6_NCS000414_IDDE Plan_20210708

Illicit Discharge Detection &Elimination
(IDDE) Plan
TOWN OF CHAPEL HILL
Stormwater Management Division
Public Works Department
May 2021

Town of Chapel Hill IDDE Plan
NPDES Permit NCS000414
May 2021
Table of Contents
1 INTRODUCTION..................................................................................................................................... 6
1.1 Purpose.........................................................................................................................................
6
1.2 Background...................................................................................................................................6
2 PROGRAM GOALS, IMPLEMENTATION STRATEGIES, AND EVALUATION.............................................7
3 TERMINOLOGY AND KEY CONCEPTS.....................................................................................................8
3.1 What is an Illicit Discharge?..........................................................................................................8
3.2 What is an MS4 and Storm Drainage System?..............................................................................9
3.3 Characteristics of Illicit Discharges..............................................................................................11
3.4 Tools for Identifying Illicit Discharges.........................................................................................12
4 REGULATORY AUTHORITY...................................................................................................................12
5 STORM SEWER SYSTEM MAPPING......................................................................................................13
6 PREVENTING ILLICIT DISCHARGES.......................................................................................................14
6.1 Public Education and Involvement.............................................................................................14
6.2 Business Education and Outreach..............................................................................................14
6.3 Municipal Good Housekeeping and Pollution Prevention..........................................................15
7 COMMON POLLUTION PROBLEMS.....................................................................................................15
7.1 Sediment Discharge....................................................................................................................15
7.2 Waste Management...................................................................................................................17
7.3 Yard Waste..................................................................................................................................19
7.4 Hazardous Waste........................................................................................................................19
7.5 Outdoor Washing Activities........................................................................................................
21
7.6 Water Main Breaks & Waterline Flushing...................................................................................21
7.7 Sanitary Sewer & Septic System Discharges...............................................................................22
7.8 Pool Discharges...........................................................................................................................23
8 REPORTING AN ILLICIT DISCHARGE OR WATER QUALITY ISSUE.........................................................24
8.1 How to Report an Illicit Discharge or Connection.......................................................................24
8.1.1 Hotline.................................................................................................................................24
8.1.2 Email....................................................................................................................................24
8.1.3 SeeClickFix...........................................................................................................................24
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8.1.4 Town of Chapel Hill Report a Violation Website.................................................................24
8.2 What to Report........................................................................................................................... 24
8.3 Reporting Major Spills to State Regulators.................................................................................25
8.3.1 Sanitary Sewer Collection System Overflows (SSOs)..........................................................25
8.3.2 Oil Spills...............................................................................................................................25
8.3.3 Hazardous Substance Spills.................................................................................................26
8.3.4 Fish Kills...............................................................................................................................26
9 FINDING ILLICIT DISCHARGES..............................................................................................................26
9.1.1 Staff Field Observations......................................................................................................26
9.1.2 Water Quality Monitoring...................................................................................................26
9.1.3 Dry Weather Outfall Screening...........................................................................................27
10 ISOLATING & FIXING ILLICIT DISCHARGES.......................................................................................27
10.1 Desktop Assessment of Illicit Discharge Potential......................................................................27
10.2 Tracing an Illicit Discharge..........................................................................................................28
10.2.1 Storm Drain Network Investigation....................................................................................28
10.2.1.1 Working progressively up the network.......................................................................28
10.2.1.2 Working progressively down the network..................................................................28
10.2.2 Tools for tracing an illicit discharge....................................................................................28
10.3 Fixing Illicit Discharges................................................................................................................28
11 IDDE INCIDENT/INVESTIGATION TRACKING AND DOCUMENTATION............................................29
11.1 IDDE Tracking Database..............................................................................................................29
11.2 IDDE Incident Folders..................................................................................................................30
12 ENFORCEMENT...............................................................................................................................30
12.1 Notices of Violation.....................................................................................................................
31
12.1.1 Eliminating the Source of an Illicit Discharge or Connection..............................................31
12.1.2 Confirmation of Removal....................................................................................................31
12.2 Civil Penalties and Other Remedies............................................................................................31
12.2.1 Criteria to Determine Amount of Penalties........................................................................32
12.2.2 Procedure for Issuance of Civil Penalties............................................................................33
12.2.3 Other Remedies..................................................................................................................33
12.3 Appeals........................................................................................................................................33
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13 COORDINATING AGENCIES & CONTACT INFORMATION................................................................33
13.1 Chapel Hill Building and Development Services.........................................................................34
13.2 Town of Carrboro........................................................................................................................34
13.3 University of North Carolina at Chapel Hill - Stormwater & Energy Services .............................35
13.4 Orange County Environmental Health........................................................................................35
13.5 OWASA........................................................................................................................................35
13.6 Orange County Erosion and Sediment Control (E&SC Ordinance).............................................35
14 REFERENCES....................................................................................................................................36
15 APPENDIX A: Dry Weather Screening Standard Operating Procedures (SOP)................................36
List of Tables
Table 1. Existing GIS Datasets for IDDE Investigations and Prioritization...................................................13
Table 2. IDDE Database field names and descriptions................................................................................29
Table 3. List of Contacts for Town Staff & Coordinating Agencies.............................................................34
List of Figures
Figure 1. Sediment discharge examples.....................................................................................................16
Figure 2. Typical sediment discharge sources.............................................................................................16
Figure 3. Trash/dumping examples............................................................................................................18
Figure 4. Yard waste examples...................................................................................................................19
Figure 5. Hazardous waste examples..........................................................................................................20
Figure 6. Outdoor washing examples.........................................................................................................21
Figure 7. Waterline break examples...........................................................................................................22
Figure 8. Sanitary sewage discharge sources..............................................................................................22
Figure 9. Pool discharge examples..............................................................................................................23
Figure 10. Summary of civil penalties that may be assessed for first time and repeat offenders, per the
Town's IDDE Ordinance...............................................................................................................................32
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List of Common Abbreviations
May 2021
Acronym
Meaning
CWP
Center for Watershed Protection
E&SC
Erosion & Sedimentation Control
FEMA
Federal Emergency Management Agency
GIS
Geographic Information System
GPS
Global Positioning System
IDDE
Illicit Discharge Detection and Elimination
MS4
Municipal Separate Storm Sewer System
NCDEQ
North Carolina Department of Environmental Quality
NCDEMLR
North Carolina Division of Energy, Mineral, and Land Resources
NCDOT
North Carolina Department of Transportation
NCDWR
North Carolina Division of Water Resources
NOV
Notice of Violation
NPDES
National Pollutant Discharge Elimination System
ORI
Outfall Reconnaissance Inventory
OWASA
Orange Water & Sewer Authority
RRO
Raleigh Regional Office (NCDEQ)
SCM
Stormwater Control Measure
SOP
Standard Operating Procedures
SWMP
Stormwater Management Plan
UNC-CH
University of North Carolina — Chapel Hill
YYYYMMDD
Year Month Day format (e.g., 20210514 = May 14, 2021)
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1 INTRODUCTION
1.1 PURPOSE
This document describes the Town of Chapel Hill's Illicit Discharge Detection and Elimination (IDDE)
Program. The IDDE Plan covers the topics of detection, investigation, documentation, and enforcement
to remove non-stormwater (illicit) discharges or connections that carry pollutants into the Town's
stormwater drainage system, and includes general guidelines and specific standard operating procedures
(SOP) for Town of Chapel Hill staff conducting illicit discharge and water quality complaint investigations.
The IDDE Plan is part of a series of guidelines and procedures required for the implementation of the
Town's Stormwater Management Plan and compliance with the Town's National Pollutant Discharge
Elimination System (NPDES) Municipal Separate Storm Sewer (MS4) permit.
1.2 BACKGROUND
Prior to adoption of federal Stormwater regulations, studies showed that illicit discharges account for a
significant amount of the pollutants discharged from stormwater drainage systems. For many pollutants,
the annual mass discharge was found to be dominated by dry -weather flows, rather than stormwater
runoff (EPA Publication No. 600-R-92-238). These early studies also found that areas of older land
development generally have worse water quality than areas developed within the last several decades, in
part because of aging infrastructure, different building practices, and different materials of construction
than areas constructed after the mid-1940s.
In response to those studies, the EPA promulgated two phases of regulations, including an expanded
National Pollutant Discharge Elimination System (NPDES) permitting program, requiring municipalities to
take steps in reducing stormwater pollution from their storm drainage systems.
The Town of Chapel Hill was first issued a NPDES Municipal Separate Storm Sewer System (MS4) Phase II
permit ("MS4 Stormwater Permit") (NCS000414) in 2005, which included specific requirements to
implement a program to identify/detect and eliminate non-stormwater discharges that are a source of
water quality pollution. The Town's MS4 Stormwater Permit must be renewed every five (5) years. The
most current MS4 Stormwater Permit became effective on February 27, 2017, and expires at midnight
on February 26, 2022.
The Town's MS4 Stormwater Permit prescribes the following objectives for an IDDE Program:
• implement and enforce an IDDE program;
• maintain a storm sewer system map, showing major outfalls and names and locations of receiving
waters;
• prohibit, through ordinance or other regulatory mechanism, non-stormwater discharges (except
as allowed in the permit) and implement appropriate enforcement procedures and actions;
• implement a plan to detect and address non-stormwater discharges, including illegal dumping, to
the MS4;
• inform public employees, businesses and the general public of hazards associated with illicit
discharges and improper disposal of waste; and
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address specific categories of non-stormwater discharges or flows that are otherwise considered
allowed/exempt if the Town identifies them as significant contributors of pollutants to the MS4.
Preventing spills and eliminating illicit discharges and connections is a cost-effective means of restoring
and protecting water quality. Investigations are an essential component of a comprehensive illicit
discharge control program, and rely on an educated public and municipal staff to identify possible
pollution sources for investigation; they also provide an opportunity for staff to interact with and further
educate the public and municipal staff about adverse impacts of illicit discharges and illicit connections
on water quality. Increased awareness of illicit discharges results in more effective reporting by the public
and municipal staff, aiding the Town's efforts to protect water quality. Once an investigation identifies a
violation, education and enforcement are used to eliminate sources and to require illicit discharges to be
eliminated.
2 PROGRAM GOALS, IMPLEMENTATION STRATEGIES, AND
EVALUATION
The overall goals of the Town's IDDE Program include program administration and documentation, outfall
assessment, preventing illicit discharges, and finding and fixing illicit discharges. The Town maintains an
IDDE program that includes a hotline for reporting illicit discharges, a stormwater conveyance system map
(infrastructure and receiving streams), a regulatory mechanism (IDDE Ordinance), and procedures for
detection and elimination as well as enforcement. The Town actively provides education and outreach to
the Town's residents and businesses, including targeted audiences, and has been developing a sustainable
staff training program. A tracking and reporting system is in place, and IDDE efforts are coordinated and
communicated with other affected agencies, including adjacent MS4 communities.
The Town of Chapel Hill Stormwater Management Plan (SWMP) provides an overview of the IDDE
Program, which includes best management practices (BMPs) the Town implements to achieve measurable
goals and objectives, and provides a schedule for implementation and annual reporting metrics for each
measurable goal.
The effectiveness of the Town's IDDE program can be evaluated by reviewing the program and progress
made toward meeting the program's measurable goals on an annual basis. The Town has developed a
comprehensive IDDE tracking database and filing system which is used to support enforcement actions,
help identify hot spots, chronic violators, and common pollution sources, and to provide information for
annual reporting. Evaluation of the Town's GIS database of stormwater infrastructure and receiving
streams, as well as water quality monitoring data, helps staff identify gaps in mapping that should be
addressed as well as identify major outfalls that should be prioritized for dry weather screening. This
information can also be used to recommend program revisions and staff work plans, as well as identify
staff and funding needs.
Please refer to the most current SWMP located on the Stormwater Management website for the most up
to date information on BMPs, measurable goals, schedule of implementation, and metrics used for
program evaluation.
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3 TERMINOLOGY AND KEY CONCEPTS
This section includes important terms and key concepts used to describe illicit discharges and the Town's
IDDE program.
3.1 WHAT IS AN ILLICIT DISCHARGE?
The term "illicit discharge" has meanings in both regulation and practice. In general, an illicit discharge is
any discharge to a MS4 that is not composed entirely of stormwater, except those discharges that are
considered "allowable." The following terms for illicit discharge, illicit connection, and allowable non-
stormwater discharges are defined in the Town's Illicit Discharge Ordinance (Town Code of Ordinances,
Section 23, Article V).
Illicit discharge: any direct or indirect non-stormwater discharge or contaminated stormwater
discharge to the stormwater drainage system, including the MS4 and waters of the State, except
as exempted in section 23-84 of the IDDE Ordinance (see "allowable non-stormwater discharges"
below).
Illicit connection:
(1) Any drain or conveyance, whether on the surface or subsurface, which allows an illicit
discharge to enter the stormwater drainage system, including but not limited to
conveyances which allow any non-stormwater discharge including sewage, wastewater,
and wash water to enter the stormwater drainage system and any connections to the
stormwater drainage system from indoor drains and sinks, elevator sump pumps, or
interior parking area drains, regardless of whether said drain has been previously allowed,
permitted, or approved by the town or other governmental entity.
(2) Any drain, pipe, ditch or other conveyance connected to the stormwater drainage system
which has not been documented in construction or site plans, a building permit, maps, or
other equivalent records and approved by the town or other governmental entity.
Allowable Non-stormwater Discharges: The following are categories of non-stormwater
discharges that allowed per the Town's IDDE Ordinance provided the discharge does not
significantly impact water quality or cause or contribute to violations of water quality standards
and are discharged in accordance with best management practices in the Town's Engineering
Design Manual:
• Water line flushing.
• Landscape irrigation.
• Diverted stream flows.
• Rising groundwaters.
• Uncontaminated groundwater infiltration.
• Uncontaminated pumped groundwater.
• Discharges from uncontaminated potable water sources.
• Foundation or footing drains.
• Air conditioning condensation (commercial/residential only)
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• Irrigation waters
• Springs.
• Water from crawl space pumps.
• Individual residential car washing.
• Flows from riparian habitats and wetlands.
• Discharge of street wash waters.
• Firefighting activities.
