EPA/600/A-94/228
WETLANDS TREATMENT DAiAUASfc,
Jerry D. Waterman
Donald S. Brown
U.S. Environmental Protection Agency
Office of Research & Development
Risk Reduction Engineering Laboratory
Cincinnati, Ohio
ABSTRACT: The U.S. EPA sponsored a project to collect and catalog information from
wastewater treatment wetlands into a computer database. EPA has also written a user friendly,
stand-alone, menu-driven computer program to allow anyone with DOS 3.3 or higher to access
the information in the database. The database and program were released to the general
public in the summer of 1994. This paper discusses the database and the accompanying
program.
The database contains information for 323 wetland cells at 178 locations in the U.S. and
Canada. The information provided includes general information (e.g. names of contacts,
dimensions, media and plants used, permit limits) as well as water quality data (BOD, TSS, N-
series, P, DO, and fecal coliforms). The database is a collection of existing information; no new
data were generated by this project.
KEYWORDS: Wetlands, Database, Water, Wastewater, Treatment of Wastewater
Introduction
Interest in the use of wetlands for the treatment of a variety of wastewaters is quickly
growing in the United States and worldwide. In 1990, the U.S. Environmental Protection
Agency (EPA), Office of Research and Development, began to collect information on existing
wetlands in the United States which treated wastewater. The collection effort evolved into the
Wetlands Treatment Database (North American Wetlands for Water Quality Treatment .
Database) described in this paper. Data collection ended in 1993. Papers discussing earlier
phases of the project have been presented (Brown and Reed, 1992; Knight, Kadlec, and Reed
1992; Knight, Ruble, Kadlec, and Reed, 1993; Knight, 1994; Reed, 1991; Reed and Brown,
1992).
Because treatment wetlands are an emerging technology, design and performance data
are limited and often difficult to obtain. Given the difficulty in locating and obtaining data, the
primary purpose of the database was to compile existing data and make it readily available to
the wastewater treatment community. During the compilation it became apparent that while
some wetlands had been monitored extensively, many wetlands had little or no available data.
In many cases data: 1) did not exist, 2) existed but were difficult to locate, 3) existed but had
not been released by the owners, or 4) existed but were not collected due to funding limitations.
Regardless of the lack of data for some systems, the database is thought to be the most
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complete collection of information on wetland treatment systems available. Although EPA does
not expect to update the database, the database will be useful as a framework for users to
continue to compile information. The database also makes apparent data gaps which will help
to focus new research and monitoring efforts.
Database Organization
Wetlands were entered into the database by geographic location or "site". Some sites
had multiple "systems" (wetland treatment trains that were in parallel and that had individual
outflows). Some systems had multiple "cells" (wetland areas that were clearly separated by
dikes or uplands and had identifiable inlets and outlets). Multiple cells in a system were in
series or in parallel. For example, the fictitious site shown in Figure 1 has two systems and
seven cells.
system 1
Effluent
Influent
Effluent
system 2
cell
cell
cell
cell
cell
cell
Figure 1. Relationship between "systems" and "cells"
The data were stored in nine files generated using dBASE IV\ Table I summarizes the
file structure and size. To make an analogy to a spreadsheet or table format, "fields" and
"records" can be thought of as columns and rows, respectively. More details about the data files
can be found in the database program itself and elsewhere (Knight, Ruble, Kadlec, and Reed,
1993).
