(SWMP) Stormwater Management Plan - TOWN OF CHAPEL HILL NPDES MS4 Permit #NCS000414
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TOWN OF CHAPEL HILL
Stormwater
Management Plan
(SWMP)
NPDES MS4 Permit #NCS000414
February 2021
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Town of Chapel Hill Stormwater Management Plan
NPDES MS4 Permit #NCS0000414
February 2021
Table of Contents
List of Abbreviations ................................................................................................................................. 6
1 Introduction .......................................................................................................................................... 8
2 Jurisdictional Area ................................................................................................................................. 9
3 Population and Estimated Growth Rate ............................................................................................. 10
3.1 Population ................................................................................................................................... 10
3.2 Growth Rate ................................................................................................................................ 10
4 Stormwater Conveyance System Description..................................................................................... 10
5 Estimated Land Use............................................................................................................................. 11
6 Receiving Streams ............................................................................................................................... 12
7 Impaired Streams and Existing Programs to Address ......................................................................... 13
8 Total Maximum Daily Loads (TMDLs) ................................................................................................. 14
9 Existing Water Quality Programs ........................................................................................................ 15
9.1 Town Land Use, Development, and Stormwater Standards and Plans ...................................... 15
9.1.1 Chapel Hill 2020 Comprehensive Plan ................................................................................ 15
9.1.2 Town of Chapel Hill Public Works Engineering Design Manual .......................................... 15
9.1.3 Stormwater Management Master Plan .............................................................................. 16
9.1.4 Booker Creek Subwatershed Studies .................................................................................. 16
9.2 Town Code of Ordinances ........................................................................................................... 16
9.2.1 Flood Damage Prevention Ordinance ................................................................................. 16
9.2.2 Erosion and Sediment Control ............................................................................................ 17
9.2.3 Illicit Discharge Detection and Elimination (IDDE) .............................................................. 17
9.2.4 Land Use Management Ordinance (LUMO) ........................................................................ 18
10 Partnerships and Inter-local Agreements ........................................................................................... 22
10.1 Orange County Erosion Control .................................................................................................. 23
10.2 Town of Carrboro ........................................................................................................................ 23
10.3 University of North Carolina at Chapel Hill (UNC) ...................................................................... 23
10.4 Orange Water and Sewer Authority (OWASA) ........................................................................... 23
10.5 North Carolina Department of Transportation (NCDOT) ............................................................ 24
10.6 North Carolina Watershed Stewardship Network (NCWSN) ...................................................... 24
10.7 Clean Water Education Partnership (CWEP)............................................................................... 24
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Town of Chapel Hill Stormwater Management Plan
NPDES MS4 Permit #NCS0000414
February 2021
10.8 Nutrient Scientific Advisory Board (NSAB).................................................................................. 24
10.9 Jordan Lake One Water (JLOW) .................................................................................................. 25
10.10 Orange County Hazard Mitigation Plan ...................................................................................... 25
11 State Programs ..................................................................................................................................... 25
12 Reliance on other Government Entity ................................................................................................. 26
12 Points of Contact & Organizational Charts ........................................................................................... 26
13 Public Education and Outreach Program ............................................................................................. 30
13.1 Target Pollutants and Audiences .................................................................................................. 30
13.2 Methods for Education and Outreach .......................................................................................... 31
13.3 Best Management Practices for the Public Education and Outreach Program ............................ 33
14 Public Involvement and Participation Program ................................................................................... 35
14.1 Stormwater Management Utility Advisory Board......................................................................... 35
14.2 Outreach and Volunteer Opportunities ........................................................................................ 35
14.3 Public Involvement in Subwatershed Studies ............................................................................... 36
14.4 Best Management Practices for the Public Involvement and Participation Program .................. 36
15 Illicit Discharge Detection and Elimination (IDDE) ............................................................................... 37
15.1 Storm Sewer System Map ............................................................................................................. 37
15.2 Regulatory Mechanism ................................................................................................................. 40
15.3 Detection and Elimination............................................................................................................. 40
15.4 Enforcement Procedures .............................................................................................................. 41
15.5 Non-Stormwater Discharges With Potential to Significantly Contribute Pollutants .................... 41
15.5.1 Pool Discharge & Backwash ................................................................................................ 42
15.5.2 Commercial Air Conditioning Condensate .......................................................................... 42
15.5.3 Water Line Flushing............................................................................................................. 43
15.5.4 Other Prohibited Discharges ............................................................................................... 43
15.6 Outreach & Education ................................................................................................................... 43
15.7 Staff Training ................................................................................................................................. 43
15.8 Evaluation...................................................................................................................................... 44
15.9 Best Management Practices for Illicit Discharge Detection and Elimination................................ 44
16 Construction Site Runoff ..................................................................................................................... 47
17 Post-Construction Stormwater Program ............................................................................................ 47
