United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/SR-92/238 February 1993
EPA Project Summary
Investigation of Inappropriate
Pollutant Entries into Storm
Drainage Systems:
A User's Guide =
Robert Pitt, Melinda Lalor, Donald D. Adrian, Richard Field, and Donald Barb6
This User's Guide, summarized here,
is the result of a series of research
tasks (sponsored by the U.S. Environ-
mental Protection Agency) to develop
a procedure to investigate non-
stormwater entries into storm drainage
systems. Past projects have found that
dry-weather flows discharging from
storm drainage systems can contribute
significant pollutant loadings to receiv-
ing waters. These dry-weather flows
originate from many sources; the most
significant include sanitary wastewa-
ter, industrial and commercial pollut-
ant entries, failing septic tank systems,
and vehicle maintenance activities. Af-
ter identification of the outfalls that con-
tain polluted dry-weather flows, addi-
tional survey activities are needed to
locate and correct the non-stormwater
entries Into the storm drainage sys-
tems. If these loadings are Ignored (e.g.,
by only considering wet-weather
stormwater runoff), only limited Im-
provement in receiving water conditions
will occur with stormwater pollution
control programs.
This User's Guide contains informa-
tion on designing and conducting local
investigations to identify the types and
to estimate the magnitudes of these
non-stormwater entries.
This Project Summary was developed
by EPA's Risk Reduction Engineering
Laboratory, Cincinnati, OH, to announce
key findings of the research project
that Is fully documented In a separate
User's Guide of the same title (see
User's Guide ordering Information at
back).
Introduction
Current interest in illicit or inappropriate
connections to storm drainage systems is
an outgrowth of investigations into the
larger problem of determining the role of
urban stormwater runoff as a contributor
to receiving water quality problems. Water
discharged from stormwater drainage sys-
tems often includes waters from many non-
stormwater sources. A 1987 study in Sac-
ramento, CA, found that slightly less than
half the water discharged from a
stormwater drainage system was not di-
rectly attributable to runoff. Illicit and/or
inappropriate entries to the storm drain-
age system are likely sources of this dis-
charge and can account for a significant
amount of the pollutants discharged from
storm drainage systems.
Common sources of non-stormwater en-
tries include sanitary wastewater, automo-
bile maintenance and operation waste
products, laundry washwater, household
toxic substances, accident and spill waste
streams, runoff from excess irrigation, and
industrial sources of cooling waters, rinse
water, and other process wastewater. Al-
though these sources can enter the storm
drainage system through a variety of ways,
they generally result from either direct con-
nections (e.g., wastewater piping either
mistakenly or deliberately connected to
the storm drains) or indirect connections
(e.g., infiltration into the storm drain sys-
tem or spills collected by drain inlets).
Sources can be further divided into those
discharging continuously and those dis-
charging intermittently. Table 1 gives a
simple overview of typical pollutant sources
and their most likely characteristics.
Printed on Recycled Paper
-------
Table 1. Potential Inappropriate Entries into Storm Drainage Systems
Potential Source
Storm Drain How Contamination
Entry' Characteristics Category
Direct Indirect Conti- Inter- Patho- Nuis- Clear
nuous mittont genie/ ance
Toxic
Residential Areas:
Sanitary Wastewater
Septic tank effluent
Household chemicals
Laundry wastowater
Excess landscaping
watering
Leaking potable water
pipes
Commercial Areas:
Gasol/no filling station
Vohfclo
maintenance/repair
Laundry wastewater
Construction site
do-watering
Sanitary wastowater
Industrial Areas:
Leaking tanks and
pipes
Miscellaneous process
waters
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
x. X
X
X
X
X X
Xm most likely condition; x= may occur; blank = not very likely
* « direct, e.g., by piping; indirect, e.g., infiltration and spills
Figure 11s a simplified flow chart for the
detailed methodology contained in the
User's Guide. The initial phase of the in-
vestigative protocol includes the initial
mapping and surveys. These activities re-
quire minimal effort and result in little
chance of missing a seriously contami-
nated outfall. The initial activities are fol-
lowed by more detailed watershed sur-
veys to locate and correct the sources of
the contamination in the identified prob-
lem areas. After corrective action has been
taken, repeated outfall field surveys are
required to ensure that the outfalls remain
uncontaminated. Receiving water monitor-
ing should also be conducted to analyze
water quality improvements. If expected
Improvements are not noted, then addi-
tional contaminant sources are likely
present and additional outfall and water-
shed surveys are needed.
