Outfall Screening Guidelines and Procedures 2022

CITY OF
DURHAM
DESCRIPTION, GUIDELINES, AND PROCEDURES FOR
DRY WEATHER OUTFALL SCREENING
City of Durham — Department of Public Works
Stormwater & GIS Services Division
Water Quality Unit
Apri 12022
Reviewed by: Date:
Michelle Woolfolk, Water Quality Manager

Table of Contents
Introduction...........................................................................................................................................4
List of Common Initialisms and Acronyms..............................................................................................4
SafetyOverview.....................................................................................................................................4
Personal Protective Equipment............................................................................................................5
Injury Response and Reporting............................................................................................................5
SafetyAssessment...............................................................................................................................5
Hazardous Materials and Conditions................................................................................................6
HostileIndividuals............................................................................................................................6
RoadwayHazards............................................................................................................................6
OtherHazards..................................................................................................................................6
ConfinedSpaces..............................................................................................................................6
Dry Weather Outfall Screening Procedures............................................................................................7
General Procedure Overview...............................................................................................................7
Annual Dry Weather Outfall Screening Plans.......................................................................................8
Targeted Areas for Screening...............................................................................................................8
Performance Goal Setting....................................................................................................................9
Identifying Outfalls for Dry Weather Screening....................................................................................9
MajorOutfalls, Defined....................................................................................................................9
General Procedure for Identifying Major Outfalls.............................................................................9
Guidanceon Culverts.....................................................................................................................
10
Eligible Days for Dry Weather Screening............................................................................................
10
EquipmentPreparation.....................................................................................................................
10
Field Meter Calibration and Post-Check.............................................................................................11
Entryonto Premises..........................................................................................................................
11
Consent to enter premises.............................................................................................................
11
Procedure for Screening an Outfall....................................................................................................
12
Physical Observations Relevant to All Outfalls................................................................................12
Field Measurements and Testing for Flowing/Suspect Outfalls.......................................................
13
Evaluating Screening Results for Non-Stormwater Discharges........................................................
14
Water Samples for Laboratory Analysis..........................................................................................
14
Field Data Entry into Outfall Screening Database...............................................................................
15

Industrial Outfall Screening..
Industrial Outfalls, Defined
... 15
.. 15
Selection of Industrial Outfalls for Screening......................................................................................16
AppendixA—Sample Field Data Form..................................................................................................17

Introduction
This document contains a description of and procedures for implementing the City's IDDE dry weather
outfall screening program. This is part of a series of guidelines and procedures covering implementation
of the City's illicit discharge detection and elimination (IDDE) program.
The Water Quality Unit of the Stormwater & GIS Services Division has been conducting dry weather
outfall screening since 2008. Since then, the Unit has added staff to enhance dry weather outfall
screening, industrial inspections, and water quality assessment and monitoring. The Unit has also
developed resources critical for supporting illicit discharge identification and tracking, including stream
monitoring programs and digital GIS maps of water, sewer, and stormwater systems. Our Outreach and
Education programs have also enhanced public understanding of the impacts of illicit discharges while
advertising reporting mechanisms for pollution concerns.
Eliminating illicit discharges is a cost-effective means of restoring and protecting surface water quality.
Outfall screening is a useful component of a comprehensive illicit discharge control program. While
investigations rely on an educated public to identify possible pollution sources for investigation by staff,
outfall screening is a proactive program designed to detect illicit discharges unnoticed and/or
unreported by the public.
List of Common Initialisms and Acronyms
ANSI —American National Standards Institute
GIS —Geographic Information System
GPS —Global Positioning System
IDDE — Illicit Discharge Detection and Elimination
MS4— Municipal Separate Storm Sewer System
NOR— Notice of Requirement
NOV — Notice of Violation
NPDES — National Pollutant Discharge Elimination System
OSHA —Occupational Safety & Health Administration
WQ—Water Quality
Safety Overview
The City of Durham's most valuable resources are its employees. Under any set of circumstances, your
own safety is a priority over any investigation task. Field staff must continually be aware of potential
hazards when conducting an investigation. Where potential hazards exist, investigators must evaluate
the potential hazard and take appropriate precautions to decrease the chance of injury.
City employees must read and understand the City's safety policies. Safety Policy S-201: Safety Program
indicates that "Each individual is in the very best position to ensure his/her own personal safety, which

