§ 92-10. Contents of stormwater plan.  


Latest version.
  • (a)

    Plan presentation.

    (1)

    Through plans, illustrations, reports, and calculations, the stormwater plan shall display the required information specified in subsection (d).

    (2)

    The stormwater plan must be sufficiently detailed to specify the type, location, and size of stormwater management facilities, using preliminary calculations. Detailed construction drawings are not required at the stormwater plan review stage.

    (3)

    If it is proposed to develop a parcel in two or more phases, the stormwater plan shall be prepared and submitted for the total project.

    (b)

    Plan preparation. The stormwater plan shall be prepared by a registered civil engineer. Other persons and professionals may assist in the preparation of the plan.

    (c)

    Scale for mapping. The stormwater plan shall be drawn to a scale as at a reasonable engineering scale to show the details on 24" x 36" drawings. For parcels one acre or less a scale of 1" = 20' is required, and for sites larger than one acre, the plans shall not exceed 1" = 50' with an overall plan for the entire development not being smaller than 1" = 200' in scale.

    (d)

    Required information.

    (1)

    The location by means of a small location map, drawn to a scale no less than 1" = 2,000'.

    (2)

    Zoning classification of petitioner's parcel and all abutting parcels.

    (3)

    The location and description of all on-site features and all adjacent off-site features within 100 feet, and all other off-site features that may be impacted in determining the overall requirements for the development. This includes:

    a.

    Existing site topography with contours at two-foot intervals or less based on the NAVD88 datum, unless the site has less than four feet in vertical elevation change, which will require one-foot contours.

    b.

    Adjoining roads and developments.

    c.

    Railroads.

    d.

    High tension power lines or underground transmission lines.

    e.

    Cemeteries.

    f.

    Parks.

    g.

    Natural and artificial watercourses, wetlands and wetland boundaries, environmental feature boundaries, 100-year floodplains and 500-year floodways as defined by FEMA, lakes, bays, existing stormwater storage facilities, conveyance swales (natural or artificial) with identification of permanent water elevations.

    h.

    Location of woodlands.

    i.

    Designated natural areas.

    j.

    Any proposed environmental mitigation features.

    k.

    Drains, sanitary and storm sewers, and water mains.

    l.

    Existing and proposed easements.

    m.

    A map, at the U.S.G.S. scale, showing the drainage boundary of the proposed development and its relationship with existing drainage patterns.

    n.

    Boundaries of any off-site drainage area contributing flow to the development.

    o.

    Any watercourse passing through the development, along with the following:

    1.

    Area of upstream watershed and current zoning.

    2.

    Preliminary calculations of runoff from the upstream area for the 100-year 24-hour design storm, for fully developed conditions according to the current land use plan for the area.

    p.

    Soil borings may be required at various locations including the sites of proposed retention/detention and infiltration facilities, and as needed in areas where high groundwater tables or bedrock near the surface exist.

    q.

    Proposed site improvements including lot divisions and building footprints.

    r.

    Preliminary stormwater BMP information including:

    1.

    Location of all stormwater BMPs.

    2.

    Identification of stormwater quality and quantity treatment facilities and method of stormwater conveyance.

    3.

    Preliminary sizing calculations for stormwater quality and quantity, including preliminary estimates of runoff volume captured by BMPs, e.g., infiltration losses, for treatment facilities.

    4.

    Preliminary tributary area map for all stormwater management facilities indicating total size and average runoff coefficient for each subarea.

    5.

    Analysis of existing soil conditions and groundwater elevation and bedrock depth (including submission of soil boring logs) as required for proposed retention and infiltration facilities.

    s.

    Preliminary landscaping plan for stormwater BMPs.

    t.

    Preliminary easements for stormwater management facilities.

    u.

    Required natural features setbacks.

    v.

    Drinking water wells, public wellheads, wellhead protection areas (WHPAs), underground storage tanks, and brownfields.

    w.

    Preliminary maintenance agreement. Any areas of unique geological formations, i.e., karst areas.

(Ord. No. 2017-17 , 11-6-17)