17.1 Regulatory Mechanism ............................................................................................................... 48
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Town of Chapel Hill Stormwater Management Plan
NPDES MS4 Permit #NCS0000414
February 2021
17.2 Operation and Maintenance ....................................................................................................... 48
17.3 Best Management Practices for the Post-Construction Stormwater Program .......................... 48
18 Pollution Prevention and Good Housekeeping ................................................................................... 51
18.1 Municipal Facilities Operation and Maintenance Program ........................................................ 52
18.2 Spill Response Program............................................................................................................... 52
18.3 Municipal Storm Sewer System (MS4) Operation and Maintenance Program .......................... 53
18.4 Municipal Stormwater Control Measure (SCM) Operation and Maintenance (O&M) Program 53
18.5 Pesticide, Herbicide and Fertilizer Management Program ......................................................... 54
18.6 Vehicle and Equipment Maintenance Program .......................................................................... 54
18.7 Pavement Management Program............................................................................................... 54
18.8 Employee Training Program........................................................................................................ 54
18.9 Best Management Practices for Pollution Prevention and Good Housekeeping for Municipal
Operations .............................................................................................................................................. 55
19 References .......................................................................................................................................... 59
List of Tables
Table 1. Town of Chapel Hill Population and Growth Statistics, April 1, 2010-July 1, 2019. ...................... 10
Table 2: Land use types by percent area within the Town of Chapel Hill’s zoning jurisdiction.................. 12
Table 3. Water quality classifications, use support ratings, and 303(d) list parameters of interest for
receiving streams within the Town of Chapel Hill's zoning jurisdiction (NCDWR 2018). ........................... 12
Table 4. Minimum tree canopy coverage standards by land use type. ...................................................... 22
Table 5. Primary points of contact for the Town of Chapel Hill's MS4 Permit. .......................................... 26
Table 6. Responsible positions and staff per SWMP component. .............................................................. 29
Table 7. Summary of target pollutants and sources, target audiences, and program(s) to address target
pollutants. ................................................................................................................................................... 30
Table 8. BMPs for the Public Education & Outreach program. .................................................................. 33
Table 9. BMPs for the Public Involvement & Participation program. ......................................................... 37
Table 10. BMPs for the IDDE Program. ....................................................................................................... 44
Table 11. BMPs for the Post-Construction Stormwater program............................................................... 48
Table 12. BMPs for Pollution Prevention & Good Housekeeping for Municipal Operations. .................... 55
List of Figures
Figure 1. Town of Chapel Hill Corporate (MS4) Limits and Zoning Limits as of November 2020. ................ 9
Figure 2. Map of Jordan Lake Watershed Protection District (blue shading) ............................................. 20
Figure 3. Town of Chapel Hill Organizational Chart Overview. ................................................................... 27
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Town of Chapel Hill Stormwater Management Plan
NPDES MS4 Permit #NCS0000414
February 2021
Figure 4. Organizational chart for the Town of Chapel Hill Public Works Department (December 2020). 28
Figure 5. Stormwater outfalls and receiving streams within the Town of Chapel Hill's zoning jurisdiction.
.................................................................................................................................................................... 39
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Town of Chapel Hill Stormwater Management Plan
NPDES MS4 Permit #NCS0000414
February 2021
LIST OF ABBREVIATIONS
Acronym Meaning
BMP Best Management Practices
CHFD Chapel Hill Fire Department
CO Certificate of Occupancy
COVID-19 Coronavirus Disease 2019
CWEP Clean Water Education Partnership
DO Dissolved oxygen
E&SC Erosion and Sediment Control
ETJ Extraterritorial Jurisdiction
FEMA Federal Emergency Management Agency
FLUM Future Land Use Map
FY19 Fiscal Year 2019
FY21 Fiscal Year 2021
GIS Global Information System
HRD Human Resource Development
HVAC Heating, ventilation, and air conditioning
IDDE Illicit Discharge Detection and Elimination
IPM Integrated Pest Management
JLOW Jordan Lake One Water
IR Integrated Report
LUMO Land Use Management Ordinance
MEP Maximum Extent Practicable
mg/l Milligrams per liter
MS4 Municipal Storm Sewer System
NCAC North Carolina Administrative Code
NCDEMLR North Carolina Division of Energy, Mineral, and Land Resources
NCDEQ or DEQ North Carolina Department of Environmental Quality
NCDOT North Carolina Department of Transportation
NCDWR or DWR North Carolina Division of Water Resources, formerly Division of Water Quality
NCWSN North Carolina Watershed Network
NFIP National Flood Insurance Program
NPDES National Pollutant Discharge Elimination System
NSAB Nutrient Scientific Advisory Board
O&M Operations and Maintenance
OWASA Orange Water and Sewer Authority
PPGH Pollution Prevention and Good Housekeeping
RCD Resource Conservation District
SCM Stormwater Control Measure
SOP Standard operating procedure
SWMP Stormwater Management Plan
SWMUAB Stormwater Management Utility Advisory Board
SWPPP Stormwater Pollution Prevention Plan
TJCOG Triangle J Council of Governments
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Town of Chapel Hill Stormwater Management Plan
NPDES MS4 Permit #NCS0000414
February 2021
Acronym Meaning
TMDL Total Maximum Daily Load
TN Total Nitrogen
TOC Town Operations Center
TP Total Phosphorus
TSS Total Suspended Solids
UNC-CH or UNC University of North Carolina at Chapel Hill
USEPA or EPA United States Environmental Protection Agency
USGS United States Geologic Survey
UT Unnamed tributary
Water Quality Classifications
B Primary recreation, fresh water
C Aquatic life, secondary recreation, fresh water
NSW Nutrient Sensitive Waters
WS-IV Water Supply IV - highly developed
WS-V Water Supply V - upstream
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Town of Chapel Hill Stormwater Management Plan
NPDES MS4 Permit #NCS0000414
February 2021
1 INTRODUCTION
The purpose of this Stormwater Management Plan (SWMP) is to provide information for how the Town
of Chapel Hill is complying with the requirements with its National Pollutant Discharge Elimination System
(NPDES) Municipal Separate Storm Sewer System (MS4) Permit and the applicable provisions of the Clean
Water Act to meet the federal standard of reducing pollutants in stormwater runoff to the maximum
extent practicable.
This SWMP identifies the specific elements and minimum measures that the Town of Chapel Hill will
develop, implement, enforce, evaluate, and report to the North Carolina Department of Environmental
Quality (NCDEQ) Division of Energy, Minerals and Land Resources (DEMLR) in order to comply with the
MS4 Permit number NCS000414, as issued by NCDEQ. This permit covers activities associated with the
discharge of stormwater from the MS4 as owned and operated by the Town of Chapel Hill and located
within the corporate limits of the Town of Chapel Hill.
In preparing this SWMP, the Town of Chapel Hill has evaluated its MS4 and the permit requirements to
develop a SWMP that will meet the community’s needs, address local water quality issues, and provide
the minimum measures necessary to comply with the permit. The SWMP will be evaluated and updated
annually to ensure that the elements and minimum measures it contains continue to adequately provide
for permit compliance and the community’s needs.