• Discharges from dechlorinated swimming pools. These discharges do not include pool
filter backwash discharge or saltwater pool discharge, which are prohibited.
• Discharges associated with emergency removal and treatment activities for hazardous
materials if authorized by the federal, state or local government on -scene coordinator.
• Maintenance activities of the stormwater drainage system requiring flushing or cleaning
with potable water.
• Illicit discharge permitted under an NPDES permit, waiver, or waste discharge order
issued to the discharger and administered under the authority of the USEPA, or NCDWR,
provided that the discharger is in full compliance with all requirements of the permit,
waiver, or order and other applicable laws and regulations.
• Discharges specified in writing by the Town Manager as being necessary to protect
public health and safety or discharges that have been filtered through an approved
pretreatment system that consistently demonstrate no discharge of pollutants.
If any of the above -listed exceptions to the discharge prohibition are found to be polluted and
may therefore negatively impact the quality of the waters of the State, the discharge will be
considered an illicit discharge, as determined by the Town Manager.
3.2 WHAT IS AN MS4 AND STORM DRAINAGE SYSTEM?
A Municipal Separate Storm Sewer System (MS4) is the storm drainage and conveyance system within the
Town's corporate limits. The MS4 Stormwater Permit authorizes the Town to discharge stormwater from
the MS4 system to receiving waters ("Waters of the United States") in accordance with the limitations,
requirements, and conditions of the permit. One of the primary components (minimum measures)
included in the MS4 Stormwater Permit is to maintain and enforce a program to prevent and eliminate
illicit discharges into the MS4.
Municipal Separate Storm Sewer System (MS4): Pursuant to 40 CFR 122.26(b)(8), an MS4 means
a conveyance or system of conveyances (including roads with drainage systems, municipal streets,
catch basins, curbs, gutters, ditches, manmade channels, or storm drains):
Owned or operated by the United States, a State, city, town, county, district, association,
or other public body (created by or pursuant to State law) having jurisdiction over disposal
of sewage, industrial wastes, stormwater, or other wastes, including special districts
under State law such as a sewer district, flood control district or drainage district, or
similar entity, or an Indian tribe or an authorized Indian tribal organization, or a
designated and approved management agency under Section 208 of the Clean Water Act
(CWA) that discharges to waters of the United States or waters of the State.
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2. Designed or used for collecting or conveying stormwater;
3. Which is not a combined sewer; and
4. Which is not part of a Publicly Owned Treatment Works (POTW) as defined in 40 CFR
122.2.
Major Outfall: an outfall that discharges from a single pipe with an inside diameter of 36 inches
or more or its equivalent (discharge from a single conveyance other than circular pipe which is
associated with a drainage area of more than 50 acres); or for MS4s that receive storm water from
lands zoned for industrial activity (based on comprehensive zoning plans or the equivalent), an
outfall that discharges from a single pipe with an inside diameter of 12 inches or more or from its
equivalent (discharge from other than a circular pipe associated with a drainage area of 2 acres
or more).
Outfall: a point source where a MS4 discharges to waters of the United States and does not include
open conveyances connecting two MS4s, or pipes, tunnels or other conveyances which connect
segments of the same stream or other waters of the United States and are used to convey waters
of the United States.
Storm drain: a drain built to carry away excess water in times of heavy rain.
Stormwater drainage system: In addition to obvious components of the stormwater drainage
system, such as Stormwater pipes, catch basins and other storm drain inlets, the drainage system
includes street gutters, ditches, swales or other man-made channels, natural channels (e.g.,
streams) and other waterbodies, and structural Stormwater Control Measures (like detention
ponds or bioretention areas) that drain to streams.
Waters of the United States: The regulations regarding Waters of the United States was codified
in 33 CFR Part 328 and was effective on June 22, 2020. The following definition for jurisdictional
water was contained in section 328.3.
(a) Jurisdictional waters. For purposes of the Clean Water Act, 33 U.S.C. 1251 et seq. and
its implementing regulations, subject to the exclusions in paragraph (b) of this section,
the term "waters of the United States" means:
(1) The territorial seas, and waters which are currently used, or were used in the
past, or may be susceptible to use in interstate or foreign commerce, including
waters which are subject to the ebb and flow of the tide;
(2) Tributaries;
(3) Lakes and ponds, and impoundments of jurisdictional waters; and
(4) Adjacent wetlands.
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3.3 CHARACTERISTICS OF ILLICIT DISCHARGES
Each illicit discharge has a unique frequency, composition, and mode of entry into the storm drainage
system. Below are some terms used to describe these characteristics.
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, without changing, stopping, or being
interrupted. These discharges are usually easier to detect, and typically produce the
greatest pollutant load. Examples include sanitary wastewater piping that is cross -
connected from a building or sanitary sewer line to the storm sewer, or an industrial
operational discharge that is not permitted.
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. Examples include swimming pool discharges or discharges
that enter the stormwater system through pipe connections.
Transitory discharges are usually short in duration, lasting only a short time and then
disappear. These discharges usually in response to a singular event and are extremely
hard to detect even with routine monitoring, but under the right conditions, can exert
severe water quality problems on downstream receiving waters. Examples include
materials that have been dumped into a storm drain or stream, a floor drain connected
to the storm sewer system, a spill, sewer break, or an accidental discharge.
Mode of Entry: Illicit discharges can be classified based on how they enter the storm drain
system. The mode of entry can be indirect or direct.
Indirect entry means that flows generated outside the storm drain system enter through
storm drain inlets or by infiltrating through joints in a pipe - e.g., infiltration from cracked
sanitary systems, spills collected by drain outlets, outdoor washing activities that create
flow to a storm drain, or paint or used oil dumped directly into a storm drain.
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 —e.g., sewage cross -connections,
straight pipes, industrial and commercial cross -connections that are piped to the
stormwater drainage system. Direct entry usually produces discharges that are
continuous or intermittent.
See also the Common Pollution Problems section below.
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3.4 TOOLS FOR IDENTIFYING ILLICIT DISCHARGES
The Town maintains a comprehensive storm drainage system database in GIS that includes the drainage
network, as well as receiving waters and potential pollution generating sites. Outfall screening can be
useful for systematically looking for illicit discharges during dry weather conditions.
Generating Sites: Land use can help predict the potential for illicit 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. The density of generating sites within a subwatershed may be a good indicator of the
severity of local illicit discharge problems. Examples of generating sites within the Town's
corporate limits can be grouped into the following broad land use categories: Residential
Commercial, Industrial, Institutional, and Municipal Generating Sites.
Geographic Information Systems (GIS): a system designed to store, manipulate, analyze and
manage geographical data. The Town uses GIS to map the MS4, identify major outfalls and
receiving waters, trace illicit discharges to their source, and analyze the MS4 for generating sites
to better target education, monitoring and enforcement efforts. For more information, see Storm
Sewer System Mapping below.
Outfall Reconnaissance Inventory (ORI): a field screening method outlined by the Center for the
Watershed Protection (CWP), designed to quickly inventory storm sewer outfalls and identify
possible illicit discharges. The results of an ORI is to help focus resources on problem outfalls
requiring more intensive investigation.
During the ORI, major outfalls are assessed for discharges with qualitative parameters such as
color, odor, foam, debris, or other characteristics associated with potentially contaminated water.
Additionally, physical characteristics of the outfall are noted, such as the extent of submergence
if the outfall is partially underwater, the presence of head cuts, adjacent erosion of bed or bank,
and damage to the outfall itself. For more information, see Appendix A — Dry Weather Screening
SOP.
4 REGULATORY AUTHORITY
The Chapel Hill Town Council adopted an Illicit Discharge Detection and Elimination (IDDE) Ordinance
(Chapter 23, Article V of the Town Code of Ordinances) on November 14, 2016, that effectively prohibits
discharge of non-stormwater to the Town's storm sewer network. The IDDE Ordinance details the Town's
authority, spill response notification requirements, violation and enforcement procedures, and a schedule
of associated civil penalties and other remedies for violations of the ordinance. The IDDE Ordinance also
provides criteria for assessing civil penalties (see Criteria to Determine Amount of Penalties below).
The purpose of the ordinance is to:
• regulate the contribution of pollutants to the stormwater drainage system,
• prohibit illicit discharges and connections to the stormwater drainage system,
• prevent improper disposal of materials that degrade water quality, and
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• establish legal authority to carry out all inspection, detection, monitoring procedures and
enforcement necessary to ensure compliance with the ordinance.
Prior to the adoption of the IDDE Ordinance, the Town's authority for IDDE enforcement and penalties
was limited to Sections 8-34 and 8-44 of the Code of Ordinances.
5 STORM SEWER SYSTEM MAPPING
The Town's storm sewer system mapping includes a comprehensive collection of GIS datasets that are
used for IDDE investigations and prioritization (see Table 1). Completing and maintaining a storm sewer
system map that identifies major outfalls and receiving streams is a required component of the Town's
MS4 Stormwater Permit.
Table 1. Existing GIS Datasets for IDDE Investigations and Prioritization.
GIS Datasets for IDDE Investigations and Prioritization
(from Town of Chapel Hill, OWASA, UNC-CH, Carrboro, NCDEQ FEMA)
Town subwatershed boundaries
Receiving waters (streams and waterbodies)
Open channel conveyances (e.g., ditches and other open channels)
FEMA Floodplains
Stormwater pipes
Stormwater outfalls
Stormwater manholes/junction boxes
Stormwater catch basins/inlets
Stormwater Control Measures (SCMs) — private and municipally -owned
OWASA Sanitary Sewer System
OWASA Water System
NPDES-permitted Industrial Sites (per NCDEMLR)
UNC-CH and Carrboro stormwater infrastructure
Pollution Sources Geodatabase (known generating sites such as locations of commercial
dumpsters, landfills, underground storage tanks, septic systems, swimming pools, and
various businesses such restaurants, dry cleaners and automotive service stations)
Town Biological (Benthic) Monitoring Data (2011-present) — includes bioclassification and
habitat assessment data, as well as water quality parameter data collected during annual
monitoring
NCDEQ Biological Monitoring & Water Quality and Classification Data, including Impaired
Waters
Other data —topography (2' and 10' contours), impervious surfaces (buildings, roads,
sidewalks, driveways), current and historical aerial photos and orthophotos, parcels,
Town properties, OWASA easements, Town zoning and land use, neighborhoods,
greenways and trails, soils and geology, Town zoning and corporate limits (and other local
government boundaries)
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The Outfall Screening.mxd ArcGIS map document is used for outfall screening and IDDE investigations by
Stormwater Management staff and is located on the Stormwater Management Division's shared drive
here: S:\GIS_DATA\IDDE. All datasets listed above are included within the Outfall Screening map
document, with their source data mapped to the original location(s) where the data are stored. The
Stormwater Analyst ensures that this map document includes the most current data available on a regular
basis.
Maintenance of the Town's stormwater infrastructure data is based on the incorporation of as -built
surveys from new development projects, and field verification and systematic mapping of existing
infrastructure through on -going subwatershed studies. Field -verified data relies on a site visit and
inspection of existing storm sewer infrastructure, as well as discovery of previously unmapped storm
sewer structures.
6 PREVENTING ILLICIT DISCHARGES
The prevention of illicit discharges and connections identifies key behaviors of residents, generating sites,
and municipal operations that produce intermittent and transitory discharges. These key behaviors are
then targeted for improved pollution prevention practices that can prevent or reduce the risk of discharge,
such as public education and involvement, business education and outreach, and municipal pollution
prevention and good housekeeping.
6.1 PUBLIC EDUCATION AND INVOLVEMENT
This program involves:
• Promotion of a stormwater hotline for the reporting of water pollution and illicit discharges.
• Educational outreach events.
• Volunteer water quality monitoring, trash cleanups and storm drain marking.
• Outreach materials to target general illicit discharges from residential generating sites, including
auto care, lawn and garden care, trash and debris, erosion and sediment, and pet waste disposal.
This program is adaptable to target priority areas and discharges as they are located during field
inspections.
6.2 BUSINESS EDUCATION AND OUTREACH
This program involves targeting of outreach materials for different businesses, including:
• Restaurants
• Apartment Complexes / Multi -family communities
• Painting Businesses
• Mobile Car Washing
• Power Washing
• Landscaping Businesses
• General businesses and offices
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• Automotive Garages & Gas Stations
6.3 MUNICIPAL GOOD HOUSEKEEPING AND POLLUTION PREVENTION
This program involves:
• Annual training for all employees, including Stormwater 101 and site -specific training where
necessary.
• Evaluation of Town -owned buildings and facilities for possible illicit discharges.
For more information, refer to Town's SWMP for details about the Public Education and Outreach and
Public Involvement programs, Good Housekeeping and Pollution Prevention program, and the Town's
overall efforts to prevent illicit discharges. Information is also posted on the Town's Prevent Water
Pollution website.
7 COMMON POLLUTION PROBLEMS
7.1 SEDIMENT DISCHARGE
Sediment is the number one illicit discharge type within the Town. Sediment should stay contained within
a construction site and should not be on the streets where it can enter the storm drain. Sediment
problems are most likely to occur during or after rain, but may also occur if proper erosion controls are
not in place, storm drains are not protected, there is lack of a proper construction entrance, a site is being
dewatered, or if equipment is being washed down. Note that the source may be a regulated or un-
regulated construction activity under the Town's erosion and sediment control ordinance or other
approved Town permit. See Figures 1 & 2.
Where to look: Streams, streets, storm drains.
What to look for: Brown/orange, turbid water, usually with no unusual odor. Sediment/mud.
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Figure 1. Sediment discharge examples.
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�E
� M
Low Severity Sediment Moderate/Severe Severity Severe Severity Sediment Discharge
Discharge (Slightly Turbid Sediment Discharge (Turbid Water (Very Turbid Water with Heavy
Water) with Sediment Load) Sediment Load)
Source: Town of Chapel Hill.
Figure 2. Typical sediment discharge sources.
n
Unprotected storm drain inlet
Sediment pile on the street
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Source: CWP 2014 & Town of Chapel Hill.
7.2 WASTE MANAGEMENT
Trash and dumping areas are often found in commercial and residential areas. Trash and dumping can
wash into storm drains and streams, signal to others that it is acceptable to dump in the area, and can
pose a public health risk. Improper dumpster and grease container management can also result in
pollution that can wash into the storm drains and streams, and is a common source of illicit discharges in
Town, especially in areas where restaurants and other businesses may share common waste management
facilities (Figure 3).
