Subdivision Improvement Plan Checklist

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Yellow Explanation Point.png This list is contains information that is typical to most developments. This list does not necessarily contain all the information that needs to be addressed on all developments. It has been created more as a guideline/aid in the design process.

Utility Requirements

  • Existing utilities are to be shown on the plans

Culinary Water

  • A letter from the culinary water provider shall be provided stating that that are satisfied with the design and it meets their requirements.
  • Proper clearance from sewer lines shall be provided
  • Fire hydrants shall comply with requirements of the Weber County Fire Department.
  • Culinary water lateral locations


  • Fencing around irrigation ditches

Land Drain

  • Land drain systems are to be owned and maintained the the homeowners association or another owner, whom is not the County.
  • Developments may have limited basement depths depending on water table level.

Road Section

  • Asphalt thickness shall not be less than 3 inches.
  • A minimum of 8” of 4” minus sub-base and 6” road-base.
  • Compaction test will be required for the base, sub-base, and any fill.

Secondary Water

  • Health Department may require pressurized secondary system to prevent flooding of drain field
  • Water District may require secondary system to prevent primary usage as irrigation
  • Secondary Water lateral locations


  • A letter from the sewer district shall be provided stating that that are satisfied with the design and it meets their requirements.
  • Gravity flow is always prefered.
  • Physical constraints (verify with state rules)
    • Check location
    • Size
    • Depth
    • Proximity to waterlines
  • Manholes
    • Every 400', change in grade, direction
    • Four-foot diameter on line
    • Five-foot diameter on intersection
    • Benching required
  • Septic Systems
    • Drain fields must be >100' from a drainage ditch and wells unless the ditch is piped with gaskets

Storm Drain

  • Design: 10 year storm for initial collection and conveyance. 2 hour storm approximately: 0.97 - 1.10 in. Varies throughout the county. Use the NOAA website.
  • Detention Facility
    • Runoff shall not exceed 0.1 cfs/acre.
    • Basin shall have adquate capacity.
    • Direct discharge (pipes) into receiving water is not acceptable. Provide some cleaning, i.e. desilting, holding time.
  • Sheet flow discharge may be acceptable
  • Catch basins must be specified, or catch basin detail must be included
  • Culverts
    • RCP 15" min. in roadways
    • RCP 12" min. in driveways
    • Canal crossings must have written approval from the applicable canal company.
    • County pipe projects must have at least 50' of pipe [(7) 8' pipes = 56']
  • A Notice of Intent (NOI) is required for coverage under the Utah Pollutant Discharge Elimination System (UPDES) Storm Water General Permit.
    • A SWPPP is required prior to obtaining the NOI.

Plan Requirements

Curb & Gutter, Sidewalk

  • Required for all commercial
  • Planning can defer these requirements
  • All subdivision with less than 1 acre lots require C&G
  • Sidewalk is required in the proximity of an Elementary School

Curve Data

  • All curve data should be shown for the centerline of the road
  • Back of Curb data should be shown, usually at intersections


  • Check for proper drainage (no ponding)
  • Check for traffic design
  • Check max. 8% slope on major streets
  • Check max. 12% slope on minor streets
  • Check max. 15% slope on private streets
  • Check max 4% slope on cul-de-sacs
  • Check 4-5% slope at intersections for approximately (2) two car lengths
  • Are cut and fill easements required?
  • Check driveway designs
  • Check that utilities are within ROW
  • Cul-de-sacs radii: 55' in upper valley, 50' in lower valley
  • Must make provisions to continue existing streets in adjoining areas
  • Minor streets approach major streets at angle of not less than 80º.
  • Major streets: 86 feet, minor streets: 66 feet
  • Private streets: not less than 50 feet
  • Minor terminal streets (cul-de-sac): 650' or may serve 14 lots max
  • Max. length of 2000' to beginning of turnaround for design

Street Names

  • Check that what is on the Plat is not left off the improvement drawings

Temporary turnaround

  • Roads which are proposed to go straight through and are currently more than one lot deep must have a cul-de-sac turnaround

General Requirements

Excavation Permit

  • These are required if and when new utilities tie into existing utilities in the ROW.
  • Water, sewer, storm drain, etc.


  • Street centerline monuments
  • Survey monuments (rebar & cap)


  • Developer may want to insist on submitting reproducible for as-builts (see subdivision ordinance).
  • The as built improvement plans should be on Mylar and PDF.


  • Required for dead-ends, intersections, etc.
  • Developer pays for signs & road department installs them
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