1121.03 MISCELLANEOUS ENGINEERING DETAILS.
(a) Drainage. The subdivider shall provide all necessary facilities to assure complete drainage in and adjacent to his property. The subdivider shall submit all drainage calculations along with a topographic map showing all areas tributary to the overall drainage system and to the actual street drainage.
Storm drainage shall not be permitted to empty into any sanitary sewer system.
The storm water in the drainage system shall be determined by the subdivider using a ten-year storm frequency and suitable run off factors for completed development both within the subdivider's property and all lands upstream from the subdivider's property. If the design storm flow is calculated in an amount which can be conducted adequately by a forty-eight inch conduit or less, then the developer shall install a conduit of sufficient capacity up to forty-eight inches in size to conduct this drainage on and through the subdivider's property. If the design flow is calculated in amount in excess of the capacity of a forty-eight inch conduit, then the subdivider must provide a conduit or an open drainage channel treatment designed as follows:
(1) Open channels with grades less than one and one-half percent (1.5%) shall have the sides and bottom protected by seeding and mulching, Item 659. Riprap, Item 601, shall be furnished and installed as required.
(2) Open channels with grades between one and one half percent (1.5%) and four percent (4%) shall have the sides and bottom protected by sodding, Item 660. Riprap, Item 601, shall be furnished and installed as required.
(3) Open channels with grades in excess of four percent (4%) shall have the sides and bottom protected by reinforced Portland cement concrete, Item 601.
The subdivider shall provide easements for all storm water conduits or open channels located on privately owned property.
Where a public storm water sewer is reasonably accessible or has been planned and financed, as determined by the engineer of jurisdiction, the subdivider shall extend and connect with such storm water sewer and shall provide such channel or conduit and appurtenances as are necessary in accordance with other stipulations of the Subdivision Code.
There shall be sufficient inlets on any conduit system, as substantiated by the engineer, to provide adequate surface drainage. All trenches for water lines, sewers, laterals, utilities, etc. within the pavement or driveway areas shall be backfilled and compacted with granular material meeting Item 310, subbase, or Item 411, stabilized crushed aggregate, to a point three feet outside the back of curb.
All circular conduits shall be reinforced concrete pipe with sealed joints or smooth interior corrugated polyethylene storm sewer pipe. The minimum diameter shall be not less than twelve inches. Where special drainage designs are necessary such as masonry or concrete structures, etc., such designs in detail shall be submitted to the engineer of jurisdiction for approval in advance of the completion of the construction plans.
(b) Flood Plain. If any portion of the land within the subdivision is subject to inundation or flood hazard by a storm water, such fact and that portion shall be clearly indicated on the subdivision plat. Land subject to flooding shall not be platted for residential occupancy or for other such uses which may increase the danger to health, life or property or may aggravate the flood hazard.
(c) Intersection. The minimum curb radius shall be twenty-five feet measured to the back of curb. An area of clear vision free of shrubbery, trees and all other obstructions at street intersection shall be provided.
(d) Driveways. The maximum grade on driveways shall not exceed twelve percent (12%). A residential drive shall have a minimum width of sixteen feet at the curb and ten feet at the back of sidewalk. The drive section between the curb and sidewalk shall be a minimum of six-inches Portland cement concrete Item 452, or six inches stabilized crushed aggregate, Item 411 plus two and one-half inches asphalt concrete surface, Item 404.
(e) Sidewalks. Sidewalk shall be composed of a minimum of four-inch thickness of Portland cement concrete except at drives the thickness shall conform to the drive thickness. The sidewalk shall be a minimum of four feet wide. The inside edge shall normally be placed at least five feet from the face of curb and the outside edge no closer than one foot to the right-of-way line.
(f) Underdrains. Six-inch diameter pipe underdrains installed a minimum of three feet below subgrade shall be required under all pavement in order to provide satisfactory subgrade drainage. The estimate of quantities shall include the necessary materials to provide this underdrain under all pavement.
(g) Guard Rail and Seeding, etc. The necessity of guard rail, seeding, type of backfill or other special conditions, shall be determined with the assistance of the engineer of jurisdiction or his representative before completion of the construction plan.
(h) Cul-de-sac. The paved area within the circular space at the termination of the cul-de-sac shall have a minimum radius of thirty-five feet.
(i) T-Turn Arounds. T-turn arounds may be required by the City Planning Commission as a temporary measure at the end of streets where a future extension is anticipated into adjacent land.
The location and design of T-turn arounds shall be determined with the assistance of the engineer of jurisdiction or his representative. The T-turn arounds shall extend the entire width of the right of way and shall have a minimum width of fifteen feet along the property line with the flared portions rounded by a minimum radius of fifteen feet.
(Ord. 06-282. Passed 12-19-06.)