The stormwater submittal shall include a narrative discussion and calculations to support a finding by the qualified review specialist that the proposed development complies with the technical requirements of this subchapter. The submittal shall consist, at a minimum, of the following material.
(A) Narrative description of the existing and proposed site drainage patterns and conditions, including description of offsite conditions that help to identify stormwater issues considered in the design.
(B) Schedule for implementation of the site stormwater plan.
(C) Onsite and offsite runoff calculations that address the following:
(1) Documentation of the procedures and assumptions used to calculate hydrologic and hydraulic conditions for sizing major and minor systems;
(2) Cross-section data for open channels;
(3) Hydraulic grade line and water surface elevations under design flow conditions; and
(4) Hydraulic grade line and water surface elevations under base-flood-flow conditions.
(D) Site runoff storage calculations that address the following:
(1) Calculation of hydraulically connected impervious area and corresponding retention volume;
(2) Documentation of the procedures and assumptions used to calculate hydrologic and hydraulic conditions for determining the allowable release rate;
(3) Documentation of the procedures and assumptions used to calculate hydrologic and hydraulic conditions for determining the storage volume;
(4) Elevation-area-storage data and calculations for site runoff storage; and
(5) Elevation-discharge data and calculations specifically related to the outlet control structure depicted in the plan exhibits.
(Ord. 2019-03, passed 4-15-2019)