United States

Environmental Protection

Agency

Office of Water

Washington, D.C.

EPA 832-F-00-023

September 2000

Wastewater

Technology Fact Sheet

Wetlands: Subsurface Flow

DESCRIPTION

Wetland systems are typically described in terms of

the position of the water surface and/or the type of

vegetation grown. Most natural wetlands are free

water surface systems where the water surface is

exposed to the atmosphere; these include bogs

(primary vegetation mosses), swamps (primary

vegetation trees), and marshes (primary vegetation

grasses and emergent macrophytes). A subsurface

flow (SF) wetland is specifically designed for the

treatment or polishing of some type of wastewater

and are typically constructed as a bed or channel

containing appropriate media. An example of a SF

wetland is shown in Figure 1. Coarse rock, gravel,

sand and other soils have all been used, but a gravel

medium is most common in the U.S. and Europe.

The medium is typically planted with the same types

of emergent vegetation present in marshes, and the

water surface is designed to remain below the top

surface of the medium. The main advantages of this

subsurface water level are prevention of mosquitoes

and odors, and elimination of the risk of public

contact with the partially treated wastewater. In

contrast, the water surface in natural marshes and

free water surface (FWS) constructed wetlands is

exposed to the atmosphere with the attendant risk of

mosquitoes and public access. 

The water quality improvements in natural wetlands

had been observed by scientists and engineers for

many years and this led to the development of

constructed wetlands as an attempt to replicate the

water quality and the habitat benefits of the natural

wetland in a constructed ecosystem. Physical,

chemical, and biochemical reactions all contribute to

water quality improvement in these wetland

systems. The biological reactions are believed due

to the activity of microorganisms attached to the

available submerged substrate surfaces. In the case

of FWS wetlands these substrates are the

submerged portion of the living plants, the plant

litter, and the benthic soil layer. In SF wetlands the

available submerged substrate includes the plant

roots growing in the media, and the surfaces of the

media themselves. Since the media surface area in

a SF wetland can far exceed the available substrate

in a FWS wetland, the microbial reaction rates in a

SF wetland can be higher than a FWS wetland for

most contaminants. As a result, a SF wetland can

be smaller than the FWS type for the same flow rate

and most effluent water quality goals.

The design goals for SF constructed wetlands are

typically an exclusive commitment to treatment

functions because wildlife habitat and public

recreational opportunities are more limited than

FWS wetlands. The size of these systems ranges

Vegetation

Inlet Manifold

Cold Climates

Outlet

Manifold

Water

Surface

Membrane Line or

Impermeable Soils

Treatment Zone

1/

2

” to 11/

2

” Gravel

Outlet Zone

2” to 3”

Gravel

Inlet Zone

2” to 3”

Gravel

Optional Inlet

Manifold Warm

Climates

Source: Adapted from drawing by S.C. Reed, 2000.

FIGURE 1 SUBSURFACE FLOW

WETLAND
from small on-site units designed to treat septic tank

effluents to a 1.5x107 liters per day (4 MGD) system

in Louisiana treating municipal wastewater. There

are approximately 100 systems in the U.S. treating

municipal wastewater, with the majority of these

treating less than 3.8x103 m3/day (1 MGD). Most of

the municipal systems are preceded by facultative or

aerated treatment ponds. There are approximately

1,000 small scale on-site type systems in the U.S.

treating waste waters from individual homes,

schools, apartment complexes, commercial

establishments, parks, and other recreational

facilities. The flow from these smaller systems

ranges from a few hundred gallons per day to

151,400 liters per day (40,000 gallons per day),

with septic tanks being the dominant preliminary

treatment provided. SF wetlands are not now

typically selected for larger flow municipal systems.

The higher cost of the rock or gravel media makes

a large SF wetland uneconomical compared to a

FWS wetland in spite of the smaller SF wetland area

required. Cost comparisons have shown that at flow

rates above 227,100 liters per day (60,000 gallons

per day) it will usually be cheaper to construct a

FWS wetland system. However, there are

exceptions where public access, mosquito, or

wildlife issues justify selection of a SF wetland. One

recent example is a SF wetland designed to treat the

runoff from the Edmonton Airport in Alberta,

Canada. The snow melt runoff is contaminated with

glycol de-icing fluid and a SF wetland treating

1,264,190 liters per day (334,000 gallons per day)

was selected to minimize habitat values and bird

problems adjacent to the airport runways. 

