17.25.010 Design standards.
Each new subdivision platted in the town of Granby, to some degree, affects the character and environmental appeal of the land, the cost of services and maintenance to the purchasers and the town government, and the interests of investors in the subdivided land and surrounding areas. New subdivisions shall provide safe, convenient travel routes to and from and within the subdivision. Each lot shall provide a desirable setting for construction so that natural features of the land may be preserved, views protected, privacy permitted and screening from traffic ways made possible. Area needs for flood channels, open space, parks, schools, fire stations, water and sewage treatment facilities and similar community facilities must be provided depending on the location and density of each development. These concepts hold true for new development on existing platted parcels, and therefore compliance with the design standards within this section shall also be required for any site plan required under GMC 16.125.180. Although GMC 17.15.010 and 16.20.050 provides for variances under certain circumstances, the following design standards shall be followed unless a variance from these provisions is requested.
(a) Special Site Considerations.
(1) Steep, unstable or swampy land, and land subject to inadequate drainage, geological hazards, avalanche or rock slides, shall be identified and unless acceptable provisions are made for eliminating or controlling problems which may endanger health, life or property, such sites shall not be platted for residential occupancy. Land not usable for residential purposes may be set aside for open land uses, such as for parks, conservation areas or various agricultural uses.
(2) Any land subject to flooding or located in a natural drainage channel or in a fire hazard area shall not be platted for occupancy until adequate provisions to eliminate or control hazards are made and approved by the commission. These provisions shall be made to protect the health, safety and welfare of the public, as well as to eliminate any flood or fire hazard resulting from the development of the area. Areas subject to flooding may be left as open space or reserved as easements.
(3) Where a residential subdivision borders a railroad or highway right-of-way, the commission may require a buffer strip of such an extent and type as may be practical, or other adequate protection against hazards and undesirable effects of the railroad or highway, such as a fence installed by the applicant prior to conveyance of the lots.
(b) Streets, Alleys, and Easements.
(1) Streets shall be aligned to join with planned or existing streets adjacent to the subdivision. The commission may require streets and roads to provide direct, continuous routes to all adjacent lands, whether such adjacent lands have been subdivided or not, where no other legal access exists. The location of streets providing access to adjacent lands shall be selected by the subdivision planner, provided such location shall be reasonably calculated to provide usable access to the adjacent lands. Temporary cul-de-sacs shall be provided at the end of any street giving access to adjacent lands until connecting streets on the adjacent lands have been constructed.
(2) Streets shall be designated to bear a logical relationship to the topography.
(3) Whenever streets are not aligned, offsets shall be at least 135 feet, centerline to centerline.
(4) Intersections shall be as nearly at right angles as possible, with no intersections designed at an angle of less than 75 degrees.
(5) Cul-de-sacs shall be permitted, provided they are not more than 500 feet in length, and have a turnaround diameter of at least 90 feet, unless the topography dictates the use of a longer cul-de-sac, in which case the approval of the commission shall be obtained. The drainage should be toward the intersecting street, or a drainage easement shall be required between the cul-de-sac and the rear lot line of the lowest lot.
(6) Dead-end streets, with the exception of cul-de-sacs, shall be prohibited.
(7) Restriction of access shall be required when a subdivision or portion thereof adjoins an arterial highway. Marginal access streets, reverse frontage with screen planting contained in a non-access reservation, deep lots or similar treatment shall be required to reduce the impact of the traffic on residential properties and to avoid interference with the movement of the traffic on arterial highways.
(8) Half Streets Shall Be Prohibited. When a proposed half street in one subdivision is adjacent to another property, the approval of the adjacent owner shall be obtained and the entire street shall be platted and dedicated by the owners. The responsibility for acquiring the additional right-of-way shall be with the applicant.
(9) Reverse curves on arterial highways shall be joined by a tangent at least 200 feet in length.
(10) Reverse strips, controlling access to streets, are permitted only when the control of such strips is given to the town under conditions approved by the commission.
(11) Street widths and grades shall be as follows:
|
Classification |
Right-of-Way Width |
Surface Width |
Minimum Grade |
Maximum Grade |
|---|---|---|---|---|
|
Arterial Highways |
150' |
70' |
.5% |
5% |
|
Major Roads |
100' |
50' |
.5% |
6% |
|
Collector Streets |
80' |
40' |
.5% |
7% |
|
Local Streets |
||||
|
More than 1 lot/acre |
60' |
30' |
.5% |
7% |
|
Less than 1 lot/acre |
60' |
20' |
.5% |
7% |
|
Marginal Access Streets |
60' |
20' |
.5% |
7% |
|
Alley Where Permitted |
20' |
20' |
|
|
|
Sidewalks |
||||
|
Business |
|
10' |
|
|
|
Residential |
|
4' |
|
|
|
Easements |
20' |
|
|
|
(12) Alleys and Easements.
(i) Alleys in residential subdivisions shall be prohibited unless they are necessary to continue an existing pattern.
(ii) Alleys shall be provided in commercial and industrial areas, except that this provision may be waived when no other provisions are made and approved for service access.
(iii) Easements of not less than 20 feet in width shall be provided along all rear lot lines and along certain side lot lines for utilities when alleys are not provided. Such easement may be provided by 10-foot easements on each of the adjoining lots. Utility easement at different locations may be provided upon recommendation by the affected utility companies and approval of the commission.
(13) Street Signs. Town street signs shall be installed at all intersections in the subdivision according to the street names and numbers approved by the town. The applicant will be required to install road signs of the size and type already in use in the town and in the locations required by the town. However, private streets, if approved, shall be signed with a different color (white letters on a red background) than those of public streets. The applicant will be required to install these signs at his expense.
