Durham Outfall Screening and Monitoring SOP (Oct 2015)

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CITY OF MEDICINE
CITY OF DURHAM DRY WEATHER OUTFALL
SCREENING AND MONITORING
STANDARD OPERATING PROCEDURES
City of Durham
Stormwater & GIS Services Division
Water Quality Unit
October 2015
City of Durham Stormwater &GIS Services—[phone]
www.DurhamNC.gov/stormwater
Design/Plan Review—Drainage/Flooding Concerns—Floodplain Information
Stormwater Public Education —Surface Water Quality

Approval Sheet
Prepared by: Date:
John Cox, Water Quality Manager
Approved by: Date:
Paul Wiebke, Assistant Public Works Director
CITY OF DURHAM DRY WEATHER OUTFALL SCREENING OCTOBER 1, 2015 (DRAFT)
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Foreword
This manual contains the Standard Operating Procedures (SOP) and measures to be used by Stormwater
& GIS Services' Water Quality Section for inspecting stormwater outfalls (discharge points). This SOP also
contains procedures for testing/screening dry weather flows for the presence of indicator pollutants to
assess whether the dry weather flow is an illicit discharge. The procedures in this manual are adapted
from a combination of guidance documents, field experience, and instructional manuals received with
testing equipment.
Because outfall monitoring encounters a broad range of scenarios in the field, modifications to these
SOP may be necessary in specific conditions. Any deviations from the procedures in this manual should
be documented.
This manual shall be made available to all staff and shall be studied by those staff members with
principle responsibility for conducting outfall screening. New employees are expected to read and
become familiar with the manual before commencing with field sampling. Periodically, the manual will
be updated to cover changes, such as the addition of new testing methods.
This manual is part of a series of SOPs and guideline documents covering other components of the City's
illicit discharge detection and elimination program. Document in the series include:
"Procedure for Completing the Water Quality Complaint Form (paper form and database form),"
provides procedures for properly filling out the Water Quality Complaint forms and database entries.
"Illicit Discharge Detection and Elimination Investigations — Standard Operating Guidelines" which
provides information on common types of illicit discharges, initiation of investigation, permission to
enter property, administrative search warrants, methods to isolate sources, and collection and control
of evidence.
"Weekend SW Code Enforcement Procedures," which provides information on procedures and
schedules for weekend targeted enforcement of the Stormwater Ordinance.
"Guidelines for Enforcement of the Stormwater Pollution Control Ordinance (Article V of Durham City
Code of Ordinances)," which provides guidance for enforcement and assessing civil penalties resulting
from violations of the City Stormwater Ordinance enforcement of Article V of Durham City Code of
Ordinances: Stormwater Management and Pollution Control, Sections 70-492 through 70-542.
Staff members investigating sources of contamination are expected to be familiar with sections of ".
Illicit Discharge Detection and Elimination A Guidance Manual for Program Development and Technical
Assessment," Center for Watershed Protection and Robert Pitt, October 2004 (CWP, 2004).
Staff members are also expected to be familiar with information contained in the City's Stormwater
Management Plan (SWMP). Staff members involved in illicit discharge program should be familiar with
Section 3.1.3 and section 7.4 of the SWMP.
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Disclaimer
The mention of trade names or commercial products in this handbook is for illustration purposes and
does not constitute endorsement or recommendation for use by the City of Durham, Stormwater & GIS
Services Water Quality Unit.
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Table of Contents
ApprovalSheet............................................................................................................................................ ii
Introductionand Purpose...........................................................................................................................2
Definitions.................................................................................................................................................
3
History of the City's Outfall Screening Program..........................................................................................4
Dry Weather Outfall Screening Methodology.............................................................................................5
IdentifyingMajor Outfalls.........................................................................................................................5
Targeted Areas for Screening....................................................................................................................
6
Field Screening and Data Collection.........................................................................................................7
MobileTechnology................................................................................................................................7
Database Features and Functionality.....................................................................................................10
MapTab..............................................................................................................................................11
OutfallTab...........................................................................................................................................15
ReportsTab.........................................................................................................................................18
Preparing for Technical Difficulties in the Field......................................................................................19
Preparation Prior to Leaving for the Field..............................................................................................19
Procedure for Screening an Outfall........................................................................................................19
PhysicalObservations.........................................................................................................................19
In -Situ Field Measurements................................................................................................................21
FieldWater Analysis Tests..................................................................................................................
21
TrackingDischarges to a Source................................................................................................................21
Procedures for Sample Collection and Removing the Source of the Discharge.....................................22
QualityAssurance......................................................................................................................................
23
References.................................................................................................................................................
23
APPENDIX A: Backup Field Form for Dry Weather Outfall Screening.......................................................24
APPENDIX B: Typical Equipment and Supplies Used During Dry Weather Outfall Screening...................25
APPENDIX C: Flow Chart for Dry Weather Outfall Screening....................................................................26
APPENDIX D: CHEMetrics Methods...........................................................................................................27
APPENDIX E: Interpreting Field Results - Observations, CHEMetrics Results and Physical Measurements
.......................................................................................................................................................
30
APPENDIX F: CHEMetrics Waste Disposal and Segregation.....................................................................40
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APPENDIX G: Exceptions to Prohibited Discharges...................................................................................45
APPENDIX H: GIS Symbology for the Outfall Screening Database............................................................46
APPENDIX H: Summary of Outfall Screening Results 2008 through 2014................................................50
Introduction and Purpose
The Clean Water Act (CWA) includes provisions that require municipalities with populations greater than
100,000 to apply for a National Pollutant Discharge Elimination System (NPDES) permit. These permit
holders are known as Phase I communities. The City of Durham (City) was issued their first Phase I
NPDES permit in 1994 (permit # NCS000249). This permit authorizes the City to discharge stormwater
runoff from its Municipal Separate Storm Sewer System (MS4) to receiving waters within the Cape Fear
and Neuse River basins. Such discharge must be controlled, limited, and monitored in accordance with
the permit and the City's Stormwater Quality Management Plan. This permit is renewed every four
years.
Section D of the City's NPDES permit requires implementation of an illicit discharge detection and
elimination (IDDE) program. Section D 1 outlines the objectives and requirements for IDDE as follows:
• Detect and eliminate illicit discharges, including preventable spills and illegal dumping, to
the permittee's MS4.
• Implement appropriate enforcement procedures and actions.
• Maintain a map showing the permittee's major MS4 outfalls to state waters receiving
discharges.
• Inform employees, businesses, and the general public of hazards associate with illegal
discharges and improper disposal of waste.
• Prohibit illicit discharges and connections.
Section D 2 requires the implementation of best management practices (BMPs) for IDDE. The listed
BMPs include maintaining a current map showing major outfalls and receiving streams, and conducting
inspection/detection program to detect dry weather flows at MS4 outfalls in targeted areas. The
measurable goals listed include maintaining written Standard Operating Procedures (SOPS) for detecting
and tracing the sources of illicit discharges and for removing the sources or reporting the sources to the
State to be properly permitted. SOPS shall specify a timeframe for monitoring and how many outfalls
and the areas that are to be targeted for inspections. This document is intended to fulfill this permit
requirement.
Stormwater regulations adopted in 1990 (40 CFR 122.26), required the MS4 permit application to
identify known MS4 outfalls and to conduct field screening analysis for illicit connections and illicit
discharges (40 CFR 122,26 (d)(1)(iii)(D)) at major outfalls or selected screening points. Samples collected
during dry weather were to be screened for pH, chlorine, copper, phenol, and detergents (or
surfactants). At that time cities had not yet mapped their drainage systems, and the regulations allowed
field screening to be conducted either at major outfalls or at other outfall points identified through a
grid system to provide coverage.
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Subsequent guidance developed for EPA by the Center for Watershed Protection and Robert Pitt, Ph.D.'
suggests that pipes smaller than those defined as major outfalls may contain illicit discharges; CWP
recommends that sampling only major outfalls may miss discharges. This guidance appears to
appropriate for dense cities such as Baltimore (CWP) and Birmingham (Pitt).
The City of Durham has explored several different strategies over the last fifteen years in an effort to
identify approaches that are effective and efficient in our community. Illicit discharges has been found
throughout the city, although they tend to be more concentrated in areas of older development where
the infrastructure old. The City has tried the strategy of inspecting in all outfalls in Northeast Creek. As
shown in Appendix H, in 2009-10 the strategy of inspecting all pipes except driveway pipes and culverts
was not as effective as in subsequent years; screening took longer and yet resulted in fewer
investigations. Since 2010, the process of identifying outfalls to be screened has been refined several
times to focus on inspecting outfalls that drain 50 acres. Although the subsequent years focused on
major outfalls, teams were asked to be opportunistic regarding smaller pipes flowing during dry
weather.
After completing a second round of dry weather outfall screening in 2003, the City discontinued the
program for several years in order to investigate other methods. The collected samples for a bacteria
source tracking to identify the source of fecal indicator bacteria (FIB) in Northeast Creek using multiple
antibiotic resistance testing. The City also used intensive collection of stream samples analyzed for fecal
indicator bacteria involving two months of twice weekly sampling at closely spaced stations on a stream
segment 8 to 10 samples per site; statistical assessments of central tendency were used to identify
hotspots for intensive investigation.
The City has also used follow-up sampling of outfalls with previous "hits" to assess whether there may
have been more than once source.
Dry weather outfall screening may miss illicit discharges that are intermittent or rare. Substitution of
other methods may be appropriate on a case -by -case basis.
Definitions
As defined in 40 CFR 122.26(b):
Outfall means a point source as defined by 40 CFR 122.2 at the point where a municipal separate storm
sewer discharges to waters of the United States and does not include open conveyances connecting two
municipal separate storm sewers, 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.
Major outfall means a major municipal separate storm sewer outfall.
Major municipal separate storm sewer outfall (or "major outfall") means a municipal separate storm
sewer outfall that discharges from a single pipe with an inside diameter of 36 inches or more or its
1 Center for Watershed Protection and Robert Pitt. 2004. Illicit Discharge Detection and Elimination A Guidance
Manual for Program Development and Technical Assessments.
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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).
Municipal separate storm sewer means a conveyance or system of conveyances (including roads with
drainage systems, municipal streets, catch basins, curbs, gutters, ditches, manmade channels, or storm
drains):
(i) Owned or operated by a State, city, town, borough, county, parish, district, association, or other
public body (created by or pursuant to State law) having jurisdiction over disposal of sewage, industrial
wastes, storm water, 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 CWA
that discharges to waters of the United States;
(ii) Designed or used for collecting or conveying storm water;
