When a detention facility is required or proposed, the applicant shall submit plans and information, depending on 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 both on-site and downstream, and the effectiveness of the proposed drainage plan in managing stormwater runoff. The applicant shall certify on the drawings 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) Proposed channel modifications;
(c) Any designated natural areas; and
(d) Proposed environmental mitigation features.
(3) Drainage system. A depiction of existing and proposed drainage system features of the property and immediate vicinity including:
(a) The banks and centerline of streams and channels;
(b) Shoreline of lakes, ponds, and detention basins;
(c) Farm drains and tiles;
(d) Watershed boundaries within the property;
(e) The property's location within stream or river watersheds;
(f) Location, size, and slope of stormwater conduits;
(g) Sanitary or combined sewers;
(h) Mapped natural depressional storage areas;
(i) Delineation of upstream and downstream drainage features and watersheds which might be affected by the development;
(j) Detention facilities;
(k) Roads and streets and associated stormwater inlets;
(l) Base flood elevation, and regulatory floodway where identified for the property;
(m) Basis of design for the final drainage network components; and
(n) Other pertinent information determined to be necessary by the Comptroller.
(B) Properties larger than ten acres. The same information as required in division (A) of this section is required for properties larger than ten acres along with the following additional information for the minor drainage system's design runoff event and the 100-year runoff event of critical duration:
(1) Elevations and maps of flooding;
(2) Cross-section data for open channel flow paths;
(3) Direction of storm flows;
(4) Flow rates and velocities at critical points in the drainage system; and
(5) A statement by the project engineer of the drainage system's provisions for handling events greater than the 100-year runoff.
(Ord. 7-28, passed 5-9-07
; Am. Ord. 8-70, passed 7-16-08)