The purpose of the Steep Slope Conservation District is to establish basic performance standards for development within steep slope areas to mitigate sedimentation and erosion.
Slopes shall be categorized as steep (12% to less than 25%), very steep (25% to less than or equal to 35%) and severely steep (35% and over).
The intent of this article is as follows:
To conserve and protect sloped land from inappropriate development, such as excessive grading and extensive vegetation removal.
To avoid potential hazards to property and the disruption of ecological balance which may be caused by increased surface water runoff, flooding, soil erosion and sedimentation, blasting and ripping of rock, and landslides.
To encourage the use of sloped land for conservation and other uses which are compatible with the preservation of natural resources and protection of the environment.
To avoid loss of biodiversity and wildlife habitat and corridors.
Interpretation of steep slope areas:
In any application where the lot includes areas of steep, very steep slopes and severely steep slopes, the applicant shall, using two-foot contours, delineate slopes from 12% to 25%; greater than 25% but less than 35%; and greater than or equal to 35%. The applicant shall use an actual field topographic survey as the source of contour information and the basis for depicting such slope categories.
This article shall apply only to those steep and very steep slopes which exist for three consecutive two-foot contour intervals (six cumulative vertical feet of slope). All steep, very steep, and severely steep slope areas shall be shown for the purpose of City review and verification, but only those occurring over three consecutive two-foot contour intervals will invoke the standards of § 595-151.
Once delineated, the mapping provided by the applicant shall be reviewed by the City Engineer. The applicant shall be required to follow all regulations of this article for those areas which reflect steep and very steep slope conditions as determined in accordance with this article through the City Engineer's review.
Before a permit is issued for any construction or land disturbance on land within or affecting steep and very steep slope areas, the following material shall be submitted for review by the City Engineer:
Plans drawn to a scale of at least one inch equals 50 feet, sealed by a registered professional engineer, depicting the following:
The location, dimensions and elevation of the property.
Existing and proposed uses and development.
An earthmoving plan of the property which indicates existing and proposed grades with contour lines at two-foot intervals within the area of any proposed activity, disturbance or construction. All areas of steep and very steep slope shall be graphically highlighted.
A site plan indicating existing and proposed buildings, structures, other impervious surfaces, storm drainage facilities and retaining walls. The site plan shall also depict within areas of steep and very steep slopes existing vegetation, including woodlands, open areas and their ground cover type, as well as proposed landscaping material to be installed.
Typical cross section and elevations of the property and proposed buildings and structures at intervals prescribed by the City Engineer, as well as architectural plans, building elevations, and site sections.
Photographs showing existing uses, vegetation and topography within the steep and very steep slope areas.
A statement, signed and sealed by a registered architect or professional engineer explaining the building methods to be used in overcoming foundation and other structural problems created by slope alteration; the proposed techniques to preserve natural drainage and prevent soil erosion and sedimentation; and the methods proposed to avoid excessive surface water runoff to neighboring properties and/or streets.
Plan, profile and typical cross sections of any proposed street, emergency access or driveway within areas of steep and very steep slopes, with the seal of a registered professional engineer thereon.
In evaluating any application, the City Planning Commission shall determine consistency of the proposal with the following:
In areas with a slope of 12% to 25%, no more than 30% of such areas shall be regraded, cleared, built upon or otherwise altered.
In areas with slope of 25% to 35%, no more than 15% of such areas shall be altered, regraded, cleared, built upon or otherwise altered.
Disturbances shall be minimized where the length or area of steep and very steep slope is extensive both on the site and on adjacent lands within 50 feet of the site.
In areas of slope of 35% or greater, no area shall be altered, regraded, cleared, built upon or otherwise altered.
The proposed development, any impervious cover and resultant disturbance to the land and existing vegetative cover will not cause stormwater runoff and/or related environmental problems off the site.
Removal of or disturbance to existing vegetation in steep slope areas shall be minimized. The proposed impacts on existing vegetation shall be evaluated in terms of the potentially detrimental effects on slope stability, conveyance and recharge of stormwater, aesthetic characteristics of the landscape and existing drainage patterns. Further, it shall be demonstrated that any and all reasonable mitigation techniques and procedures will be utilized or have been considered in the preparation of the plan, such as revegetation measures, control of soil erosion and sedimentation, stormwater management, and the like. For purposes of such demonstration, the City may request additional information, including, but not limited to, an erosion and sedimentation plan.
Important visual qualities of the site shall be retained to the maximum extent possible. In addition to vegetation, these may include hilltops/ridgelines, rock outcroppings, and the natural terrain and contours of the site.
Road and driveway construction shall follow the natural topography to the maximum extent possible. Cuts, fills and grading shall be minimized.
Innovative, imaginative building techniques that are well-suited to slope conditions shall be encouraged, consistent with other applicable codes and regulations.
The stability of the slope, as characterized by the existing interrelationships among the soil, vegetation, and rock, shall be disturbed as little as possible.
Proposed buildings and structures shall be of sound engineering design. Footings shall be designed in response to the site's slope, soil and bedrock characteristics. Footings shall extend to stable soil and/or bedrock.
All disturbed areas shall be stabilized and seeded or planted, and notes to this effect shall appear on all plans.
Finished slopes of all permitted cut and fill shall not exceed three to one or 33%, unless the applicant can demonstrate the method by which steeper slopes can be stabilized and maintained adequately.