(iii) Which is not a combined sewer; and
(iv) Which is not part of a Publicly Owned Treatment Works (POTW) as defined at 40 CFR 122.2.
Waters of the United States means 1. All waters which are currently used, were used in the past, or may
be susceptible to use in interstate or foreign commerce, including all waters which are subject to the
ebb and flow of the tide; 2. All interstate waters, including interstate wetlands; 3. All other waters such
as interstate lakes, rivers, streams (including intermittent streams), mudflats, sand flats, wetlands,
sloughs, prairie potholes, wet meadows, playa lakes, or natural ponds of which the use, degradation, or
destruction would affect or could affect interstate or foreign commerce including any such waters: a.
Which are or could be used by interstate or foreign travelers for recreational or other purposes; b. From
which fish or shellfish are or could be taken and sold in interstate or foreign commerce; or c. Which are
used or could be used for industrial purposes by industries in interstate commerce; 4. All impoundments
of waters otherwise defined as waters of the United States under this definition; 5. Tributaries of waters
identified in paragraphs (1) through (4) of this definition; 6. The territorial sea; and 7. Wetlands adjacent
to waters (other than waters that are themselves wetlands) identified in paragraphs 1 through 6 of this
definition.
Geographic Information Systems (GIS) means a system designed to store, manipulate, analyze and
manage geographical data.
Stormwater Node means a point or feature in GIS relating to the stormwater drainage system.
History of the City's Outfall Screening Program
The City has implemented various programs to identify and eliminate illicit discharges since 1994. Initial
outfall inspection and screening efforts were conducted by contracted consultants to aid in the
development of the City's MS4 permit. Before the City had mapped the stormwater piping
infrastructure, the City's consultants used coarse USGS topographic maps to identify drainage
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catchments draining an average 60 acres each. The outlet of each drainage catchment was identified as
a major outfall. Maps of the major outfalls were submitted with the City's permit application, and initial
inspections were conducted by the consultants (Ogden). Beginning in 1996, the City developed in-house
capabilities for conducting dry weather monitoring, stream monitoring and illicit discharge enforcement.
In 1998 and 1999 staff inspected and screened all major outfalls within the City, including more than 800
outfalls during dry weather.
Regular, ongoing outfall inspections were discontinued in 1999 in favor of short -duration, intensive
stream monitoring. This approach involved collection of during dry weather at closely -spaced sampling
stations, with laboratory analysis of samples for fecal coliforms. Sample locations were sometimes
adjusted based on results of the first 2 or 3 samples, sometimes adding a station in between two
stations reporting high values, while dropping a station reporting lower values. After a minimum of six
samples were collected from each site, fecal coliform results were compared between sites to identify
hotspots. Additional source identification, including outfall screening, was performed to identify the
sources associated with the hotspots. In areas of older development, bisecting sites with high results
sometimes resulted in samples sites as closely spaced as every block. This approach tended to focus
efforts on the most significant sources, even when the source was an intermittent discharge. This
approach was discontinued when the City's ambient stream monitoring program shifted from two dry -
weather samples per quarter to a more comprehensive and representative program involving fixed
interval monthly sampling.
In 2007 the City reestablished routine outfall inspection and screening program. Beginning in the 2010-
2011 outfall screening season, a new method of designating outfalls to be screened was initiated. In
order to expedite screening, only outfalls designated as "Ogden" points were screened. Ogden points
were identified by the consulting firm Ogden, who delineated drainage areas within City subwatersheds
by overlaying USGS topography maps over the storm drain system. The outfall furthest down gradient
that drained the delineated drainage area was designated as an Ogden point. Ogden points drain areas
of approximately 50 acres in size and approximately 1 acre in industrial areas. Due to differences in map
scales, Ogden points frequently did not overlay the intended outfall. Screeners had to use their best
judgment when assigning an Ogden point to what was assumed to be the intended outfall. Associated
screening data were stored in attributes tables within ArcGIS.
Dry Weather Outfall Screening Methodology
The City's dry weather outfall screening methodology consists of the following components:
• Identifying major outfalls,
• Targeting areas for screening,
• Field screening and data collection, and
• Investigation initiation, if applicable.
Identifying Major Outfalls
In early 2014, the Ogden approach for identifying selecting major outfalls was abandoned in favor of a
GIS-based approach for selecting major outfalls. The GIS-based approach is more adaptable to changes
in the city, such as annexation and new development. It is also far more efficient because it is query -
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based and does not require staff to manually select major outfalls, as was the case with the Ogden
method. It also removes the arbitrary selection of outfalls as the GIS-based approach selects major
outfalls by the facility ID number.
The GIS group within Stormwater & GIS Services developed the GIS-based approach in selecting major
outfalls. The GIS group maintains the stormwater pipes and structures GIS layers. They created an
outfall layer consisting of stormwater structure points. Those stormwater structures are coded by type
and task. A task of "outlet" meant the end of a pipe system, or outfall. The "Select by Location"
function was used to calculate the outfall diameters. As a result, outfall diameters were coded with the
diameter of the connecting pipe. Drainage area of outfalls was calculated by tracing the stormwater pipe
network upstream to estimate the total area draining to the outfall. The resulting outfalls layer was
extracted to a data table in Microsoft SQL Server and then queried to meet the qualifications for major
outfalls as determined by 40 CFR 122.26(b).
The initial resulting layer yielded about 2,000 major outfalls. Culverts were found to have a task of
"outlet" but do not meet the screening criteria and were then filtered out of the qualifying layer. As a
result, the existing layer now has about 1,200 major outfalls.
Targeted Areas for Screening
Dry weather outfall screening can be performed year-round and is generally divided into summer
screening (April through September) and winter screening (October through March). During winter
screening, outfalls may be located and evaluated more easily as vegetation is dormant and less
prevalent in the environment. For winter screening, specific watersheds are selected on a rotating
schedule until all major outfalls in the City are screened. Summer screening is not on a rotational
watershed basis like winter screening. Summer screening is targeted screening based on the following
criteria:
• Record of an investigation initiated from outfall screening during previous years;
• Elevated pollutant concentrations at an ambient monitoring or special studies 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.
Areas of aging infrastructure, including downtown, may have piping networks that drain larger than 50
acres, in some cases up to 500 acres. As discussed further below, ammonia is the indicator most likely
to identify illicit discharges. Ammonia can disappear during travel through a variety of processes.
Ammonia can be volatilized or else converted to oxidized forms. Thus, while ammonia is a very sensitive
indicator when monitoring in smaller systems, it is rarely a good indicator in streams or even in large
pipe networks. In order to identify whether illicit discharges are present in large pipe networks, it is
essential to sample locations from within the network, such as from manholes. Because there may be
multiple sources present, it is often helpful in large networks to sample much smaller areas, down to 20
acres or less. Identification of reasonably accessible manholes, catch basins, or other structures for
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sampling is best done in the field. The procedures discussed below provide a means for identifying new
outfalls to sample.
Once a watershed is selected for monitoring, areas of industrial land -use and segments of the storm
drain system that are crossed by the sanitary sewer system are further prioritized. These areas are
prioritized due to increased likelihood of ammonia discharges and/or industrial illicit discharges. In
general, winter screening assesses larger drainage areas (roughly 50 acres in non -industrial areas and so
the entire City's MS4 can be evaluated within a roughly S-year period. Summer screening is intended to
target a small drainage area.
Field Screening and Data Collection
Prior to the 2014-2015 winter outfall screening season, field data were entered into GIS. GIS was either
accessed directly onto the field computers or through the City's virtual private network (VPN) via an
internet connection and remote desktop. These GIS-based processes were somewhat complicated and
required multiple steps of field prep, data transfer, and data processing. Additionally, these processes
increased the chance of entering incorrect data or inadvertently erasing data collected in the field.
Beginning with the 2014-2015 winter outfall screening season, screeners began using a Microsoft
Access -based platform for field data collection. This centralized database, housed on City of Durham
servers, was accessed through the VPN via an internet connection and remote desktop. The Access -
based platform was easier to use and included several accuracy and efficiency advantages versus the
GIS-based platform. The Access database included a web -based mapping feature that could load faster
than GIS-based maps. This database could be updated by multiple field teams simultaneously without
overwriting other team's data entries. Additionally, this database eliminated the need for data transfers
and redundant data processing. There are also built-in safeguards to ensure data are entered
completely and reduced the chance for erroneous entries. Furthermore, this database has a built-in
reporting mechanism which was not available in the GIS-based platform.
Mobile Technology
Field data are collected in the field by utilizing mobile personal computers (PCs) and a Wi-Fi connection.
The mobile PC's can be used like traditional computers by attaching a mouse and keyboard or it can be
used as a tablet with its touchscreen interface. Screeners are equipped with mobile hot spots giving
them access to the internet and the ability to remote desktop into their office, desktop computers. This
ability to remote desktop into the office has cut down on preparation time and helped with the
investigation process once illicit discharges are detected.
For a screener to be able to remote desktop into their computer they must first get permissions to
access the City of Durham virtual private network (VPN). Once that is obtained the screener must find
out their computer's name. This process can be seen in Figure 1 and is described below:
First go to the start menu and right click on "Computer." Select "Properties" and the computer name
will be located under "Computer name, domain, and workgroup settings."
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Demote Desktop
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Database Features and Functionality
Help
The ability to remote desktop into the office gives access the outfall screening database that went live in
October of 2014. The database was designed to give the screener a single location to enter in screened
data, edit the outfall screening GIS layer, have real time database and GIS updates to prevent
overlapping of the two teams, grant access to all the GIS layers necessary to find outfalls and trace illicit
discharges, and compile statistics for reporting. The outfall screening Access database path is:
F:\GIS\Files\PKG\OUTFALLSDB\BIN\OutfaIlsDB.BAT
The outfall screening database is stored in a Microsoft SQL Server database in the city's "DURHAM-
PWAPP" server. The "PWDB" database houses the two outfall screening tables: outfalls and screenings.
Database users access theses tables with read and/or write access via the Access front-end database
listed above. The front-end pulls data directly from the server which allows specific users to make
changes. Note, not everyone has edit rights to the outfall screening database. Using Access forms,
users can select one of the proposed outfalls for screening, or, users can also potentially select any
stormwater structure for screening. This was done intentionally in the event that a screener discovers a
contaminated outfall and then decides to trace the outfall upstream and screen the upstream
stormwater structure. Screenings are saved on a separate table since one outfall can be screened more
than once.
The built-in GIS web map is a geospatial representation of the outfalls and screenings tables. Screenings
and outfalls have X/Y geographic data that allows for mapping. The web map contains a published map
service that pulls the outfall and screenings data directly from the server. Since the web map pulls data
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from the same tables being edited or viewed in the Access forms, any screenings made in the Access
front end will instantly update the map. In other words, adding a screening in Access will add a
screening on the map.
There are three main tabs when the database is opened. The outfall tab will be where most of the work
is done. The "Map" tab has a larger map than the "Outfall" tab allowing for a broader scale. The
"Reports" tab is used for the compiling of statistics.
Map Tab
These functions can be carried out under the "Outfalls" and "Map" tabs. When opened the entire city
limits will be visible and divided into watersheds. Figure 3 points out key functions of the map tab.
Zoom -Zooming in and out can be accomplished by the +/- buttons, the mouse scroll -wheel, or
by pressing two fingers against the screen and moving them closer to zoom in or further away to zoom
out.
Magnifying Glass —The magnifying glass is the default function in the map and is used for searching
addresses. When clicking on the magnifying glass a pull down menu will appear. Features in this pull
down menu include identify, find, measure, bookmarks, GPS, and layers.
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OCTOBER 1, 2015 (DRAFT)
PAGE 11

