The following minimum standards shall apply to earth moving and land disturbing activity which is not otherwise exempt:
(1) Minimum alterations. Earth moving shall be limited to the minimum required for building foundations, driveways, drainage control structures and other approved improvements and immediate areas surrounding the building, structure, road driveway, drainage structure or other approved improvements. With the exception of approved stockpiling or restoration efforts, substantial earth moving beyond that required for the installation or construction of approved buildings, structures, driveways, roads, or drainage structures shall not be permitted.
(2) Cut and fill. Unless otherwise specifically approved by the town, cut slopes shall be no steeper than 1½ half horizontal to one vertical (1½:1) and fill slopes shall not be steeper than two horizontal to one vertical (2:1). Slopes exceeding 35 feet in height shall be benched at 35-foot intervals.
(3) Compaction of fill. All fill shall be stabilized in conformance with generally accepted engineering standards, including a compacted density of a least 95 percent. Vegetation which has been cut or cleared shall be removed from the site and shall not be covered by, or imbedded in, fill material.
(4) Timing of disturbance and prompt completion. The applicant for any land disturbing activity regulated hereunder shall propose a construction program to regulate the timing of construction which shall be designed to accomplish all earth moving and land disturbance in the shortest practical period of time. Absent extenuating circumstances beyond the control of the developer, failure to comply with the construction program shall constitute a violation of this article.
(5) Natural drainage channels. Natural drainageways shall be preserved to the maximum extent possible.
(6) Impact on adjacent property. Realignment of streams and natural drainage channels shall not be permitted except for the purpose of effecting a stream crossing and only as specifically approved by the community development 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 such alteration may adversely affect the property of another by either contributing to pooling or collection of waters, or to the concentration or intensification of surface water discharge.
(7) Density limits. Unless developed as a planned unit development pursuant to the provisions of subsection (8) of this section, development on lands that are subject to this article shall meet the density and development requirements shown in Table 1. No lot that is subject to the requirements of this article shall be approved for subdivision unless it complies with the requirements of this table.
TABLE 1
Average Natural Slope of Lot to be Subdivided | Minimum Lot Size (acres) | Maximum Building and Grading Envelope (BGE) |
30%—34% | 1 | 25% |
35%—39% | 2 | 20% |
40% or more | 5 | 15% |
Note: Minimum lot size may also be expressed in terms of dwelling units per acre. Thus, a two-acre minimum lot size would result in a maximum density of one dwelling per two acres (or one-half dwelling per acre) and so forth. This table shall not be construed to impair the clustering of dwellings and lots so long as maximum density is not exceeded.
(8) Planned unit development alternative. In lieu of developing land subject to the density limits contained in subsection (7) of this section, the owner of such land may propose to develop it as a planned unit development in accordance with the procedures contained in article IV of this chapter. The board of adjustment shall approve such application so long as the applicant demonstrates that the proposed planned unit development complies with applicable standards and requirements contained in article IV of this chapter, as well as the following additional standards:
a. The average natural slope of the building and grading envelope for each lot proposed for development shall be less than 30 percent.
b. With the exception of subsection (7) of this section concerning density limits, the proposed development shall comply with the requirements of this article.
(9) Storm drainage. The potential for rapid erosion is extremely high in mountainous and hillside areas. Steep slopes create perfect conditions for rapid movement of soils downhill during rainfall. Therefore, it is essential to address stormwater drainage and soil and erosion before land disturbing activities begin. Natural drainage flows shall be maintained wherever possible and developers and landowners are encouraged to use the best technology available to reduce the effects of this increased flow. All applications that affect the natural flow of stormwater must meet all local regulations, including, without limitation, the soil erosion and sedimentation control regulations. Stormwater flow shall not be altered from its natural flow so as to impact or damage the property of others.
(10) Clearing and grading.
a. A great deal of environmental damage associated with new development can be avoided if construction and the position of the development site are well planned. As the most potentially destructive part of the construction process, grading must be carefully planned and executed to maintain the stability of protected mountain and hillside property. The choice of an appropriate building site is the key to minimizing potential erosion problems. Grading, if required on the site, shall not take place prior to development plan approval and issuance of any permit required by the soil erosion and sedimentation control regulations. Only areas which have been approved for disturbance may be disturbed, and then only after all erosion measures and other regulations have been met.
b. The applicant's plans for meeting the following standards will be reviewed during planning or before construction begins:
1. Cut and fill activities shall be minimized by carefully selecting the site for structures, drainfields, septic tanks, etc.
2. Grading areas shall be clearly marked before any grading begins. Highly visible fencing is recommended to prohibit earth moving equipment from moving beyond designated grading boundaries.
3. Grading shall be phased so that prompt revegetation will provide optimal erosion controls.
4. All top and bottom edges of slopes caused by either cut or fill should be a minimum of two feet away from property lines.
(11) Retaining walls. Retaining walls, where required, shall be built to follow the contours of the land. Retaining walls, any portion of which exceeds ten feet in height, shall be designed to blend in with the natural landscape and shall incorporate vegetation to screen them from view.
(12) Requirements for streets and driveways. No new public or private street, road or driveway serving lands to which this article is applicable shall be permitted or constructed unless such street, road or driveway complies with the requirements of section 28-105.
a. All new public and private streets and roads and all driveways shall be designed and constructed to minimize the potential for landslides, erosion, and runoff.
b. Streets, roads and driveways shall be located such that the maximum number of existing trees on the site is preserved.
c. Streets, roads and driveways shall be designed to create the minimum feasible amounts of land coverage and the minimum feasible disturbance of the soil. Variations in roadway design and construction specified by these regulations shall be permitted, as may be approved by the community development director, to prevent the dedication of unnecessarily large amounts of land to such streets, roads or driveways. One-way streets shall be permitted and encouraged where appropriate for the terrain and where public safety would not be jeopardized. For example, a two-way street may have the directions of flow split into one-way pairs that differ in elevation, circumnavigate difficult terrain, or avoid tree clearance. Such streets shall have a minimum pavement width of 16 feet for one-way loop roads and divided streets less than 2,500 feet in length, and 18 feet for one-way loop roads and divided streets 2,500 feet or greater in length, and shall meet all other applicable standards for roads constructed within the town.
d. Except as may be modified herein, the maximum grade for any street or road is 15 percent. Grades within 100 feet of an intersection shall not exceed five percent without approval by the director. Where doing so will result in less disturbance to steep slopes, grades of up to 18 percent may be approved for distances not to exceed 500 feet per section or 15 percent of the length of the entire road system in the project, whichever is more. No grades in excess of 15 percent shall be approved in areas not served by functioning fire hydrants. Those portions of streets or roads for which the grade exceeds 15 percent shall be paved.
e. Except as may be modified herein the maximum grade for any new driveway is 22 percent. Grades of up to 25 percent may be authorized for distances not to exceed 300 feet where doing so will result in less disturbance to steep slopes. Where grades greater than 15 percent are authorized, driveways shall be paved. Where grades in excess of 22 percent are authorized, driveways shall have a minimum pavement width of 12 feet.
(Code 1989, § 92.206; Ord. of 11-18-2008; Ord. of 3-10-2009)