Table I. Database File Structure
File Name
Description
No. of
Fields
Number of
Records
Total File
Size (Kb)
SITES.DBFa
General site (location)
information
56
178
37
SITES.DBTb
General notes about site
Data quality statements
1
173
143
SYSTEMS.DBF
System specific information
16
203
28
a) .DBF is a standard database file
b) .DBT is a database memo file
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Table I (continued). Database File Structure
pile Name
Description
No. of
Fields
Number of
Records
Total File
Size (Kb)
rF.LLS.DBF
Cell specific information
21
323
83
people.dbf
Contact people for the site
8
287
83
IJTERAT.DBF
References for the site
11
286
140
permits.dbf
Permit information for a
system/cell
10
475
60
OPERATE.DBF
Water quality data for a
system/cell
79
3229
2240
operate.dbt
Notes about water quality
data
1
123
70
Existing wetlands treating stormwater or municipal or industrial wastewater in North
America were included in the database. Both subsurface flow (SF) and free water surface
(FWS) wetlands, and both natural and constructed wetlands were included. (SF wetlands were
referred to as vegetated submerged beds (VSB) in some of the earlier references to the
database.) Agricultural and mining wastewater systems were specifically excluded. Figure 2
shows the location of the database systems in the U.S.; five locations in Canada were also
included. As shown in Figure 3, the majority of the systems treated municipal wastewater. The
"Other" category includes systems where the source of wastewater was unknown, and unique
systems such as the Des Plaines River experimental project which was used for improving river
water quality.
Municipal (154)
Industrial
^ /Stormwater
/ (6)
Other (8)
Figure 3. Type of Wastewater Treated
Figure 2. Location of treatment
wetlands in the U.S.
In general, only systems that treated greater than 38 m^/d (10,000 gpd) were included.
A few smaller pilot scale systems were included, but individual home systems were excluded.
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Figure 4 shows the range, mean, and median for actual flows (rather than design flows) for five
types of wetlands. These five types (CSM = constructed SF marsh, CFM = constructed FWS
marsh, NFM = natural FWS marsh, CHM = constructed hybrid (combination of SF and FWS)
marsh, and NFF = natural FWS forest) account for most of the systems in the database.
Figure 5 shows the distribution of wetlands by origin (natural or constructed), and within each
origin, distribution by hydrologic type (FWS, SF or hybrid). "Other" in Figure 5 includes
unknown and'hybrid (combination of natural and constructed) wetlands.
CSM
CFM
NFM
CHM
NFF
M A
1 101 102 1 03 1 04 1 05 1 06
Flow (m3/d)
Figure 4. Size (flow) by wetland type
I
Natural
| Constructed (151)
(«)
)ther(4)


i
i
FWS (89)
SF (48)
HI
B (14)
FWS (47)
SF(1)
Figure 5. Distribution by origin and
hydrologic types
As stated earlier, treatment wetlands are an emerging technology and data did not exist
for some systems. Table II summarizes the availability of data. The "Number of Sites" column
shows how many sites had information for each data file. For example, there were 286 records
for LITERAT.DBF, indicating that there were 286 literature citations. However, these citations
pertained to only 80 of the wetland sites. By comparing the number of sites (in this case, 80)
with the total number of 178 sites in the database, or with the number of data file records (in
this case, 286), the reader can get an indication of the availability of each type of data.
Table II. Availability of Data
File Name
Number of Records
Number of Sites
% Full
SITES.DBF
178
178
80
SYSTEMS.DBF
203
178
71
CELLS.DBF
323
128
67
PEOPLE.DBF
287
164
96
LITERAT.DBF
286
80
73
PERMITS.DBF
475
85
88
OPERATE.DBF
3229
94
50
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The "Percent Full" column of Table II also gives an indication of data availability by
wing the percentage of data fields that contain information. For example, 50% of the fields
QpERATE.DBF are empty. This does not mean that 50% of the sites did not have data. It
J^eans that for the 94 sites that did have data, 50% of the fields are empty. However, the
mbers in this column can be misleading. Some of the empty fields can explained by the
redundancy of some of the fields (i.e. mass loading and concentation), as discussed below.
Description of the Database and WTS Program
The database files include general site information, system specific information,
information for individual cells, names and addresses of people who are involved with or have
relevant knowledge about the wetland, literature references for wetland sites in the database,
permit information, and operational flow and water quality data for individual cells and/or
svstems. To make the database information more accessible to the user, the EPA created a
Jser friendly, stand-alone computer program ("Wetland Treatment Systems" or WTS) to allow
anyone with DOS 3.3 or higher to access the information in the database. A minimum of 640K
of memory and 4MB of free disk space is required to run the software.
