The following minimum standards shall apply to earth moving and land-disturbing activity which is not otherwise exempt.
(A) Minimum alterations. Earth moving shall be limited to the minimum required for building foundations, driveways and drainage control structures, and immediate areas surrounding the building, structure, road, driveway or drainage structure required by this chapter. With the exception of approved stockpiling or restoration efforts, substantial earth moving beyond that which is required for the installation or construction of approved buildings, structures, driveways, roads or drainage structures shall not be permitted.
(B) Cut and fill. Unless otherwise specifically approved by the Director and a registered professional engineer, cut slopes shall be no steeper than one foot horizontal to one foot vertical (one:one) and fill slopes shall not be steeper than one-and-one-half feet horizontal to one foot vertical, except in circumstances where stable exposed rock is the intended end result of the manufactured slope and/or when sufficient evaluation is provided to support stabilization by a professional engineer registered in the state. Manufactured slopes exceeding 35 feet in height shall be benched at 35-foot intervals. Reforestation of manufactured slopes other than stable exposed rock shall consist of the placement of native species in a plan prepared by a professional landscape architect or arborist familiar with steep slopes and stabilization requirements. A maintenance plan shall be required for reforestation areas and the plan shall include provisions for replacement of dead vegetation when greater than a 30% mortality rate occurs.
(C) Compaction of fill. All fill shall be stabilized in conformance with generally accepted engineering standards, including a compacted density of at least 95%. Vegetation which has been cut or cleared shall be removed from the site and shall not be covered by, or imbedded in, fill material. Extra care shall be taken in removing the woody and/or vegetative debris from fill materials, as it has been found and shown by the State Geological Survey that the material can increase the probability of slope destabilization and lead to such events as an embankment failure or other such earth moving phenomenon. The Director may require certification of compaction by a qualified professional if necessary to determine compliance with this section.
(D) Control of stormwater runoff. Runoff from concentrated impervious surfaces shall be collected and transported in a pipe or other approved manner to an approved storm water system if available, or if unavailable, to the bottom of the drainage way or other location specified by the Director and/or a registered professional engineer and in a safe, adequate, and non-erosive manner. Where required by other ordinances or regulations or by an engineer, storm water retention facilities shall be installed. Where required, interceptor ditches shall be established above steep slopes in such a way as not to avoid saturation or erosion of soil, and intercepted water shall be conveyed in a pipe or other manner to the bottom of the drainage way or other location specified by an engineer. The overall drainage system shall be completed and made operational at the earliest possible time during construction. The proposed storm water control system shall utilize the principles and recommendations of the State Department of Environment and Natural Resources Stormwater Best Management Practices ("BMPs") Manual. Specifically, the methods of storm water management chosen, shall take into account the compatibility of the method with steeper slopes, applicable depth to the water table, soils present and the expected amount of sediment. Careful control of stormwater runoff and other surface waters is critical for the stability of steeply sloped lands. Marginally stable land can be rendered unstable by the increased pore pressure due to infiltrating water. So, while it is encouraged to retain and help storm water infiltrate the ground on site, it is important that proper analyses show the proper location on a site for that infiltration to take place. As a general rule of thumb, when an entire site is comprised of steeper slopes, it may be necessary to use a variety of smaller BMPs to fit the contours of the subject site. For proposed developments that are governed by this chapter, a comprehensive storm water management plan shall accompany the submitted application. The proposed method of managing storm water shall utilize appropriate site specific mitigation and structural practices to effectively provide no net increase in storm water runoff versus pre-development conditions.
