WSMU_CARY_WSWP Ordinance_20230629 (2)

ACT 25
Ordinance to Adopt ACT 25 Amendments
To the Land Development Ordinance
Town of Cary, NC
1. Chapters 4, 7, and 12 of Appendix A, Land Development Ordinance, of the Code of Ordinances, Town
of Cary, North Carolina, are hereby amended to read as follows:
4.4.6 Watershed Protection Overlay
(A) Purpose and Intent
(3) Engineered stormwater control structure!) measures and the best management
practices as listed in the Department of Environmental Quality and Natural Resources'
State Design Manual.
(B) Applicability
(3) Sedimentation and Erosion Control
Responsible control of erosion and sedimentation is crucial to the protection of
stormwater quality and the continued proper function of the measures required in this
section. Requirements pertaining to sedimentation and erosion control are addressed
in Section 7-4 14.4 of this Ordinance.
(D) Overview of High Density and Low Density Development Options
(4) Runoff Control
Engineered stormwater controls measures intended to contain the runoff from the
first one (1) inch of rainfall are required in any development utilizing the High Density
Option in either watershed.
(F) Limitations on Impervious Surface Area and Density
(2) High Density Option
High Density Option development proposals may be approved, provided that the
development applications are consistent with the following standards:
TABLE 4.4-5: MAXIMUM IMPERVIOUS SURFACE LIMITS: HIGH DENSITY OPTION
Suburban-New Urban-New Existing Urban

Residential Non- Residential Non- Residential and
Residential Residential Non-
Residential
Swift Creek Watershed
Maximum Two and one- half The Six(6.0) dwelling The impervious The impervious
Impervious (2.5) dwelling units impervious units per acre east area allowed area allowed
Surface per acre not to area allowed of Holly Springs and under the under the
Limits exceed thirty(30) under the Jones Franklin underlying underlying
percent impervious underlying Roads. Greater than general use general use
surface area. general use six (6.0) units per zoning districts, zoning districts,
zoning acre west of Holly not to not to
districts, not Springs and Jones exceed seventy exceed seventy
to Franklin Roads, not (70) percent. (70) percent.
exceed thirty to exceed seventy
(30) percent. (70)
percent impervious
surface area.
Sewer Required
Impoundment Required to contain and treat the runoff from the first one (1) inch of rainfall and to achieve a
and minimum of eighty-five (85) percent average annual removal for Total Suspended Solids
Maintenance (TSS). Public or private maintenance. [Other BMPs SCMs besides impoundments may be
available; consult the Department of Environmental and Natural Resources' Quality State
Design Manual for Best Management Practices Related to Stormwater Control.]
Jordan Lake Watershed
Where new development exceeds the Low Density Option Standards above,engineered stormwater controls
measures shall be used to control and treat runoff from the first inch of rainfall and to achieve a minimum of
eighty-five (85) percent average annual removal for Total Suspended Solids (TSS). Development shall not
exceed seventy(70) percent impervious surface area.
Jordan Lake Watershed Critical Area
Where proposed development exceeds the Low Density Option Standards above,engineered stormwater
controls measures are required to control and treat runoff from the first inch of rainfall and to achieve a
minimum of eighty-five (85) percent average annual removal for Total Suspended Solids (TSS). Development
shall not exceed fifty(50) percent impervious surface area.
(G) Engineered Stormwater Control Measures Structures
(1) Ownership and Design Requirements
Stormwater control structures measures shall be owned by a property owner's association,
or, for non-residential or multi-family development,the owner of the property. All
stormwater control structures measures shall be designed by either a North Carolina
registered professional engineer or landscape architect,to the extent that the N.C. General