Where to look: Behind restaurants, shared waste/recycling facilities. Areas that people do not
frequent such as behind buildings, and vacant lots.
What to look for: Poorly managed grease containers and dumpsters, trash on or in storm drains,
tires, food and drink containers, etc.
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Figure 3. Trash/dumping examples.
MASIF
INpVtIllF{
Low Severity Waste Management —
Moderate Severity Waste Management —
open dumpster with visible staining
poorly managed dumpster and/or dumping
0
+l
High Severity Waste Management — container lids
High Severity Waste Management — grease
open, and pile of cooking oil containers without lids
container open, spills and stains on the ground
s
j
40
High Severity Waste Management - Dumpster
High Severity Waste Management - Food waste, grease
"juice" draining from a trash compactor
and trash being dumped down a storm drain
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Source: CWP 2014 & Town of Chapel Hill.
7.3 YARD WASTE
Town of Chapel Hill IDDE Plan
NPDES Permit NCS000414
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Yard waste is usually piles of leaves, mulch, branches, or other residential waste (Figure 4). Yard waste is
exposed to rain and weather and can wash away to damage the environment. These piles of yard waste
are often found in piles in the street, behind homes near streams, in riparian buffers and in ditches. Yard
waste can clog storm drain systems and choke streams. Yard waste can also additional nutrients to
streams.
Where to look: Streets and sidewalks near homes. Ditches and streams near homes.
What to look for: Piles of leaves, mulch, grass clippings, trees, sediment, trash, etc.
Figure 4. Yard waste examples.
cr
Low Severity Yard Waste Moderate Severity Yard High Severity Yard Waste
Management — Leaves Waste Management — Management — Pile of mulch
accumulating in street gutter Clogged storm drain in street next to storm drain
Source: CWP 2014.
7.4 HAZARDOUS WASTE
Hazardous waste is waste that is dangerous or potentially harmful to our health or the environment.
Hazardous wastes can be liquids, solids, gases, or sludge. They can be discarded commercial products, like
cleaning fluids, paints, or pesticides, or the by-products of manufacturing processes (Figure 5).
Where to look: Automobile garages, gas stations, construction sites, and other commercial or
residential businesses. Also homes being renovated.
What to look for: Paint, oil, automobile parts, gas, construction material, chemical containers.
Chemical/solvent odor. White milky colored water in streams from paint washing or dumping;
oily sheen in streams from petroleum products (e.g. oil, gasoline).
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Figure 5. Hazardous waste examples.
er
jp
..AAKY
Low Severity Hazardous Waste — closed used oil
Moderate Severity Hazardous Waste — Batteries
container under partial cover
outside without cover, on pallets
High Severity Hazardous Waste — uncovered,
High Severity Hazardous Waste — Paint discharge from
unlabeled leaking barrels
dumping or washing into inlet
414'
High Severity Hazardous Wate - gasoline spill that
High Severity Hazardous Waste - Antifreeze entering a
entered a stormdrain then a stream (being
storm drain
contained with a boom)
Sources: CWP 2014 & Town of Chapel Hill.
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7.5 OUTDOOR WASHING ACTIVITIES
Outdoor washing may or may not be problematic. For example, hosing off a sidewalk or driveway or
individual residential car washing may not generate significant flows or pollutant loads. These examples
are not problematic unless done on an ongoing or chronic basis close to a waterway or storm drain.
However, washing fueling areas and power washing construction equipment in parking lots can generate
significant flows or pollutant loads and are therefore problematic. Residential homeowner car washing
and lawn watering are generally exempt ("allowable") activities, unless deemed to be significant
contributors of pollutants to the MS4. Outdoor washing of restaurant equipment and commercial vehicle
washing without proper containment of wash water is not acceptable. Some examples are shown in Figure
6.
Where to look: Car washes, car dealerships and rental companies, restaurants, fire stations, fleet
maintenance areas, parking lots with mobile car washes.
What to look for: Suds; sweet, fruity, detergent, or chlorine smells.
Figure 6. Outdoor washing examples.
Low Severity — power washing Low/Moderate Severity — covered Moderate/Severe Severity — outdoor
sidewalk without soap car wash at rental car agency, with washing of restaurant equipment with
soapy water draining toward inlet de -greasing cleaners
Source: Town of Chapel Hill.
7.6 WATER MAIN BREAKS & WATERLINE FLUSHING
Potable water leaking into the storm drain system is generally not considered to be an illicit discharge.
However, water main breaks (Figure 7) can damage infrastructure, waste treated drinking water supplies,
and threaten public safety and harm streams if breaks generate excessively high flows. Water main issues
may also be detected by the chlorine scent; if a strong chlorine scent is detected, this should be reported.
Waterline flushing can also release chlorinated water into storm drains and streams and cause erosion
and localized fish kills if not dechlorinated properly before release.
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Where to look: Streets, sidewalks, parking lots.
What to look for: Clear or muddy water seeping or spewing out of pavement. Very turbid water,
sediment, and/or localized fish kills in area streams.
Figure 7. Waterline break examples.
7.7 SANITARY SEWER & SEPTIC SYSTEM DISCHARGES
Sanitary sewage can enter the storm drain and streams through cracks in pipes, an illicit connection,
sanitary sewer overflows from clogs or broken clean out pipes, failed septic systems and/or straight pipes.
Field crews may see any of these sources of discharges during routine activities. Some examples are shown
in Figure 8.
Where to look: In storm drains, near sewer manholes, in streams, exposed sewer pipes.
What to look for: Sewage smells, gray or "scummy" water, toilet paper, scum in or below pipes.
Figure B. Sanitary sewage discharge sources.
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i
s
4 ks t
Sewage entering open channel Sewage overflow from clogged or broken Sewer lateral broken in a
from foundation drain line due cleanout pipe stream
to break in crawlspace
Source: CWP 2014 & Town of Chapel Hill.
7.8 POOL DISCHARGES
Chlorinated pool water being drained to a street, storm drain, or stream is considered an illicit discharge,
while dechlorinated discharges generally are not. Pool maintenance activities can also cause illicit
discharges when plaster or other materials are drained to the stormwater drainage system or improperly
disposed of (see Figure 9). Saltwater pool discharge is specifically prohibited, as is pool backwash.
Where to look: Storm drain pipes, streets, streams, driveways, yards.
What to look for: Clear water with chlorine odor, downstream fish kills.
Figure 9. Pool discharge examples.
Pool discharge from
outdoor pool at
apartment complex
r
Plaster slurry from pool
maintenance at apartment
complex poured down a
storm drain
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8 REPORTING AN ILLICIT DISCHARGE OR WATER QUALITY ISSUE
The Town of Chapel Hill is organized to receive reports of illicit discharges or other water quality and
drainage issues in a variety of ways to provide flexibility for residents to report potential violations and to
ensure that investigative staff can receive the complaints in a timely manner.
Below are the primary ways to report an illicit discharge or water quality issue. Procedures for reporting
illicit discharges and spills are included in the IDDE ordinance, and are also available on the Town's
Stormwater Management website.
8.1 HOW TO REPORT AN ILLICIT DISCHARGE OR CONNECTION
8.1.1 Hotline
The Town of Chapel Hill Stormwater Management Division main office hotline is (919) 969-RAIN (7246);
the voicemail for this hotline indicates that the caller should call 911 after hours to report an emergency.
This hotline is used to report potential illicit discharges, as well as flooding and drainage assistance,
stormwater billing questions, and other general inquiries.
The hotline number is published on the Stormwater Management Division website and advertised and
promoted on educational materials and during educational events.
8.1.2 Email
The Town of Chapel Hill Stormwater Management Division maintains the following email address to
report an illicit discharge or water quality concern: [e-mail].
8.1.3 SeeClickFix
Residents may also report illicit discharges through the SeeClickFix application, called Chapel Hill Connect,
from your smartphone, tablet, or computer. However, this application is intended to report non -
emergency issues, such as a blocked storm drain, park maintenance, or a pothole.
The exact location of the issue can either be automatically pulled in using GPS or adjusted manually. There
is an option to upload a photo with each service request, as well as the ability to comment on and follow
issues. Once submitted, the report will be directly routed to the appropriate department within the Town
and you will be notified when action is taken.
8.1.4 Town of Chapel Hill Report a Violation Website
The Town maintains a website to report a violation, including illicit discharges and erosion or drainage
issues, that is monitored by Code Enforcement staff in the Building and Development Services Division.
8.2 WHAT TO REPORT
The following minimum information should be included in a report of an illicit discharge:
• Location of problem
• Time and date problem was found
• Any observations such as odor, color, turbidity and floatables
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• One or more digital photos to document the condition, if possible
• Any other relevant or pertinent information
8.3 REPORTING MAJOR SPILLS TO STATE REGULATORS
Staff should report major spills and discharges to the North Carolina Department of Environmental Quality
(NCDEQ) Raleigh Regional Office (RRO) if they might be toxic, or if they involve a sufficient volume of
sewage, oil/gasoline, or other hazardous substances. Major fish kills may also be reported.
These reports are to be made within 24 hours of a spill/discharge verbally by contacting staff at the
NCDEQ RRO by phone at [phone]. If reporting outside normal business hours, call the NC Division
of Emergency Management at [phone] or [phone]. Voice mail messages or faxed
information shall not be considered as the initial verbal report.
When calling the RRO, document the time and date of the call and the person you spoke with, and be
prepared to give a statement including:
• The location of the spill,
• The time and date of the spill,
• A description of the incident causing the spill,
• The type of substance spilled,
• The approximate volume of the spill,
• The responsible parties (if known), and
• Any containment or remedial actions done or underway.
If reporting major spills to state regulators, please be sure to copy or otherwise inform Stormwater
Management staff.
Below is more detailed information for the reporting of particular types of discharges. The most
current information for reporting is found on the NCDEQ Emergency Response website.
8.3.1 Sanitary Sewer Collection System Overflows (SSOs)
Staff shall verbally report to a NCDEQ staff member at the RRO, but in no case more than 24 hours
following the occurrence or first knowledge of the occurrence of either of the following:
Any sewer system overflow and/or spill over 1,000 gallons; or
Any sewer system overflow and/or spill, regardless of volume, that reaches surface water.
8.3.2 Oil Spills
Oil spills that reach surface water must be reported to both NCDEQ and the National Response Center.
For oil spills that don't reach surface water, reference the list of Reportable Quantities of Hazardous
Substances: https://www.epa.gov/epera/consolidated-list-lists-under-eperacerclacaa-ss112r-august-
2020-version.
• For North Carolina, report oil spills Monday -Friday 8 a.m.-5 p.m. to the NCDEQ RRO. If no
answer, call [phone].
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• To report oil spills to the National Response Center, call [phone] (24 hours/day).
• To report oil spills after hours or on weekends in North Carolina, call [phone].
8.3.3 Hazardous Substance Spills
For spills of hazardous substances, determine if the spill is a reportable quantity or not by referencing a
list of Reportable Quantities of Hazardous Substances (https://www.epa.gov/epera/consolidated-list-
lists-under-eperacerclacaa-ss112r-august-2020-version).
Refer to "CERCLA RQ' column. Data is in pounds. If the spill meets or exceeds the reportable quantity,
report to North Carolina and the National Response Center the same way as reporting an oil spill.
8.3.4 Fish Kills
To report a fish kill, call the NCDEQ RRO (see contact info above).
9 FINDING ILLICIT DISCHARGES
Many illicit discharge investigations are initiated internally by Stormwater staff or other municipal
employees through direct observations while out in the community during daily work activities. Typically,
these investigations stem from three major sources and are discussed below: staff field observations,
routine water quality monitoring/stream sampling, and dry weather outfall screening.
9.1.1 Staff Field Observations
Stormwater staff members and other municipal employees who are often outdoors conducting fieldwork
or driving to locations throughout the Town may report a potential illicit discharge for investigation. Staff
members should use this time to be on the lookout for IDDE Ordinance violations. In general, the most
common and easy -to -spot issues are sediment discharges, discharges from outdoor washing activities,
sewage discharges, or commercial businesses with poor housekeeping (especially restaurants or areas
with community waste management areas). Discolored stream water and unusual overland water flows
or dry weather flows in stormwater catch basins are also common observations that should trigger an
investigation.
Stormwater staff regularly conduct stream determinations and examine outfalls during those site visits —
if an illicit discharge is suspected, an investigation is initiated. Because conducting stream determinations
requires that a site visit not take place within 48 hours of a rainfall event, discharge from outfalls during
dry weather is more noticeable. In addition, while systematically mapping the Town's storm sewer
infrastructure, any water quality issues observed at outfalls is documented in the Town's stormwater
infrastructure GIS database for follow-up investigation.
9.1.2 Water Quality Monitoring
The Town of Chapel Hill has a water quality monitoring program that evaluates the chemical, physical,
and biological characteristics of local streams annually. The purposes of this program include evaluation
of problem areas and identification of possible illicit discharges, as well as documenting water quality
trends over time in all subwatersheds. In obvious cases, investigations may be initiated by visual
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observation (e.g., dry weather flow, color and odor) at the time of sample collection. Data generated from
in -situ measurements are used to trigger water quality investigations when elevated pollutant levels,
indicative of an illicit discharge, are observed. These trigger levels will be used to initiate an investigation
at a specific monitoring location and should be followed upstream for potential pollution sources.
Indicator parameters and associated trigger levels from in -situ measurements (temperature, pH, dissolved
oxygen, specific conductivity) are located in Appendix A — Dry Weather Screening SOP.
9.1.3 Dry Weather Outfall Screening
A dry weather outfall screening program is a requirement in the Town's MS4 Stormwater Permit. The
Town's dry weather outfall screening program was developed to systematically screen outfalls using an
Outfall Reconnaissance Inventory (ORI) for pollutant indicators during dry weather to identify outfalls that
have suspect or obvious discharges. Dry weather screening can discover discharges from outfalls with
high turbidity, strong odors or colors, or that exceed expected water quality parameter (indicator) values.
Generating sites can be used to target high priority areas for screening.
See Appendix A: Dry Weather Screening Standard Operating Procedures (SOP) for details on how dry
weather screening is conducted and what pollutant indicators may be observed in the field.
