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HomeMy WebLinkAboutWSMU_CARY_WSWP Ordinance_20230629 4.4.6 Watershed Protection Overlay (A) Purpose and Intent The intent of the Watershed Protection Overlay is to ensure the availability of public water supplies at a safe and acceptable level of water quality for present and future residents of the Town and the surrounding region.Watershed protection measures allowed by this section include: (1) Restriction of land uses allowed within water supply basins; (2) Impervious area and density limitations; and (3) Engineered stormwater control structures and the best management practices as listed in the Department of Environment and Natural Resources'State Design Manual. (B) Applicability (1) Designated Watersheds The Watershed Protection Overlay is an overlay district to be applied to all lands lying within the watershed of a public water supply.The boundaries of the Watershed Protection Overlay shall be shown on an official map kept in the Planning Department. The Watershed Protection Overlay consists of three sub-areas: (a) Swift Creek Watershed; (b) Jordan Lake Watershed; and (c) Jordan Lake Watershed Critical Water Quality Area. (2) Applicability to Development Activity (a) The following types of development activity are exempt from the requirements of this Section4.4.6: 1. Development existing prior to June 30, 1993; 2. Development on vacant lots inside of PDs approved prior to June 30, 1993; 3. Development on vacant lands in subdivisions platted prior to June 30, 1993, unless such lands have undergone a zoning change after June 30, 1993 and new development is required to submit a development plan; and 4. Redevelopment provided there is no increase in the total amount of impervious surface for a lot or developmentsite. (b) The requirements of this Section4.4.6 shall apply to the following: 1. Vacant land that is rezoned from its designation in place on June 30, 1993; 2. New lands added to a planned development after June 30, 1993, even if the original planned development was approved prior to June 30, 1993; 3. Development in a planned development if the development had to be amended after June 30, 1993, to accommodate the development; 4. Any expansions to existing development in place as of June 30, 1993 (provisions are only applied to the addition, not the impervious surface in place on June 30, 1993). (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 of this Ordinance. (C) Procedures for Development Approval (1) Development Review All development within the Watershed Protection Overlay shall demonstrate compliance with the requirements of this Section 4.4.6 at the time of approval of a development plan.Applicants complying with the standards of this section must also satisfy all other applicable requirements and obtain all other necessary approvals or permits under this Ordinance. (2) Protection Measures Prerequisite to Certificate of Occupancy A Certificate of Occupancy shall not be issued for anydevelopment in the Watershed Protection Overlay until all of the watershed protection measures required by this section have been approved and are in place on the property. (D) Overview of High Density and Low Density Development Options There are two(2)development options in the Watershed Protection Overlay, a Low Density Option and a High Density Option, each with different provisions related to either the Swift Creek Watershed or the Jordan Lake Watershed as well as to sub-areas within either watershed. (1) Impervious Surfaces The maximum allowable amount of impervious surface within a proposeddevelopment is limited based upon the Low or High Density Option, and differs from Watershed to watershed as depicted in Table 4.4-5. (2) Calculation of Impervious Surfaces Calculation of impervious surface area shall include the pavement area of all existing and proposed internalpublic and private streets, one-half(1/2)of the width of roadways on the perimeter of the project, driveways, rooftops, parking lots, patios, and all other impervious surfaces. For the purpose of calculating the impervious surface of roadways on the perimeter of a project,the ultimate pavement cross section of the roadway based on the Comprehensive Transportation Plan and any sidewalk(s)or greenway(s)along the perimeter roadway will be included in the calculation. For purposes of calculating the percentage of impervious area coverage, the total project area shall be regarded as the actual area of the property plus the area within the rights- of-way of the internal and perimeter streets included in the calculation of impervious area. (3) Residential Density In addition to limitations on the amount of impervious surface,the Low and High Density Development Options limit the gross residential densities of projects based upon the watershed where they are proposed,with higher densities allowed under the High Density Option as depicted in Table 4.4-5. (4) Runoff Control Engineered stormwater controls 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. (E) Restrictions on Allowed Uses The uses allowed within the Watershed Protection Overlay are the same as the uses permitted in the general use zoning district within which the land is located, pursuant to Table5.1-1. However,the following uses are allowed within the overlay district only if they comply with the performance standards set forth in this Section 4.4.6. (1) Swift Creek Watershed and the Jordan Lake Watershed (a) All industrial service uses; (b) All waste-related uses; (c) Uses producing and/or storing toxic and/or hazardous materials; and (d) Any use discharging sewage, industrial waste and/or non-process industrial waste. (2) Jordan Lake Watershed Critical Water Quality Area All uses set forth in paragraph (1)above; and all agricultural uses. (F) Limitations on Impervious Surface Area and Density (1) Low Density Option Maximum impervious surface limits for the Low Density Option are set forth in the table below. Separate regulations are provided for the Jordan Lake and Swift Creek areas. The Jordan Lake regulations recognize two sub-areas,the Critical Area and the remainder of the watershed;while the Swift Creek regulations distinguish between three(3)different sub-areas: New Suburban, New Urban, and Existing Urban development.These