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Subdivision Regulations

ARTICLE 29-28 DESIGN STANDARDS

Section 29-28-1       General Guidelines

  1. Consideration should be given in all Subdivisions to conserve natural features such as trees, watercourses, historical and archaeological sites and similar community assets which add value and beauty to the community.

  2. Adequate access shall be provided from an existing public street to land being subdivided.  Approval of such access shall be a condition of approval of the plat by the Commission and the Council.

  3. Any contiguous property owned by the Subdivider shall not be excluded from the boundaries of a Subdivision when needed or required for traffic, drainage or flood control facility for the Subdivision.

  4. The design of the structural location for building streets, drainage provisions, water supply and sewage disposal, etc., shall be made by an engineer registered in the State of Arizona and qualified to specify the Standards for such design or by an assistant under his supervision.

  5. Any improvements proposed shall conform to this Subdivision Chapter and shall be acceptable to the Town Engineer.

  6. It is the responsibility of the Subdivider to comply with these regulations.

    1. If at any time in the processing of  Subdivision Plat it is found by the staff of Planning and Zoning that these regulations are not being complied with, the Subdivider shall be notified by the staff.

    2. If compliance is made by the Subdivider, processing of the Subdivision shall proceed as if it had been complied with by the Subdivider.

    3. If compliance with these regulations has not been made by the Subdivider within thirty (30) days, a registered letter shall be sent giving the Subdivider fifteen (15) days to comply.

    4. If a reply is not received within fifteen (15) days, the processing of the Subdivision shall be terminated.  Once processing is terminated, a Subdivision must be resubmitted.

  7. The Commission shall not approve the Subdivision as submitted if it has determined that the land is not suitable for the development proposed due to flooding, steep slopes, rock formation or design features likely to be harmful to the safety, welfare and health of the future residents.  The Subdivision processing shall continue if corrective measures are taken and are acceptable to the Commission.

  8. If the Subdivision is traversed by or is adjacent to streams or other bodies of water, the Subdivider shall provide a right-of-way for storm drainage conforming substantially with the line of the natural watercourse or provide an acceptable realignment of the watercourse.

Section 29-28-2       General Street Requirements

  1. The arrangement, character, extent, grade, width and location of all streets shall conform to the Master Town Street Plan.

  2. The arrangement of streets shall provide continuation of existing major streets in surrounding areas.

    1. The center line shall be a continuation of the center line of existing streets and highways in contiguous territory.

    2. Center lines may be continued by curves where straight continuation is not physically possible.

  3. Structures or culverts shall be installed for drainage, access, and public safety.  Adequate drainage of the Subdivision streets and alleys shall be provided with the use of culverts, structures, or other means approved by the Commission.

  4. Adequate provisions shall be made in the design of the Subdivision for access to each lot and to adjacent properties.

  5. Half width streets may be approved in a Subdivision where there is adjacent property that may be developed in the future which can provide the other half width to the street.

    1. The width of a half width street shall not be less than thirty feet (30').

    2. A full width street shall be provided where it would be impractical for half width streets.

  6. Provisions shall be made for existing railroad, public, or private utility crossings to provide access to and circulation within the proposed Subdivision.  This would include obtaining all necessary permits from the public or private utility without cost to the municipality.

  7. The Commission may recommend that a frontage street be provided in cases where a Subdivision fronts on an arterial  street.

  8. Street intersections shall be as nearly at right angles as possible and no intersection shall be less than sixty degrees (60º).

  9. Property line radii at street intersections shall not be less than thirty feet (30') for all streets, and when the angle of the street intersection is less than seventy-five degrees (75º), the Town Engineer may require a greater curb radius.

  10. Concrete curbs shall be installed according to the approved line and grade required by Town Engineering.

  11. A Subdivision that adjoins existing streets shall dedicate additional rights-of-way to meet the dimensional requirements established by the Town and this Chapter.

  12. Proposed streets which are in alignment with other existing named and numbered streets shall be given the designation of the existing street.

    1. The name for the proposed street shall not duplicate those of any existing streets irrespective of the use of suffixes such as Avenue, Road, Boulevard, Drive, Place, Court, or other designation.

    2. The Office of Planning and Zoning shall assist the Subdivider to avoid duplication of street names through the use of its index of street names and numbers.

