The county finds that the health, safety, and general public welfare of the residents of the county will be promoted by establishing standards for the development and grading (cuts or fills) on slope areas wherever development is proposed to be located in the county. The purpose is to minimize soil and slope instability and erosion, to minimize the adverse effects of grading, to minimize subsurface water problems, preserve the character of the county's developed hillsides, and to otherwise supplement and amplify the county subdivision and zoning ordinances. The provisions herein are designed to accomplish the following:

   A.   Prohibit development of uses which would likely result in a hazardous situation due to slope instability, rockfalls, excessive soil erosion, or expansive soils or subsurface water problems.

   B.   Provide for safe vehicular circulation and access.

   C.   Encourage preservation of open space by encouraging cluster housing, density transfer, density bonus, or other design techniques, and to preserve the natural terrain by protecting against slope failure from any of the above identified conditions.

   D.   Protect against the above identified conditions in instances where clustering or other design techniques may be used to preserve the natural terrain. (Ord. 2006-910-O, 5-2-2006)

CUESTA: A land form that has a steep ascent in one direction and a gentle descent in the opposite direction as designated on the ridgeline map. The steep slope is the cuesta face, an erosion escarpment, and the gentle one is the back slope of the cuesta. The crest of the cuesta forms a ridgeline.

CUT: Land surface which is reshaped by man through the removal of soil, rock, or other materials.

DEVELOPMENT: The carrying out of any subdivision or building activity, or clearing of land as an adjunct of construction. A development shall be considered to be a subdivision, platting, including single-family residential, townhomes, planned development, multi-family, commercial, and/or industrial development.

DEVELOPMENT PARCEL: Any quantity of land capable of being described with such definiteness that its location and boundaries may be established, which is designated by its owner or development as land to be used or developed as a unit or which has been used or developed as a unit.

EXCAVATION: Any disturbance to the ground, including, but not limited to, clearing, grubbing, rock removal, cutting, tunneling, drilling, or any other activity which alters the natural ground. "Minor excavation" shall mean a vertical cut of four feet (4') or less, or a disturbance of less than ten thousand (10,000) square feet of surface area.

FILL: The deposit of soil, rock, or other materials as placed by "man".

GEOTECHNICAL ENGINEER: A person with a Master's Degree in Civil Engineering with emphasis on geotechnical engineering from an accredited university who, through training and experience, is able to assure that geological factors affecting engineering works are recognized, adequately interpreted, and presented for use in engineering practice, and for the protection of the public. Such engineer shall be licensed in the state of Utah.

GRADING: Includes any work resulting in cuts or fills of an area of land proposed for development purposes.

LEDGE: The first substantial abrupt change in slope along with the top edge of a plateau or ridgeline.

PLATEAU: A flat or predominantly flat area of land which is raised sharply above adjacent land on at least one side.

RIDGELINE: The junction of a rising steep slope on one side and a descending slope that may either be gentle or steep on the other side.

SETBACK: An area in which no structure or building is allowed.

SLOPE: A vertical rise in feet measured over a horizontal distance, expressed as a percentage.

TABLELAND: Land where the slope in any direction is less than fifteen percent (15%).

UNDISTURBED LAND: An area that remains in a natural, pristine condition and is not subject to grading, excavation, or other similar disturbance. (Ord. 2006-910-O, 5-2-2006)

In furtherance of the purposes set forth above, site disturbance related to hillside development shall comply with the following schedule:

   A.   Zero to nineteen percent (0-19%) slope: See existing ordinances and standards unless otherwise required by the county.

   B.   Twenty to twenty nine percent (20-29%) slope: Seventy percent (70%) of the slope shall remain undisturbed. The seventy percent (70%) area is based upon the overall area/development rather than per lot.

   C.   Thirty percent (30%) and greater slope: Ninety percent (90%) of this slope category shall remain undisturbed. The ninety percent (90%) area is based upon the overall area/development rather than per lot.

   D.   The county commission shall have the authority to adjust the above percentages, for cause, after receiving a recommendation from the county staff and the land use authority. (Ord. 2006-910-O, 5-2-2006)

   A.   Slope: Slope shall be determined on an individual development parcel basis as an average percent natural slope for purposes of density limitations.

   B.   Procedure: The location of the natural twenty percent (20%) to twenty nine percent (29%) and thirty percent (30%) or greater slopes shall be determined based upon the following procedure:

      1.   Preparation Of Contour Maps: Current contour maps shall be prepared and certified by a licensed professional engineer or surveyor showing contours at intervals no greater than five feet (5') drawn at a scale of not less than one inch equals one hundred feet (1" = 100') scale.

