Sec. 14.6.1. Purpose

Sec. 14.6.2. Applicability

Sec. 14.6.3. Protecting Riparian Buffers

Sec. 14.6.4. Nutrient Reduction Requirements

Sec. 14.6.5. Peak Runoff Control

Sec. 14.6.6. Allowable Best Management Practices

Sec. 14.6.7. Maintenance of Best Management Practices

Sec. 14.6.8. Modification by Variance

Sec. 14.7.1. Purpose

Sec. 14.7.2. Applicability

Sec. 14.7.3. Enforcement and administration of article

Sec. 14.7.4. Depositing certain substances in storm sewer system

Sec. 14.7.5. Obstructing storm sewer system

Sec. 14.7.6. Permit required for construction, repair or alteration of storm sewer systems.

Sec. 14.7.7. Inspection by Town Manager or designee

Sec. 14.7.8. Nuisances

Sec. 14.7.9. Notice to property owner of obstruction

Sec. 14.7.10. Violations; penalties

Sec. 10.3.12. Stream Buffers (revision to UDO)

Sec. 14.1.15 (c) Maintenance Responsibility, Replacement of Damaged Vegetation, and Associated Fines (revision to UDO)

Sec. 2.1.4 Definitions (revisions and amendments to UDO)

Ordinance 00-018 was adopted 7/27/00 and became effective 3/1/01. Amendments to the ordinance were approved 4/12/01

Chapter 14, Part 6, Stormwater Management Plan, is added to the Cary Unified Development Ordinance as follows:

PART 6. STORMWATER MANAGEMENT PLAN FOR NEW DEVELOPMENT

14.6.1. Purpose.

This part 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 in stormwater runoff. Specific objectives include: protection of riparian buffers, control of nitrogen export from development, control of peak stormwater runoff, and the use of best management practices.

This article shall apply within the Town and Town’s extraterritorial jurisdiction area.

(a) Establishment of Buffer All perennial and intermittent streams including lakes, ponds, and other bodies of water as indicated on the most recent version of the 1:20,000 scale (7.5 minutes) quadrangle topographic maps prepared by the United States Geological Survey (USGS) shall have a 100-foot wide riparian buffer directly adjacent to such surface waters, excluding wetlands. All other surface waters as indicated by the most recent version of the Soil Survey of Wake or Chatham County, North Carolina shall have a 50 foot-wide riparian buffer adjacent to such waters. In the Neuse River Basin, where obvious conflicts between actual field conditions and USGS and Wake county Soil Survey maps exist, appeals may be made to the North Carolina Division of Water Quality. All other appeals for obvious conflicts may be made to the Town Manager or his designee. Appeals to the 100-foot wide riparian buffer may be made as allowed by Section 14.6.8(a).

(b) Delineation of Buffer Zones. There are hereby established three zones of the riparian buffer as follows:

(1) Zone 1 (30’ landward adjacent to streambank, severe development restrictions)

(2) Zone 2 (20’ landward adjacent to) zone 1, strict development restrictions)

(3) Zone 3 (50’ landward adjacent to zone 2, moderate development restrictions)

The buffers must be measured horizontally from the edge of the water body, i.e. from top of bank.

(c) Activity within Buffer. Activity may take place within any stream buffer zone as defined by 15A NCAC 2B.0233. Likewise, those activities are also allowed within Zone 3.

Within the Neuse River Basin development activity within Zone 1 and Zone 2 of the may take place within a riparian buffer provided that the landowner has one of the following:

(1) An authorization certificate that documents that the NC Division of Water Quality has approved an allowable use.

(2) An opinion from the NC Division of Water Quality that vested rights have been established for that activity.

(3) A letter from the NC Division of Water Quality documenting that a variance has been granted for the proposed activity.

(d) Description of Buffers on Development Plans. Stream buffers shall be shown on all approved site plans and subdivision plans (see sections 5.6.5 (a)(2) and 5.7.3 application requirements).

(e) Exclusion of Buffer from Lots. No single family lots, created through a development plan, shall be platted into a riparian buffer as required by Chapter 14.1.4(m). The Town Council may allow buffers to be included in lots only when all of the following conditions are met:

(1) The buffer impacts a limited part of the subdivision (i.e., less than 10 lots);

(2) There is no other reason for the formation of a homeowners association (e.g., covenant, other common areas, …)

(3) The buffer is placed in a permanent conservation or other legal instrument dedicated to the Town (required documents must be provided prior to recording the plat for the impacted area).