Figure 3. Map tab with highlighted functions
Address - To search for an address make sure the magnifying glass is selected, type in the address, and
hit enter. The map will zoom into the area and place a bull's-eye over the address.
Identify — When information about a certain feature is needed use the identify function. Once identify
is chosen, select the layer needing to be identified and then click on the feature on the map.
Information about that feature will pop up on the right side of the map. Figure 4 gives an example of
using the identify function to access an outfall's specifications
Outfall Inspections
Outfall Screening
Contaminated
ouYfa71 Inspections
_ Ouffall inspections (NO PIPE DIAMETER)
. Stormwater
SCMSBdMPS
y' StormwaferDrains
Stormwater Pipes
Stormweter Channels
Storm Sewersheds
Water
Wafer Facilities
Wafer Finings
Wafer Sampling Station
Wafer Pump
Fire Hydrant
Wafer Meter
Wafer Valve
Wafer Control Valve
Wafer Lateral
Transmission Mains
Wafer Mains
Sewer
Sewer Facilities
E�rinit9 Monitoring Sites
Clean Out
Control Valve
Manhole
N� ,i System Valve
5 Gravity Main
o Lateral
Forge Main
Streets
' Street Centerlines
+ Gravel Streets
_ State streets - City maintains
BaseMap
Street Names (LABELS)
Choose feature to
be identified ; a
's l
Ellerbe Creek
i i 1 1 Nri rrre sannns
Figure 4. Identify function example
Feature
information
*_Qj . o,_ 4
Naples Pl
lLLS•li F.� A ', �'A
,cheek Rd;
N.m Lock 18 W
Find — To locate any stormwater node you can use the find function. Select "Find" and then type in the
facility ID # of interest.
Measure —The measure function can be used 3 different ways through a drop down menu:
CITY OF DURHAM DRY WEATHER OUTFALL SCREENING OCTOBER 1, 2015 (DRAFT)
STANDARD OPERATING PROCEDURES PAGE 12

1. Location — gives GPS location in XY coordinates, Degrees -Minutes -Seconds, Decimal Degrees,
and Decimal Minutes. A white circle indicates location of interest. Figure 5 gives an example of the
location function giving the XY coordinates of outfall #99886.
X(E):2037240.36 `s
Y(N):823647.07 X
Location -
xv
Degrees -Minutes Seconds
Decimal Degrees Q �1
Decimal Minutes _
I + _ e
5t , Jeri Po
E Knox �a r
i
h`
Nancygt `
c %
Figure 5. Example of location function
2. Length - determines the distance between selected points in feet, kilometers, meters, statute
miles, and yards. A white circle indicates selected points. Figure 6 shows the complete distance, in feet,
between 3 different outfalls.
Length: 3179.02
Length -
Feet - '
Feet
Kilometers - -
Meters
Statute Miles
Yards ,te
\/F. Knox
I Nan" St \
0
y �o Ellerbe Creek
� o-EMarkhamAve
4 �
�.TrinitY \ h 'Q
+„� rC Geet.S
Figure 6. Example of length function between 3 outfalls
3. Area — measures the area of a drawn polygon in acres, hectares, square feet, square miles,
square kilometers, square meters, or square yards. Perimeter of the polygon is measured in feet. Figure
7 shows how the area function can be used to estimate a drainage area for outfall # 28531.
CITY OF DURHAM DRY WEATHER OUTFALL SCREENING OCTOBER 1, 2015 (DRAFT)
STANDARD OPERATING PROCEDURES PAGE 13

Area: 7.42
l �l Perimeter 2251.98
A rc� .
ZPn
216
07 215
8her Creek
2805 2B06 20
L 2803
2801 ,0
2004
2711 2608
2709 A? 2606
12609 2604
2707 , 2605 2602
2705 2601
2706
2703 Fee.,
2704 2521
!701 2519
3
r 101 103 105 1072517 fq`�'•
V~
�yz 2612
2610
Figure 7. Example of Area function
'202 i
120 118
2 ■C}< 115
■ 114
20 ■■
291 2908 t 112
17
2907 ■K 110
2904 111
29 198
03 ■�, 2902 109 C,
"r 2606 107 �_ 10i
kk `z
ato15� 2807 t•� 2806 105 �� 1
r
2805 f 2804
105 103 V ,
2803
■■ 2802 ^
r
2516 1 110
2915
2705 102 104 106
2703
Bookmarks - Bookmarking saves a screen location on the map. The screener can name the view by
selecting the edit pencil. If the screener wants to go back to a saved view then simply click on the
desired bookmark name.
GPS — Used to find the screener's location on the map.
Layers - The layer function will show the screener what layers can be used during screening. The check
mark next to the layer means that it is active. The legend tab shows the symbol associated with each
layer feature. Available layers with their corresponding descriptions and symbology are included in
Appendix E.
CITY OF DURHAM DRY WEATHER OUTFALL SCREENING OCTOBER 1, 2015 (DRAFT)
STANDARD OPERATING PROCEDURES PAGE 14

Outfall Tab
In the outfalls tab you will see the map with all its functions mentioned above. Figure 8 points out the
key functions of the outfall tab.
Select Watershed or
Outfall
Watershed: ALL WATERSHEDS J DutfalM 28230
_c
W—rse.d: rvord�as<ueek
Pj"Ty ;
®
Drop down
ma.:mn: NO
4Addreas
menu of
oi.n,.nr: st
p ieanuh
functions
IE
PC— COMPLM
K Find
Outfall Lwadon: IeW ECOrnwalli5 n4.
%Me um
Information cwm�: Oown:l.ea ftmPor
g Boaksaarks
on he, 00 radon
0 GPS
D.M. Add Sr M.S
layers...
Cvv+slN.cc 5ccc���zs
y
12/1/2014 12:08:4 6 PM
�
Eno River
Screening
r
Options and
Previous
Screenings
Zoom
FM1
Figure 8. A view of the outfall tab.
Watershed- lists all the watersheds in the city's jurisdiction. When a watershed is selected the map will
zoom in to give a closer look at the entire watershed.
Outfall #- lists all the stormwater nodes in the city's jurisdiction. Any stormwater node can be entered
into this box and once entered the map will zoom in to show that feature and information about that
node will be displayed.
SW Node Information- On the left side of the screen, designated information about that feature will be
displayed. This information includes the features watershed, the material in which it's made, the type of
feature it is, its form, status (Proposed, Declined, Complete), general location, and any comments that
have been added about the feature.
Screening Options- If the feature is an outfall the screener has the option to "decline" the outfall if it
doesn't meet the screening criteria. To add a new screening, simply press the "Add Screening" button.
The screening form will pop up. Figure 9 and Table 2, seen on the next page show a blank screening
form, all the physical observation drop down options, and all the in -situ measurement units.
CITY OF DURHAM DRY WEATHER OUTFALL SCREENING OCTOBER 1, 2015 (DRAFT)
STANDARD OPERATING PROCEDURES PAGE 15

Facility ID:
Screenedd: i
Screener2:
Industrial: Non -Industrial
Damage:
Odor:
Obstruction %:
Deposits:
Flow:
Rate Method:
Floatables:
Turbidity:
Comments:
Figure 9. Blank screening form
Screen Date: 5/7/2015 11:31:40 AM
no naensummenr
Temperature: o
Conductivity:0 0
pH: o
DO mg/L: o
DO %: o
Ammonia: 0 0
Chlorine: 0 0
Detergents: o
Copper: 0 n
Phenols:0 0
Contaminated?
Lab Sample?
Save Cancel
Criteria
Drop Down Options/Units
Screener 1 and 2
A list of screener initials
Industrial
Non -industrial, Industrial -Other, Industrial-NPDES
Damage
Concrete Erosion, Cracking/Spalling, Disconnected, Metal Erosion, None,
Other, Outlet Capacity Reached
Odor
Detergent, Fuel/Oil, None, Other, Sewage, Sulfide
Obstruction %
0%, 1-25%, 26-50%, 51-75%, 76-99%, 100%
Deposits
Algae, Oily, None, Other
Flow
Dry, Heavy, Moderate, Pool, Trickle
Rate Method
Visual, Container, No Flow
Turbidity
Clear, Cloudy, No Flow
Temperature
°C
Specific conductivity
µS/cm
pH
DO
mg/L, %
Ammonia
ppm
Chlorine
ppm
Detergents
ppm
Copper
ppm
Phenols
ppm
Contaminated?
Yes, No
Lab Sample?
Yes, No
Comments
Table 2. Options in the digital screening form.
CITY OF DURHAM DRY WEATHER OUTFALL SCREENING OCTOBER 1, 2015 (DRAFT)
STANDARD OPERATING PROCEDURES PAGE 16

