A. Where authorized by the village administrator, an underdrain system may be installed in lieu of the roadside ditch, and shall be constructed in accordance with the following standards unless otherwise approved by the village administrator.

B. Pipe material shall conform to Illinois Department of Transportation Standard Specifications for Road and Bridge Construction for pipe culverts type 1A. The underdrain shall be sized adequately to handle the drainage area to be served and shall be at least equal in diameter to the nearest crossroad culvert serving the drainage area. In no case, however, shall an underdrain of less than twelve inches in diameter be installed. The minimum pipe slope shall be 0.20%.

C. Each lot shall have, at a minimum, an inlet structure on the downstream end of the underdrain. Additional inlet structures shall be required, at the direction of the village administrator, when necessary to prevent the obstruction of other drainageways or to prevent ponding. Each inlet structure shall be constructed with an inside dimension of two feet by two feet square. It shall be constructed on block or brick and mortar with a minimum wall thickness of four inches where walls are eighteen inches high or less. If greater than eighteen inches high, the wall thickness shall be eight inches. It shall be set on Portland cement concrete with a minimum thickness of six inches. The inlet shall be covered with a frame and grate suitable for use in streets or trafficways (similar to Neenah Foundries No. R3405 or approved equal). The surface of the grate shall be laid flush with the flow line of the new surface drainage swale so as to deposit all surface waters from the adjacent road and lot area into the underdrain system.

D. Culvert pipe on the upstream end of the underdrain shall be connected to any existing inlet structure. If no inlet structure exists on the upstream end, the ground at the upstream end shall be sloped from the new surface drainage swale with a slope not steeper than three feet horizontal to each vertical foot. The ground on the downstream side of a downstream inlet structure, if no adjoining underdrain exists, shall be similarly sloped. If a downstream inlet structure exists between two driveways, as shown on Exhibit B, attached to the ordinance codified in this section and copies of which are on file in the office of the village clerk, and insufficient spare exists between the inlet structure and the downstream driveway to accommodate the required slope, then the underdrain leading from the inlet structure shall be connected to the existing downstream driveway culvert, and the entire area between the driveways shall be filled and graded so that the surface of the inlet structure grate is flush with the new surface drainage swale.

E. All areas disturbed in the course of this construction shall be repaired to their original condition and all waterways shall be hand raked and seeded as directed by the village administrator.

F. All work and materials used on the village right-of-way shall be in accordance with the Standard Specifications for Road and Bridge Construction as well as Exhibit B, attached to the ordinance codified in this section and copies of which are on file in the office of the village clerk. (Ord. 1978-12 § 2, 1978)