10 ISOLATING & FIXING ILLICIT DISCHARGES
The Town uses a variety of tools to find and fix illicit discharge problems, including a pollution reporting
hotline, educating the public and Town staff, using GIS to identify generating sites with higher potential
for illicit discharges, conducting water quality monitoring and on -site investigations, and working with
responsible parties and coordinating agencies on correcting illicit discharges and engaging in necessary
enforcement actions.
10.1 DESKTOP ASSESSMENT OF ILLICIT DISCHARGE POTENTIAL
Illicit discharges are not uniformly distributed across a community but tend to be clustered within certain
land uses and subwatersheds, as well as in areas with aging infrastructure. This program component helps
narrow the search for the most severe problems, through analysis of existing mapping and water quality
monitoring data. Identifying which subwatersheds or generating land uses merit priority investigation
helps target areas of the MS4 that need more educational outreach and proactive outfall screening.
This method can also help more quickly respond to illicit discharge issues by allowing for quick generation
of field maps for investigations, as well as help identify gaps in data and other information needed to
include in the Town's mapping and prioritization efforts.
The Town utilizes comprehensive GIS databases that include data on subwatersheds, the stormwater
drainage network, including major outfalls and conveyance systems, receiving waters, water and sewer
infrastructure, and known or potential pollution generating sites. Stormwater staff use a shared GIS map
document that contains all GIS data needed to conduct desktop assessments and generate field maps for
investigations. See Storm Sewer Mapping above for more information, and Appendix A — Dry Weather
Screening SOP.
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10.2 TRACING AN ILLICIT DISCHARGE
Once an illicit discharge is detected, from reports from the public or Town staff, field work from water
quality monitoring or stream determinations, or from dry weather screening, the next step is to determine
the type of investigation needed to track down the source. Stormwater staff use investigations of the
storm drain network, on -site investigations, and drainage area investigations to determine the illicit
discharge source. Documentation with photos and other information, such as maps that show the path
of the discharge, is essential to include in the incident/investigation record.
10.2.1 Storm Drain Network Investigation
Storm drain network investigations narrow the source of the problem to a single segment of the storm
drainage system. The investigation starts at the outfall or at the source of the illicit discharge, and the
field crew decides how it will explore the upstream network to trace the discharge back up the
pipe/stormwater drainage network to isolate the specific source or improper connection, or traces it
downstream if the source is known so actions may be taken to eliminate it before it reaches surface
waters.
10.2.1.1 Working progressively up the network
Illicit discharges with unknown origins are traced by working up or down the storm sewer network
to narrow the source of the discharge - from the initial point of investigation, following visual,
physical and/or chemical indicators, through the network to the source. Moving up the network
when a discharge is detected at an outfall, Town staff use a storm sewer map and/or follow pipe
and drain connections. In places where the stormwater network splits or diverges into separate
subsystems, manholes can be examined moving upstream to determine which subsystem to
follow.
10.2.1.2 Working progressively down the network
When a discharge is observed draining to a storm drain inlet, it is followed down the storm sewer
network until the end of illicit discharge is found. This may involve accessing manholes and catch
basins before ending at an outfall, to ensure that the full extent of the discharge is identified (if
possible) and corrections are made to eliminate any discharge, especially before it reaches surface
waters.
10.2.2 Tools for tracing an illicit discharge
To identify an illicit discharge, or trace it through the stormwater conveyance system, investigators make
and document visual observations, and may also use water quality parameters using a meter to measure
temperature, specific conductivity, dissolved oxygen (DO), and pH. Staff have additional test kits for
ammonia and chlorine, and the Town has a contract with Pace Analytical when a water quality sample
may need to be analyzed in a laboratory. Dye testing or using clean water to identify flow paths may
also be utilized if the path of the network is not entirely known.
For more information on tracing an illicit discharge, see Appendix A — Dry Weather Screening SOP.
10.3 FIXING ILLICIT DISCHARGES
Once the illicit discharge is identified, steps are taken to eliminate the discharge. Staff work to identify
the responsible party, determine the best methods to use and how long it should take, and how removal
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will be confirmed. The Town typically uses an escalating enforcement approach, where voluntary
compliance and education is used for first-time, minor offenders. Many property owners may not even
be aware that a problem exists and are willing to fix the problem once educated. More serious violations
or continued non-compliance usually escalates to more aggressive enforcement actions. Refer to the
ENFORCEMENT section below for more information.
11 IDDE INCIDENT/INVESTIGATION TRACKING AND
DOCUMENTATION
This section of the IDDE Plan provides an overview of procedures for adequately tracking and
documenting illicit discharges in the IDDE Database and IDDE Incident Folders. The Town's IDDE Program
requires proper documentation to ensure procedures are followed and any illicit discharges identified are
properly recorded and responded to. Tracking and documentation also helps identify high priority
generating sites and chronic violators, supports enforcement efforts, and aids in the annual review of the
IDDE program.
The shared drive location for IDDE Database and associated Incident Folders is located here:
S:\SW_DATA\Compliance and Enforcement\Complaint_lnvestigation_Docs.
For information on tracking and documentation for dry weather outfall screening, see Appendix A — Dry
Weather Screening SOP.
11.1 IDDE TRACKING DATABASE
Illicit discharge complaints, investigations, and enforcement are tracked by Stormwater staff in an Excel
spreadsheet — the IDDE Database. Data recorded are shown in Table 2 below. Every field should be filled
out to the fullest extent possible for each complaint and investigation.
The Stormwater Specialist is responsible for maintaining the IDDE Database on a regular basis. The
Stormwater Analyst periodically reviews the tracking database for completion, and the tracking
information is used to generate annual reports, identify chronic violators, and evaluate program progress.
Table 2. IDDE Database field names and descriptions.
FIELD NAME
FIELD DESCRIPTION
PIN
Parcel Identification Number(s), if applicable
Street No
Street number
Street Name
Street name
Incident Date
Date of incident or report
Date Resolved
Date incident was resolved
Date Resolved Comments
Comments regarding incident resolution (e.g., "on -going")
NOV Issued? (Y/N)
Notice of Violation issues? (Yes or No)
Date/Time Reported
Date/time incident was reported in this YYYYMMDDHHMM
format (e.g., 201810150853 = October 15, 2018 at 8:53a.m.)
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FIELD NAME
FIELD DESCRIPTION
Date/Time Responded
Date/time incident was responded to (same format as above)
Town Staff
Town staff involved in response
Reported By
Who reported the incident (if known)
Discharge Type1
Primary illicit discharge type (from drop down menu)
Discharge Type2
Secondary illicit discharge type (from drop down menu)
IDDE Type Notes
Notes about the illicit discharge type
Contact - First Name
Name of contact/responsible party
Contact - Last Name
Title/Role
Title/role of contact/responsible party
Contact Phone Number
Phone number for contact/responsible party
Contact Email
Email address for contact/responsible party
Responsible Party - Company Name
Company name for contact/responsible party (if applicable)
Responsible Party - Address
Mailing address for contact/responsible party
Comments
Comments/notes about the incident
# of Offenses
Number of offenses involved in incident that require action
Materials Given
Name/type of educational materials provided
Other Agencies Contacted?
Names of any other agencies contacted or involved
File Folder Record? (Y/N)
File folder record? (Yes or No)
Link to Folder
Link to file folder on the Stormwater Management shared
drive
11.2 IDDE INCIDENT FOLDERS
Each entry in the IDDE Database corresponds to an Incident Folder on the Stormwater Management
shared drive. The Incident Folder contains all the details about the incident, including contact information
for the responsible party(ies), a timeline of actions, email correspondence, photos, notices of violation or
other enforcement actions, and other relevant documentation. Incident Folders follow this general
naming scheme: YYYYMMDD_[address or business name]_[IDDE type].
12 ENFORCEMENT
The Town's IDDE Ordinance outlines enforcement procedures and actions that may be taken because of
a violation. Enforcement action is undertaken by Stormwater Management staff acting as the Town
Manager's designee.
Upon a report or detection of a suspected illicit discharge or connection, staff investigate and gather
evidence, including photos. As described above, the IDDE Database is populated with information
pertinent to the investigation and enforcement actions taken, including 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, and is updated as the investigation progresses. All relevant documentation,
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including photos and correspondence, is saved in a corresponding Incident Folder. Documentation is key
to supporting enforcement actions.
12.1 (NOTICES OF VIOLATION
When the Town finds that there is a violation of the IDDE Ordinance, the party(ies) responsible are issued
a Notice of Violation (NOV) in writing by certified mail, personal service, or posting of the notice at the
facility where the violation occurred. Often, Town staff also issue the NOV via email (in addition to
certified mail) to expedite receipt more quickly. The NOV cites the Town's authority, describes the illicit
discharge, outlines remedies, specifies a timeline for compliance, and states potential or actual penalties.
Work by the responsible party to resolve/remediate the illicit discharge must follow a reasonable timeline
and is monitored with follow up investigations by Town staff to ensure compliance.
12.1.1 Eliminating the Source of an Illicit Discharge or Connection
Once the source of an illicit discharge has been identified, action steps are required to be taken to fix or
eliminate the discharge. The responsible party is identified (if possible), and education/compliance
assistance and/or enforcement actions are taken to address the discharge. An escalating enforcement
approach is usually undertaken, working toward voluntary compliance for first-time offenders. More
serious violations or continued non-compliance may warrant a more aggressive enforcement -oriented
approach.
The time frame allowed for repair or elimination of the discharge will be determined by the type of
repair/elimination needed and the difficulty in fixing the problem while immediately ceasing an active
illicit discharge.
12.1.2 Confirmation of Removal
Once a discharge or connection has been reported to be removed, field crews will confirm the removal.
Confirmation of removal will be performed through field documentation and photos, and may include dye
testing, and/or video testing for removal of illicit connections. Confirmation of removal must be
documented.
Refer to the Town's IDDE Ordinance for details on procedures associated with NOVs and other
enforcement actions.
12.2 CIVIL PENALTIES AND OTHER REMEDIES
The Town's Illicit Discharge Ordinance (Chapter 23, Article V, Section 23-89) provides the authority to issue
fines for illicit discharges and connections. Figure 10 below provides a summary of civil penalties that may
be assessed for first time and repeat offenders.
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Figure 10. Summary of civil penalties that may be assessed for first time and repeat offenders, per the Town's IDDE Ordinance.
Illicit Discharges
First time offenders:
or = 5 gallons: civil penalty not to exceed
$1000 per violation or per day for any
continuing violation
>5 gallons or contains non -domestic
substances or unknown volume/nature of
substance: civil penalty not to exceed 5000
per violation or per day for any continuing
violation
Repeat offenders:
Penalty amount doubles, not to exceed
$25000 per violation per day for any
continuing violation
Illicit Connections
First time offenders: Repeat offenders:
Civil penalty not to exceed $5000 per day of Civil penalty not to exceed $25000 per
continuing violation dav of continuing violation
other Violations
Civil penalty not to exceed $1000 per
violation or per day for any
continuing violation
12.2.1 Criteria to Determine Amount of Penalties
The following criteria are used to determine the amount of civil penalties assessed for illicit discharges
and connections that are found to be violations of the IDDE Ordinance. The Town Manager or his/her
designee shall use these criteria and document the justification of the assessed penalty.
a. The degree and extent of harm to the environment, the public health, and public and private
property;
b. The duration of the violation;
c. The effect on ground or surface water quality or on air quality or on flood hazard;
d. The cost of remedying the damage;
e. The amount of money saved by the violator through his, her, or its noncompliance;
f. Knowledge of the requirements by the violator, and/or reasonable opportunity or obligation to
obtain such knowledge;
g. Whether the violation was willful;
h. Whether the violation was corrected within the specified time period (the penalty shall be
assessed from the date of the violation and each day of continuing violation thereafter shall
constitute a separate violation under this article);
i. The prior record of the person responsible for the violation in complying or failing to comply with
this article; and
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j. The costs of enforcement to the town.
12.2.2 Procedure for Issuance of Civil Penalties
The following (internal) steps are taken by Stormwater staff once the Town Manager or his/her designee
determines a fine shall be issued for an illicit discharge or connection.
1. Stormwater staff drafts NOV and generates civil penalty amount using fine calculator (see criteria
above).
2. Stormwater staff sends draft NOV to Code Enforcement with brief description of violation and
amount of civil penalty assessed.
3. Code Enforcement officer enters the violation into LAMA and generates an Incident Number.
4. Code Enforcement officer creates Invoice and assigns an Invoice number.
5. Code Enforcement officer shares Incident Number and Invoice (with Invoice Number) with
Stormwater staff to include in Final NOV.
6. Stormwater staff issues NOV with Invoice, copying Code Enforcement officer and Revenue staff.
The charge code for stormwater enforcement payments is SWENF, linked to account 65010-48500.
12.2.3 Other Remedies
In addition to civil penalties, the Town's IDDE Ordinance specifies other remedies that may be pursued
for violations, including recovery of costs and fines, mandatory security for compliance, stop work orders
and withholding of inspections, permits, or certificates of occupancy, as well as judicial actions. Refer to
the IDDE Ordinance, Section 23-89, for more details.
12.3 APPEALS
The process for submitting an appeal for assessed civil penalties is detailed in the IDDE Ordinance, Section
23-90, as are enforcement measures that may be taken after appeal.
13 COORDINATING AGENCIES & CONTACT INFORMATION
Stormwater staff interact and coordinate with many other agencies related to the IDDE Program. Below
are summaries of some of these agencies that provide brief information on our mutual coordination. Table
3 provides contact information for individuals in each agency as well as the primary contacts for the IDDE
Program.
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Town of Chapel Hill IDDE Plan
NPDES Permit NCS000414
May 2021
Table 3. List of Contacts for Town Staff & Coordinating Agencies.