(f) Exemptions. All single family residential lots platted prior to July 27, 2000 outside of the Neuse River 50 foot Riparian Buffer or residential subdivision plans submitted to the Town prior to July 27, 2000 whose lots are located outside of the 50 foot Neuse River Riparian Buffer shall be exempt from the requirements of this part.

(g) Enforcement. For violations of this part, refer to Chapter 14.1.15 (c).

(a) Definition of Development/Land Disturbance Nitrogen Control Plan Required. For purposes of this part, Nitrogen Control Plans shall be required for the following:

(1) Any activity that disturbs greater than one acre of land in order to establish, expand or modify a single family or duplex residential development or a recreational facility.

(2) Any activity that disturbs greater than 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 grubbing, stump removal and/or grading activity.

(4) Demolition and subsequent construction upon a previously developed site.

1. For purposes of this part, development shall not include agriculture, mining or forestry activities.
2. Existing development as of March 1, 2001 is not subject to the requirements of this ordinance. Expansions to existing development must meet the requirements of this ordinance. The impervious surface area of the existing development is not required to be included in the nitrogen load attributed to the site expansion; Nitrogen calculations must follow Town procedures for allocating undeveloped land to the site expansion proportionally based on the ratio of new impervious area to total impervious area.

(c) Vested Rights. Property owners that can demonstrate that they have vested rights, in accordance with Chapter 5, Part 13 of this ordinance, as of the effective date of this ordinance will not be subject to the requirements for new development.

Projects that require state permits, such as landfills, NPDES wastewater discharges, land application of residuals and road construction activities shall be considered to have vested rights if a state permit was issued prior to the effective date of this ordinance.

(d) Calculation of Nitrogen Export. The nitrogen export from each development must be calculated per Town procedures and approved by the Stormwater Manager or his designee. This export will be calculated in pounds per acre per year (lb/ac/yr). There are two different methodologies for calculating nitrogen export from development (refer to the Neuse River Basin: Model Stormwater Program for Nitrogen Control manual for calculating nitrogen export loading):

(1) Method 1 is intended for residential developments where lots are shown but the actual footprint of the buildings is not shown on the plans.

(2) Method 2 is for residential, commercial and industrial developments when the entire footprint of the buildings, parking lots, road and any other built-upon area is shown.

(e) Nitrogen Export Standards. All developments must achieve a nitrogen export of less than or equal to 3.6 pounds per acre per year. If the development contributes greater than 3.6 pounds per acre per year of nitrogen, then the table below explains the options available depending whether the development is residential or non-residential. The offset payment option shown below is only available for developments within the Neuse River basin.

Nitrogen Export Reduction Options

Once it has been determined that an offset payment is forthcoming, the owner shall furnish the Town with evidence that the North Carolina Division of Water Quality has received payment prior to the Town’s issuance of a grading permit.

For developments outside of the Neuse River Basin, the owner must provide evidence of intent to reduce nitrogen export to the levels required by this part to the maximum extent practicable.

There shall be no net increase in peak stormwater runoff flow leaving a development from pre-development conditions for the 1 year design storm. New developments are required to minimize damage to subject streams caused by storm flows.

(a) Calculation of peak flow. Acceptable methodologies for computing pre- and post-development conditions for the 1 year design storm include:

• The Rational Method (used when the drainage area is 200 acres or less)
• The Peak Discharge Method as described in USDA Technical Release Number 55 (TR-55) (drainage area is 2,000 acres or less)
• The Putnam Method (drainage area is greater than 2,000 acres)

The same method must be used for both the pre- and post-development conditions.

The following best management practices may be utilized for nitrogen reduction:

• Wet detention ponds
• Constructed wetlands
• Open channel practices
• Riparian buffers
• Bioretention
• Proprietary BMPs
• Others, as approved by the Town of Cary and the North Carolina Division of Water Quality

The total nitrogen (TN) BMP removal rates are provided in the table below.

BMP Types, TN Removal Rates and Design Standards

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 riparian buffer, then the removal rate shall be estimated to be 47.5 percent. The pond removes 25 percent of the nitrogen and discharges 75 percent into the buffer. The buffer then removes 30 percent of the nitrogen discharged from the pond, which is 22.5 percent. The sum of 25 and 22.5 is 47.5. The removal rate is not 25 percent plus 30 percent.

All best management practices that are implemented to achieve nitrogen reduction and peak flow attenuation will require complete legal documentation and a maintenance plan. For the purposes of this part refer to:

(1) Section 10.3.8 Engineered Stormwater Control Structures.