The six minimum measures the Town is required to address are:
• Public Education and Outreach
• Public Participation and Involvement
• Illicit Discharge Detection and Elimination
• Construction Site Runoff Control
• Post-Construction Runoff Control
• Pollution Prevention and Good Housekeeping for Municipal Operations
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2 JURISDICTIONAL AREA
This SWMP and the MS4 permit applies throughout the corporate limits of the Town of Chapel Hill, and
includes all regulated activities associated with the discharge of stormwater from the MS4.
The current corporate area of the Town of Chapel Hill is 21.5 square miles; the Town’s total zoning
jurisdictional area, which includes the Town’s extraterritorial jurisdiction (ETJ), is 27.5 square miles. The
majority of the Town’s jurisdiction is within Orange County, with a small portion in Durham County.
The map below (Figure 1) shows the corporate and zoning (ETJ) jurisdictional limits of Town of Chapel Hill
as of November 2020. This information can also be viewed on the Town’s Interactive Map online.
Figure 1. Town of Chapel Hill Corporate (MS4) Limits and Zoning Limits as of November 2020.
Page | 9Town of Chapel Hill Stormwater Management Plan
NPDES MS4 Permit #NCS0000414
February 2021
3 POPULATION AND ESTIMATED GROWTH RATE
3.1 POPULATION
There are 63,639 permanent residents within the Town of Chapel Hill’s municipal limits (including
University of North Carolina students), based on July 1, 2019 Certified Estimates with July 1, 2020
Municipal Boundaries (NCOSBM 2019). In addition, during the 2019-2020 school year, 8,183 students
lived on campus of University of North Carolina-Chapel Hill (UNC-CH) and are considered a seasonal
population. As of September 18, 2020, there were only 1,020 students assigned to live on UNC-CH campus
(UNC Housing Office – Carolina Together Dashboard). This change is due to UNC’s effort to de-densify
campus in response to the COVID-19 pandemic.
3.2 GROWTH RATE
The Town of Chapel Hill experienced a total growth rate of 4.8% between 1990 and 2010 (Town of Chapel
Hill 2010); the growth rate was 2.6% per year between 1990 and 2000, and 1.7% per year between 2000
and 2010 (NCOSBN 2016). Forty-two percent of the Town’s population growth between 2000 and 2009
was due to the annexation of urbanized areas (Town of Chapel Hill 2010).
Between 2010 and 2019, the population in Chapel Hill grew by 6,401; the total growth rate during this
time was 11.2%, with 5% of the total growth due to annexation (NCOSBM 2019). See Table 1 for the most
recent population and growth statistics.
Table 1. Town of Chapel Hill Population and Growth Statistics, April 1, 2010-July 1, 2019.
TOWN OF CHAPEL HILL POPULATION AND GROWTH STATISTICS
April 1, 2010-July 1, 2019
Base Estimated
Population Population Change Population
Population Change in Change in Total Percent
April 2010 Annexed Annexed Areas 2010 Limits Change Change July 2019
57233 325 22 6054 6401 11.2 63639
Data Source: NC Office of State Budget and Management, State Demographer
https://www.osbm.nc.gov/demog/municipal-population-estimates
4 STORMWATER CONVEYANCE SYSTEM DESCRIPTION
The Chapel Hill storm sewer system is a combination of open channel and closed channel conveyances.
Stormwater is conveyed to receiving streams by a combination of overland flow, swales and open
channels, curbs, gutters, catch basins, pipes, culverts, ditches, outfalls, and bridges.
As of November 2020, the Town’s Geographic Information System (GIS) includes approximately 120 miles
of streams and open channels, 20 miles of culverts, and 5 miles of ditches within the Town’s corporate
limits. Within the Town’s zoning jurisdiction, there are approximately 155 miles of streams and open
channels, 21 miles of culverts, and 6 miles of ditches mapped.
Page | 10Town of Chapel Hill Stormwater Management Plan
NPDES MS4 Permit #NCS0000414
February 2021
The major receiving streams to which stormwater discharges are conveyed from the Town’s MS4 include
Bolin Creek, Booker Creek, Little Creek, Morgan Creek, and their tributaries within the Cape Fear River
Basin (see Section 6 below). Based on a 2018 update, the Federal Emergency Management Agency
(FEMA)-mapped 1% annual chance floodplains cover approximately 2.3 square miles within the Town’s
zoning jurisdiction. University Place and Eastgate Shopping Center, as well as a number of residences and
other businesses, are within the FEMA-mapped floodplains.
Under average conditions, the Town’s stormwater management systems perform adequately in
containing and conveying stormwater runoff. Localized drainage problems periodically occur in some
locations under certain conditions due to inadequate or deteriorated conveyance facilities and poor
infiltrating soils. During large storm events, culverts and streams in the downstream segments of the
Town’s watersheds periodically flood because of high volumes of runoff in conjunction with low flow
velocity (gradient) in these areas of Town.
The Town’s Stormwater Master Plan (approved by Town Council in 2014) identified as a priority the
continued development of individual subwatershed studies to identify and assess flooding and water
quality issues and develop integrated plans for improvements to the Town’s stormwater conveyance
system. Those studies (and the resulting projects) are ongoing and described further in Section 9 below.
Maintenance and improvements to the MS4 system are funded by stormwater utility fees collected within
the Town corporate limits. The Town’s Stormwater Management Utility was enacted in 2004 and set an
equivalent rate unit fee for impervious surface area. Maintenance of the stormwater system located
within the Town’s rights-of-way and on Town-owned property is performed by seven full-time staff in the
Stormwater Management Division, and includes regular cleanouts of drainage inlets, removal of
blockages, and ongoing repair and upkeep of system components. Maintenance is performed in response
to functional problems using a combination of hand-tools and small power equipment, pressure-flushing,
and/or jet-vacuuming, as appropriate. Street sweeping is also a regular stormwater maintenance activity,
as is seasonal leaf collection. Improvements to the MS4 system include resolving flooding problems
associated with stormwater generated from public streets, stream channel stabilization, stream
restoration, structural Best Management Practices (BMP) installation, and other water quality projects.