Below the "Decline" and "Add Screening" buttons, dates of previous screenings are listed and
information about those screenings can be accessed by double clicking on the date or time. Figure 10
gives an example of a previously completed screening.
7M Add/Edit 0utfd 5c 1,go %%4M 4001�- - e � o I Q-I
Facility ID: 35408
i
Screener 1: TM_
Screener 2:I
AVI_1
Industrial:
Non -industrial_
Damage:
None -
Odor:
None -
Obstruction %:
0% -
Deposits:
None -
Flow:
Pool -
Rate Method:
Visual -
Floatables:
None -
Turbidity:
Clear -
Comments:
Screen Date: 12/2/2014 10:04:04 AM
No Nteos wr nt
Temperature: 10.9 0
Conductivity: 998 0
pH: 7.6 0
DO mg/L: 1.86 0
DO %: 16.8 0
Ammonia:0 0
Chlorine: �
Detergents: 0.25rj
Copper: -Ez
Phenols: -
Contaminated?
Lab Sample? No -
High Conductivity_ Per the SOP, 0-25 on detergents is permissible.
Created: royma on 121212014 10:39:45 AM
Last Edit: royma on 121812014 9:27:12 AM
Figure 10. Example of a completed, digital screening form
Save Cancel
CITY OF DURHAM DRY WEATHER OUTFALL SCREENING OCTOBER 1, 2015 (DRAFT)
STANDARD OPERATING PROCEDURES PAGE 17

Reports Tab
The reports tab contains options for viewing information collected during screening. Figure 11 is a
screen shot of the reports tab showing all the options.
❑utfa,.. _J� Map -1. Reports
All Completed Outfall Screenings
Outfalls by Waterhsed
Completed Outfall Screenings
by watershed:
Declined Outfalls
Figure 11. Screenshot of the reports tab
All Completed Outfall Screenings —
View All
Datasheet
View All
View All
Datasheet
View All
screenings missing drlto Fix These...
View All — This is a basic table that shows the total number of outfalls screened, the total proposed
outfalls, and the percentage of outfalls that have been screened. It lists the screened outfalls, starting
with the most recently screened outfall, and tells the facility ID, screened date, the screeners initials, the
watershed it lies in, and if the outfall was found to be contaminated. Each screening is clickable and the
completed screening form will pop up when selected.
Datasheet — This reveals a more detailed and interactive table that can be filtered and sorted. Data
cannot be edited from this table. This table shows all screening information including screening date,
facility ID, screener initials, the watershed, land use, physical observations, in -situ field measurements,
in -situ indicator field test results, if the outfall is contaminated, if a lab sample was taken, any
comments, and XY coordinates.
Outfalls by Watershed —This option breaks down the percentage of outfalls screened by watershed.
CITY OF DURHAM DRY WEATHER OUTFALL SCREENING OCTOBER 1, 2015 (DRAFT)
STANDARD OPERATING PROCEDURES PAGE 18

Completed Outfall Screenings by Watershed —These options are the same as the All Completed Outfall
Screenings except they can be selected based on watershed. The watershed of interest can be selected
from the drop down menu.
Declined Outfalls — This option gives a list of all declined outfalls. The table shows how many outfalls
have been declined, the facility ID, date it was declined, the screener's initials, and the reason the outfall
was declined. To view any additional comments double click on the entry of interest.
Fix These... - This is a table of screened outfalls that are missing data.
Preparing for Technical Difficulties in the Field
Once the screeners have determined priority areas, maps need to be printed off to use as a reference or
if technical issues arise in the field. The maps should be sufficient enough to locate the days projected
outfalls and to trace the stormwater system of each outfall upstream to at least one stormwater node.
The maps must also include the outfall ID#. A copy of the field screening form can be found in the
Appendix A of this document. Screeners should always have at least 10 of these forms in their
clipboard.
Preparation Prior to Leaving for the Field
One screener is in charge of calibrating the pH/Specific conductivity pen and YSI Pro ODO Meter as per
the Illicit Discharge Detection and Elimination SOP. While calibrations take place the other screener
collects all the necessary supplies, found in Appendix B, and starts loading the vehicle.
Procedure for Screening an Outfall
The staff member that will be performing screening at the outfall should be the one driving to the site.
The passenger should log on to the mobile PC, open the outfall screening database, and find the first
outfall that will be screened. This person may also act as a navigator. This staff member, the recorder,
will remain in the vehicle, prepare to enter information into the Outfall Screening Database, and lead
the screener by asking the information needed to screen an outfall. Two-way radios may be used to
communicate information between the screener at the outfall and the staff member at the vehicle when
necessary. The screener will use their judgment as to decide what is necessary to take down to the
outfall. A backpack with the pH/Specific conductivity pen and ODO meter, and a CHEMetrics kit should
always be taken to the outfall. The sampling pole is a commonly used tool to collect a sample and if
feasible should be taken to the outfall as a time saving practice. Use discretion when necessary as some
outfalls may be difficult to access due to vegetation and terrain. Gloves must be worn when screening
all outfalls and changed between screenings.
Physical Observations
CITY OF DURHAM DRY WEATHER OUTFALL SCREENING OCTOBER 1, 2015 (DRAFT)
STANDARD OPERATING PROCEDURES PAGE 19

Physical observations documented during screening, such as odor, deposits and staining, excessive
vegetation, and floatables, can indicate the presence of an intermittent discharge. Other physical
observations, such as damage to the outfall or excessive obstructions, can be relayed to the appropriate
City staff in the Infrastructure group or Stormwater Maintenance to rectify the problem. When arriving
to the outfall the recorder will start running through the necessary physical observations that need to be
documented in the outfall screening database. Below are the physical observations that need to be
relayed to the recorder:
Damage: concrete erosion, cracking/spalling, disconnected, metal corrosion, outlet capacity reached,
other, or none.
*If other is selected for any category then it must be explained in the comments section of the digital
screening form.
Odor: detergent, fuel/oil, sewage, sulfide, other, or none.
Obstruction %: 0%, 1-25%, 26-50%, 51-75%, 76-99%, and 100%.
Deposits: algae, oily, other, or none.
Flow: Dry, Pool, Trickle, Moderate, Heavy. Table 3 gives a guide to determining flow rates.
Flow Rate
Description
Dry
No flow from outfall and scour pool shows no indication
of an illicit discharge
*If Dry is selected then rate method, floatables, turbidity,
and In -Situ field measurements will auto fill with default
entries
Pool
No flow from outfall but scour pool shows an indication
of a potential illicit discharge. If pool reaches the outfall
and flow can't be determined then screener must trace
the system upstream to the nearest stormwater feature
to see if flow is present. If flow is present upstream then
screening should be moved to that location.
Trickle
Slight discharge that doesn't maintain a constant stream
flow
Moderate
Enough discharge to create a constant stream flow
Heavy
A significant discharge indicative of a piped stream.
Table 3. Description of flow rates
*If an illicit discharge is discovered then a more accurate flow measurement must be taken to estimate
the volume of pollutant discharged. This procedure can be found below in Section 5.2 Procedures for
Sample Collection and Removing the Source of Discharge. The estimate needs to be reported in the
comments section of the database screening form.
Rate Method: Container, No Flow, Visual
Floatables: Foam, Petrol Sheen, Sewage, Other, None
CITY OF DURHAM DRY WEATHER OUTFALL SCREENING OCTOBER 1, 2015 (DRAFT)
STANDARD OPERATING PROCEDURES PAGE 20

Turbidity: Clear, Cloudy, No Flow
In -Situ Field Measurements
In -situ field measurements can indicate pollutant sources. These measurements are made at each
outfall with associated flow or an associated pool. Typical field measurements include temperature,
specific conductivity, pH, and dissolved oxygen. Measurements should be taken directly from water
being discharged from the outfall, or as close as possible so that discharge water is not diluted by the
stream that the outfall is discharging in to. Taking readings from the sampling pole may be necessary
when flow is a trickle or moderate, or if the discharge needs to be pumped from an upstream
stormwater inlet. Any parameter measuring outside of a predetermined acceptable range (see
Appendix C for parameter ranges) will prompt the running of in -situ indicator field tests.
Field Water Analysis Tests
As prompted by field measurements, field water analysis tests (e.g. CHEMetrics Field Test Kits) will be
utilized to identify potential contaminants. Due to the frequency of sewage discharges, ammonia is
measured on all flowing outfalls and outfalls with suspect standing water. Other indicator field tests that
may be employed include phenols, copper, chlorine, and detergents. If the results of any indicator field
test exceeds a trigger level, tracing of the discharge begins.
Tracking Discharges to a Source
If a potential contaminant is identified discharging from an outfall or in standing water associated with
the outfall, tracing the source of contamination commences. Chapter 13 of CWP, 20042 gives
generalized guidance on tracking a discharge to its sources. Strategies include:
• Working progressively up the trunk from the outfall, testing along the way.
• Splitting the trunk into equal segments, testing at strategic locations.
• Targeted investigation, where the evidence (odor, color, screening results) suggest a specific
source
The most appropriate strategy depends upon both the screening results and the size of the pipe
network upstream of the detection location. Where the screening results indicate a particular source
type, targeted investigation may be the most efficient method. For large pipe networks, splitting the
trunk will generally be more efficient. The most commonly used method for smaller networks to work
progressively upstream, as described below.
Investigators will utilize any information that is readily available to them to determine the drainage area
of the outfall. Geographic Information System (GIS) maps of the upstream pipe network can be viewed
on the field PC. The field team will track upstream to the first location where in -situ parameters can be
measured and/or water can be collected for field chemistry analysis. If this location is a point where
more than one pipe enters the drainage system, and both pipes are exhibiting flow, both pipes are
2 Center for Watershed Protection, 2004. Illicit Discharge Detection and Elimination A Guidance Manual for
Program Development and Technical Assessments.
CITY OF DURHAM DRY WEATHER OUTFALL SCREENING OCTOBER 1, 2015 (DRAFT)
STANDARD OPERATING PROCEDURES PAGE 21