SF wetlands typically include one or more shallow

basins or channels with a barrier to prevent seepage

to sensitive groundwaters. The type of barrier will

depend on local conditions. In some cases

compaction of the local soils will serve adequately,

in other cases clay has been imported or plastic

membrane (PVC or HDPE) liners used.

Appropriate inlet and outlet structures are employed

to insure uniform distribution and collection of the

applied wastewater. A perforated manifold pipe is

most commonly used in the smaller systems. The

depth of the media in these SF wetlands has ranged

from 0.3 to 0.9 meters (1 to 3 feet) with 0.6 meters

(2 feet) being most common. The size of the media

in use in the U.S. ranges from fine gravel (≥0.6

centimeters or ≥ 0.25 in.) to large crushed rock

(≥15.2 centimeters or ≥6 in.); A combination of

sizes from 1.3 centimeters to 3.8 centimeters (0.5 to

1.5 inches) are most typically used. This gravel

medium should be clean, hard, durable stone capable

of retaining it’s shape and the permeability of the

wetland bed over the long term. 

The most commonly used emergent vegetation in

SF wetlands include cattail (Typha spp.), bulrush

(Scirpus spp.), and reeds (Phragmites spp.). In

Europe, Phragmites are the preferred plants for

these systems. Phragmites have several advantages

since it is a fast growing hardy plant and is not a

food source for animals or birds. However, in some

parts of the U.S. the use of Phragmites is not

permitted because it is an aggressive plant and there

are concerns that it might infest natural wetlands. In

these cases cattails or bulrush can be used. In areas

where muskrat or nutria are found, experience has

shown that these animals, using the plants for food

and nesting material, can completely destroy a stand

of cattails or bulrush planted in a constructed

wetland. Many of the smaller on-site systems

serving individual homes use water tolerant

decorative plants. The vegetation on a SF wetland

bed is not a major factor in nutrient removal by the

system and does not require harvesting. In cold

climates, the accumulating plant litter on top of the

gravel bed provides useful thermal insulation during

the winter months. The submerged plant roots do

provide substrate for microbial processes and since

most emergent macrophytes can transmit oxygen

from the leaves to their roots there are aerobic

microsites on the rhizome and root surfaces. The

remainder of the submerged environment in the SF

wetland tends to be devoid of oxygen. This general

lack of available oxygen limits the biological

removal of ammonia nitrogen (NH3/NH4 - N) via

nitrification in these SF wetlands, but the system is

still very effective for removal of BOD, TSS,

metals, and some priority pollutant organics since

their treatment can occur under either aerobic or

anoxic conditions. Nitrate removal via biological

denitrification can also be very effective since the

necessary anoxic conditions are always present and

sufficient carbon sources are usually available.

The limited availability of oxygen in these SF

systems reduces the capability for ammonia removal
via biological nitrification. As a result, a long

detention time in a very large wetland area is

required to produce low levels of effluent nitrogen

with typical municipal wastewater influents unless

some system modification is adopted. These

modifications have included installation of aeration

tubing at the bottom of the bed for mechanical

aeration, the use of an integrated gravel trickling

filter for nitrification of the wastewater ammonia,

and vertical flow wetland beds. These vertical flow

beds usually contain gravel or coarse sand and are

loaded intermittently at the top surface. The

intermittent application and vertical drainage

restores aerobic conditions in the bed permitting

aerobic reactions to proceed rapidly. Cyclic filling

and draining of a horizontal flow system has been

successfully demonstrated at the 130,000 gallons

per day SF wetland system in Minoa, NY. The

reaction rates for BOD5 and ammonia removal

during these cyclic operations were double the rates

observed during normal continuously saturated

flow.

The phosphorus removal mechanisms available in all

types of constructed wetlands also require long

detention times to produce low effluent levels of

phosphorus with typical municipal wastewater. If

significant phosphorus removal is a project

requirement then a FWS wetland will probably be

the most cost effective type of constructed wetland.

Phosphorus removal is also possible with final

chemical addition and mixing prior to a final deep

settling pond.

The minimal acceptable level of preliminary

treatment prior to a SF wetland system is the

equivalent of primary treatment. This can be

accomplished with septic tanks or Imhoff tanks for

smaller systems or deep ponds with a short

detention time for larger systems. The majority of

existing SF wetland systems treating municipal

waste waters are preceded by either facultative or

aerated ponds. Such ponds are not necessarily the

preferred type of preliminary treatment. At most of

these existing systems the SF wetland was selected

to improve the water quality of the pond effluent.