Statutes allow. Other stormwater systems shall be designed by a North Carolina registered
professional with qualifications appropriate for the type of system required;these
registered professionals are defined as professional engineers, landscape architects, to the
extent that the N.C. General Statutes allow and land surveyors, to the extent that the design
represents incidental drainage within a subdivision, as provided in N.C. General Statutes.
(2) Structures Measures Required for High-Density Option
(a) All development under the high-density option shall use engineered stormwater control
structures measures as a primary treatment system. Engineered stormwater control
structures measures shall be designed for specific pollutant removal according to
modeling techniques approved by the North Carolina Department of Environmental
and Natural Resources Quality. Specific requirements for these systems shall be in
accordance with the State's Minimum Design Criteria and Cary's Standard Engineering
Details and Specifications Manual.
(b) SCM's that control stormwater on a runoff volume basis may be used in lieu of an SCM
designed for specific pollutant removal in accordance with Section 4.4.6(G)(2)(a)
provided that the post development volume of stormwater leaving the site is equal to
or less than the predevelopment volume for the ninetieth (90th) percentile storm.
(3) Ground Cover Required
In addition to the vegetative filters required in the Cary's Standard Engineering Details and
Specifications Manual, all land areas outside of the engineered stormwater control
structures measures shall be provided with a ground cover sufficient to restrain erosion
within fifteen (15) days after any land disturbance. Upon completion of the stormwater
control structure measure, a permanent ground cover shall be established and maintained
as part of the maintenance plan described in Section 4.4.6(G)(9) below.
(4) Legal Description Required
A legal description of the area containing the stormwater control structure measure shall
be prepared and filed consistent with Section 4.4.6(G)(9) as a separate deed with the Wake
appropriate County's Register of Deeds along with any easements necessary for general
access to the stormwater control structure measure. The deeded area shall include
sufficient area to perform inspections, maintenance, repairs and reconstruction. The
deeded area shall include, but is not limited to detention pond, vegetative filters, all pipes
and water control structures, berms and dikes.
(5) Computation of Total Built-Upon Area
Qualifying areas of the stormwater control measure may be considered pervious when
computing total built-upon area. However, if the structure measure is used to compute the
percentage built-upon area for one (1) site, it shall not be used to compute the built-upon
area for any other site or area.
(6) Wet Detention Ponds Stormwater Control Measures
Wet detention ponds Stormwater Control Measures(SCM) including Regional SCM's
designed following the State Design Manual and Cary's Standard Engineering Details and
Specifications Manual, properly constructed, with all required financial assurances and

maintenance agreements in place may be regarded as adequate to satisfy the
impoundment requirements of the entire upstream contributory drainage basin.
(7) Posting of Financial Security Required
All engineered stormwater control structures measures shall be conditioned on the posting
of adequate financial assurance for the purpose of maintenance, repairs, or reconstruction
necessary for adequate performance of the stormwater control structures measures.
Financial assurance shall be in the form of the following:
(a) Acceptable Forms of Security
Acceptable financial security shall be deposited with the Town to ensure that the
engineered stormwater control structure measure is adequately maintained.The
permit applicant shall deposit with the Town of Cary either cash or an evergreen letter
of credit as financial security approved by the Town that is readily convertible into cash
at face value. The cash or evergreen letter of credit shall be in an amount equal to
fifteen (15) percent of the total cost of the stormwater control structure measure.e-r
the estimated cost of maintaining the stormwater control structure over a ten (10) year
period, whichever is greater. The estimated cost of maintaining the stormwater control
structure shall be consistent with the approved operation and maintenance plan or
manual provided to the Town by the developer. The amount shall be computed by
estimating the maintenance cost for twenty five (25)years and multiplying this amount
by two fifths (2/5) or 0.4.
(b) Operation and Maintenance Agreement
For all development built under the high density development option, the owner shall
enter into a binding Operation and Maintenance Agreement between the Town and all
persons having a freehold estate in the development. Said Agreement shall require the
owning entity to inspect, maintain, repair and, if necessary, reconstruct the stormwater
control structure measure in accordance with the operation and management plan or
manual provided by the owner. The owner of the stormwater control structure measure
shall file the Operation and Maintenance Agreement with the Wake appropriate
County's Register of Deeds.
(c) Default Under the Cash or Evergreen Letter of Credit
Upon default of the owning entity to maintain, repair and, if necessary, reconstruct the
stormwater control structure measure in accordance with the Operation and
Maintenance Agreement,the Town shall obtain and use all or any portion of the
financial security to make necessary improvements based on an engineering estimate.
Such expenditure of funds shall only be made after exhausting all other reasonable
remedies seeking the owning entity to comply with the terms and conditions of the
Operation and Maintenance Agreement. The Town shall not return any of the unused
deposited cash funds, which shall be retained for maintenance.
(8) Inspections for Stormwater Control Structures Measures
(a) The Stormwater Manager shall inspect the stormwater control structure measure after
the owning entity notifies the Stormwater Manager that all construction-related
work has been completed.At this inspection,the owning entity shall provide:

1. The executed deed, related easements, operation and maintenance
agreement and survey plat for the stormwater control structure measure
ready for filing with the Wake appropriate County's Register of Deeds;
2. A certification sealed by a qualified professional stating that the stormwater
control structure measure is complete and complies fully with the approved
plans and specifications.
3. Reproducible as built plans and/or record drawings showing best
managcmcnt practices stormwater control measures.
(b) The Stormwater Manager shall review the documents submitted by the owning entity
and the Towns- Cary's inspection report.
1. If the Stormwater Manager approves the inspection report, deed and
easements, and acccpts the certification, tThe owning entity shall file the
Operation and Maintenance Agreement, deed and easements with the Wake
appropriate County's Register of Deeds and provide proof of recordation to
the Stormwater Manager. Upon Following receipt of proof of recordation, and
approval of Cary's inspection, deed(s), easement(s), and the certification by
the engineer of record,the Stormwater Manager will issue a Certificate of
Watershed Protection Compliance.
2. If deficiencies are found, the Stormwater Manager shall direct the owning
entity to correct the deficiencies, make improvements and inspections
and/or correct documents and resubmit proof of the corrections and/or
improvements to the Stormwater Manager.
(c) A Certificate of Occupancy shall not be issued for any building within the permitted
development until the Town Cary has approved the stormwater control structure
measure, as provided in Section 4.4.6(G)(8)(b).
(d) The owner of each stormwater control structure measure shall submit a Maintenance
Inspection Report annually on the anniversary date of the Operation and Maintenance
Agreement recording Certificate of Watershed Compliance, to the Stormwater
Manager. A qualified professional, licensed in the state of North Carolina, must
conduct the inspection. Records of inspection shall be maintained on forms approved
or supplied by the North Carolina Division Department of Environmental Management
Quality and shall be provided to the Stormwater Manager in a timely manner.
(e) In the event the annual inspection reveals the need for corrective action or
improvements, the Stormwater Manager shall notify the owning entity of the needed
improvements and the date by which the corrective action is to be completed.All
improvements shall be made consistent with the plans and specifications of the
stormwater control structure measure and the operation and maintenance plan or
manual as provided by section 4.4.6(G)(7)(b). After all corrective actions have been
taken, the qualified professional shall re-inspect the stormwater control structure
measure and certify to the town that the appropriate corrective actions have been
taken.

(f) Appeals of any order, requirement, decision or determination made by the Stormwater
Manager may be made to and decided by the Zoning Board of Adjustment Town
Council.
(9) Maintenance and Upkeep
(a) An operation and maintenance plan or manual shall be provided by the developer for
each stormwater control structure measure, indicating what operation and
maintenance actions are needed, what specific quantitative criteria will be used for
determining when those actions are to be taken and who is responsible for those
actions. The plan shall clearly indicate the steps that will be taken for restoring a
stormwater control structure measure to design specifications if a failure occurs.
(b) Landscaping and grounds management shall be the responsibility of the owning entity.
However, vegetation shall not be established or allowed to mature to the extent that
the integrity of the stormwater control structure measure is diminished or threatened,
or to the extent of interfering with any easement or access to the stormwater control
structure measure.
(c) Except for general landscaping and grounds management,the owning entity shall
notify the Stormwater Manager prior to any repair or reconstruction of the stormwater
control structure measure. All improvements shall be made consistent with the
approved plans and specifications of the stormwater control structure measure and
the operation and maintenance plan or manual. After all repairs have been completed,
the owning entity shall engage the services of a qualified professional, licensed in the
state of North Carolina, to inspect said improvements and to issue a report to the
Stormwater Manager. The owning entity shall perform all additions, changes, or
modifications noted in the inspection report supplied by the qualified professional in a
timely manner.
(d) The Stormwater Manager retains the right to perform inspections, deemed necessary
by the Stormwater Manager, on any stormwater control structure measure.
(e) Amendments to the plans and specifications of the stormwater control structure
measure and/or the operation and maintenance plan or manual shall be approved by
the Stormwater Manager. Proposed changes shall be prepared by a qualified
professional.
1. If the Stormwater Manager approves the proposed changes,the owning entity of
the stormwater control structure measure shall file sealed copies of the revisions
with the Office of the Stormwater Manager.
2. If the Stormwater Manager disapproves the changes, the proposal may be revised
and resubmitted to the Town Council as a new proposal. If the proposal has not
been revised and is essentially the same as that already reviewed, it shall be
returned to the applicant.
(f) If the Town Council or Stormwater Manager finds that the operation and maintenance
plan or manual is inadequate for any reason,the Stormwater Manager shall notify the
owning entity of any required changes and the owning entity shall prepare and file
copies of the revised agreement first with the Wake appropriate County's Register of

