
available data on capital requirements and
operating expenses were therefore col-
lected and presented.
Wetland Hydrology
The design or evaluation of wetland
wastewater treatment systems requires a
sound understanding of the marsh hy-
drology. Surface water flow rates, soil
infiltration, and depth are of primary con-
cern. Water depths and flow rates are
usually determined by natural stream
flows, overland flow, precipitation, and
evapotranspiration. Introduction of waste-
water irrigation may result in localized
increases in water depths which in turn,
combined with increased nutrients, may
cause changes in the species composition
Table 1. Site Summary List.
Site
Bellaire, Ml
Bradford, ONT
Bri/lion, Wf
Brookhaven, NY
Clermont, FL
Cootes Paradise, ONT
Drummond, Wl
Dulac, LA
Gainesville, FL
Great Meadows, MA
Hamilton, NJ
Hay River, NWT
Houghton Lake, Ml
Humboldt, SASK
Jasper, FL
Kesalahti, Finland
Kincheloe, Ml
Lake Balaton, Hungary
Las Vegas, NV
Listowell, ONT
Mountain View Sanitary
District CA
Seymour, Wl
Suisun City, CA
Vermontville, Ml
Waldo, FL
Wildwood, FL
Approximate
Age, yr.
12
1
56
6
4
62
3
2
7
68
2
16
4
2
60
-
25
-
60
2
7
2
5
2
46
20
Annual
Discharge
106 gal.
30
0.5
98
3
4
-
15
0.03
6
1600
1.7
11
100
10
-
-
150
-
30,000
15
255
0.1
20
25
30
55
Data Base
Size
Small
Small
Medium
Small
Medium
Small
Small
Small
Large
Medium
Small
Small
Large
Small
-
-
Small
Small
Medium
Medium
Small
Small
Medium
Small
Small
Small
Identifying
Number
In Figure 1
2
-
4
-
-
10
-
-
-
6
-
1
3
-
-
-
-
•
•
-
9
-
-
•
8
7
of the plant and animal communities.
Removal of nitrogen, phosphorus, and
other pollutants is best accomplished by
slow overland flow of surface waters in a
thin sheet or by infiltration. Channelized
flow, characterized by greater water depths
and shorter residence times,tends to re-
duce the system's effectiveness for pollu-
tant removal.
In order to properly assess the per-
formance of a wetland, a complete water
budget must be prepared. All points of
influx and efflux must be identified and the
flows estimated throughout the year. Sim-
ilarly, precipitation and evapotranspiration
must be quantified. This water budget
combined with measurements of nutrient
concentrations can provide a complete
picture of the wetland treatment system
performance.
Correlation of Operating Data
Data from several wetland AWT sys-
tems allow calculation of the gross aver-
age removal rates of phosphorus and
nitrogen. While precise relations cannot
be established using these data from di-
verse systems, a trend of increasing re-
moval rate with increasing nutrient con-
centration is suggested. Plots of nutrient
removal rate versus nutrient loading rates,
as shown in Figure 1 for phosphorus,
define the operating limits which are ob-
served on existing systems, regardless of
hydrology, cover type, or climatic con-
siderations.
A Simplified Compartmental
Model
Improved design techniques require
consideration of individual phenomena
and processes within the wetland. A
larger body of reliable data is available on
the function of wetland subsystems than
on the performance of the wetland as a
whole. Relatively simple models of signifi-
cant ongoing processes make it possible
to obtain further insight into the overall
interactions between the wetland and ap-
plied wastewater. This procedure allows
the synthesis of a conceptual model,
which when represented in mathematical
terms, can be used to evaluate a new
design.
To facilitate the use of a model over long
periods of time (e.g., 20 to 50 years) a
simple, specialized structure is desirable,
as described in Figure 2. All transfers
between the surface waters and the sta-
tionary ecosystem are taken as the annual
net accumulation in each compartment. In
this way, cycling of nutrients and other
materials on seasonal, or even shorter
term, basis need not complicate the model.
