United States
Environmental Protection
Agency
Municipal Environmental Research EPA-600/2-80-094
Laboratory August 1980
Cincinnati OH 45268 •
Research and Development
&EPA
Impact of Urban
Storm Runoff on
Stream Quality Near
Atlanta, Georgia
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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 ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa- •
tion Service, Springfield, Virginia 22161.
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EPA-600/2-80-094
August 1980
IMPACT OF URBAN STORM RUNOFF ON STREAM
QUALITY NEAR ATLANTA, GEORGIA
by
James B. McConnell
U.S. Geological Survey
Water Resources Division
Doraville, Georgia 30360
Interagency- Agreement No. EPA-IAG-D6-0137
Project Officer
John N. English
Wastewater Research Division
Municipal Environmental Research Laboratory
Cincinnati, Ohio 45268
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Municipal Environmental Research
Laboratory, U.S. Environmental Protection Agency, and approved for publica-
tion. Approval does not signify that the contents necessarily reflect the
views and policies of the U.S. Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorsement''or
recommendation for use. - :
11
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FOREWORD
The'U.S. Environmental Protection Agency was created because of increas-
ing public and government concern about the dangers of pollution bo the
health and welfare of the American people. Noxious air, foul water, and
spoiled land are tragic testimonies to the deterioration of our natural
environment. The complexity of that environment and the interplay of its
components require a concentrated and integrated attack on the problem.
Research and development is that necessary first step in problem solution;
it involves defining the problem, measuring its impact, and searchxng for
solutions. The Municipal Environmental Research Laboratory develops new and
improved technology and systems to prevent, treat, and manage wastewater_and
solid and hazardous waste pollutant discharges from municipal and community
sources, to preserve and treat public drinking water supplies, and to minimize
the adverse economic, social, health, and aesthetic effects of pollution.
This publication is one of the products of that research a.nd provides a most
vital communications link between the researcher and the user community.
This report describes water-quality impacts associated with wet-weather
discharges into the Chattahoochee River at Atlanta, Georgia, and details the
contribution of combined sewer overflows and other nonpoint discharges to the
impact. Through this project, data are being obtained to determine in a
rational way the degree of national wet-weather pollution control required.
Francis T. Mayo, Director
Municipal Environmental Research
Laboratory
iii
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ABSTRACT
I , '
The objective of this study was to assess the impact of stormwater run-
off on the water quality of receiving streams in the Atlanta area. The scope
included determining (1) the quality condition of discharges from 7 point
sources (waste-treatment facilities) and 13 nonpoint sources (streams) in the
study area of the Chattahoochee River basin during periods of stormwater run-
off, and (2) the relative impact of point and nonpoint storm discharges on
the quality of the Chattahoochee River downstream of the Atlanta Metropolitan
Area. Emphasis was placed on the collection of water-quality data in the
summer and autumn to determine the impact on streams from runoff produced by
thunderstorms during ^the dry-weather seasons. - .• • i
Compared to dry-weather flow, stormwater runoff significantly increased
the average concentration of suspended sediment, BOD5, total organic carbon,
total ammonia nitrogen, total phosphorus, fecal coliform bacteria, and trace
metals in most receiving streams in the Atlanta Metropolitan Area. Storm-
water runoff increased the mean concentration of most constituents 2- to 5-
fold. In most streams dissolved oxygen concentrations generally increased to
near saturation during periods of stormwater runoff.
The combined sewer overflow channels had mean BOD concentrations that
ranged from 23 to 37 milligrams per liter and fecal coliform concentrations
that ranged from 250,000 to 550,000 colonies per 100 milliliters.
During low flow in the Chattahoochee River, thunderstorms that occur in
the summer seem to have a much greater impact on river quality than storms at
other times of the year. The dissolved-oxygen concentration in- the Chatta-
hoochee River near Fairburn reached a low of 1.5 milligrams per liter (a 4-
milligram per liter decrease) as a result of runoff from a July thunderstorm.
This compared to a low of about 6.0 milligrams per liter (a 1.0-milligram per
oner,^e!rreaSe) an October thunderstorm and 6.8 milligrams per liter (a
2.0-milligram per liter decrease) for a frontal-type storm in November 1976.
Low flow in the summer and autumn occurs only about 21 percent of the
time due to river flow regulation by Buford and Morgan Falls Dams. The
flushing and diluting effect of water released by these dams causes a sig-
nificant improvement in Chattahoochee River quality most of the time.
This report was submitted in partial fulfillment of Interagency Agree-
ment No. EPA-IAG-D6-0137 by the U.S. Geological Survey, Georgia District
Office, under the sponsorship of the U.S. Environmental Protection Agency
The report covers the period of October 1975 to October 1977. :
IV
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CONTENTS
ill
Foreword , iv
Abstract ........<••«••••••••• ^
Figures ...... • .........••• ^__
Tables ^
Conversion Factors . • ' ' ^
Abbreviations and Symbols. ......•«• -^
Acknowledgments.
1. Introduction • ^
Previous studies •
Obj ectives and scope •
2. Conclusions
3. Description of Study Area
Point and nonpoint sources .... ........
Land use "
Hydrology. ;' * * 8
Water use. •, ••• • • • .
4. Methods of Data Collection and Analysis .......••«•• j-
Data collection • • -
Sample collection and handling 1J
Analytical methods •
5. Results of the Study
Quality, of nonpoint sources. • • ' '.'
Quality of point sources
Transport of pollutants in urban streams ......•••• W
Impact of stormwater runoff on stream quality. ....... -^
Clear Creek and Tanyard Branch combined sewer overflow. . JJ
- Peachtree Creek • ' '
Chattahoochee River . . • -20
Point- and nonpoint-source pollutant loads. . Jo
Impact of stormwater runoff on dissolved-oxygen
concentration • • '
References
50
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FIGURES
Number
1 Map showing location of study area and sampling sites in The
Chattahoochee River basin . .
2 Mean daily discharge for the Chattahoochee River at Atlanta
site for 1977 water year. .........
3 Concentrations and transport rates of constituents for
Peachtree Creek at Atlanta for a storm occurring on
November 27-28, 1976.
4 Concentrations and transport rates of constituents for Peachtree
Creek at Atlanta for a storm occurring on July 25, 1977
5 Concentrations and transport rates of constituents for Peachtree
Creek at Atlanta for a storm occurring on October 8-9, 1977
6 Concentrations and transport rates of constituents for Peachtree
Creek at Atlanta for a storm occurring on October 25, 1977.
7 Dissolved-oxygen concentrations in the Atlanta-to-Frariklin
reach of Chattahoochee River during low-flow period
June 1-2, 1977. ?........'..„ '•
8 Daily rainfall in Peachtree Creek basin, mean daily discharge :
at Peachtree Creek at Atlanta, and mean daily discharge and
daily minimum dissolved-oxygen concentration at Chattahoochee
River near Fairburn, 1977
• 9 Impact of stormwater runoff and hydropulse water on specific
conductance and dissblved-oxygen concentration at Chattahoochee
River near Fairburn, November 27-December 1, 1976.
10 Impact of stormwater runoff on specific conductance and
dissolved-oxygen .concentration at Chattahoochee River near
Fairburn, October 8-10, 1977
11 Impact of stormwater runoff and hydropulse water on specific
conductance and dissolved-oxygen concentration at Chattahoochee
River near Fairburn, July 25-27, 1977. ...
10
37
38
39
40
44
45
46
47
48
VI
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TABLES
Number
Map reference number, site name, and site identification number
of data collection sites in the study area. • • • • • • • • •
2 Flow design and mean daily flow of point sources for 1976 . . .
3 Land use for basins in the study area ... „-....
4 Mean concentrations and ranges of selected water-quality para-
meters for streams in study area during periods oJ: dry-weather
flow and stormwater runoff, October 1975-October 1977
5 Mean concentrations and ranges of selected water-quality para-
meters for the combined sewer overflow sites during periods
of stormwater runoff, October 1975-October 1977 . . .... •
6 Mean concentrations and ranges of selected water-quality para
meters for sites on the Chattahoochee River during periods of
dry-weather flow and stormwater runoff, October 1975-
October 1977. . . . . .
7 Range of concentrations of selected organochlorine insecticides
and industrial wastes for streams in the study area,
1976-1978 •••••*
8 Range of concentrations of selected toxic organic constituents
for streams in the study area, 1976-77. ...........
9 Mean concentrations and ranges of selected water-quality para-
meters for effluent from waste-treatment facilities in the
study area, March 1976-October 1977 .
10 Concentrations of selected organic constituents in the effluent
of waste-treatment facilities during storm period in
November 1976 ....,...••«
11 Comparison of dissolved and suspended concentrations of para-
meters expressed as percentage of total concentration for
selected sites in the study area. .
Page
5
7
9
15
21
23
26
28
29
31
32
vii
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TABLES
Number
12
14
15
Time distribution of selected constituent concentrations at
Clear Creek and Tanyard Branch combined sewer overflows for
a storm on March 12-15, 1976, and September 19, 1977
Characteristics of storms and antecedent conditions for the
Peachtree Creek basin
Computed constituent loads and percentages of loads contributed
by tributaries to the Chattahoochee River for a storm on
November 27-29, 1976. .......
Computed constituent loads and percentages of loads contributed
by tributaries to the Chattahoochee River for a storm on
October 8-9, 1977
Page.
34
35
42
42
viii
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CONVERSION FACTORS
For those readers who may prefer to use U.S. .customary units rather than
metric units, the conversion factors for the terms used in this report are
listed below: ,
Multiply metric unit
kilogram (kg)
kilometer (km)
liter (L)
millimeter (mm)
square kilometer (km2)
2.205
0.6214
0.03531
0.03937
0.3861
To obtain U.S. customary unit
pound (Ib)
mile (mi)
cubic foot (ft3)
inch (in.)
square mile (mi2)
,= 9/5°C + 32 or °C = 5/9 (°F - 32)
ix
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LIST OF ABBREVIATIONS AND SYMBOLS
ABBREVIATIONS
BOD 5
°C
°F
CSO
col/lOOmL
DO
ft3/s
kg
L
mg/L
mi2
jLimhos/cm
WTF
• 5 day biochemical oxygen demand
• degrees Celsius
• degrees Farenheit
• combined sewer overflow
colonies per 100 milliliters
dissolved oxygen
cubic foot per second
kilogram
liter
milligram per liter
square mile
microgram per liter
micromhos per centimeter
waste treatment facility
SYMBOLS
NH3-N
N02+N03-N
02
0-PO^
P
Ammonia nitrogen
Nitrite plus nitrate nitrogen
Oxygen
Orthophosphate
Phosphorus
Less than
x
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ACKNOWLEDGMENTS
The author acknowledges the Chattahoochee River Project personnel for
their assistance and advice on the project. Also, thanks go to the forecas-
ters of the National Weather Service at Atlanta who provided weather inform-
ation to aid the sampling effort. . •
xi
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SECTION 1
INTRODUCTION
The Federal Water Pollution Control Act Amendments of 1972 and 1977
(Public Law 95-217) provide strict controls to protect and maintain the qual-
ity of the Nation's waterways. With increasing urban development and more
stringent water-quality standards for receiving streams, urban stormwater
runoff is recognized as a significant source of pollution.,
PREVIOUS STUDIES
Several studies in the Atlanta Metropolitan Area have been conducted to
identify and assess the seriousness of problems associated with runoff from
the urban areas. In 1970 an urban stormwater runoff study was conducted for
EPA (U.S. Environmental Protection Agency) (13). The study included sampling
CSO's (combined sewer overflows) and urban runoff from sites in the South
River basin (tributary to the Ocmulgee River). The study defined and evalu-
ated pollution sources in the upper South River basin. An. urban storm-runoff
sampling program conducted in 1973 for the city of Atlanta resulted in an
analysis of the cost effectiveness of treatment for various storm sizes and a
preliminary design of storage and treatment facilities (2). A study by Hoi-
brook and others (8) utilized data from previous studies and a current samp-
ling program to evaluate the impact of combined sewer overflows and storm-
water runoff in the Atlanta area. The results indicated that on an annual
basis, nonpoint sources (CSO's and urban runoff) contributed about 45 percent
of the BOD (biochemical oxygen demand) load and about 95 percent of the
suspended-solids load to Metropolitan Atlanta streams.
More recently a river-quality study of the upper Chattahoochee River
basin was conducted by the U.S. Geological Survey (3). An assessment of the
nature, magnitude, and effects of discharge of point and nonpoint sources of
pollutants from the greater Atlanta area was included as part of this study.
