Levee Alternative 1 Sample Clauses

Levee Alternative 1. ‌ With Levee Alternative 1, approximately 11,820 feet of levee would be constructed around the north, west, and south sides of the city of Amenia to provide flood protection to residents during a 100-year, 24-hour event, as shown in Appendix B. South Xxxxxxxx Avenue (155th Avenue SE) currently protects the east side of Amenia from floods of this magnitude. Levee Alternative 1 would be constructed with a top elevation of 959.00 feet above mean sea level (MSL), a base that varies between 40–80 feet wide with a 10-foot top and 4:1 side slopes. A 10-foot-wide channel would be constructed approximately 15 feet from the toe of the levee. The channel is necessary to convey water that currently flows along County Highway 32 through town around the levee as to not create pockets of standing water against the levee toe. A 15-foot clear zone would be maintained on the interior of the levee. Trees would not be allowed on the levee or in the clear zone as tree roots can compromise the integrity of levees over time. A stormwater pond would be developed for Levee Alternative 1 to capture floodwaters and runoff from approximately 180 surface acres within the levee system. The pond for Levee Alternative 1 would cover an area 300 feet by 500 feet with a depth of 16 feet—8 feet for a permanent pool and 8 feet for bounce or fluctuation in water surface elevation, also known as live storage volume. The 8 feet of live storage assumes water levels in the pond would bounce 5 feet for a coincident 100-year event while allowing 3 feet of freeboard. This pond would be connected to a storm lift station. During normal events, gravity drainage would occur through gate well structures with sluice gates, and the lift station would not be utilized. During a flood, the gate well structures would be closed, and gravity flows would be diverted to the pond and pumped through the lift station to remove internal drainage. The lift station would be designed to pump at a peak capacity of 28 cubic feet per second (cfs), based on the capacity of existing culverts. The permanent pool of water would allow for stormwater treatment to improve water quality. The larger volume from the pond excavation would provide additional material for the proposed levee construction. Approximately 100,150 cubic yards (CY) of material would be required to construct the levee embankment. Material for levee construction would be derived on site, with approximately 67,000 CY obtained through excavation of the stormwater ...