(A) Any entrance, whether in a rural or urban area, shall not obstruct or restrict the normal water courses involved, unless suitable provisions are made therefore. The Director of Public Works shall be satisfied that the type, size and installation of the drainage features proposed in the application are adequate for present and foreseeable future requirements and have a reasonable life span. As to the type of drainage pipe material, the Director of Public Works shall be governed by the subdivision regulations, latest edition, if replacement under the maintenance policy would involve a hardship to the department. If small pipe is used in the normal ditch and with no large fill, the applicant may make the choice.
(B) Requirements for drainage shall be as follows:
(1) Necessary drainage structures for an entrance shall not be tied onto an existing highway drainage structure unless the necessary junction boxes, manholes, and catch basins are installed by permittee in accordance with county specifications.
(2) The size, length and type of the entrance pipe shall be as required by the Director of Public Works, but in no case shall be less than 12 inches in diameter, and not less than 20 feet in length.
(3) All entrance pipes, whether of corrugated metal, concrete or bituminous coated corrugated metal shall meet appropriate department specifications and requirements. Pipes shall be of sufficient length to prevent end damage. Sloped box inlet or outlet may be required by the Director of Public Works.
(4) Valley gutters constructed of concrete or bituminous material, which meet department standards, may be used in lieu of entrance pipe where the pipe cannot be placed.
(5) (a) Where long lengths of pipe are used, catch basins or clean-out boxes shall be installed at approximate intervals of not less than 100 feet based upon pipe diameter of 12 inches.
(b) Special consideration may be given to placement of clean-out boxes at longer intervals for pipe with larger diameters. Boxes shall also be constructed at all angles in pipe alignment.
(6) When necessary, gratings and catch basins must be employed to intercept and prevent water flowing from the driveway over the sidewalks or roadway.
(7) Utilities are not to be placed in or through existing drainage conduits.
(8) When a fill is to be placed against an existing roadway, the fill shall be constructed to intersect the outside shoulder edge and slope away from the road on a 6:1 slope to the ditch flow line or a depth of three feet. Furthermore, special drainage features as required by the Director of Public Works, shall be required of the applicant to adequately drain the road bed and shoulders. This refers to french drains or toe drains in the existing fill.
(9) Occasionally, underpavement drainage is provided by sand, crushed stone or other types of drains from the pavement through the shoulder of the road. Requests to join the pavement at these existing drainage points must be accompanied by plans showing the methods proposed to extend these drains so that their original purpose will be continued. This provision is applicable to commercial and private entrances.
(10) Any proposal to alter or significantly increase a drainage area, runoff factors or change in any way a drainage structure must be accompanied by a complete drainage survey (upstream and downstream) based upon a 25-year and 100-year storm with hydraulic analysis of all affected drainage structures in the area.
(Ord. 620.11, passed 8-29-95) Penalty, see § 97.99