3.3.2-A Critical Areas (CA-1, CA-2, CA-3, CA4)

Intent: The intent of these regulations is to require higher standards in the Critical Areas of the Mountain Island Lake Watershed because of the greater risk of water quality degradation from pollution. All uses permitted in the Critical Areas are subject to the standards of both the overlay district and the underlying zoning district. In every case, the more restrictive standard controls.

a) Permitted Uses

Uses permitted with conditions

  • essential services 1 and 2, provided that there shall be no new industrial process or domestic discharges into any stream or lake in the Mountain Island Lake Watershed, but existing wastewater treatment plant(s) may expand so long as the total pollutant load per parameter is not increased beyond the effluent limits permitted as of October 1, 1993, the effective date of watershed protection regulations;
  • agriculture, subject to the provisions of the Food Security Act of 1985 and the Food, Agricultural, Conservation and Trade Act of 1990. All agricultural activities conducted after January 1, 1993 shall maintain a minimum ten foot vegetative buffer, or equivalent control as determined by the Soil and Water Conservation Commission, along all perennial waters indicated on the most recent versions of U.SG.S 1:24,000 scale topographic maps or as determined by local government studies. Agricultural activities begun after October 1, 1993 shall comply with the buffer standards of Section 3.3.3 -A(f). Animal operations greater than 100 animal units shall employ Best Management Practices by July 1, 1994 recommended by the Soil and Water Conservation Commission;
  • silviculture, subject to the provisions of the Forest Practices Guidelines Related to Water Quality (15A NCAC1T.0201-.0209);
  • residential uses permitted in the underlying district, subject to density and built-upon limits of the low density development option; cluster development allowed in the underlying district is permitted;
  • non-residential uses permitted in the underlying district, subject to the built-upon limits of the low-density development option; cluster development allowed in the underlying district is permitted.

b) Prohibited Uses

  • all uses not permitted in the underlying zoning district
  • residual applications
  • landfills, sanitary
  • landfills, off-site demolition
  • new or expanded domestic and industrial discharges
  • structural BMPs not associated with agriculture
  • disposal or treatment of petroleum contaminated soils (land farming)

c) Permitted Building and Lot Types

  • building and lot types permitted in the underlying zoning district

d) Permitted Accessory Uses

  • accessory uses permitted in the underlying zoning district; uses prohibited as principle uses are also prohibited as accessory uses

e) Built-Upon Area Development Standards

For individual buildings or for development projects within the Critical Areas, the following impervious area limitations are established on a building or project basis.                              

Area
Percent
 CA1
 6% B.U. 1
 CA2
 12% B.U. 1
 CA3
 12% B.U. 1
 CA4
 24% B.U. 1

1 Residential subdivisions approved after 2/17/03 shall reserve, at minimum, 1% of the lot area but in no case less than 150 square feet impervious area per lot to allow for addition of future impervious areas by homeowner/occupant

f) Buffer Size

Undisturbed buffers, except as specifically provided in this section, are required in the Critical Areas along the shoreline of Mountain Island Lake, measured horizontally by a licensed land surveyor from the normal pool elevation (648’ contour), and along all perennial streams, measured from the top of the bank on each side of the stream.                                                

Area
Feet
 CA1
100 feet or 100 year flood plain boundary, whichever is greater
 CA2
100 feet or 100 year flood plain boundary, whichever is greater
 CA3
100 feet or 100 year flood plain boundary, whichever is greater
 CA4 (lake shore)
100 feet


g) Buffer Protection

No permanent structures, impervious covers, septic tank systems or any other disturbance of existing vegetation shall be allowed within the buffer except as follows:

1) The surveyed buffer boundary must be clearly marked on-site with orange “tree-protection” or “high-hazard” fence prior to any land disturbing activities. Tree protection is required by Section 7.4(3) of this Ordinance.

2) The surveyed buffer boundary must be permanently marked with an iron pin at the intersection of the watershed buffer and each property line following the completion of land disturbing activities and prior to occupancy. Properties greater than 200’ in width shall be marked at a maximum of 100’ intervals.