Since the SF wetland can provide very effective

removal for both BOD5 and TSS, there is no need to

provide for high levels of removal of these

constituents in preliminary treatments.

The SF wetland does not provide the same level of

habitat value as the FWS wetland because the water

in the system is not exposed and accessible to birds

and animals. However, wildlife will still be present,

primarily in the form of nesting animals, birds, and

reptiles. If provision of more significant habitat

values is a project goal it can be accomplished with

deep ponds interspersed between the SF wetland

cells. The first pond in such a system would be

located after the point where water quality is

approaching at least the secondary level

APPLICABILITY

SF wetland systems are best suited for small to

moderate sized applications (≤ 227,100 liters/day or

≤60,000 gallons per day) and at larger systems

where the risk of public contact, mosquitoes, or

potential odors are major concerns. Their use for

on-site systems provides a high quality effluent for

in-ground disposal, and in some States a significant

reduction in the final disposal field area is allowed.

SF wetlands will reliably remove BOD, COD, and

TSS, and with sufficiently long detention times can

also produce low levels of nitrogen and phosphorus.

Metals are removed effectively and about a one log

reduction in fecal coliforms can be expected in

systems designed to produce secondary or advanced

secondary effluents.

ADVANTAGES AND DISADVANTAGES

Some advantages and disadvantages of subsurface

flow wetlands are listed below.

Advantages

• SF wetlands provide effective treatment in a

passive manner and minimize mechanical

equipment, energy, and skilled operator

attention.

• SF wetlands can be less expensive to

construct and are usually less expensive to

operate and maintain as compared to

mechanical treatment processes designed to

produce the same effluent quality.
• Year-round operation for secondary

treatment is possible in all but the coldest

climates.

• Year-round operation for advanced or

tertiary treatment is possible in warm to

moderately temperate climates. The SF

wetland configuration provides more

thermal protection than the FWS wetland

type.

• SF wetland systems produce no residual

biosolids or sludges requiring subsequent

treatment and disposal.

• The SF wetland is very effective and reliable

for removal of BOD, COD, TSS, metals,

and some persistant organics in municipal

wastewaters. The removal of nitrogen and

phosphorus to low levels is also possible but

requires a much longer detention time.

• Mosquitoes and similar insect vectors are

not a problem with SF wetlands as long as

the system is properly operated and a

subsurface water level maintained. The risk

of contact by children and pets with

partially treated wastewater is also

eliminated. 

Disadvantages

• A SF wetland will require a large land area

compared to conventional mechanical

treatment processes.

• The removal of BOD, COD, and nitrogen in

SF wetlands are continuously renewable

processes. The phosphorus, metals, and

some persistent organics removed in the

system are bound in the wetland sediments

and accumulate over time.

• In cold climates the low winter water

temperatures reduce the rate of removal for

BOD, NH3, and NO3. An increased

detention time can compensate for these

reduced rates but the increased wetland size

in extremely cold climates may not be cost

effective or technically possible.

• Most of the water contained in the SF

wetland is anoxic and this limits the

potential for nitrification of wastewater

ammonia. Increasing the wetland size and

detention time will compensate, but this may

not be cost effective. Alternative methods

for nitrification in combination with a SF

wetland have been successful. SF wetlands

cannot be designed for complete removal of

organic compounds, TSS, nitrogen, and

coliforms. The natural ecological cycles in

these wetlands produce “background”

concentrations of these substances in the

system effluent.

• SF wetland systems can typically remove

fecal coliforms by at least one log. This is

not always sufficient to meet discharge

limits in all locations and post disinfection

may be required. UV disinfection has been

successfully used in a number of

applications.

• Although SF wetlands can be smaller than

FWS wetlands for the removal of most

constituents, the high cost of the gravel

media in the SF wetland can result in higher

construction costs for SF systems larger

than about 227,100 liters per day (60,000

gallons per day).

DESIGN CRITERIA

Published models for the design of SF wetland

systems have been available since the late 1980’s.