Name
Organization
Title
Phone Number
Email
Ernest Odei-Larbi
Town of Chapel Hill
Senior Engineer
[phone]
[e-mail]
Allison Weakley
Town of Chapel Hill
Stormwater Analyst
[phone]
[e-mail]
Jason Salat
Town of Chapel Hill
Stormwater Specialist
[phone]
[e-mail]
Gene Poveromo
Town of Chapel Hill
Code Enforcement
[phone]
[e-mail]
Coordinator
[phone] (C)
Emily Cochran
Town of Carrboro
Stormwater
[phone]
[e-mail]
Administrator
Janet Clarke
UNC-CH,
Stormwater Specialist
[phone]
[e-mail]
Environment, Health
[phone] (C)
and Safety
Victoria Hudson
Orange County
Environmental Health
[phone]
[e-mail]
Health Department
Director
[phone]
Jesse DuClau
OWASA
Manager, Distribution
[phone]
[e-mail]
& Collection Systems
Patrick Mallett
Orange County
Erosion Control and
[phone]
[e-mail]
Erosion Control
Stormwater Supervisor
Taylor Hartsfield
NCDEQ Raleigh
Regional Supervisor
[phone]
[e-mail]
Regional Office
General Office Phone
Number:
[phone]
13.1 CHAPEL HILL BUILDING AND DEVELOPMENT SERVICES
The Town of Chapel Hill Building and Development Services staff, which includes Code Enforcement,
partners with the Stormwater Management Division on sanitary sewer overflows, erosion control on
residential properties, illegal dumping, and other violations of the Town's Code of Ordinances.
For sanitary sewer overflows, the Stormwater Management Division may issue notices of violation with
plumbing or minimum housing code language included and Code enforcement staff copied when there is
a matter where the tenants do not have working water/sanitation. Code Enforcement staff are also legally
authorized to post stop work notices.
13.2 TOWN OF CARRBORO
The Town of Chapel Hill's Stormwater Management staff coordinate with the Town of Carrboro's
Stormwater program and staff regularly on projects of mutual interest. These projects include public
education and outreach, volunteer stream cleanup events, annual biological monitoring in the Bolin Creek
and Morgan Creek watersheds, stream restoration efforts in the Bolin Creek watershed, and stream
determinations for properties located in the vicinity of both jurisdictions. Town of Chapel Hill and
Carrboro stormwater staff also work closely on IDDE efforts across jurisdictions. In addition, the Town of
Chapel Hill and Town of Carrboro have an inter -local agreement to fund annual maintenance of a United
States Geologic Survey (USGS) stream gage on Bolin Creek at Village Drive.
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Town of Chapel Hill IDDE Plan
NPDES Permit NCS000414
May 2021
13.3 UNIVERSITY OF NORTH CAROLINA AT CHAPEL HILL - STORMWATER & ENERGY SERVICES
The Town of Chapel Hill's Stormwater Management staff communicate regularly with UNC Stormwater
Management and UNC Energy Services staff to discuss items of mutual interest, coordinate public
education and IDDE efforts, and co -review UNC development plans. A member of the UNC staff serves
on the Town's Stormwater Management Utility Advisory Board, and Town staff are involved in educational
and student research projects have been developed in collaboration with UNC's Institute for the
Environment, and courses taught through the UNC Department of City and Regional Planning. Town
Stormwater staff also serve as collaborators on stormwater and water quality grants obtained by UNC and
other academic partners.
The Town of Chapel Hill Stormwater Management Division staff and University of North Carolina at Chapel
Hill Stormwater staff report illicit discharge incidents when observed by staff in the other agency's
jurisdiction. This partnership helps to ensure that all observed illicit discharges are abated and remediated
properly.
13.4 ORANGE COUNTY ENVIRONMENTAL HEALTH
The Town of Chapel Hill Stormwater Management Division receives reports from Orange County
Environmental Health when Environmental Health staff observe illicit discharge violations during their
inspections of restaurants, grocery stores and other facilities. Some common examples of violations
reported include grease and sanitary sewer discharges. For example, there is an overlap of requirements
between the Town and the Orange County Environmental Health Department as it pertains to the
requirement of ceasing the use of all sanitary sewer fixtures until the repair of a sanitary sewer leak.
Orange County Environmental Health temporarily revokes the business license for the property until the
repair of a sanitary sewer leak is completed.
13.5 OWASA
The Town of Chapel Hill's Stormwater Management staff meet with OWASA engineering staff regularly
regarding development projects via the Town's Technical Review Team meetings and regarding Capital
Improvement Projects. The Town's staff also coordinate with OWASA Operations and Maintenance staff,
UNC Stormwater Management staff, and Town of Carrboro stormwater staff on water quality and illicit
discharge issues within our shared jurisdictions.
13.6 ORANGE COUNTY EROSION AND SEDIMENT CONTROL (E&SC ORDINANCE)
The Town's Soil Erosion and Sedimentation Control Ordinance (Chapter 5, Article V), was originally
adopted in 1986 to address soil erosion and sedimentation control and prevent degradation of area
waterways, and was last updated in 2001. This ordinance and its enforcement contribute to meeting the
Town's National Pollutant Discharge Elimination System (NPDES) minimum requirements for Construction
Site Stormwater Runoff Control, and it meets or exceeds state erosion control requirements.
For land development projects disturbing at least 20,000 square feet of land, an erosion and sediment
control permit is required. Single family development projects that that do not have to install stormwater
control measures on site or apply for erosion control permits but exceed 1,500 square feet of land
disturbance are still reviewed and approved by the Town of Chapel Hill to ensure that no sediment is being
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Town of Chapel Hill IDDE Plan
NPDES Permit NCS000414
May 2021
transported from the site or that drainage improvements have no adverse impact on neighboring
properties.
The Town's erosion control program is administered by the Orange County Erosion Control Division and
enforced by Orange County. Both the Town and the County are local delegated authorities to implement
and enforce state erosion and sediment control requirements and have had an inter -local agreement in
place since 1986.
Through an inter -local agreement, Orange County's Erosion Control Division administers, implements, and
enforces the Erosion and Sediment Control (E&SC) program for Chapel Hill, as well as other municipalities
within the county (Carrboro, Hillsborough). The Orange County Sediment and Erosion Control Program
effectively meets the maximum extent practicable standard for Construction Site Runoff Controls by
permitting and controlling development activities disturbing one or more acres of land surface and those
activities less than one acre that are part of a larger common plan of development. Town and Orange
County staff work together regularly on enforcement of the Town's erosion control requirements.
In 2021, the agreement between Orange County and the Town has been updated to reflect current MS4
permit requirements.
14 REFERENCES
Center for Watershed Protection (CWP) and Robert Pitt, Ph.D. 2004. Illicit Discharge Detection and
Elimination: A Guidance Manual for Program Development and Technical Assessments. EPA Cooperative
Agreement X-82907801-0. Washington, D.C.
CWP. December 2014. Shenandoah Valley MS4 Communities - Illicit Discharge Detection and
Elimination Field Guide: How to Identify and Quickly Report Pollution Problems.
Town of Chapel Hill. 2016. Illicit Discharge Ordinance, Town Code of Ordinances, Chapter 23, Article V.
15 APPENDIX A: DRY WEATHER SCREENING STANDARD OPERATING
PROCEDURES (SOP)
Page 36 of 36

APPENDIX A: Dry Weather Screening
Standard Operating Procedures (SOP)
1 INTRODUCTION............................................................................................................................................. 2
2 DRY WEATHER SCREENING PROCEDURES OVERVIEW....................................................................................2
3 BEFORE GOING TO THE FIELD........................................................................................................................3
3.1 WEATHER/CLIMATE CONDITIONS.........................................................................................................................3
3.2 SELECTING OUTFALLS FOR DRY WEATHER SCREENING..............................................................................................3
3.3 FIELD MAPS.....................................................................................................................................................4
3.4 FIELD EQUIPMENT.............................................................................................................................................4
4 IN THE FIELD..................................................................................................................................................5
4.1
COMPLETING THE ORI FIELD SHEET......................................................................................................................5
4.1.1
Section 1: Background Data.....................................................................................................................6
4.1.2
Section 2: Outfall Description...................................................................................................................6
4.1.3
Section 3: Quantitative Characterization for Flowing Outfalls................................................................7
4.1.4
Section 4: Physical Indicators for Flowing Outfalls Only..........................................................................8
4.1.5
Section 5: Physical Indicators for Both Flowing and Non -Flowing Outfalls............................................11
4.1.6
Section 6: Overall Outfall Characterization............................................................................................12
4.1.7
Section 7: Data Collection......................................................................................................................13
4.1.8
Section 8: Any Non -Illicit Discharge Concerns?......................................................................................14
4.1.9
Additional Visual and Audible Indicators...............................................................................................14
5 BACK IN THE OFFICE: DOCUMENTATION AND FOLLOWUP..........................................................................15
5.1
OUTFALL SCREENING PHOTOS...........................................................................................................................15
5.2
OUTFALL SCREENING DOCUMENTATION..............................................................................................................16
6 POLLUTANT
INDICATORS.............................................................................................................................16
6.1
AMMONIA (NITROGEN)....................................................................................................................................17
6.2
CHLORINE FREE & TOTAL)................................................................................................................................17
6.3
SPECIFIC CONDUCTIVITY...................................................................................................................................18
6.4
PH...............................................................................................................................................................18
6.5
DISSOLVED OXYGEN.........................................................................................................................................19
6.6
TEMPERATURE...............................................................................................................................................19
7 BIOLOGICAL INDICATORS............................................................................................................................ 20
8 REFERENCES................................................................................................................................................20
9 ATTACHMENT 1: ORI FIELD SHEET............................................................................................................... 20

Town of Chapel Hill IDDE Plan
Appendix A: Dry Weather Screening SOP
May 2021
1 INTRODUCTION
The Dry Weather Screening Standard Operating Procedures (SOP) are intended to be used by Stormwater
Management Division staff for inspecting stormwater outfalls (discharge points) as part of the Town's
Illicit Discharge and Elimination (IDDE) Program. This SOP contains procedures for screening outfalls for
dry weather flows and the presence of indicator pollutants to assess whether the dry weather flow is an
illicit discharge or connection. The procedures in this document are adapted from a combination of
guidance documents, field experience, and instructional manuals received with testing equipment.
This SOP shall be made available to all Stormwater Management staff and followed by those staff members
with principal responsibility for conducting outfall screening. New employees are expected to read and
become familiar with the manual before commencing dry weather screening and sampling. Periodically,
the manual will be updated to cover changes, such as the addition of new testing methods or identification
of priority areas.
Staff members are also expected to be familiar with information contained in the Town's IDDE Plan and
most current Stormwater Management Plan (SWMP). The SWMP includes a detailed summary of the
departmental responsibility for field activities, frequency of inspections, inspection procedures,
inspection equipment, and documentation procedures for field activities.
2 DRY WEATHER SCREENING PROCEDURES OVERVIEW
The dry weather outfall inspection and sampling procedures consist of the following general steps:
1. Check weather conditions to ensure there has been no than 0.1 inches of rainfall within the last
48 hours.
2. Identify outfall(s) to be screened/sampled based on the outfall inventory and priority ranking.
3. Acquire the necessary staff, mapping, and field equipment (see Table 2). If using the water quality
meter to measure water quality parameters, calibrate following the NCDEQ Physical and Chemical
Monitoring SOP, as modified by the Town for biological monitoring.
4. Conduct the outfall inspection during dry weather:
a. Mark and photograph the outfall.
b. Record the inspection information and outfall characteristics (using paper forms in
Attachment 1 or digital form using a tablet or similar device).
c. Look for and record visual/olfactory evidence of pollutants in flowing outfalls including odor,
color, turbidity, and floatable matter (suds, bubbles, excrement, toilet paper or sanitary
products). Also observe outfalls for deposits and stains, vegetation, and damage to outfall
structures.
d. If flow is observed, sample and test the flow following the procedures described below. If no
flow is observed, but evidence of illicit flow exists (illicit discharges are often intermittent or
transitory), revisit the outfall during dry weather within one week of the initial observation, if
practicable, to perform a second dry weather screening and sample any observed flow. Other
techniques can be used to detect intermittent or transitory flows including conducting
inspections during evenings or weekends and using optical brighteners.
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Town of Chapel Hill IDDE Plan
Appendix A: Dry Weather Screening SOP
May 2021
e. Input results from screening and sampling into the Outfall Screening Database. Include
pertinent information in the outfall/interconnection inventory and priority ranking.
f. File photos, field forms, and other relevant documentation on the shared drive.
3 BEFORE GOING TO THE FIELD
Before going to the field, weather conditions need to be reviewed to ensure there has been no more than
0.1 inches of rainfall within the previous 48 hours, field equipment needs to be collected, and maps need
to be made. Staff should be trained on basic methodology, be knowledgeable of the drainage area, and
be able to track discharges up the drainage system.
3.1 WEATHER/CLIMATE CONDITIONS
Dry weather outfall screening and sampling may occur when no more than 0.1 inches of rainfall has
occurred in the previous 48-hour period, and no significant snow or ice melt is occurring. Ideally, dry
weather screening should also consider high ground water tables.
For purposes of determining dry weather conditions, program staff will use precipitation data from the
sources listed in Table 1.
Table 1. Weather Stations in the Chapel Hill area.
Weather Station
Link
Horace Williams Airport
Chapel Hill, NC
https://climate.ncsu.edu/cronos/?station=CHAP&temporal=H
UNC Weather STEM
Chapel Hill, NC
https://orange-nc.weatherstem.com/unc
CoCoRaHS (Community Collaborative
Rain, Hail & Snow Network)
Triangle Metro Area, NC
https://www.cocorahs.org/Maps/ViewMap.aspx?state=usa
USGS Precipitation Gages
Chapel Hill, NC
Bolin Creek at Village Drive
https://waterdata.usgs.gov/nwis/uv?site no=355520079035845
Booker Creek at Piney Mountain Road (SR1751) -
https://waterdata.usgs.gov/nwis/uv?site no=355631079025645
3.2 SELECTING OUTFALLS FOR DRY WEATHER SCREENING
Outfalls included in dry weather screening shall be those that are 36 inches and larger or with a drainage
area of 50 acres or more within the Town's Municipal (Corporate) Limits. These outfalls will be identified
based on:
• Existing GIS storm sewer system mapping
• Ongoing storm sewer system mapping by consultants in select subwatersheds
• IDDE reports and subsequent field visits
• Stream determination field visits
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Town of Chapel Hill IDDE Plan
Appendix A: Dry Weather Screening SOP
May 2021
Due to limited resources, initial screening of outfalls will be prioritized based on areas with more complete
mapping and known problem areas (including areas with higher risk land uses and historical IDDE issues).