will impact, not only the individual but others in his/her immediate work environment." S-201 goes on
to list requirements that every City employee must observe. Safety Policy S-206: On the Job Accident
Reporting and Procedures establishes requirements for employees and supervisors that will result in
prompt and accurate reporting of an accident, injury, or near miss.
Personal Protective Equipment
All city employees are required to use Personal Protective Equipment (PPE) appropriate for the task or
work assignment. Staff may procure most commonly needed PPE from the dispensary at the Public
Works Operations Center. Please talk to your supervisor if you need a particular type of PPE not
otherwise provided.
As a baseline, steel- or composite -toed safety shoes are so often required to enter certain premises that
they should always be worn in the field. Safety shoes should be oil- and slip -resistant, since oil residue is
frequently encountered on the ground. Generally, knee-high wading boots are strongly recommended
to provide comfort, safety, and accessibility for screening staff.
City employees must read and understand the City's safety policies. Safety Policy S-201: Safety Program
indicates that "Each individual is in the very best position to ensure his/her own personal safety, which
will impact, not only the individual but others in his/her immediate work environment." S-201 goes on
to list requirements that every City employee must observe. Safety Policy S-206: On the Job Accident
Reporting and Procedures establishes requirements for employees and supervisors that will result in
prompt and accurate reporting of an accident, injury or near miss.
Injury Response and Reporting
The City of Durham general safety procedures are located on the City's intranet portal and in each
employee's hard -copy policy handbook. In the event of an emergency, call 911 or transport the injured
employee to the nearest hospital.
Employees are required to promptly report on-the-job accidents, injuries, and illnesses to their
supervisor and the Public Works Safety Officer, and follow the additional reporting requirements of
Safety Policy S-206-2: On the Job Accident Reporting.
All employees must be familiar with and follow procedures and deadlines for all Workers' Compensation
claims. If an injury occurs during field operations, the supervisor or another team member will be
responsible for transporting the injured employee for medical attention as warranted.
Safety Assessment
Field staff should be prepared to react to a variety of scenarios. Potential safety concerns should be
evaluated upon arrival at a screening location.

Hazardous Materials and Conditions
If hazardous materials have been released or there are other conditions that present danger to the
public, 911 should be called immediately. WQ staff are not trained in emergency response and therefore
should not remain within an active hazard site.
Hostile Individuals
If at any time while conducting field operations, staff find themselves in a confrontational situation with
a hostile person or persons, the staff member should attempt de-escalation. If de-escalation is
unsuccessful, the staff member should withdraw.
Animals, both domestic and wild, can also present a danger and investigators should use their best
judgment in determining their safety risk.
Roadway Hazards
In some cases, it may be necessary to park along a roadway, or it may be necessary to inspect, observe,
or sample from a catch basin or other structure along a roadway. Staff must be aware of potential
hazards from roadway traffic. Safety measures (such as activating vehicle safety strobe lights, wearing
reflective safety vests, and setting out traffic cones) should be implemented to reduce road hazards.
In rare cases, it may be necessary to implement a traffic control plan to safely access manholes or other
structures. Most often, a traffic control plan is implemented during investigations conducted jointly with
Water and Sewer Maintenance, which involves blocking a lane of traffic and providing traffic control -
signal staff to safely route traffic. Staff not familiar with traffic controls should consult with more
experienced staff, their supervisor, or the Public Works Safety Officer.
Other Hazards
Staff must be aware of other dangers of working in urban areas. Hazards that may be present include
sharps (glass shards, needles, wire, etc.), construction debris, uneven and slippery terrain, and trash.
Investigators must be vigilant to reduce the possibility of accidents and injury while conducting outfall
screening.
Staff should be aware of seasonal hazards such as exposure to cold, exposure to heat, insects and
snakes, and poisonous plants. Ticks and mosquitoes may carry insect -borne diseases such as Lyme
disease, Eastern Equine Encephalitis, and West Nile virus. Staff should take appropriate precaution in
selection of clothing, selective use of insect repellants, and a thorough check for ticks after every day in
the field. If an employee is especially sensitive to poison ivy, oak, or sumac then protective lotions or
clothing should be used.
Confined Spaces
Staff need to be especially aware of OSHA regulations regarding confined space entry. During the course
of an outfall screening, WQ staff members may need to enter a confined space. Certain types of
confined spaces must not be entered. A brief discussion on confined spaces follows below; however,
staff should familiarize themselves with the specific regulations regarding confined spaces.

