NCS000429_Illicit Discharge Detection and Elimination Program Plan Draft_20220224

Illicit Discharge Detection
and Elimination Program
(IDDE)
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Great Place. G re a f Peop he. Great Promise.
October 2021

This plan is organized in two parts:
Section 1. The Basics of Illicit Discharges — This section describes the many different
sources and generating sites that can produce illicit discharges. The section also outlines
key concepts and terminology needed to understand illicit discharges, why they cause
water quality problems and the regulatory context for managing them.
Section 2. Gastonia's Illicit Discharge Program —This section presents the overall
framework for Gastonia's IDDE program by outlining key components of the program.
This section also defines program goals to guide efforts, as well as guidance on how to
measure and track progress toward their achievement and review and revisit goals and
make any needed adjustments. Finally, this section identifies the local implementation
steps for the program.
Section 1: The Basics of Illicit Discharges
Important Terminology and Key Concepts:
This section defines the terminology to help staff perform illicit discharge detective work.
Key concepts are presented to classify illicit discharges, generating sites and control
techniques.
Illicit Discharge: The term "illicit discharge" has many meanings in regulation and
practice; this plan employs this four-part definition.
1. Illicit discharges are defined as storm drains that have measurable flow during dry
weather containing pollutants and/or pathogens. A storm drain with measurable flow but
containing no pollutants is simply considered a discharge.

2. Each illicit discharge has a unique frequency, duration, composition and mode of entry
in the storm drain system.
3. Illicit discharges are frequently caused when the sewage disposal system interacts with
the storm drain system. In Gastonia, monitoring techniques are employed by Two Rivers
Utilities to rapidly trace sewage flows from the stream or outfall, and go back up the pipes.
4. Illicit discharges from types of activities and specific source areas and operations are
known as "generating sites." Knowledge about these generating sites is helpful to locate
and prevent non -sewage illicit discharges. Depending on the regulatory status of specific
generating sites, education, enforcement and other pollution prevention techniques can
be used to manage this class of illicit discharges.
Gastonia does allow some non -storm water discharges to the municipal separate storm system
(MS4), these discharges are firefighting activities and air conditioning condensate.
Storm Drain: A storm drain can be either an enclosed pipe or an open channel. From a
regulatory standpoint, major storm drains are defined as enclosed storm drain pipes with
a diameter of 36 inches or greater or open channels that drain more than 50 acres. For
industrial land uses, major storm drains are defined as enclosed storm drain pipes 12
inches or greater in diameter and open channels that drain more than two acres. Minor
storm drains are smaller than these thresholds. Both major and minor storm drains can
be a source of illicit discharges, and both merit investigation. Some "pipes" found in urban
areas may look like storm drains but actually serve other purposes. Examples include
foundation drains, weep holes, culverts, etc. These pipes are generally not considered
storm drains from a regulatory or practical standpoint. Small diameter "straight pipes,"
however, are a common source of illicit discharges in many communities and should be
investigated to determine if they are a pollutant source.
Not all dry weather storm drain flow contains pollutants or pathogens. Indeed, many
communities find that storm drains with dry weather flow are, in fact, relatively clean. Flow

in these drains may be derived from springs, groundwater seepage, or leaks from water
distribution pipes. Consequently, field testing and/or water quality sampling are often
needed to confirm whether pollutants are actually present in dry weather flow, in order to
classify them as an illicit discharge.
Discharge Frequency: The frequency of dry weather discharges in storm drains is
important, and can be classified as continuous, intermittent or transitory. Continuous
discharges occur most or all of the time, are usually easier to detect, and typically produce
the greatest pollutant load. Intermittent discharges occur over a shorter period of time
(e.g., a few hours per day or a relatively small number of days per year). Because they
are infrequent, intermittent discharges are hard to detect, but can still represent a serious
water quality problem, depending on their flow type. Transitory discharges occur rarely,
usually in response to a singular event such as an industrial spill, ruptured tank, sewer
break, transport accident or illegal dumping episode. These discharges are extremely
hard to detect with routine monitoring, but under the right conditions, can exert severe
water quality problems on downstream receiving waters.
Discharge Flow Types: Dry weather discharges are composed of one or more possible
flow types:
• Sewage and septage flows are produced from sewer pipes and septic systems.
• Wash water flows are generated from a wide variety of activities and operations.
Examples include discharges of gray water from homes, commercial carwash
wastewater, fleet washing, commercial laundry wastewater, and floor washing to shop
drains.
• Liquid wastes refers to a wide variety of flows, such as oil, paint, and process water
(radiator flushing water, plating bath wastewater, etc.) that enter the storm drain system.
• Tap water flows are derived from leaks and losses that occur during the distribution of
drinking water in the water supply system.
• Landscape irrigation flows occur when excess water used for residential or commercial