More recent efforts in the mid to late 1990’s have

produced three text books containing design models

for SF wetlands (Reed, et al 1995, Kadlec & Knight

1996, Crites & Tchobanoglous, 1998). In all three

cases, the models are based on first order plug flow

kinetics, but results do not always agree due to the

author’s developmental choices and because the

same databases were not used for derivation of the

models. The Water Environment Federation (WEF)

presents a comparison of the three approaches in

their Manual of Practice on Natural Systems (WEF,

2000) as does the US EPA design manual on

wetland systems (EPA, 2000). The designer of a SF

wetland system should consult these references and

select the method best suited for the project under
consideration. A preliminary estimate of the land

area required for a SF wetland can be obtained from

Table 1 of typical areal loading rates. These values

can also be used to check the results from the

previously cited references.

The SF wetland size is determined by the pollutant

which requires the largest land area for it’s removal.

This is the bottom surface area of the wetland cells

and, for that area to be 100 percent effective, the

wastewater flow must be uniformly distributed over

the entire surface. This is possible with constructed

wetlands by careful grading of the bottom surface

and use of appropriate inlet and outlet structures.

The total treatment area should be divided into at

least two cells for all but the smallest systems.

Larger systems should have at least two parallel

trains of cells to provide flexibility for management

and maintenance.

These wetland systems are living ecosystems and

the life and death cycles of the biota produce

residuals which can be measured as BOD, TSS,

nitrogen, phosphorus and fecal coliforms. As a

result, regardless of the size of the wetland or the

characteristics of the influent, in these systems there

will always be a residual background concentration

of these materials. Table 2 summarizes these

background concentrations. 

It is necessary for the designer to determine the

water temperature in the wetland because the

removal of BOD, and the various nitrogen forms are

temperature dependent. The water temperature in

large systems with a long HRT (>10 days) will

approach the average air temperature except during

subfreezing weather in the winter. Methods for

estimating the water temperature for wetlands with

a shorter HRT (<10 days) can be found in the

published references mentioned previously.

It is also necessary to consider the hydraulic aspects

of system design because there is significant

frictional resistance to flow through the wetland

caused by the presence of the gravel media and the

plant roots and other detritus. The major impact of

this flow resistance is on the configuration selected

for the wetland cell. The longer the flow path the

higher the resistance will be. To avoid these

hydraulic problems an aspect ratio (L:W) of 4:1 or

less is recommended. Darcy’s law is generally

accepted as the model for the flow of water through

SF wetlands and descriptive information can again

be found in the published references mentioned

previously. The flow of water through the wetland

cell depends on the hydraulic gradient in the cell and

on the hydraulic conductivity (ks), size, and porosity

(n) of the media used. Table 3 presents typical

characteristics for potential SF wetland media.

These values can be used for a preliminary estimate

and for design of very small systems. For large

scale systems the proposed media should be tested

to determine these values.

TABLE 1 TYPICAL AREAL LOADING RATES FOR SF CONSTRUCTED WETLANDS

Constituent Typical Influent

Concentration mg/L

Target Effluent

Concentration mg/L

Mass Loading Rate

lb/ac/d*

Hydraulic Load (in./d) 3 to 12**

BOD 30 to175 10 to 30 60 to 140

TSS 30 to150 10 to 30 40 to 150

NH3/NH4 as N 2 to 35 1 to 10 1 to 10

NO3 as N 2 to 10 1 to 10 3 to 12

TN 2 to 40 1 to 10 3 to 11

TP 1 to 10 0.5 to 3 1 to 4

Note: Wetland water temperature » 20°C.
PERFORMANCE 

A lightly loaded SF wetland can achieve the

“background” effluent levels given in Table 2. In

the general case, the SF constructed wetland is

typically designed to produce a specified effluent

quality and Table 1 can be used for a preliminary

estimate of the size of the wetland necessary to

produce the desired effluent quality. The design

models in the referenced publications will provide a

more precise estimate of treatment area required.

Table 4 summarizes actual performance data for 14

SF wetland systems included in a US EPA

Technology Assessment (EPA, 1993).

In theory, the performance of a SF wetland system

can be influenced by hydrological factors. High

evapotranspiration (ET) rates may increase effluent

concentrations, but this also increases the HRT in

the wetland. High precipitation rates dilute the

pollutant concentrations but also shorten the HRT

in the wetland. In most temperate areas with a

moderate climate these influences are not critical for

performance. These hydrological aspects need only

be considered for extreme values of ET and

precipitation.

OPERATION AND MAINTENANCE

The routine operation and maintenance (O&M)

requirements for SF wetlands are similar to those

for facultative lagoons, and include hydraulic and

water depth control, inlet/outlet structure cleaning,

grass mowing on berms, inspection of berm

integrity, wetland vegetation management, and

routine monitoring.