The User's Guide summarized here is
designed to provide information and guid-
ance to agencies planning or implement-
ing an Investigation of illicit entries to a
stormwater or wastewater drainage sys-
tem. This Is achieved by
1) Providing a methodology to identify
and describe potential sources of non-
stormwater pollutant entries into the
storm drainage system and
2) Describing an investigative procedure
that will allow a user first to determine
whether significant non-stormwater
entries are present in a storm drain,
and then to identify the potential type
of industrial, residential, or commercial
source responsible, as an aid to the
ultimate location of the source.
Procedures
The investigation steps described in the
User's Guide are: ,
• Drainage area mapping
• Tracer identification
• Field survey and data collection
• Analyses of data collected
• Categorization of outfalls
• Investigation and remediation
• Pollution prevention program
Mapping
The mapping exercise is carried out as
both a desktop operation by using exist-
ing information and with field visits to col-
lect further data and to confirm existing
information. The maps should provide com-
plete descriptions of the drainage areas
including outfall locations, watershed
boundaries for each outfall, critical land
use areas (mostly commercial and indus-
trial areas), permitted discharges to the
storm drainage system, city limits, major
streets, streams, etc. The User's Guide
discusses critical land use areas and lists
major industries and their potential to be
non-stormwater entry sources.
The drainage areas are ranked in the
order of their potential to cause problems,
which will allow priorities to be set for field
investigation of the outfalls. Note that all
outfalls will eventually require investiga-
tion and the mapping stage is important
because the entire investigation is based
on it.
Tracer Identification
To detect and identify non-stormwater
entries, the dry-weather outfall discharge
is analyzed for selected tracers (e.g., am-
monia, surfactants) which are found in the
potential contaminating sources. The se-
lected tracers should ideally be unique for
each potential non-stormwater contaminat-
ing source and exhibit the following prop-
erties:
• significant difference in concentrations
between possible pollutant sources,
• small variations in concentrations
within each likely pollutant source
category,
• a conservative behavior (i.e., no
significant concentration change due
to physical, chemical, or biological
processes), and
• ease of measurement with adequate
detection limits, good sensitivity, and
repeatability.
The User's Guide suggests tracers ap-
plicable for common pollutant sources (e.g,
sanitary wastewater, septic tank effluent,
laundry wastewater, and vehicle wash
wastewater as well as potable water and
"natural waters"). A non-stormwater entry
investigation may need to select additional
tracers specific to potential pollutant
sources, especially industries, in the study
area (e.g., major ions, specific heavy met-
als, etc.). For each selected tracer, the
concentration means and standard devia-
tions in all the potential source flows in
the drainage area are needed (use of
data from other drainage area investiga-
tions is not recommended).
Local data collected on tracers will be
essential to identify the sources in the
outfall discharge. It is important that the
tracer data be accurate; guidance is pro-
vided on representative sampling and the
number of samples required for valid data.
Field Survey
Field investigations are used to locate
and record all outfalls including outfalls
not previously identified from the mapping
exercise. During field investigations,
outfalls are physically inspected and
-------
United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati, OH 45268
EPA New Report Available
Investigation of Inappropriate
Pollutant Entries into Storm
Drainage Systems:
A Users Guide
You recently received a Project Summary (EPA/600/SR-92/238) with
the title shown above. An Important source for th® full report was
omitted from the ordering Information on the back page. Copies of the
full report entitled, "Investigation of Inappropriate Pollutant Entries
Into Storm Drainage Systems: A Users Guide" (EPA/600/R-92/238,
January 1993), are available free of charge as long as the supply lasts.