irrigation ends up in the storm drain system.
• Groundwater and spring water flows occur when the local water table rises above the
bottom elevation of the storm drain (known as the invert) and enters the storm drain
either through cracks and joints, or where open channels or pipes associated with the
MS4 may intercept seeps and springs.
Water quality testing can be used to conclusively identify flow types found in storm drains.
Testing can distinguish illicit flow types (sewage/septage, wash water and liquid wastes)
from cleaner discharges (tap water, landscape irrigation and ground water). Each flow
type has a distinct chemical fingerprint.
Mode of Entry
Illicit discharges can be further classified based on how they enter the storm drain system.
The mode of entry can either be direct or indirect.
Direct entry means that the discharge is directly connected to the storm drain pipe through a
sewage pipe, shop drain, or other kind of pipe. Direct entry usually produces discharges that are
continuous or intermittent. Direct entry usually occurs when two different kinds of "plumbing"
are improperly connected. The three main situations where this occurs are:
Sewage cross -connections: A sewer pipe that is improperly connected to the storm drain
system produces a continuous discharge of raw sewage to the pipe.
Straight pipe: This term refers to relatively small diameter pipes that intentionally bypass
the sanitary connection or septic drain fields, producing a direct discharge into open
channels or streams.
Industrial and commercial cross connections: These occur when a drain pipe is
improperly connected to the storm drain system producing a discharge of wash water,
process water or other inappropriate flows into the storm drain pipe. Older industrial areas
tend to have a higher potential for illicit cross -connections.
Sewage likely has the greatest potential to produce direct illicit discharges within
Gastonia. On a national scale, the most commonly reported sewage related direct

discharges are broken sanitary sewer lines, cross -connections, and straight pipe discharges.
Indirect entry means that flows generated outside the storm drain system enter through
storm drain inlets or by infiltrating through the joints of the pipe. Generally, indirect modes
of entry produce intermittent or transitory discharges, with the exception of groundwater
seepage. The five main modes of indirect entry for discharges include:
Groundwater seepage into the storm drain pipe: See page frequently occurs in storm
drains after long periods of above average rainfall. Seepage discharges can be either
continuous or intermittent, depending on the depth of the water table and the season.
Groundwater seepage usually consists of relatively clean water that is not an illicit
discharge by itself, but can mask other illicit discharges. If storm drains are located close
to sanitary sewers, groundwater seepage may intermingle with diluted sewage.
Spills that enter the storm drain system at an inlet: These transitory discharges occur
when a spill travels across an impervious surface and enters a storm drain inlet. Spills
typically occur at industrial, commercial and transport -related sites. A very common
example is an oil or gas spill from an accident that then travels across the road and into
the storm drain system.
Dumping a liquid: This type of transitory discharge is created when liquid wastes such as
oil, grease, paint, solvents, and various automotive fluids are dumped into the storm drain,
ditch, or stream. Liquid dumping occurs intermittently at sites that improperly dispose of
rinse water and wash water during maintenance and cleanup operations. A common
example is cleaning deep fryers in the parking lot of fast food operations.
Outdoor washing activities that create flow to a storm drain inlet: Outdoor washing may
or may not be an illicit discharge, depending on the nature of the generating site that
produces the wash water. For example, hosing off individual sidewalks and driveways
may not generate significant flows or pollutant loads. On the other hand, routine washing
of fueling areas, outdoor storage areas, and parking lots (power washing), and
construction equipment cleanouts may result in unacceptable pollutant loads.