Removal of dissolved nutrients
surface waters is controlled by
-------
Q10, Shallow (55)
• Total Dissolved Phosphorus
O Rate Based on Growing Season,
r * Thus is Likely High Relative
to Annual Average
O Total Phosphorus
I j Denotes Approx.
Age of Site
O 6, Shallow (69)
1(15)
3(1)
', Deep (55)
3d) 04(55)
7 V
'/
100 200 500
Phosphorus Loading (kg/ha/yr)
WOO
2000
Figure 1.
Effect of phosphorus loading upon removal rate. (See Table 1 for site identification
numbers.)
Wastewater
Additions
Natural
Water
Inputs
Water
Outputs'
Figure 2.
Wetland
Consumption
\ Processes
Biomass—Long- Term
Retention of
Nutrients and Other
Substances in the
Dynamic Biomass Pool
Soil & Sediments-
Solids Incorporated
into the Soil Column
Stationary Wetland Ecosystem
Simplified compartmental model for use in wetland treatment system design.
process. The process consists of delivery
and consumption. Consumption occurs
principally at the surfaces of the soil, litter,
plant stems and algal mat Delivery is
accomplished by convective mass transfer
^within surface waters, overland flow, or by
Hownward flow due to water infiltration.
"Consumption consists collectively of a
number of processes which initially are
relatively fast, but of which some slow
considerably as wastewater treatment
continues. Sorption will reach an equilib-
rium in the upper soil horizons reducing
the average areal uptake rate. Similarly,
biomass expansion, which offers a sink for
nutrients, will also reach a saturation con-
dition, where the release of nutrients due
to litter decay offset any uptake in new
growth. Woody biomass production al-
lows longer immobilization of nutrients
and constitutes a relatively permanent
removal mechanism. Soil production also
represents a long-term removal process
but is quite slow. While data are extremely
sparse, the same basic behavior can be
anticipated for heavy metals as well as
nutrients.
Two treatment regimes will exist in an
older wetland system as shown in Figure
3. In the vicinity of the wastewater dis-
charge a "saturated" region will exist
Here component removal rates will be
quite slow, comprised of the uptake rates
due to (1) sorption deep in the soil column,
(2) incorporation of material into new soil
and woody plants, and (3) microbial re-
lease of gases to the atmosphere. Outside
this"saturated" region, surface water con-
centrations of wastewater components
will drop exponentially with distance. In
this latter zone of rapid removal, it is the
transport of dissolved components through
the surface waters which limits the overall
rate. The amount of wetland area needed
for this zone of fast removal will be deter-
mined by mass transfer considerations
and for constant operating conditions
(depth, velocity, etc.) will not change. The
zone in the "saturated" regime will con-
tinue removal at a rate which is slower but
insensitive to modest changes in water
flow or depth. The expansion of this
saturated region continues until the total
affected area is sufficient to allow all
incoming wastewater components to be
removed by water infiltration, incorpora-
tion into new soil and woody biomass, or
release to the atmosphere. If the actual
wetland area is less than that required for
total retention of pollutants, breakthrough
will occur. In this case, only a portion of
the wastewater components fed to the
wetland will be retained and collection
efficiency will drop sharply.
Harvesting plant biomass is a direct
method of preventing saturation of the
biomass compartment. Nitrogen, phos-
phorus and other wastewater components
can be removed from the wetland system.
Higher removal rates can be maintained
indefinitely with limited area, using this
technique.
To employ this conceptual model in the
evaluation of wetland system designs, it
must be cast in mathematical terms.
The Mass Transfer Zone
When wastewater is caused to flow over
the surface of a wetland, nutrients and
-------
Zone of Rapid
Removal
"Saturated Zone"
Wastewater Discharge
Point
Unaffected Zone
Figure 3. Schematic of the zone of affected soil and biomass.
other polluants are removed, primarily by
delivery to and consumption at solid sur-
faces. At the wetland surfaces, sorption
and microbial processes may occur, as
well as plant uptake. Algal and duckweed
uptake may occur at the upper water
surface. These processes require that
each contaminant be transported to a
bounding channel surface.
