EPA/600/A-92/171
FIFTH INTERNATIONAL CONFERENCE ON URBAN STORM DRAINAGE
U.S. EPA's MANUAL OF PRACTICE FOR THE INVESTIGATION AND CONTROL OF
CROSS-CONNECTION POLLUTION INTO STORM DRAINAGE SYSTEMS
Robert E. Pitt. Dept. of Civil Engineering, Univ. of Alabama at Birmingham, AL 35294
Richard Field, Chief, Storm and Combined Sewer Program, U.S. EPA, Edison, NJ 08837
ABSTRACT: Dry-weather flows discharging from storm drainage systems can contribute
significant pollutant loadings to receiving waters. If these loadings are ignored, little
improvement in receiving water conditions may occur with many stormwater control
programs. This paper summarizes the first phase of an EPA sponsored research project
to develop a manual to investigate these connections.
KEY WORDS: Cross-connections: Stormwater; Dry-weather Flow; Manual of Practice
1. INTRODUCTION
This paper is a summary of the first phase of a current EPA research project to develop
investigative techniques>to assist local governments in identifying the magnitude and
sources of cross-connections in their storm drainage systems	
Discharges from storm drainage outfalls can be a combination of dry-weather base
flows; stormwater runoff; snowmelt water; intermittent discharges of debris, wash-
waters, and other waste materials into storm drains; and the relatively continuous
discharges of sanitary and industrial cross-connected wastewaters, these discharges
include stormwater that contains the washoff of pollutants from all land surfaces during
rains, including washoff of pollutants from areas such as industrial material and waste
storage areas, gas station service areas, parking lots, and other industrial and
commercial areas, etc. Therefore, the quality of urban runoff can vary greatly with time
(dry versus wet-weather, cold versus warm weather, etc.) and location.
The discharge of sanitary and industrial wastes into storm drainage (cross-connections)
can lead to serious water pollution problems. In many cases, storm drain discharges are
badly polluted by stormwater alone, without the additional pollutant loadings associated
with sanitary or industrial connections. The addition of sanitary wastes increases the
concentrations of organic solids and nutrients, and increases the potential of pathogenic
microorganisms in the runoff. Industrial wastewaters can be highly variable, but usually
increase the concentrations of many filterable heavy metals in runoff. In many cases,
annual discharge loadings from stormwater outfalls can be greatly affected by dry-
weather discharges (Pitt and Shawley 1982; Pitt 1984; and Pitt and McLean 1986, as
examples).
Dry-weather and wet-weather urban runoff flows have been monitored during many
urban runoff studies that have found that discharges observed at outfalls during dry
weather were significantly different from wet-weather runoff. Warm and cold weather
runoff was also contrasted during some studies and was also found to be quite different.
During the Castro Valley, California, Nationwide Urban Runoff Program (NURP) study,
Pitt and Shawley (1982) found that the dry-weather flows were very hard and had very
few nonfilterable pollutants, while the stormwater runoff was quite soft and had
substantial nonfilterable metals. The dry-weather flows were found to contribute
substantial quantities of many pollutants, even though the concentrations were not high.
The long duration of baseflows in many areas of North America (about 95 percent of the
time) off-set their lower concentrations and lower flow rates as compared to wet-weather
(stormwater) flows.
The Bellevue, Washington, NURP project (Pitt and Bissonnette 1984) summarized the
reported incidents of intermittent discharges and dumpings of pollutants into the local
storm drainage system. During a three year period of time, about 50 citizen contacts
were made to the Bellevue Storm and Surface Water Utility District concerning water

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quality problems. About 25 percent of the complaints concerned oil being discharged
into catchbasins. Various industrial and commercial discharges into the storm drainage
system were detected. Concrete wastes flushed from concrete trucks at urban job sites
were a frequently occurring problem. Cleaning establishment discharges into creeks
were also a common problem. Several vehicle accidents also resulted in spillage of
gasoline, diesel fuel, hydraulic fluids, and lawn care chemicals from damaged trucks that
flowed into the storm drain inlets. Pitt (1984) also monitored both dry- ana wet-weather
discharges from stormwater outfalls in Bellevue and found significant pollutant yield
contributions associated with dry-weather discharges from residential areas.