3) No trees larger than 2-inch caliper, measured at 6 inches above the existing grade, are to be removed except for dead or diseased trees. Undergrowth and trees less than 2-inch caliper, measured at 6 inches above the existing grade, may be removed to be replaced by an effective stabilizing and filtering ground cover based upon the most recent edition of the “Watershed Buffer Guidelines for Mecklenburg County, NC” and as approved by the Mecklenburg County Water Quality Program.

4) Stream bank or shoreline stabilization is allowed as approved on a plan submitted to the Town Engineering Department and the Mecklenburg County Water Quality Program.

5) Water dependent structures and public projects such as road crossings and greenway paths are allowed where no practical alternatives exist. These activities should minimize built-upon area, direct runoff away from surface waters, and maximize the utilization of nonstructural BMPs and pervious materials.

6) During new development or the expansion of existing development, the Town, upon the advice of the Mecklenburg County Water Quality Program, can require enhancement of the existing vegetation in the buffer if necessary so that the buffer can effectively perform its filtering and absorption functions. Buffer enhancement requirements shall be based on the most recent edition of the “Watershed Buffer Guidelines for Mecklenburg County, NC.”

7) Mitigation of disturbed buffers required. Should existing vegetation within the buffer be disturbed (except as allowed by this Ordinance) or should vegetation added to a buffer pursuant to paragraph 6) be disturbed, the property owner shall be required to enhance the buffer in accordance with the most recent edition of the “Watershed Buffer Guidelines for Mecklenburg County, NC” so that the buffer can effectively perform its filtering and absorption functions.

8) Non-impervious recreational development and non-impervious pedestrian trails are allowed in the required buffer in compliance with paragraph 3), above. Pathway guidelines are available in the most recent edition of the “Watershed Buffer Guidelines for Mecklenburg County, NC.” If in a common area, such development and trails must be located a minimum of 30 feet from the normal pool elevation of Mountain Island Lake (648’ contour), or a minimum of 30 feet from the top of the bank on each side of all perennial streams; except for waterfront access points approved by the Town, upon the advice of the Mecklenburg County Water Quality Program.

9) Non-conforming structures and increasing built-upon area may permitted if the following criteria are met:

a. The existing structure (to be expanded) was built prior to the enactment of the 1993 watershed ordinance.

b. The Built-upon area (BUA) of the existing structure must cover a minimum of 10% of the 100-foot buffer on the lot.

c. In Critical Area 1 (CA1), which has a 6% BUA cap, the maximum allowable increase in BUA in the buffers is 2%. In Critical Area 2 (CA2) and Critical Area 3 (CA3), which have a 12% BUA cap and Critical Area 4 (CA4), which has a 24% BUA cap, the maximum allowable increase in BUA is the buffer is 4%.

d. Existing BUA shall not be increased within the State minimum 50-foot buffer.

e. Best Management Practices (BMPs) (including rain gardens and plantings) must be installed to achieve the following removal efficiencies for all BUA on the lot (not just the BUA in the buffer):

i. 85% removal of Total Suspended Solids (TSS)

ii. 60% removal of Total Phosphorus (TP) f. All BMPs shall be installed or planted in accordance with the Charlotte-Mecklenburg BMP Design Manual and in accordance with Huntersville’s Water Quality Ordinance.

g. Maintenance Agreements and Maintenance Plans must be recorded for all BMPs installed and/or planted and the location of the BMP and corresponding notes must be recorded on the deed in compliance with Huntersville’s Water Quality Ordinance.

h. Mitigation measures, including all BMPs, must be installed, inspected and approved and the provisions described in item g (above) satisfied prior to the release of any certificates of occupancy for the structural expansion.

i. All structural BMPs must be inspected and certified annually for compliance with design criteria by a licensed NC. engineer in accordance with the Huntersville Water Quality Ordinance. Inspection reports must be submitted to Mecklenburg County for approval.

j. Any deficiencies detected to the BMP or any other mitigation measure must be corrected within 30 days of detection at the sole expense of the property owner. Failure to do so will be in violation of the Huntersville Water Quality Ordinance and could result in the assessment of penalties.

h) Paired-Parcel Averaged-Density Development

The transfer of impervious development rights between two (2) parcels not within the boundaries of the same subdivision by way of designated undisturbed natural areas. A metes and bounds description of the space to be undisturbed and limits on use shall be recorded on the subdivision plat, in homeowner covenants, and on individual deed and shall be irrevocable. The resultant impervious area/amount for the two lots combined shall not exceed the original allowable impervious amount for each individual lot if they were developed separately.