Deeds. The owning entity shall then file a copy certified by the Register of Deeds with
the Office of the Stormwater Manager.
(H) Clustered Development Option
(3) The remaining undeveloped portion of the tract shall remain in an undisturbed
vegetated or natural state. Where the development has an established property
owner's association,the title to the open space area shall be conveyed to the
association. Where a property owner's association has not been established, a
maintenance agreement shall be filed with the Wake County's Register of Deeds.
7.3 STORMWATER MANAGEMENT
7.3.1 Purpose and Definitions
(A)This section is intended to protect water quality for present and future residents of the Town
and surrounding regions by limiting the amount of pollutants, including but not
limited to nitrogen and phosphorus, in stormwater runoff. Specific objectives include:
control of nitrogen and phosphorus export from development, control of peak stormwater
runoff, and the use of best management practices.
(B) For the purpose of this section 7.3, the following definitions shall apply:
LARGER COMMON PLAN OF DEVELOPMENT OR SALE
Any area where multiple separate and distinct construction or land disturbing activities
will occur under one (1) plan. For purposes of this definition only, a plan is any
announcement or piece of documentation (including but not limited to a sign, public notice
request, or computer design) or physical demarcation (including but not limited to boundary
signs, lot stakes, or survey markings) indicating that construction activities may occur on a
specific plot.
A site where multiple separate and distinct development activities may be taking place at
different times on different schedules but governed by a single development plan
regardless of ownership of the parcels. Information that may be used to determine a
"common plan of development" include plats, blueprints, marketing plans, contracts,
building permits, public notices or hearings, zoning requests, and infrastructure
development plans. Common Plan of Development is synonymous with "Larger Common
Plan of Development".
7.3.2 Nutrient Reduction Requirements
(A) Nitrogen and Phosphorus Control Plan Required
For purposes of this section, nitrogen and phosphorus control plans shall be required for
the following:

(1) Any activity that, alone or as part of a larger common plan of development or sale,
disturbs greater than one (1) acre of land in order to establish, expand, or modify a single-
unit or duplex residential development or a recreational facility.
(2) Any activity that, alone or as part of a larger common plan of development or sale,
disturbs greater than twelve thousand (12,000)square feet of land in order to establish,
expand or modify a multifamily residential development or a commercial, industrial or
institutional facility.
(3)Any redevelopment alone or as part of a larger common plan of development or sale in
order to establish, expand, or modify a multifamily residential development or a
commercial, industrial or institutional facility that increases built upon area and has an
existing Stormwater Management Plan is subject to this rule regardless of disturbed area.
{ } (4)Any grubbing, stump removal, and/or grading activity that disturbs greater than
twelve thousand (12,000) square feet.
(4)(5) Demolition and subsequent construction upon a previously developed site.
(B) Exemptions
(1) For purposes of this section, development or land disturbance shall not include
agriculture, mining, or forestry activities.
(2) Existing development as of March 1, 2001 in the Neuse River Basin, is not subject to
the requirements of this Section. Expansions to existing development must meet the
requirements of this Section. The impervious surface area of the existing development is
not required to be included in the nitrogen load attributed to the site expansion; All
calculations must use the approved accounting tool. nitrogcn calculations must follow Town
procedures for allocating undeveloped land to thecite.
(3) Redevelopment and/or rebuilding activity which results in no net increase in the built-
upon area from that that previously existed and which provides equal or greater stormwater
control than that provided by previous development.
(4) In the Cape Fear River Basin any proposed new development that would replace or
expand structures or improvements that existed as of December 1, 2001, and that would
not result in a net increase in built-upon area shall not be required to meet the nutrient
loading targets or high-density requirements, in accordance with Section 4.4.6(D), except to
the extent that it shall provide stormwater control at least equal to the previous
development.