tested for the contaminant. Teams will then move upstream in the affected pipe and continue the
method of upstream tracing until the illicit discharge source can be identified. By identifying the first
upstream location where a test for the contaminant is negative, the field team may narrow down the
possible location of the illicit discharge. In some cases, the field team may choose to dye test the
sanitary drains of an adjacent home or business to locate the source of an illicit discharge. If the field
team suspects discharge from a damaged municipal sewer line, the field team can contact a public
works supervisor with the City's Water and Sewer Maintenance Division. If the source cannot be
located, investigators will make notation of the associated land use type (i.e., industrial, commercial,
residential) and return to the office. Additional GIS layers and supporting information can assist in
locating the source of the illicit discharge. In certain scenarios, investigators may be able to immediately
identify probable sources of the illicit discharge based on the contaminant and the land use in the
drainage area of the outfall. This may allow investigators to quickly pinpoint appropriate sampling
locations to identify the illicit discharge source.
Additional investigation methods are discussed in Illicit Discharge Detection and Elimination
Investigations SOG.
Procedures for Sample Collection and Removing the Source of the Discharge
Once an illicit discharge is identified, a water quality investigation file is assigned to the discharge
documenting the investigation history and any associated enforcement actions. Due to the range of
contaminates and discharge sources, the specifics of a water quality investigation will vary slightly;
however, all investigations will follow pre -determined and documented procedure.
Laboratory samples can serve as confirmation of in -situ field test results to calculate spill volume, and
for investigation resolution and enforcement actions. In most cases, water samples will be collected at
the screened outfall/drainage structure (typically the major outfall that was screened) when an illicit
discharge is suspected or detected. The type of samples collected will vary based on results, type of
detection, or suspicion. For example, if a sewage spill or leak is suspected, samples will be collected for
nutrients (ammonia as N, nitrate + nitrite, total Kjeldahl nitrogen, and total phosphorus), 5-day
biochemical oxygen demand (BOD5) and fecal coliform (if the fecal coliform sample can be analyzed by
the lab within the hold time). If an industrial discharge is suspected, collection of metals, total
suspended solids (TSS), or other types of samples may be collected. The screening crew should
coordinate with the outfall screening program coordinator to determine what type of samples that
should be collected.
In addition to sample collection, the flow rate should be estimated and recorded. Along with pollutant
concentrations, flow can be used to estimate spill volume. The two methods that can be employed are
the container method and the visual method. The container method is performed by filling a container
of a known volume with the discharge and timing how long it takes to fill up the container. Flow should
be calculated according to the following equation when using the container method:
(Container Size (gallons) - Time (seconds)) x 60 = Gallons per Minute (gpm)
Example: (5 gallons - 35 seconds) x 60 = 8.57 gpm
In some cases it will be impossible to capture the discharge with a container and the flow and/or spill
volume will have to be estimated with the visual method. The visual method is a visual estimation of
CITY OF DURHAM DRY WEATHER OUTFALL SCREENING OCTOBER 1, 2015 (DRAFT)
STANDARD OPERATING PROCEDURES PAGE 22

the flow and/or spill volume. Because this method is subjective and may be inaccurate, the container
method should be used when possible. The methodology used in determining flow should be
documented in the screener's notes. It is important to note if the flow/discharge appears to be
persistent, intermittent, pulsing, etc.
Discharge tracing and enforcement begins immediately upon detection of a potential illicit discharge
and sample collection, and are not delayed for laboratory results. If or when the source of the illicit
discharge is identified, another set of samples and flow estimates should be collected at the location of
the discharge, or as close to the source as possible to minimize dilution. All samples should be properly
preserved and placed on ice, or stored in the City Hall lab refrigerator until they can be picked up by a
lab courier or dropped off at the designated lab. The submission of any samples to a contract lab must
be approved by the Water Quality Manager, Assistant Water Quality Manager, or Outfall Screening
Program administrator. Each crew performing outfall screening should have a cooler with sufficient wet
ice and 3-4 sample bottles sets prior to departing City Hall each screening day. Samples submitted to a
lab will be accompanied by a Chain of Custody (COC).
Procedure dictates that the discharge is tracked to its source, and a responsible party is identified (See
Appendix I, guidelines for approaching an individual with a NOV). A Notice of Violation (NOV) or Notice
of Requirement (NOR) is issued to the responsible party outlining appropriate Stormwater Management
and Pollution Control Ordinance violations (Article V of the Durham City Code of Ordinances). The
NOV/NOR also outlines remedial actions that need to be taken, and any applicable civil penalties that
apply to the citied violations. Enforcement of indicated remedial actions follows procedure outlined in
Stormwater Management and Pollution Control Ordinance (Section 70, Article V, Durham City Code of
Ordinances).
Quality Assurance
On a monthly basis, the number of outfalls screened, dry versus wet outfalls, illicit discharges, and hours
of field work per team are recorded and reported to program supervisors. Quality analysis/quality
control (QA/QC) measures are performed on a minimum of 10% of field data on a weekly basis. At the
conclusion of each outfall screening season, a memo is prepared that summarizes the extent of City
outfalls screened, conditions under which they were screened, and other applicable statistics from the
season. The memo also outlines any procedural changes from the previous year and provides
suggestions for improving efficiency.
References
Center for Watershed Protection and Robert Pitt. 2004. Illicit Discharge Detection and Elimination A
Guidance Manual for Program Development and Technical Assessments.
CITY OF DURHAM DRY WEATHER OUTFALL SCREENING OCTOBER 1, 2015 (DRAFT)
STANDARD OPERATING PROCEDURES PAGE 23

APPENDIX A: Backup Field Form for Dry Weather Outfall Screening
Facility ID
Tea m
Date
Time
Flow
Dry Trickle Pool Moderate Heavy
Rate Method
No Flow Visual
Container
Odor
None Sewage Detergents
Other:
Oil/Fuel Sulfide
Floatables
None Petrol Sheen Foam
Sewage Other:
Deposits
None Algae Oily Other:
Turbidity
Clear Cloudy
No Flow
Damage
Obstruction (%)
Water Temp
pH
Specific Conductivity
D.O. (mg/L)
D.O. (%)
Ammonia
Chlorine
Detergents
Copper
Phenols
Contaminated
Yes No
Maybe
Revisit
Yes
No
Investigate
Yes
No
Lab Sample
Yes
No
Contact Infrastructure?
Yes
No
Comments
K:\Division Files\Quality\Docs\Outfall Screening\Outfall Field Sheet
Edited by DR on 11/14/2014
CITY OF DURHAM DRY WEATHER OUTFALL SCREENING OCTOBER 1, 2015 (DRAFT)
STANDARD OPERATING PROCEDURES PAGE 24

APPENDIX B: Typical Equipment and Supplies Used During Dry Weather
Outfall Screening
Dry Weather Outfall Screening Checklist
1. Tablet PC
2. Two-way radios
3. Keyboard
4. Jet Pack
5. Car charger
6. YSI ODO & specific conductivity/pH pen
7. Extra Batteries (2 C's and 4 button batteries)
8. Peristaltic pump & battery
9. 20 ft. tubing with weight
10. Sampling pole
11. Stocked CHEMetrics kit
12. Container for estimating flow
13. Sample bottles (nutrient, metal, fecal coliform)
14. Cooler with ice/temp blank
15. Chain of custody
16. Box of Nitrile gloves
17. Tracing dye
18. Spotlight
19. Screwdriver
20. Safety vest/shoes
21. Clipboard with maps and investigation forms
22. Camera
23. Manhole hooks (should be in vehicle)
24. Safety cones (should be in vehicle)
CITY OF DURHAM DRY WEATHER OUTFALL SCREENING OCTOBER 1, 2015 (DRAFT)
STANDARD OPERATING PROCEDURES PAGE 25

APPENDIX C: Flow Chart for Dry Weather Outfall Screening
DRY
INDICATIONS OF AN
INTERMITTENT
DISCHARGE (STAINING,
EXCESSIVE VEGETATION,
FLOATABLE, ODOR)?
YES
NO
LOCATE OUTFALL
OPEN DATABASE ON FIELD PC (OR
FIELD FORMSAS APPLICABLE) AND
BEGIN SCREENING PROCESS
FLOWING
WATER
STANDING
WATER (POOL)
MEASURE TEMPERATURE, CONDUCTIVITY, pH,
DISSOLVED OXYGEN, AMMONIA
• Is TEMPERATURE >35' C?
• Is CONDUCTIVITY >1,100 µS?
• Is 6.0 < pH > 8.5?
• IsAMMONIA>1 mg/L?*
ENTER
APPLICABLE
INFO;
PROCEED TO
NEXT 0UTFALL
YES TO ANY
PARAMETER
TEST WITH ALL
FIELD WATER
ANALYSIS TEST KITS
NO TO ALL
PARAMETERS
INDICATIONS OF AN
INTERMITTENT
DISCHARGE (STAINING,
EXCESSIVE VEGETATION,
FLOATABLE, ODOR)?
YES
NO
\l/ ENTER
BEGIN WATER QUALITY INVESTIGATION; APPLICABLE
TRACK SOURCE OF DISCHARGE INFO;
PROCEED TO
NEXT 0UTFALL
*Ammonia can naturally occur in pools with decaying plant matter at concentrations a1 mg/L.
CITY OF DURHAM DRY WEATHER OUTFALL SCREENING OCTOBER 1, 2015 (DRAFT)
STANDARD OPERATING PROCEDURES PAGE 26

