ARTICLE V. STEEP SLOPES (3/08)
1. Purpose and Intent
As recognized in its Master Plan (2006), the Town of Holderness' lakes, mountains, hillsides, woodlands, streams, wetlands and scenic views are important elements of the quality of life for residents, other property owners, and visitors. The nature of the soils on steep slopes in the Town of Holderness is such that the land is exceptionally vulnerable to erosion and associated problems. Therefore, in order to protect the public health, safety and welfare of individual landowners, owners of abutting property and the Town of Holderness, this article is intended to guide the use of steeply sloping land within the town. The purposes of this article include: (a) to reduce damage to streams, lakes and groundwater from the consequences of excessive or improper construction, erosion, storm water runoff, or effluent from improperly
sited or designed sewage disposal systems, (b) to preserve the natural topography, drainage patterns, vegetative cover, scenic views and wildlife habitat, (c) to protect unique natural areas, and (d) to provide reasonable access to properties for fire, public safety, or other emergency crews.
2. Delineation
This article shall apply to all areas that include a slope equal to or greater than 15 percent (Steep Slopes Protection Area), as shown on the town's steep slopes map. The steep slope Application Requirements, Performance Standards and Design Guidelines apply only to the area of site disturbance. If an area is incorrectly identified on the map as having steep slopes, the provisions of this article shall not apply. Conversely, if an area is found to have steep slopes and is not identified on the map, the provisions of this article shall apply. The final determination of a steep slopes area shall be made by the Board of Selectman or its agent, who may have prepared a site-specific survey at the applicant's expense to make the determination.
3. Definitions - See Article XIII
4. Application Requirments
A. Sediment and Erosion Control Plan
A Sediment and Erosion Control Plan will be prepared by a New Hampshire licensed professional engineer that shows specific methods that will be used to control soil erosion and sedimentation, soil loss, and excessive storm water runoff, both during and after construction (Article IV.B.3, Removal of Natural Material - Steep Slopes).
B. Site Grading Plan
A Site Grading Plan for the construction site and all access routes will be prepared by a New Hampshire licensed professional engineer or surveyor. Uses that will cause more than 15,000 square feet of site disturbance must show the area subject to site disturbance in two-foot contours. The area to be disturbed should be clearly delineated relative to the proposed structures and property lines.
5. Performance Standards
All uses permitted in the underlying district will be a conditional use in the Steep Slopes Protection Area and must meet the following conditions for approval:
A. During Construction
The Sediment and Erosion Control plan must meet the Best Management Practices for Storm water Management and Erosion and Sediment Control as cited in the New Hampshire Department of Environmental Services "Storm water Management and Erosion and Sediment Control Handbook for Urban and Developing Areas in New Hampshire" and subsequent revisions.
B. Post Development Runoff
For a proposed contiguous site disturbance area equal to or less than 50,000 square feet, the Sediment and Erosion Control Plan must demonstrate that the post-development volume and peak flow rate, based on the 2-, 10- and 25-year, 24 hour storm event, shall not exceed the pre-development volume and peak flow rate for all flows off the property. The plan design should incorporate infiltration wherever possible.
For a proposed contiguous site disturbance area greater than 50,000 square feet, the Sediment and Erosion Control Plan must meet or exceed all minimum New Hampshire Department of Environmental Services requirements for "Alteration of Terrain" and subsequent revisions.
C. Excavations
Any grading cut and fill shall not exceed a 2:1 ratio. All excavations require a maximum grade of 15% with a minimum of 6 inches of topsoil covering the excavation area.
D. Vegetative and Topographical Features
Existing natural and topographic features, including the vegetative cover, should be preserved to the greatest extent possible. In the event that extensive amounts of vegetation are removed, the site shall be replanted with indigenous vegetation and shall replicate the original vegetation as much as possible.
E. Driveway
No section of any driveway may exceed a 12 percent slope for residential development or 8 percent slope for nonresidential site plans
F. Unsuitable Land
No structure shall be allowed on a slope greater than 25 percent prior to site disturbance
6. Design Guidelines
All proposed structures shall meet the following design guidelines:
A. Minimum Lot Size
The minimum allowable lot size for any lot shall be determined according to Article III.D.6, Lot Area. However, for property with steep slopes, that area with a slope greater than 25% is considered to be unsuitable for development and therefore is excluded from the calculation of lot size.
B. Lot Coverage
For district GR, allowable lot coverage is limited to 35 percent of Useable Lot Area . For district RR, allowable lot coverage is limited to 15 percent of useable lot area. For district CD, allowable lot coverage is limited to 50 percent of useable lot area.
C. Building Envelope
The building envelope (i.e. opening for building construction) permitted is a rectangle with an up-slope boundary 40 feet or less from the building, side boundaries 40 feet or less from each side of the building, and a down-slope boundary 25 feet or less from the building. Accessory structures shall be built within the building envelope. Building envelope boundaries shall be at least 35 feet from property lines.
D. Clearing for a View
In order to develop a view, trees may be removed beyond the building envelope for a width not to exceed 25 feet and extending outward there from at an angle of 45 degrees or less on both sides. The single 25-foot opening may be at any point along the down-slope boundary of the building envelope. The opening may extend outward to a distance where the tops of the trees are at or above the level of the down slope building foundation. No natural vegetative ground cover or stumps shall be removed except as necessary for a foot path to down-slope property, and for cutting that vegetation that has grown over 3 feet in height for the purpose of providing or maintaining a view. See appendix C
7. ADMINISTRATION OF BUILDING OR STRUCTURAL PERMITS
In addition to meeting the conditions set forth in this section, Building or Structural Permits shall be granted in accordance with the following pertinent procedures:
A. A Building or Structural Permit shall be granted by the Board of Selectmen or its agent upon a finding that the proposed use is consistent with the intent of the ordinance. The Board of Selectman or its agent shall provide notice of the application to the Conservation Commission and may require review by any board, commission, or other professional expertise deemed necessary.
B. The applicant must demonstrate that no alternatives are available for the productive use of areas outside of the Steep Slopes Protection Area, that no practicable alternatives exist to the proposal under consideration, and that all measures have been taken to minimize the impact that construction activities will have upon the area.
C. Upon fulfillment of the requirements of the Building or Structural Permit, and after a final site inspection, the Board of Selectmen or its agent shall issue a Certificate of Compliance. Usage of the site, other than for construction, is not approved until after site inspection and a Certificate of Compliance is issued.
8. Costs
All costs incurred by the town pertaining to the consideration of an application, including consultant's fees, on-site inspections, environmental impact studies, notification of interested persons, and other costs shall be borne by the applicant and paid prior to the Town's final action.
9. Additional Recommendations (Recommended but not required)
A. Only low level, indirect lighting should be used. Spotlights and floodlights should be avoided.
B. No portion of any structure should extend above the elevation of the ridgeline.
C. Structures should use natural landforms and existing vegetation to screen them from view from public roads and waterways to the extent practicable.
D. Cuts and fills should be minimized, and where practical, driveways should be screened from public view.
E. Building sites and roadways should be located to preserve trees and natural ground cover.
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