Average annual constituent loads and loads from one storm in March were used
to assess the impact of point and nonpoint discharges to the Chattahoochee
River. Results of the study showed that on an average annual basis and du-
ring one storm in March 1976, nonpoint-source loads of dissolved solids,
total nitrogen, and total lead were larger than point-source loads at a
station located about 64 river kilometers (40 river miles) downstream of
Atlanta. However, dry-weather flow point discharges contributed the great-
est percentage of the pollutant load.
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OBJECTIVES AND SCOPE ' "
Data collection for this study, conducted by the U.S. Geological Survey
in agreement with the U.S. Environmental Protection Agency, was completed in
October 1977. The objective of the project was to assess the impact of
stormwater runoff on the water quality of receiving streams in the Atlanta
area. The scope included determining (1) the quality condition of.discharges
from 7 point sources (waste-treatment facilities) and 13 nonpoint sources
(streams) in the study area of the Chattahoochee River basin during periods
of stormwater runoff, and (2) the relative impact of point and nonpoint storm
discharges on the quality of the Chattahoochee River downstream of the
Atlanta Metropolitan Area. Emphasis was placed on the collection of^water-
quality data in the summer and autumn to determine the, impact to streams from
runoff produced by thunderstorms during the dry-weather seasons.
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SECTION 2
CONCLUSIONS
Variability of quality conditions in streams in the study area during
both dry weather and wet weather was high. In general, the water quality of
streams tributary to the Chattahoochee River was degraded during periods of
stormwater runoff. In most receiving streams, significant increases occur-
red in the mean concentration of suspended sediment, BOD5 (5-day biochemi-
cal oxygen demand), total organic carbon, total ammonia nitrogen, total
nitrite plus nitrate nitrogen, total phosphorus, fecal coliform bacteria,
and trace metals. •
Peachtree, Proctor, Woodall, and Nickajack Creeks consistently showed
the greatest impact from stormwater runoff. In addition to overland runoff
from storms, the water quality of Peachtree and Proctor Creeks was also de-
graded by discharges from the CSO's. Woodall Creek is heavily impacted_by
runoff from a small, highly urbanized basin and Nickajack Creek may be im-
pacted by discharges of untreated or partially treated sewage from a WTF
(waste-treatment facility) during periods of heavy stormwater runoff._ Dis
solved oxygen (DO) concentrations remained high in streams during periods of
stormwater runoff; therefore, no significant effects on^DO can be related to
urban runoff based on the number of measurements that were made during the
study period. The concentrations of constituents from the CSO discharges
were relatively high and comparable to the concentrations observed at the
Proctor and Woodall Creek sites. The CSO sites had extremely poor sanitary
quality as indicated by fecal coliform concentrations which often exceeded
1 million col/100 mL (colonies per 100 milliliters). DO concentrations
however were near the level of saturation even though the high BOD5 values
indicated a potential for creating low DO concentrations.
In general, the water quality of the Chattahoochee River during dry-
weather flow was good at the Atlanta site and relatively poor at the Fairburn
and Whitesburg sites. At the Fairburn and Whitesburg sites, the mean total_
:ammonia and nitrite plus nitrate nitrogen concentrations were greater during
dry-weather flow than during stormwater runoff. At the Fairburn site, the
mean total phosphorus concentration was also less for wet-weather flow as
indicated by a nearly 2-fold decrease in the mean concentration at-dry
weather flow. Data indicate that stormwater rather than water released by
Buford Dam was primarily responsible for dilution of these constituents at
the Fairburn and Whitesburg sites.
Generally, concentrations*of insecticides, industrial wastes and toxic
constituents in samples collected from point and nonpoint sources during
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times of stormwater runoff were low or less than the level of detection Of
^' ^ °CCUrred ±n the MgheSt concentration followed
chromium- The average concentration of lead in most
u/ r fi0dS °f stormwater runoff exceeded the criterion of
ug/L recommended for domestic water-supply by the EPA (12).
t0 be transported predominantly in the suspended
n, P Percentage of phosphorus is also transported as suspended
as ssol^d r^r %' ****** Percent^es of '^ic «rbon are transported
as dissolved rather than as suspended organic carbon. Inorganic nitrogen is
transported almost entirely in the dissolved phase. nitrogen is
loadsdu™ .; balanCe °f discharge volume and constituent
loads during a storm period in November 1976 and October 1977 showed that
203±r% ^ (WMCh reCeiV6S
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SECTION 3
DESCRIPTION OF STUDY AREA
The study area includes about 1,580 km2 (980 mi2) of the Chattahoochee
River basin between the Atlanta and the Whitesburg sites. The city of
Atlanta, which has a population of 1.5 million, is at the upstream end of
the study area. Rainfall averages about 1,300 mm (50 in.) per year and the
annual air temperature averages about 16°C (61°F). Figure 1 delineates the
study area and shows the location of sample sites and Table 1 lists the cor-
responding reference numbers, site names, and site, identification (U.S. Geo-
logical Survey) numbers.
TABLE 1.—MAP REFERENCE NUMBER, SITE NAME, AND SITE IDENTIFICATION NUMBER
OF DATA' COLLECTION SITES IN THE STUDY AREA
Map reference Site
number name
Site identification
number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
Chattahoochee River at Atlanta 02336000
Cobb Chattahoochee WTF near Atlanta 02336021
North Fork Peachtree Creek Tributary (Meadowcliff
Drive near Chamblee) 0233.6090
North Fork Peachtree Creek at Buford Hwy. near Atlanta 02336090
South Fork Peachtree Creek at Atlanta 02336250
Clear Creek at Piedmont Park at Atlanta (CSO) 02336274
Tanyard Branch at 26th Street Extention
at Atlanta (CSO) ; 02336290
Peachtree Creek at Atlanta 02336300
Woodall Creek at DeFoors Ferry Road at Atlanta 02336313
Nancy Creek Tributary near Chamblee 02336339
Nancy Creek at Randall Mill Road at Atlanta 02336380
R. M. Clayton WTF at Atlanta , 02336450
Hollywood Road- WTF at Atlanta 02336523
Proctor Creek at SR 280 at Atlanta ', 02336526
U.S. Air Force Plant 6 outfall near Smyrna 02336537
Nickajack Creek at Cooper Lake Drive near Mableton 02336610
South Cobb Chattahoochee WTF .near Mableton . 02336651
Utoy Creek WTF near Atlanta ' 02336653
North Fork Utoy Creek at Beecher Road at Atlanta ,(CSO) 02336654
Camp Creek WTF near Atlanta 02337073
Camp Creek at Enon Road hear Atlanta 02337116
Chattahoochee River (SR 29) near Fairburn . 02337170
Chattahoochee River (U.S. Alt. 27) near Whitesburg 02338000
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CHATTAHOOCHEE
RIVER BASIN
INDEX MAP OF GEORGIA
^-
/ A
EXPLANATION; ,
Stream, sampling site "•"•:
^"Stream gaging site ,_;
• Combined sewer overflow site
• Waste-treatment, facility
10
15
20
25
30 MILES":
1 1 1 1 1
-
Illl) 1 1
D 5 10 15 20 2
1
5 30 3
5 4
0 4
" * i ' _
5 KILOMETERS
Figure I.— Location of study area and sampling sites in the Chattahoochee
River basin. '
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POINT AND NONPOINT SOURCES
Twenty-one sites were established in the study area at which samples
were collected and flow measurements were made to determine the quality and
quantity of point and nonpoint discharges from the Atlanta Metropolitan Area.
An additional two sites on the Chattahoochee River near Falrburn and at
Whitesburg were established to monitor the impact of these point and nonpoint
discharges. The point sources are discharges from seven WTF's, which all
discharge into the Chattahoochee River or its tributaries in the Atlanta-to-
'Falrburn reach. The design flow and mean daily flow (1976) for each of the
point sources are given in Table 2. The R. M. Clayton WTF is the largest
point source of treated sewage discharging to the Chattahoochee River.
TABLE 2,—FLOW DESIGN AND MEAN DAILY FLOW OF POINT SOURCES FOR 1976
Map reference
number
2
12
13
15
17
18
20
Facility
Cobb Chattahoochee WTF near Atlanta
R. M. Clayton WTF at Atlanta
Hollywood Road WTF at Atlanta
U.S. Air Force Plant 6 WTF near Smyrna
South Cobb Chattahoochee WTF near Mableton
Utoy Creek WTF near Atlanta
Camp Creek WTF near Atlanta
Flow
design
(L/s)
450
5,270
65
310
340
1,300
650
Mean daily
flow
(L/s)
424
3,340
65
74
368
595
193
The combined mean daily flow from these facilities in 1976 was about
5 060 L/s (179 ft3/s), or 4 percent of the mean daily river discharge of
about 1.274 x 105 L/s (4,500 ft3/s) at the Fairburn site. Nonpoint sources
of discharge include all sources other than the seven WTF1s. Nonpoint dis-
charges were sampled at 11 stream sites and 3 CSO (combined sewer overflow)
channels. The Atlanta site on the Chattahoochee River is considered as a
nonpoint source. It is upstream of the major pollutant sources of the
Atlanta urban area. Of the 11 stream sites, 7 are located in the Peachtree
Creek basin. Most of the basin is within the Atlanta city limits, and Peach-
tree Creek conveys the major portion of the drainage from the Atlanta urban
area.
Proctor Creek is a small stream adjacent to Peachtree Creek and this
stream receives discharges from North Avenue and Greensferry CSO's during
storms, and treated wastewater from the Hollywood Road WTF. The sample site
on Proctor Creek is downstream of the inflows from the North Avenue and
Greensferry CSO's and Hollywood Road WTF.
Nickajack Creek is located west of Atlanta. Its headwaters are .in the
residential area of Marietta. Upstream of the sampling site, U.S. Air Force
Plant 6 outfall discharges treated wastewater to the stream.
Camp Creek lies southwest of Atlanta. Camp Creek WTF is located near
the mouth of this stream. The sample site is upstream of the WTF.
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Clear Creek and Tanyard Branch, located in the Peachtree Creek basin
and the North Fork of Utoy Creek, located in the Utoy Creek basin, werle samp-
led when the CSO's overflowed. The sampling sites were located in concrete
channels several hundred feet downstream from the point of overflow. 'Three
other CSO's in the study area whose drainage are about 6.5 km2 (2.5 mi2) 3 1
tanZ(1.2 mi2), and 2.3 km2 (0.9 m±2) were not sampled. Manpower limitations'
and difficulty of access to these sites were reasons 'why they were no* samp-
led. Constituent concentrations from these discharges are probably similar
to the CSO's that were sampled; however, constituent loads may be less: be-
cause of the smaller drainage areas. i
I
I
During dry-weather periods, interceptors located in the combined sewers
convey wastewater to nearby WTF's, During wet weather, wastewater plus the
additional stormwater spills over the overflow regulator into the CSO chan-
nels which discharge into nearby Peachtree or Utoy Creeks. i
-1.
LAND USE :
Land use in the study area is primarily urban, agricultural, and fores-
ted. Land-use and drainage areas of the subbasins within the study area are
listed in Table 3. Upstream of Metropolitan Atlanta at the Chattahoochee
River at Atlanta site, runoff is mostly from forested land. Between the
Atlanta and Fairburn sites (sites 1 and 22 in Figure 1) the drainage area
increases by 1,580 km2 (610 mi2). in this reach the Chattahoochee River re-
S!!:rIeVrba? JUn°fo fr°m the Atlanta Metropolitan Area. Between Fairburn and
Whitesburg (sites 22 and 23 in Figure 1), runoff originates from primarily
forested land. :
HYDROLOGY ;
The flow of the Chattahoochee River in the study area is dependent upon
rainfall and on regulation by the Buford and Morgan Falls Dams. A hydrograph
of the mean daily discharges at the Atlanta station for the 1977 water 'year
is shown in Figure 2. The highest flows generally occur in the spring 'and
the lowest flows in late autumn. Generally, the regulation schedule provides
tor peak hydroelectric power generation during the weekdays, which produces
relatively high average daily flows. Curtailment of peak-power generation
during weekends results in low flows in the river, provided there is no1
stormwater runoff. j
WATER USE - - . '
r
The water of the Chattahoochee River is utilized for power generation
water supply, wastewater assimilation, and recreation. ; '
Three fossil-fuel thermoelectric powerplants and 'two peak-power hydro-
electric generating facilities (Buford and Morgan Falls Dams) are located up-
stream of the study area. Average daily municipal water-supply withdrawals
L/s (134 ft^/s) all occur between Atlanta and Fairburn and treated
t,-,« *_3/ f^ (., waste-treatment facilities contribute an average of 5,060 L/s
(179 ft3/s) daxly to the river in the Atlanta-to-Fairburn reach. !