(2) Section 10.3.9 Posting Financial Security Required.

(3) Section 10.3.10 Inspections and Release of the Performance Bond.

(4) Section 10.3.11 Maintenance and Upkeep.

(a) Variances by Town Council. All requests for relief from the requirements of this part, only as they apply to Zone 3 of a riparian buffer within the Neuse River Basin or any riparian buffer within the Cape Fear River Basin, shall be decided by the Town Council in accordance with the requirements of Chapter 6, Part 1. Relief from the requirements of this part may also be permitted through the Planned Unit Development rezoning provided sufficient documentation is provided to meet criteria listed below. In addition, an applicant may apply for relief from the Zone 3 requirements of the 100-foot wide riparian buffer, notwithstanding the requirements of Section 10.3.12(a). Banking land within the same watershed may be required. The land to be banked shall have significant water quality value, such as being contiguous to an existing flood plain, wetland or riparian area. The land to be banked shall be preserved in a permanent conservation easement or other legal instrument whose provisions prohibit both farming and unapproved logging. This variance shall be based on documentation of practical difficulties or unnecessary hardships and documentation of the effects on water quality caused by development within the buffers as related to the following criteria. This documentation must include but not be limited to concept plan for the use of the site and data showing the impact on water quality.

(1) The basic project purpose cannot be practically accomplished in a manner that would better minimize disturbance and protect water quality

(2) The use cannot practically be reduced in size or density or redesigned to minimize disturbance and protect water quality

(3) BMPs will be used if necessary to minimize disturbance and protect water quality

(4) Impact to Zone 1 must be minimized to the maximum extent practical

(5) Compensatory mitigation must be done on a 1:1 ratio on a square foot basis for any impacts to Zone 1. This mitigation may consist of planting of an unbuffered area or additional planting of a partially buffered area located on-site or nearby

(6) The applicant must receive written approval from the Town Manager acknowledging that these conditions have been met before any impacts to the riparian buffer shall occur

If a Planned Unit Development (PUD) exceeds the open space requirement, the PUD may qualify for land banking.

(b) Variances Granted Only By the Environmental Management Commission: Only the Environmental Management Commission shall have the authority to grant variances from any other provisions of this Part.

This part is intended to provide for the enforcement of the Town's Storm Water Management Program; to prohibit non-storm water discharges to the Town storm sewer, require the removal of illicit connections to the Town storm sewer and prevent improper disposal of materials that degrade water quality.

This article shall apply within the Town and Town’s extraterritorial jurisdiction area.

The Town Manager or his designee is hereby authorized to enforce and administer the provisions of this article and other laws and regulations of the Town concerning storm sewers unless a contrary intention is expressed in such other laws and regulations.

It is unlawful for any person to empty or deposit in any storm sewer system in the Town, directly or indirectly, any substance, liquid or solid, which by reason of its nature, it:

(1) Is or may become a public health hazard endangering human or animal health.

(2) Is a nuisance, including substances which are unsightly or malodorous or may become so.

(3) Interferes or may interfere with free and rapid flow of surface water.

(4) Is inflammable or explosive.

(5) Is toxic to plant or animal life.

(6) Is corrosive or has properties which may damage or render unsightly the storm sewer system.

(7) Affects adversely the State of North Carolina classification of the stream into which the storm sewer system discharges.

It is unlawful for any person to place any obstruction in any storm sewer system in such a manner as to obstruct or impede the free flow of surface water. This section does not apply to the construction, reconstruction or alteration of storm sewer systems in manner consistent with sound engineering practices.

No person shall construct, repair or alter any storm sewer for the purpose of draining water from any land or premise unless he shall have first applied for and obtained therefore a permit from the Town Manager. The application shall be in writing and on a form provided by the Town Manager. The Town Manager shall issue the permit unless the Town Manager finds that the construction or repair work or alternations proposed would be contrary to the provisions of this article. The Town Manager may impose reasonable conditions upon the issuance of the permit to ensure compliance with this article which conditions may include, but shall not be limited to, specifications of the materials to be used and the manner in which the work or alteration is to be performed. It is unlawful for any person to perform any work or make any alteration for which a permit is required under this section except in compliance with said permit.

14.7.7 Inspection by Town Manager or designee.

Consistent with applicable law, the Town Manager or his designee is authorized to go upon private property for the purpose of inspecting storm sewer systems.

(a) The existence of any condition which obstructs or impedes the free flow of surface water contrary to the provisions of this article shall constitute a nuisance.