The Town contracts with the North Carolina Department of Transportation (NCDOT) for biannual
inspections of some of the bridges/major culvert crossings on Town-maintained streets in Chapel Hill. In
2020, NCDOT was contracted to inspect 19 bridges/major culvert crossings. In addition, Town staff inspect
bridges and road crossings before and after significant storm events, and residents’ reports and
complaints play an important role in identifying stormwater problems.
5 ESTIMATED LAND USE
The estimated percentage of the Town of Chapel Hill’s zoning jurisdiction (including the Town’s municipal
limits and ETJ) that is under residential, commercial, industrial, and open space land use types is shown in
Table 2 below. The percentages for rights-of-way and institutional land uses are also shown. Land use
estimates are derived from 2012 land use data developed by the Chapel Hill Planning Department.
Page | 11Town of Chapel Hill Stormwater Management Plan
NPDES MS4 Permit #NCS0000414
February 2021
Table 2: Land use types by percent area within the Town of Chapel Hill’s zoning jurisdiction.
Estimated Area of
Land Use Type Town’s Jurisdiction
(2012)
Residential 64%
Commercial 4%
Industrial 1%
Open Space 10%
Institutional 16%
Rights-of-Way 5%
Data Source: Chapel Hill 2020 Land Use Plan Map (adopted 2012).
The Town is currently undergoing an update to the Chapel Hill 2020 Land Use Plan Map (adopted in 2012),
as part of a “Charting Our Future” project, which has two phases. The first phase refines the Future Land
Use Map (FLUM), which was originally developed as the Land Use Plan in Chapel Hill 2020, the Town's
Comprehensive Plan. The Town Council adopted the FLUM on December 9, 2020. In 2021, the Town will
proceed with the second phase of the project to rewrite the Town's Land Use Management Ordinance
(LUMO).
6 RECEIVING STREAMS
All receiving streams within the Town of Chapel Hill’s zoning jurisdiction are within the Cape Fear River
Basin and drain to the Morgan Creek and New Hope arms of Jordan Lake. Below is a list of receiving
streams, identified and arranged by stream segment (stream index number). For each stream segment,
the water quality classification, use support rating, and 303(d) list parameters of interest are noted
(NCDWR 2018). For more information on impaired waters and the 303(d) list, including parameters of
interest, see Section 7 below.
Table 3. Water quality classifications, use support ratings, and 303(d) list parameters of interest for receiving streams within the
Town of Chapel Hill's zoning jurisdiction (NCDWR 2018).
303(d) List
Receiving Stream Stream Index Water Quality Use Support Parameter of
Name Number Classification* Rating* Interest*
Little Creek 16-41-1-15-(0.5) WS-IV; NSW Impaired Benthos
Bolin Creek 16-41-1-15-1-
WS-V, C; NSW Impaired Benthos
(Hogan Lake) (0.5)b
Bolin Creek 16-41-1-15-1-(4) WS-IV; NSW Impaired Benthos
Jolly Branch 16-41-1-15-1-2 WS-V; NSW Not Rated n/a
Tanbark (Tanyard)
16-41-1-15-1-3 WS-V; NSW Not Rated n/a
Branch
Booker Creek WS-V,
16-41-1-15-2-(1) Impaired Dissolved Oxygen
(Eastwood Lake) B; NSW
Booker Creek 16-41-1-15-2-(4) WS-V, C; NSW Impaired Benthos
Booker Creek 16-41-1-15-2-(5) WS-IV; NSW Impaired Benthos
Page | 12Town of Chapel Hill Stormwater Management Plan
NPDES MS4 Permit #NCS0000414
February 2021
303(d) List
Receiving Stream Stream Index Water Quality Use Support Parameter of
Name Number Classification* Rating* Interest*
Crow Branch 16-41-1-15-2-2 B; NSW Not Rated n/a
Cedar Fork Creek 16-41-1-15-2-3 WS-V, B; NSW Not Rated n/a
UT at Wright Mobile 16-41-1-15-2-3-
WS-V, B; NSW Not Rated n/a
Homes 1
Old Field Creek 16-41-1-7 WS-V; NSW Not Rated n/a
Morgan Creek 16-41-2-(5.5)a WS-IV; NSW Supporting n/a
Benthos
Morgan Creek 16-41-2-(5.5)b WS-IV; NSW Impaired
Fish Community
Wilson Creek 16-41-2-6 WS-IV; NSW Not Rated n/a
Fan Branch Creek 16-41-2-6-1 WS-IV; NSW Not Rated n/a
Meeting of the Waters 16-41-2-7 WS-IV; NSW Not Rated n/a
Chapel Creek 16-41-2-8 WS-IV; NSW Not Rated n/a
Buck Branch 16-41-2-9 WS-IV; NSW Not Rated n/a
Source to Bolin
Battle Branch C; NSW Not Rated n/a
Creek
*Data Sources: https://deq.nc.gov/about/divisions/water-resources/planning/classification-standards
https://deq.nc.gov/about/divisions/water-resources/planning/modeling-assessment/water-quality-data-assessment
7 IMPAIRED STREAMS AND EXISTING PROGRAMS TO ADDRESS
The assessment of water quality in North Carolina is required under Sections 303(d) and 305(b) of the
Clean Water Act and is to be reported on every two years. This assessment is also known as the Integrated
Report (IR). Impaired waters are a subset of the assessments made where water quality samples for a
particular parameter of a waterbody exceed water quality standards and the assessment methodology
have determined that the waterbody is indeed impaired for the particular parameter. Impaired waters
are grouped into two categories:
• Category 4 assessments are those that do not need a TMDL (Total Maximum Daily Load). These
are not included in the 303(d) list.
• Category 5 assessments are those that require a TMDL or TMDL alternative. These Category 5
waters are assembled in a single document (the 303(d) list) and sent to the USEPA (United States
Environmental Protection Agency) on April 1st of every even-numbered year, per 40 CFR 130.7.