      2.   Verification: Field surveys may be required of the applicant by the county public works director to verify the accuracy of the contour lines shown on the contour map. All development on slopes in excess of twenty percent (20%) shall identify profile lines which shall be used for performing the field survey. Profile lines shall be perpendicular to contour lines and in no case occur at intervals greater than one hundred fifty feet (150') apart or seventy five feet (75') from a property line. (Ord. 2006-910-O, 5-2-2006)

All development on slopes in excess of twenty percent (20%) shall require a grading development permit reviewed and recommended by the land use authority and granted by the county commission prior to any grading or construction activity. The county staff shall first review all proposed developments for compliance with this and other county ordinances and standards, including the Utah uniform building standards act rules, and the international building code, and make a recommendation to the land use authority and to the county commission for approval, conditional approval, or denial of the proposed development. Developments shall be reviewed for suitable construction solutions for addressing geologic hazards, expansive soils, landslides, rockfalls, potential slope instability, and subsurface water, or other public health or safety problems or issues.

The fee for the development permit shall be as may be established by the county commission from time to time. (Ord. 2006-910-O, 5-2-2006)

Any application for a grading permit on slopes greater than twenty percent (20%) within the county shall be required to be submitted to the county staff with the following technical information and reports:

   A.   An earth grading plan, prepared by a licensed civil or geotechnical engineer. Said plan shall show (unless excepted by the county staff):

      1.   Existing and proposed contours and cross sections.

      2.   Accurate contours showing the topography of the existing ground, and which must be extended at least two hundred feet (200') outside of all boundary lines of the site, or sufficient to show on and off site drainage.

      3.   The slope of proposed cuts and fills shall be shown on the grading plan.

      4.   Landscape or other approved techniques for stabilizing cuts and fills.

      5.   All cuts and fills shall conform to the Utah uniform building standards act rules, and the international building code.

   B.   A drainage plan showing plans of all surface and subsurface drainage systems and facilities, walls, cribbing or other erosion protection devices to be constructed in connection with, or as a part of, the proposed project, together with a map showing the drainage area and estimated runoff of the area served by any drainage system or facility. The drainage plan will show plans for protecting expansive areas that may be a part of the overall development.

   C.   A plan showing all existing or proposed streets, buildings, easements, or drainage channels on or proposed to be located on the property.

   D.   Elevation drawings showing the location of all existing and proposed structures and how or to what extent hillside cuts or fills will be covered and/or retained by the proposed development.

   E.   An earth grading plan prepared by a licensed professional engineer which plan shall show the following:

      1.   Topography: Property contours shall be shown at two foot (2') intervals and five foot (5') intervals for slopes.

      2.   Terrain Details: Special notes and details of the existing terrain shall be noted on the required topographic information.

      3.   Proposed Earth Grading Plan Details: The dimensions, elevations and contours of any proposed earth grading shall be shown.

      4.   Material Disposal: A description shall be included of the methods to be employed in disposing of soil and other material removed, including the location of the disposal site.

      5.   Timetable: A schedule shall be included showing when each stage of the project will be completed, including the estimated starting and completion dates.

   F.   Drainage control plan and report.

      1.   All drainage systems shall be separate and independent from the sanitary sewer system.

      2.   Drainage and flood control shall be designed in conformance with the county flood control master plan where applicable.

      3.   When modification to a natural drainage channel is proposed within the development, such changes will be addressed in the drainage study and shown on the improvement plans. The developer may be required to dedicate rights of way or to record drainage easements for structures and/or improvements needed to carry storm water runoff in the event approval is given for the proposed modifications. The developer shall be required to check with other agencies besides the county to determine whether or not such agency claims some jurisdiction over the land in question.

      4.   The point of location where the natural drainage channel enters and leaves the property may not be changed without approval of the county.

      5.   Any drainage basins located upstream of the development shall be considered to be fully developed in conformance with the county's current land use plan. Effects on the downstream property owners relative to increased flood potential and nuisance water shall also be considered in the design, including acquisition of easements or agreements where necessary, or construction or modification of improvements where needed.

      6.   The developer shall provide the necessary means to assure drainage within the property being developed by making use of existing facilities or natural washes and constructing other planned improvements.

      7.   In general, it shall be required that each new development handle its storm water runoff in such a manner that no net increase in storm runoff above the natural state will occur on the downstream properties. In other words, the preproject flows must not be exceeded by the postproject flows.

      8.   Streets are significant and important in urban drainage, and full use shall be made of streets for storm runoff up to reasonable limits, recognizing that the primary purpose of streets is for traffic. Reasonable limits of the use of streets for transportation of storm runoff shall be governed by the below listed design criteria:

         a.   Local street: No curb overtopping. Flow spread must leave at least one lane free of water.

         b.   Collector street: No curb overtopping. Flow spread must leave one lane free of water in each direction (2 lanes minimum).