Non -target irrigation from landscaping or lawns that reaches the storm drain system:
Irrigation can produce intermittent discharges from over -watering or misdirected
sprinklers that send tap water over impervious areas. In some instances, non -target
irrigation can produce unacceptable loads of nutrients, organic matter or pesticides. A
common example is a discharge from commercial landscaping areas adjacent to parking
lots or roads connected to the storm drain system.
Land Use and Potential Generating Sites: Land use can predict the potential for indirect
discharges, which are often intermittent or transitory. Many indirect discharges can be
identified and prevented using the concept of "generating sites," which are sites where
common operations can generate indirect discharges. Both research and program
experience indicates that a small subset of generating sites within a broader land use
category can produce most of the indirect discharges. Consequently, the density of
potential generating sites within a sub watershed may be a good indicator of the risk of
local illicit discharge problems. Some common generating sites within major land use
categories are listed and described below.
Gastonia intends to use land use as a general risk factor for illicit discharges. More specific risk
factors include the age of the sewer system, which helps define the physical integrity and
capacity of the pipe network, as well as age of development, which reveals the plumbing codes
and practices that existed when individual connections were made over time. The large number
of new connections and/or disconnections during these phases increases the probability of bad
plumbing. Gastonia intends to continue to work cooperatively with Two Rivers to identify the risk
of illicit sewage discharges.

Site Activities in Gastonia with the Highest Potential to Produce Illicit Discharges:
Residential: Car Washing, Driveway Cleaning, Septic System Maintenance, Swimming Pool
Discharges, Dumping/Spills and Lawn/Landscape Watering.
Commercial/Institutional/Municipal: Car Washes, Gas Stations/Auto Repair Shops, Oil Change
Shops, Building Maintenance (power washing), Landscaping/Grounds Care (irrigation), Public
Works Yard, Vehicle Fueling, Outdoor Material storage.
Commercial: Laundry/Dry Cleaning, Garden Centers/Nurseries, Restaurants, Dumping/Spills,
Road Maintenance, Vehicle Repair, Underground Storage Tanks.
Residential Generating Sites: Failing septic systems were the most common residential
discharge reported in 33% of IDDE programs surveyed nationally (CWP, 2002). In
addition, indirect residential discharges were also frequently detected in 20% of the IDDE
programs surveyed, which consisted of oil dumping, irrigation overflows, swimming pool
discharges, and car washing. Many indirect discharges are caused by common
residential behaviors and may not be classified as "illicit" even though they can contribute
to water quality problems.
Commercial Generating Sites: Typical commercial discharge generators included operations such
as outdoor washing; disposal of food wastes; car fueling, repair, and washing; parking lot power
washing; and poor dumpster management. It is important to note that not all businesses within
a generating category actually produce illicit discharges; generally, only a relatively small fraction
does. Consequently, on -site inspections of individual businesses are needed to confirm whether
a property is actually a generating site.
Institutional Generating Sites: Institutions such as schools and churches can be
generating sites if routine maintenance practices/operations create discharges from
parking lots and other areas. Some institutional sites have their own areas for fleet
maintenance, fueling, outdoor storage, and loading/unloading that can produce indirect

discharges.
Municipal Generating Sites: Municipal generating sites include operations that handle
solid waste, water, wastewater, street and storm drain maintenance, fleet washing, and
yard waste disposal. Transport -related areas such as town and state roads and rail lines
can also generate indirect discharges from spills, accidents and dumping.
1.2 Finding, Fixing, and Preventing Illicit Discharges
The purpose of Gastonia's IDDE program is to find, fix and prevent illicit discharges, and
develop a series of techniques to meet these objectives. These primary objectives are
briefly introduced below.
Finding Illicit Discharges
The highest current priorities for Gastonia's IDDE is to find any continuous and
intermittent sewage discharges to the storm drain system, and to perform reconnaissance
on high risk outfalls and generating areas. Observational and, where appropriate,
monitoring techniques will be used to find sewage discharges and then trace the problem
back to identify the ultimate generating site or connection. These techniques can be
classified into three major groups:
• Outfall Reconnaissance Inventory
• Indicator monitoring at stormwater outfalls and instream
• Tracking discharges to their source
Fixing Illicit Discharges
Once sewage discharges or other connections or discharging activities are discovered,
they can be fixed, repaired or eliminated. Fixing an illicit discharge can involve plumbing

repairs, behavioral changes/training, such as educating employees about proper disposal
of oil and grease at a restaurant or proper management of dumpsters, or infrastructure
repairs if there is a cross connection or faulty sewer line resulting in sewage entering the
stormwater conveyance system. It can also involve actions such as replacing or properly
maintaining a septic tank.
Preventing Illicit Discharges
The old adage "an ounce of prevention is worth a pound of cure" certainly applies to illicit
discharges. Transitory discharges from generating sites can be minimized through a
targeted education program, pollution prevention practices and well -executed spill
management and response plans.
Section 2: Gastonia"s IDDE Program
This section organizes and simplifies the basic tasks proposed for Gastonia's program.
Illicit Discharge Requirements in Gastonia's Stormwater Permit:
1. Maintain adequate legal authorities The City will annually review and revise the Cities IDDE
ordinance as necessary, and adopt any additional regulatory mechanisms that provide the City
with adequate legal authority to prohibit illicit connections and discharges and enforce the
approved IDDE Program.
2. Maintain storm water system inventory, including major outfalls that discharge to waters of
the State the City shall maintain a current map of the stormwater system that includes major
outfalls and receiving streams

