- MINIMUM REQUIREMENTS FOR INTERNAL (SITE) DRAINAGE
Planning and Zoning Code,
City of Hedwig Village,
Chapter 8, 16, 19 and 21.)
1. Subsurface internal drainage must be provided for all tracts larger than 15,000 square feet in area and/or having a depth, measured normal to the
street, greater than 150 feet. Tracts 15,000 square or small and 150 feet or less in depth may be graded to surface drain to existing gutters or roadside ditches (upon review and approval of the Building Official)
provided such grading does not result in draining any part of the area onto adjacent private property.
2. Site grading and drainage plans shall include the following:
a. Be prepared by a Registered Professional Engineer (Seal and Signature).
b. Total area of the site to be drained.
c. Area drained to each inlet.
d. Contours or an adequate number of spot elevations to indicate area to be drained to each inlet.
e. Top elevation and flowline elevation at each inlet.
f. Flowline elevation at outlet (and ditch flowline elevation if appropriate.
g. Gradient on each drain line.
h. Sufficient contours or spot elevation (original and final) around perimeter of site to indicate extent of any filling or excavation. Cut
or fill over 6" requires a retaining wall, over 12" requires an approved design.
3. Computation to support pipe sizes and grades shown.
4. The minimum size of drain pipes shall be 8" diameter.
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