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TABLE 3.—LAND USE FOR BASINS IN THE STUDY AREA
[Data from Land Information Analysis Office,.Reston, Va. Percent values
are land use in drainage basin upstream of sampling site.J
,
Sampling site
Chattahoochee River
•at Atlanta, Ga.
(02336000)
North Fork Peachtree
Creek Trib. (Meadow-
cliff Dr. nr. Chamblee
North Fork Peachtree
Creek at Buford Hwy.
nr. Atlanta, Ga.
South Fork Peachtree
Creek at Atlanta, Ga.
(02336250)
Clear Creek at
Piedmont Park
at Atlanta, Ga.
Tany'ard Branch at
26th St. Extension
at Atlanta, Ga.
Peachtree Creek
at Atlanta, Ga.
(02336300)
Woodall Creek at
DeFoors Ferry Rd.
at Atlanta, Ga.
Nancy Creek Tributary
: (West Nancy Creek
Dr.) nr. Atlanta,
Nancy Creek at
Randall Mill Rd.
at Atlanta, Ga.
(02336380)
Proctor Creek at
State Route 280
at Atlanta, Ga.
Nickajack Creek at
, Cooper Lake Dr..
nr. Mableton, Ga.
North Fork Utoy Creek.
at Beecher Rd. at
Atlanta, Ga.
Camp Creek at Enon
Road nr. Atlanta,
i Ga. (02337116)
Chattahoochee River
nr. Fairburn, Ga.
(02337170)
Chattahoochee River
nr. Whitesburg,
.Ga. (02338000)
T
Drainage
area
(km2)t:
3,760
0.83
88.3
76.7
9.6
9'.1
225.
8.0
8.5
90.1
• 40.1
44.0
-
83.3
5,340
6,290
Percent
urban
t-t
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n .
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0)
& <
21.1
84
43.5
55.6
39.3
26.3
50.7
16.1
26.5
57.6
55.4
54.3
65.0
35.5
29.3
3.5
and
services
3.1
-
8.5
8.3
43.3
44.9
11.1
3.9
9.9
7.0
5.4
5.1
3.0
4.3
3.4
0.5
Industrial
0.7
-
1.8
1.4
-
7.1
1.6
-
1.0
9.6
-
-
0.6
0.6
-
iransportatlon
• and
Communicatior
1.2
' -
5.4
2.4
3.5
8.3
3.7
13.5
10.2
1.6
4.2
-
2.5
2.3
-
Other urban
2.0
-
11.6
8.2
13.9
12.6
10.9
58.2
-
9.0
7.6
0.8
32.0
0.9
4.1
0.1
Total urban
28.1
-
70.7
75.9
100.0
99.2
78.0
91.6
46.5
76.2
82.2
60.2
100.0
43.8
39.7
4.1
agriculture
d v
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5 ft
11.2
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0.1
0.2
-
0.1
-
1.0'
0.8
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5.5
2.9
5.3
16.5
Other
agriculture
-
-
-
-
-
-
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-
-
-
-
-
-
-
-
Total
agriculture
11.2
-
0.1
0.2
-
-
o.i
-
' 1.0
0.8
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5.5
2.9
5.4
16.8
Percent forested
54.4
16
25.2
22.5
-
0.8
19.8
8.4
46.3
20.5
15.2
29.5
49.1
51.5
75.4
Percent barren
land
5.6
—
3.4
1.3
-
-
1.8
~
6.3
1.5
2.1
3.6
2.7
2.9
3.0
1 Percent water
0.7
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0.1
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0.3
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1.0
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0.6
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a
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The reach-of the Chattahoochee River between the confluence of Peachtree
Creek, about 4.0 km (2.5 mi) downstream of the Atlanta station, and Cedar
Creek, 2.4 km (1.5 mi) upstream of the Whitesburg station, is classified as
fishing water by the Georgia Department of Natural Resources, Environmental
Protection Division. An average daily DO (dissolVed-oxygen) concentration of
5.0 mg/L and no less than 4.0 mg/L is required at all times, when the river
flow measured at a point immediately upstream from Peachtree Creek equals or
exceeds 21.2 x ID1* L/s (750 ft3/s), unless violations occur due to uncontrol-
led urban stormwater runoff or discharges from CSO's to the river, or both
(5).
11
-------
SECTION 4 r
METHODS OF DATA COLLECTION AND ANALYSES
DATA COLLECTION
t
The data presented in this report were collected by the U.S. Geoi.ogical
Survey between September 1975 and November 1977. The collection of data,
specifically as part of the EPA stormwater runoff study, began in November
1976 and was completed in October 1977. During this period, flow and;water-
quality measurements were made at 13 stream sites in the study area during
stormwater runoff events. At some of these sites, samples were collected
over the storm-runoff event to define stream-quality characteristics during
various stages of stormwater runoff. The quality of effluent from was;tewater
treatment facilities that discharge into the Chattahoochee River was summar-
ized from data collected by the U.S. Geological Survey and from available
flow and water-quality data obtained from treatment plant monitoring records.
i
i
Parameters determined in this study include DO, specific conductance,
temperature, ammonia, nitrite, nitrate and organic nitrogen, phosphorus, or-
ganic carbon, BODs, suspended inorganic sediments, trace metals, organochlo-
rine pesticides, fecal coliform and fecal streptococci bacteria, and s'elected
industrial pollutants (benzedine, trichlorethylene, chloroform, bromocihloro-
methane, dibromochloromethane, bromoform, carbon tetrachloride, and 1,2-
dichloroethane).
• . i
Stream constituent loads for the stormwater runoff periods of November
27-30, 1976, and July 25-27, October 8-10, and October 25-27, 1977, we're
determined by calculating the area under the transport rate (instantaneous
load versus time) curve for the duration of the storm. The transport rate
curve was developed by drawing a smooth curve through the instantaneous load
values which were calculated by multiplying constituent concentration itimes
the stream discharge at time of sample collection.
Point-source constituent loads for the November 1976 and October 1977
storms were computed by multiplying the product of the mean constituent con-
centration and the mean of the daily discharges for the storm-runoff period
by the length of time it took the stormwater to pass the Fairburn site. The
assumption was made that constituent concentrations and flows from' the i point
sources were uniform during the storm period. Data indicate that this
assumption was reasonable. If the WTF became hydraulically overloaded! during
a storm, the untreated water that bypassed the facility was considered!a non-
point source. These sources were not sampled. ;
12
-------
The total point-source load to the river was computed by summing the
loads from each of the treatment facilities. The point-source constituent
concentrations were approximated by using the mean concentrations determined
from spot samples collected by the U.Se Geological Survey in 1976-77. Plant
discharges for the storm period were obtained from plant operator reports
supplied to the Georgia Environmental Protection Division,,
SAMPLE COLLECTION AND HANDLING
Stream samples were collected in accordance with techniques described by
the U.S. Geological Survey (9). Depth-integrated samples were collected man-
ually at several.verticals in the stream cross section by use of a suspended-
sediment sampler. Samples were then composited in glass gallon bottles that
had been rinsed first with 10-percent hydrochloric acid and then with deio-
nized water. The samples were preserved by chilling until processed in the
laboratory. Several subsamples analyzed for various parameters were obtained
from each composited sample by use of a churn-type splitter. Samples ana-
lyzed for industrial pollutants, bacteria, and insecticides were collected
separately in the field and were not taken from the composited samples. BODs
and bacteria samples were analysed as soon as possible, usually within 12
hours after collection. The recommended 6-hour maximum holding time for bac-
teria was sometimes exceeded because of the length of time between sample
collection and delivery of the sample to the laboratory.
DO and temperature were measured at the time of sample collection with
an oxygen-temperature meter. At most.sites, stream discharge at the time of
sample collection was determined from stream stage and a predetermined stage-
discharge relationship. At the CSO sites, discharge^was measured continu-
ously with a current meter during the storm event. Sample sites at Atlanta,
Fairburn, and Whitesburg on the Chattahoochee River and Peachtree Creek at
Atlanta (Figure 1) have stream-stage recorders from which discharge was
determined. A water-quality monitor on the Chattahoochee River near Fairburn
provided hourly DO, temperature, pH, and specific-conductance data.
ANALYTICAL METHODS
Methods described by Skougstad and Greeson and others were used to ana-
lyze the samples for physical, chemical, and bacterial quality except for
BOD and special toxic materials (9) (7). BODs was determined according to
the unseeded sample methodology described in the American Public Health
Association's methods book, and the selected industrial pollutants were ana-
lyzed for according to EPA procedures in the^EPA laboratory in Cincinnati,
Ohio (1) (11).
13
-------
SECTION 5
RESULTS OF THE STUDY
The impact of stormwater runoff on the quality of a receiving stream
depends on the season of the year, the type of storm (whether a convective
thunderstorm or frontal storm), storm intensity, land use in the basiii,
topography, antecedent conditions, and for the Chattahoochee River, aihighly
regulated stream, the flow condition during stormwater runoff. As might be
expected, these factors result in stream-quality conditions that are highly
variable and difficult to predict. !
i
QUALITY OF NONPOINT SOURCES . ' ; '
Table 4 summarizes the physical, chemical, and bacteriological data for
tributaries to the Chattahoochee River collected during wet-weather and dry-
weather flow conditions. Variability of stream quality during both flow con-
ditions is very high, as indicated by the range of constituent concentra-
tions. Generally, the chemical quality of most streams sampled is good
during dry-weather flow. Exceptions are Woodall and Proctor Creeks, two
highly polluted streams that have relatively high concentrations of chemical
constituents. In contrast to the chemical quality, the sanitary quality of
the streams is poor, as,,indicated by the high dry-weather, .fe.cal cpliform bac-
teria concentrations. Dry-weather mean fecal coliform concentrations ;ranged
from 300 col/100 mL for the Nancy Creek tributary site.J:o JL30,OOQ col/100 mL
for the Woodall Creek site. , ,
Based on the water-quality parameters listed in Table 4, stormwater run-
off degrades the water quality of most streams that were sampled in the study
area.
Generally, DO concentrations in streams at the time of sampling were
higher during periods of stormwater runoff than at times of dry-weather flow.
For this reason, the detrimental effects of stormwater runoff on receiving
streams cannot necessarily be determined by DO measurements. Based on the
number of measurements that were made during the study period, no significant
detrimental effects on DO in the tributary streams to the Chattahoochee River
could be related to urban runoff. |
i
Parameters other than DO listed in Table 4 do, however, indicate (that
significant water-quality degredatipn occurs during periods of stormwater
runoff. Mean concentrations of suspended sediment, BODs, total organic car-
bon, and trace metals are greater for periods of wet weather than dry weather
for all streams listed in Table 4,. The suspended-sediment concentrations
14
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_ -,(02336610)
1
I
1
I
1
I
r-t
CO
J c
i m
Pu
Q
1
1
CM
CM
CO
O O
O O
sj O
r-{ 0
CM
Pi
CO
CO
C5.
J ^
bJ' C
i )-i i— i
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CJ CO
CO
0. ' (M
ss
18
-------
increase significantly during periods of stormwater runoff. The largest in-
creases in the mean suspended-sediment concentrations are at the Peachtree,
Nickajack, and Proctor Creek sites. Mean dry-weather suspended-sediment con-
centrations for the Peachtree and Nickajack Creek sites are 33 and 38 mg/L
compared to mean wet-weather concentrations of 780 and 1,100 mg/L, Dry
weather suspended-sediment data are not available for the Proctor Creek.site,
but the mean wet-weather concentration is 1,700 mg/L.
The concentration of suspended sediment in streams Is related to the
concentration of many constituents. Increases in many constituent concentra-
tions during periods of stormwater runoff are directly associated with in-
creases in suspended-sediment concentration in the streams. Faye and others
(4) demonstrated that, in general, suspended concentrations of phosphorus,
nitrogen, organic carbon, lead, zinc, copper, chromium, and arsenic correla
ted well with concentrations of suspended silt plus clay-size particles.
'"" The concentration of BOD5 showed large increases during periods of
stormwater runoff. The highest mean wet-weather BOD5 concentrations were at
the Peachtree, Woodall, and Proctor Creek sites where mean dry-weather con-
centrations of 1.9, 9.3, and 15 mg/L increased to mean wet-weather concentra-
tions of 13, 32, and 32 mg/L, respectively. Mean wet-weather total organic
carbon concentrations were relatively high at the Woodall and Proctor Creek
sites. Mean dry-weather concentrations of 9 and 13 mg/L increased to mean
wet-weather concentrations of 19 and 45 mg/L, respectively.