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(C) Calculation of Nitrogen and Phosphorus Export
(1) The nitrogen export from each development in the Neuse River Basin must be calculated
per Town procedures and approved by the Stormwatcr Manager or his or her designee. This export
will be calculated in pounds per acre per year (Ib/ac/yr). For calculating nitrogen export, refer to
Controlling Urban Runoff: A Practical Manual for Planning and Designing Urban BMPs (Schueler's
Simple Method), or to the Neuse River Basin: Model Stormwatcr Program for Nitrogen Control
Manual (Methods 1 & 2), or for calculating nitrogen export loading:
(a) Method 1 is intended for residential developments where lots arc shown but the actual
footprint of the buildings is not shown on the plans.
(b) Method 2 is for residential, commercial, and industrial developments when the entire
footprint of the buildings, parkin

(c) The Schculer Simple Method may be used for new development on a case by case basis
as approved by the Town.
(2) The developer shall determine the need for engineered stormwater controls to meet the
Goading rate targets in the Cape Fear River Basin by using the most current approved accounting tool
for nutrient loading approved by the North Carolina Environmental Management Commi"lion
pursuant to 15A NCAC 2B .0265.
(D) (C) Nitrogen and Phosphorus Export Standards
(3) Development subject to this section 7.3 shall attain a maximum nitrogen loading rate
on-site of six(6) pounds per acre per year for single-unit, detached and duplex
residential development and ten (10) pounds per acre per year for other development,
including multi-family residential, commercial and industrial and shall meet any
requirements for engineered stormwater controls otherwise imposed by the LDO. An
applicant may achieve the additional reductions in nitrogen and phosphorus loading
required by this section by making offset payments to the North Carolina Ecosystem
Enhancement Program North Carolina Division of Mitigation Services contingent upon
the acceptance of payments by that program. An applicant may propose other offset
measures, including providing his or her own offsite offset or utilizing a private seller.
All offset measures permitted by this ordinance shall meet the requirements of 15A
NCAC 02B .0273 (2)through (4) and 15A NCAC 02B .0240.0714.
TABLE 7.3-1: NITROGEN/PHOSPHORUS EXPORT REDUCTION OPTIONS
Residential Commercial/Industrial/Institutional/Local
Government/Multifamily Residential
If the computed export is less than 6.0 If the computed export is less than 10.0
Ibs/ac/yr, then the owner may either: Ibs/ac/yr, then the owner may either:
Install BMP SCMs to remove enough Install S-M-P SCMs to remove enough nitrogen
nitrogen to bring the development down to to bring the development down to 3.6
3.6 lbs/ac/yr in the Neuse River Basin. lbs/ac/yr in the Neuse River Basin. Install
Install BMP SCMs to bring the nitrogen BMP SCMs to bring the nitrogen down to 2.2
down to 2.2 lbs/ac/yr and phosphorus to lbs/ac/yr and phosphorus to 0.82 lbs/ac/yr
0.82 lbs/ac/yr in the Upper New Hope and in the Upper New Hope and the nitrogen
the nitrogen down to 4.4 lbs/ac/yr and the down to 4.4 lbs/ac/yr and the phosphorus to
phosphorus to 0.78 lbs/ac/yr Lower New 0.78 lbs/ac/yr Lower New Hope in the Cape
Hope in the Cape Fear River Basin. Fear River Basin.