Dry-weather flows in a monitored Toronto residential area were found to have high
pesticide concentrations, while a monitored industrial area had dry-weather flows that
had high concentrations of organic and metallic toxicants (Pitt and McLean 1986). More
than 50 percent of the annual discharges of water volume, total residue, chlorides, and
bacteria, from the monitored industrial, residential, and commercial areas, were
associated with dry-weather discharges. Substantial metal discharges, especially from
the industrial area, were also found to be associated with dry weather.
Gartner Lee and Associates, Ltd. (GLA 1983) conducted an extensive survey of dry-
weather storm drainage in the Humber River watershed (Toronto) in an attempt to
identify the most significant urban runoff pollutant sources. About 625 outfalls were
sampled two times during dry-weather, with analyses conducted for many pollutants,
including organics, solids, nutrients, metals, phenols, and bacteria. About 1/3 of the
outfalls were discharging at rates greater than 1 L/sec. The dry-weather flows were
found to contribute significant loadings of nutrients, phenols, and metals, compared to
upstream conditions. Further investigations identified many industrial and sanitary
sewage cross-connections into the storm drainage system. An apartment building with
the sanitary drains from eight units illegally connected to the storm drainage system was
typical of the problems found. Other problems were found in industrial areas, including
fluid dripping from animal hides in tannery storage areas, and yard washdown runoff
from meat packing plants.
2. METHODOLOGY
A specific objective of this project is to identify the most promising techniques to identify,
quantify, and locate cross-connections of sanitary and industrial wastes entering storm
drainage systems.
As noted above, cross-connections can take multiple forms. Many cross-connection
problems are associated with intermittent discharges. These intermittent discharges
occur during wet weather as runoff from storage areas, or as illegal dumping or washing
operations tnat occur during dry or wet weather. Other cross-connection problems are
caused by continuous connections that can occur during both wet and dry weather.
These can be associated with "non-contact" cooling water discharges (which frequently
contain a variety of chemicals, including algicides and corrosion inhibitors), other
industrial wastewater connections, and sanitary sewage waste connections, for example.
This project is examining procedures that can be used to identify the significance and
type of either intermittent or continuous discharges occurring during dry weather. The
pollutant contributions associated with cross-connections can be distinguished by
unique characteristics based on water types and typical pollutants. Knowing the specific
water source for each flow component could enable the relative mixture of
uncontaminated baseflow and the wastewater cross-connections to be calculated.
The following list summarizes the potential contaminated residential area cross-
connection sources being investigated:
Sewage sources:
o raw sewage from directly connected or leaky sanitary
sewerage
o septage from improperly operating septic tank
systems
Household automobile maintenance:
o car washing runoff
o radiator flushing
o engine de-greasing
o improper oil disposal

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Residential irrigation sources:
o over-watering runoff
o direct spraying of impervious surfaces
Roadway and other accidents:
o fuel spills
o spills of truck contents
o pipeline spills
Other:
o washing of ready-mix trucks
o laundry wastes
o improper disposal of other household toxic
substances
o dewatering of construction sites
o sump pump discharges
o contaminated surface and groundwaters
Commercial and industrial dry-weather discharges are being considered in a separate
study conducted by Triad Engineering of Milwaukee, Wisconsin. The results of the Triad
study are being incorporated into the complete EPA manual. The commercial and
industrial approach is stressing differentiating industrial categories used in the industrial
discharge permit program.
The natural baseflow raw water source flows, along with the sewage related sources and
many industrial sources, would be relatively continuous in flow duration. The other
sources would be intermittent. As a drainage area increases in size, however, the
probability also increases that dry-weather discharges associated with individual
intermittent activities would appear continuous at the outfall. Most of the studies
referenced previously found flows at the monitored outfalls much of the time during dry
weather, even though the flows were normally very low. The quality of the flows also
changed dramatically at different times of the day and year for the monitored Toronto
industrial outfall (Pitt and McLean 1986).