A more robust prioritization for outfalls to be screened will be developed per the Town's SWMP schedule
for implementation for IDDE BMPs.
Refer to the Desktop Assessment and Storm Sewer Mapping sections of the Town's IDDE Plan for GIS data
available for illicit discharge investigations and outfall screening. The Outfall Screening map document is
used to identify and prioritize outfalls, and is located here: S:\GIS_DATA\IDDE.
3.3 FIELD MAPS
Using the Outfall Screening map document, field maps should be created before going to the field, and
include at a minimum:
• labelled streets,
• hydrology (streams and waterbodies),
• stormwater infrastructure,
• parcel lines,
• OWASA sewer lines and manholes,
• contours, and
• other identifying landmark features (e.g., buildings, addresses, other impervious surfaces).
Field maps should delineate the contributing drainage area to major outfalls and can be created with and
without aerial imagery as the base map. Outfalls should be labelled on the field map with their Unique_ID
(in subwatersheds that have been systematically mapped), and that number is used in the ORI Field Sheet.
Maps should be created at a scale that is easy to read (e.g., 1:1200); more than one map may be needed
for an individual outfall if the drainage area is large. Ideally, maps should be created that delineate survey
reaches. If there are GIS data for known problem areas, add to the field map. Also check data for previous
visits to individual outfalls.
3.4 FIELD EQUIPMENT
Table 2 lists field equipment commonly used for dry weather outfall screening and sampling and illicit
discharge investigations.
Table 2. Field Equipment for Dry Weather Outfall Screening and IDDE Investigations.
Field Equipment Use/Notes
Clipboard For organization of field sheets and writing surface
Pencils/Permanent Markers For filling out field sheet and labeling of samples
Field Sheets ORI Field Sheets for both dry weather inspection and dry weather
sampling should be available with extras
Digital Camera For documenting field conditions at time of inspection
Cell Phone/Stopwatch/GPS For communication, a stopwatch for recording flow measurements, and
GPS location
Flashlight/headlamp w/batteries For looking in outfalls or manholes
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Town of Chapel Hill IDDE Plan
Appendix A: Dry Weather Screening SOP
May 2021
Field Equipment
Machete/clippers
For access through overgrown vegetation
Tape measure
For measuring distances and depth of flow
Nitrile gloves
Hand sanitizer
Personal Protective Equipment
(PPE)
Water Quality Meter
To protect the sampler as well as the sample from contamination
Disinfectant/decontaminant
Reflective vest, safety glasses and boots at a minimum
If needed, for sampling conductivity, temperature, pH, and dissolved
oxygen. Calibrate meter before leaving for the field.
Test Kits
If needed, for sampling ammonia, chlorine, and other water quality
parameters. Have extra kits on hand to sample more outfalls than are
anticipated to be screened in a single day
To measure flow
For sampling turbidity, if needed
For labeling sample containers
Make sure all sample containers are clean.
Keep extra sample containers on hand at all times.
Make sure there are proper sample containers for what is being sampled
for (i.e., bacteria requires sterile containers).
For transporting samples to a laboratory
Wide -mouth containers
Turbidimeter
Label Tape
Sample Containers
Cooler with ice
Chain of Custody Forms
To ensure proper handling of all laboratory samples
Safety Cones
Road and other hazard safety
Rubber Boots/Waders
For accessing shallow streams/areas
Sampling Pole/Dipper/Sampling
Cage
Manhole hook or magnet
For accessing hard to reach outfalls and manholes
Tool for lifting stormwater manhole covers
Spray paint
For marking outfalls that have been inventoried
First aid kit
For minor cuts or other injuries
4 IN THE FIELD
4.1 COMPLETING THE ORI FIELD SHEET
The Outfall Reconnaissance Inventory (ORI) Field Sheet (Attachment 1) is used during outfall screening to
record descriptive and quantitative information about each outfall inventoried in the field. For illicit
discharge investigations, refer to the IDDE Plan.
Below are summaries of the ORI field sheet sections. For more specific guidance on completing each
section of the ORI Field Sheet, and pictures that provide examples, refer to the CWP Manual (2004),
beginning on Page 98. This document also provides guidance on completing the field sheet.
Page 5 of 20

Town of Chapel Hill IDDE Plan
Appendix A: Dry Weather Screening SOP
May 2021
4.1.1 Section 1: Background Data
This section includes information about the location of the outfall, time and date of the inspection,
surrounding land use, and other relevant contextual information (Figure 1). This section of the ORI Field
Sheet may be partially completed before the inspection.
Figure 1. Background Data.
Section 1: Backsronud Data
Subwatershed
Outfall ID
Today s date_
Time [Military)-
Investigator.
Form completed by:
Temperature ff):
Rainfall (isL}. Last24 hours:
Last 48 hours:
Latitude Lanmtude-
GPS Unit GPS LIAK #_
Camera.
Photo *s:
Land Use to Drainaee Area (Check all that apply').
❑ Industrial
❑ ultra -Urban Residential
❑ Suburban Residential
❑ Commercial
❑ Open Space
❑ Institutional
Other.
Known Industries-
Notes (e.g_ origin of outfalL ifknonvn?.
4.1.2 Section 2: Outfall Description
This section of the ORI Field Sheet records information about the outfall itself, including the material,
shape, and dimensions of the pipe or open drainage channel (Figure 2). First, select whether the outfall is
a closed pipe or open drainage, fill in corresponding characteristics, and identify flow type (if any).
Figure 2. Outfall Description.
Section ?: Outfall Desci intion
LOCATION
MATERIAL
SHAPE
DIMENSIONS (IN.)
SUBMERGED
❑ RCP ❑ CMP
❑ C ucuiar
❑ Single
Diameter Drmensions
In Water:
❑ NO
❑ PVC ❑ HDPE
❑ Fhptical
❑ Double
❑ Partially
C] Fully
❑ Closed Pipe
El Steel
❑ Box
❑ Triple
With Sediment.
❑ Other:
❑ Other:
❑ Other _
❑ NO
❑ Partially
❑ Falb
❑ C oncrete
❑ Trapezoid
Depth.
❑ Eanhen
❑ Open draina_e
❑ Parabolic
Top Width:
❑ np-rP
❑ Other _
Bottom Width-
❑ Other:
❑ In -Stream
(applicable when collecting samples)
Flow Present".
❑ Ye-, ❑'tic IfNo, .5Lip ro.Semon5
Flow Desctip tion
(If ptesend
❑ Trickle ❑ Moderate ❑ SubstanhaL
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Town of Chapel Hill IDDE Plan
Appendix A: Dry Weather Screening SOP
May 2021
4.1.3 Section 3: Quantitative Characterization for Flowing Outfalls
This section of the ORI Field Sheet includes quantitative measurements for flow and water quality
parameters (Figure 3).
4.1.3.1 Measuring Flow Volume and Flow Rate
If collecting a sample from a flowing outfall, time how long it takes to fill the volume of the sample
collection bottle and record the time under Flow #1. This measurement can also be helpful if samples are
not being sent for analysis, to give a characterization of flow speed.
If the flow is of a measurable depth and width, record that information under Flow #2. Also record water
quality parameters as needed.
To measure the rate of flow at an outfall, use one of two techniques:
1. Measuring flow volume: Record the time it takes to fill a container of a known volume, such as a
one -liter sample bottle.
2. Measuring flow rate: Measure the velocity of flow, and multiply by the estimated cross -sectional
area of the flow.
4.1.3.1.1 Measuring Flow Volume
To use the flow volume technique, it may be necessary to use a "homemade" container to capture
flow, such as a cut out plastic milk container that is marked to show a one -liter volume. The shape
and flexibility of plastic containers allows crews to capture relatively flat and shallow flow. The flow
volume is determined as the volume of flow captured in the container per unit time.
4.1.3.1.2 Measuring Flow Rate
Measuring flow rate, based on velocity and cross -sectional area, is preferred for larger discharges
where containers are too small to effectively capture the flow.
Measure and mark off a fixed flow length (usually about five feet), crumble leaves or other light
material, and drop them into the discharge (crews can also carry peanuts or ping pong balls to use).
Then measure the time it takes the marker to travel across the length.
The velocity of flow is computed as the length of the flow path (in feet) divided by the travel time (in
seconds). Next, the cross -sectional flow area is measured by taking multiple readings of the depth and
width of flow. Lastly, cross -sectional area (in square feet) is multiplied by flow velocity (feet/second)
to calculate the flow rate (in cubic feet/second).
4.1.3.2 Water Quality Parameters
If taking water quality parameter measurements for temperature, pH, dissolved oxygen, specific
conductivity, follow the water quality meter instructions. If using test strips for chlorine and ammonia,
follow the procedures for test kits available.
When the water quality meter or test strips are used, measurements should be made from a sample bottle
that contains flow captured from the outfall. The exact measurement recorded by the field probe should
be recorded in Section 3 of the field sheet. Some interpolation may be required for test strips, but do not
interpolate further than the mid -range between two color points.
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Town of Chapel Hill IDDE Plan
Appendix A: Dry Weather Screening SOP
May 2021
Figure 3. Quantitative Characterization for Flowing Outfalls.
Section 3: Q> aliotathe Characterization
FIELD DATA FOR FLOWING OUTFALLS
PARAMETER RESULT UNIT EQUIPMENT
❑Flag =1
volme
LM
Settle
Time to fill
Sec
Flow depth
In
Tape me35tue
❑: =-
Fltm w7drh
Ft_ Ia
Tape meanae
ion
Measured leueth
Ft. IL
Iape measwe
Time of oriel
S
Stop uauh
TeMpEnrtue
°C
"Ieter
PH
PH Uoas
SIe e
ipec.fic C ooduc ::n"
µS ®
Meter
4.1.4 Section 4: Physical Indicators for Flowing Outfalls Only
This section of the ORI Field Sheet focuses on various physical indicators of illicit discharges for outfalls
with active flow at the time of the site visit. If there is no flow, skip to Section 5, below.
Figure 4. Physical Indicators for Flowing Outfalls Only.
Section 4: Physical Indicatot-s for Flooiug Outfalls Only
Ace Any Physical Indicators Present in the flaw' ❑ Yes ❑ No (If No, Skip to Sect- 5)
INDICATOR
CHECK if
DESCRIPTION
RELATIVE SEVERITY INDEX (1-3)
Present
'g ❑ Sewage ❑ Rancid-sosa ❑ Pebaleumas
❑ 3-M1onreabk from a
Odor
❑
❑ Sulfide ❑ Othet.
❑ 1-Faint
❑ _ -Eosdy detected
distance
Color
❑
❑ Clear ❑ Brown ❑ Gray ❑ Yellow
❑ 1- Faint colors in
❑ _' - Cleazly visibk m
❑ 3 - Clearly —ibk in
❑ Green ❑ Orange ❑ Red ❑Other
sampk bottle
sample bottle
ou"I flow
hgbldlt]'
❑
See Se —1)
❑ 1 - Slight C1-& R
❑ ' -Cloudy
❑ 3 -Opaque
Flwtabks
❑Sewage (Toilet Paper. etc J ❑Suds
❑ 1- Few: slight, origin
❑ 2- Some: iadi'mus
of angm (e.g.'
❑ 3 - Some: ongiu cku
(e.g.. obvious oil
-Does hot Irclude
Ttash!!
❑
El Petrokum (oil sheeu) ❑ Othec
not ob�io�s
p°s sib1, suds a oil
sheen. suds' or floe h-9
sheen)
sani�'matenals)
4.1.4.1 Odor
Odor can be effective in detecting certain types of illicit discharges. Section 4 asks for a description of any
odors that emanate from the outfall with flow and an associated severity score. Since noses have different
sensitivities, the entire field crew should reach consensus about whether an odor is present and how
severe it is.
• A severity score of one means that the odor is faint or the crew cannot agree on its presence or
origin.
• A score of two indicates a moderate odor within the pipe.
A score of three is assigned if the odor is so strong that the crew smells it a considerable distance
away from the outfall.
Fill a sample bottle at least halfway with sample water and hold about six inches away from your nose.
Use your free hand to fan the scent to your nose. Note: never inhale the air directly off the top of a sample
as many potential contaminants are harmful to nasal membranes and lung tissue. Make sure that the
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Town of Chapel Hill IDDE Plan
Appendix A: Dry Weather Screening SOP
May 2021
origin of the odor is at the outfall. Sometimes shrubs, trash, or even spray paint used to mark the outfalls
can confuse the nose.
Figure 5. Odor indicators of an illicit discharge, and common causes.
Odor
Common Causes
Rotten eggs/hydrogen sulfide
(septic)
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
Presence of raw or partially treated sewage, livestock waste
Gasoline, petroleum
Industrial discharge, illegal dumping of wastes, waste water
Sweet, fruity
Commercial wash water, wastewater
Odors may be produced from decaying organic matter. Under low oxygen or anaerobic conditions,
decaying matter can produce ammonia, hydrogen sulfide and methane. In some instances, the decaying
organic matter may be associated with accumulation of leaves in water.
A more common source of odor from organic decay is sewage. In addition to ammonia, hydrogen sulfide
and methane, bacterial decomposition of organic materials in sewage also results in production of thiols,
a class of compounds that are like alcohols except that sulfur takes the place of oxygen and have strong
odors.
Sewage odors may indicate an illicit discharge such as an sanitary sewer overflow, but sewage odors also
come from air escaping from sewer manholes. It is usually easy to determine when the odor is coming
from a sewer manhole by moving around the manhole, to determine that the odor is present downwind
but not upwind.
Stormwater manholes should not have sewer odors. Ideally manhole covers should properly identify
manholes as sanitary sewer or as stormwater. Some manholes have been found to have a lid that is not
labeled correctly. Incorrect labeling may be obvious when working in sewer easements, but in other
locations, the manhole labeling may not be reliable. Investigators can use GIS resources to confirm the
system for a manhole.
Once sewer manholes have been ruled out, sewage odors coming from a stream are strong indicators of
sewage contamination. A screening test for ammonia should be conducted to confirm.
Petroleum odor in a stormwater pipe may indicate an underground plume entering the pipe, a leaking
heating oil tank, a spill, etc. Gasoline odors in confined spaces such as pipes should be considered
hazardous. Move to a safe distance and contact your supervisor and the Town of Chapel Hill Fire
Department.