EPA must approve, disapprove, or partially approve each 303(d) list.
Table 3 (above) lists all receiving streams within the Town’s zoning jurisdiction, including information on
streams listed as impaired in the final overall Integrated Report approved by the USEPA (NCDWR 2018).
Of the seven receiving stream segments considered to be impaired, six are impaired for biological
integrity. Biological integrity means the ability of an aquatic ecosystem to support and maintain a balanced
and indigenous community of organisms having species composition, diversity, population densities and
functional organization similar to that of reference conditions (15A NCAC 02B .0202). NCDWR uses a
biological rating method to assess benthic and fish communities for biological integrity.
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February 2021
Booker Creek (Eastwood Lake) is impaired due to low dissolved oxygen (DO). The DO criterion for non-
trout waters is not less than 4.0 mg/l with a daily average of not less than 5.0 mg/l.
Note that though stream segments within the Town’s zoning jurisdiction are designated as impaired
(Category 5), there are currently no TMDL requirements (see Section 8 below).
Chapel Hill addresses impaired waters by implementing the Town’s existing local and state water quality
programs (see Sections 9 & 11 below), interlocal partnerships (Section 10 below), and through activities
associated with the best management practices (BMPs) required in the Town’s MS4 program (see Sections
13-18 below).
The Town also conducts its own annual biological monitoring at several sites located along impaired
stream segments and other receiving waters listed in Table 3. Since 2011, the Town of Chapel Hill has
contracted biological monitoring services with professional benthic macroinvertebrate scientists to
conduct annual water quality monitoring at sites throughout the Town’s jurisdiction. These scientists
include Dave Lenat and Larry Eaton, both of whom previously worked for the NCDWR Biological
Assessment Unit. Town stormwater staff participate in the annual monitoring field work and reporting
and use the results to better understand water quality issues and trends over time within the Town’s
watersheds. All annual reports are provided on the Town’s biological monitoring webpage. As of
monitoring year 2020, the Town is actively monitoring 28 benthic sites annually throughout the Town’s
zoning jurisdiction.
8 TOTAL MAXIMUM DAILY LOADS (TMDLS)
There are no current Total Maximum Daily Load (TMDL) requirements to address water quality
impairments within the Town’s jurisdiction as of the date of this document. However, all of Chapel Hill,
including the Town’s municipal corporate limits and extraterritorial jurisdiction (ETJ), are tributary to the
Upper New Hope Arm of the Jordan Lake (which includes the New Hope Creek and Morgan Creek
tributaries to Jordan Lake).
The North Carolina Division of Water Quality (DWQ, now Division of Water Resources) developed a TMDL
for the B. Everett Jordan Reservoir (Jordan Lake) to address chlorophyll-a impairments, and the EPA
Region 4 approved the TMDL on September 20, 2007. Nutrient controls are the most common focus of
management schemes for reducing excessive algal growth and chlorophyll-a concentrations. Therefore,
the Jordan Lake TMDL was written to address total nitrogen (TN) and total phosphorus (TP) loads to the
lake. North Carolina adopted mandatory Jordan Lake Rules in 2009 to reduce the amount of nutrient
pollution entering Jordan Lake. Implementation of the nutrient reduction regulations has been delayed
by the State Legislature. However, the Town has been complying annually with the Jordan Lake Stage
One Adaptive Management Program for Existing Development Requirements. The Town identifies a
retrofit opportunity for an existing development within the MS4 each year and submits an annual report
to NCDWR.
Two addendums to the Jordan Lake TMDL were later developed and approved: one in 2010 to address
chlorophyll-a impairments in the Haw River (Back Creek and Cane Creek) and Upper New Hope (Morgan
Creek (University Lake) arms; and another in 2014 to address turbidity impairments within the Upper New
Page | 14Town of Chapel Hill Stormwater Management Plan
NPDES MS4 Permit #NCS0000414
February 2021
Hope arm (New Hope and Morgan Creek tributaries), and high pH impairments in the Haw River and Upper
New Hope (Morgan Creek) arms of the lake.
For more information on draft and approved TMDLs within the Cape Fear River Basin, see
https://deq.nc.gov/about/divisions/water-resources/planning/modeling-assessment/tmdls/draft-and-
approved-tmdls#CapeFear.
9 EXISTING WATER QUALITY PROGRAMS
The Town of Chapel Hill implements ordinances, plans, and programs to improve water quality at the local
level, some of which implement state water quality programs. Below are brief descriptions of these
programs, with those that are state programs noted (see also Section 10).
9.1 TOWN LAND USE, DEVELOPMENT, AND STORMWATER STANDARDS AND PLANS
9.1.1 Chapel Hill 2020 Comprehensive Plan
The Town of Chapel Hill adopted the Chapel Hill 2020 Comprehensive Plan on June 25, 2012. The
Chapel Hill 2020 Plan promotes protecting the Town’s natural resources, including stream
corridors, steep slopes, tree canopies, habitat areas, and air and water quality. The 2020 Plan
includes a significant section (Theme 5: Nurturing Our Community) on the protection of natural
resources, particularly calling out protection and improvement of streams and waterbodies, and
management of stormwater. During development of the 2020 Plan, the Town Council endorsed
the initiation of a process for Town staff to review and update the Land Use Management
Ordinance (LUMO), design guidelines, and stormwater regulations (see below for summaries that
include these efforts).
The Town has recently completed an update to the Chapel Hill 2020 Land Use Plan Map (adopted
in 2012), as part of a “Charting Our Future” project, which has two phases. The first phase refines
the Future Land Use Map (FLUM), which was originally developed as the Land Use Plan in Chapel
Hill 2020, the Town's Comprehensive Plan. On December 9, 2020, the Town Council adopted the
Future Land Use Map – Update to Chapel Hill 2020. The second phase of the project will rewrite
the LUMO. For more information, see visit the Charting Our Future website:
https://chartingourfuture.info.