      9.   When the above encroachment is exceeded, an independent storm water system shall be designed and constructed based upon a 10-year storm. The minimum storm drain size shall be twelve inches (12").

      10.   The storm water from a 100-year frequency storm shall be adequately conveyed either within the limits of the street rights of way or in storm drain easements without creating flood hazards to dwellings.

      11.   When an underground piping system is required, it shall be designed to carry a 10-year storm. Major hydraulic structures shall be designed to carry a 100-year storm.

      12.   Retention and detention basins on hillsides shall not be allowed.

      13.   Cross gutter drains on streets shall be avoided wherever possible. They shall not be allowed on collector and higher order streets.

      14.   When springs or other ground water sources are found on or above the developer's property, the construction of an engineered underground pipe system to eliminate the nuisance of this water will be required. Minimum pipe size shall be eight inches (8"). Plans shall be approved by the county public works director.

      15.   Necessary measures shall be taken to prevent erosion and scour at all points throughout the development. It shall be mitigated at all points of discharge and at the face of any cut or fill slope throughout the development.

      16.   During grading or construction on any property, including off site construction, the developer shall control both water used for construction and storm runoff in such a manner as to not adversely affect any adjoining properties, nor add silt or debris to any existing storm drain, wash, channel or roadway.

   G.   The drainage plans and construction drawings shall be approved by the county public works director prior to final plat approval or site approval and prior to the issuance of any building permits. The report shall be prepared in conformance with general accepted engineering practices.

   H.   A geology and soils report shall be prepared by a licensed professional engineer trained and experienced in the practice of geotechnical engineering in the area proposed for development, and shall be reviewed by the county public works and the land use authority. The report shall contain at least the following information:

      1.   A slope stability analysis shall be prepared containing conclusions and recommendations concerning the effects of a grading operation, introduction of water, both on and off site, including, where applicable, on mesa tops, seismic activity, and erosion on slope stability.

      2.   A foundation investigation with conclusions and recommendations concerning the effects of soil conditions on foundation and structural stability, including, where applicable, sheer strength, and shrink/swell potential of soils.

      3.   The location and yield of springs and seeps which shall be shown on the site plan.

      4.   Structural features including any geological limitations.

      5.   Existence of surface hazards including potential for failure of slopes or rock overhangs above the subject property.

      6.   Conclusions and recommendations regarding the effect of geologic conditions on the proposed development, together with recommendations identifying the means proposed to minimize any hazards to life or property, or adverse impact on the natural environment.

   I.   Prior to final plat or site plan approval of a project, a landscape plan, prepared by a licensed landscape contractor or a landscape architect, in conjunction with the overall site plan, must be submitted for approval. The plan shall outline areas being excavated and filled and describe in detail how the developer will restore or replant these areas. The plan shall specify types of temporary or permanent retention being used, together with sprinkler plans and water usage methods suitable to the soils of the project.

   J.   Other reports, plans, and information as may be deemed necessary by the county staff or public works director may be requested as a condition of the application. All studies and plans shall require review by the public works director. (Ord. 2006-910-O, 5-2-2006)

A cash bond or irrevocable letter of credit to assure hillside restoration shall be provided prior to issuance of a hillside development permit for projects disturbing more than one acre, or where the public works director recommends and the land use authority approves that a bond or letter of credit is needed on a site of less than one acre. Such financial guarantee shall be provided in an amount sufficient to ensure necessary soil stabilization, including grading, planting, and maintenance. In the event that the developer fails to complete the hillside restoration in accordance with the approved plan within one year from the issuance of the permit, and upon recommendation of the staff and approved by the land use authority, additional time may be granted by the county commission in the event that significant progress toward completion of the project is underway. The bond or letter of credit shall cover the cost, as estimated by an approved landscape architect, qualified contractor, or civil or geotechnical engineer, and approved by the public works director, to restore the hillside to an acceptable level of appearance and stability. If the work is not completed as agreed upon at the time of the issuance of the permit, the county may call the bond or letter of credit and the county shall be responsible to complete the work. (Ord. 2006-910-O, 5-2-2006)

The following standards apply to all public streets. (See subsection 11-5-3C5 of this code for street width requirements.)

   A.   All street grades shall be a maximum of fifteen percent (15%). However, when conditions can be made more desirable by exceeding fifteen percent (15%) and produce less disturbance to the existing terrain, along with improvement in safety features, upon recommendation of the public works director and approved by the land use authority, grades may exceed the fifteen percent (15%) limit based on the merits of each case.

   B.   Where at all possible, all intersections shall be ninety degree (90°) angles. In the event an acute angle intersection is required, it can be mitigated by realigning to achieve a ninety degree (90°) intersection using a fifty foot (50') section prior to the PC of the curve or a landing area design in which a vehicle is brought ninety degrees (90°) to the intersecting road.