The mean concentrations of total ammonia nitrogen, total'phosphorus, and
fecal coliform bacteria were greater for wet-weather than dry-weather condi-
tions for most but not' all streams sampled. The highest mean wet-weather
Concentration of total ammonia nitrogen and total phosphorus was at the
Peachtree Creek site where mean dry-weather concentrations of 0.13 and 0.09
mg/L increased to wet-weather concentrations of 0.37 and 0.50 mg/L, respec-
tively. At the Woodall and Proctor Creek sites, stormwater runoff dilutes
the dry-weather concentration of total ammonia nitrogen and total phosphorus.
Mean dry-weather total ammonia nitrogen concentrations of 4.1 and 4.5 mg/L at
the Woodall and Proctor Creek sites.decreased to wet-weather concentrations
of 0 21 and 1.7 mg/L, respectively. Dilution of total £immonia nitrogen also
occurred during stormwater runoff periods at the North Fork Peachtree Creek
site. Similarly, at the Woodall and Proctor Creek sites, the dry-weather
mean total phosphorus concentrations of 2.0 and 2.3 mg/L were decreased
slightly by stormwater runoff. ;
The highest mean wet-weather concentrations of fecal coliform bacteria
were at the Peachtree, Proctor, and Nickajack Creek sites where mean dry-
weather concentrations of 33,000, 14,000, and 5,500 col/100 mL increased to
mean wet-weather concentrations of 140,000,-260,000, and 170,000 col/100 mL,
respectively.
The mean total nitrite plus nitrate nitrogen concentration did not
change significantly with the flow conditions for most streams. However, at
the Proctor and Nickajack Creek sites mean concentrations did show consider-
able, change. Compared to mean dry-weather concentrations, the wet-weather
19
-------
concentrations increased at the Proctor Creek site and decreased at the Nick-
ct J3.CK CrGGtC SltG •
The mean dissolved orthophosphate concentrations were 0.10 ing/L or less
for all stream sites sampled except the Woodall Creek site. At this site the
mean dry-weather concentration of 0.56 mg/L decreased to a mean wet-weather
concentration of 0.43 mg/L.
trac\metals determined in samples, lead values were the highest
hr ^-weather and wet-weather conditions followed by zinc, copper, and
chromium During dry-weather flow, the mean concentration of lead at 'most
a8T,beiOW 5°' Ug/L" A crlterion °f 50 ug/L is the maximum level
on , r f°r d°meStiC Water SUpply (12)' However> duri-g «t-
77 fn ?nS /T°nS ?? ^^ concentrati°» of lead for most sites ranged from
tratLi'o? Yfnn' */T ^ ^ 5° Ug/L criterion' The ^hest mean |concen-
"n ? *•£ TT' 2 T?g/L W3S at the Proctor Creek site. For all sampling sites
except the Woodall Creek site, the mean dry-weather and wet-weather cdncen-
t rations of zinc, copper, chromium, arsenic, and mercury did not exceed the
EPA recommended criteria for domestic water supply of 5 mg/L, 1.0 mg/L 50
ug/L, and 2.0 ug/L, respectively. The Woodall Creek site had a mean wet-
weather chromium concentration of 60 ug/L, which is 10 ug/L larger than the
JiFA maximum recommended criterion for domestic water supply.
In summary, data presented in Table 4 .Indicate that streams undergo
varying degrees of water-quality degradation during periods of stormwater
rr° 5' Jeachtree> Proctor, Woodall, and Nickajack Creeks consistently
showed the greatest impact from stormwater runoff. In addition to stoirmwater
runoff, both Peachtree and Proctor Creeks receive discharges from CSO's du-
ring storm periods that substantially .contributes to the quality degradation
of those streams. (See Peachtree Creek section.) Woodall Creek is heavily
impacted by runoff from a small, highly urbanized (92-percent urban) basin.
Nickajack Creek may be impacted by discharges of untreated or partially
treated sewage during periods of heavy stormwater runoff; however, specific
data are lacking to determine the source of pollution.
thP rh , Physical> Chemical and bacteriological dat for
the CSO channel sites collected during wet-weather flow conditions. Mean
concentrations of constituents in stormwater runoff from the three CSO [chan-
nels (Clear Creek Tanyard Branch, and North Fork Utoy Creek) were relatively
high and comparable to the mean constituent concentrations at the Proctor
Creek (which receives discharges from two CSO's) and Woodall Creek sites.
Fecal conform concentrations in the CSO channels are extremely high, o!ften
exceeding million col/100 mL in Clear Creek and Tanyard Branch compared to
counts of less than 400,000 col/100 mL in streams that do not receive CSO
discharges. DO concentrations are near the level of saturation.
siteon the physical, chemical, and bacteriological data for
sites on the Chattahoochee River for periods of dry-weather and wet-weather
X J.OW •
i
At the Atlanta site, which is upstream of the Atlanta Metropolitan Area
water quality is good. Mean constituent concentrations are low during I
20
-------
.,
u
z
cc.
•U.
C
CO
w
H
1-1
INED SEWER OVERFLOW S
TABTE 5 -MEAN "CONCENTRATIONS AND RANGES OF SELECTED WATER-QUALITY., PARAMETERS FOR THE COMB
J ' DURING PERIODS OF STORMWATER RUNOFF, OCTOBER 1975-OCTOBER 1977
- • [DWF - Dry-weather flow: SWR - Stormwater runoff]
j-
Z J
W 6C
ra E
j
-i
i c ^-
M C J
tl 6C
-i co E
1! 0 -^
j
irvJ!
o --
C CC
PC S
Suspended
sediment
(mg/L)
Dissolved 02
(mg/L)
aauBy
UBO^
pajduiBK
S3USAS uuoqs
sajduius
jo jaquinN
oSuuH
UBOU
poiduiuB
K3U.1AS UU03S
SO^duiBS
jo aoquinfj
aauBa
UB.1K
pOlUlUBS
KqU3A3 UUO3S
sa"[diuBS
|O joquinfj
oauua
UU.IH
p^^duiBS
sluoA.i uiaoas.
yo^diuus
jo a.iquniN
otiui.'M
UB.1W
p,i[diui;s
S3U.JAO U1J03S
so [ diuus
jo joqumN
(«/'!)
nou jo .lauua .
suojq jpuoo noiil
Sampling site
c
<
3
C
r-H
U_
o
"^.
t4
S
^
-JCN '
~>
0
vC
O
b.
o
"O Fu ^
Dissolve
as
(mg
Total phosphorus
as P
(mg/L)
Total N02+N03
as N
(mg/L)
I
UE3H
quaAO IUJ03S
jTSmij
— -
uuow
K3U,1A.T UU03S
jo'T^MM
aSuBy'
UBflK
pn LduilJK,
K3UOAO UU03S
jo aoquinfi
~
UE.H
pnjdiues
jo aBqiuiif}
nojj jo oSuaa
suoiqipuoo ^.o"[^i
Sampling Site
£
ol
i—!
X
CM
C
C
O
O
in
m
-
rH
moc
1
"
" C
c
CC
o
-
CO
i-H
M CC
D 0
' CO
o
CO
1
D O
0 'C
-t O
cr
Clear Creek at Piedmont
Park at. Atlanta Ga.
(02336274)
d
i— i
m
i— i
o
0
o
CM
-
vC
t-l
-4
j
CO
,— 1
^
c
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CC
rH
r^i in
C: O
CO
O
CO
1
in o
30 O
o
o
§
Tanyard Branch at 26th
Street Extension
at Atlanta ua.
£
o
o
o
vO
CM
0
O
C
m
CM
_
CC
r-H
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i-H
0
i-H
CO
c CM
i: o
m
C
,— i
CO
!M CO
D O
CO
o
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CO
1
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— r-
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CO
North Fork Utoy Creek
at Beecher .Road at
Atlanta, Ga.
(02336654)
21
-------
sa
*3
CO
01
iJ
"£
(fi
OC
c
-H
.-{
CL
1
C/3
QJ «"
•H CO
CU iJ
C
4J ffl
18 -H
Clear Creek
Park, at At
(02336274)
<^ 1 OJ ffl
" 1 ^
WC |O '
* o • -a
•H nj 1 > (TJ
JZ W C5 loo
u c u iS .
lanyard Bran
Street Exte
at Atlanta,
(02336290)
North Fork U
at Beecher ]
Atlanta Ga
(02336654)
0 tJ 01
H 0)3
£•
psjduiFS
jo
jo
JO
-------
'
r
E
Frf
g •
THE CHATTAHOOCHEE RI
977
ford Dam]
IAMETERS FOR SITES ON
3TOBER 1975-OCTOBER 1
water released by Bu
TABLE 6 -MEAN CONCENTRATIONS AND..RANGES OF SELECTED, WATER-QUALITY PA!
' DURING PERIODS OF DRY-WEATBER FLOW AND STORMWATER RUNOFF, 0
[DWF - Dry-weather flow; SWR1 - Stormwater runoff plus
nj g
3 •—
-t
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9
VSZ
°-s~a
H cd J3
n) o^-*
4-1
O
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^5
o M
«3
Suspended
sediment
(raB/L)
Dissolved 02
(mg/L)
SSUB^
UE3W
S3tdUlES
JU3A3 UUO5S
sstduiES
jo jsquinji
aSUBU
UB3R
sstduiBS
}U3AS U1JO5S
sa-fduiBS
jo jaqumN
aSuE^i
UBSK
ps^duiBS
S3U3A3 mao^s
sa^duiBs
jo aaqtunn
aSusH
UB3R.
sa^duiES
S3U3A9 UlIOHS
saxduiBS
jo aaqninfi
sSuB^i
UB3W
pajduiES
SJU9A3 UU03S
S3"[ CHUBS
jo asquinn
(s/1)
aofj jo aSusg.
SUOT^TpUOO MO-[£
OJ
4-1
•H
(fl
M
a
•H
c-H
O.
en
I
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OC
oc
c
c
?
vOCC
ovc
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f~-r~
tr
CT
i
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OH
00
vO
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i— I
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CM
1
tn
sD
CM
I
r^vQ
^100
-a-
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0
• CO
1
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<±^D
CO
in
CO
c^
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y IH c
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1
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Chattahoochee River ..
at Atlanta, Ga. •
(02336000)
i
^D i-
O co c*
O i-l C
m
o
p-
H en c
3 0 C
vO
0
0 CM
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i— t
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CM CM
CM
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o
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00
i-l CO
i-i r--
o
CO
CO
m
0
CM
1
i-t-vf
vOM
,-H
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CO
r-H
m
CM
; o c
DOC
J> . CO
i-H CO
vD
CM
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1
mo
<3-00
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in
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1
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-* ""
,-Tr
$ P
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3 C
3 H
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3 0
CM
O
0
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CM
3 00
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CO
CO
o
t iH
CM
CM
a\ IA
tH
r^
in
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CM
,-
aSuBfl
UESR
ps-tduiBiJ
sjuaAS raao:is
ssidmBS
jo aaqmnN
aSuea
UB3M
pa-[duiBS
s3uaAa raioig
S9"[d«JBS
jo asquinfi
sSuea
UBSW
psfduies
S3USA3 UiaC3S
SS|dUIE'S
jo aaqainn
sgUBVI
UB9K
SStdlllBSi '.
S3U3AS uiaojs
satduiBS
jo jaqmiifj
(s/1)
M01J JO 3§UBH
SUOTJTpUOD MOtJ
Sampling site
10
r^o
mc^i
CV)
O
0
VD
r~
1
O^H
00
OO
C
CNI
1-W3
OO
OO
n"
i-H
CM
0
1
0
m
i-H
,H
O
0
o
VO
CM
0
O
-a-
CM
-3-tH
iH-vT
OO
vD
CM
O
CM
tH
0
CO
io
00
COO
rHCO
^H
i— t
0"
Chattahoochee River
at Atlanta, Ga.
(02336000)
OC
CT\C
C
CT
C
0
0
CO
CO
u"
1
MDCO
CM
-------
Stormwater runoff plus water released by Buford Dam]
i
1-1
I
|
CJ
4J
S3
f
Q
1
Total '
arsenic
(W/T.1
Total
chromium
(uB/L)
03 Q.-^.
" Q* 00
O O D
E-i O ^-*
rH x-*
to o j
O tH 0
'is -o G"
O O 00
a§uBH
UE3W
S3U9A3 uuoqs
jo aaquinj;
3SUBH
UB9M
squsAa mjoqg
JO asquin^
93UBW
UE9J^
SIJU3A9 UlJtO^Q
jo .isquinN
33UEH
UB3K
patdoiBs
quaAS uuoqg
satduiBS
jo jaquinjj
aSuBH
UB3H
pa^duies
jo aaqmn^
«°Td jo 93uBH
Sampling site
i
rH
rH
i
n
o
CO
-
T
«
rH
r
0
rH
rH
1 -a- c
rH C
C
CM C
CM v
L
rH U
r
3 o i c
3 0 0 C
3 0 O C
o m •*- c
o co n r-
ir
r-i
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Chattahoochee River
at Atlanta, Ga.