Pay a one-time offset payment to bring the Pay a one-time offset payment to bring the
nitrogen down to the 3.6 lbs/ac/yr in the nitrogen down to the 3.6 lbs/ac/yr in the
Neuse River Basin. Pay a one-time offset Neuse River Basin. Pay a one-time offset
payment to bring the nitrogen down to 2.2 payment to bring the nitrogen down to 2.2
lbs/ac/yr and phosphorus to 0.82 lbs/ac/yr lbs/ac/yr and phosphorus to 0.82 lbs/ac/yr
in the Upper New Hope and the nitrogen in the Upper New Hope and the nitrogen
down to 4.4 lbs/ac/yr and the phosphorus down to 4.4 lbs/ac/yr and the phosphorus to
to 0.78 lbs/ac/yr Lower New Hope in the 0.78 lbs/ac/yr Lower New Hope in the Cape
Cape Fear River Basin. Fear River Basin.
Do a combination of AMP SCMs and offset Do a combination of AMP SCMs and offset
payment to achieve a 3.6 lbs/ac/yr export payment to achieve a 3.6 lbs/ac/yr export in
in the Neuse, 2.2 lbs/ac/yr nitrogen and the Neuse, 2.2 lbs/ac/yr nitrogen and 0.82
0.82 lbs/ac/yr phosphorus in the Upper lbs/ac/yr phosphorus in the Upper New Hope
New Hope and 4.4 lbs/ac/yr nitrogen and and 4.4 lbs/ac/yr nitrogen and 0.78
0.78 lbs/ac/yr phosphorus in the Lower lbs/ac/yr phosphorus in the Lower New
New Hope. Hope.
If the computed nitrogen export is greater If the computed nitrogen export is greater
than 6.0 lbs/ac/yr, the owner must use on- than 10.0 lbs/ac/yr, the owner must use on-
site or regional BMP SCMs to bring the site or regional BMP SCMs to bring the
development's export down to 6.0 development's export down to 10.0 lbs/ac/yr.
lbs/ac/yr. Then, the owner may use one of Then, the owner may use one of the three
the three options above to achieve the options above to achieve the reduction
reduction between 6.0 and 3.6 lb/ac/yr in between 10.0 and 3.6 lb/ac/yr in the Neuse
the Neuse River Basin, 2.2 lbs/ac/yr in the River Basin, 2.2 lbs/ac/yr in the Upper New
Upper New Hope or 4.4 lbs/ac/yr in the Hope or 4.4 lbs/ac/yr in the Lower New Hope
Lower New Hope of the Cape Fear River of the Cape Fear River Basin.
Basin.
Once it has been determined that an offset payment is forthcoming, the owner shall furnish
the Town with evidence that the payment for the reductions in nitrogen and/or phosphorus has been
made prior to the Town's issuance of a grading permit.
(4) The nitrogen and phosphorus export standards in this ordinance are supplemental to,
not replacements for, stormwater standards otherwise required by federal, state or local
law, including without limitation any riparian buffer requirements applicable to the location
of the development. This includes, without limitation,the riparian buffer protection
requirements of 15A NCAC 2B .0267.,and .0268 and .0714.
(D) Calculation of Nitrogen and Phosphorus Export
(1) The developer shall determine the need for engineered stormwater controls to meet the
loading rate targets in the Cape Fear River Basin and Neuse by using the most current
approved accounting tool for nutrient loading.
(2) Neuse River buffers and Jordan Lake Buffers required by the Department of
Environmental Quality may not be used for compliance with nutrient reduction

requirements; however, any portion of Zone 1, Zone 2, or Zone 3 UTB may be claimed as
Protected Forest in the approved accounting tool if all the following are met:
(a) No easements, including but not limited to Public or Private Utilities, Retaining
Walls, Access, Greenway, Drainage, or Stormwater Control Structure and Access
easements, may be located within the area claimed as protected forest.
(b)The area claimed as protected forest must be recorded as Permanently Protected
on the plat.
(c)Allowable activities within the Protected Forest are limited to those related to
removal of nuisance and invasive and diseased or dying vegetation or in the interest of
protecting human safety or property damage.
7.3.3 Town of Cary NPDES Phase II Post Construction Runoff Controls
To meet the requirements of the Town of Cary NPDES Phase II Permit any new development or
redevelopment as of July 1, 2005, not exempted pursuant to Section 7.3.2(B) must meet either
the low density or high density option requirements described below and in the Neuse Rules.
New development or redevelopment in the Swift Creek or Jordan Lake Watersheds must meet
the requirements of Section 4.4.6 of the LDO. For purposes of this Section 7.3.3, impervious
surface area shall be calculated pursuant to Section 4.4.6(D)(2) of the LDO and the provisions
of Section 4.4.6(G) of the LDO shall apply to all engineered stormwater control measures.
(A) Low Density Projects, having no more than two (2) dwelling units per acre or no more than
twenty-four(24) percent impervious surface area for all residential and non-residential
development, shall transport stormwater runoff by vegetated conveyances to the maximum
extent practicable.
(B) High Density Projects, having more than two (2) dwelling units per acre or more than twenty-
four(24) percent impervious surface area for all residential and non-residential development,
shall implement stormwater control measures that comply with each of the following standards:
(1) The stormwater control measures shall control and treat the difference between the
pre-development and post-development conditions for the one (1) year twenty-four(24)
hour storm. Runoff volume drawdown shall be a minimum of twenty-four(24) hours, but not
more than one hundred twenty(120) hours.
(2) Stormwater control measures shall be designed to achieve a minimum of eighty-five
(85) percent average annual removal for Total Suspended Solids (TSS).
7.3.34 Peak Runoff Control
7.3.4 Allowable Best Management Practices
Neuse River buffers and Jordan Lakc Buffers required by the Division of Water Resources may not
buffers (including locally required buffers) may be used as nitrogen control BMPs. All BMPs shall
meet the standards of the most current version of the North Carolina Department of Environment
and Natural Resources Best Management Practices Manual ("BMP Manual"). If specifications or