A typical relationship to describe this
transport is:
N = kA (Cw - Cs)
where:
N = contaminant transport rate, gm/day
k = mass transfer coefficient, m/day
A = area of surface, m2
Cw = contaminant concentration in
water,gm/m3
Cs= contaminant concentration in water
at channel surface, gm/m3.
Such a rate expression must be
coupled with mass balances for the
contaminant and for the surface water to
predict the distance or time for the
removal of a dissolved substance.
The contaminant mass balance is, for
a linear-flow wetland
v0shd-Cw=-k0(Cw-Cs)-
dx
where:
Ce = the contaminant concentration in
evapotranspired water, gm/m3
Cp = the contaminant concentration in
precipitation, gm/m3
0 = flow porosity across the wetland
surface
0s = storage porosity
h = depth, m
t = time, days
x = distance, m
v = actual velocity, m/d
p = precipitation, m/d
e = evapotranspiration, m/d
i = infiltration, m/d
At some upstream point, x = 0, the con-
centration will be known. Presumably this
is either the discharge point; or, if the area
around the discharge is saturated, it will be
the outer edge of the slow removal zone.
For example, the zone of rapid removal
should begin near the discharge line for
denitrification (NOs' removal), since no
saturation can occur. For an "older"
facility, this rapid uptake zone for phos-
phorus would begin at a distance where
saturation ends.
This model may be easily solved in a
variety of special cases. It works well for
those sites where transect data are avail-
able with which to validate it The mass
transfer parameter, k, and the depth-velocity
relation are site specific.
The Loaded Zone
The addition of nutrients to a natural or
newly constructed wetland will cause a
zone of increased vegetative growth to
appear. This zone will expand with time
until either the permanent capacity of the
zone equals the loading rate or the loaded
zone reaches the boundaries of the wet-
land. The mathematical description of the
advance of such a loaded zone for each
substance of interest such as phosphorus,
consists of a mass balance on the zone and
the rates at which the substance is taken
up by the stationary ecosystem. These
uptake rates fall in three general cate-
gories. The first of these is a permanent
binding of the substance in question, or a
gaseous loss to the atmosphere, such as
denitrification. In these cases, a compo-
nent is permanently removed from surface
waters. A second general category con-
sists of an increase in the adsorbed quan-
tity of the substance, which is the physical
or chemical binding of the substance to
the soil substrate within the wetland. Such
processes are known to occur for phos-
phorus and ammonia, for example. The
third general category of nutrient con-
sumption is storage in an expanding bio-
mass compartment
Other uptake/release processes also
occur in the wetland ecosystem at rapid
rates. An example of this is the uptake of
phosphorus and nitrogen by algae. These
algae grow during the summer months,
die, and contribute a certain amount of
algal litter to the sediment layers within
the wetland. These algal sediments de-
compose and re-release the nitrogen and
phosphorus that was incorporated in the
biomass. This process is fairly rapid in the
summer months, and if one considers only
year-to-year variations in area, this process
is too fast to be noticeable. There is little
net effect of such rapid cycling. A second
type of rapid cycling of nutrients is the
uptake by vascular plants. With their
senesence and death, the leaching of
nitrogen, phosphorus and carbon from the
biomass directly back to the water column
occurs yearly. This cycle is also too fast to
be considered in a framework that is
geared to predicting the change of the
affected area from year to year. Thus, in
the model development which follows,
only those processes which persist for a
period greater than one growing season
are considered as long-term consumers
for nutrients. Put in another way, all
quantities are expressed as rates, but
these are averages over the period of one
year or longer.
To make this model more tractable, it is
assumed that sufficient residence time is
provided so that all material can reach the
plant and soil community. The zone of
mass transfer limitation of the removal
rate is neglected. This idealization results
in a sharp line of demarcation between the|
loaded and unloaded zones. This is not"
-------
entirely accurate since according to the
principles of mass transfer a zone must be
present in which nutrient levels within
surface water are decreasing.