sub-areas are depicted on the Town's Official Zoning Map. TABLE 4.4-4:MAXIMUM IMPERVIOUS SURFACE LIMITS:LOW DENSITY OPTION Suburban-New Urban-New Existing Urban Residential Non-Residential Residential Non-Residential Residential and Non- Residential Swift Creek Watershed TABLE 4.4-4:MAXIMUM IMPERVIOUS SURFACE LIMITS:LOW DENSITY OPTION Suburban-New Urban-New Existing Urban Residential Non-Residential Residential Non-Residential Residential and Non- Residential Swift Creek Watershed Six(6.0)dwelling units per acre east of Holly Springs and Jones Two and one-half Franklin Roads, The impervious surface (2.5)dwelling units Greater than six(6.0) of the underlying zoning per acre not to units per acre west of of the property not to exceed twelve(12) Twelve(12)percent Holly Springs and Twelve(12)percent exceed twelve(12) percent impervious Jones Franklin Roads, percent impervious surface area. not to exceed twelve surface area. (12)percent, impervious surface area. Jordan Lake Watershed Impervious surfaces shall not exceed twenty-four(24)percent of the project area,or two(2)dwelling units per acre;or three(3) dwelling units per acre and thirty-six(36)percent impervious surface area for projects containing streets built without curbs and gutters. Jordan Lake Watershed Critical Area Non-residential and multi-family residential development's impervious surface ratios shall not exceed twenty-four(24)percent. Residential density(other than multi-family)shall not exceed two(2)dwelling units per acre. (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 Residential Non-Residential Residential and Non- Residential Swift Creek Watershed TABLE 4.4-5:MAXIMUM IMPERVIOUS SURFACE LIMITS:HIGH DENSITY OPTION Suburban-New Urban-New Existing Urban Residential Non-Residential Residential Non-Residential Residential and Non- Residential Swift Creek Watershed Six(6.0)dwelling units per acre east of Holly Springs and The impervious Two and one- Jones Franklin half(2.5) The impervious Roads.Greater area allowed The impervious area area allowed under under the dwelling units than six(6.0) allowed under the Maximum the underlying underlying per acre not to units per acre underlying general use Impervious general use zoning general use Surface Limits exceed thirty districts,not to west of Holly zoning districts, zoning districts,not to (30)percent Springs and exceed seventy(70) impervious exceed thirty(30) Jones Franklin not to exceed percent. surface area. percent. Roads,not to seventy(70) exceed seventy percent. (70)percent impervious surface area. Sewer Required Required to contain and treat the runoff from the first one(1)inch of rainfall and to achieve a minimum of Impoundment eighty-five(85)percent average annual removal for Total Suspended Solids(TSS).Public or private and maintenance.[Other BMPs besides impoundments may be available;consult the Department of Maintenance Environment and Natural Resources'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 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 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 Structures (1) Ownership and Design Requirements Stormwater control structures 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 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 Required for High-Density Option All development under the high-density option shall use engineered stormwater control structures as a primary treatment system. Engineered stormwater control structures shall be designed for specific pollutant removal according to modeling techniques approved by the North Carolina Department of Environment and Natural Resources. Specific requirements for these systems shall be in accordance with the Standard Engineering Details and Specifications Manual. (3) Ground Cover Required In addition to the vegetative filters required in the Standard Engineering Details and Specifications Manual, all land areas outside of the engineered stormwater control structures 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, 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 shall be prepared and filed consistent with Section 4.4.6(G)(9)as a separate deed with the Wake County Register of Deeds along with any easements necessary for general access to the stormwater control structure. 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 structure may be considered pervious when computing total built-upon area. However, if the structure 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 Wet detention ponds designed following the 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 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. 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 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 or 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 densitydevelopment 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 in accordance with the operation and management plan or manual provided by the owner.The owner of the stormwater control structure shall file the Operation and Maintenance Agreement with the Wake County 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 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 (a) The Stormwater Manager shall inspect the stormwater control structure 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 ready for filing with the Wake County Register of Deeds; 2. A certification sealed by a qualified professional stating that the stormwater control structure is complete and complies fully with the approved plans and specifications. 3. Reproducible as built plans showing best management practices. (b) The Stormwater Manager shall review the documents submitted by the owning entity and the Town's inspection report. 1. If the Stormwater Manager approves the inspection report, deed and easements, and accepts the certification,the owning entity shall file the Operation and Maintenance Agreement, deed and easements with the Wake County Register of Deeds and provide proof of recordation to the Stormwater Manager. Upon receipt of proof of recordation, the Stormwater Manager will issue a Certificate of Watershed Protection. 