(E) Stream and wetlands protection. It is recognized that areas of steep terrain produce higher amounts of storm water runoff at higher velocities. Development on those areas will only contribute to that trend. The direct discharge of the storm water to local drainage ways and wetlands can have significant negative effects on the quality of the waters within the drainage way or wetlands and the diversity of wildlife that the areas can sustain. While efforts are to be made to properly control and manage the runoff, there is no substitute to a stream's or wetland's health for the role of a riparian buffer. As such, a riparian buffer shall be provided by the developer and/or protected by the developer for all perennial and intermittent streams and wetlands. The buffers shall extend a minimum of 50 feet from the center line of a stream and 50 feet from the edge of any wetlands areas. See the below figure: All required riparian buffers shall be included as common areas within a development, instead of being included within the boundaries of individual lots. No land-disturbing activity may take place within the required stream or wetlands buffer except for approved street crossings. However, an encroachment into the required stream or wetlands buffer may be allowed at the discretion of the Town Council. The Town Council shall take into account the recommendation of town's staff in granting or denying an encroachment. There are multiple examples of when such an encroachment might be granted. For example in certain instances the allowance of a roadway within the buffer zone may prevent large cut and fill and tree clearing operations further uphill of the stream or wetlands, especially if logging roads or some other pre-defined path exists within the prescribed stream or wetlands buffer. In such a case, the allowance of an encroachment may do more to protect the health of the stream or wetlands than adhering to the prescribed buffer requirement contained herein. The siting of a stormwater management facility may be optimal within a stream buffer due to soil conditions, slope conditions, the necessity to treat stormwater runoff before the runoff enters the applicable stream or wetlands, or some other characteristics. In this case, it may be more appropriate to allow an encroachment of the required stream buffer as well. In order for such an allowance to be granted, the applicant shall demonstrate to the Town Council that such an encroachment will be within the intent of this § 156.26(E) below, and will benefit the stream's health more so than strict adherence to the prescribed stream buffer requirement. In the case where impervious surface is allowed within the stream buffer, the impervious surfaces shall not count towards the buffer width and so additional width shall be added to the buffer in order to comply with this division (E). All proposed ponds and/or lakes shall be built outside of stream channels. When built in-line (within stream channels) , ponds and lakes pose many negative impacts to local streams.
(F) View-sheds. It is recognized that the scenic and aesthetic qualities of the mountains and hillsides in this region play an important role in the economy and the quality of life for residents within the community. As such, whenever a building is to be constructed which is governed by this chapter, its building and grading envelope shall be sited so that the structure to be placed thereon shall not be readily visible from public rights-of-way or public lands, the elevation of which is equal to or less than the structure. This may be accomplished through natural terrain, existing vegetation, or some other means consistent with accepted industry standards and approved by the Director. Views of the surrounding mountains from prominent state roads, such as N.C. 108, which generate significant amounts of traffic, shall especially be considered.
(G) Building height. The height of any building shall not extend closer than 50 feet to the uppermost point of any protected mountain ridge, as that term is defined herein, on which the building is constructed. Nor shall any building be constructed closer than 20 feet to the shoulder of any protected mountain ridge. See § 156.28(R) for more information on construction near and around the shoulder of a ridge). For the purposes of this chapter, the uppermost point of the crest, summit or ridge top refers to geological formations and not vegetation. Items, such as chimneys, flues, flag poles and wires may be allowed to extend to within the 50-foot setback only at the Director's discretion.
(H) Disturbance limits. No more than 20 acres may be disturbed at one time throughout the course of a development. If 20 acres is currently being disturbed, then all or a portion of that 20 acres must be re-stabilized before continuation of the project to other land disturbing activities within the tract.
(I) Impact on neighboring properties. Any negative externalities generated by a development shall be remedied at the expense of the party(ies) financially responsible for the development. As an example, if a stream is polluted by sediment washing off of a development, then the party responsible for creating the erosion shall incur the cost of repairing the stream. If such a situation arises, then the final plat of a development or phase of development shall not be approved until a written plan of remediation has been submitted to the town and corrective work has commenced. Depending on the scope of the repair work, a monetary surety of completion may be required.
(J) Realignment of streams. Realignment of streams and natural drainage channels shall not be permitted except for the purpose of affecting a stream crossing and only as specifically approved by the Director upon issuance of all necessary state and federal permits. In such cases, natural or typical flow of surface or subsurface water shall not be altered or obstructed in any way by grade changes if the alteration may adversely affect the property of another by either contributing to pooling or collection of waters, the increased deposition of sediment into neighboring waterways and/or lands, or to the concentration or intensification of surface water discharge.
(K) Impervious surface limits. Development on lands that are subject to this chapter shall meet the impervious surface and grading requirements shown in the table below.
Average Slope of Land to be Developed or Subdivided | Maximum Amount of Grading | Maximum Amount of Impervious Surface |
20% - 25% | 50% | 10% |
26% - 30% | 40% | 8% |
31% - 35% | 20% | 4% |
36% - 40% | 10% | 2% |
> 40% | 5% | 1% |
NOTE: These grading requirements shall not be construed to allow a violation of the town land Clearing, Grading and Tree Protection Ordinance. | ||
(L) Density limits.