In terms of the possible sinks, the mass
balance equation in words is:
addition rate = sorption rate +
permanent removal rate
+ temporary binding rate
+ discharge rate.
A variety of ways of expressing these
terms exists; one set of choices leads to
the following mass balance for the ex-
panding loaded zone:
where:
QC, = kyCi ^+ (rsCs + rA + rwXw +rHXH) A
Q = average annual wastewater addition
rate, rnVyr [380,000]
Cj = mass average concentration of con-
taminant or nutrient in influent waste-
water, gm/m3 [3.5]
A = area, m2
tr = time, yr
k = sorption equilibrium constant,
(gm/m3)s/(gm/m3)i[2.7]
Ci = average contaminant concentration
in surface water, gm/m3 [1.8]
y = average sorption depth, m [0.05]
rs = excess average annual soil accretion
rate, m/yr [0]
Cs = contaminant concentration in new
soil, gm/m3
TA = excess average annual rate of loss to
atmosphere, gm/m2/yr [2.1 ]
rw = excess average annual woody stem
accumulation rate, gm/m2/yr [0]
Xw = fraction contaminant in woody stems
rn = average annual harvest rate,
gm/m2/yr [0]
XH = fraction contaminant in harvested
biomass
F = average annual excess litter fall,
gm/m2/yr[1600]
a = average annual specific litter decay
rate, yf1 [0.15]
XL = fraction contaminant in remaining
litter. [0.2]
The word excess used above means
above background. System parameters
were estimated for operation of the Hough-
ton Lake treatment site. Utilizing the mass
balance equation, the predicted nitrogen
from progression was calculated. The
observed system behavior and the predic-
tion, based on the data given above, for the
nitrogen front movement are shown in
Figure 4. These data are from operational
specifications and prior field research.
The expansion of the "saturated" zones
about the discharge point have been found
200
1
•I
Q.
Q
5
I
;oo -
Figure 4. Movement of nitrogen (NHS-N) concentration fronts in surface waters, C= 1 mg/l.
Houghton Lake treatment site.
to be much as predicted by the material
balance, considering only the principal
mechanisms. The aging of the Houghton
Lake site can so far be described by this
model.
Wetland System Design:
Synthesis
The design process consists of two
distinct phases, synthesis and analysis.
Synthesis is the development of a plan for
a wastewater treatment facility. Analysis
is the evaluation of that plan and con-
cludes by acceptance of the proposed
design or rejection and another try at
synthesis There are no explicit equations
for synthesis. Design parameters are
chosen based upon past experience or
educated guesses.
If a wetland treatment system is to be
built in a natural wetland, the designer
may have little freedom in synthesis. This
phase may consist largely of site selection.
Since one of the principal costs in wetland
treatment is a wastewater delivery system
(piping, pumps, etc.), proximity of the site
is fundamental. Technical questions are
not the only ones which the designer must
address. Land ownership, political con-
siderations, and public attitudes must be
investigated. In the case of a natural
wetland site, environmental impacts will
be of particular concern. It is extremely
important to maintain open channels of
communication between the designers
and the community, regulatory agencies
and any other concerned parties.
With a natural wetland, the only con-
struction needed is often a wastewater
delivery line. Since wetlands tend to be at
low elevations, delivery can sometimes be
accomplished without a transfer pump, by
gravity flow. Wastewater can be effective-
ly applied to the wetland by a number of
schemes. If flows are small (less than
about 100,000 gallons per day) water can
be discharged from several nozzles or
even at a single point Larger flows can
be better accommodated by a linear dis-
charge. This can be conveniently obtained
by using gated irrigation pipe. The choice
of material for distribution lines is gen-
erally aluminum irrigation pipe or plastic
pipe. At northern sites, provision for
draining the lines in winter should be
included to prevent damage by ice. In
some cases, these lines can be run directly
on the surface of the wetland soi I • however,
provision should be made to prevent the
pipe from sinking into the peat under its
weight when filled. The distribution piping
has been successfully supported by logs
or an elevated platform, which also serve
as a convenient walkway.
