A. Embankment Ponds:
1. Foundation Cutoff ("Core-Trench"): A cutoff of relatively impervious material shall be provided under the dam, unless a layer of such material exists at the surface of the foundation. The cutoff shall be thick enough to provide stability and extend along the centerline as required and be deep enough to extend into a relatively impervious layer. The cutoff trench shall have a bottom width and side slopes (minimum 1:1) to accommodate construction and compaction equipment.
2. Earth Embankment:
a. Top Width: The minimum top width shall be eight feet (8') for dams fifteen feet (15') or less in height and ten feet (10') for those over fifteen feet (15').
b. Side Slopes: The combined upstream and downstream side slopes of the settled embankment shall be not less than five horizontal to one vertical (5:1) with neither slope steeper than three to one (3:1).
c. Freeboard: The minimum elevation of the top of the settled embankment shall be one foot (1') above the water surface in the reservoir with the emergency spillway flowing at design depth, but in all cases, the top of the dam must be two feet (2') above the emergency spillway crest.
d. Compaction: The embankment shall be placed in six inch (6") layers and compacted by heavy equipment such as rubber tired scrapers and tractors or sheepfoot rollers.
3. Principal Spillway:
a. Pipe Conduit:
(1) A pipe conduit with needed appurtenances shall be placed under or through the embankment/dam.
(2) The capacity of the pipe conduit shall be adequate to discharge long duration, continuous or frequent flows without earth spillway flow. The minimum diameter of the pipe shall be twelve inches (12").
b. Anti-Seep Collars:
(1) Anti-seep collars shall be installed around the pipe conduit, drainpipes and water supply pipes within the normal saturation zone. The anti-seep collars and their connections to the pipe shall be watertight.
(2) A minimum of one anti-seep collar shall be provided on conduits of fifty feet (50') or less in length. On longer conduits, proper collars shall be provided approximately every twenty five feet (25') in the saturated zone. Collars will normally extend two feet (2') outside the pipe, except for eight inch (8") pipe collars which may be only four feet (4') square, and water supply pipe collars, two feet (2') square.
c. Trash And Safety Guards: Trash guards shall be installed unless the design technician determines that a trash guard is not needed. Vertical risers larger than fifteen inches (15") in diameter shall have a safety guard installed.
d. Outlets: All pipes thirty inches (30") or larger shall be dropped with flowline elevation two (2) to four feet (4') above the outlet channel. Smaller pipes shall be dropped unless the Village determines the drop is not needed.
e. Drainpipe: A drainpipe shall be installed with a suitable valve where needed for pond management. Ponds for fish production with three (3) acres or more of surface area will be equipped with a pipe large enough to drain the pond in a fourteen (14) day period. A pumping system of adequate size, which is available, will meet this requirement.
4. Spillways: The minimum capacity of natural or constructed emergency spillways shall be that required to pass the "100-year" storm flow. Emergency spillways shall be designed for safe velocities through the control channel and a reasonable distance below. The minimum size spillway is ten foot (10') bottom width with three to one (3:1) side slopes. Wing dikes or shaped exit channel shall be constructed of such materials as needed to ensure that spillway flows do not cause erosion or damage the earth embankments. (1977 Code § 4-6-6; amd. 2004 Code)
B. Excavated Ponds:
1. Water Supply: The supply of water may be entirely from surface runoff, from subsurface sources, from an intermittent or continuous stream or from a combination of these sources.
2. Side Slopes: Side slopes of excavated ponds shall be such that they will be stable and shall not be steeper than three horizontal to one vertical (3:1).
3. Inlet Protection: Where surface water enters the pond, the side slopes shall be protected against erosion.
4. Specifications:
a. The completed excavation shall conform to the lines, grades, and elevations shown on the plans as nearly as can be achieved by proper operation of the excavating equipment.
b. The material excavated from the pond shall be deposited as follows so that its weight will not endanger the stability of the pond side slopes and will not be washed back into the pond by rainfall:
(1) Uniformly spread to a height not exceeding three feet (3'), with the top graded to a continuous slope away from the pond, minimum slope on pond side of three to one (3:1); or
(2) Uniformly placed or shaped reasonably well with wide slopes assuming the natural angle of repose for the excavated material but not less than three to one (3:1) behind a berm width equal to the depth of the pond but no less than twelve feet (12'). (1977 Code § 4-6-7)