APPENDIX D: CHEMetrics Methods
To avoid contamination and certain health risks it is recommended that
protective gloves be worn during sample collection and analysis. Never
collect a sample by hand in any situation where you must enter an area in
which toxic gasses could pool, or where you must bring your face near an
outfall pipe that could be emitting hazardous or toxic gasses! I Water
Quality staff are not permitted to enter confined spaces under any
circumstance.
a. Ammonia analysis:
1. Rinse the sample cup as follows:
a) Fill the sample cup with the liquid from the sample bottle.
b) Swish the liquid in the sample cup so that all of the interior area has been covered.
c) Discard the rinse liquid downstream of the sampling site.
d) Repeat steps a-c three times
2. Fill sample cup to the 25 ml mark with the liquid from the outfall.
3. Add 2 drops of the A-1500 Stabilizer Solution to the sample liquid in the sample cup.
4. Stir the liquid with the tip of the ampoule.
5. Snap the tip of the ampoule by placing the ampoule tip into one of the depressions in the bottom of
the sample cup, and pressing the ampoule toward the side of the cup. (The sample will fill the ampoule,
leaving a small bubble to facilitate mixing.)
6. Remove the fluid filled CHEMetrics ampoule from the sample cup.
7. Invert the ampoule 3-4 times (or until contents of ampoule appears mixed), allowing the bubble to
travel from end to end each time.
8. Wipe all liquid from the exterior of the ampoule with a paper towel and wait 1 minute.
9. Compare ampoule color to the appropriate color, using either the low concentration tube comparer,
or the mid -to -high range comparer. Identify the comparer concentration color that most closely
matches the ampoule.
10. Discard of the used ampoule in the waste CHEMetrics bottle (white top) marked "Ammonia" or
"NH3".
b. Chlorine analysis:
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1. Rinse the sample cup as follows:
a) Fill the sample cup with the liquid from the sample bottle.
b) Swish the liquid in the sample cup so that all of the interior area has been covered.
c) Discard the rinse liquid downstream of the sampling site.
d) Repeat steps a-c three times
2. Fill sample cup to the 25 ml mark with the liquid from the outfall.
3. Add 5 drops of the A-2500 Stabilizer Solution to the sample liquid in the sample cup.
4. Stir the liquid with the tip of the ampoule.
5. Snap the tip of the ampoule by placing the ampoule tip into one of the depressions in the bottom of
the sample cup, and pressing the ampoule toward the side of the cup. (The sample will fill the ampoule,
leaving a small bubble to facilitate mixing.)
6. Remove the fluid filled CHEMetrics ampoule from the sample cup.
7. Invert the ampoule 3-4 times (or until contents of ampoule appears mixed), allowing the bubble to
travel from end to end each time.
8. Wipe all liquid from the exterior of the ampoule with a paper towel and wait 1 minute.
9. Compare ampoule color to the appropriate color, using either the low concentration tube comparer,
or the mid -to -high range comparer. Identify the comparer concentration color that most closely
matches the ampoule.
10. Discard of the used ampoule in the waste CHEMetrics bottle (white top) marked "Chlorine" or "Cl".
c. Phenols and Copper analysis:
(procedure is the some for both indicators, use appropriate ampoule where appropriate)
1. Rinse the sample cup as follows:
a) Fill the sample cup with the liquid from the sample bottle.
b) Swish the liquid in the sample cup so that all of the interior area has been covered.
c) Discard the rinse liquid downstream of the sampling site.
d) Repeat steps a-c three times
2. Fill sample cup to the 25 ml mark with the liquid from the outfall.
3. Stir the liquid with the tip of the ampoule.
4. Snap the tip of the ampoule by placing the ampoule tip into one of the depressions in the bottom of
the sample cup, and pressing the ampoule toward the side of the cup. (The sample will fill the ampoule,
leaving a small bubble to facilitate mixing.)
5. Remove the fluid filled CHEMetrics ampoule from the sample cup.
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6. Invert the ampoule 3-4 times (or until contents of ampoule appears mixed), allowing the bubble to
travel from end to end each time.
7. Wipe all liquid from the exterior of the ampoule with a paper towel and wait 1 minute.
9. Compare ampoule color to the appropriate color, using either the low concentration tube comparer,
or the mid -to -high range comparer. Identify the comparer concentration color that most closely
matches the ampoule.
10. Discard of the used ampoule in the waste CHEMetrics bottle (white top) marked "Phenols",
"Copper", or "Cu".
d. Detergent Analysis:
1. Rinse the reaction tube with sample, and then fill it to the 5 mL mark with sample.
2. While holding the double tipped ampoule in a vertical position, snap the upper tip using the tip
breaking tool.
3. Invert the ampoule and position the open end over the reaction tube. Snap the upper tip and allow
the contents to drain into the reaction tube.
4. Cap the reaction tube and shake it vigorously for 30 seconds. Allow the tube to stand undisturbed for
about one (1) minute.
2. Make sure the flexible tubing is firmly attached to the CHEMetrics ampoule tip.
6. Insert the CHEMetrics ampoule into the reaction tube making sure that the end of the flexible tubing
is at the bottom of the tube. Break the tip by pressing against the side of the tube. The ampoule should
draw in fluid only from the organic phase (bottom layer).
7. When filling is complete, remove the assembly from the reaction.
8. Wipe all liquid from the exterior of the ampoule. Place ampoule cap firmly onto the tip. Invert the
ampoule several times, allowing the bubble to travel from end to end each time.
9. Place the ampoule, flat end downward into the center of the comparator. Direct the comparator up
toward a source of bright light. Rotate the comparator until you find the color standard that shows the
closest match. If the color is between two color standards an estimate can be made.
10. Discard of the used ampoule and liquid waste in the waste CHEMetrics bottle marked "detergents".
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APPENDIX E: Interpreting Field Results - Observations, CHEMetrics
Results and Physical Measurements
a. Visual Observation
Visual observation can be very effective at detecting higher levels of contamination.
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.
i
sign
• • •
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 of 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.
Ditch excavated to drain
water
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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 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. Color is usually orangish-red to light brown. Iron oxide is formed as the
bacteria converts ferrous iron to ferric iron when it is exposed to air and water. It is the oxidation of
ferrous to ferric that produces the energy needed for the bacteria to survive.
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 taking a stick and running it through
the film. If the film breaks apart, it is from iron bacteria; if it quickly spreads to recover the water, it is
oil.
b. Odor
Odor can also be effective in detecting certain types of illicit discharges. Examples from past
investigations in Durham include a lemon -lime odor (and low pH) traced to a broken pipe at a bottling
plant, and odor traced to an apple cider production facility. Most people can sense odors at very low
concentrations in air.
Petroleum odor in a stormwater pipe may indicate an underground plume entering the pipe, leaking
heating oil tank, spill, etc. Gasoline odors in confined spaces such as pipes should be considered
hazardous. Move to a safe distance and contact your supervisor and HazMat.
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, and the other
compound already mentioned, 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. Many thiols (sometimes referred to as mercaptans in older literature) have strong odors and
can be detected by the human nose at the parts per billion level. As a result of the various compounds
associated with sewage, its distinctive odor can be detected at very low concentrations.
Sewage odors may indicate an illicit discharge such as an SSO, but sewage odors also come from air
escaping from sewer manholes. It is usually fairly 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 the wrong lid.
Incorrect labeling may be obvious when working in sewer easements, but in other locations, the
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manhole labeling may not be reliable. Investigators can use GIS resources to confirm the system for a
manhole.
Once 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.
c. Ammonia (nitrogen)
The City of Durham has used ammonia as a water quality screening parameters since 1999. During that
period, ammonia has been the best single indicator used for finding illicit discharges in dry weather
flows.
Ammonia can converted to other forms of nitrogen. As a consequence ammonia is best used to screen
flows relatively near a source. Once water enters a stream, ammonia generally loses its utility as an
indicator. For general screening ideally outfalls should drain an area of 50 acres or less. In areas
suspected to have illicit discharges, a much smaller drainage area should be used, often 20 acres or less.
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 of 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 as a result 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. An informal experiment where leaves were placed in a jar of
rainwater, capped to simulate stagnant water, and allowed to stand for two weeks, resulted in noxious
odors and ammonia concentrations much greater than 10 mg/I, the upper limits of the test kit. 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.
TOXICITY AND BENCHMARKS - Excessive ammonia concentrations are toxic to aquatic life. In aqueous
solution, most of the ammonia ionizes to ammonium ions, NH4+. Toxicity is mostly due to the un-ionized
fraction. The percentage of total ammonia in solution that is un-ionized increases with increasing pH and
increasing temperature, as indicated in Standard Methods. 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. At one time, North Carolina used in -stream criteria (BAT) applied to
small wastewater discharges of 2.0 mg/L ammonia in summer and 4.0 mg/L in winter, whereas larger
discharges had 1.0 and 1.8 mg/I for summer and winter ammonia limits, respectively as ambient stream
concentration limits.
As indicated in the flow chart in Appendix C, the City of Durham 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 Durham's extensive tree canopy and potential for encountering
leaf -produced ammonia. The appropriateness of this limit may also be influenced by Durham's Triassic
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soils, the low permeability of which limits the flow of groundwater into stormwater pipes from seasonal
high water table.
Herrera (2012) recommended 1 mg/L as a threshold in a review of practices in the Pacific Northwest.
The Center for Watershed Protection (CWP) initially recommended a threshold of 1 mg/L but in more
recent guidance has suggested a lower threshold of 0.3 mg/L to avoid missing sources. This revised