(b) Any condition which violates the provisions of section 14.7.4 constitutes a nuisance.

If the Town Manager finds any storm sewer system to be constructed, arranged, clogged or in such disrepair as to impede, obstruct or hinder the free flow of surface water in a manner which conflicts with acceptable engineering practices, he shall give notice in writing to the owner of the premises on which the condition exists to remedy the condition within such times as the Town Manager may reasonably prescribe. It shall be the duty of said owner to remedy or cause to be remedied the said condition within the time prescribed by the Town Manager, provided however, said owner may request an informal hearing before the Town Manager or his designee by giving written notice of such request to the Town Manager within the time prescribed by the Town Manager. The Town Manager or his designee shall fix the time and place for such informal hearing. A timely request for informal hearing made pursuant to this section suspends the requirements of the Town Manager’s earlier notice until the Town Manager or his designee issues a further notice subsequent to the informal hearing.

14.7.10 Violations; penalties.

(a) A violation of section 14.7.4 shall be a misdemeanor punishable in the manner prescribed by G.S. 14-4 for each separate violation.

(b) A violation of section 14.7.5 shall be a misdemeanor punishable in the manner prescribed by G.S. 14-4 for each separate violation.

(c) A violation of section 14.7.6 shall be a misdemeanor punishable in the manner prescribed by G.S. 14-4 for each separate violation.

(d) Any person who fails to comply with a notice issued by the Town Manager pursuant to section 14.7.10 shall upon conviction be guilty of a misdemeanor as provided by G.S. 14-4. Each day a person continues to fail to comply with said notice shall be a separate and distinct offense.

(e) Each day a violation prescribed under subsections (a), (b) and (c) of this section continues shall be a separate and distinct offense.

(f) This article may be enforced by any remedy prescribed by G.S. 160A-175.

Section 10.3.12 of the Cary Unified Development Ordinance is rewritten to read as follows:

10.3.12. Stream Buffers.

For the purposes of this rule, refer to Chapter 14, Part 6, 14.6.3 (a).

(a) In all developments under the High Density Option, a stream buffer of minimum width of 100 feet is hereby established along each stream located within the Reservoir Watershed Protection Districts. The width of each stream buffer, measured perpendicular to the banks of the stream, shall be equal to 100 feet on each side of the stream. For the purpose of this part high density option shall mean all development with an impervious surface coverage of 24% or more.

(b) No land-disturbing activities shall take place within any stream buffer, except for those facilities allowed by Section 14.6.3 (c). Nothing in this sub-section shall be construed to prevent desirable artificial stream bank shoreline stabilization.

(c) Stream buffers shall be shown on all site plans and subdivision plans (see Section 5.7.3).

(d) All principal buildings and structures and all accessory buildings and structures shall be set back from the stream buffer as required under Section 11.1.4.

(e) For violations of this part refer to Section 14.1.15(c).

(c) Fines and replacement of existing, original vegetation: Where the vegetation that has been disturbed or damaged existed on the site at the time the development was approved or installed at a later date, all replacement vegetation shall meet the standards set forth in this Section and/or Chapter 10. Part 1 and Part 3 taking into account any unique site conditions and significant vegetation remaining within the landscaped area. This Section shall also apply to all stream or riparian buffers and vacant, undeveloped properties that due to zoning conditions and/or requirements of the Thoroughfare Corridor Buffer District have protective vegetated areas and all requirements of Chapter 14, Part I, Building Design, Preservation of Existing Natural Areas and Installation of New Landscape Areas.

STREAM: A perennial or intermittent body of water running over the earth's surface in a channel or bed and is shown on the most recent version of the 1:24,000 scale (7.5 minute) quadrangle topographic maps prepared by the United States Geological Survey (USGS) and the most recent version of the Soil Survey of Wake County, North Carolina or Soil Survey of Chatham County, North Carolina

STORM SEWER SYSTEM: The system of catch basins, pipes (excluding residential rain gutters and downspouts), sewers, drains, culverts, open ditches, creeks and rivers which carry surface water and unpolluted water. A "storm sewer system" may be located on public or private property or both. (see Storm Drainage Facilities)

SURFACE WATER: Runoff from rainfall or ground watering which finds its way naturally into ditches and creeks.

PLANNING & ZONING BOARD RECOMMENDATION:

The Board voted (10 to 0) to forward to Council for approval at their February 14, 2002 meeting provided that Section 14.6.4 regarding vesting rights only applies to new development plans and that common law vesting would still apply to previously approved development plans.