   C.   Intersections should be spaced far enough apart so that the traffic stopped to make left turns at one intersection does not interfere with traffic movements at the adjacent intersections. On low volume streets such as access from one local street to another, the minimum distance should be two hundred feet (200'). For local to collector streets the minimum distance should be two hundred fifty feet (250').

   D.   The design of geometric features such as horizontal and vertical alignment will depend on the design speed selected for each street. The design speed is primarily determined by the street function and classification, and is the maximum speed for safe and comfortable operation of a vehicle. Other than a collector, all streets in hillside areas are classified as local streets with a speed of thirty five (35) miles per hour or less. The use of design speeds other than those listed must be approved by the public works director, who may decide that the speed provided in this section be reduced to that which is reasonable and prudent under the conditions and having regard to the actual and potential hazards.

 

 

Note:

1.   The variance of design speeds may be granted by the public works director to no greater than 5 miles per hour or less when conditions warrant. Variances will not be granted for short segments of roads, but for entire contiguous stretches so that consistency and driver expectancy are maintained.

   E.   At intersections, adequate, clear sight distance should be provided to permit drivers entering the street to see approaching traffic from a long enough distance to allow them to decide when to enter the street safely, turn onto the street, and accelerate in advance of approaching traffic. Clear sight distance should be in accordance with the following table:

 

 

   F.   The vertical alignment of residential streets should ensure that drivers can safely negotiate hills in adverse weather and that sight distances are adequate for safety. The requirements for vertical curve design shall be in accordance with the latest editions of AASHTO geometric design of highways and streets. All designs shall be approved by the county public works director.

Vertical alignment with the intersection is also of special nature, and design alternatives may be required. As a guideline, the approach area where vehicles stop while waiting to enter an intersection shall not exceed four (4) to five percent (5%) from the gutter line of the street being intersected for a distance of fifty feet (50') though a range of fifty feet (50') to one hundred feet (100') is more desirable. This applies to all intersections, except those intersections where both intersecting streets are collectors. The landing area for a collector street shall be designed for a grade of two percent (2%) to three percent (3%) for a distance of one hundred feet (100').

   G.   The minimum sight distance to be provided before a stop is required shall comply with the requirements set forth in the table below:

 

 

   H.   The minimum centerline radius for horizontal curves on local streets is outlined as follows:

 

 

   I.   The minimum requirements for street cross section configurations are based on the following factors:

      1.   Traffic capacity,

      2.   Design speed,

      3.   Projected traffic,

      4.   Designs to reduce scarring.

Alternate street cross sections may be used if applicable safety and traffic standards are met and approved by the public works director. (See Washington County construction standards to identify alternates that may be available.) (Ord. 2006-910-O, 5-2-2006)

   A.   For safety purposes, all ridgelines, plateaus, and cuestas shall be a minimum of fifty feet (50') away from any building construction or further development unless a greater setback is required as recommended in the geotechnical report.

   B.   Retaining walls should be colored to match surrounding natural landscaping.

   C.   The exterior color of buildings on hillside slopes above twenty percent (20%) should be earthtone to blend with the surrounding natural landscape.

   D.   "No disturbance" areas shall not be included within lots unless approved by the land use authority and county commission, but should be part of the common area of a project. Common areas shall be owned and maintained by the project's homeowners' association, or may be deeded to the county upon county commission approval.

      1.   No disturbance areas shall be identified on the ground with temporary fencing or other approved means to prevent accidental disturbance of the area during construction. Such fencing shall be installed prior to issuance of a grading permit.

      2.   No disturbance areas shall be identified on final plats or site plans, whichever is applicable. (Ord. 2006-910-O, 5-2-2006)

In the event that the county staff makes requirements which are not acceptable to the developer, the developer may request a hearing of the matter by the county commission. Said request shall be made in writing and submitted within ten (10) calendar days thereafter. The county commission shall hear and make final determination of the issue. (Ord. 2006-910-O, 5-2-2006)

In addition to those penalties prescribed in subsections 10-1-21A and B of this title, the public works director or building official shall have the right to order a halt to construction of any improvements within a hillside development where, at their discretion, there exists a condition which violates, or threatens to violate, any provisions of this chapter. Such suspension of construction activities shall continue until the public works director, or building official, is satisfied that measures have been implemented for substantial compliance with this chapter. (Ord. 2006-910-O, 5-2-2006)

Notwithstanding the requirements of this chapter, the requirements herein are intended to apply to any and all development projects proposing to develop land for residential, commercial, or industrial subdivisions, and/or planned development purposes. Grading for strictly mining or mineral development, unless otherwise required by the public works director, is exempt from this chapter. (Ord. 2006-910-O, 5-2-2006)