recommendation appears to be based on experience in Baltimore, which has less tree canopy, outfalls
serving larger areas, and greater issues with groundwater infiltration and exfiltration due to more
permeable soils. Durham does not use this lower limit due to false positive results. In those instances
where there is reason to believe a catchment or area has unidentified sources (e.g. based on monitoring
results), smaller drainage areas should be sampled and screened (e.g. sampling within piping networks.)
Based on storm event monitoring conducted in the 1990s, Durham's stormwater runoff typically
averages 0.1 mg/L to 0.6 mg/L of ammonia (all individual measurements were below 1.5 mg/Q.
Durham's selection of 1 mg/L threshold provides sufficient sensitivity to account for dilution and some
loss of ammonia in piping systems. Assuming raw sewage has an average of 50 mg/L ammonia -nitrogen,
the 1 mg/L threshold allows for dilution with groundwater, and some dissipation via oxidation or
volatilization while maintain adequate sensitivity, and reducing false positives from decaying vegetation.
d. 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. Durham'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, the City 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. (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).
e. Detergents (anionic surfactants)
Laundry detergents, household cleaning products and cleaning operations are sources of detergents.
Laundry and cleaning wash water are properly disposed to the sanitary sewer system (or similar).
Consequently, detergents are commonly found in wastewater. In the early days of IDDE programs,
detergents were the principle indicator of sewage, but this function has largely been supplanted by
ammonia.
Laundry detergents typically contain optical brighteners. Some IDDE programs have used optical
brighteners as an indicator. Stormwater Services performed a study assessing field samples that
compared optical brighteners to ammonia. Ammonia was found to be more sensitive and reliable.
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The detergent test is subject to false positive results. In the absence of other indicators, values of 0.25
mg/L or lower should not be considered as triggering an investigation. Detergent test results below 0.25
mg/L should be investigated based on weight of the evidence if color, odor, or other indicators are
present.
f. Copper (total soluble)
Copper is found naturally in the earth's crust and in seawater. Although excessive concentrations of
copper are harmful to human health, copper is an essential trace mineral that is present in all body
tissues, is available as a dietary supplement, and is included in some multivitamins. To minimize
excessive exposure, EPA has established the Maximum Contaminant Level Goal for copper as 1.3 mg/L in
drinking water. By contrast, trout and many other cold water fish species are extremely sensitive to
toxicity from dissolved copper ions. North Carolina has established a water quality standard for
dissolved copper that is dependent upon hardness. For fresh water with a hardness of 25 mg/L as
CaCO3, the dissolved copper acute standard is 3.6 µg/L and the chronic standard is 2.7 µg/L. Water that
is acceptable for drinking can be toxic to sensitive fish species.
Aquatic life toxicity of copper is mitigated when the hardness is higher because gill membranes
preferentially attract divalent calcium and magnesium ions, rather than monovalent copper ions. First
order streams in Durham are fed by groundwater which typically increases the hardness.
Besides being a naturally occurring element, copper is also an important component of fungicides and
insecticides. Copper -containing algaecides have historically been used to control biological growth in
lakes. Copper is added to asphalt roofing shingles to make them resistant to algae and mildew. Copper
panels are occasionally used as a commercial roofing material, and copper has other architectural uses.
The measurement of copper is an important means of monitoring the corrosion of condensate systems
and heat exchangers. Copper is one of the materials used in brake pads. There is a nationwide initiative
to remove copper from brake pads because pad wear is a source of copper.
SCM Metals is an industrial site that reports releases of copper under include There are industrial sites
in Durham that are known to be sources of copper.
g. Phenols
Phenol (hydroxy-benzene) is the simplest of a group of similar organic chemicals which includes: cresols,
xylenols and catechols. Many of these "phenolics" are used as raw materials in the manufacture of
polymers, plasticizers, hydraulic fluids and various industrial chemicals. Phenol itself is a common
ingredient in disinfectants. In drinking water, low-level phenolic concentrations impart a foul taste and
odor, especially upon chlorination. High phenol concentrations can indicate contamination from
industrial effluents or waste discharge.
h. pH
Measurement of pH is one of the most frequently used tests in water chemistry. 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,
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and elevated pH in the range of 8.5 to 9 in combination with warm water significantly increases the
toxicity of ammonia.
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 in marshy areas associated with peat may have pH as low as 4.0. Water passing through decaying
vegetation, including water high in tannins, will have low pH.
High concentrations of carbon dioxide dissolved in water reduces pH. Water bodies that are eutrophic
may undergo diurnal swings in COZ concentration due to net uptake in daylight (photosynthesis) and net
production at night (respiration). The changing concentrations in COZ will produce an accompanying
variation in pH.
pH of common some products:
Battery acid (H2SO4) 1.0
Lemon juice 2.0
Vinegar 2.2
Cola and sodas 2.3 to 3.5
Orange juice 3.0 to 4.3
Baking soda 8.3
Ammonia solution 11
Lime 12
Bleach 13
Drain cleaner 14
While rarely seen outside normal ranges pH has played an important role in several situations. Some
years ago, low pH and citrus smell were initial indicators related to two incidents determined to be a
sewer line leak and a sewer pumping station failure at a soda bottling plant in Durham. In another case,
an industrial site was addressing leaks in underground piping by adding ammonia hydroxide to adjust pH
prior to discharge.
i. 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 C. Specific conductivity is an important water -quality measurement because it gives an idea
of the amount of dissolved material in the water. 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. Seawater has a known composition, making it possible to
convert from one measure to another. Often for freshwater the conversion is done assuming that the
solid is sodium chloride, with a conversion factor of 0.64.
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Specific conductivity is measured microsiemens per centimeter (µs/cm). Distilled water has a specific
conductivity range of 0.5 to 3 µs/cm. The specific conductivity of streams in Durham varies. Lower
values typically occur during wetter periods, which is usually winter and spring in Durham.
Rainwater, being slightly acidic, tends to dissolved minerals as is it passes of 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. If a community is using source water — like well water - that is already high in
dissolved solids, then wastewater will typically have a distinctively high concentration that is readily
distinguishable from groundwater. Conductivity is particularly useful in communities that use well water
as a drinking water source. It has somewhat more limited use in communities like Durham that use
surface waters for water supply.
According to the City of Durham's Water Quality Report for drinking water, average conductivity is 227
µS/cm. (Note: S = mhos), or roughly 145 mg/L TDS. If domestic use of this water adds between 100 and
300 mg/L, the final wastewater would have between 245 and 445 mg/L TDS. Specific conductance for
this range is 380 to 700.
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.
j. Dissolved Oxygen (DO)
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 deg -Celsius can hold about half as much dissolved oxygen as water at 1 deg -
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. Similar to pH, high
concentrations of algae can lead to swings in dissolved oxygen. This is because at night, DO is consumed
and COz 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
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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.
k. Temperature
Temperature is very important to water chemistry because it 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 document 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.
i. Additional Information to Assist interpreting Water Quality Findings.
The two most common discharges in the City of Durham are those involving potable water and those
involving wastewater. However, many other types of discharges have been found since program
inception in about 1997.
Appendix E of CWP (2007) provides reference concentration data for samples collected from a range
water sources from cities in Alabama. Results are provided for tap water samples, spring water, car
wash water, laundry wash water, sewage, and a range of industrial sources (plating bath wastes,
radiator wastes, commercial laundry. It should be noted that some of the sources had elevated
concentrations of fecal indicator bacteria. The samples we not evaluated at high enough concentrations
to assess whether the discharges include sewage. Chapter X of CWP (2007) recommends that IDDE
programs conduct similar characterization for the most common sources. Appendix E tables can may
provide helpful information as to likely source when tracking a discharge with an unusual signature.
The 2014 annual report the City produced as required by the federal Safe Drinking Water Act
summarizes results of potable water monitoring. The report includes the following results:
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Unit
Range
pH
7.5 — 7.6
Conductivity
micromhos/cm
227
Hardness (calculated)
mg/L
21
Fluoride
mg/L
0.70 -0.75
Nitrate
mg/L
<0.10 — 0.40
Total Organic Carbon,
source water
mg/L
5.46 — 8.77
Total Organic Carbon,
treated water
mg/L
1.66 — 2.54
Zinc
mg/L
0.59
Orthophosphate (as PO4)
mg/L
1.68
Chlorine
mg/L
2.0
Potassium
mg/L
2.2
Sodium
mg/L
24.2 - -42.1
Sulfate
mg/L
48 — 69
A sample collected from tap water in the Stormwater calibration lab found similar results.
Concentrations in Tap Water Sample Collected at Stormwater Services
Calibration Lab
Calcium
6,470 µg/L
Copper (Total)
112 µg/L
Iron (Total)
88 µg/L
Lab
Magnesium (Total)
2,480 µg/L
Parameters
Manganese (Total)
18 µg/L
Sodium
34,700 µg/L
Zinc (Total)
1,140 µg/L
Hardness (calculated)
26 mg/L
Note: The field screening kits used in outfall screening report results in milligrams per liter. The tap
water sample results for copper would be 0.112 mg/L. This concentration would barely register on a test
range of 0.1 to 10 mg/L.
Raw domestic sewage varies in strength depending upon various factors that influence dilution, such as
infiltration -inflow (1&1). Minerals concentrations tend to reflect those in potable water plus a range of