29 CFR 1910 defines a confined space for general industry as follows:
Configurations of a work area that hinder the activities of employees who must enter, work in,
and exit them. A confined space has limited or restricted means for entry or exit, and it is not
designed for continuous employee occupancy. Confined spaces include, but are not limited to
underground utility vaults, tanks, storage bins, manholes, pits, silos, process vessels, and
pipelines.
Permit -required confined spaces (29 CFR 1910.146) contain hazardous conditions that pose a definite or
potential health risk which could result in a serious injury or death. These conditions include noxious
gasses, trapping and asphyxiating hazards, exposed live electrical wires, or unguarded machinery. WQ
staff should never attempt to enter a permit -required confined space. If an investigator is unsure of the
conditions of a work area, then the Public Works Safety Officer or the Safety Officer from the City of
Durham's Risk Management Department should be contacted to determine if the work area requires a
permit to enter. WQ staff members should keep in mind that if a space does not meet the regulatory
requirements of being a confined space, this does not imply that the space is without hazards. Relevant
examples of categorically classified spaces are listed below:
• Sanitary sewer manholes, lift stations, and wet sumps — Permit -required Confined Spaces
(noxious gasses)
• Stormwater pipes less than or equal to 18 inches in diameter — Not a Confined Space
• Stormwater pipes greater than 18 inches in diameter — Non -permit Confined Spaces'
• Catch basins less than or equal to 36 inches deep — Not a Confined Space
• Catch basins greater than 36 inches deep — Non -permit Confined Space*
• Stormwater manholes — Permit -required Confined Spaces (oxygen deficiency)
Dry Weather Outfall Screening Procedures
General Procedure Overview
The City's dry weather outfall screening methodology follows this general routine:
1) Develop an Annual Screening Plan to identify target outfalls, screening goals, and set special
criteria.
2) Organize outfalls dataset into clusters based on proximity for field workday efficiency.
3) Track and record precipitation to identify days eligible for dry weather screening.
4) Assemble necessary field equipment and PPE. Calibrate field meters and re -stock water test kits.
5) Travel and gain lawful entry to outfalls as necessary.
6) Conduct screenings and record data on field forms.
1 Requires the investigator to remain in constant contact with another staff member residing outside of the
entered space.

7) Observe and collect evidence of non-stormwater discharges to the drainage system and/or
surface waters. Report evidence of such discharges to the WQ group promptly via email and/or
phone.
8) Upon conclusion of field work, return to the laboratory to return equipment and clean and post -
check field meters.
9) Review field forms and enter data into the outfall screening database.
Annual Dry Weather Outfall Screening Plans
Dry weather outfall screening is typically conducted by the WQ Unit during the October -February and
July -August months. The October -February months are the chief period for conducting the majority of
screenings each year. These months are chosen because they are historically the driest weather period
in the year and because undergrowth and brush have receded, making outfall access more achievable.
The July -August months are generally used to finish or follow up on screening work from the earlier
period, or to perform special screening work identified in the Annual Plan.
Annual Plans are developed and written each year by the IDDE Supervisor. The Annual Plan is presented
and discussed at a pre -season Screening Meeting. These documents are stored on the WQ network
server, accessible by all field staff.
The Annual Plan addresses the following items:
1) Target subwatershed(s) and reason(s) for selection
2) Performance goals for outfall screening staff
3) Specific outfalls to be screened (including GIS shapefile for reference)
4) Field measurement requirements
5) Laboratory sample collection and delivery directions
6) Special project directives, as necessary
Where they differ from this Outfall Screening Guidelines and Procedures document, instructions and
guidance in an Annual Plan are controlling for that specific year.
Targeted Areas for Screening
Each subwatershed in the City is evaluated by the screening program on a rotating basis. However,
certain conditions may result in more frequent screening of certain subwatershed/drainage areas. These
conditions include:
• Record of an investigation initiated from outfall screening during previous years;
• Elevated pollutant concentrations at an ambient monitoring or special study monitoring site;
• Area of increased risk of an illicit discharge (e.g. downtown, areas of aged infrastructure); and
• State 303(d) listing status or Total Maximum Daily Loads (TMDLs) for receiving stream.