4.1.4.2 Color
Visual observation of color can be very effective at determining the source of illicit discharge at an outfall.
The color of the discharge as characterized in Section 4 of the ORI should be noted. The best way to
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measure color is to collect the discharge in a clear sample bottle and hold it up to the light. Look for
downstream plumes of color that appear to be associated with the outfall.
Table 3. Color indicators of an illicit discharge, and common causes.
Color
Common Causes
Tan to light brown
Suspended sediments common after rainfall. Runoff from construction, roads,
agricultural/range land; soil erosion caused by vegetation removal
Pea green, bright green,
Algae or plankton bloom - color depends on type of algae or plankton
yellow, brown, brown-
Sewage, fertilizer runoff, vehicle wash water
green, brown- yellow, blue-
green
Tea/coffee
Dissolved or decaying organic matter from soil or leaves. Commonly associated
with tree overhangs, woodlands, or swampy areas
Milky white
Paint, lime, milk, grease, concrete, swimming pool filter backwash or slurry from
pool maintenance
Milky or dirty dishwater gray
Gray water or wastewater, musty odor present
Milky gray -black
Raw sewage discharge or other oxygen -demanding waste (rotten egg or
hydrogen sulfide odor may be present)
Clear black
Turnover of oxygen -depleted waters or sulfuric acid spill
Dark red, purple, blue, black
Fabric dyes, inks from paper and cardboard manufacturers
Orange -red
Leachate from iron deposits, deposits on stream beds often associated with oil
well operations (check for petroleum odor)
White crusty deposits
Common in dry/arid areas or during periods of low rainfall where evaporation of
water leaves behind salt deposits. Also found in association with brine water
discharge from oil production areas (a petroleum odor or an oily sheen may be
present along banks)
4.1.4.3 Turbidity
The ORI asks for a visual estimate of the turbidity of the discharge, which is a measure of the cloudiness
of the water. Like color, turbidity is best observed in a clear sample bottle; it can also be quantitatively
measured using a turbidimeter. Look for turbidity in the plunge pool below the outfall and note any
downstream turbidity plumes that appear to be related to the outfall. Turbidity in the plunge pool may
be from localized erosion of the pool itself.
Field crews can sometimes confuse turbidity with color, which are related but are not the same. Turbidity
is a measure of how easily light can penetrate through the sample bottle, whereas color is defined by the
tint or intensity of the color observed.
4.1.4.4 Floatables
Look for any floatables in the plunge pool below the outfall. Sewage, oil sheen, and suds are all examples
of floatable indicators; trash and debris are generally not in the context of the ORL The presence of
floatable materials is determined visually (see Figure 6).
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Figure 5. Floatable indicators of an illicit discharge, and common causes.
Floatables
Common Causes
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, or 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 without reforming the original swirl
pattern, then it is natural.
If the floatable looks like sewage, assign it a severity score of three since no other source looks quite like
it. Surface oil sheens are ranked based on their thickness and coverage. In some cases, surface sheens
may not be related to oil discharges, but instead are created by in -stream processes.
A thick or swirling sheen associated with a petroleum -like odor may be diagnostic of an oil discharge.
Suds are rated based on their foaminess and staying power. A severity score of three is designated for
thick foam that travels many feet before breaking up. Suds that break up quickly may simply reflect water
turbulence and natural surfactants from decaying organic matter, and do not necessarily have an illicit
origin. A sheen from bacteria can form a sheet -like film that breaks if disturbed. On the other hand, suds
that are accompanied by a strong organic or sewage -like odor may indicate a sanitary sewer leak or
connection. If the suds have a fragrant odor, they may indicate the presence of laundry water or similar
wash waters.
4.1.5 Section 5: Physical Indicators for Both Flowing and Non -Flowing Outfalls
This section is used to record any outfall damage, deposits or stains, abnormal vegetation, poor pool
quality (odors, colors, etc.), or benthic growth in the pipe, such as algae (Figure 5). Make any additional
comments that may help determine whether or not illicit discharge is ongoing.
Figure 7. Physical Indicators for Both Flowing and Non -Flowing Outfalls.
S"tion 5: Physical Indicators for Both Flowing and Yon -Flowing Outfalls
Are ph�-sical indicators that are not related to fog- present? ❑ Yes [-]No UfNo, Skin to Section 6)
INDICATOR
CHECK if Present
DESCRIPTION
COMMENTS
Omfall Damage
❑
❑ Spallov. Grading m Chipping ❑ P-h- Paim
❑ Corrosive
Dep—m-Statns
❑
Q Oily ❑ Flaw I— ❑Faun ❑ Oflxr.
Abnoemal Vptation
❑
❑ Eace i- ❑ I hibiwd
Poor pool quality-
❑
❑ odors ❑ Colors ❑ Floatables ❑ Oil Sheen
Q suds ❑ Ext-swe Algae ❑ O'lter
Pipe benthic gruuth
❑
❑ 13— ❑ Dsange ❑ Cnren ❑ Ocher.
4.1.5.1 Outfall Damage/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
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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.
4.1.5.2 Deposits/Stains
Things to consider for deposits and stains associated with outfalls:
• 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
• 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
4.1.5.3 Abnormal Vegetation
Shallow backyard ditches may indicate an attempt to drain water from an illicit discharge. In some cases,
this may be done to drain laundry wastewater, a foundation drain or sump pump, or rising water from a
failed septic system absorption field. Vegetation that is much greener than nearby vegetation may
indicate a source of nutrients such as a discharge from a failing septic system or broken sewer line.
4.1.6 Section 6: Overall Outfall Characterization
The Center for Watershed Protection (CWP) developed outfall classifications to categorize outfalls based
on their characteristics and likelihood to pose a problem. Use these classifications to record the state of
the outfall at the time of inspection.
Classification:
1. Obvious
2. Suspect
3. Potential
4. Unlikely
Figure 8. Overall Outfall Characterization.
Section 6: Ot-erall Outfa➢ Charaeterizatian
❑ Culikehv ❑ Potential (presence of mo or more indicators) ❑ Suspect (oue or more mdicators i[ith a sere m of 3) ❑ Obvious
Do the physical indicators and overall appearance indicate that an illicit discharge may be occurring?
Make any necessary comments. If an outfall suspect or obvious, an illicit discharge investigation should
be initiated; if potential, more information may be needed before investigating.
Examples:
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1. Obvious: Flowing outfall where there is an illicit discharge that does not require sample
collection for confirmation; exhibits physical indicators and field -measured chemical
indicators.
2. Suspect: Flowing outfall with high severity on one or more physical indicators.
3. Potential: Flowing or non -flowing outfall with presence of two or more physical indicators
4. Unlikely: Non -flowing outfall with no physical indicators of an illicit discharge
4.1.7 Section 7: Data Collection
Samples for a laboratory should be collected for further analysis only if the illicit discharge source is
unknown after further investigation and sampling is necessary to determine the source.
If a sample is being collected for analysis, mark whether it was taken directly from the outfall or from a
pool below the outfall, and whether an intermittent flow trap was set (e.g., an optical brightener trap or
caulk dam) (Figure 9). Ultimately, this section should be used to recommend whether or not followup
sampling is needed. See below information on coordinating with a laboratory for sample analysis.
Figure 9. Data Collection.
Section ': Data Collectiou
1. Sample foi the lab:' ❑ Yes ❑ No
'_ If ves. collected from: ❑ Flow ❑ Pool
3. Iutemutteut flow trap set' ❑ Yes ❑ No If Yes. nape: ❑ OB11I ❑ Caulk dam
4.1.7.1 Samples Collected for a Laboratory
The Town currently has a contract with Pace Analytical: https://www.pacelabs.com/environmental-
sciences/testing-services.htm1.
Samples should be collected when testing for parameters included in the ORI field sheet or other
parameters designated by the Town (e.g., temperature, pH, specific conductivity, dissolved oxygen,
ammonia, chlorine) yields results above action levels for all parameters while indicators of an illicit
discharge are also observed (see Pollutant Indicators below).
If samples are collected for analysis, prepare them for shipment to the appropriate laboratory. Make sure
to fill in the Chain of Custody as appropriate.
If sewage is suspected to be present, the samples should be analyzed by the OWASA laboratory. Make
sure to complete the appropriate Chain of Custody form and store samples at the required temperature
(usually 2-4°C).
4.1.7.1.1 Procedures for Sample Collection
If flow is present during a dry weather outfall inspection, a sample will be collected and analyzed for
temperature, pH, and specific conductivity; if these parameters are within a normal range, and no other
pollutant indicators are present, the discharge may be due to groundwater intrusion.
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If an illicit discharge is suspected and the issue cannot be identified, collect additional parameters,
including dissolved oxygen and ammonia. The general procedure for collection of outfall samples is as
follows:
1. Fill out all sample information on sample bottles and field sheets
2. Put on protective gloves (nitrile/latex/other) before sampling
3. Collect sample with dipper or directly in sample containers. If possible, collect water from the
flow directly in the sample bottle. Be careful not to disturb sediments.
4. If using a dipper or other device, triple rinse the device with distilled water and then in water to
be sampled (not for bacteria sampling)
5. Use test strips, test kits, and field meters (rinse similar to dipper) for most parameters.
6. Place laboratory samples on ice for analysis of bacteria and pollutants of concern
7. Fill out chain -of -custody form for laboratory samples
8. Deliver samples to the laboratory
9. Dispose of used test strips and test kit ampules properly
10. Decontaminate all testing personnel and equipment
Field test kits or field instrumentation are permitted for all parameters except indicator bacteria and any
pollutants of concern. Field kits need to have appropriate detection limits and ranges.
4.1.8 Section 8: Any Non -Illicit Discharge Concerns?
List any additional concerns you may have about the outfall (Figure 10).
Examples include various groundwater flow observations. This could be specific reference to things such
as iron -oxidizing bacteria presence from groundwater flow causing an orange color/substance to be
present or a natural sheen often mistaken for automotive fluid. There can also be groundwater flow
without the indicators mentioned above possibly seeping into separations of pipe segments of the outfall
pipe or overland flow of groundwater entering a storm drain and exiting an outfall. Stormwater runoff
containing pollen can cause a strong yellow color and film to appear on water exiting outfalls, especially
in Spring months.
Figure 10. Any Non -Illicit Discharge Concerns?
5ectiou 8: my Non-1Wcit Dhcharge Concerns (e.g.. trash or needed infrastructure repairs)''
4.1.9 Additional Visual and Audible Indicators
4.1.9.1 Sound
Though not included in the ORI Field Sheet, the sound of running water can often be helpful in determining
things in the field such as the observation of or direction of flow and locating possibly buried stormwater
conveyance infrastructure. Running water may be due to groundwater entering a separated stormwater
pipe, or from groundwater flow underneath a pipe. Groundwater intrusion into stormwater pipes is
common within the Town.
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4.1.9.2 Black or gray 'floc"
A reliable visual indication of sewage contamination is fluffy black or gray "floc" that can usually be found
floating near the bottom of the water in areas where the water is stagnant or moving only slowly. The
water above the floc can be cloudy or even clear but the floc indicates that the water is likely to be highly
contaminated. Floc is likely to settle and collect in areas where the water is moving slowly or does not
appear to be moving at all.
4.1.9.3 Films and sheens
Oils and grease, including petroleum, are lighter than water. Petroleum products typically spread out on
the surface of water, forming a rainbow sheen. Rainbow sheens may indicate an illegal connection,
sewage, petroleum discharge from vehicle accidents, etc.
A blue film type of sheen may be formed as a by-product of iron bacteria. This type of sheen looks like
blue oil on the water. This blue film can be distinguished from oil by disturbing the surface of the film. If
the film breaks apart, it is from iron bacteria; if it quickly spreads to re-cover the water, it is oil.
In most cases, appearance is a good indicator of a possible problem. A notable and often dramatic
exception to this is caused by iron bacteria.
Iron -oxidizing bacteria are a group of microscopic, unicellular organisms that grow in chains and excrete
a mucilaginous material and appear as a fuzzy coating in water or on the surface of soil. The color is usually
orange -red to light brown. The presence of iron -oxidizing bacteria is a general indicator of groundwater
flow although there will not always be a visual presence of the bacteria. Groundwater flow can also
potentially explain innocuous flows during the dry weather screening process.
5 BACK IN THE OFFICE: DOCUMENTATION AND FOLLOWUP
5.1 OUTFALL SCREENING PHOTOS
Photos should show any discharge from the outfall, as well as the inside of the catch basin or interior of
stormwater drains connected to the stormwater drainage system that are contributing to a suspected or
confirmed illicit discharge discovered during dry weather outfall screenings. Include photos of the point
source (or the best approximation of a point source) that the illicit discharge is originating from and any
surface water the illicit discharge might be flowing into (e.g., upstream and downstream photos).
Photos of anything in the surrounding area that can provide context can be taken as well when applicable.
Examples include:
• Street names
• The exterior of commercial or residential buildings and/or their addresses if posted, and
• Nearby unaffected upstream portions of water bodies
For instances where no flow is observed, a non -illicit discharge flow is observed, outfall damage is
observed, etc., photos should be taken of only the screened outfall and additional photos should be
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limited to those that can provide context. If there are noticeable pipe separations upstream from the
outfall, those should be documented with photos and notes on the ORI Field Sheet.
5.2 OUTFALL SCREENING DOCUMENTATION
5.2.1.1 Saving Photos & Documentation
Photos and documentation for outfall screening should be stored on the Stormwater Management shared
drive located here: S:\SW_DATA\Compliance and Enforcement\01_OUTFALL SCREENING
Create a folder for the individual outfall sites should follow this naming convention: Outfall ID number.
Within each outfall site folder, a subfolder should be created with the date of the visit. A copy of the ORI
Field Sheet should be scanned and placed in the individual subfolder for the outfall, along with photos
and other documentation.
For instances when there is a confirmed or suspected illicit discharge that include multiple affected
outfalls, create a subfolder with a name that is the address of the responsible part(ies) for the illicit
discharge and create subfolders within for individual outfalls.
Photos and documentation for illicit discharge investigations should be filed here:
S:\SW_DATA\Compliance and Enforcement\Complaint_lnvestigation_Docs
Future options for filing documentation and photos will be considered as staff transition to field -based
technology using ArcGIS.