The WTS program is an interface that allows the user to look at most of the information
in the wetlands treatment database without purchasing additional software. To access the
complete database, to sort or search the data files, or to do in-depth analyses of the data, the
user will have to use one of the several commercially available software packages that can
access files generated by dBASE IV™.
The WTS program begins with three opening screens, including a Disclaimer on Data
Quality (see discussion of Data Quality below). The Welcoming Menu screen comes next and
gives the user seven menu choices. The first five menu choices lead to important information
about the database background, data quality, acknowledgements, database description, and
summary information. This information is presented on the monitor rather than as a hardcopy
manual or a "READ.ME" file. The last two choices let the user begin the program or return to
DOS.
When the user chooses to begin the program, the program presents a list of the wetlands
in the database and lets the user scroll through the list to pick the wetland of interest. Sites are
listed in alphabetical order by state and then by site name within each state. The list also
includes the source of the wastewater. After a site has been chosen, the user can choose from a
list of menu items on the "Site Menu", which access the various database files: Site Description,
People & Literature, Permits Information, Choose Another Site, Print Option, or Return to
Main Menu.
Site Description. The user can choose Site Description to view general information
about the site, including geographic location, total number of systems and cells at the site, type
of pretreatment, and design flow. Also included in this section is a comment field that may
have comments about the site history, anecdotal information, or general observations relative to
the site. The comments range from one short sentence up to several paragraphs. Narrative
statements about data quality, if available, are presented here. For all sections of the program,
if a site has no information, then a window appears on the screen to indicate that "No Data was
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found for this site". Conversely, multiple screens are automatically displayed in sequence if they
are needed to present all of the information pertinent to a site.
Many of the sites had water quality data that can be accessed from the Site Description
section of the program. The water quality data were entered by system or cell and by time
period. The database contains fields for the water quality parameters listed in Table III. For
each parameter there were six available fields for entering data (see Table IV). Although it
resulted in redundancy for some wetlands, six fields were necessary because the database
compilation depended on existing data. For example, some wetlands reported data only in
terms of mass loading, but did not report enough additional information to allow computation
of concentrations. Therefore, restricting the database to concentration data only would have
left some information unavailable. The data for each parameter were entered into as many of
the six fields as possible. Some wetlands had data for all three fields for either mass loading or
concentration, but not enough information was available to report both. Therefore, these
wetlands had 50% of their data fields blank, and yet had data for influent, effluent, and percent
removal (see Table II). Other wetlands had data for only one field (e.g. concentration percent
removal).
Table III. Water Quality Parameters
Biochemical Oxygen Demand (BOD)
Total Suspended Solids (TSS)
Total Kjeldahl Nitrogen (TKN)
Ammonia Nitrogen(AMN)
	Nitrate Nitrogen (NQ3)	
	Total Nitrogen (TN)	
Organic Nitrogen (OGN)
Dissolved Phosphorus (DP)
	Total Phosphorus (TP)	
Fecal Conforms (FEC)
	Dissolved Oxygen (DO)	
Table IV. Water Quality Data Fields
mass loading
(kg/ha/d)
concentration
(mg/L)
Influent
Influent
Effluent
Effluent
Percent Removal
Percent Removal
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Figure 6 shows the number of sites for which water quality data were available for each
arameier. Figure 7 shows that the amount of water quality data available for a given site
varied considerably from no data to over 100 data records.
Figure 6, Extent of Water Quality Data	Number of Recads per Site
Figure 7. Distribution of water quality data
After viewing the water quality data screens, the user can see more specific information
about the systems and cells. Some of the sites have multiple screens to show the multiple
systems and/or cells at a site. The screen(s) with system data include origin type, hydrologic
type, vegetation type, area (ha), flow (m3/d), start date, down date, and cost information. The
screen(s) with cell data include vegetation species, length, width, depth, substrate, aspect, and
for subsurface flow wetlands, media, bottom slope and top slope.