Once a watershed is selected for monitoring, outfalls may be sorted into priority groups, based on
several criteria:
• Downstream of storm sewer -sanitary sewer utility crossings
• Upstream of ambient monitoring sites with high fecal coliform colony count samples
• Downstream of facilities/complexes/neighborhoods with history of sanitary sewer discharges
• Locations of past outfall screenings where ammonia was measured >_ 2 mg/L
When organizing work plans, field staff should follow the priorities described in the Annual Plan.
Performance Goal Setting
The City's MS4 NPDES Permit requires procedures to specify the number of outfalls to be screened.
These performance goals are calculated annually based on a number of factors:
• Staffing levels;
• Evaluation of prior years' performance;
• Knowledge of target area impact on screening efficiency; and
• Impact of concurrent special projects and/or screening strategies.
These goals are written into each screening staff member's Employee Performance Evaluation Program
record and the Annual Screening Plan.
Identifying Outfalls for Dry Weather Screening
Major Outfalls, Defined
The City is required, by MS4 NPDES Permit, to screen "major outfalls" for illicit discharges. According to
40 CFR §122.26, a "major outfall" is:
... a municipal separate storm sewer 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 municipal
separate storm sewers 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).
General Procedure for Identifying Major Outfalls
The City's GIS work units created and maintain spatial datasets for all stormwater utility features. These
datasets may be viewed internally or externally from the City's network using any web browser.
Internally, staff may interact with these datasets using desktop GIS software (such as ESRI ArcGIS) and
perform basic analysis and cartography to prepare for each screening session.
In addition to a base map of features including streets, surface waters, parcels, jurisdictional limits, etc.,
two datasets are needed to guide screening efforts: 1) stormwater structures and 2) stormwater pipes.

The stormwater structures dataset includes locations and attributes for all MS4 inlets, outlets,
manholes, junctions, etc. This dataset does not include the diameter of MS4 outlets. To identify major
outfalls, the stormwater structures dataset must be joined with the stormwater pipes dataset. A spatial
join of these two datasets will allow the user to append diameters to each outlet structure. After
performing this operation, the user may execute attribute and location queries to identify major outfalls
(>_ 36 inches in diameter) within any target space.
This operation is typically performed by the IDDE Supervisor and the resulting dataset/shapefile is
provided to the screening staff. A more specific tutorial on performing the above GIS operations is
beyond the scope of this document.
Outfalls associated with industrial activities area addressed later in this document.
Guidance on Culverts
Culvert outlets may be included in the outfall dataset. Staff should assess culverts in close detail either
via GIS map or in person to evaluate whether they are eligible for screening.
A (simple) culvert is a structure that conveys water under a road, railway, or other obstruction. Contrast
this with an actual outfall, which is a point source where the MS4 discharges to surface waters.
Culverts are not eligible for screening unless:
1) One or more stormwater pipes outlet into the culvert; or
2) There is a high -risk sanitary sewer line (vitrified clay or HDPE) that crosses through the culvert.
Eligible Days for Dry Weather Screening
Screening staff are responsible for determining which work days are eligible for dry weather screening.
A day is eligible if there is less than 0.1 inches of precipitation recorded over the preceding 72 hours.
Staff should consult data from the weather stations closest to the annual study area in determining
eligibility. Rainfall data collected for evaluating eligibility will be recorded and stored on the WQ unit
network server Outfall program folder.
Equipment Preparation
PPE must be prepared, donned, and used according to City policy and the guidelines stated earlier in this
document.
Equipment necessary and recommended for screening includes:
1) Mobile phone (with app for viewing City GIS map data)
2) Camera
3) CHEMetrics field test kit
a. Sample cup
b. Ammonia ampoules, indicator solution, and comparators
c. Chlorine ampoules, indicator solution, and comparators