This study is identifying unique physical, biological, or chemical characteristics that
would distinguish these different flow components.
The purpose of the monitoring procedures is to separate the outfalls into three general
categories (with a known level of confidence) to identify which outfalls need further
analyses and investigations. These categories are: (1) pathogenic or toxic pollutant
sources, (2) nuisance and aquatic life threatening pollutant sources, and (3) unpolluted
water sources. The pathogenic and toxic pollutant source category would be considered
the most severe ana could cause disease upon water contact or consumption and
significant impacts on receiving water organisms. They may also cause significant water
treatment problems for downstream consumers, especially for soluble metal and organic
toxicants. These pollutants may originate from sanitary, commercial, and industrial
wastewater cross-connections. Other residential area sources (besides sanitary
wastewater), such as inappropriate household toxicant disposal, automobile engine de-
greasing, vehicle accident clean-up, and irrigation runoff from landscaped areas
excessively treated with chemicals (fertilizers and pesticides) may also be considered in
this most critical category.
Nuisance and aquatic life threatening pollutant sources can originate from residential
areas and may include laundry wastes, landscaping irrigation runoff, automobile
washing, construction site dewatering, and washing of ready-mix trucks. These
pollutants can cause excessive algal growths, tastes and odors in downstream water
supplies, and highly colored, turbid or odorous waters.
Clean water discharged through stormwater outfalls can originate from natural springs
feeding urban creeks that have been converted to storm drains, infiltrating groundwater,
infiltrating domestic water from water line leaks, etc.
The proposed monitoring approach is separated into three phases:
o initial mapping effort
o initial field surveys
o confirmatory chemical analyses.

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These three phases will be followed by detailed storm drainage and site investigations to
identify specific pollutant contributors and control options.
An important requirement of the methodology is that an initial field screening effort would
require minimal effort and would have little cnance of missing a seriously contaminated
outfall. This screening program would then be followed by a more in-depth analysis to
more accurately determine the significance and source of the dry-weather pollutant
discharges.
The most important step in a cross-connection investigation is in preparing and studying
drainage and land use maps. The most important objective of the mapping activities
would be to identify the locations of all of the stormwater outfalls. Finding the outfalls is
not trivial. In the case studies examined, repeated trips typically uncovered additional
outfalls that could not be located during earlier excursions. It is very difficult for
communities to maintain up-to-date mapping of drainage facilities.
Another important objective of the initial mapping activities is to outline the drainage
areas discharging to the outfalls. These drainage maps should identify the
predevelopment streams that may have been converted to storm drains (indicating the
likelihood of natural uncontaminated baseflows) and the current and past land uses.
Specific land use categories to be indicated should include commercial and industrial
land uses, plus other activities that may contribute runoff problems (such as land fills).
Any industrial activities having significant potential of contributing flows to the storm
drainage system, as indicated by Triad's analyses, need to be specifically identified and
located.
Further drainage area investigations would be conducted after the outfall studies have
indicated dry-weather discharge problems. These would include drainage system and
industrial and commercial site studies (such as dye and smoke studies) to locate
specific cross-connections.
The initial field surveys would include physical and limited chemical evaluations of outfall
conditions and would be conducted to minimize "false negatives" (outfalls actually having
important discharges, but falsely classified as not needing further investigation), various
physical characteristics near the outfall can provide evidence that inappropriate
discharges periodically occur. However, repeated trips to the outfalls significantly
increase the probability of identifying problem outfalls.
It is difficult to develop a procedure that will separate the outfalls into clear "problem" and
"no problem" categories. In some of the case studies investigated, only correcting
problems at the most critical outfalls resulted in insufficient receiving water quality
improvements. It may be important to eventually correct all cross-connection problems
throughout a city, not just the most severe problems.