  13. Alleys are not required but are permitted for all Subdivision lots intended for commercial use.  They shall be no less than twenty feet (20') nor greater than thirty feet (30') in width.

  14. Alleys are not required but are permitted for residential lots and shall be no less than sixteen feet (16') nor more than twenty feet (20') in width, except as required for special design purposes.

  15. Sidewalks are required.  The minimum width for sidewalks in residential areas shall be four feet (4').  The town may require wider sidewalks in commercial areas, by schools or similar areas.

  16. The minimum radius for a vehicular turn-around on a cul-de-sac street shall be determined by the Town Engineer.

Section 29-28-3       Street Standards

The street improvements within the subdivision shall conform to the following standards and requirements.

  1. The street construction shall be fully paved streets with curbs, gutters and sidewalks.  Curb, gutter and sidewalk is required unless specifically excepted by the Thatcher Town Council.

  2. All commercial areas shall be fully paved with curbs, gutters and sidewalks.

  3. Streets shall be constructed in accordance with good engineering practices as well as the following design criteria:

    1. All streets shall be constructed with a centerline grade between 0.3% and 10%.  As an exception, local and cul-de-sac streets may be constructed to a grade up to a 20% but only for a distance of 500 ft. or less.

    2. Culverts may be either concrete or plastic with concrete ends.  They may be either prefabricated or constructed in place as approved by Town Engineering.  Headwalls are required at all ends.  The Town may require additional erosion protection.

    3. The pavement structure shall be designed and  constructed in accordance with standards adopted by the Town of Thatcher.  As a minimum, all streets shall be constructed with 3" of hot-mix asphalt on top of 8" of aggregate base course.

    4. All streets shall be constructed with a minimum crown of 2% from the centerline to the gutter.  Warping of the cross-slope is allowed at intersections, driveways and other similar areas.  However, transitions such as at driveway turnouts will be limited to a 6% maximum change.

    5. No irrigation controls may be located in streets or sidewalks.  All irrigation structures shall be constructed to minimize hazards to motorized vehicles, bicycles, and pedestrians.  All controls shall be fenced off or grated to prevent unauthorized entry.

    6. All sidewalks, footbridges, and other facilities intended to be used by pedestrians must meet ADA standards.

    7. Design conditions for streets shall be as follows: 

Street 
Classification		 Design Speed
(mph)		 Stopping Sight Distance
(ft)
Arterial 50 800
Major 45 600
Collector 40 300
Local 35 150

Posted speed limits will be determined in conjunction with Town staff, but generally will be set at 10 mph less than design.  Design traffic conditions will be coordinated with the Town Engineer.  A Level of Service condition of “C” or better will be used based projected counts at a 20 year horizon.  Minimum count will be an ADT of 500 or 10 per home along a street, which ever is greater.  A traffic study may be required from the developer.  The developer shall indicate the intended classification of streets shown on his plat in a separate letter to the Town Engineer.

8. Signing, striping, and signalization will comply with the Federal Highway Administration Manual of Uniform Traffic Control Devices as approved of by Town Staff.  The developers plans will specifically indicate these elements.

9. Curb and drop inlets will constructed in a manner safe for bicycles and pedestrians.

10. Length of vertical curves (measured in feet) will be a minimum of three times the design speed (measured in mph).  Grade breaks may be used if the total change is less than 0.2% for any design speed.  Longer curves may be required for larger grade differences at higher speeds.

11. The maximum degree of curvature for a horizontal curve shall be 8o00'.  The Town may require milder curves or superelevation.  Superelevation will vary with design speed but shall not exceed a 0.06 ft. per ft. transition rate.

12. A minimum of 16 ft. vertical clearance shall be maintained for any overhead obstructions.  For side clearances, a 2' minimum distance is required on curbed sections and 6' for areas with bare shoulders.

13. Minimum intersection setbacks and spacing between driveways varies with street classification as follows:

Street
Classification		 Spacing
(ft)
Arterial  250
Major 200
Collector 100
Local Direct access to parcels

14. Landscaping on parcels must gradually taper to meet the top of the sidewalk fronting the street at all points.  Developers shall install curbing or retaining walls on the outside of the sidewalk for parcels graded such that landscaping lies above the sidewalk or where landscaping slopes more than 10% within 8 ft. of the sidewalk.

