When a detention facility is proposed, the applicant shall submit plans and information, depending on the development size, providing the following data to ensure that the provisions of this Code are met. The submittal shall include sufficient information to evaluate the environmental characteristics of the property, the potential adverse impacts of the development on water resources on-site, upstream, and downstream, and the effectiveness of the proposed drainage plan in managing stormwater runoff. The applicant shall certify on the drawing that all clearing, grading, drainage, and construction shall be accomplished in strict conformance with the drainage plan. The following information shall be submitted for both existing and proposed property conditions.
(A) Properties Smaller Than Five Acres.
(1) Topographic map. A topographic survey of the property and areas upstream and downstream necessary to determine offsite impacts of the proposed drainage plan at one-foot contours.
(2) Environmental features. A depiction of environmental features of the property and immediate vicinity including the following:
(a) The limits of wetland areas;
(b) Any proposed channel modifications;
(c) Any designated natural areas; and
(d) Proposed environmental mitigation features.
(3) Drainage system. A depiction of the existing and proposed drainage system features of the property and immediate vicinity including the following:
(a) The banks and centerline of streams and channels;
(b) Shorelines of lakes, ponds, and detention basins;
(c) Watershed boundaries within the property;
(d) Location, size, and slope of stormwater conduits, including all storm sewers;
(e) Sanitary and combined sewers;
(f) Natural depressional storage areas;
(g) Delineation of upstream and downstream drainage features and watersheds which might be affected by the development;
(h) Existing and proposed detention facilities;
(i) Roads and streets, and their associated drainage structures;
(j) Base flood elevation, floodplain and regulatory floodway limits where identified on the property;
(k) Location and direction of all overland flood routing, and the depth and velocity of flow at critical locations within the drainage system; and
(l) Other pertinent information determined to be necessary by the Chief Inspector of the Board of Fire Prevention.
(B) Properties Larger Than Five Acres. The same information as required in subsection (A) of this Section is required for properties larger than five acres, along with the following additional information:
(1) Elevations and maps of flooding;
(2) Cross-section data for open channel and overland flood paths; and
(3) A statement by the project engineer of the drainage system's provisions for handling events greater than the 100-year runoff.
(Ord. 05-2528, passed 7-26-05)