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 has approved the stormwater control structure, as provided in Section 4.4.6(G)(8)(b). (d) The owner of each stormwater control structure shall submit a Maintenance Inspection Report annually on the anniversary date of the Operation and Maintenance Agreement recording,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 of Environmental Management 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 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 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 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, 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 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 control structure is diminished or threatened, or to the extent of interfering with any easement or access to the stormwater control structure. (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.All improvements shall be made consistent with the approved plans and specifications of the stormwater control structure 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. (e) Amendments to the plans and specifications of the stormwater control structure 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 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 County 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 Clustering of development in the Watershed Protection Overlay may be allowed as an optional configuration in either Low Density or High Density developments on a project-by-project basis. Clustering shall follow the procedures and standards set forth in Section 8.4, and is subject to the following additional criteria: (1) The overall density and/or impervious surface coverage of the project may not exceed the density and/or impervious surface coverage allowed under either the Low Density or the High Density option.At a minimum, lot sizes shall conform to the standards of the TR district(see Chapter 6)for residential cluster development projects; however the total number of lots shall not exceed the number of lots allowed for residential subdivision development under any Chapter 4 zoning district; and (2) Impervious surfaces shall be designed and sited to minimize stormwater runoff impacts on the receiving waters and to minimize the concentration of stormwater flow; and (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 Register of Deeds. (I) Modifications and Variances Requests for relief from the requirements of this Section4.4.6 shall be decided either by the Zoning Board of Adjustment or by the Environmental Management Commission, depending on the watershed and the type of standard from which relief is sought. (1) Variances Granted by the Environmental Management Commission The Environmental Management Commission shall have the sole authority to grant major variances from the provisions of this Section 4.4.6 for properties in the Jordan Lake Watershed and Jordan Lake Watershed Critical Area. For purposes of this section, a major variance is a variance from the minimum statewide watershed protection or Jordan Rules(contained in 15A NCAC Chapter 2B)that results in (a)the relaxation, by factor greater than five percent(5%)of any buffer, density or built upon area requirement under the high density option; (b)any variation in the design, maintenance or operation requirements of a wet detention pond or other approved stormwater management system;or(c)relaxation by a factor greater than ten percent(10%), of any management requirement under the low density option. (2) Modifications Granted by the Zoning Board of Adjustment The Zoning Board of Adjustment shall have primary, but not sole, authority to grant modifications from the provisions of this Section 4.4.6 for properties in the Swift Creek Watershed, pursuant to this Sub-section. (a) In the Swift Creek Watershed,the Zoning Board of Adjustment may modify the standards of Section4.4.6(F), Limitations on Impervious Area and Density,where using perimeter or adjacent roadways in the impervious surface calculation causes a development to exceed the allowed impervious surface percentage. (b) In the Swift Creek Watershed, the Zoning Board of Adjustment may modify the standards of Section4.4.6(F), Limitations on Impervious Area and Density, to allow impervious surface ratios greater than twelve(12) percent but less than twenty-four(24) percent. However, requests for relief greater than twenty-four(24)percent shall be forwarded for review and decision by the Environmental Management Commission. (3) Recommendation by Zoning Board of Adjustment to the Environmental Management Commission If an application calls for the granting of a modification as listed in paragraph (2b)or paragraph (1)above that requires a decision by the Environmental Management Commission,the Zoning Board of Adjustment shall first reach a recommendation on the modification in accord with the requirements of Section 3.19. If the Zoning Board of Adjustment decides in favor of granting the modification, the Zoning Board of Adjustment shall prepare a preliminary record of the hearing as soon as possible and forward it to the Environmental Management Commission.The preliminary record of the hearing shall include: (a) The modification application; (b) The hearing notices; (c) The evidence presented; (d) Motions, offers of proof, objections to evidence, and rulings on them; (e) Proposed findings and exceptions; (f) The proposed decision, including all conditions proposed to be added to the permit. (4) Decision by the Environmental Management Commission (a) Approval If the Commission approves the variance as proposed or with additional conditions,the Commission shall prepare a decision and send it to the Zoning Board of Adjustment. The Zoning Board of Adjustment shall prepare a final decision in accordance with the Commission's decision. (b) Disapproval If the Commission denies the variance as proposed the Commission will prepare a decision and send it to the Zoning Board of Adjustment.The Zoning Board of Adjustment shall prepare a final decision in accordance with the Commission's decision. (J) Violations; Enforcement This Section 4.4.6 shall be enforced by the Town Manager or designee.Any person or association who fails to comply with any provision of this Section 4.4.6, or who fails to submit a report, or who submits a fraudulent or false report, shall be in violation of this Ordinance for each occurrence or non-compliance.