(02336000)
) -T rH CM C
CM iH
m
•H -a-
1 ]
O in O in
vo r**
rH CM
in
vo m
rH
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CM rH
m
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rH
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-
c') t-H
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C'
CO CO
cs
-
CM rH
CM
§ '
CM
CO O
-
•
-------
dry-weather flow. As shown in Table 6, the greatest increases in mean wet-
weather concentrations are for suspended sediment which increased about 50-
fold, total phosphorus which increased 5-fold, and fecal eoliform bacteria
which increased about 7-fold.
At the Fairburn and Whitesburg sites, the mean total ammonia and total
nitrite plus nitrate nitrogen concentrations were greater during dry-weather
flow than for periods of stormwater runoff. The mean total ammonia nitrogen
concentrations^ 1.2 mg/L at the Fairburn site and 0.65 mg/L at the Whites-
burg site for dry-weather flow decreased to 0.36 mg/L and 0.23 mg/L for wet
weather flow. Similarly, the total nitrite plus nitrate nitrogen concentra-
tion of 0.74 mg/L at the Fairburn site and 1.1 mg/L at the Whitesburg site
for dry-weathe? flow decreased to 0.37 mg/L and 0.43 mg/L for wet-weather
flow At the Fairburn site, the mean total phosphorus concentration was also
less'for wet-weather flow, as indicated by a nearly 2-fold decrease in con-
centration from the dry-weather flow.
During dry-weather flow, concentrations of these constituents were
higher at the Fairburn and Whitesburg sites because of high ammonia and
nitrite plus nitrate nitrogen concentrations that are discharged from the
WTF's to the reach of the river between the Atlanta and Fairburn sites.
During wet weather, relatively lower concentrations of these constituents _
occurred in the river because of dilution by either stormwater or water re
leased by Buford Dam, or both. Data indicate that stormwater is primarily
responsible for the dilution because BOD5 and total organic carbon concen-
trations increased during wet weather. If water.released by Buford Dam
(which has low constituent concentrations) were primarily responsible for
the dilution, then all constituent concentrations would have decreased.
The concentrations of insecticides and industrial wastes in streams in
the study area were low or below the level of detection (less than 0 01 ug/L)
(Table 7). Unfiltered water samples were analyzed for aldrin, chlordane
endrin, lindane, heptachlor, heptachlor epoxide, DDD, DDE, DDT, and toxaphene
(insecticides) and PCS and PCN (industrial wastes). Organochlorine insecti
cides were more commonly detected in Peachtree Creek and Tanyard Branch
CSO's. A sample collected at low flow at the Woodall Creek site showed a PCB
concentration of 9 ug/L. Woodall Creek drains a small highly industrialized
land-use area (Table 3). -
Selected toxic organic constituents sampled at selected sites in the _
study area are shown in Table 8. Generally, concentrations of these organics
in nonpoint discharges were low and often below the level of detection Tri-
chloroethylene and chloroform were detected most frequently. Trichloroethy
lene occurred in the highest concentration. Concentrations of 15 23, and 2S
ug/L were detected in Clear Creek (CSO), Woodall Creek, and Tanyard Branch
(CSO), respectively.
QUALITY OF POINT SOURCES
The quality of effluent from seven WTF's is listed in Table 9. The mean
concentrations of constituents in the treated waste discharges from all WTF s
except the U.S. Air Force Plant 6 and Camp Creek treatment facilities were
25
-------
§
i
1
a«
II
u 3
z
3 «? TT
SW si
3
Si
OH =
O
W H *£
§5 1
W CO
w 5
SG w *a
sg 3
§"*
2- R
U CO
!3 £ B
ii „
i §
r*.
u
Q
g
RJ
•2
O
s
c
•H
J-.
rH
B -».
jo aaqmn
;.
jo jiaqum
§. _ 3 UBH
H jo jaquin
u aSiiBji -„
i
H sajduiBS
jo j.3 quint
!
-------
27
-------
3 -,
14
Sg 4>
1
5?
-------
TABLE 9.-MEAN CONCENTRATIONS AND RANGES OF SELECTED WATER-QUALITY PARAMETERS FOR EFFLUENT FROM WASTE-TREATMENT FACILITIES
: IN THE STUDY AREA, MARCH 1976-OCTOBER 1977
[WTF - Waste-treatment facility]
Sampling site
Cobb Chattahoochee
WTF near Atlanta,
Ga. (02336021)
R.M. Clayton WTF
at Atlanta, Ga.
(02336450)
Hollywood Road
WTF at Atlanta,
Ga. (02336523)
U.S. Air Force
Plant 6 outfall
near Smyrna, Ga.
South Cobb Chatta-
hoochee WTF near
Mableton, Ga.
Utoy Creek WTF
near Atlanta, Ga
(02336653)
Camp Creek WTF
near Atlanta, Ga
(02337073)
Range
of
low
L/s)
28D-
820
,800-
,500
57-
85
57-
310
110
570
400
790
110
1,100
Dissolved
°2
(mg/L)
samples • I
8
0
-
6
19
19
19
'
.8
.6
-
5.4
1.9
3.2
4.0
o
00
1
0.1-
2.7
0.5-
5.5
-_
1.5-
9.8
0.2-
9.5
2.3
6.3
3.1
7.0
BODS
(mg/L)
CO
a)
rH
(0
4
6
9
8
24
22
25
8
35
35
45
3
36
17
7.
(U
2.8-
175
0.2-
220
7.8-
87
0.2-
18
2.0-
110
4.3
37
1.7
45
Total
organic
carbon
(mB/L)
" samples
4
6
10
10
24
23
24
a
25
32
24
3.4
22
20
8.1
&
5.0-
88
11-
120
5.0-
44
1.8-
11
6.1
48
6.6
80
4.7
18
as N
(mg/L)
CQ
QJ
rH
1
CO
4
6
10
10
24
23
24
g
10
13
14
0.08
12
11
3.
a
3.6-
15
4.4-
18
10-
20
0.00-
0.41
1.2-
16
2.0
16
0.01
9.6
CD
tH
I
cd
CO
4
6
10
10
24
23.
24
as N
(mg/L)
§
.50
0.11
0.12
4.0
0.56
0.14
4.9
«
t:
cl
pi
.01-
2.9
0.00-
.2
0.01-
0.39
2.9-
0,00-
4.8
0.00-
1.7
0.24
13
phosphorus
as P
(mg/L)
Number of
samoles
4
26
10
10
24
23
24
§
£
.6
4.0
4.4
0.31
7.2
3.6
5.3
a)
00
c
0}
ta
1.1-
4.2
0.89-
11
1.6-
9.9
0.20-
0.50
1.4-
11
0.91
5.9
0.99
7.1
0-POi,
as P
(ma/L)
1 Number of
samples
8
9
9
9
9
9
9
I
•'
1.5
2.6
0.24
3.8
1.8
3.2
I
.01-
4.4
0.61-
2.5
1.3-
4.0
0.17-
0.38
1.7-
5.2
0.24-
3.1
2.0-
5.1
Sampling site
Cobb Chattahoochee
WTF near Atlanta,
Ga. (02336021)
R.M. Clayton WTF
•at Atlanta, Ga.
(02336450)
Hollywood Road
WTF at Atlanta,
Ga. (02336523)
U.S. Air Force
Plant 6 outfall
near Smyrna, Ga.
South Cobb Chatta-
hoochee WTF near
Mableton, Ga.
Utoy Creek WTF
near Atlanta, Ga
(02336653)
,Camp Creek WTF
near Atlanta, Ga
(02337073)
Range
of
low
L/s)
280-
820
1,800-
6,500
57-
85
57-
310
110-
570
400
790
110
1,100
Total
lead
(ug/L)
O V.
"s »
13 It
8
10
10
10
10
10
10
„
S
37
160
33
17
47
57
17
S
2-
94
35-
550
7-
100
7-
,50
14-
100
36
110
2
49
Total
zinc
(ug/L)
O 0
> E
Js "
8
10
10
10
10
10
10
d
53
94
460
43
29
84
72
41
a
f5
ta
20-
490
100-
1,600
20-
100
0-
120
30-
. 170
40
130
20
100
Total
copper
(ug/L)
a
at c
•a s
8
10
10
10
10
10
10
B
01
S
20
69
20
8
17
15
11
to
n)
3-
99
12-
200
7-
84
4-
16
6-
41
9-
28
4
18
chromium
(ug/L)
to
f)
* y
2;
7
0
10
10
9
10
10
S
s
28
20
19
41
21
26
18
CO
5-
60
10-
400
5-
50
5-
210
10-
40
10
60
5
50
CL
0) C
4
4
4
4
3
4
4
arsenic
(ug/L)
S
CD
1
5
1
°
1
1
1
0-2
3-6
1
0-1
0-2
0-2
1
1
mercury
(ug/L)
CQ
W I-t
"" S
a 55
D 10
SZ
2
2
2
2
1
2
2
§
35
.0
.9
0.6
0.2
0.2
0.1
0.1
CD
S
rS
0.1-
1.9
2.1
0.0-
1.1
0.1-
0.3
-
0.0-
0.2
0.1
0.2
cadmium
(ug/L)
CO
3 co
1
2
2
2
2
2
2
5
S
0
2
1
1
, 0
0
0
OJ
t>0
"
0^-5
0-1
0-2
0
29
-------
high. The ranges of the mean concentrations of some constituents lis'ted in
Table 9 (excluding the relatively low concentrations of U.S. Air Force Plant
- LrbL^To ?e?J ^/T8' WT 17 t0 45 m§/L B°D5' 2° t0 32 mS/L total '°W*e
carbon, 10 to 14 mg/L total ammonia nitrogen, and 3.6 to 7.6 mg/L total
phosphorus. t
Except for the R. M. Clayton WTF, the mean concentrations of trace
metals in the waste ef fluents , were , in general, less than the mean we't-
Tn3T M c°n^ntrations of .trace metals in the streams «100 ug/L) . As shown
p M if ' mean concentrati»ns of trace metals in the effluent from, the
R. M. Clayton WTF are 2 to 10 times greater than 'the other WTF' s. I
* • [
Point-source discharges were sampled one time during a storm event for
organochlorine insecticides and selected organic constituents. Insecticide
concentrations in all- samples were below the level .of detection, or occurred
only in trace amounts. Organic constituents were low (Table 10). Trichloro-
ethylene and chloroform were detected most frequently. Concentrations of
trichloroethylene ranged from les;s than the level of detection to 15 ug/L and
chloroform from less than the level of detection to 11 ug/L.
TRANSPORT OF POLLUTANTS IN URBAN STREAMS 1
Chemical pollutants that are transported by urban streams during ! storm-
water runoff have characteristic transport modes. They may be transported in
the soluble or particulate (suspended) phase, or both. The suspended pollu-
tants may occur as particulate organic material or be adsorbed onto tne inor-
ganic sediment particles. The mode of transport of, pollutants has signifi-
cant implication for allocation of resources for pollution abatement, i For
example, the constituents closely associated with suspended sediments ' as
opposed to the dissolved constituents, may be more effectively reduced in
urban streams by land use practices that control erosion, by street sweeping
and perhaps by pollution abatement measures such as retention ponds Sat col-
lect sediment. Table 11 lists the mean percentage concentration of selected
parameters in the dissolved and suspended phase for six sites in the study
3.3TG3. J
monlv H T *ndlcated ^ the mean Percentages, /occurs more1 com-
monly in the dissolved than in the suspended phase. The dissolved organic
carbon ranged from 46 to 65 percent. Exceptions are the Clear Creek So site
and the R. M. Clayton WTF. Samples from both of these sites had slightly
larger mean percentages of suspended organic carbon of 52 and 54 percent
respectively. Inorganic nitrogen (nitrite plus nitrate and ammonia nitrogen)
occurs mostly in the dissolved phase. Mean percentages ranged from 93*1° 98
percent Conversely, phosphorus and the selected trace metals occur pri-
ran«ed frof IsT^^ V^**' ^ ^ PercentaSe of suspended phosphorus
ranged from 45 to 98 percent. The overall mean percentage of suspended lead,
zinc, and copper ranged from 69 to. 96 percent. !