(c) Blocks.
(1) Blocks should be more than 400 feet in length, but less than 1,000 feet.
(2) Block lengths and widths shall be suitable for the uses contemplated and the zoning or other land use requirements pertaining to minimum lot sizes and dimensions.
(d) Lots.
(1) Lot dimensions and sizes shall conform to applicable zoning and other land use requirements.
(2) Each lot shall have access to a dedicated street.
(3) Lots with double frontage shall be avoided, except where essential to provide separation from major arterials or incompatible land uses.
(4) Side lot lines shall be substantially at right angles or radial to street lines.
(e) Dedications and Public and Private Reservations.
(1) Dedication of right-of-way for streets giving access to adjacent lands and adjoining dedicated streets, and drainage and utility easements, shall be required.
(2) The commission shall require the dedication, reservation or conveyance of areas or sites suitable for public purposes such as parks, flood channels, scenic areas and green belts. The location of all such areas or sites shall be mutually agreed upon by the applicant and the commission. The commission may consider recommendations from other public agencies which would be directly involved in the development and service of these areas.
(3) Reference shall be made to the master plan in order to determine general locations for various public facilities.
(f) Design Standards for Drainage, Sewer and Water.
(1) Storm Drainage. Land within an existing 100-year floodplain or land which is subject to inundation shall not be platted for occupancy unless the flooding condition is alleviated according to plans approved by the commission and the board.
(2) Drainage Standards and Erosion Control Standards.
(i) Drainage Plan. Every development involving anything other than four or fewer single-family residential lots on less than one acre total, shall include a drainage plan which shall:
(A) Be produced and certified by a licensed engineer;
(B) Be subject to the approval of the town engineer;
(C) Be designed to restrict site drainage to a rate no greater than the historical rate before development for the 100-year storm, or include development of a storm drainage system to convey runoff water to an acceptable site;
(D) Identify existing channels, dry washes and stream beds with their 100-year storm calculations;
(E) Include calculations and quantities of flow at points of concentration;
(F) Identify possible breach points where irrigation ditches and dry washes intersect;
(G) Depict the above information for the entire drainage basin unless the town engineer determines other boundaries for the plan; and
(H) Include a vicinity map locating the development and its drainage basin.
(ii) Drainage Improvements. Drainage improvements shall be provided by the developer and designed to meet the criteria of this section. They shall also meet town engineering and construction specifications for streets, water and sewer.
(iii) Drainage Easements. Drainage easements shall be designed to meet the criteria of this section. The minimum width for a drainage easement shall be 10 feet. Fifteen feet shall be required where needed, as determined by the town engineer, for vehicular access to maintain the system. No permanent or temporary structure or other obstruction of any kind shall be located on or within the easement.
(iv) Erosion and Sediment Control, Stabilization, and Revegetation. At the discretion of the town engineer, a development plan shall include plans for erosion and sediment control and for slope stabilization and revegetation. The town engineer shall base any decision to require such plans on the size and slope of the subject property, the amount of soil and vegetation to be disturbed, the extent to which natural topography will be altered and the likelihood of adverse impacts on neighboring properties and on the community as a whole.
(3) Plan for Erosion and Sediment Control.
(i) The plan for erosion and sediment control shall be designed to ensure:
(A) That natural drainage patterns are preserved in a manner which will minimize disturbance of natural vegetation and soil cover;
(B) That natural drainage patterns are preserved and protected from increased water flows which may otherwise tend to alter such patterns or subject existing channels and adjacent areas to increased erosion;
(C) That appropriate consideration of soil types is made in the design of cuts and fills, building sites, septic tanks and other land uses; and
(D) That structures are provided as necessary to prevent or minimize sedimentation of rivers, streams and drainage structures.
(ii) The following practices shall be incorporated into the plan for erosion and sediment control:
(A) Keep cut and fill operations to a minimum so as to create the least erosion potential;
(B) Retain and protect natural vegetation whenever feasible;
(C) Minimize the exposed ground area and the duration of exposure;
(D) Protect exposed critical areas with temporary vegetation and/or mulching during development;
(E) Trap sediment in runoff water by use of debris basins, sediment basins, silt traps or similar measures until the disturbed area is stabilized;
(F) Prevent surface water from damaging cut and fill slopes;
(G) Locate cuts and fills so as not to endanger adjoining property;
(H) Avoid fills on natural watercourses or constructed channels;
(I) Develop the grading plan so that water is not diverted onto the property of another landowner unless a written agreement allowing such drainage is received from the other landowner; and
(J) Exercise measures for dust control during earthwork operations.
(4) Sewer Plans and Designs.
(i) On-lot sewage disposal systems shall not be permitted within a subdivision, unless this requirement is waived by the board. If this requirement is waived, the on-lot sewage disposal systems shall be designed per applicable standards and technical procedures adopted by the state, or applicable standards of the applicable local sanitation district.
(ii) Sanitary sewer plans shall comply with applicable standards and technical procedures adopted by the state, and applicable standards of the local sanitation district.
(5) Water Supply.
(i) All applicants, provided that the town has the legal and physical supply of water necessary, shall be required to lay pipelines in conformance to standards adopted by the town and to connect with the town water system.
(ii) All water lines shall be laid at the expense of the applicant, including tapping on fees from the nearest supply main that will supply the required water volume as determined by the town, and all water lines shall be looped. There shall be no dead-end water mains.
(6) In the event the owner disagrees with any decision by the town engineer, the owner may appeal such decisions to the board. Such appeal must be filed in writing with the town clerk within 30 days of the date of the town engineer’s decision. [Amended during 2011 recodification; Ord. 719 § 2, 2008. Code 1999 § 17-2-6].