People, Permits, Printing. After the user has reviewed the Site Description information
the "Site Menu" will reappear. The user can then view additional information about the current
site, select another site to view, or choose the print option. Additional information about the
current site includes either People & Literature or Permits Information. On the People &
Literature screen(s), information is shown about people familiar with the site including name,
address, and phone number. Next, literature information is shown with the author(s), title, year,
and the citation for the article. A comprehensive literature search was not done in the
compilation of the database. The reports included were often the type of gray literature (e.g.
student theises and reports to regulatory agencies) that are difficult to locate. These literature
citations can be consulted for more detailed information about systems in the database.
Using the Permits Information option the user can view the permit information for that
site. Information on the permit screen(s) includes design flow, limit, units, duration, parameter,
season, and comments for each permitted condition. Figure 8 shows the types of parameters
for which permit limits had been written for treatment wetlands. The N/P column includes all
types of nitrogen and phosphorus limits. The miscellaneous (MISC) column included a wide
range of site specific limits including metals, ultimate oxygen demand, and synthetic organics.
Because most permits had limits for several parameters, and often had different limits,
durations, or seasons that applied for a given parameter, a wetland system usually had more
than one record. Figure 9 shows that the types of permits written vary considerably from
permits with one record (i.e. limit) to permits with over 20 records.
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Figure 8. Types of permits written	Number of Records per Site
Figure 9. Distribution of permit records
Finally, using the Print option the user can print some or all of the information about the
selected site to a printer or to an ASCII text file. If the user sends the information to a text
file, the user can review the information later, incorporate it into a report, or import it into a
spreadsheet or other software application that will accept ASCII files.
Data Quality
Much of the information in the database had been collected over the past 15 years by
the principal database team members (see acknowledgements). Information was requested or
retrieved for all sites; however, most systems had only a limited amount of design or
operational data. As information was obtained it was converted, as necessary, to the units used
by the database. Data reduction and entry into the database was conducted by the principal
team members or under their direct supervision. All data were reviewed by the principal team
members for apparent aberrant values before entry into the database. Any values suspected of
being in error were confirmed with the original source of the information or were discarded.
The principal team members carefully reviewed the data for which they were responsible as
well as the data entered by the other team members. No other quality control checks were
conducted on the database.
The quality of the data in the OPERATE data file was not always known. For those
sites where it was known, the quality was sometimes difficult or impossible to verify. Data
quality depended on all of the people involved with the collection, transportation and analysis
of water samples. Procedures to document and control this process (quality assurance and
quality control, QA/QC) at wetland treatment systems were highly variable. Many systems,
especially at smaller facilities, had no written QA/QC procedures and used relatively simple
analytical methods. Although the people involved in the process may have been conscientious
and used great care, there was usually no documentation of data quality. Some systems,
however, were larger or better funded and had very credible QA/QC procedures and
documentation of data quality.
Due to the variable nature of data quality and data validation, users should exercise
caution when interpreting and applying these data. The original sources of the data should be
86

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acted for more information about the quality of the data. Conservatism must be included
design and operation of new systems when using these data, because data errors can be
difficult to detect. Also, it is important to note that: 1) actual operational parameters were not
fylly described in the database; and 2) start-up data may not be representative of long-term
operation.
0ata Analyses
Due to the large number of variables included in the database, analysis of data in the
database was beyond the scope of this paper. Wetlands varied by origin, hydrologic type, age,
climate (e.g. temperature, precipitation, and evaporation), design criteria (e.g. aspect, area, and
hydraulic detention time), vegetation, source and strength of influent wastewater, and treatment
objectives. The variablility of data quality also complicates data analysis. Preliminary analyses
of the database have been done by Knight, Ruble, Kadlec, and Reed (1992, 1993, 1994), and
additional analyses have been included in this paper for illustrative purposes. This type of
analysis, which points toward general data trends is too preliminary and too broad in scope to
be used to design or evaluate an individual treatment wetland, but it does add to the general
understanding of treatment wetlands. More detailed analyses of the data should be forthcoming
with the release of the database as more people have access to the data.
Figures 2 through 5, 10, and 11, update information provided by Knight, Ruble, Kadlec,
and Reed (1993). The size distribution based on area for the five major types of wetlands is
shown in Figure 10. SF wetlands, on the average, are one to two orders of magnitude smaller
than FWS wetlands. Figure 11 shows the primary types of vegetation used. As expected, the
most common vegetation species found in treatment wetlands were cattail (Typha spp.) and
bulrush (Scirpus spp.). In contrast to European systems, only a small percentage of wetlands
had Phragmites (common reed) as the primary species.