Placement of pipe, platforms and other
material in the wetland can pose a prob-
lem. In northern climes, this is often best
accomplished when ice cover has formed.
Heavy equipment can be used with min-
imal residual damage to the vegetation.
The construction of artificial marshes
for wastewater treatment theoretically
provides a number of technical advan-
tages. Control can easily be maintained
over water levels and flow rates. The soil
plants and other component parts in-
cluded in the system can be selected for
their ability to treat wastewater. Treat-
-------
ment cells can be shaped like ditches or
large basins, which can be lined to assure a
bottom seal. The wetland can be built in a
configuration which permits easy harvest-
ing of biomass. Cells can be operated in
batch-mode, offering reliable control on
the quality of effluent. The constructed
wetland can be located conveniently.
The political advantages may be even
greater than these technical advantages.
While objections are sometimes raised to
wetland treatment sites utilizing natural
marshes, the constructed wetland con-
cept circumvents much of the controversy.
In many aspects, the constructed wetland
is akin to a piece of processing equipment
at the municipal treatment plant
Operation of a wetland treatment facility
generally involves establishment of a dis-
charge schedule and monitoring activities.
In certain cases, biomass harvesting may
also be considered. The discharge sched-
ule in northern climates is usually seasonal.
Wastewater is held in ponds during the
winter and discharged only during the
warm months, when plants, algae, and
microorganisms are most active.
Economics
The economics of wetland treatment are
attractive in those situations where a suit-
able land parcel exists adjacent to the
community. This appears to be true
whether or not an existing wetland elimi-
nates some construction costs.
The basis for an estimate must contain
the following key items:
1. Total acreage to be obtained, for
both irrigation and isolation.
2. Flows, both annual average and
irrigation season actual.
3. Distance to the wetland from the
treatment site.
4. Length of distribution pipe required
within the wetland.
5. Pumping requirements, if any, ex-
pressed in terms of static, friction
and site discharge heads.
6. Disinfection requirements.
7. Harvesting requirements.
8. Grading, ditching and diking re-
quirements.
9. Plant community establishment
10. Wetland discharge collection sys-
tem.
The first seven items are common to all
systems; the last three pertain only to
constructed wetlands.
This type of analysis shows the major
contributions to capital costs for an exist-
ing wetland to be pumps and piping, land
and land access.and disinfection. Site
alteration must be added for a constructed
wetland. The major contributions to oper-
ating and maintenance expense are man-
power, pumping energy, and monitoring
costs.
Capital costs, estimated and actual, are
shown in Figure 5. The estimates are
those of Sutherland (1978). The data are
lower than these estimates for four cases
and higher for two cases.
Operation and maintenance (0 & M)
costs are shown in Figure 6, with Suther-
land's (1978) estimates as a referent.
Data are sparse, and difficult to determine
accurately, but actual systems are cheap
to run by any standard. They require little
attention, essentially no chemicals, and
have simple equipment
Capital recovery costs and 0 & M costs
combine to yield a cost for advanced
secondary treatment for a gallon of waste-
water. Figure 7 gives Fritz and Helle's
(1978) estimates for cypress strands for
Legend
Estimates,
Sutherland (1978)
200,000 gpd facilities. Sutherland's esti-
mates for comparable size facilities are
included, using a capital recovery factor of
0.1. Data are in reasonable agreement
with their estimates. Thus, from a cost
viewpoint, wetland treatment looks attrac-
tive for small communities with appro-
priate land/wetland availability.
References
Fritz, W. R. and S. C. Helle. 1978. Cypress
Wetlands as a Natural Treatment Method
for Secondary Effluents. In: Environ-
mental Quality Through Wetlands Utili-
zation, MA Drew, ed. Coord. Council on
the Restoration of the Kissimmee River
Valley, pp. 69-81.