These copies can be ordered from:
ORD Publications
USEPA—CERIG-72
26 W. Martin Luther King Dr.
Cincinnati, OH 45268
Phone 513-569-7562
Fax 513-569-7566
-------
-------
Prepare area maps'
\t
\ Low 1
\ r
\lnvestigate after
high priority
\ r
\lnsufficient data I—
\ Outfall O.K.
>
V^ rlloriuZB
i
areas: ^>
\ High /
\
,j, Identify ror.t
ando
\
i
riving waters
utfalls
i
-Xj ^^^
1
f \i
\ Wo dry-weather / . — \ Sufficient data /
\ flow / \ 1
\
f
Check for intermittent flow
\
< no .x
f
^^
^^ yes Revisit, use automatic
J\<: <^lntermmmn IIUM^ * sampler, dam, etc.
\
S"
\
t
, \
f
\>
\ dear / \ Nuisance / \PathogenMoxicf
\ Possibly l<
water
i
1 \ \ Invesliga
xateclean\ \ pathoger
source \ \
\
\f
te after \ Relate to potential
ucnoxic \ » sourcg
\ f
\lnvestigate in drainage\
system to locate source \
Figure 1. Flow chart for investigation procedures.
-------
samples taken of any dry-weather flow for
analyses.
The field survey should, as a minimum,
include
• accurately locating outfalls and
assigning ID numbers;
• photographing outfalls;
• estimating outfall discharge flowrate
(or identifying likely intermittent
discharge);
• physically inspecting and recording
outfall characteristics including
discharge odor, color, turbidity,
floatable matter (solids, oil sheen,
etc.), temperature, deposits, stains,
vegetation affected by pollutants, and
damage to outfall structure; and
• collecting dry-weather discharge
samples for tracer analyses of specific
conductivity (can be field measured
with temperature), fluorides, hardness,
ammonia, potassium, surfactants,
fluorescence, and pH, (plus others,
depending on industrial activities).
Intermittent flows will be more difficult, if
not virtually impossible, to confirm and
sample. Additional field visits, use of auto-
matic samplers, and flow damming tech-
niques may prove successful for obtaining
samples of intermittent flows.
Analyses of Data Collected
Simple testing procedures are suggested
for analyzing the tracer parameters. Ex-
cept for temperature and specific conduc-
tivity measurements, the analyses should
bo carried out in a laboratory and not in
the field to ensure consistent results. The
laboratory need not be sophisticated; it
can be a room or trailer set up on a
temporary basis.
The recommended analytical procedures
for each tracer parameter are based on
the following criteria:
• appropriate detection limits,
• freedom from interferences,
• good analytical precision,
• tow cost, good equipment durability,
and
• reasonable operator training
requirements.
Guidance is also given on appropriate
levels of analytical detection and preci-
sion (repeatability) needed to achieve ac-
ceptable results.
Categorize Outfalls
Three levels of outfall discharges are
defined: (1) pathogenic or toxic pollution,
(2) nuisance and aquatic-life-threatening
pollution, and (3) unpolluted.
The pathogenic and toxic pollutants can
cause illness upon water contact or con-
sumption and cause significant water treat-
ment problems for downstream consum-
ers, especially if the pollutants are soluble
metal and organic toxicants. These pollut-
ants may originate from sanitary, com-
mercial, or industrial wastewater non-
stormwater entries. Other residential area
activities with a pollution potential include
household toxicant disposal, automobile
engine degreasing, and excessive use of
fertilizers and pesticides.