guidelines of the BMP Manual arc more restrictive or apply a higher standard than other laws or
regulations, that fact shall not prevent application of the specifications or guidelines in the BMP
Manual arc amended subsequent to the submittal of an application for approval pursuant to this
section 7.3 but prior to approval,the new information shall control and shall be utilized in reviewing
the application and in implementing this section 7.3 with regard to the application. Whenever an
applicant proposes to utilize a practice or practices not designed and constructed in accordance with
the criteria and specifications in the BMP Manual, the applicant shall have the burden of
demonstrating that the practicc(s) will satisfy the minimum water quality and quantity performance
standards of this section 7.3. The applicant may be required to provide the documentation,
calculations, and examples necessary to determine whether such an affirmative showing is made.
If more than one BMP is installed in series on a development,then the removal rate shall be
determined through serial rather than additive calculations. For example, if a wet detention pond
discharges through a UTB,then the removal rate shall be estimated to be forty seven and five tenths
{17.5) perccnt.The pond removes twenty five (25) perccnt of the nitrogen and discharges seventy
five (75) percent into the buffer. The buffer then removes thirty(30) percent of the nitrogen
discharged from the pond, which is twenty two and five tenths (22.5) perccnt.The sum of twenty five
{25) and twenty two and five tenths (22.5) is forty seven and five tenths (47.5). The removal rate is
not twenty five (25) percent plus thirty(30) percent.
7.3.5 Maintenance of Best Management Practices Stormwater Control Measures
All best management practices that are implemented to achieve nitrogen or phosphorus reduction
and flow attenuation will require complete legal documentation and a maintenance plan and must
comply with all requirements of Section 4.4.6(G), Engineered Stormwater Control Measures
Structures.
7.3.6 Reserved
7.3.7 Town of Cary NPDES Phase II Post Construction Runoff Controls
To meet the requirements of the Town of Cary NPDES Phase II Permit any new development or
redevelopment as of July 1, 2005 not exempted pursuant to Section 7.3.2(B) must meet either the
low density or high density option requirements described below. Ncw development or
redevelopment in the Swift Creek or Jordan Lake Watersheds must meet the requirements of
calculated pursuant to Section 4.4.6(D)(2) of the LDO and the provisions of Section 4.4.6(G) of the
LDO shall apply to all engineered stormwater control structures.
(A) Low Density Projects, having no more than two (2) dwelling units per acre or no more than
twenty four(24) percent impervious surface area for all residential and non residential development,
shall transport stormwater runoff by vegetated conveyances to the maximum extent practicable.
(B) High Density Projects, having more than two (2) dwelling units per acre or more than twenty
four (24) percent impervious surface area for all residential and non residential development, shall
(1) The stormwater control measures shall control and treat the difference between the pre
development and post development conditions for the one (1)year twenty four(24) hour storm.
hundred twenty(120) hours.

(2) Engineered stormwatcr control structures shall be deigned to achieve a minimum of
eighty five (85) percent average annual removal for Total Suspended Solids (TSS).
7.3.86 Variance
To the extent any state or federal law or regulations requires the Town to establish a variance
procedure for any requirement of this section 7.3,excluding section 7.3.6,the variance procedure
established in Section 4.4.6(1) of the LDO shall be utilized.The provisions of section 7.3.6 shall not
be subject to this requirement.
12.4 OTHER KEY TERMS DEFINED
When used in this Ordinance, the following words and terms shall have the meaning set forth in this
section, unless other provisions of this Ordinance specifically indicate otherwise.
APPROVED ACCOUNTING TOOL
The most recent version of the accounting tool for calculating nutrient loading and reduction
approved by the North Carolina Division of Energy, Mineral, and Land Resources for the relevant
geography and development type under review.
DEVELOPMENT, EXISTING
For the purposes of Chapters 4.4.6 and 7.3 only, the Watershed Protection Overlay district only,
existing development includes those projects meeting at least one (1) of the following criteria:
• Development having a common law vested right, which is a substantial expenditure of
resources (e.g., time, labor, money) based on a good faith reliance upon having received a valid local
government approval to proceed with the project;
• Having a current building permit issued by the Town;
• Having an approved development plan issued by the Town as authorized by the G.S. 160D-108;
108.1; or
• In Watershed Protection Overly district only,Cconforming single-unit lots of record that
received final plat approval before July 1, 1993.
• Development in the Neuse River Basin prior to March 1, 2001.
DEVELOPMENT APPROVAL
An administrative or quasi-judicial approval made pursuant to N.C.G.S. 160D that is written and
that is required prior to commencing development or undertaking a specific activity, project, or
development proposal. Development approvals include, but are not limited to, zoning permits,
development plan approvals, special use permits, variances, and certificates of appropriateness. The
term also includes all other regulatory approvals required by regulations adopted pursuant to
N.C.G.S. 160D, including plat approvals, permits issued, development agreements entered into, and
building permits issued.