CSM
CFM
NFM
CHM
NFF
MA
A = Mean
M-Wodlsn

1 1
M A




{ M A
	t	-I-1 "1			
M A
I 1
M
10"® 10"2 10'1 1 101 102 to3 104
Area (ha)
Figure 10. Size (area) by wetland type
Cattai
Bulrush
Hyacinths &
Duckweed 2%
Phragmites 2%
Unknown
5%
Other
Other Grasses,
Sedges, Reeds
Figure 11. Primary types of vegetation
The low cost of construction and annual operation has been one of the major factors
behind the growth in interest in treatment wetlands. As shown in Figures 12 and 13, the
database provides construction cost information for 67 wetlands, and annual operating cost
information for 15 wetlands. The categories of wetlands shown in these figures are;
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NSF
Small
Conv.
0.01

t
A = Mean
M = Median
O = OuUier
X = Single
Value
0.1 1 10 100 1,000
Unit Cost ($/GPD)
Figure 12. Construction Costs
NFWS
CFWS
CHYH(
A ¦ Mean
M ¦= Median
O <= OutJier
X = Single
Value
Small
Conv.
0.01 0.1	1	10
Annual Cost (S/1000 GAL)
Figure 13. Annual Operating Costs
100
NFWS = natural FWS; CFWS = constructed FWS; CSF = constructed SF; CHYB =
constructed hybrid; and NSF = natural SF. The year of the cost data was reported in the
database to allow users to update the costs to the present. Because of the wide range in costs,
and because the year of the cost data was not always known, the costs shown in Figures 12 and
13 were not updated. For Figure 12, the year of the cost data was reported for 36 of the 67
wetlands, and the year ranged from 1972 to 1993. For Figure 13, the year of the cost data was
reported for 11 of the 15 wetlands, and the year ranged from 1978 to 1993. For comparison,
the category "Small Conv." refers to a variety of conventional, natural and mechanical, small
community wastewater treatment technologies (package plants, trickling filters, oxidation
ditches, sequencing batch reactors, aerated lagoons, sand filters, and land application)(SAIC,
1992). As expected, costs for treatment wetlands of all types are equivalent or less than
conventional treatment methods.
Conclusion
The Wetlands Treatment Database was released in the summer of 1994 to the general
public. To request a copy or for questions about the database contents, contact Donald Brown,
Project Officer, (513) 569-7630. For questions about the software program, contact Jerry D.
Waterman, Software Developer, (513) 569-7834. Both can be reached at the Risk Reduction
Engineering Laboratory (RREL), U.S. EPA, 26 W. Martin L. King Dr., Cincinnati, OH 45268;
FAX: (513) 569-7787.
Acknowledgements
The data collection and database creation was done under contract by: Robert L
Knight, Ph.D. and Richard W. Ruble of CH2M HILL, Gainesville, Florida; Robert H. Kadlec,
Ph.D. of Wetland Management Services, Chelsea, Michigan; and Sherwood C. Reed, P.E.,
Environmental Engineering Consultants, Norwich, Vermont. The WTS program was developed
by Jeny Waterman, U.S.EPA, RREL. Technical support was provided by Richard Olson,
ManTech Environmental Technology, Corvallis, Oregon. Project oversight was provided by
88

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Id Brown, U.S.EPA, RREL, and William Sanville, U.S. EPA, Environmental Research
laboratory, Duiuth, Minnesota.
ptjclaimer
The database has been funded wholly or in part by the United States Environmental
Protection Agency under contracts 68-C0-0021 with Technical Resources, Inc., 68-C0-0027 with
Montgomery Watson Americas, Inc., and 68-C8-0006 with ManTech Environmental Technology,
Inc The database and this paper have been subjected to the Agency's peer and administrative
review, and have been approved for release as EPA documents. The data are presented for
rcview by the user. Therefore, the conclusions and opinions drawn from the data are solely
of the user and are not necessarily the views of the EPA. Mention of trade names or
commercial products does not constitute endorsement or recommendation for use.