15. Pole-mounted street lights will be installed at all intersections and at a spacing outlined in the Town standards.  Type of pole, mountings, luminare, etc. must also comply with Town standards.

16. Transformers, mail boxes, light poles, and other obstructions must be placed in the utility easement paralleling the street right-of-way or on another easement provided away from the street according to Town standards.

17.  Rolled curbs may be used on local streets, otherwise vertical curb and gutter will be used.  Curbing will comply with Town standards.

  1. The developer shall submit to the Town Engineer all plans, specifications, estimates and engineering reports as required for review to establish that sound principles have been used to prepare for infrastructure construction.  As a minimum, these submittals shall include:

    1. Title sheet, plan-profiles, typical sections, and details outlining existing and proposed street, sewer, drainage, and other improvements as customarily found on engineering drawings.  Plans shall also indicate right-of-ways, easements, monumentation, and utility ownership.  Plans for review will be submitted in duplicate as blue-lines on a standard 24" x 36" paper at an appropriate scale.

    2. A geotechnical report commenting on area features and profiling in at least three places the soil to a depth of 6 ft. calling out the soil type, gradation, compaction test results and plasticity index.  At least one bore will be taken to a depth of 50 ft. to show the above information as well as depth to ground water.  The report shall include recommendations for minimum pavement design.  The developer shall submit a proposed sampling plan commensurate to the size of the development to the Town Engineer for his approval.  Any unusual conditions may require additional investigation.

    3. A drainage report detailing watershed information, storm event selections, and hydrologic and hydraulic calculations for pre-development and post-development conditions.  The report shall outline all proposed work including the construction of storm sewers, basins, and improvements to existing channels.

    4. A construction report with a list of proposed standard specifications and details to be used (ADOT, MAG, PAG, ADWR, etc.) along with estimated quantities and construction cost estimates.  The cost estimates will be compared to the bond amounts when submitted prior to commencement of construction.  Note: The developer shall provide copies of third-party quality control reports to the Town Engineer for all aspects of construction.

    5. All plans and reports shall be stamped by an engineer registered in the State of Arizona.  Survey information must be prepared by and stamped by a Registered Land Surveyor of Arizona.

    6. As-built infrastrucure plans will be submitted to the Town following construction and acceptance on mylar as well as on CAD format for entry into the Town’s CAD data base.  The Town maintains a CAD data base for its own use in mapping and planning future work.  The CAD drawings may be electronic copies without the developer’s engineer’s seal or identifying information.  The Mylar set must be stamped by the developer’s engineer as approved as-builts.  The developer’s engineer shall coordinate with the Town Engineer for CAD formatting.

  2. The minimum Street Standards are summarized in the standards adopted by the Thatcher Town Council resolution:

    STREET TYPE

    		 RIGHT OF  WAY PAVEMENT WIDTH
    Arterial 100 ft. 68 ft.
    Major 84 ft. 64 ft.
    Collector 60 ft. 44 ft.
    Local 50 ft. 42 ft.
    Cul-de-sac 54 ft. 50 ft. R

    Pavement width includes curbs. The town may require the construction of bicycle paths requiring wider sections.

Section 29-28-4       Definitions

In this Chapter unless the context requires otherwise, the street definitions are:

  1. "Arterial" means a contiguous street tying together two (2) or more traffic generating areas, or portions of any officially projected streets, used primarily for through traffic between separate areas to collect and distribute all traffic to any terminal served by the street and to the lesser streets in between.  An arterial street shall be located along all section and major streets along all quarter section lines, except where the terrain dictates otherwise.

  2. "Collector" means a connecting street between two (2) main streets, which does not function as a main street or any street supplementary to a main street, that extends through at least one (1) intersection with other minor streets.

  3. "Cul-de-sac" means a street with only one (1) entrance and with a turn-around at the other end.

  4. Special addresses with varying circumstances such as one-way, frontage or hillsides will be resolved with the Town Engineer.

  5. "Major" means a principal traffic route for contiguous streets which is also a means of access to arterial streets.

  6. "Local" means a street supplementary to either a main street or to a collector street which is terminated in a "T" intersection if the street is less than one quarter (1/4) of a mile in length, a loop street, or a cul-de-sac.

Section 29-28-5       Blocks

  1. A block is any portion of a Subdivision delineated by the streets and the boundary of the Subdivision.

  2. The length, width, and shape of blocks shall be determined with provisions for adequate building sites, zoning requirements, limitations of topography, convenience for pedestrians, access and circulation, control and safety of streets.