d. Detergents ampoules, indicator solution, and comparators
e. Waste collection containers
4) Field meters
a. pH
b. Specific conductivity
c. Dissolved oxygen
d. Temperature
5) Laboratory sample bottles (typically 3-4 sets)
6) Coolers with wet ice
7) Field data forms
8) Peristaltic pump assembly
9) Screening guidance documents, for reference
Field Meter Calibration and Post -Check
Commonly used water testing devices include pH pens, conductivity pens, dissolved oxygen probes, and
turbidity meters. All devices must be calibrated before and post -checked after each use. Refer to the
document, "Standard Operating Procedures for Water Quality Field Meter Calibration and Maintenance"
for instructions. A log must be completed to document device performance during each of these steps.
Entry onto Premises
The in situ nature of outfall screening requires entry onto property. While some outfalls may be located
on public property or within City easements and are therefore accessible without special considerations,
private property may only be entered with authorization.
All outfall screenings are "searches" for the purposes of considering private property rights. As
government agents, WQ staff members have a duty not to intrude on peoples' privacy. The Fourth
Amendment to the U.S. Constitution provides people with protection against unreasonable searches by
the government.
Outfall screening staff must obtain consent to enter private property. Failure to do so may result in
trespass charges/suits and invalidation of evidence collected for enforcement purposes.
In the absence of permission to search a property, only the acceptable way for an investigator to enter
property to conduct a search is to obtain a search warrant. Investigators considering this option must
discuss the situation with the IDDE supervisor. Refer to the WQ unit document "Guidance on
Administrative Search Warrants" for instructions and best practices should this be deemed necessary.
Consent to enter premises
Consent of a person who has control over, the right to joint access of, or authority over a property must
be granted before an investigator records observations or collects evidence from areas that would be
unreasonable to search.

Who maygrant consent?
Often, staff will be dealing with resident property owners, business owners, managers, and supervisors
who are explicitly authorized to grant consent to entry.
Tenants who lease property from landlords have possession of the property and the power of consent
to entry. A landlord may not grant valid consent to enter property leased to a tenant (unless the lease
specifies an exception). When dealing with co -tenants or co -owners, any of the tenants or owners may
grant valid consent to enter the premises. However, it only takes a single co -tenant or co-owner to
object or revoke the consent.
A non -owner or non -manager business employee may have authority to grant valid consent to enter the
premises if: 1) a higher-up has given them the appearance of authority (such as a uniform or "manager"
name tag/title); and 2) the staff member reasonably believes the employee to have authority, based on
that appearance.
When in doubt as to the validity of consent, a staff member should not enter the premises. Except in the
case of emergency, if an owner, manager, or other supervisor is not available, it is usually best to return
another time when such a person is available.
Steps to follow in requesting consent to enter and inspect:
1. Identify yourself by name
2. Show your City ID badge
3. Request to speak with an owner, tenant, manager, supervisor, or other person in charge
4. Explain the purpose of your visit
5. Request permission to enter and conduct your screening
The staff member should always include in their notes the names of individuals who granted, denied, or
revoked consent to enter. Once granted, consent may be limited or revoked at any time.
Procedure for Screening an Outfall
For safety and efficiency, outfall screening is performed in teams of two staff members. Additional staff
members mayjoin this team for training or special projects as necessary.
All screening observations and sampling must occur at the actual outfall (in situ). If in situ conditions
cannot be met, the screening must be declined and staff should record the reason for such a decline. All
observations and measurements described below must be recorded on field data sheets. Any additional
conditions relevant to identifying illicit discharges must be noted on the field data sheet in the "notes"
section. A sample of the outfall screening data sheet is provided in Appendix A — Sample Field Data
Form.
Physical Observations Relevant to All Outfalls
Flow
Describe the discharge rate, if any, from the outfall, using the closest qualitative estimate:

• None
o No discharge from the outfall
o No pool present at outfall or no pool with pollutant indicators present
• Trickle
o A slight discharge that does not maintain a constant stream flow
• Moderate
o Enough discharge to create a constant stream flow
• Substantial
o Significant discharge indicative of a piped stream
• Suspect pool with pollutant indicators
o An outfall with no discharge, but pooled water has indicators of illicit discharge (color,
odor, sheen, etc.)
Other Physical Observations
Other physical characteristics and observations may be recorded according to program needs and best
practices. Field data sheets will be reviewed and updated as necessary and will direct staff to collect
specific observations. Common physical observations include:
• Odor
• Color
• Turbidity
• Floatables
• Outfall structure damage
• Outfall obstruction
• Deposits and staining at outfall
In addition to the presence or absence of each of the above observations, field sheets include space and
guidance for evaluating the severity and description of the observation. Severity is graded on a scale
from 1 to 3, where 1 is the least detectable and 3 is the most detectable.
Field Measurements and Testing for Flowing/Suspect Outfalls
In -situ field measurements and tests are used to assess discharges for potential non-stormwater
discharges. Field measurements require that instruments be introduced at the point of discharge or
within the suspect pool. Water samples for tests must be collected at the same location.
Typical field measurements include:
• Temperature
• pH
• Conductivity
• Dissolved oxygen

Field water tests are performed using CHEMetrics kits. At a minimum, ammonia and chlorine tests must
be performed at all flowing outfalls and at all outfalls with suspect pools. Other tests, such as
detergents, may be performed at the discretion of the field staff based on other observations and
indicators. Instructions for the proper use of CHEMetrics kits are included in their carry case.
Evaluating Screening Results for Non-Stormwater Discharges
After evaluating and recording all screening indicators, staff must determine the likelihood of a non-
stormwater discharge from the outfall. This is best decided in the field before leaving the outfall area.
The benchmarks in the table below are used by the WQ unit as indicative of a non-stormwater
discharge. A measurement outside of a benchmark will typically trigger initiation of an IDDE
investigation into a potential non-stormwater discharge. Generally, a benchmark exceedance of
conductivity alone will only trigger collection of a laboratory sample (see below).
Indicator
Benchmark
Ammonia (mg/L)
>_ 1
Detergents/MBAS (mg/L)
Any detection
Conductivity (µ
>_
1,000 (Oct-Feb)S/cm) > 800 (Jul -Aug)
Chlorine (mg/L)
Any detection
pH (SU)
<_ 6 or >_ 9
Other physical indicators such as odor, color, turbidity, and floatables may independently or collectively
be suggestive of a non-stormwater discharge. Screeners evaluate the severity of indicators observed to
estimate the probability of a non-stormwater discharge:
• Obvious discharge — a non-stormwater discharge is plainly present through sensory evidence
• Suspect discharge — one or more severity 3 indicators are observed
• Potential discharge — two or more indicators are observed
• Unlikely discharge — no indicators observed
Obvious and Suspect discharges are referred for IDDE investigation. Review of additional data sources
such as a map of nearby investigation history, prior screening results, and proximity of sanitary utilities
should be considered when referring Potential discharge evaluations for IDDE investigation.
Water Samples for Laboratory Analysis
Samples must be collected and handled in accordance with the WQ document, "Standard Operating
Procedures for Water Chemistry Sampling." Laboratory analyses will be pre -arranged by the IDDE
Supervisor with the laboratory service and described in the Annual Outfall Screening Plan.
Laboratory samples for outfall screening are collected under the following circumstances:
1) Conductivity measures
a. October -February: >_ 1,000 µS/cm and no other field measurement meets a trigger