In summary the trace metals appear to be transported predominantly in
the suspended phase. A high percentage of phosphorus is also transported as
suspended phosphorus. Generally, higher percentages of organic carfare
30
-------
I H f-<
t 03 4J
O •—'
S ,
a
§
w
«'
iH ^1
>. t-i
>-S
%k s
^ O 01
0}
c! I *a
0 td -rH
^1 fcJ H
ra a) H
"«•§
i E
§ g
S1"
Dibrom-
chloro-
methane .
Bromo-
dichloro-
methane
Chloro-
form
Tri-
chloro-
ethylene
Benzidene
uQ-peitjuaouoo
ssjaiuyy
uoTpBa 3 uso uo 3
sa^draBS
uoT3B*3uaDU°3
S3~[ dines
jo aeqmnti
uo-p^Bainaouoo
sax dares
UOfgeJUUSOUOO
sajdmBS
30 aaqnmti
uo-p^Ea^ussuoo
s^i^sree
30 aaqranti
UOf3B.i:jUaOUO3
ssfdraes
jo jaqranft
Tio^aBaauaouoo
s3-[draus =
jo aaqrann
uof^BJ^uaouoo
saidmes
jo jtaqmnti
uof^'ea ^uaotioo
s&itfnxes
jo .isqumfi
0)
4J
1-J
CO
DO
i
rt
CO
V
-
CO
o
-
o
^^
g
-
i
~
g
-
i
-
o
eg
'-
g
- '
Q
E:
-
Cobb Chattahoochee
WTF near Atlanta,
Ga. (02336021)
V
-
Q
IS
1
i
-
o
CO
-
CO
0
-
g
-
CO'
o
-
vd
in
-
in ,
i— i
g
-
R.M. Clayton WTF
at Atlanta, Ga.
(02336450)
V
—4 •'
CO
O
-
i-
i
-
i
-
i
-
B
*O
-
g
-
South Cobb Chatta-
hoochee WTF near
Mableton, Ga.
fm
-------
g
8
co
ex.
o.
5
O
c
•H
N
O
Phosphorus
as P
z
O CO
•g "
a c
60 0)
§0
u
M 4J
•s
O
•gg
eg ,0.
CO M
0 0
assqd papuadsns
u-p rjuaojtad ueaj^
Uf rjuaoaad U'eajfl
sajdoiBS jo aaqnmjyj
papuadsns ueara :iU9oaa
osBud papuaduns
uf uuaoaad uwaw
«t>B4d paAxosufp
trp 3uao.zad ui;aj$
sa*[doiBs jo jajad UESH
UT »«S»d0^
s^tes 3° »«mt
papuadsns UBam rtuaojcad
aseqd papuadsas
UT w5^d°SS
S3TdraBs jo "qranM
papuadsns ueam rj.uao.iad
UT 3uao^ad UEOW
uj auaoaad UBOW
safdtnBs jo J9qtm^i
01
.u
•H
(0
g,
•H
•a
i
CO
CO
CO
CO
— i
a
CO
-H
CM
CO
CO
CM
-
VO
a
o
CM
CO
VO
CO
River at Atlanta,
Ga. (02336000)
-
CO
CO
Hi
<*
o
0
o
r*.
a
o
CO
CO
CO
{-.
CO
r- 1
CO
CM
CM
in
CO
near ureefc at
Piedmont Park,
at Atlanta, Ga.
(02336274)
3
CO
o\
VO
CO
0\
CM
vO
CO
vO
-3-
fx
a
s
CM
CO
«
-d-
vO
5
CM
CO
CO
vD
CO
26th St. Extn.,
at Atlanta, Ga.
(02336290)
CM
CO
CO
vD
CM
vD
VO
CO
3
tn
CM
2
CO
CO
CM
F-t
CM
CO
01
CO
3
00
CO
m
•*
vD
a\
CO
CO
crv
co
vD
1— I
at Atlanta, Ga.
(02336300)
CM
vO
CM
m
r-
CM
o\
vO
CO
CT\
VO
a
vO
.«
CM
CM
m
in
0
-
CM
CO
cr\
!^
m
vO
CM
at Atlanta, Ga.
(02336450)
CM
S
CM
2
CM
T— <
en
ON
m
o
s
en
\o
CO
o
0
CO
CO
CM
in
•*
vD
Cr»
CM
CM
CO
CM
CO
vO
CO
CM
River near
Fairburn, Ga.
(02337170)
32
-------
transported as dissolved rather than as suspended organic carbon. Inorganic
nitrogen is transported almost entirely in the dissolved phase.
IMPACT OF STORMWATER RUNOFF ON STREAM QUALITY
The Chattahoochee River downstream of the Atlanta site receives signifi-
cant pollutant loads from the highly urbanized (78-percent urban) Peachtree
Creek basin. Data from Peachtree Creek and the CSO's (Clear Creek and Tan-
yard Branch) indicate the quality characteristics of these discharges and
their impact on the quality of the receiving streams.
Clear Creek and Tanyard Branch Combined Sewer Overflows
Data collected from Clear Creek and Tanyard Branch characterize the
quality of water in the CSO channels. The time distribution of constituent
concentrations is shown in Table 12. For two storms occurring on March 12-
15 1976 and September 16, 1977, constituent concentrations generally were
highest during the rise of discharges and generally decreased by about one-
half during peak discharges. Most constituent concentrations increase
slightly during the last stages of the recession.
Because of the CSO's immediate flow response to rainfall, discharges
from Clear Creek and Tanyard Branch are received primarily during the rising
stage of the Peachtree Creek storm hydrograph. The impact of the CSO s on
Peachtree Creek and the Chattahoochee River will be discussed later in the
report.
Peachtree Creek
The nature of storms and perhaps antecedent conditions have a signifi-
cant effect on the quality of stormwater runoff and its impact on the re
ceiving waters. Stormwater runoff data collected during four different_storm
conditions describe the nature and magnitude of constituent discharges in
Peachtree Creek. Storm characteristics and antecedent conditions for the
four storms are listed in Table 13.
The hourly rainfall amounts, time, distribution of discharge, constituent
concentrations, and transport rates at the Peachtree Creek at Atlanta site
are shown in Figures 3, 4, 5, and 6. The November storm resulted from the
passage of a cold front which produced relatively continuous rainfall and
sustained runoff. The other 3 events resulted from thunderstorms with most
of the rainfall occurring during a 3- to 8-hour period. The resulting runoff
from the July and October storms was rapid and produced high peak flows.
The Peachtree Creek hydrograph is characterized by a minor peak in dis-
charge near the beginning for both the November and October storms. The bi
modal hydrograph can be attributed to the rainfall distribution and dis-
charges from the CSO's, which respond more quickly to rainfall than other
tributaries to Peachtree Creek. A similar peak is unnoticeable in the 'July
storm hydrograph, probably because of the short rainfall period.
33
-------
Si
•a
cu
I
cu
IH
CU
•§
D,
CU
O
CU
p.
CO
I
00
•H
5
•a
cu
co
co
cu
4-1
a>
S
o
o
e
to
rH O
CO MH c
CJ -H
CU rH -^
fa O rn
O C
rH
cd ro
4J CO
o cu
EH rH
CO
3
to
rH O PH
CO ft
4J O. CO
O CO CO
EH o
,C
o.
g
rH OOK
CO O
4-1 to CO
O 4J CK
H'd
CO
rH -H
to c a
4J O
o g co
H g o
CO
10
a
o
O
o
o
o
o
-3-
i-H
CM
O
00
•-*
o
o\
vO
-H VO
• CM
m
— 1 '
CM
CM
• m
to
*o
o
TJ
0)
CU
Clear Creek (Storr
-Rise-
Initial discharge
o
o
o
o
CM
CO
f"~l
en
o
00
-3-
O
oo
CO
-reaR-
25 minutes after
initial discharge
o
o
o
o
o
CM
CM
-3-
0
-3-
00.
O
00
CN
OO
2
-Kecession-
50 minutes after
initial discharge
o
o
o
o
CM
CM
-a-
CM
o
-d-
00
o
CM
*
CM
*
1
Kecession-
65 minutes after
initial discharge
o
0
o
vb
m
o
o
CM
CM
O
CO
r^
-H CN
-tf
rrT *
i-H
P.
CU CO
CO CM
O
•H
to
g.
e
to
O
Tanyard Branch (St
-Rise-
Initial discharge
o
8
0
o
m
i-H
1
rH
CM
CO
•
oo
•
vO
1
cu
CO
-Midpoint of ri
20 minutes after
initial discharge
o
o
o
o
-3-
m
l
CO
i-H
VO
•
CM
in
•
oo
CM
-wear peak-
30 minutes after
initial discharge
o
o
o
o
VO
CM
m
vo
o
oo
•
CO
m
•
*~H
CM
H
CO
-Midpoint or re
50 minutes after
initial discharge
o
o
o
o
0
i-H
1
c*
0
•— (
°).
CO
OO
.
-itecession-
_90 minutes- -af-ter,-^
initial discharge
34
-------
TABLE 13.—CHARACTERISTICS OF STORMS AND ANTECEDENT CONDITIONS
FOR THE PEACHTREE CREEK BASIN
Storm date
November 27, -1976
July 25, 1977
October"8, 1977
October 25, 1977
Duration
of Total
35
8
22
17
Antecedent conditions in
Peachtree Creek basin
Days since Approximate amount
rainfall rainfall last rainfall of last rainfall
(hrs) (mm) (-ma)
48
27
83
65
5
2
7
15
2
15
1
53
35
-------
Generally, constituent concentrations were greater during the rising
limb of the hydrograph and smaller on the receding limb for the July1 and
October storms. This characteristic was not apparent during the November
storm, during which the rainfall duration was long, initial runoff was
slower, and constituent concentrations were much more dilute. ,
I
The apparent effect of discharges from the Clear Creek and lanyard
Branch CSO's on the flow and constituent concentrations in Peachtree'Creek is
indicated by the relatively high concentrations of constituents that coincide
with the minor peak in discharge that occurred at the Peachtree Creek site
during the October 1977 storms. As shown in figures 3, 4, 5, and 6,ithe
maximum rates of transport coincided with maximum discharges, even though the
highest constituent concentrations often occurred prior to the maximum dis-
charges. Constituent concentrations, which were considerably higher'during
the July and October storms compared to the November storm, resulted in con-
stituent storm loads that were very much larger per unit volume than ithe
November storm loads. For example, the November storm volume was about four
times larger than the July storm volume, yet the November BOD5 and phosphorus
storm loads were only about twice as large as the July storm loads. ;Also,
the July ammonia nitrogen storm load was greater than the November ammonia
nitrogen storm load. Similarly, the October storm volume was roughly twice
the November storm volume, but storm loads in October ranged from 1 to about
6 times greater than the November storm loads. The higher constituent con-
centrations observed during the July and October storms can probably be
attributed to the rapid runoff, which had a greater capability to suspend and
wash material from the land surface than the less rapid runoff of thJ
November storm. [
Chattahoochee River j
Point- and Nonpoint-Source Pollutant Loads— i
n™,, ThS ™pact of stormwater runoff from the Peachtree Creek basin and ' the
WTF s on the Chattahoochee River was evaluated by an approximation of1 the
mass balance of discharge volume and constituent, loads during storm periods
that occurred on November 27-30, 1976, and October 8-10, 1977. A similar
analysis could not be done for the storm on July 25, 1977, because chemical-
quality data were not collected at the Chattahoochee River near Fairburn
site. Discharge volumes, constituent loads, and the percentage contribution
of the constituents to the Chattahoochee River near Fairburn are shown in
Tables 14 and 15. Losses due to deposition were not accounted for.
Many nonpoint sources to the Chattahoochee River were not measured dur-
ing these two storms. These nonpoint sources are primarily streams tributary
to the Chattahoochee River. (See Figure 1.) Unmeasured (residual) flow and
constituent loads in the Atlanta-to-Fairburn reach were computed as the dif-
ference between volumes measured at the Fairburn site and at sites upstream
of the Fairburn site, and as the difference between loads calculated for the
Fairburn site and for sites upstream of the Fairburn site. For example, as
shown in Table 14, the sum of the discharge volumes and constituent loads
™1? the Atlai*ta, Peachtree Creek, Nancy Creek, .and unmeasured sites and the
s equals the discharge volume and load at the Fairburn site. Clear Creek
36
-------
EXPLANAT ION
Concentration .transport rate
Cumulative rainfa
48 mm
I —i 1
Discharge volume
29 X I08 L
BOD5
Total load=22,000 kg
Total ammonia, as N
Total load =300 kg
Total nitrogen, as N
Total load =3500 kg
.Total phosphorus, as P
Total load = 720 kg
Total lead
Total load = 1200 kg
27
1200 0000 1300 0000
TIME, IN HOURS
28 29
NOVEMBER 1976
1200
30
Figure 3:—
Concentrations and transport rates of constituents for Peachtree
Creek at Atlanta for a storm occurring on November 27-28, 1976.