ENGINEERED STORMWATER CONTROL STRUCTURE
Stormwater control structures designed by an engineer or landscape architect to control
,
ENGINEERED STORMWATER CONTROL MEASURE
A physical device designed to trap, settle out,filter, or otherwise remove pollutants from stormwater
runoff; to alter or reduce stormwater runoff velocity, amount,timing, or other characteristics; to
approximate the pre-development hydrology on a developed site; or to achieve any combination of
these goals. Engineered stormwater control measures include physical practices such as
constructed wetlands, vegetative practices, vegetated conveyances, filter strips, grassed swales, and
other methods installed or created on real property. "Engineered stormwater control measure" is
synonymous with "structural practice," "Primary SCM", "stormwater control facility," "stormwater
control practice," "stormwater treatment practice," "stormwater management practice," "stormwater
control measure," "structural stormwater treatment system," and similar terms used in this
ordinance. It is a broad term that may include practices that do not require design by a professionally
licensed engineer.
IMPERVIOUS SURFACE AREA
Any hard-surfaced, man-made area that allows little or no infiltration of precipitation into the soil.
Impervious surface areas include that portion of a development project that is covered by buildings;
areas paved with concrete, asphalt or brick; gravel road; recreation facilities such as tennis courts;
patios, driveways, and streets. "Impervious surface area" does not include slatted decks;-a-n-et the
water surface area of a swimming pool; a surface of number 57 stone, as designated by the
American Society for Testing and Materials, laid at least four inches thick over a geotextile fabric; a
trail as defined in N.C.G.S. 113A-85 that is either unpaved or paved as long as the pavement is
porous with a hydraulic conductivity greater than 0.001 centimeters per second (1.41 inches per
hour); or landscaping material, including, but not limited to, gravel, mulch, sand, and vegetation,
placed on areas that receive pedestrian or bicycle traffic or on portions of driveways and parking
areas that will not be compacted by the weight of a vehicle, such as the area between sections of
pavement that support the weight of a vehicle.
LOAD
Means the mass quantity of a nutrient or pollutant released into surface waters over a given time
period. Load in this ordinance refers to pounds of nitrogen or phosphorus per year.
LOADING RATE
Means the mass quantity of a nutrient or pollutant released from a given area into surface waters
over a given time period. Loading rate in this ordinance refers to pounds of nitrogen or phosphorus
per acre per year.
MINIMUM DESIGN CRITERIA OR "MDC"
The requirements for siting, site preparation, design and construction, and post-construction
monitoring and evaluation necessary for the issuance of stormwater permits that comply with State
water quality standards adopted pursuant to G.S. 143-214. As defined in 15A NCAC 02H.1002(24).

PRIMARY SCM
A wet pond, stormwater wetland, infiltration system, sand filter, bioretention cell, permeable
pavement, green roof, rainwater harvesting, or an approved new stormwater technology that is
designed, constructed and maintained in accordance with the MDC.
PROJECT
For the purposes of Chapters 4.4.6 and 7.3 only, the proposed development activity for which an
applicant is seeking a stormwater permit from the state or other entity in accordance with this
Section. "Project" shall exclude any land adjacent to the area disturbed by the project that has been
counted as pervious by any other development regulated under a federal, State, or local stormwater
regulation. Owners and developers of large developments consisting of many linked projects may
consider developing a master plan that illustrates how each project fits into the design of the large
development.
STORMWATER DESIGN MANUAL
The State Stormwater Design Manual approved by the Department for the proper implementation of
the State Minimum Design Criteria for engineered stormwater controls. All references herein to the
Design Manual are to the latest published edition or revision.
2. The Town Council hereby directs that a supplement to the Town Code of Ordinances, including
Appendix A, Land Development Ordinance, shall be prepared and printed reflecting these
amendments.
Adopted: March 23, 2023
Effective: March 23, 2023