  • A density averaging certificate shall be considered one development request.
  • Overall impervious area/amount of the paired parcel averaged-density development, calculated by built-upon area, shall not exceed the impervious that would be allowed if the parcels were developed separately. The parcel pair shall be located in the same water supply watershed and preferably in the same drainage area of the watershed. Parcel pairs may be located in the Critical Area and in the Protected Area. However, if one of the parcels is located in the Critical Area and one is located in the Protected Area, the Critical Area parcel shall not be developed beyond those impervious amounts allowed in the critical area provisions of the Huntersville Zoning Ordinance. A property in a more restricted watershed area shall not acquire impervious rights from a property in a less restricted area of the watershed. The purpose of this provision is to preserve open space in the more sensitive areas of the watershed.
  • The paired parcels may include or be developed for residential or non-residential purposes.
  • Buffers shall at least meet the appropriate minimum Huntersville Zoning Ordinance water supply watershed protection requirements on both parcels in the parcel pair.
  • The portion of the parcel(s) which is not developed as part of the paired parcel, but that is being averaged in the land area being evaluated to meet the built-upon surface area, shall remain in an undisturbed vegetated or natural state. A metes and bounds description of the space to be undisturbed and limits on use shall be recorded on the subdivision plat, in homeowner covenants, and on individual deed and shall be irrevocable. The resultant impervious area/amount for the two lots combined shall not exceed the original allowable impervious amount for each individual lot if they were developed separately. It shall be noted on the plat that the Zoning Administrator shall reserve the right to make periodic inspections to ensure compliance.
  • A Density Avenueraging Certificate shall be obtained from the Watershed Review Board (Board of Adjustment) to ensure that both parcels considered together meet the standards of the ordinance and that potential owners have record of how the watershed regulations were applied to the parcel pair. Only the owner(s) of both of the paired parcels may submit the application for the Density Avenueraging Certificate. A site plan for both of the parcels must be submitted and approved as part of the Density Avenueraging Certificate. If such a certificate is granted, no change in the development proposal authorized for either parcel shall be made unless the certificate is amended. Upon issuance of such certificate, one copy will be forwarded to the North Carolina Division of Water Quality (DWQ). Included with the Density Avenueraging Certificate will be a site plan, registered plats for both properties, a description of both properties, and documentation reflecting the development restrictions to the parcel pair that will remain undeveloped.
  • The Watershed Review Board shall make written findings supported by appropriate calculations and documentation that the paired parcel averaged-density development plan as a whole conforms to the intent and requirements of this Article and Section, and that the proposed agreement assures protection of the public interest.
  • The undisturbed land area shall be recorded in the deed for the parcel to which it applies. The Density Avenueraging Certificate shall be recorded in the deed for each of the parcels in the parcel pair. Both the designated undisturbed land area and the certificate shall be noted on the subdivision plat that applies to each of the parcels.
  • Stormwater runoff from paired parcel averaged density-averaged development which meets the low-density option development requirements shall be controlled by vegetative conveyances to the maximum extent practicable and shall be approved by Mecklenburg County Storm Water Services’, Water Quality Program.
  • Stormwater runoff from paired parcel averaged density development which meets the high-density option development requirements shall be controlled on the parcel(s) where the high-density development is occurring in accordance with the criteria specified in the Huntersville Water Quality Design Manual and the Huntersville Zoning Ordinance for high-density development.
  • No parcel for which a watershed variance has been granted, or would be required, may be included as part of a parcel pair.
  • Compliance with criteria 1-12 shall be evidence that the parcel pair is consistent with the orderly and planned distribution of development throughout the watershed.

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