(1) Development on lands that are subject to this chapter shall meet the density requirements shown in the appropriate table below.
Maximum Density for Developments with Public Water and Sewer Systems | |
Average Slope of Land to be Developed or Subdivided | Maximum Density (Lots per Acre) |
20% - 25% | 0 . 50 |
26% - 30% | 0 .33 |
31% - 35% | 0 .20 |
36% - 40% | 0 . 13 |
>40% | 0 .08 |
Maximum Density for Developments with Private Water or Single Family Wastewater Treatment and Disposal Systems, But Not Both | |
Average Slope of Land to be Developed or Subdivided | Maximum Density (Lots per Acre) |
20% - 25% | 0.40 |
26% - 30% | 0 . 24 |
31% - 35% | 0 .13 |
36% - 40% | 0 . 07 |
>40% | 0 . 05 |
Maximum Density for Developments with Private Water and Single Family Wastewater Treatment and Disposal Systems | |
Average Slope of Land to be Developed or Subdivided | Maximum Density (Lots per Acre) |
20% - 25% | 0 .25 |
26% - 30% | 0 . 14 |
31% - 35% | 0 . 08 |
36% - 40% | 0.05 |
>40% | 0.04 |
(2) Whenever a conflict arises in the allowable density of a development or minimum lot size as determined by this Mountain and Hillside Development Ordinance, the town Zoning Ordinance, or the town Subdivision Ordinance, the more restrictive regulation shall apply.
(M) Recognition. Developers that undertake exemplary developments that provide housing and/or commercial opportunities to the town while protecting view-sheds, avoiding habitat fragmentation, and protecting water quality shall be recognized as good stewards of the region's resources. It is the intent of this division to promote quality development and careful site design. Therefore, those that utilize the practices shall be granted a certificate from the town attesting to the quality of such a developer's work. Recognition of the developer's integrity and quality will also be posted on the town's official web site. Both the certificate and the web site posting may be used for the purposes of marketing the developer's services.
(N) Determining slope. The following shall offer guidance and procedure for the purposes of calculating slopes for parcels, tracts and/or slope districts.
(1) Prior to commencing any development or land-disturbing activity and prior to making application for any permits and/or other approvals, the calculated average slope for a particular land tract shall be approved by the Director. Average slope calculations and supporting documentation shall be submitted to the Director for review. Within ten days of receipt, the Director shall: request additional information; request revisions to the average slope calculation submittal; or issue written concurrence with the determination of average slope, as submitted.
(2) It is recognized that one average slope calculation may not be suitable for analyzing larger tracts of land that are proposed to be developed. As such, tracts of land that are proposed to be developed and are greater in size than 20 acres shall be broken down into smaller divisions. These smaller divisions of land shall be referred to as slope districts. When an application is submitted for a land-disturbing activity regarding a project that is greater than 20 acres, the submitted slope calculations shall be for each created slope district. The applicant may arrange these slope districts in a manner suitable to him or her so long as any given slope district does not exceed 20 acres in size, the borders are contiguous with one another, and the borders coincide with proposed lot lines, the tract boundary, or the boundary of any delineated open space area. The slope districts shall exclude any areas proposed to be dedicated open space. For each slope district:
(a) Calculate each slope district's percent slope according to § 156.25(N)(7) below;
(b) Find each district' s corresponding percent impervious surface, density and grading limits based on the calculated slope in accordance with the tables found in divisions (K) and (L) above;
(c) For each requirement (i.e. density, grading and impervious surface) multiply the result of (ii) above by the number of acres within the slope district. This will give the actual amount of impervious surface, grading and lots allowed per slope district; and
(d) Add the outcomes of division (c) above, for each slope district together. This will give the total limit for each requirement (i.e. density, grading and impervious surface) for the entire site.
(3) Each slope calculation submitted to the Director for review shall include a scaled map, accurately showing (a) topography for the entire land tract, (b) a closed perimeter line delineating a single area proposed for the occurrence of any type(s) of land-disturbing activity , (c) the deeded land tract boundary, and (d) the boundaries of any slope districts. The accuracy and detail of the map shall be acceptable to the Director for site specific conditions and the particular land disturbing activities proposed.