added mineral. Metcalf and Eddy (1991), a standard wastewater engineering text provides typical
composition for weak, medium and strong concentrations for preliminary planning purposes.
Typical Domestic Wastewater
Parameter I Unit Weak Medium Strong
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BOD,S
mg/L
110
220
400
Total Organic
Carbon
mg/L
80
160
290
Organic nitrogen
mg/L
8
15
35
Ammonia nitrogen
mg/L
12
25
50
Total nitrogen
20
40
85
Phosphorus (total)
mg/L
4
8
15
Estimated Range of Minerals in Watewater
City of
Typical Mineral
Durham
Range Expected in
Increase
Pota
ota
Potable
Domestic
(Metcalf & Eddy, 1999)
Wastewater
Parameter
Calcium mg/L
6 — 16
6.5
12 — 22
Magnesium mg/L
4 —10
2.5
6 —13
Potassium mg/L
7-15
2.2
9 —17
Sodium mg/L
40 — 70
35
75 - 105
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APPENDIX F: CHEMetrics Waste Disposal and Segregation
CHEMetrics test kits for field analytical measurements contain disposable ampoules, some which are
hazardous in nature. The use of CHEMetrics test kits generate waste which must be properly segregated
and disposed. It is the responsibility of all City of Durham Stormwater & GIS Services Division staff that
use CHEMetrics test kits to follow the proper procedures for segregation and disposal of these wastes.
Based upon information contained within the individual CHEMetrics material safety data sheets (MSDS),
CHEMetrics wastes generated by the City of Durham Stormwater & GIS Services Division staff shall be
segregated into 6 separate waste groups as follows:
CHEMetrics Waste Group 1 (Container # 1)
Name
Catalog #
pH
Incompatibilities
Known Hazards
Strong Acid
Phosphate
Strong Bases
Hazardous Decomposition
R 8510D
0.5
Products
Ampoule
Heat
Soluble molybdenum
compound (Carcinogen)
Strong Acid
Reducing materials
Chromate
Hazardous Decomposition
Acidifier
A2800
0.5
Bases
Products
Solution
Metals
CHEMetrics Waste Group 2 (Container # 2)
Name
Catalog #
pH
Incompatibilities
Known Hazards
Caustic
Ammonia
Strong Acids
Mercury compound
R1501
13.5
Ampoule
Oxidizers
Hazardous
Decomposition
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Products
CHEMetrics Waste Group 3 (Container # 3)
Name
Catalog #
pH
Incompatibilities
Known Hazards
Ammonia
Stabilizer Solution
A-1500
8
None
None
Chlorine
Hazardous
Neutralizer
A-2501
7.7
Heat
Decomposition
Products
Solution
Chlorine
Hazardous
R-2500
6.3
Heat
Decomposition
Ampoule
Products
Formaldehyde
(Carcinogen)
Chlorine
R-2505
4
Heat
Hazardous
Ampoule
Decomposition
Products
Copper
Hazardous
R-3510
7
Heat
Decomposition
Ampoule
Products.
CHEMetrics Waste Group 4 (Container # 4)
Catalog
Name
pH
Incompatibilities
Known Hazards
Strong Bases, Metals,
Flammable, Hazardous
Detergents
Decomposition,
R-9400
Strong Oxidants, Heat
Chloroform (Carcinogen)
Ampoule
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CHEMetrics Waste Group 5 (Container # 5)
Name
Catalog
pH
Incompatibilities
Known Hazards
Strong Acids
Phenols
Hazardous
R-8012
10.7
Ammonia
Decomposition
Ampoule
Products
Heat
Chlorine
Hazardous
Activator
A-2500
11
Heat
Decomposition
Products
Solution
Note: Never store unlike CHEMetrics waste products (ampoules & solutions) together other than
described above. Dangerous reactions may occur if these waste products are improperly segregated.
Requirement of proper waste containers
Once an ampoule is used, it becomes waste and must be properly disposed of. Each City of Durham
Stormwater & GIS Services Division vehicle that possesses a CHEMetrics test kit of any kind must also
keep a properly labeled waste container (250 mL polypropylene bottle) for each type of waste category
(shown above) in order to ensure that CHEMetrics wastes are properly segregated in the field. A
properly labeled container is defined as such indicating which used CHEMetrics solution wastes can be
stored in them as well as identifying potential hazards of each waste product.
Procedure for proper segregation and disposal (from field to office)
After each individual use, used CHEMetrics solution wastes must be properly segregated and stored into
the appropriate 250 mL polypropylene waste container (based upon the 6 waste groups listed above).
Large CHEMetrics waste containers and 4 mm. thick plastic hazardous material disposal bags are located
in the chemical storage locker in the Stormwater Lab. When each individual 250 mL polypropylene
waste container becomes % full, it is the responsibility of the staff member using that container to:
1) Empty the contents into anew 4 mil thick plastic hazardous material disposal bag
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2) Place the plastic hazardous material disposal bag w/ CHEMetrics waste into the appropriate large (4
gallon HDPE) CHEMetrics waste container (based upon the 6 waste groups listed above). Note: Each
large CHEMetrics waste container is labeled similar to the 250 mL waste containers and identifies which
CHEMetrics and CHEMetrics solution wastes can be stored in them.
3) Place the lid back on the container so that it is tightly secured, return the waste container to the cabinet,
and close the cabinet.
Procedure for proper disposal (from office to Transfer Storage & Disposal Facility)
The chemical waste disposal coordinator will contract with and outside waste disposal company to
ensure chemical waste generated by the City of Durham Stormwater & GIS Services Division is disposed
of in a timely and proper manner.
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APPENDIX G: Exceptions to Prohibited Discharges
While NPDES permit NCS000249 requires the City to prohibit most non-stormwater flows from entering
the MS4, it does provide for exceptions. These exceptions include discharges authorized by and in
compliance with a valid NPDES permit. Control of the impact of permitted discharges should be
accomplished through appropriate discharge limits, conditions, and provisions in the permit.
The City's NPDES permit also exempts discharges determined to be incidental non-stormwater flows
that do not significantly impact water quality, and lists a number of examples which are conditionally
allowed, provided they are not determined to have a significant impact:
Dechlorinated water line flushing; landscape irrigation; uncontaminated groundwater infiltration and
pumped groundwater; minor discharges from potable water sources; air conditioning condensate
(commercial/residential); irrigation waters (does not include reclaimed water as described in 15A NCAC
2H .0200); lawn watering; residential and charity car washing; dechlorinated swimming pool discharges;
street wash water; flows from emergency firefighting.
Exceptions for the above examples are conditional on the discharge not having a significant impact on
water quality. In the past, all discharges of potable water were considered not to have a significant
impact. At that time the City used free chlorine in potable water to provide a disinfectant residual to
keep pathogenic organisms from reproducing in the distribution system. Free chlorine dissipates fairly
quickly in the environment. Following the City's switch from free chlorine to chloramines as a
distribution system disinfectant, specific instances were found where large or persistent discharges of
potable water were found to impact water quality. Chloramines are less reactive than free chlorine, and
as a result they are four to ten times more persistent. Chloramines are also less effective as a
disinfectant, and thus, dosage may need to be increased. The change in persistence (possibly combined
with adjustments in dosage) that accompanied the switch to chloramines required treating potable
water more cautiously. During hydrant flushing operation, the City's Water Management Department
now uses diffusers that contain dechlorinating agents (Vita-C is one type) to remove most of the
chloramines. Currently minor discharges of potable water - typically small amounts not discharged on a
regular or continuous basis - continue to be exempted.
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APPENDIX H: GIS Symbology for the Outfall Screening Database
GIS Layers, Symbology and Descriptions
Layer
Description
Symbol
Outfall
Contaminated (Maybe)
Contaminated (Yes)
Proposed
Screened
Declined
X
No Pipe Diameter
SCMs/BMPs
Bioretention Area
Cistern
Constructed Wetland
Dry Pond
Fil Terra
Level Spreader
Pocket Wetland
Sand Filter
Underground Storage
Unclassified
Wet Pond
Stormwater Drains
Clean Out
Combination Inlet
■
Curb Inlet
■
Drop Inlet
■
End Section
Headwall
A
Junction Box
■
Manhole
Other
■
Possible Junction
?
Riser Pipe
Slab Inlet
Unclassified
F]
Weir Box
Minor (Exterior Drain)
■
Minor (Interior Drain)
Minor (Roof Drain)
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GIS Layers, Symbology and Descriptions
Layer
Description
Symbol
Stormwater Pipes
Private/Pending
City; City Right of Way
>
Stormwater Channels
Ditch/Flowline
- -
River
—
Stream
—
Watersheds
Water Facilities
Water Tank
Pump Station
[ ]
Raw Water Intake
0
Storage Basin
Water Treatment Plant
OR
Water Fittings
Bend
g
Cap
■
Coupling
C
Cross
+
FDC
x
Reducer
Tap
•
Tee
Water Sampling Station
Sampling Station
m
Water Pump
Pump
•
Fire Hydrant
City of Durham
Private/Pending
Others
Water Meter
Meter
Water Valve
Valve
d
Post Indicator Valve
0
Water Control Valve
d
Water Lateral
Transmission Main
Water Mains
City of Durham
Private/Pending
Sewer Facilities
Treatment Plant
*T-P
City Lift Station
N
City Pump State
County Pump Station
Private Pump Station
Monitoring Sites
Monitor Site
Q
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GIS Layers, Symbology and Descriptions
Layer
Description
Symbol
Clean Out
City of Durham
Private
Control Valve
Control Valve
Grease Trap
-
Oil/Water Separator
.
Manhole
City of Durham
Private/Others
System Valve
h
Gravity Main
City of Durham
?_
County
Duke
�
Private/Others
Lateral
City of Durham
Private
-
Force Main
City of Durham
s
Private
�
Street Centerlines
City Street
—
Pending City Acceptance
Alley
Future
- -
Private Street
Interstate
US Highway
NC Highway
State Road
—
Ramp
—
Gravel Streets
State Streets
City Maintains
Fire Stations
Public Schools
j
Trails and Greenways
FEMA Flood Zones
1% Future Conditions
El
A
AE
AEFW
AO
Shaded X
Streets
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GIS Layers, Symbology and Descriptions
Layer
Description
Symbol
Railroads
City Boundary
r..
Buildings
Contours
loft
2 ft
City Parks
County Boundaries
L_J
RTP
Parcels (Filled)
Within City
Outside City; 260,• 900
Parcels (Hollow)
City
Not City
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APPENDIX H: Summary of Outfall Screening Results 2008 through 2014
Outfall Inspection Summary Information
Summary information for seasons 2000-2010 through 2013-2014
2009-2010
2010-2011
2011-2012
2012-2013
2013-2014
Winter
Winter
Winter
Winter
Winter
Summer
Primary Watershed(s)
Northeast
Third Fork
Ellerbe
Little Lick,
Sandy, Eno
Various*
Outfall screening period
6 months
2 months
5 months
5 months
4 months
5 Months
Total number. of outfalls visited
275
281
384
244
275
91
Number of outfalls with flow or standing water
40
47
149
104
167
40
Percent (%) of outfalls with flow or standing water
14%
17%
39%
43%
61%
44%
Investigations resulting from outfall screening
1
8
34
6
39
3
Sources eliminated from outfall screening investigations
1
6
26
2
6
3
Percent of flow outfall resulting in investigations
3%
17%
23%
6%
23%
8%
*Little Lick, Lick, New Hope, Mud, and Crooked
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