(A) Application. The following standards are generally accepted design standards and in some cases are standards mandated by the state. These standards are applicable to the typical situation. However, there are situations where these standards may not be appropriate due to unique topography, environmental factors, or a non-typical development proposal. In response to these situations, other standards may be appropriate. These standards are to be deviated from only upon the approval of the County Engineer, and watershed district or Water Management Organization (WMO) as deemed appropriate.
(B) Right-of-way and road width. Right-of-way and road width shall conform to the standards in the county and township comprehensive plans, all applicable ordinances and these standards. Roadways shall be considered in their relation to existing and planned roads, to reasonable circulation of traffic, to topographical conditions, to run-off of storm water, to public convenience and safety and in their appropriate relation to the proposed uses of the area to be served.
(1) Right-of-way. Right-of-way width shall conform to the widths in the table found in the appendix to this chapter. If there are conflicts, the widths as in the comprehensive plan shall govern. Cul-de-sac configurations are to have a minimum 70-foot radius for rural parcels and a minimum 60-foot radius for urban parcels.
(2) Road width. Road width shall conform to the standards in the table in the appendix to this chapter. If there are conflicts, the widths as in the comprehensive plan shall govern.
(3) Road grades.
(a) All center line gradients must be in accordance with the grade percent in the table in the appendix to this chapter. Wherever feasible, road grades within 50 feet at the curb line or shoulder line of an intersection shall be between .05% and 3.0%, and the cross-road grade shall be between 0.5% and 3.0%.
(b) Road grades may exceed the maximums presented above only upon demonstration that the grade standards cannot reasonably be complied with, the proposed grade will not cause a traffic hazard, impede the normal flow of traffic, and upon approval of the County Engineer.
(4) Road alignment. Horizontal and vertical alignment for principal, intermediate, minor arterials and collectors are to conform to the guidelines in the Minnesota Department of Transportation Road Design Manual and the State Aid Manual where applicable. All other roads are to be as follows:
(a) Horizontal alignment. Center line deflections are to be connected by a radius of not less than 100 feet.
(b) Sag vertical curves. Minimum length shall be 25 times the algebraic difference in percent of the intersecting grades.
(c) Crest vertical curves. Minimum length shall be 17 times the algebraic difference in percent of the intersecting grades.
(d) Road jogs. Road jogs shall have a center line offset of 150 feet or more when applied to local roads and 300 feet or more when applied to collector roads. Road jogs are to be avoided for arterial roads.
(e) Minimum tangent length. Minimum tangent length between curves are to be 75 feet.
(5) Road design loads. Roads classified as principal, intermediate or minor arterial are to be designed to a minimum nine-ton loading. All local residential roads are to be designed to a minimum five-ton loading. A seven-ton loading is recommended on local roads and is required on all collector roads. Roads serving or connecting to commercial and industrial areas are to be designed to a minimum nine-ton load. The designs are to be in accordance with the current MNDOT flexible pavement design standards. All calculations along with a soils report are to be submitted with the plans for review and approval by the County Engineer.
(6) Road intersections.
(a) The angles formed by the intersecting roads are to be at 90 degrees. A maximum 15-degree deviation may be permitted when circumstances will not allow a 90-degree angle. All other situations are to be avoided.
(b) Intersections of more than four corners are prohibited.
(c) Road intersection radii are to be a minimum 30 feet. Road and alley intersections are to be rounded by a radius of not less than 6 feet. The intersection of the straight section with the turn- around of a cul-de-sac road are to be rounded by a radius of not less than 30 feet. Center islands are to be prohibited in all cul-de-sac turnarounds.
(7) Private roads. Private roads may be permitted for access to PUDs, townhouses or other such development where an association or other suitable mechanism is provided to ensure maintenance and upkeep. The requirements for private roads shall be the same as the requirement for public roads.
(C) Drainage facilities and erosion control.
(1) General requirements. The following shall apply, in addition to the stormwater pollution prevention plan (SWPPP), watershed district or Water Management Organization (WMO), or similar agency, if one exists for review and, if required, approval. Detailed plans and calculations are to be submitted along with the road plans for all drainage works. The plans are to address the drainage for the entire area to be subdivided and demonstrate how the drainage related to the drainage of the surrounding lands. The drawings are to show location, capacity, type and size of any culverts and storm sewers or other drainage facilities. Storm water and sedimentation retention basins may be required.
(2) Surface water runoff systems. Surface water runoff systems are to be as follows:
(a) Consider future expansion to undeveloped areas.
(b) Base design on current adopted comprehensive plan.
(c) Minimum culvert size of 18 inches on rural sections.
(3) Storm water retention and sedimentation ponds. Storm water retention and sedimentation ponds are to be as follows: the pond or ponds are to be constructed with initial phases of site grading or road construction and are to be excavated one foot below finished bottom elevation for sediment storage during construction.
(4) Erosion control barriers. Erosion control barriers are to be as follows: the developer shall be responsible for maintaining barriers in a functional condition until such time as the barriers are deemed no longer necessary by the governing body.
(5) Drainage easement.
(a) Easements are to be a minimum of 20 feet in width centered above the pipe on the storm sewer system outside of right-of-way areas.
(b) Easements for above ground drainage are to be a minimum of ten feet on either side of the projected high water level.
(c) Easements around storage ponds are to include the 100-year high water level.
(d) All these easements are to be dedicated to the public unless otherwise requested by the county.
(6) Buildings adjacent to storage ponds. Buildings shall not be constructed within 50 feet of the 100-year high water level.
(D) Facilities - other than sewer, water, drainage.
(1) Location. All utility facilities, excepting those addressed in divisions (B) and (C), and including but not limited to gas, electric, telephone, and cable television are to be located underground throughout the subdivision. General location and the location of junction boxes, transformers, and similar structures are to be located as specified by the County Engineer.
(2) Easements. Easements centered on all lot lines are to be provided for utilities/facilities and said easements are to be at least 10 feet wide on either side of the lot line. Where topographical or other conditions or the design of the subdivision makes impractical the inclusion of the utilities within the rear lot line easements, perpetual, unobstructed easements at least 20 feet in width centered on the lot line are to be provided along the side lot lines with satisfactory access either to the road or rear lot line.
(Am. Ord. 70-2010, passed 1-25-11)