Many different analytical methods are being evaluated as part of this project. The initial
screening effort should include the following:
o placement of outfall identification number;
o outfall discharge flow estimate;
o floatables, color, oil sheen, and odor
characteristics of water;
o other outfall area characteristics, such as
stains, debris, damage to concrete, corrosion, unusual
plant growth, or absence of plants;
o water temperature
o specific conductance;
o potassium concentration;
o ammonia concentration;
o fluoride concentration; and
o surfactant concentration.
These characteristics can be relatively easy to obtain at the outfall location, depending
on the needed detection limits for the chemical analyses and potential interferences.
Simple outfall estimates of discharge, and noting the presence of oil sheens, floatables,
color, odors, etc. will probably be the most useful indicators of outfall problems. These
observations will need to be repeated several times, especially if non-continuous

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discharges are likely. The presence of stains and structural damage will greatly assist in
identifying significant non-continuous discharges.
Notably absent from the above list are pH and dissolved oxygen. These have been
included in several previous cross-connection studies, but with limited value. However, in
areas having known industrial sources, pH may be an important parameter that would
have to be added to this list.
Specific conductance and temperature can be quickly and easily measured using a dual
dedicated meter. Water color can be quantified using a comparative colorimetric meter
or spectrophotometer in the field.
Fluorides can be detected using a variety of methods in the field, including field
colorimetric kits having detection limits of less than 0.15 mg/L. This detection limit may
not be sufficient to detect low levels of dilution with adequate precision. Dedicated
specific ion meters for fluorides are available having very low detection limits (2 ug/L)
that would be quite capable of detecting very smalfdilutions.
Detergents (or surfactants) can be detected in the field using a comparative colorimetric
method (having a detection limit of 50 ug/L) or with a recently developed auto titration
method in the laboratory having very few interferences and much lower detection limits.
Other ions, such as potassium and some nutrients (such as ammonia nitrogen), have
been used to successfully identity sanitary sewage influence in base flows. Toxicity
screening tests would be useful in areas known to have commercial or industrial
activities. Some individual metals (especially copper and chromium) could also be used
in areas having these land uses. In most cases, it will probably be necessary to conduct
a variety of carefully selected tests because of the large number of potential pollutant
sources that probably occur in most drainage areas.
This scheme should allow an efficient determination of the general category
(toxic/pathogenic, nuisance, or clean) of the water being discharged. In many cases,
fluorides can be used to separate untreated water from treated water sources. Untreated
water sources may include discharges from natural waters or untreated industrial waters.
If the treated water has no fluoride added, or if the natural water has fluoride
concentrations close to treated water fluoride concentrations, then fluoride may not be
an appropriate indicator. Specific conductance may also serve as a rough indicator of
major water source.
Water from treated water supplies (that test positive for fluorides, or other suitable tracer)
can be relatively uncontaminated (domestic water line leakage or irrigation runoff), or it
may be heavily contaminated. Surfactants may be useful in determining the presence of
sanitary wastewaters. Surfactants in water from treated water sources could indicate
sanitary wastewaters, laundry wastes, car washing water, or other waters having
detergents. If the surfactants were not present, then the treated water could be relatively
uncontaminated (such as from domestic water line leaks or irrigation runoff), or it may be
from rinsing ready-mix trucks or other rinsing activities (such as accident scenes).
Sanitary wastewater would have the most consistent characteristics (volume ana
characteristic) compared to most of the other potential sources. Obviously, odor and
other physical appearances (such as turbidity, foaming, color, and temperature) would
be very useful in identifying sanitary wastewater.
In order to identify the specific contaminant sources in the drainage system, further
detailed analyses are needed. These may include drainage system surveys (tests for
specific pollutants, visual inspections, and smoke and dye tests), in-depth watershed
evaluation (including aerial photographs), and industrial and commercial site studies.
3. CONCLUSIONS
Many urban runoff projects have found that dry-weather discharges from stormwater
outfalls can contribute significant pollutant loadings. Ignoring these loadings can lead to
improper conclusions concerning stormwater control requirements.