9.1.2 Town of Chapel Hill Public Works Engineering Design Manual
The Town of Chapel Hill Engineering Design Manual provides standards for land development that
are intended to complement and supplement the general Design Guidelines included in the
Town’s 2020 Comprehensive Plan. Specific design criteria set forth within the Design Manual
provide a ready reference of those practices and techniques acceptable to the Town and provides
information on the design and acceptable means and measures to comply with the requirements
of the Town’s Land Use Management Ordinance (LUMO). For example, the Design Manual
provides performance criteria, design standards and details, and guidelines for submission of
stormwater management plans and reports for development and refers specifically to the North
Carolina Stormwater Design Manual. The Town’s Design Manual has been updated, and the draft
is anticipated to be approved by Town Council in 2021.
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February 2021
9.1.3 Stormwater Management Master Plan
The Town of Chapel Hill Stormwater Management Master Plan (Phase I and Phase II) was
developed over a multi-year planning process that established the following key strategic
measures:
• Improve physical, chemical, and biological stream conditions;
• Reduce export of nutrients to Jordan Lake;
• Fewer violations of environmental regulations related to water sources;
• Reduced flooding risk for roads and structures;
• Reduced reactive maintenance activities and repairs;
• More residents, businesses, and staff adopting positive stormwater practices; and
• Benchmarking against best practices among municipal stormwater programs.
Phase I was completed in October 2008, and Phase II was adopted by the Town Council on
September 29, 2014.
9.1.4 Booker Creek Subwatershed Studies
As noted in the Town’s Stormwater Master Plan adopted in September 2014, the development of
subwatershed plans is a strategic initiative as part of the following goals of the Town’s Stormwater
Management Program:
• Address stormwater quantity (flooding) as an integral component within the program;
• Address stormwater quality as an integral function within the program; and
• Protect and restore natural stream corridors.
In 2009, the Town began a pilot subwatershed study, the Booker Creek Headwaters Subwatershed
Study, to assess stream conditions and identify potential stormwater project sites; this study was
included in the Town’s Stormwater Master Plan – Phase II (Jewell Engineering Consultants, PC,
2014).
The Booker Creek Watershed is approximately 6.3 square miles and includes five subwatersheds.
In 2015, the Town contracted with W.K. Dickson to complete individual studies of the four
remaining subwatersheds within the Booker Creek basin: Lower Booker Creek, Eastwood Lake,
Crow Branch, and Cedar Fork.
Systematic mapping of stormwater infrastructure is a large part of each subwatershed study. The
results of these subwatershed studies are used to prioritize projects that will help control existing
flooding, stabilize streams, and improve overall water quality in the Town’s watersheds.
Completion of the studies within the Booker Creek watershed has been a multi-year planning
process. For more information, see http://bookercreekplan.org/.
9.2 TOWN CODE OF ORDINANCES
9.2.1 Flood Damage Prevention Ordinance
The Town of Chapel Hill’s Flood Damage Prevention Ordinance (Chapter 5, Article IV)
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• restricts or prohibits uses that are dangerous to health, safety, and property due to water
or erosion hazards or that result in damaging increases in erosion, flood heights or
velocities;
• requires that uses vulnerable to floods, including facilities that serve such uses, be
protected against flood damage at the time of initial construction;
• controls the alteration of natural floodplains, stream channels, and natural protective
barriers, which are involved in the accommodation of floodwaters;
• controls filling, grading, dredging, and all other development that may increase erosion
or flood damage; and
• prevents or regulates the construction of flood barriers that will unnaturally
divert floodwaters or which may increase flood hazards to other lands.
This ordinance meets or exceeds the minimum National Flood Insurance Program (NFIP)
standards and authorizes the Town to implement the federal and state requirements at the local
level.
9.2.2 Erosion and Sediment Control
The Town’s Soil Erosion and Sedimentation Control Ordinance (Chapter 5, Article V), was originally
adopted in 1986 to address soil erosion and sedimentation control and prevent degradation of
area waterways, and was last updated in 2001. This ordinance and its enforcement contribute to
meeting the Town's National Pollutant Discharge Elimination System (NPDES) minimum
requirements for Construction Site Stormwater Runoff Control, and it meets or exceeds state
erosion control requirements.
For land development projects disturbing at least 20,000 square feet of land, an erosion and
sediment control permit is required. Single family development projects that that do not have to
install stormwater control measures on site or apply for erosion control permits but exceed 1,500
square feet of land disturbance are still reviewed and approved by the Town of Chapel Hill to
ensure that no sediment is being transported from the site or that drainage improvements have
no adverse impact on neighboring properties.
The Town’s erosion control program is administered by the Orange County Erosion Control
Division and enforced by Orange County. Both the Town and the County are local delegated
authorities to implement and enforce state erosion and sediment control requirements and have
had an inter-local agreement in place since 1986. The Town and County are currently reviewing
the 1986 agreement to consider updates that would more clearly define the services that will be
provided for MS4 compliance, a requirement to notify the Town if the county’s delegated program
is put on probation by NC Division of Energy, Mineral, Land Resources (NCDEMLR), and provide a
provision that reimbursement of any resulting legal defense and/or penalties may be required for
failure to implement the agreed upon program components.
9.2.3 Illicit Discharge Detection and Elimination (IDDE)
The Town of Chapel Hill adopted an IDDE Ordinance on November 14, 2016, as a new Article V of
Chapter 23 (Water, Sewers and Drainage) of the Town’s Code of Ordinances. The purpose of the
ordinance is to:
• regulate the contribution of pollutants to the stormwater drainage system,
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• prohibit illicit discharges and connections to the stormwater drainage system,
• prevent improper disposal of materials that degrade water quality, and
• establish legal authority to carry out all inspection, detection, monitoring procedures and
enforcement necessary to ensure compliance with the ordinance.
The IDDE Ordinance also provides criteria for assessing civil penalties. Prior to the adoption of
the IDDE Ordinance, the Town’s authority for IDDE enforcement and penalties was limited to
Sections 8-34 and 8-44 of the Code of Ordinances.