3. Detect dry weather flows and investigate the source of all identified illicit discharges. The City
shall develop and implement a program for conducting dry weather flow field observations with
a written procedure for detecting and removing the sources of illicit discharges.
4. Track investigations and document illicit discharges. The City shall track all investigations and
document the date(s) the illicit discharge was observed; the results of the investigation; any
follow-up of the investigation; and the date the investigation was closed.
5. Provide Public Education the City will inform public employees, businesses, and the general
public of hazards associated with illegal discharges and improper disposal of waste.
Storm Sewer System Inventory: The program involves inventorying all storm drainage facilities
within the cities corporate limits.
All drainage structures (public and private) have been mapped, including surveying of all public
structures. Mapping has been enhanced as new digital and as -built information has become
available. The mapping program includes determination of the following: Horizontal and vertical
location of storm drainage structures and open end culverts, Sizes and types of the piping
connecting the drainage structures, Type and condition of storm drainage structures, all outfalls
greater than 36" diameter or draining greater than 50 acres are considered to be major outfalls.
As new field determinations of state regulated intermittent and perennial streams are
completed, the GIS database is updated, resulting in a connected and complete
stormwater/surface water database. Stormwater/Public Works staff have been inspecting storm
drainage structures for discoloration, odor, and the presence of liquids other than water or
anything else within the structure that would indicate past or intermittent illicit discharge.
Gastonia will continue to pursue steps to further document and understand the infrastructure.
Indirect or transitory discharges are difficult to catch through outfall screening.
Detection and Investigation:
The City has initiated detection and investigation procedures and will continue to explore ways
to improve upon these procedures. Successful detection and elimination programs have used a
wide array of techniques. Inspection and monitoring of the system often involves dry weather

flow investigations to determine the presence of illicit connections, the establishment of priority
sites that may need more extensive investigation, and a reporting system for the public to notify
officials of questionable activities. The City is focusing on the highest risk areas based on land use
and age of infrastructure. The highest risks are associated with commercial activities, leaking
sewer lines, and improper waste disposal.
Examples of training and a routine activity is physically inspecting the cities right-of-ways to
identify illicit discharges, working with Two Rivers to identify sanitary sewer connections and
respond to sewer overflows/spills and outfall reconnaissance surveys and stream walks.
Gastonia will seek IDDE reconnaissance support from local watershed groups as volunteer labor
is identified. The emphasis is to have as many "informed eyes" on potential illicit discharges in
the community as possible. Gastonia is fortunate to have citizen groups, including Keep Gastonia
Beautiful and the Catawba River Keepers, who can help observe outfalls and stream quality, and
support storm water education. All of these factors increase local watershed awareness and
stewardship.
Monitoring could be the most expensive component of the IDDE program, so it is extremely
important to understand existing discharges before committing to a particular monitoring
method or tracer.
Track investigations and document illicit discharges:
When illicit discharge problems are found, the next step is to trace them back to isolate the
specific source or improper connection that generates them. This component addresses locating
and documenting specific discharges.
Public Education:
Raising community wide awareness of storm water issues will assist the City in its efforts to
reduce pollutant run-off. Informative outreach and training programs will be developed to train
and inform residents, businesses, and town personnel of the following:
• Unpermitted practices