Nuisance and aquatic-life-threatening
pollutants include laundry wastewaters,
lawn irrigation runoff, vehicle washwaters,
construction-site dewatering, and washing
of concrete ready-mix trucks. These pol-
lutants can cause excessive algal growths,
tastes, and odors in downstream water
supplies, offensive coarse solids and
floatables, and noticeably colored, turbid
or odorous waters.
Clean water discharged through
stormwater outfalls can originate from natu-
ral springs feeding urban creeks that have
been converted to storm drains, infiltrating
groundwater, infiltrating domestic water
from waterline leaks, etc.
Comparing the collected dry-weather
outfall discharge data with potential source
flow data should allow outfalls to be clas-
sified. At the very least, outfalls with major
pollutant sources should be identified for
immediate remediation.
Investigation and Remediation
Drainage area investigations to locate
the source(s) of non-stormwater entries
can take a number of forms:
• in-depth watershed evaluation (e.g.,
evaluate whether source is likely to
be an individual industry or an
areawide problem such as general
failure of sanitary wastewater sewers);
• drainage system upstream surveys,
(e.g., tracer analyses, visual in-
spections, smoke and dye tests, and
TV surveys to trace the individual
source of the pollutant); and
• industrial and commercial site studies
(e.g., identify materials/chemicals used
and/or produced and whether the sites
discharge to a storm drainage
system).
Correction of the source, once located,
may not be as simple as disconnecting
the illicit entry. Widespread and numerous
pollutant entries may make a disconnec-
tion program impractical, or the existing
sanitary wastewater system may not have
the capacity to accept more flow. In these
cases the storm drainage system may
need to be classed as a combined sewer
system and have end-of-pipe treatment
applied.
Pollution Prevention Program
The goal of eliminating all non-
stormwater entries is unlikely to be
achieved; however, any action that pre-
vents future entries should be promoted.
Typical actions include:
• educating the public (industrial,
commercial, residential, and go,v-
ernmental) and
• developing zoning and ordinances.
Discussion
In addition to the above-outlined inves-
tigative steps, the User's Guide provides
background information in the form of dis-
cussions, tables, and checklists to assist
the user in identifying contaminated out-
fall discharges and potential sources, and
how to use the tracer data to estimate the
proportion of each contaminating source
flow in the outfall flow.
Two very simple hypothetical examples
illustrate the use of the User's Guide:
Example 1
Use of User's Guide Tables and
Check List
A mapping exercise identified the fol-
lowing industries in the stormwater drain-
age area: vegetable cannery, general food
store, fast food restaurant, cheese fac-
tory, used car dealer, cardboard box pro-
ducer, and a wood treatment company.
A field survey revealed an outfall with
constant dry-weather flow, a normal pH
(6), and low total dissolved solids concen-
trations (300 mg/L). Other outfall charac-
teristics included a strong odor of bleach,
no distinguishing color, moderate turbid-
ity, sawdust floatables, a small amount of
structural corrosion, and normal vegeta-
tion.
The significant characteristic in this situ-
ation is the sawdust floatables. The indus-
tries that could produce sawdust and have
dry-weather flow drainage to this pipe are
the cardboard box company and the wood
treatment company. According to SIC code
(from the User's Guide), the cardboard
box company would fall under the cat-
egory of "Paper Products" (SIC# 26)
whereas the wood treatment company
would be under that of "Lumber and Wood"
products (SIC# 24). A comparison of these
two industries (by their corresponding SIC
group numbers in the User's Guide), indi-
cates that a characteristic of the paper
industry is a strong potential for the odor
of bleach; wood products do not have any
particular smell indicated.
Based on these data, the most likely
industrial source of the non-stormwater
discharge would be the cardboard box
-------
company. The User's Guide under SIC#
26 indicates that there is a high potential
for direct connections in paper industries
under the categories of water usage and
illicit or inadvertent connections. At this
point, further investigations should be con-
ducted at the cardboard box company to
confirm the specific source.