9.2.4 Land Use Management Ordinance (LUMO)
Development regulations and standards are documented in the Chapel Hill LUMO (Appendix A of
the Town’s Code of Ordinances). The LUMO was adopted in 2003 as a companion document to
the 2000 Comprehensive Plan. In 2015, a series of text amendment updates were proposed as a
result of the completion of the 2020 Comprehensive Plan, including a text amendment that
increased clarity in the regulations to improve enforcement and water quality protection. In June
2019, a text amendment was approved for Section 3.11 of the LUMO (Blue Hill District) to address
Session Law 2018-145, which affected local government authority over stormwater treatment
requirements for redevelopment projects.
The following summaries provide an overview of the relevant LUMO sections with respect to
water quality and the Town’s NPDES MS4 permit.
9.2.4.1 Resource Conservation District (RCD)
LUMO Section 3.6.3 establishes a Resource Conservation District (RCD) overlay zoning
designation that requires stream buffers along all perennial streams, intermittent
streams, and perennial waterbodies within the Town’s planning jurisdiction. The
purpose of the RCD is to:
• preserve the water quality of the Town's actual or potential water supply sources;
• minimize danger to lives and properties from flooding in and near the
watercourses to preserve the water-carrying capacity of the watercourses, and
to protect them from erosion and sedimentation;
• retain open spaces and greenways and to protect their environmentally-sensitive
character;
• preserve urban wildlife and plant life habitats from the intrusions of urbanization;
• provide air and noise buffers to ameliorate the effects of development; and
• preserve and maintain the aesthetic qualities and appearance of the Town.
The RCD Ordinance was incorporated into the LUMO in 2003 but was originally
established in 1984.
Streams subject to the RCD rules include those shown on the Town's Geographic
Information System (GIS) coverage, the most recent version of the U.S. Geological
Survey 1:24,000 scale (7.5 minute) topographic map, or the soils map in the U.S.
Department of Agriculture Orange County Soil Survey. All streams subject to the RCD
are field classified by Town staff using NC Division of Water Resources (NCDWR)
methodology, and RCD buffers are measured from the top of bank and must be
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surveyed. Buffers required on perennial waterbodies are measured from the mean
high-water mark.
9.2.4.2 Water Supply Watershed Protection Program
The North Carolina Water Supply Watershed Protection Rules adopted in 1992 required
that all local governments having land use jurisdiction within water supply watersheds
adopt and implement water supply watershed protection ordinances, maps, and
management plans. As a result, the Town of Chapel Hill established a Watershed
Protection District overlay zoning designation intended to be applied to a portion of the
New Hope Watershed draining to Jordan Lake in order to ensure long-term water quality
of the Jordan Lake Reservoir, to protect possible future sources of drinking water for the
Town and surrounding localities, and to control pollution sources affecting water
quality.
LUMO Section 3.6.4 establishes the Watershed Protection District, and includes
requirements for high density development, restrictions on use of toxic materials,
construction standards, and other performance standards. In 2015, a text amendment
was made to the Watershed Protection District to reflect changes that resulted from
adoption of the 2020 Comprehensive Plan update. Specifically related to water quality,
the changes in the 2015 text amendment were designed to (1) align local Watershed
Protection District regulations to match State requirements and exemptions, (2) remove
redundant stream buffer text, (3) clarify development options, (4) modify the
dimensional matrix to reflect Town-wide standards based on 2013 Council action, and
(5) make the steep slopes ordinance easier to read and use.
The area of the Watershed Protection District extends five miles from the normal pool
elevation of Jordan Lake Reservoir or the ridgeline of the watershed, whichever is less
(see Figure 2 below).
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Figure 2. Map of Jordan Lake Watershed Protection District (blue shading)
within the Town of Chapel Hill's zoning jurisdiction (green outline).
9.2.4.3 Jordan Watershed Riparian Buffer Protection Ordinance
In 2010, the Town incorporated the minimum requirements of the Jordan Nutrient
Strategy Rule (15A NCAC 02B.0267, as amended by Session Law 2009-484) for riparian
buffer protection into a Jordan Watershed Riparian Buffer Protection Ordinance,
adopted as LUMO Section 5.18. The riparian buffer is 50 feet wide directly adjacent to
intermittent streams, perennial streams, and perennial waterbodies, excluding
wetlands. This ordinance applies to uses or activities conducted within or outside of the
riparian buffer with hydrological impacts in violation of the diffuse flow requirements
set out in subsection 5.18.6(c).
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Streams subject to this ordinance are those shown on the most recent hard copy
paperbound version of the soil survey map prepared by the Natural Resources
Conservation Service of the United States Department of Agriculture, or the most recent
version of the 1:24,000 scale (seven and one-half (7.5) minutes) quadrangle topographic
maps prepared by the United States Geologic Survey (USGS). Town staff field verify all
stream classifications for streams subject to Jordan Watershed Riparian Buffers using
NCDWR methodology.
9.2.4.4 Steep Slopes
LUMO Section 5.3, Critical Areas and Environmental Performance Standards, cross
references the Town’s Erosion and Sediment Control Ordinance and establishes
limitations on the development of steep slope areas. The purpose of this section is to
minimize the grading and site disturbance of steep slopes by restricting land disturbance
on steep slopes and by requiring special construction techniques for development on
steep slopes. These provisions are intended to protect water bodies (streams and lakes)
and wetlands from the effects of erosion on water quality and water body integrity,
protect the plant and animal habitat of steep slopes from the effects of land
disturbance, and preserve the natural beauty and economic value of the town's wooded
hillsides.
A "steep slope" in Section 5.3 is defined as a slope that is equal to or steeper than fifteen
(15) percent and includes those areas of size four hundred (400) square feet or greater.
There are separate requirements for slopes 15% or greater and those 25% or greater.
9.2.4.5 Stormwater Management
LUMO Section 5.4 specifies stormwater management requirements for all development
projects that propose more than 20,000 square feet of land disturbance. The section
includes peak flow rate, volume, and water quality requirements for specified design
storms or precipitation depths. The water quality requirement states that “stormwater
treatment shall be designed to achieve average annual eighty-five (85) per cent total
suspended solids (TSS) removal and must apply to the volume of post-development
runoff resulting from the first one-inch of precipitation.”