• Proper avenues for incident response
• Proper disposal of waste
• Irresponsible storm water management and the effect on the environment.
Gastonia will stress public health and safety benefits of sewage -free streams. Gastonia
will work with Two Rivers to publicize the danger of sewage discharges, and notify the
public about the discharges that need to be prevented or corrected.
Public Reporting Mechanism:
Clear and accessible reporting and communication protocol for the program is paramount to
successful implementation. The Cities website has this information. Gastonia will integrate wide
dissemination of this information into Public Education and Outreach efforts, e.g., through social
media, newsflashes, community events, and direct outreach to important sectors and community
stakeholders. Clear information is provided to help point the responding party to whether the
first point of contact should be emergency response (911/Fire and Rescue), Two Rivers, Public
Works, Planning within City government as well as other public agencies. Stormwater has
established a hotline number, email address, and an online form for reporting Stormwater issued
including IDDE.
Enforcement:
The City will continue to enforce its ordinance. Enforcement support is provided by Building
Inspectors, Zoning staff, the Police Department, and City Attorney.
Gastonia will pursue detection and elimination of continuous sewage discharges first. Effective
programs place a premium on keeping sewage out of the storm drain system. Continuous sewage
discharges pose the greatest threat to water quality and public health, produce large pollutant
loads, and can generally be permanently corrected when the offending connection is found.
Intermittent, transitory, or indirect discharges are harder to detect, and more difficult to fix.

Gastonia will educate a broad audience about illicit discharges. Illicit discharge control is a
somewhat confusing program to many staff, the public, elected officials, and other local agencies.
The success of this program will in large part be a function of the success in educating all four
groups.
Gastonia will cross -train local inspectors and emergency responders to recognize discharges and
report them for enforcement. Gastonia's program will ensure that, building, zoning, water and
wastewater, health, and erosion control inspectors and fire and rescue staff understand illicit
discharges and know whom to contact locally for enforcement.
Gastonia will target limited storm water education dollars. Gastonia has limited resources to
perform the amount of storm water education needed to reduce indirect and transitory
discharges. Consequently, Gastonia will target discharges of concern, and focus on the sub
watersheds, neighborhoods and sectors most likely to generate them. Gastonia will work
collaboratively with the Clean Water Education Partnership, local media, Advisory Boards, Two
Rivers and citizen's groups to maximize the effectiveness and cost effectiveness of education
efforts.
Gastonia will calibrate resources to the magnitude of the illicit discharge problem. Gastonia will
get a better handle on the actual severity of illicit discharge problems over time. The program is
therefore designed to be flexible and adaptive, and will shift resources to the management
measures that will reduce the greatest amount of pollution.
Gastonia will think of illicit discharge prevention as a tool of watershed restoration. Discharge
prevention is considered one of the seven primary practices used to restore urban watersheds.
Effective programs integrate illicit discharge control as a part of a comprehensive effort to restore
local watersheds.

Program Goals and Implementation Strategies:
This section discusses the goals and performance milestones to measure progress in Gastonia's
IDDE program implementation, and most appropriate and cost effective strategies to find, fix and
prevent illicit discharges. The goals and strategies ensure that scarce local resources are allocated
to address the most severe illicit discharge problems that cause the greatest water quality
problems in the community.
IDDE program goals:
• keeping raw or poorly -treated sewage out of streams
• meeting bacteria water quality standards during dry weather flows
• reducing toxicant, nutrient and other pollutant discharges to streams to restore the abundance
and diversity of aquatic biota and help meet established TMDLs
Based on knowledge of stressors to local waterbodies, Gastonia's IDDE program is seen as one of
multiple watershed protection and restoration programs. Over time as staff determines the
degree to which illicit discharges contribute to impaired water quality, resources (both time and
money) can be shifted amongst all the programs to most effectively meet the water resource
goals.
Perhaps the most important implementation strategy is targeting —screening, education and
enforcement efforts should always be focused on the catchments or generating sites with the
greatest Illicit Discharge potential (IDP). Ongoing adaptability is also an important program
objective.
Technical Approach to Monitoring for IDDE program:
The section includes a flow chart approach that utilizes chemical indicators. The section provides
specific information on proper safety, handling, and disposal procedures. Simple and more
sophisticated methods for interpreting monitoring data are discussed, along with comparative
cost information. From a program management standpoint, core issues need to be considered
during the design of the monitoring strategy. The indicator monitoring strategy should be