Sutherland, J. C. 1 978. Investigation of
the Feasibility of Tertiary Treatment of
Municipal Stabilization Pond Effluent
Using River Wetlands in Michigan.
Report to NSF, Grant # NV76-2081 2.
Data
Maple Rapids, Ml
7,000. — Deckerville, Ml
800
600
400
200
n
Edmore, Ml
Maple Rapids, Ml
Marcellus, Ml
Onekama, Ml
Rosebush, Ml
Scottville, Ml
St. Charles. Ml
Westphalia, Ml
~
HL 0
B
L MR^
_ B x-
QSC
Bw
(8 R B D
B S i
QAG
QD
Of
O/W?
QM
QO
QR
QS
QSC
QW
M
Q
x-
^
i
Houghton Lake, Ml B HL
Bellaire. Ml B B
Vermontville, Ml S V
Unnamed, Ml B SU
Drummond. Ml B D 0 ^
Listowell, ONT B Z. ./•''
Humboldt. SASK B J .,
Riverside, IA B fl ^
W ^ QD
Q ^
^
^
-X "
^ O
QAG
1 i i i i
Figure 5.
2.3 4 5
Pond-Wetland Distance (Miles), D
Wetland capital costs versus wetland distance from pond/adapted from Sutherland,
1978). (See Table 1 for site symbol identification.) Pipeline costs predominate.
-------
Legend
Estimates,
Sutherland (1978)
Data
«s
s.
2
<*
o
15
10
Maple Rapids, Ml
Deckerville, Ml
Edmore, Ml
Maple Rapids, Ml
Marcellus, Ml
Onekama, Ml
Rosebush, Ml
St. Charles, Ml
Westphalia. Ml
_SO s
8 HL
g V
B SU ,
QAG
OD
0£
QMR
QM
00
QR
OS
QSC
OW
Houghton Lake. Ml B HL
Bellaire. Ml B B
Vermontvil/e, Ml S V
Unnamed, Ml B SU
Drummond, Ml B D
Listowell, ONT B L
Humboldt, SASK B J
Riverside, IA g H
O
0
___ OD
Figure 6.
12345678
Pond- Wetland Distance (Miles)
Wetland 0 & M cqsts versus wetland distance (adapted from Sutherland, 1978)
(See Table 1 for symbol identification.) Line is for Sutherland estimates.
D. E. Hammer and R. H. Kadlec are with Department of Chemical Engineering,
University of Michigan, Ann Arbor, Ml 48109
William R. Duffer is the EPA Project Officer (see below).
The complete report, entitled "Design Principles for Wetland Treatment Systems,"
(Order No. PB 83-188 722; Cost: $22.00, subject to change) will be available
only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Robert S. Kerr Environmental Research Laboratory
U.S. Environmental Protection Agency
Ada, OK 74820
. S. GOVERNMENT PRINTING OFFICE: 1983/659-095/1948
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Legend
Estimates,
Sutherland ft978)
Maple Rapids. Ml Q AG
Houghton Lake, Ml
Bellaire, Ml
Vermontville, Ml
Unnamed. Ml
Drummond. Ml
Listowell. ONT
Humboldt. SASK
Riverside, IA
Deckerville, Ml QD
Edmore. Ml Of
Maple Rapids. Ml 0 MR
Marcellus, Ml
Onekama, Ml
Rosebush, Ml
Scottville, Ml
St. Charles, Ml
Westphalia. Ml
10.0
Length of Force Main (Miles)
Figure 7.
Incremental cost estimate lor advanced secondary wetland treatment (adapted from
Fritz & Helle. 1978). Curves based on 0.2 Mgd. No land cost for $1000/acre.
(See Table 1 for symbol identification.)
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Postage and
Fees Paid
Environmental
Protection
Agency
EPA 335
Official Business
Penalty for Private Use $300
PS 0000529
U S ENViH PROTtCTIOiM AGENCY
REGION 5 LI8RAHY
230 S DtARBORN STREET
CHICAGO IL 60604
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