  3. A block shall not be more than one thousand three hundred twenty feet (1,320') in length unless the Commission considers it necessary to increase it to secure efficient use of land.

    1. Blocks which are over six hundred sixty feet (660') in length may be required to have crosswalks.

    2. Longer blocks may be provided when fronting on major streets in order to reduce the number of intersections.

  4. A block shall be wide enough to allow two (2) tiers of lots of minimum depth.  The Commission may approve a single tier of lots of minimum depth if` conditions justify it.

Section 29-28-6       Lots

  1. The lot area, width, depth, shape and position shall be appropriate for the location and shall conform to the requirements of this Chapter.

    1. Side lot lines shall be at right angles to straight street lines or radial to curved street lines insofar as practical.

    2. Each lot shall front upon a public street or upon an approved access street.

  2. Each lot shall be accessible to the street which it fronts.  A lot shall be graded, when necessary, to ensure access and adequate use of the property as a condition of approval of the Final Plat.

  3. Each lot shall be suitable for the purpose for which it is intended and shall contain a usable building site.  The area of a lot shall be exclusive of any area designated for streets or easements.

  4. When the land is subdivided into larger parcels than ordinary building lots, such parcels shall be arranged to allow for future streets and Subdivisions that may develop.

  5. Each lot shall be designated by Arabic numerals.

    1. Numbering shall be in a consecutive sequence beginning with the number "1" if block designations are not used.

    2. Continuous consecutive numbering shall follow from one block to another when lots have common side boundaries within a Subdivision or within a block along each street.

    3. Numbering shall be in consecutive sequence within each block commencing with the number "1" for each block when block designations are used.

    4. Numbering sequences may follow in continuity from one Subdivision to another when lying contiguous to one another or when separated if the same name is used for successive Subdivisions.

    5. Parcels shall be designated by capital letters and in sequence within a Subdivision starting with the letter "A".

  6. The lot depth shall mean the horizontal length of a straight line connecting the bisecting points of the front and rear lot lines.

    1. Lots with more than four (4) sides shall have for the side lot lines those contiguous to the front lot line, and a line connecting the center of the remaining lot lines shall be used to measure the lot depth.

    2. Each irregular lot shall have a minimum width at the front and rear setback lines of forty feet (40') and no lot shall be less than one hundred feet (100') in depth.

    3. A lot shall not be designed with a depth to width ratio greater than three to one (3:1) for the usable area, except those lots located on a knuckle or end of a cul-de-sac street may have a four to one (4:1) radio.

  7. Corner lots shall be wider than minimum to provide adequate usable area where lots are designed with minimum areas.

Section 29-28-7       Sanitary Sewage and Water Systems

  1. The requirements for development of public water systems and community sewage disposal systems shall not be less than those required by the Arizona State Department of Health and the Arizona Department of Environmental Quality..

  2. A Subdivider shall indicate the distance to approved refuse disposal areas.  The Council may require disposal facilities to be furnished by the Subdivider before the Subdivision is approved if none are available.

Section 29-28-8       Easements and Utilities

  1. An easement at least twenty feet (20') in width shall be provided adjacent to each rear or side lot line for poles, wires, conduits, sanitary sewers, gas mains, water mains and other utilities except where alleys are provided for that purpose.  If the utilities are to be located in the street right-of-way, then utility easements may be eight feet (8') along each side of street and around cul-de-sac, and ten feet (10') around the perimeter of the Subdivision, provided that said street right-of-way meets Town standards.  The town may stipulate grading, surface preparation, etc., of the easements.

  2. Half (½) of partial easements may only be approved where dedication of necessary additional easements are on record.

Section 29-28-9       Monuments

  1. Monuments shall be a steel pin or pipe at least eighteen inches (18") in length and set in a reasonably permanent manner for all points of reference on the outside boundary at each lot corner or at all points of curvature or tangency of the Subdivision.

  2. Survey monuments shall be required at all street intersections and at the point of curvature and point of tangency of all curves as approved by the Town Engineer when streets are paved.  Brass caps punched by a Registered Land Surveyor set inside cast-iron hand holes embedded in concrete with a lid indicating “SURVEY” will be set at intersections, section corners, and quarter section corners.