concentrated primarily on continuous and intermittent discharges, and can be adapted to isolate
the specific flow type found in a discharge. The discussion below presents an overall monitoring
design framework that organizes some of the key indicators and monitoring techniques that may
be needed. In general, different indicators and monitoring methods are used depending on
whether flow is present at an outfall or not. The basic framework should be adapted to reflect
the unique discharge problems and analytical capabilities of individual communities. Some of the
recommended monitoring strategies are discussed below. The preferred method to test flowing
outfalls is the flow chart method that uses a small set of indicator parameters to determine
whether a discharge is clean or dirty, and predicts its flow type. The flow chart method is
particularly suited to distinguish sewage and wash water flow types. More complex methods are
available for industrial sites, but are not included herein.
The Flow Chart Method:
Gastonia will test the "Flow Chart Method", which is recommended for most Phase II
communities. The Flow Chart Method can distinguish four major discharge types found in
residential watersheds, including sewage and wash water flows that are normally the most
common illicit discharges. Much of the data supporting the method were collected in Alabama
and other regions, and some local adjustment may be needed in some communities. The Flow
Chart Method is recommended because it is a relatively simple technique that analyzes four or
five indicator parameters that are safe, reliable and inexpensive to measure.
Step 1: Separate clean flows from contaminated flows using detergents.
The first step evaluates whether the discharge is derived from sewage or wash water sources,
based on the presence of detergents. Boron and/or surfactants are used as the primary detergent
indicator, and values of boron or surfactants that exceed 0.35 mg/L and 0.25 mg/L, respectively,
signal that the discharge is contaminated by sewage or wash water.

Step 2: Separate wash water from wastewater using the Ammonia/Potassium ratio.
If the discharge contains detergents, the next step is to determine whether they are derived from
sewage or wash water, using the ammonia to potassium ratios. A ratio greater than one suggests
sewage contamination, whereas ratios less than one indicate wash water contamination.
Step 3: Separate tap water from natural water.
If the sample is free of detergents, the next step is to determine if the flow is derived from
spring/groundwater or comes from tap water. The benchmark indicator used in this step is
fluoride, with concentrations exceeding 0.60 mg/L indicating that potable water is the source.
Fluoride levels between 0.13 and 0.6 may indicate non -target irrigation water. The purpose of
determining the source of a relatively "clean discharge" is that it can point to water line breaks,
outdoor washing, non -target irrigation and other uses of municipal water that generate flows
with pollutants.
While the flow chart method and indicators will provide a foundation, Gastonia may investigate
other indicators to supplement this method. The following is a list of indicators that Gastonia will
consider in developing IDDE monitoring capabilities.
Acidity — refers to the capability of a sample to neutralize a base. Indicates corrosive properties.
Not to be confused with pH.
Alkalinity — refers to the capability of a sample to neutralize an acid. A measure of buffering
capacity. Not to be confused with pH.
Ammonia (NH3 / NH4 + ) — Indicator of sanitary sewer leaks but also widely used for fertilizer,
disinfectant, and cleanser. Also a combustion product. Readily transformed by bacteria to nitrite.
Boron (B+ ) — borate is used for "color -safe bleach" as well as a pool -chemical disinfectant, boric
acid is used as a mild antiseptic and for organic insectides. Borate is a good laundry indicator
especially when phosphate -free detergents are used.

Caffeine — the D+Caf test goes down supposedly to 3.5mg/L —enough to detect whether your
decaf coffee/tea is really decaf. This could be used as a potential indicator of sanitary sewer leaks,
however, the existing method seems to be confusing to read and not very accurate. Gastonia
may want to find a lab that could do caffeine analysis, as a check for suspected sanitary sewer
leaks, but right now there are no field methods available.
Chlorine — indicators of drinking water but also laundry detergent/bleach, pool chemicals
(Chlorine Dioxide, hypochlorite, and chlorine gas used for water treatment, Hypochlorite is also
laundry bleach). It is possible to measure free available chlorine, chlorine dioxide, hypochlorite
ion, chloramines, and total available residual chlorine.
Free available residual chlorine - that portion of the total available residual chlorine composed
of dissolved chlorine gas c12), hypochlorous acid (HOCI), and/or hypochlorite ion (OCI-) remaining
in water after chlorination. This does not include chlorine that has combined with ammonia,
nitrogen, or other compounds.
Total available residual chlorine — the amount of available chlorine remaining after a given
contact time. The sum of the combined available residual chlorine and the free available residual
chlorine.
Combined available chlorine — chloramines or chlorine compounds that disinfect
Coliform/Bacteria — Indicators of sanitary sewer leaks, but also other bacterial sources. There's
so many different ways to screen for bacteria, including type. For example: Lamotte has indicator
kits for coliform, aerobic bacteria, sulfate -reducing bacteria, bacteria and fungi, and generic
bacteria. Lamotte has kits specifically for testing activity/population size of sulfate -reducing
bacteria, slime -forming bacteria, iron -related bacteria, heterotrophic aerobic bacteria, micro -
algae, fluorescent pseudomonas, denitrifying bacteria, and nitrifying bacteria.
Conductivity — Conductivity measures everything dissolved in water (as to its conductance). This
can be very useful when there is a high load of solutes, probably indicative of some kind of non -
natural source, but may include analytics we can't detect or just too many of them.