37
-------
EXPLANATION
Concentration Transport rate
25
30
CO o
50
0
2.0
Od 1.0
LJ
a.
CO
o
10
=!5.0
• 0
2.0
1.0
LU
o
o
o
2.8
1.0
Cumulative rainfall =
27 mm
«t9ri
Discharge volume =
6.8 X I08 L
BOD5
Total load = 12,000 kg
1000
I
Total ammonia, as N
Total load =380 kg
-B-OJL.
0
30
a
o
o
UJ
I
Total nitrogen, as N
Total load = 2800 kg
0
150
tr
UJ
a.
CO
1 T
Total phosphorus, as F3
Total load = 380 kg
' 1—
Total lead
Total load =350 kg
1200 0000 1200 0000
TIME,IN HOURS
25 26 27
JULY 1977
0
30
CE
z
<
oc.
2
CO
z
<
a:
30
I20C
Figure 4.—Concentrations and transport rates of constituents for Peabhtree
Creek at Atlanta for a storm occurring on July 25, 1977.
38
-------
E X P L AN A T I 0 N
RAINFALL, IN
MILLIMETERS
CL
U
"- — U"
_ to 150
~"-Ul —
ILLlZ
ot-o
CO— O
30
1
ul 2.0
1-
CC. 1.0
UJ
0.
CO
3 0
, IN MILLIGRA
Ul
3 b
DNCENTRATION
D S OC
0 .0
0.5
r
m uonc
H
: 1
M
\ _
1
i
i
• i
i i i 1
1 Cumulative rainfall - i
83 mm ~
- i i i 1
f\ Discharge volume =
/ \ 56 X I08 L 1 _
•/ ^- ' i ' ' l ' —
-i r 1 1 1 T
BOD5 £
A Total load =42,000 kg -
-r— ^ 1- 1 1 i
|\ Total ammonia, as N
1 \ Total load =1100 kg
lY Ira , ^>—- •<— 1 1_J
-T — — i -r 1 -T-.
A Total nitrogen, as N
/f]\ Total load =14, 000 kg ~
-i 1 r r— T—
1 Total phosphorus, as P
l li Total load = 3200kg
!'/l'k
ii'MNr- l
-1 — T 1 1 :
/\ Total lead
1 \ Total load = 1400 kg "
1/1 \v
Tf 1 1 rT 1- 1 1
2000
1000
o
o
0
UJ
CO
" Ul
a_
0 CO
50O 2
01
z
uT
0 ^
0 8 g
TRANSPORT R
- t>u
- 0
1200
0000
Figure 5 —
1200
TIME, IN HOURS
9 IO II
OCTOBER 1977
Concentrations and transport rates of constituents for Pe°cnt''ee
Creek at Atlanta for a storm occurring on October 8-9, 19 (f.
39
-------
E X PLANATION
Concentration •— Transport rate
2 CO t-
— CE
^UJ
j|
tcS 0
2 « I5°
la-o
oi-O
CO — O
S-'S o
50
n
Jlj 2.0
li-
ce i.o
UJ
0.
CO
So
< 10
s
o
I
Z
- 0
^ 1 0
o
<
I- 0.5
UJ
O
z
O 0
o i.o
0.5
o
_
. **&&$%
i | I
Cumulative rainfall =
65 mm
Irfli ' , 1 , -
f\ Discharge volume =
/ \ 47 X I08 L
/ x • "
- I x. -
-^ N^l— 1 i
r
— :
~o]ls'',
n/\. ,BOD5
¥ \ Total load = 69,000 kg ~
I ir^-^ i ~
1 | 1
A Total ammonia, as N ~
nrj/\ Total load= 900 kg
n 1 1 H n \
1 1 H \'\ f] \^
- --HiHrlTi f! I"""""-- — »-j_ 1 i ~
, ,
~ n fill
InJlJi
A Total nitrogen, as N
/ \ Total load = 13, 000 kg
in V ~
IB n>^ , -
p.
— |
1 . 1 |
[|\I Total phosphorus, as P ~
;| 1 Total load =2900 kg ~
IJ '< ^v^
1 II ': ^X
' | ' 1 !" 1
j. Total lead ~
|\ Total load = 2200 kg
_jj| V^^ , :
2500
0 ^
100 ^
O
o
UJ
CO
cc
LJ
a.
0 to
500 *s
oc.
' -z
,uT
J. 1
o 5
100 2
t-
z
CO
40
-------
and Tanyard Branch, tributaries to Peachtree Creek upstream of the samplxng
site were not included in the sum (except as part of the load calculated for
the Peachtree Creek site). Nancy Creek was included because it is downstream
of the Peachtree Creek sampling site.
Because the residual loads are calculated by mass balance rather than
from measured values, they need to be evaluated to determine if they are
realistic. An evaluation was done by determining the average residual con-
centrations (residual loads divided by residual volume) of the constituents
in Tables 14 and 15 and comparing them to the mean wet-weather concentrations
of similar constituents for streams in the study area. Residual mean consti
tuent concentrations we,re 0.52 mg/L total nitrogen, 0.25 rtg/L total phospho-
rus, and 2.2 mg/L total organic carbon for the November storm and 1.7 mg/L
total nitrogen, 0.28 mg/L total phosphorus, and 6.9 mg/L total organic carbon
for the October storm. The concentrations appear to be realistic. In gene-
ral, they were 2 to 3, times lower than the mean wet-weather concentration of
similar-constituents for the Peachtree Creek site.
The data in Table 14 indicate that for the November storm, point-source
total nitrogen and total phosphorus loads were significantly greater than the
nonpoint-source loads. The point-source total organic carbon load was less
than the nonpoint-source load. At the Fairburn site, point discharges con-
tributed only about 8.-7 percent of the total discharge volume, but 72 percent
of the total nitrogen load, 67 percent of the total phosphorus, and 40 per-
cent of the total organic carbon. Nonpoint discharges contributed roughly yi
percent of the total discharge at the Fairburn site, but only 28 percent of
the total nitrogen load, 33 percent of the total phosphorus, and 60 percent
of- the'total organic carbon. The combined percentage contribution of loads
at the Fairburn site from the measured CSO's was 0.9 percent for total nitro-
gen, 1.1 percent for total phosphorus, and 2.3 percent for total organic car-
bon. The approximate percentage contribution of loads at the Fairburn site
from the Peachtree Creek basin (Peachtree Creek at Atlanta, plus Nancy Creek
at Randall Mill Road) was 5.9 percent for total nitrogen, 5.0 percent for
total phosphorus, and 17 percent for total organic carbon.'
The data in Table 15 indicate that for the October storm, nonpoint-
source loads were greater than point-source loads. Point-source loads, how-
ever, were high. Nonpoint discharges contributed roughly 96 percent of the
total discharge at the Fairburn site, 68 percent of the total nitrogen load,
61 percent of the total phosphorus load, and 88 percent of the total organic
carbon load. Point discharges contributed about 4 percent of the discharge
volume, 32 percent of the total nitrogen, 39 percent of the total phosphorus,
and 12 percent of the total organic carbon loads. For this storm period, the
Peachtree Creek at Atlanta site was the only tributary sampled in the Peach-
tree Creek basin. The percentage contributions of total nitrogen, total
phosphorus, and total organic.carbon loads from Peachtree Creek (at Atlanta
site) to the Chattahoochee River near Fairburn site were 17, 19, and 1J per-
cent, respectively.
Impact of Stormwater Runoff on Dissolved-Oxygen Concentration
The impact of flow regulation and stormwater runoff on the DO and
dissolved-solids concentrations in the Chattahoochee River is detected by an
41
-------
TABLE 14.—COMPUTED CONSTITUENT LOADS AND PERCENTAGES OF LOADS CONTRIBUTED BY
TO THE CHATTAHOOCHEE RIVER FOR A STORM ON NOVEMBER 27-29, 1976
[CSO, Combined sewer,overflow]
TRIBUTARIES
Sampling site
at Atlanta, Ga.
(02336000)
Piedmont Park CSO,
at Atlanta, Ga.
(02336274)
26th Street Extn.
CSO, at Atlanta, Ga.
(02336290)
at Atlanta, Ga.
(02336300)
Randall Mill Rd.,
at Atlanta, Ga.
(02336380)
constituent sources
in the Atlanta-
Fairburn reach
Measured point
sources, total
of 7 sites
near Fairburn, Ga.
(02337170)
Drainag
area
(Km2)
3,760
9.6
9.1
225
90.1
1,360
-
5,340
Discharg
volume
during
storm
(L)
68xl08
1.2xl08
1.2xl08
29xl08
3.1xl08
147xl08
23xl08
270x10 8
Percent
of
discharg
at
Fairburn
25
0.4
0.4
' 11
1.1
54
8.7
100
Total
nitroge
load
(Kg)
4,900
180
340
3,000
370
7,700
1,000
7,000
Percent
of
nitrogen
load at
Fairburn
8.6
0.3
0.6
5.3
0.6
14
72
00
Total
phos-
phoru
load
(Kg)
600
100
52
640
99
3,700
0,000
5,000'
Percent
of
phos-
phorus
load a
Fairburn
4.0
0.7
0.4
4.3
0.7
25
67
00
Total
organi
carbon
load
(Kg)
37,000
: 2,700
940
24,000
3,100
32,000
64,000
60,000
Percent,
jof
organic
carbon
load at
23
f
'1.7
',0.6
f
15
t
[1.9
I
20
40
00
TABLE 15.—COMPUTED CONSTITUENT LOADS AND PERCENTAGES OF LOADS CONTRIBUTED BY
TO THE CHATTAHOOCHEE RITOR FOR A STORM ON OCTOBER 8-9, 1977
TRIBUTARIES
Sampling site
Chattahoochee River
at Atlanta, Ga.
(02336000)
at Atlanta, Ga.
(02336300)
Unmeasured flow and
constituent sources
in the Atlanta-
Fairburn reach
Measured point
sources, total of
7 sites
Chattahoochee River
near Fairburn, Ga.
(02337170)
Drainage
area
(Km2)
3,760
225
1,360
-
5,340
Discharge
volum'e
during
storm
(L)
180xl08
56xl08
130xl08
14xlQ8
380x10 8
Percent
of
discharge
at
Fairburn
47
15
34
4
100
Total
nitrogen
load
(Kg)
17,000
13,000
22,000
,25,000
77,000
Percent
of
nitrogen
load at
Fairburn
22
17
29
32
100
Total
phos-
phorus
load
(Kg)
3,000
3,100
3,600
6,300
16,000
Percent
of
phos-
phorus
load at
Fairburn
19
19
23
39
100
Total
organic
carbon
load
(Kg)
150,000
41,000
90,000
39,000
320,000
Percent
if '
organic
carbon
load at
47
13 '*
28
12
[100
42
-------
automatic water-quality monitor located at the Fairburn site. (See Figure 1.)
Near this site the DO concentration reaches a point of minimum DO produced by
oxygen-consuming constituent loads to the river. Figure 7 shows that during
low flow (about 3.4 x lO^L/s (1,200 ft3/s) at Atlanta), minimum DO occurs
about 18 km (11 mi) downstream of the Fairburn site and is only slightly less
that at Fairburn. At higher flows the minimum DO concentration is displaced
downstream. At a streamflow of, about 5.1 x 10^L/s (1,800 ft^/s) the minimum
DO occurs about 43 km (27 mi) downstream of the Fairburn site (10).
The flow pattern and DO concentrations that occur at the Chattahoochee
River near Fairburn site as a result of flow regulation by iBuford Dam and
stormwater runoff are shown in Figure 8. Daily rainfall measured at one .site
in the Peachtree Creek basin and mean daily discharge.at the Peachtree Creek
at Atlanta site are included in the illustration. The 6-month time period
includes mainly the summer and fall seasons.. The shaded columns which extend
over 2-day periods indicate the days when river flows at the Fairburn_site
were not influenced by water released by Buford Dam for power generation. .