References
grown, D.S. and Reed, S.C. (1992) Inventory of Constructed Wetlands in the United States.
Presented at the 1AWQ Specialist Conference "Wetland Systems in Water Pollution Control",
Sydney, Australia, Nov. 1992. To be published in Water Sci. & Technol. (in press).
Knight, R.L., Kadlec, R.H., Reed, S.C. (1992) Wetlands Treatment Data Base. In Proceedings
flf fhg 65th Annual Water Environ. Fed. Conf.. Volume IX. "General Topics". 25-35.
Knight, R.L, Ruble, R.W., Kadlec, R.H., and Reed, S.C. (1993) Wetlands for Wastewater
Treatment; Performance Database. In Constructed Wetlands for Water Quality Improvement.
Gerald A. Moshiri, ed., Lewis Publishers, Boca Raton, 35-58.
Knight, R.L. (1994) Treatment Wetlands Database Now Available. Water Environ. & Technol.
Feb. 1994, 31-33.
Reed, S.C. (1991) Constructed Wetlands for Wastewater Treatment. Biocvcle Jan 1991, 44-49.
Reed, S.C. and Brown, D.S. (1992) Constructed Wetland Design - The First Generation. Water
Environ. Res.. 64, 776-781.
Science Applications International Corporation (1992) Summary Report: Small Community
Water and Wastewater Treatment. U.S.EPA Office of Research and Development,
Washington, DC, EPA/625/R-92/010, Sep. 1992.
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TECHNICAL REPORT DATA
{Pleat*readInstructions an.tht.rrvmr.hr fnre completingf
1. REPORT NO. 2
EPA/600/A-94/228
3 RECIPIENT S ACCESSION NO.
4. TITLE and subtitle
Wetlands Treatment Database
S. REPORT DATE
6. PERFORMING ORGANIZATION COOE
7, AUTHQR(S)
Jerry D. Waterman and Donald S. Brown
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADORESS
U.S. Environmental Protection Agency
Risk Reduction Engineering Laboratory — Cincinnati, OH
Office of Research and Development
Cincinnati» OH 45268
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
68-C0-0021,68-CO-0029, 68-C8-
12. SPONSORING AGENCY NAME AND ADDRESS
Risk Reduction Engineering laboratory — Cincinnati, OH
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH 45268
13. TYPE OF REPORT AND PERIOD COVERED
Abstract & Proceedings
14. SPONSORING AGENCY CODE
EPA/600/14
is supplementary notes jgrry D. Waterman, (513) 569-7834 ,• Proceedings of the Water
Environment Federation, 67th Annual Conference S. Exposition , VIII, Chicago, IL,
in/lS-iq/Q4. p• 1Q_RQ
is. Abstract
The U.S. EPA sponsored a project to collect and catalog information from wastewater
'treatment wetlands into a computer database. EPA has also written a user friendly,
stand-alone, menu-driven computer program to allow anyone with DOS 3.3 or higher
to access the information in the database ." The database and program were released
to the general public in the summer of 1994.-—This paper discusses the database
and the accompanying program.
The database contains information for 323 wetland cells at 178 locations in the U.S.
and Canada. The information provided includes general information (e.g. names of
contacts, dimensions, media and plants used, permit limits) as well as water quality
data (BOD, TSS, N-series, P, DO, and fecal coliforms). The database is a collection
of existing information; no new data were generated by this project.^L=-=£'"
17. KEY WORDS AND DOCUMENT ANALYSIS
a. DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
WATER
WASTE WATER
WETLANDS
DATABASE
WASTEWATER TREATMENT

18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19, SECURITY CLASS /This Report)
UNCLASSIFIED
21. NO. OF PAGES
13
20 SECURITY CLASS (Thit page)
UNCLASSIFIED
22. PRICE
EP* F«r*v-7330-l (Ra«. 4-77) pkcvious ioition i j obsolete

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