Detergents/Surfactants — they're not exactly the same thing, but with regard to water testing
they are both measuring the presence of products used for cleaning/washing everything from
body soap, laundry detergent, car wash, etc. Even "bio-degradable" products have them in them.
Detergents and surfactants are extremely toxic to aquatic life.
Fluoride (F- ) — an indicator of drinking water because of fluoridation, concentrations above
0.25mg/L are suggested for differentiating between a natural water source and tap or irrigation
water. Dilute hydrofluoric acid (HF) is used for glass etching and recently for wheel cleaner
compounds.
Forma ldehyde/GIuteraldehyde — Formaldehyde is naturally occurring in combustion products.
Both aldehydes are used as commercial, health care, and industrial disinfectants (these are what
we are most likely to see being dumped), as well as for preserving animal tissue.
Hardness — is a measure of scaling minerals, but also includes an aspect of alkalinity (carbonate
minerals). Primarily calcium, magnesium, iron, and manganese. Our ground water is fairly soft,
so a hard water sample is indicative of some other source.
Nitrate (NO3 - ) — Primary source is through fertilizers, although ammonia is converted to nitrate
through nitrite. Indicator of fertilizer wash -off, but also metabolized sanitary sewer water.
Nitrite (NO2 - ) — Primary source is metabolized ammonia/ammonium. Can be used to detect
sanitary sewer waters that may have filtered through soil. pH —indicator of relative
acidity/alkalinity. Unusually acidic or alkaline values can help identify a potential pollution
problem and source.
Phosphate — Orthophosphates are bioavailable and present in sewage and fertilizers.
Metaphosphates have been used in detergents and boiler waters (but have been replaced by
zeolites). Orthophosphates are readily measured, whereas metaphosphates require processing.
Total inorganic (ortho and meta) must be boiled with acid prior to processing
Potassium (K+ ) — used to distinguish between sanitary sewer contamination and wash water
contamination. It's also present in weed killers and fertilizers.

Field Inspection Checklist:
✓ Monitoring test kits
✓ Test meters (pH, conductivity, turbidity)
✓ Protective gloves for handling chemicals
✓ Sunscreen, poison ivy cream, first aid kit
✓ Safety goggles, hard hat, closed -toes shoes
✓ Container for bringing back liquid reagent wastes from the field
✓ Extendable pole with attached sampling cup
✓ Paper towels or rags
✓ Field forms
✓ Storm drain, stream and street maps
✓ Tape measure
✓ Standard camera
✓ Cell Phone
✓ GIS capable smart phone or tablet
✓ Contact information of emergency response personnel in case of spills
✓ Marking paint/flagging
✓ Caution tape or cones
✓ Clip Board
✓ Flashlight
✓ Manhole Pick
✓ Inspection notification letter documenting legal authority to gain access to property
during field inspection

Physical Indicators:
Color:
Tan to light brown: Suspended sediments, common after rainfall and runoff from
construction.
Tea/coffee: Dissolved or decaying organic matter, usually from soil or leaves. Commonly
associated with tree overhangs, woodlands, or swampy areas.
Milky white: Paint, lime, grease, concrete. Swimming pool filter backwash
Dirty dishwater gray: wastewater, musty odor
Milky gray -black: Raw sewage discharge or other oxygen
Clear black: sulfuric acid spill
Dark red, purple, blue, black: fabric dyes, inks from paper, cardboard manufacturers.
Odor:
Rotten eggs/hydrogen sulfide: Raw sewage, decomposing organic matter, lack of oxygen.
Chlorine: Wastewater treatment plant discharges, swimming pool overflow, industrial
discharges.
Sharp, pungent odor: Chemicals or pesticides.
Musty odor: Partially treated sewage, livestock waste.
Gasoline: industrial discharge, illegal dumping of wastes.
Sweet, fruity: Commercial wash water.
Sewage, Sheens and Surface Scum:
Contaminated flows may contain floatable solids or liquids. Sewage, oil sheen, and
suds/foam are examples of floatable indicators. Trash and debris, although more typically
known as "floatables," are not generally indicators of illicit flow.
• Sheens can be naturally -produced or synthetic; oil sheens are often mistaken for naturally -
produced sheen.
• Sheen from bacteria forms a sheet -like film that breaks if disturbed. Suds should be rated
based on their foaminess and staying power.