(4) Tracts of land greater than 20 acres. When a tract of land is proposed for any type of land-disturbing activity and the subject tract of land is greater than 20 acres, the applicant shall divide the tract into slope districts. The submitted slope calculation shall contain an average slope for each slope district.
(5) Tracts of land equal to or less than 20 acres. When a tract of land is proposed to be developed and is less than or equal to 20 acres in size, an average slope calculation shall be submitted for the entire tract.
(6) Single-family dwellings and two-family dwellings. The slope calculation submitted with an application for the construction of a single-family or two-family dwelling project only needs to incorporate the areas of land within the proposed building and grading envelope.
(7) Slope calculation preparation. The submitted slope calculation shall be prepared by a professional land surveyor, engineer, architect or other approved professional that is registered in the state. If such a professional does not prepare the submitted calculation, then the town's Planning Department shall keep a slope database in its GIS system and shall use the highest slope contained within the proposed tract of land to determine the slope of the tract for the purposes of administering the regulations contained within this chapter.
(8) Slope calculation submittal. When a slope calculation is submitted, the methodology used by the approved professional, responsible for creating the calculation shall be submitted as part of that slope calculation submittal.
(O) Hazardous waste facilities. Handling areas for the receiving and storage of hazardous waste or solid waste disposal facilities are prohibited in areas regulated by this chapter.
(P) Mining. Mining activity which requires a new permit from the State Department of Environment and Natural Resources shall be prohibited in the areas regulated by this chapter. Expansion of an existing mining activity that would require a permit modification from the North Carolina Department of Environment and Natural Resources shall be prohibited in the areas regulated by this chapter.
(Q) Antennas and towers. Water, radio, television, cell or other towers shall not extend more than 40 feet, as measured from the highest point at which the foundation of the structure intersects the natural ground surface, above the uppermost point of the crest, summit, or ridge top of the protected mountain on which the structure is constructed.
(R) Division of area. Where there is a drastic variation in the landform character within one site, the site may be divided into several distinct areas for the purposes of slope determination. This division must be approved by the Director. Generally, this provision shall only be used in cases where large tracts of property encompass flat land as well as significant mountain and hillside terrain. Details for each division must be provided.
(S) Landslide hazard advisory. The following statement shall be recorded on the final plat with the Polk County register of deeds for any lot created whose surface slope is equal to or greater than 20%: "While landslides and other slope moving events have occurred as a result of less precipitation, storm events that produce five inches of rainfall during a 24-hour period significantly increase the risk of landslides on areas of 20% slope or more. Slopes that have been modified with excavations, embankments, and/or structures are at higher risk of earth movement than unmodified/natural slopes."
(T) Lot design. All water supply sources and conveyance systems and all wastewater conveyance, treatment, disposal and reuse systems, if any, shall be sited prior to or in conjunction with lot layout in order to ensure adequate space is provided for each system. While this is preferred for all developments, it is especially important to consider well and septic considerations on steeper terrain as such topography will usually mandate the provision of greater space for each system.
(U) Ground water monitoring. Developments regulated by this Mountain and Hillside Development Ordinance that propose to use groundwater for any reason, to include non-potable uses, shall initiate a well monitoring program. The program shall provide for the monitoring of all wells on site at a minimum of once every three years. A site specific groundwater monitoring plan shall be described in detail and shall be submitted as part of the hydro-geological report required by § 156.11(C)(4). The groundwater monitoring plan shall include the monitoring of ground water levels as well as those regulated and unregulated contaminants defined by the Environmental Protection Agency (EPA) and the State Department of Environment and Natural Resources' Public Water Supply Section. A groundwater monitoring plan shall not be required if the proposed development is not proposed to extract more groundwater than 6,000 gallons per day (four gallons per minute).
(V) Conservation design. All subdivisions regulated by this chapter shall utilize the town Subdivision Ordinance's clustering option. The clustering of structures shall be located on flatter and less sensitive lands, while preserving steep, more sensitive, and more fragile lands as open space.
(W) Golf courses. No development regulated by this chapter shall be provided with a golf course.
(X) Grading contractor selection. The grading contractor selected to work within a development governed by this chapter shall have either completed an accredited formal certification program or have completed the Clear Water Contractor© program. A list of grading contractors that have completed the Clear Water Contractor© program since 1999 can be found at www.themayberrygroup.org.
(Ord. passed - -2008)