Municipalities that have recognized the importance of dry-weather flows have
investigated their sources using various methods. Unfortunately, most municipalities
have very large numbers of outfalls and an efficient method is needed to separate the
outfalls creating the most severe problems. The most important category is for outfalls
contributing pathogens or toxicants. These are most likely originating from sanitary

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wastewater or industrial cross-connections. An initial screening analysis at all outfalls
should have a high probability of identifying all outfalls in this category. Future project
phases will evaluate these outfall procedures in test conditions. Procedures to identify
and correct specific cross-connections will also be summarized in these future project
phases.
REFERENCES
Eganhouse, R.P., D.P. Olaguer, B.R. Gould and C.S. Phinney. "Use of Molecular Markers
for the Detection of Municipal Sewage Sludge at Sea." Marine Environmental Research.
Volume 25, No.1. pp. 1-22. 1988.
GLA (Gartner Lee and Associates, Ltd.). Toronto Area Watershed Management Strategy
Study, Technical Report #1, Humber River and Tributary Dry-weather Outfall Study.
Ontario Ministry of the Environment. Toronto, Ontario, November 1983.
Hargesheimer, E.E. "Identifying Water Main Leaks with Trihalomethane Tracers." Journal
American Waterworks Association, pp. 71-75. November 1985.
Pitt, R. Characterization, Sources, and Control of Urban Runoff by Street and Sewerage
Cleaning. Contract No. R-80597012, U.S. Environmental Protection Agency, Office of
Research and Development, Cincinnati, Ohio, 1984.
Pitt, R. and P. Bissonnette. Bellevue Urban Runoff Program, Summary Report. U.S.
Environmental Protection Agency and the Storm and Surface Water Utility, Bellevue,
Washington, November 1984.
Pitt, R. and J. McLean. Humber River Pilot Watershed Project, prepared for the Ontario
Ministry of the Environment, 1986.
Pitt, R. and G. Shawley. A Demonstration of Nonpoint Pollution Management on Castro
Valley Creek. Alameda County Flood Control District (Hayward, California) and the U.S.
Environmental Protection Agency, Washington, D. C., June 1982.

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TECHNICAL REPORT DATA
(Plccse read Instructions on the reverse before com
1. REPORT NO.
FPA/finn/A-q?/i7i
4. TITLE AND SUBTITLE
U.S. EPA's Manual of Practice for the Investigation and
Control of Cross-Connection Pollution into Storm Drain-
age Systems	
5. REPORT DATE
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
1	2
Richard Field and R. Pitt
8. PERFORMING ORGANIZATION REPORT NO.
9.PERFORMING ORGANIZATION NAME AND ADDRESS
USEPA/SCSP/WHWTRD
Edison, NJ 08837
^ept of Civil Engineering
University of Alabama—Birmingham. AL 35294
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
68-C9-0033
12. SPONSORING AGENCY NAME AND ADDRESS
Risk Reduction Engineering Laboratory—Cincinnati, OH
Office of Reserach and Development
US Environmental Protection Agency
Cincinnati, OH 45268
13. TYPE OF REPORT AND PERIOD COVERED
published paper	
14. SPONSORING AGENCY CODE
EPA/600/14
15. supplementary NOTES project Officer = Richard Field	, (COMM)321-6674
Proceedings of the Fifth International Conference on Urban Storm Drainage
16. ABSTRACT
-Dry-weather flows discharging from storm drainage systems can contribute significant
pollutant loadings to receiving waters. If these loadings are ignored, little
improvement in receiving water conditions may occur with many stormwater control
programs. This paper summarizes the first phase of an EPA sponsored research
project to develop a manual to investigate these connections
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b. IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Croup
cross-connections,
stormwater, dry-weather
flow, manual of practice
18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (This Report)
UNCLASSIFIED
20 SECURITY CLASS (This page)
UNCLASSIFIED	
21. NO. OF PAGES
£	
22. PRICE
EPA Form 2220-1 (R«v. 4-77) previous edition is obsolete

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