Typically, these times of low flow occurred at the Fairburn site every Sunday
and Monday from Jutie through September. After September, the storms rather
than flow regulation were primarily responsible for the variations in dis-
charge and DO at the Fairburn site. The lowest daily minimum DO concentra-
tions during June through September were concurrent with the Sunday and Mon-
day daily mean low flows. At higher flows produced by water released_during
the! other days of the week by Buford Dam, daily minimum DO concentrations
were much higher. ,
The impact of stormwater runoff on DO concentrations appears to be most
severe during the summer at times when the river is at low flow. However,
data are scarce because the occurrence of stormwater runoff at times of low
flow in the river is infrequent. For example, Figure 8 shows that during the
summer of 1977 stormwater runoff occurred at low flow only once (July 26;
In the fall, stormwater runoff occurred when the river was at low flow only
on September 26 and October 1, 8, and 25. On September 26 and October 1 the
DO concentration reached a minimum of 3.8 mg/L, which was about 1 mg/L lower
than occurred' during dry-weather low flow the first 3 weeks in September.
Runoff produced by heavy thunderstorms on October 8 and 25 caused some
decrease in the minimum DO at the Fairburn site, but the change was not as
marked as that during the July 26 summer storm or the September 26 and Octo-
ber 1 fall storms.
The hourly variations of discharge, DO, and specific conductance that .
occurred at the Fairburn site during the July 26 and October 8, 1977 and_
November 27, 1976 storms are shown in Figures 9, 10, and 11. The specific
conductance and discharge at the Fairburn site were similar prior to eac£
storm which indicates the presence of similar dissolved-solids loads. River
temperature was highest during the July storm and was a_major factor causing
the lowest prestorm DO concentrations at the Fairburn site.
The effect of runoff from each storm was an increase in specific conduc-
tance' and a decrease in DO as the pollutant load passed the Fairburn .site.
An improvement in river quality followed when the hydropulse water (released
water from Buford Dam) passed the monitor site. Figure 9^shows that the
43
-------
0)
O
O
O
I o
c
:~ o»
w.E
C l-
O 3
— T3
O >-
^ to
'
.
go:
o
u
0)
x
o
I
T3
0)
O
cn
M
0)
3'
o>
swvdsniiw NI'NHOAXO aaAiossm
44
-------
6O
40
_
_JUJ
?l 20
0
60
Peachtree Creek basin
o 50-
x
40
8 30
o:
UJ
20
10
LLJ 0
3 400;
A
A
Peachfree Creek at
Atlanta, Ga.
g 300
a: •
s
o
<2 200
a.!
100
<
UJ
Chattahoochee River near
Fairburn, Ga.
\
~2 9
O ^- n"
^"JU 8
"•See 6
4
-------
o
-------
25
&•
z
s 0
400
Average of rainfall from two sites-
in Peachtree Creek basin
Specific conductance
Dissolved-oxyg«n
concentration
XPLANATION
A—Flow and quality at initieil
storm runoff
3—Flow and quality during rapid
increase in discharge from
storm runoff
—Flow and quality during
recession in discharge .
—i 40
20
LL)
LU
00
O
80
6O
uT
O
O
4O
O
O
LU
a.
en
20
1200 OOOO
TIME, IN HOURS
9
OCTOBER 1977
Figure 10.— Impact of stormwater runoff on specific conductance and
dissolved-oxygen concentration at Chattahoochee River
near Fairburn, October 8—10, 1977.
47
-------
ffi
T
Average of rainfall from two
sites in Peachtree Creek basin
170
I6C
10
O 140
a
O 120
rr
£ 100
CO
rr
UJ
t 80
O
rr
60
o
to
^ 40
20
v
Discharge
Dissolved-oxygen
concentration
o
oooo
H—
'Specific conductance
EXPLANATION
A—Flow and quality at initial
storm runoff
B—Flow and quality during
rapid increase in discharge
from storm runoff
C—Flow Ond quality during
rapid increase in discharge
from hydropulse
1200
25
0000 1200
TIME, IN HOURS
26
JULY 1977
12
—1!20
rr
UJ
rr
: CO
s.H -I
rr
UJ
LU
CD
Q
UJ
O
to
to
0000
1200
100
80
27
t
Figure II.— Impact of stormwater runoff and hydropulse water on
specific conductance and dissolved-oxygen concentration
at Chattahoochee River near Fairburn, July 25-27, 19,77.
UJ
o
rr
UJ
°-
to
rr
a
60
uj
o
z
40 O
O
O
0
O
, t
O
UJ
Q.
to
48
-------
pollutant load from the November storm resulted in an Initial increase in
specific conductance, and about a 1-mg/L decrease in DO as the initial runoff
passed the Fairburn site (section A). After the initial runoff, river qual-
ity improved somewhat, as indicated by a general decrease in specific conduc-
tance and an increase in DO (section B). Once the hydropulse reached Fair-
burn, the river quality showed further improvement (section C).
Figure 10 shows that the constituent load from the October 8-10, 1977,
storm resulted in an initial increase in specific conductance and about a
1-mg/L decrease in DO as the initial runoff passed the monitor site (section
A). After the initial runoff, river quality improved, as indicated by a gen-
eral decrease in specific conductance and an increase in DO (section B). A
hydropulse did not occur during the storm-runoff period, but river quality
continued to improve during the recession in discharge (section C).
The most substantial changes in quality conditions occurred during the
July storm. Figure 11, section A, indicates that the prestorm stream condi-
tions at the Fairburn site were relatively stable. As the pollutant load
from Peachtree Creek and other basins passed the Fairburn site, the DO de-
clined about 4 mg/L to a minimum of about 1.6 mg/L (section B). Correspon-
dingly, the specific conductance increased about 30 umhos/cm to a maximum of
114 umhos/cm. In section C the effects of the hydropulse water become
apparent, as indicated by a marked increase in DO and a decrease in specific
conductance.
'. At the Fairburn site on the Chattahoochee River, the major effect of
pollutant loads from stormwater runoff occurred on the rising limb of the
discharge hydrograph, as indicated by a maximum specific conductance and a
minimum dissolved-oxygen concentration at this time. River quality improved
during the period of discharge recession after peak flow or when hydropulse
water reached the Fairburn site.
Data indicate that.runoff from thunderstorms that occur in the summer
has a much greater impact on dissolved oxygen and specific conductance than
runoff from storms in the fall or winter season. Summer storms could produce
severe quality conditions in the Chattahoochee River downstream of Atlanta,
if the river is at low flow. However, summer regulation of the river norm-
ally provides low flows only on weekends. Thus, only about 1.5 days out of
7, or 21 percent of the time, is the Chattahoochee River at a flow that could
result in severe degradation of stream quality from stormwater runoff.
49
-------
REFERENCES
1.
2.
3.
4.
8.
10.
American Public Health Association, American Water Works Association
and Water Pollution Control Federation, 1975, Standard Methods for
the examination of water and wastewater: (14th ed.),.American Pub-
lic Health Association, Washington, D. C., 1193 p. ,
• . . i
Black, Crow, and Eidsness, Inc., April 1974, Three river water quality
management plan: A report to the city of Atlanta, 360 p. J
Cherry, R. N., Faye, R. E., Stamer, J. K., and Kleckner, R. L.J1978,
Summary report of the intensive river-quality assessment, upper
Chattahoochee River basin: U.S. Geological Survey Circulat
[in press]. ;
Fay, R. E., Carey, W. P., Stamer, J. K., and Kleckner, R. L., 1978,
Erosion, sediment discharge, and channel morphology in the!upper
Chattahoochee River Basin, Georgia: U.S. Geological Survey, Open-
File Report 78-576, 133 p. , i
Federal water pollution control act amendments of 1972, Public Law 92-
500, 92d Congress, S. 2770, October 18, 1972, 89 p. i
Georgia Department of Natural Resources, Environmental Protection Divi-
sion, June 28, 1977, Water-use classifications (including trout
stream designations) and water quality standards for the surface
waters of the State of Georgia, 22 p. i
!
Greeson, P. E., Ehlke, T. A., Irwin, G. A., Lium, B. W., and Slack,
K. V., 1977, Methods for collection and analysis of aquatic! bio-
logical and microbiological samples: U.S. Geological Survey Tech-
niques of Water-Resources Investigations, Book 5, Chapter A4,
332 p. I
Holbrook, R. F., Perez, A. I., Turner, B. G., and Miller, H. I.,I Decem-
ber 1976, Stormwater studies and alternatives in Atlanta: [Journal
of Environmental Engineering Division, p. 1261-1277. ,
Skougstad, M. W., 1978, Methods for the analysis of inorganic substances
in water and fluvial sediments: U.S. Geological Survey Techniques
of Water-Resources Investigations, Book 5, Chapter Al, p. 916-921.
Stamer, J. K., Cherry, R. N.,, Faye, R. E., and Klechner, R. L., 1978
Magnitudes, nature, and effects of point and nonpoint discharges in
the Chattahoochee River basin, Atlanta to West Point Dam, Georgia:
U.S. Geological Survey Open-File Report 78-577, 105 p. \
50
-------
REFERENCES (continued)
11 U.S. Environmental Protection Agency, April 1977, Sampling and analysis
! procedures for screening of industrial effluents for priority pol-
lutants: Environmental Monitoring and Support Laboratory, Cincin-
nati,, Ohio, 69 p.
12. U.S. Environmental Protection Agency, July 1976, Quality criteria for
water: Washington, D. C., 256 p.
12 1971 water Quality Office, Storm and combined sewer pollution
sources and abatement, Atlanta, Georgia: Black, Crow and Eidsness,
Inc., U.S. Environmental Protection Agency Report No. 11024 ELB,
173 p.
51
-------
TECHNICAL REPORT DATA
(flease read Instructions on the reverse before completing)
EPA-600/2-80-094
IMPACT OF URBAN STORM RUNOFF ON STREAM QUALITY
NEAR ATLANTA, GEORGIA
James B. McConnell
9. PERHOHMIi\lt),OHBANIZATION NAME AND ADDRESS
U.S. Geological Survey
Water Resources Division
Suite B, 6481 Peachtree Industrial Boulevard
Doraville, Georgia 30360
12. SPONSORING AGENCY NAME AND ADDRESS
Municipal Environmental Research Laboratory cin. OH
Office of Research and Development ''
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
3. RECIPIENT'S ACCESSION NO.
5. REPORT DATE ;
August 1980 (Issuing Date)
6. PERFORMING ORGANIZATION CODE
8. PERFORMING ORGANIZATION REPORT NO.
10. PROGRAM ELEMENT.NO.
35B1C,AP#C611A,SOS#1,TASK 62
11-IAG NO.
EPA-IAG-D6-0137
13. TYPE OF REPORT AND PERIOD COVERED
Final 10/75 to 10/77
14. SPONSORING AGENCY CODE
EPA/600/14
Project Officer: John N. English (513) 684-7613
The objective of this study was to assess the impact of stormwater runoff from
point and nonpoint sources on the water quality of receiving streams in the Atlanta
area. Emphasis was placed on the collection of water-quality data in the summer and
the^ry-we ^5ermine the imPact °n streams from runoff produced by thunderstorms during
Compared to dry-weather flow, stormwater rnnnff ^•o.-n-if-r^or^i^ ,-„ j ^.
age concentration of suspended sediment, BOD5, total organic carbon, total ammonia"'"
!1\' !£ APJOSPhorus> fecal collform bacteria, and trace metals in most receiving
tration of the.AtlanJf Metropolitan Area. Stormwater runoff increased the! mean concen-
^n"°L°f m°St conf ltuents 2- to 5-fold. In most streams, the dissolvedfoxygen con-
centrations generally increased to near saturation during periods of stormwate? runoJf
» n«.J,S djs^olv^-°xygen concentration in the Chattahoochee River near -Fairburn during
a period of low flow reached a low of 1.5 milligrams per liter (a 4-milligram per lite?
decrease) as a result of runoff from a July thunderstorm. However, low f!S dSing the
summer and autumn occurs only about 21 percent of the time due to flow regulation of
o^c!iVSr% Tll*flushing and dilution effect of water released for power generation
caused a significant improvement in Chattahoochee River quality most of the time!
17.
DESCRIPTORS
KEY WORDS AND DOCUMENT ANALYSIS
*Dissolved oxygen
Surface-water runoff
Combined sewers
Water pollution
Nutrients
*Water quality
Pesticides
18. DISTRIBUTION STATEMENT
Release to public
EPA Form 2220-1 (Rev. 4-77)
b.lDENTIFIERS/OPEN ENDED TERMS
Rainfall
Urban runoff
Trace organics
Trihalomethanes
19. SECURITY CLASS (ThisReport/
Unclassified
20. SECURITY CtASS (Thispage)
Unclassified
COSATI Field/Group
13 B
21. NO. OF PAGES
64'
52
U.S. GOVERNMENT PRINTING OFFICE-: 1980--657-165/0129
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