The water depth in the wetland may need periodic

adjustment on a seasonal basis or in response to

increased resistance over a very long term from the

accumulating detritus in the media pore spaces.

Mosquito control should not be required for a SF

wetland system as long as the water level is

maintained below the top of the media surface.

Vegetation management in these SF wetlands does

not include a routine harvest and removal of the

TABLE 2 “BACKGROUND” SF

WETLAND CONCENTRATIONS

Constituent Units Concentration

Range

BOD5 mg/L 1 to 10

TSS mg/L 1 to 6

TN mg/L 1 to 3

NH3/NH4 as N mg/L less than 0.1

NO3 as N mg/L less than 0.1

TP mg/L less than 0.2

Fecal Coliforms MPN/100ml 50 to 500

Source: Reed et al., 1995 and U.S. EPA, 1993.

TABLE 3 TYPICAL MEDIA CHARACTERISTICS FOR SF WETLANDS

Media Type Effective Size D10

(mm)*

Porosity, n (%) Hydraulic Conductivity ks

(ft3/ft2/d)*

Coarse Sand 2 28 to 32 300 to 3,000

Gravelly Sand 8 30 to 35 1,600 to 16,000

Fine Gravel 16 35 to 38 3,000 to 32,000

Medium Gravel 32 36 to 40 32,000 to 160,000

Coarse Rock 128 38 to 45 16 x 104 to 82 x 104

* mm x 0.03937 = inches

** ft3/ft2/d x 0.3047 = m3/m2/d, or x 7.48 = gal/ft2/d

Source: Reed et al., 1995.
harvested material. Plant uptake of pollutants

represents a relatively minor pathway so harvest and

removal on a routine basis does not provide a

significant treatment benefit. Removal of

accumulated litter is unnecessary, and in cold

climates it serves as thermal insulation to prevent

freezing in the wetland bed. Vegetation

management may also require wildlife management,

depending on the type of vegetation selected for the

system, and the position of the water. Animals such

as nutria and muskrats have been known to

consume all of the emergent vegetation in

constructed wetlands. These animals should not be

attracted to a SF wetland as long as the water level

is properly maintained. Routine water quality

monitoring will be required for all SF systems with

an NPDES permit, and the permit will specify the

pollutants and frequency. Sampling for NPDES

monitoring is usually limited to the untreated

wastewater and the final system effluent. Since the

wetland component is usually preceded by some

form of preliminary treatment, the NPDES

monitoring program does not document wetland

influent characteristics. It is recommended, in all

but the smallest systems that periodic samples of the

wetland influent be obtained and tested for

operational purposes in addition to the NPDES

requirements. This will allow the operator a better

understanding of wetland performance and provide

a basis for adjustments if necessary.

COSTS

The major items included in the capital costs for SF

wetlands are similar to many of those required for

lagoon systems. These include land costs, site

investigation, site clearing, earthwork, liner, gravel

media, plants, inlet and outlet structures, fencing,

miscellaneous piping, etc., engineering, legal,

contingencies , and contractor’s overhead and

profit. The gravel media and the liner can be the

most expensive items from this list. In the Gulf

States where clay soils often eliminate the need for

a liner the cost of imported gravel can often

represent 50 percent of the construction costs. In

other locations where local gravel is available but a

membrane liner is required the liner costs can

approach 40 percent of the construction costs. In

many cases compaction of the in-situ native soils

provides a sufficient barrier for groundwater

contamination. Table 5 provides a summary of

capital and O & M costs for a hypothetical 378,500

liters/day (100,000 gallons per day) SF constructed

wetland, required to achieve a 2 mg/L ammonia

concentration in the effluent. Other calculation

assumptions are as follows: influent NH3= 25 mg/L,

water temperature 20°C (68°F), media depth = 0.6

meters (2 ft), porosity = 0.4, treatment area = 1.3

hectares (3.2 ac), land cost =$12,355/hectare ($5,000/ac).

TABLE 4 SUMMARY OF PERFORMANCE FOR 14 SF WETLAND SYSTEMS*

Constituent Mean Influent mg/L Mean Effluent mg/L

BOD5 28** (5-51)*** 8** (1-15)***

TSS 60 (23-118) 10 (3-23)

TKN as N 15 (5-22) 9 (2-18)

NH3/NH4 as N 5 (1-10) 5 (2-10)

NO3 as N 9 (1-18) 3 (0.1-13)

TN 20 (9-48) 9 (7-12)

TP 4 (2-6) 2 (0.2-3)

Fecal Coliforms (#/100ml) 270,000 (1,200-1,380,000) 57,000 (10-330,000)

* Mean detention time 3 d (range 1 to 5 d).