• Suds that travel several feet before breaking up should be considered as a possible illicit
discharge.
• In some cases, foam and suds can give off an odor.
• A strong organic or sewage -like odor can indicate a sanitary sewer leak or overflow.
• A fragrant or sweet smelling odor can indicate the presence of laundry water or similar
wash waters.
Surface Scum:
Tan Foam: Usually associated with high flow or wave action; wind action plus flow churns
water containing organic materials causing harmless foam; produces small patches to very
large clumps.
White Foam: Sometimes patchy or covering wide area around wastewater outfall, thin and
billowy, mostly due to soap.
Yellow, brown, black film: Pine, cedar, and oak pollens form film on surface, especially in
ponds, backwater areas, or slow moving water in streams.
Rainbow film: If a swirling pattern, then likely oil or other fuel type. Check for petroleum
odor. If sheet -like and cracks if disturbed, then it is natural.
Outfall Condition:
The physical condition of an outfall can provide strong clues about the history of discharges
passing through it. Over time, intermittent discharges can cause outfall damage or leave
behind remnants in the form of deposits or stains which can help an inspector determine
what type of discharge traveled through the area. Field inspectors should document that a
deposit or stain is present even if there is no dry weather discharge observed.
Structural Damage: Cracked, deteriorated concrete or peeling surface paint at an outfall
usually indicates the presence of contaminated discharges. Contaminants causing this type
of damage are usually very acidic or basic (alkaline) and originate from industrial processes.
Deposits and Stains: Staining may be any color but is characteristically different from the
outfall. Residues can contain fragments of floatable substances. Gray -white deposits can be

from illegal dumping of concrete truck washouts. Crystalline powder can indicate the
discharge of fertilizer wastes.
Biological Indicators:
Biological indicators include things that live and grow. The biological indicators that should
be investigated during a field inspection are: the condition of the surrounding vegetation,
algae growth, amount and types of bacteria, fish kills, and the presence or absence of certain
aquatic organisms.
Vegetation: Seasonal and recent weather conditions should be considered to accurately
determine if the vegetation near an outfall is normal or abnormal. Increased or inhibited
plant growth, as well as dead and decaying plants, near stormwater outfalls is often a sign of
pollution.
Algae: An overabundance of nutrients can cause elevated plant growth or algae blooms.
During an algae bloom, the water body typically becomes a pea-green color; however, the
color depends on the dominant species of algae present.
Bacteria: The amount and types of bacteria present can be extremely significant. Bacteria
can be associated with inadequately treated sewage, sanitary sewer overflows, improperly
managed waste from livestock, failing septic systems, and pets and wildlife (e.g., birds
nesting under a bridge). Although some types of bacteria are visible to the naked eye — such
as sewage fungus or natural sheen, counts for indicators like E. coli are done in the
laboratory.
Fish kills: Fish kills can be caused by a wide variety of factors including a decrease in dissolved
oxygen, infectious disease, a rise in water temperature, toxic algae blooms, parasites, and
bacterial or viral infections. The loss of a single fish is typically a natural occurrence and is
not usually a cause for concern.
Presence or Absence of Aquatic life: The presence or absence of aquatic life in and around
a water body can be an indicator of the health of the water body. Field inspectors should
document whether or not they observe aquatic life at the time of inspection.

Storm Drain Network Investigations:
This technique involves:
• Inspecting manholes in a storm drain system by using chemical and physical indicators to
isolate discharges to specific segments of the network.
• Identifying where to inspect the network and what indicators to use to determine if a
manhole is clean or contaminated.
• Developing a strategic plan for inspecting the pipe network.
There are three basic approaches to on -site investigations that will help determine the actual
source of an illicit discharge: dye, video, and smoke testing. Note: these techniques should
be used when conducting a follow-up investigation once an illicit discharge has been found.
Refer to the CWP IDDE manual for more detailed information on how to use these
techniques. Before performing any dye or smoke testing, make sure to contact other city
departments, spill response agencies, and downstream municipalities to let them know
when and where these activities will take place.