6 POLLUTANT INDICATORS
Figure 11. Pollutant indicator water quality parameters, potential sources, and level of concern.
Parameters
Potential Sources
Level of Concern
Ammonia -Nitrogen
Microbial decomposition of animal and plant
1.0 mg/L
proteins, sanitary wastewater, raw or partially
treated sewage, petroleum refining and chemical
industries, synthetic fibers and dyes, drugs,
pesticides, and fertilizers
Chlorine
Used to indicate inflow from potable water
1.0 mg/L
sources;
as disinfectant in water and wastewater
treatment processes
Specific Conductivity
Used to measure total dissolved solids (TDS); TDS
300 uS/cm+
can increase as a result of wastewater
discharges, irrigation, heavy metals, swimming
pool discharge, and overuse of fertilizers
Detergent
Can indicate a discharge from wash water or
0.2 mg/L
laundry
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pH
Extreme pH values (low or high) may indicate
commercial or industrial flows
Below 6.0 and above
9.0
Dissolved oxygen (DO)
4 mg/L or less
Temperature
32 degrees C or more
6.1 AMMONIA (NITROGEN)
Ammonia can convert to other forms of nitrogen. Consequently, ammonia is best used to screen flows
relatively near a source. Once water enters a stream, ammonia generally loses its utility as an indicator.
Domestic sewage contains between 40 and 70 mg/L of total nitrogen in several forms, most of which is
quickly converted to ammonia in the absence of oxygen. The residence time in septic tanks is long and
virtually all the nitrogen is converted to ammonia. Septic tank effluent may have up to 80 mg/L of
ammonia -nitrogen. Higher concentrations of ammonia may also be found in industrial effluents. Ammonia
is a major component of fertilizers.
Low-level ammonia nitrogen may be naturally present in water because of the biological decay of plant
and animal matter. During leaf fall in autumn, stagnant pools of water may fill with fresh leaves which
release ammonia as they decay. Flowing water in streams generally has sufficient oxygen and sufficient
time to convert ammonia to oxidized forms (NOx), but stagnant pools with decaying leaves may be
expected to have concentrations over 1 mg/L.
Excessive ammonia concentrations are toxic to aquatic life. When pH is greater than 9 and water is warm,
comparatively low concentrations of total ammonia can result in fish kills, particularly in combination with
other stressors ( i.e. elevated chlorine from potable water sources such as water line breaks). The Town
of Chapel Hill has established 1 mg/L ammonia- nitrogen as the threshold concentration for suspecting an
illicit discharge in dry weather flows from outfalls. This limit is consistent with Chapel Hill's extensive tree
canopy and potential for encountering leaf -produced ammonia.
6.2 CHLORINE (FREE & TOTAL)
Because of its strong oxidizing properties, chlorine in aqueous solution is an excellent biocide used to treat
potable waters, municipal wastes and swimming pools. Chlorine can also have an adverse effect on natural
surface waters due to its effect of killing beneficial bacteria as well as the caustic effect it has on aquatic life
(potentially death) by causing fish and amphibians to lose their protective natural slimy coating.
OWASA's treated water typically has between 0.8 and about 1.5 mg/L of chlorine, although the
concentration will vary throughout the water distribution system. During most of the year, OWASA uses
chloramines as the form of distribution system disinfectant. Measuring total chlorine will measure either
form.
Concentrations of chlorine over about 0.75 mg/L are strong indications of potable water discharge.
Chlorine must be measured at the time of sample collection; therefore laboratory confirmation is not
reliable. Measurements that range from 0.25 mg/L to 0.4 mg/L indicate a possible potable water source.
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(Lab measurements of fluoride have been used to confirm the source to be potable water. Fluoride
measurements greater than 0.4 mg/L can be used to give a confirmation).
6.3 SPECIFIC CONDUCTIVITY
Specific conductance or conductivity is a measure of the ability of water to conduct an electrical current.
It is highly dependent on the amount of dissolved solids in the water. Specific conductance is a
temperature corrected value and approximates what the actual conductance of a solution would be at 25
degrees Celsius. Specific conductivity provides an idea of the amount of dissolved material in the water, -
other pollutants can attach themselves to the surfaces of dissolved materials. Other measures of dissolved
solids are Total Dissolved Solid (TDS), which is determined in a laboratory, and salinity, which is used to
measure seawater concentration.
The conversion of conductivity to the total dissolved solids depends on the chemical composition of the
sample and can vary between 0.55 and 0.90. Specific conductivity is measured in microsiemens per
centimeter (Its/cm). Distilled water has a specific conductivity range of 0.5 to 3 Its/cm. The specific
conductivity of streams in Chapel Hill varies, but ranges in general between 80-250 Its/cm (based on
annual biological monitoring results). Lower values typically occur during wetter periods, which is usually
winter and spring in Chapel Hill.
Rainwater, being slightly acidic, tends to dissolve minerals as is it passes over the ground, increasing
conductivity. Groundwater generally has higher mineral content than surface water. Domestic
wastewater tends to have Total Dissolved Solids measurements that are 100 to 300 mg/L higher than the
source water.
Other sources of dissolved solids include fertilizer runoff, runoff from winter roadway anti -icing and
deicing operations conducted for public safety, and discharges from water softener recharging operations.
Specific conductivity may be useful for comparative measurements to identify likely source or to trace
sources quickly. If a pollution signature includes a strong conductivity signal, then comparative
measurements may be used to quickly trace upstream. Comparative measurements may be made
upstream and downstream of a suspected source.
6.4 PH
pH is a measure of how acidic or basic a substance is. When equal to 7.0, the pH is neutral. pH influences
the chemistry of many other substances. Under normal conditions it is rarely outside the range of 6 to 9
specified in North Carolina Water Quality Standards. However, pH outside this range can be very harmful
to aquatic life, and elevated pH in the range of 8.5 to 9 in combination with warm water significantly
increases the toxicity of ammonia.
The pH of rainwater at roughly 5.8 is acidic. Water passing over substances pick up mineral substances
that tend to buffer the water. River water is normally from 6 to 7. Wetlands and swamps will have lower
pHs. Water passing through decaying vegetation, including water high in tannins, will have low pH.
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6.5 DISSOLVED OXYGEN
Dissolved oxygen is measured in milligrams per liter (mg/L). Instruments that measure temperature as
well as dissolved oxygen can display "percent saturation." Milligrams per liter are the amount of oxygen
in a liter of water. Percent saturation is the amount of oxygen in a liter of water relative to the total
amount of oxygen water can hold at that temperature.
Temperature plays an important role influencing the amount of oxygen that water can hold at saturation.
Water at 31 degrees Celsius can hold about half as much dissolved oxygen as water at 1 degrees Celsius.
Algae and other plants in water produce oxygen during photosynthesis. Oxygen also enters water from
the atmosphere, although such transfer is typically very slow if the water is stagnant. Oxygen is consumed
by plants, bacteria, and other organisms during respiration. Like pH, high concentrations of algae can lead
to swings in dissolved oxygen. This is because at night, DO is consumed and CO2 produced, whereas during
the day, the algae are net producers of DO and consumers of CO2.
Plants both produce and consume oxygen, but production occurs only during daylight, while consumption
occurs at night. This daily or diurnal cycle occurs in streams and lakes. In hyper-eutrophic water bodies,
the large biomass of algae causes dissolved oxygen to undergo large swings, at times super -saturated and
at other times depleted.
Dissolved oxygen is required by fish and other aquatic organisms for respiration. Oxygen is also used for
decomposition of organic matter and other biological and chemical processes.
Water quality standards require that dissolved oxygen must always be above 4 mg/I (instantaneous.)
Water quality standards also require that the daily average must be above 5 mg/I. Low dissolved oxygen
tends to be common in stagnant pools in summer when water is warm. Low dissolved oxygen under other
conditions — in winter, for example — should be cause for concern, with consideration given to
investigating the source or cause.
6.6 TEMPERATURE
Temperature influences solubility of dissolved oxygen helps control the rate of reactions, metabolic rates
or organisms, and the toxicity of ammonia. High water temperatures can stress aquatic organisms, and
when high temperatures persist, they inhibit reproduction of many aquatic organisms.
Water temperature should be measured and documented in degrees Celsius. There is a State surface
water quality standard of 32' C. Temperatures measured higher than 32° C may be indicative of a thermal
discharge.
As an outfall screening indicator, temperature can sometimes be used to distinguish between two
different sources of water. In summer, ground water may be colder that surface water. In winter, sewage
may be warmer than stream water.
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7 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.
Table 4. Biological indicators and things to consider.
Biological Indicators
Things to Consider
Vegetation
Seasonal and recent weather conditions should 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 algal
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
The presence or absence of aquatic life in and around a water body can be
aquatic life
an indicator of the health of a water body. Document whether or not they
observe aquatic life.
8 REFERENCES
Center for Watershed Protection (CWP) and Robert Pitt, Ph.D. 2004. Illicit Discharge Detection and
Elimination: A Guidance Manual for Program Development and Technical Assessments. EPA Cooperative
Agreement X-82907801-0. Washington, D.C.
9 ATTACHMENT 1: ORI FIELD SHEET
The Outfall Reconnaissance Inventory (ORI) field sheet is on the next page.
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Attachment 1: OUTFALL RECONNAISSANCE INVENTORY(ORI)
Section 1: Backeround Data
Subwatershed:
Outfall ID:
Today's date:
Time (Military):
Investigators:
Form completed by:
Temperature ff ):
Rainfall (in.): Last 24 hours:
Last 48 hours:
Latitude:
Longitude:
GPS Unit:
GPS LMK #:
Camera:
Photo #s:
Land Use in Drainage Area (Check all that apply):
❑ Industrial
❑ Ultra -Urban Residential
❑ Suburban Residential
❑ Commercial
❑ Open Space
❑ Institutional
Other:
Known Industries:
Notes (e.g., origin of outfall, if known):
Section 2: Outfall Description
LOCATION
MATERIAL
SHAPE
DIMENSIONS (IN.)
SUBMERGED
❑ RCP ❑ CMP
❑ Circular
❑ Single
Diameter/Dimensions:
In Water:
❑ No
❑ PVC ❑ IIDPE
❑ Eliptical
❑ Double
❑ Partially
❑ Fully
❑ Closed Pipe
❑ Steel
❑ Box
❑ Triple
With Sediment:
❑ Other:
❑ Other:
❑ Other:
❑ No
❑ Partially
❑ Fully
❑ Concrete
❑ Trapezoid
Depth:
❑ Earthen
❑ Open drainage
❑ Parabolic
Top Width:
❑ rip -rap
❑ Other:
Bottom Width:
❑ Other:
❑ In -Stream
(applicable when collecting samples)
Flow Present?
❑ Yes ❑ No If No, Skip to Section 5
Flow Description
(If present)
Trickle
El Trickle Moderate El Substantial
Section 3: Ouantitative Characterization
FIELD DATA FOR FLOWING OUTFALLS
PARAMETER
RESULT
UNIT
EQUIPMENT
❑Flow #1
Volume
Liter
Bottle
Time to fill
Sec
Flow depth
In
Tape measure
❑Flow #2
Flow width
Ft, In
Tape measure
Measured length
Ft, hi
Tape measure
Time of travel
S
Stop watch
Temperature
°C
Meter
pH
pH Units
Meter
Specific Conductivity
µS/cm
Meter
Illicit Discharge Detection and Elimination: Technical Appendices D-3

Outfall Reconnaissance Inventory Field Sheet
Section 4: Physical Indicators for Flowing Outfalls Only
Are Anv Phvaical Indicators Present in the flow? n Yes n No (If Mn ,Skin to .Section S)
INDICATOR
CHECK if
Present
DESCRIPTION
RELATIVE SEVERITY INDEX (1-3)
El Sewage ElRancid/sour ElPetroleum/gas
El
—Noticeable from a
Odor
❑
El Sulfide El Other:
❑ 1
—Faint
❑ 2
—Easily detected
distance
Color
❑
❑ Clear [_1Brown
[_1Gray ❑ Yellow
❑ 1
—Faint colors in
❑ 2
— Clearly visible in
❑ 3
— Clearly visible in
❑ Green ❑ Orange
❑ Red ❑Other:
sample bottle
sample bottle
outfall flow
Turbidity
❑
See severity
❑ 1
— Slight cloudiness
❑ 2
— Cloudy
❑ 3
— Opaque
Floatables
El Sewage (Toilet Paper, etc.)
El Suds
❑ 1
Few/slight;
El 2
— Some; indications
❑ 3
- Some; origin clear
Does Not Include
❑
— origin
of origin (e.g.,
(e.g., obvious oil
Trash!!
❑ Petroleum (oil sheen)
❑ Other:
not obvious
possible suds or oil
sheen, suds, or floating
sheen)
sanitary materials)
Section 5: Physical Indicators for Both Flowing and Non -Flowing Outfalls
Are nhvsical indicators that are not related to flow nresent? n Yes n No (Tf Nn. ,Skin to ,Section h)
INDICATOR
CHECK if Present
DESCRIPTION
COMMENTS
Outfall Damage
El[:1Spalling,
Cracking or Chipping ❑ Peeling Paint
❑ Corrosion
Deposits/Stains
❑
❑ Oily ❑ Flow Line ❑ Paint ❑ Other:
Abnormal Vegetation
❑
❑ Excessive ❑ Inhibited
Poor pool quality
ElElOdors
El Colors ❑ Floatables El Oil Sheen
❑ Suds ❑ Excessive Algae ❑ Other:
Pipe benthic growth
❑
❑ Brown ❑ Orange ❑ Green ❑ Other:
Section 6: Overall Outfall Characterization
❑ Unlikely ❑ Potential (presence of two or more indicators) ❑ Suspect (one or more indicators with a severity of 3) ❑ Obvious
Section 7: Data Collection
1. Sample for the lab? ❑ Yes ❑ No
2. If yes, collected from: ❑ Flow ❑ Pool
3. Intermittent flow trap set? ❑ Yes ❑ No If Yes, type: ❑ OBM ❑ Caulk dam
Section 8: Any Non -Illicit Discharge Concerns (e.g., trash or needed infrastructure repairs)?
D-4 Illicit Discharge Detection and Elimination: Technical Appendices