** Mean value.

*** Range of values.

Source: U.S. EPA, 1993.
Table 6 compares the life cycle costs for this

wetland to the cost for a conventional treatment

system designed for the same flow and effluent

water quality. The conventional process is a

sequencing batch reactor (SBR).

REFERENCES

Other Related Fact Sheets

Free Water Surface Wetlands

EPA 832-F-00-024

September, 2000

Other EPA Fact Sheets can be found at the

following web address:

http://www.epa.gov/owmitnet/mtbfact.htm

TABLE 5 CAPITAL AND O&M COSTS FOR 100,000 GALLONS PER DAY SF WETLAND

Item Cost $*

Native Soil Liner Plastic Membrane Liner

Land Cost $16,000 16,000

Site Investigation 3,600 3,600

Site Clearing 6,600 6,600

Earthwork 33,000 33,000

Liner 0 66,000

Gravel Media** 142,100 142,100

Plants 5,000 5,000

Planting 6,600 6,600

Inlets/Outlets 16,600 16,600

Subtotal $229,500 $295,500

Engineering, legal, etc. $133,000 $171,200

Total Capital Cost $362,500 $466,700

O & M Costs, $/yr $6,000/yr $6,000/yr

* June 1999 costs, ENR CCI = 6039

**12,000 cy of 0.75 in. gravel

TABLE 6 COST COMPARISON SF WETLAND AND CONVENTIONAL WASTEWATER

TREATMENT

Cost Item

Process

Wetland SBR

Capital Cost $466,700 $1,104,500

O &M Cost $6,000/yr $106,600/yr

Total Present Worth Costs* $530,300 $2,233,400

Cost per 1000 gallons treated** $0.73 $3.06

*Present worth factor 10.594 based on 20 years at 7 percent interest (June 1999 costs, ENR CCI = 6039).

**Daily flow rate for 365 d/yr, for 20 yr, divided by 1000 gallons

Source: WEF, 2000.
For more information contact:

Municipal Technology Branch

U.S. EPA

Mail Code 4204

1200 Pennsylvania Avenue, NW

Washington, D.C., 20460

1. Crites, R.W., G. Tchobanoglous (1998)

Small and Decentralized Wastewater

Management Systems, McGraw Hill Co.,

New York, New York.

2. Kadlec, R.H., R. Knight (1996)Treatment

Wetlands, Lewis Publishers, Boca Raton,

Florida.

3. Reed, S.C., R.W. Crites, E.J. Middlebrooks

(1995) Natural Systems for Waste

Management and Treatment - Second

Edition, McGraw Hill Co, New York, New

York.

4. U.S. EPA (1999) Free Water Surface

Wetlands for Wastewater Treatment: A

Technology Assessment, US EPA, OWM,

Washington, DC. (in press.)

5. U.S. EPA (2000) Design Manual

Constructed Wetlands for Municipal

Wastewater Treatment, US EPA CERI,

Cincinnati, Ohio (in press.)

6. US. EPA (1993) Subsurface Flow

Constructed Wetlands for Wastewater

Treatment A Technology Assessment, EPA

832-R-93-008, US EPA OWM,

Washington, DC.

7. Water Environment Federation (2000)

Natural Systems for Wastewater Treatment,

MOP FD-16, WEF, Alexandria, Virginia (in

press.)

ADDITIONAL INFORMATION

Southwest Wetlands Group

Mr Michael Ogden

901 W. San Mateo, Suite M, 

Santa Fe, NM 87505

City of Mandeville

Mr Joe Mistich, Public Works Director

3101 E. Causway Approach

Mandeville, LA 70448-3592

TVA

Mr James Watson

311 Broad Street, HB 25 27OC - C

Chattanooga, TN 37402-2801

EMC Group, Inc.

Mr Charles King

PO Box 22503

Jackson, MS 39205

Village of Minoa WWTP

Mr Steve Giarrusso

213 Osborne Street

Minoa, NY 13116

The mention of trade names or commercial products

does not constitute endorsement or recommendation

for use by the U.S. Environmental Protection

Agency.