A text amendment to the LUMO was approved on October 24, 2012, adding Section
5.19 - Jordan Watershed Stormwater Management for New Development, as required
by the NC General Assembly. The effective date was December 1, 2012. Development
of this new development rule was required to be completed and submitted to the NC
Environmental Management Commission by September 10, 2011. However, the NC
General Assembly then delayed this rule with Session Law 2012-200, and local
governments were barred from implementing this new development stormwater rule.
In addition, LUMO Section 3.11 was adopted on May 12, 2014, and established a specific
Blue Hill District (formerly the Ephesus-Fordham Form District) that included minimum
stormwater management standards specific to this district only for all new development
and redevelopment - new development or redevelopment in the Blue Hill District
received exemptions from Resource Conservation District (RCD), steep slope, and other
regulations, in exchange for treating at least 50% of existing impervious areas.
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In December 2018, the NC General Assembly restricted the ability of local governments
to require new or increased stormwater management controls for (i) preexisting
development or (ii) redevelopment activities that do not remove or decrease existing
stormwater controls (Session Law 2018-145). When a preexisting development is
redeveloped, either in whole or in part, increased stormwater controls shall only be
required for the amount of impervious surface being created that exceeds the amount
of impervious surface that existed before the redevelopment. This session law required
all local governments to adopt this change and update their stormwater ordinances,
regardless of the source of their regulatory authority.
As a result, the Town updated Section 3.11 on June 26, 2019, to provide two stormwater
management options in the Blue Hill District: conventional or enhanced
development. Under the conventional option, streams are subject to Resource
Conservation District (RCD) regulations and other LUMO regulations previously
exempted in this district, and only the net increase in impervious surface requires
stormwater management treatment. Under the enhanced stormwater option, the RCD,
steep slopes, and other previously exempt regulations in this district remain exempt,
and in exchange there is a requirement to treat 50% of total post-construction
impervious surfaces. Since the change in 2019, most development has chosen to
proceed voluntarily with the enhanced development option.
9.2.4.6 Tree Protection
LUMO Section 5.7 regulates the protection, installation, removal, and long-term
management of trees, shrubs, and soils within the Town’s jurisdiction. The following
tree canopy coverage standards are required for applications proposing tree removal
that require council approval, including special use permits, major special use permit
modifications, and conditional zoning district rezonings.
Table 4. Minimum tree canopy coverage standards by land use type.
Minimum Canopy
Land Use Type Coverage
Multi-Family Residential 30%
Commercial (Use Group C and Business, Office; 30%
Clinic; Funeral Home; and Hotel/Motel)
Institutional (Use Group B) 40%
Mixed Use, Other 40%
All Uses in Innovative, Light Industrial 20%
Conditional Zoning District (LI-CZD)
10 PARTNERSHIPS AND INTER-LOCAL AGREEMENTS
The Town works on a local and regional basis in cooperation with other local government agencies, state
and federal agencies, the University of North Carolina (UNC), and other organizations on a wide variety of
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water resources-related issues. The Town will continue to work together with these partners to meet the
challenges and regulations facing all of us within the Upper Cape Fear River watershed.
10.1 ORANGE COUNTY EROSION CONTROL
Through an inter-local agreement, Orange County’s Erosion Control Division administers, implements, and
enforces the Erosion and Sediment Control (E&SC) program for Chapel Hill, as well as other municipalities
within the county (Carrboro, Hillsborough). The Orange County Sediment and Erosion Control Program
effectively meets the maximum extent practicable (MEP) standard for Construction Site Runoff Controls
by permitting and controlling development activities disturbing one or more acres of land surface and
those activities less than one acre that are part of a larger common plan of development. Town and
Orange County staff work together regularly on enforcement of the Town’s erosion control requirements.
10.2 TOWN OF CARRBORO
The Town of Chapel Hill’s Stormwater Management staff coordinate with the Town of Carrboro’s
Stormwater program and staff regularly on projects of mutual interest. These projects include public
education and outreach, volunteer stream cleanup events, annual biological monitoring in the Bolin Creek
and Morgan Creek watersheds, stream restoration efforts in the Bolin Creek watershed, and stream
determinations for properties located in the vicinity of both jurisdictions. As of 2020, Chapel Hill is now
monitoring two long-term (reference) monitoring sites located in Carrboro (Morgan Creek at NC54 and
Bolin Creek at Waterside Drive). Town of Chapel Hill and Carrboro stormwater staff also work closely on
IDDE efforts across jurisdictions. In addition, the Town of Chapel Hill and Town of Carrboro have an inter-
local agreement to fund annual maintenance of a United States Geologic Survey (USGS) stream gage on
Bolin Creek at Village Drive.
10.3 UNIVERSITY OF NORTH CAROLINA AT CHAPEL HILL (UNC)
The Town of Chapel Hill’s Stormwater Management staff communicate regularly with UNC Stormwater
Management and UNC Energy Services staff to discuss items of mutual interest, coordinate public
education and IDDE efforts, and co-review UNC development plans. A member of the UNC staff serves
on the Town’s Stormwater Management Utility Advisory Board, and Town staff are involved in educational
and student research projects have been developed in collaboration with UNC’s Institute for the
Environment, and courses taught through the UNC Department of City and Regional Planning. Town
Stormwater staff also serve as collaborators on stormwater and water quality grants obtained by UNC and
other academic partners.
10.4 ORANGE WATER AND SEWER AUTHORITY (OWASA)
The Town of Chapel Hill’s Stormwater Management staff meet with OWASA engineering staff regularly
regarding development projects via the Town’s Technical Review Team meetings and regarding Capital
Improvement Projects. The Town’s staff also coordinate with OWASA Operations and Maintenance staff,
UNC Stormwater Management staff, and Town of Carrboro stormwater staff on water quality and illicit
discharge issues in our shared jurisdictions.
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