b. July -August: >_ 800 µS/cm and no other field measurement meets a trigger
OR
2) A sewage discharge is identified
All samples must be properly preserved and placed on wet ice, or stored in the WQ lab refrigerator until
they can be picked up by a lab courier or dropped off at the designated lab. Analysis hold times and
laboratory operating hours will dictate the required timeliness of sample delivery. All sample bottle
labels must be properly and clearly completed. The sample ID is always recorded as the outfall's facility
ID. All bottles must be accounted for on and accompanied by a laboratory Chain of Custody form.
Laboratory analysis of samples typically include a combination of the following, depending on the nature
of the suspect discharge:
• Ammonia
• Nitrate+Nitrite
• Fecal coliform bacteria
• Fluoride
• Zinc, total
• Copper, total
• Detergents
• Potassium, total
Field Data Entry into Outfall Screening Database
After field forms are checked for errors and completeness, their contents are promptly entered into the
Outfall Screening Database. Paper field forms are they scanned to PDF and retained on the WQ network
server for archival purposes. This database has multiple data validation and error -checking mechanisms
built in as well as redundant data backups to a Public Works SQL server. Screening data are also live -
linked to City GIS for internal viewing of spatially -distributed results.
Directions for interacting with the Outfall Screening Database is beyond the scope of this document.
Industrial Outfall Screening
Field and data management procedures for industrial outfall screening are identical to those defined
above. Industrial outfall screening only differs in identification and selection of structures to be
evaluated.
Industrial Outfalls, Defined
Industrial outfalls are a subset of major outfalls, earlier defined in this document under 40 CFR §122.26:
...for municipal separate storm sewers 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).
Selection of Industrial Outfalls for Screening
The WQ screening program identifies industrial outfalls by first identifying industrial facilities subject to
the WQ Stormwater Inspections Program. Using City GIS resources, outfalls associated with activity at
those industrial facilities can be located. Occasionally, a facility's private stormwater drainage system
may be unmapped. In these instances, screeners will visit the site, identify the outfalls, and collect
precise GPS coordinates to accompany field screening data. Upon returning to the office, screeners may
submit outfall coordinates and attributes to the Public Works GIS Unit to create records in the
stormwater structures geodatabase.
Selection of industrial facilities to be screened is conducted by the IDDE Supervisor using priorities
defined in the Stormwater Inspections Program Guidelines document. Facilities to be screened are listed
in the Annual Outfall Screening Plan. Typically, screening is conducted by trained inspectors
contemporaneously with scheduled site compliance inspections.

Appendix A — Sample Field Data Form
Facility ID
Team
Date
Time (24 hour)
ISWI Fachliry, ID
Database entry by
Auessibiliry
Access,lb'.e
Inacc ssibe (reason)
Entry Consent
Notneeded
Denied
Granted
Granted by:
Flow?
None
Suspect pool with pollutant indicators
Trickle
Moderate
Substantial
Submerged/Buried?
No
Bottom >SO% 100%
Structure Damage
Yes
No
Deposits/stains
None
OiN Algae
Other (notes)
Indicator
Present?
Description
Severity
1—fain:
Sewage Rancid/Sour
Odor
re, No
Petroleum Sulfide
2—Easily Detected
Other (notes)
3—Notice from distance
1—Fant in sample bottle
Brown Grey Yellow
Color
Yes No
Green Orange
2—Obvious in sample bottle
Red Other (notes)
3— Obvious in outfal I flow
1—Slightly cloudy
Turbidity
Yes No
See severiry
2—Cloudy
3—Opaque
1—Few/slight
Sewage Suds
Floatables(not trash)
Yes No
Petroleum
2— Sane, type unlmown
Other (rates)
3—Sane, type known
Temperature (-C)
Conductivity (µ5/cm)
ply
DO (mg/L)
DO (%)
Ammonia (mg/L)
Chlorine (mg/L)
Detergents (mg/L)
Copper (mg/L)
phenols (mg/L)
Lab Sample?
Yes
No
Obvious discharge
lll� Discharge PM,Ml
Suspect Discharge
(see definitions)
Potential Discharge
Unlikely Disctarge
Definitions:
Suds: tight foams with strong staying power beyond points of water turbulence
Obvious discharge: an illicit discharge is plainly present without need to sample
Suspect discharge: Rowing outfall with one or more severhy 3 indicators
potential discharge: outfall with presence of two or more indicators
Unlikely discharge: no nd icator of illicit discharge