Example 2
Use of Flow-Weighted Mixing
Calculations
This simplified example is structured on
a mass balance basis for just four poten-
tial flow sources and four tracers (P1, P2,
P3, P4). Table 2 shows the resulting set
of mass balance equations which can be
applied to each outfall sample.
A1 through A4 represent the fraction of
flow contributed from each potential flow
source. The "C" terms represent concen-
trations for each particular tracer (P1
through P4) within each flow source (1
through 4). The "m" terms represent the
tracer concentrations actually measured
in the outfall sample.
By using tracer concentration data in
the potential source flows (C) and in the
outfall discharge (m), the matrix can be
solved to indicate the fraction of flow con-
tributed from each possible flow source
(A1 through A4). More than four potential
sources can be included providing there
are data on an equal number of suitable
tracers.
A similar matrix method can also be
used to incorporate uncertainty in source
Table 2. Mass Balance Equation Matrix
Tracer
P1: (A1)((
P2: (A1)((
P3: (A1)((
P4: (A1)((
Potential Flow Sources
1.2 3
511) + (A2)(C21) •
012) + (A2)(C22) •
013) + (A2) (C23) •
014) + (A2) (C24) •
^ (A3) (C31) •
t- (A3) (C32) -,
i- (A3)(C33) -,
(• (A3) (C34) -,
Outfall
4 Quality
h (A4) (C41) =
t- (A4) (C42) =
^ (A4)(C43) =
^ (A4) (C44) =
ml
m2
m3
m4
area characteristics. This method results
in a range of predicted source flow contri-
butions.
Recommendations
This User's Guide should be used as
part of a comprehensive stormwater man-
agement plan that addresses all sources
of stormwater pollution. Correcting only
the most obvious pollutant entries is un-
likely to significantly improve the quality of
stormwater discharges or receiving wa-
ters.
A municipality planning an investigation
of inappropriate entries to it's storm drain-
age system needs to base this on local
conditions. This User's Guide describes
the issues in sufficient depth, with ex-
amples, to enable the design of a local
investigation.
All the applicable procedures described
in the User's Guide must be used to suc-
cessfully identify pollutant sources. For
example, attempting to reduce costs by
only examining a certain class of outfalls
or using inappropriate testing procedures
will significantly reduce the utility of the
testing program and result in inaccurate
data. Cursory data analyses are also likely
to result in inaccurate conclusions.
At an early stage, the economic and
practical advantages of designating the
storm drainage system as a combined
sewer (and applying end-of-pipe treatment)
should be considered. This early review
could save further investigation costs.
The methodology (appropriately modi-
fied) can also be applied to other types of
sewerage systems, such as combined and
separate sanitary sewerage systems, to
locate inappropriate entries, e.g., untreated
or toxic industrial wastewaters/wastes and
infiltration/inflow (into sanitary systems).
The User's Guide was submitted in par-
tial fulfillment of contracts numbered 68-
03-3255 and 68-C9-0033, by Foster-
Wheeler Enviresponse, Edison, NJ, and
cooperative agreement CR-816862 by the
Urban Waste Management and Research
Center of the University of New Orleans,
New Orleans, LA, under the sponsorship
of the U.S. Environmental Protection
Agency.
•U.S.Government Printing Office: 1993— 750-071/60197
-------
-------
-------
Robort Pitt and Melinda Lahrare with the University of Alabama at Birming-
ham, AL 35294; Donald D. Adrian is with Louisiana State University, Baton
Rouge, LA 70803; Donald Barbe is with the University of New Orleans, New
Orleans, LA 70148.
Richard Held is co-author and is the EPA Project Officer (see below).
The complete report, entitled "Investigation of Inappropriate Pollutant Entries
Into Storm Drainage Systems: A User's Guide," (OrderNo. PB93-131472/
AS; Cost: $19.50, subject to change) will be available only from
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Off her can be contacted at
Risk Reduction Engineering Laboratory
U.S. Environmental Protection Agency
Edison, NJ 08837-3679
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/600/R-92/238
------- |