§ 30-277. General design standards.

(a)

A stormwater management system shall be designed and installed for the development that will contain features to provide for:

(1)

Pollution abatement (Categories 1, 2 and 3).

(2)

Recharge, where possible (Category 3 only).

(3)

Rate of discharge limitations (Categories 2 and 3).

(4)

Protection from flooding (Categories 2 and 3).

(b)

These requirements may be waived for individual sites within commercial or industrial subdivisions which have provided master drainage systems.

(c)

Pollution abatement will be accomplished by retention, or detention with filtration, of one-half inch of runoff from the developed site, or the runoff generated from the first one (1) inch of rainfall, on the developed site. The volume of runoff generated from the first inch of rainfall shall be estimated by multiplying the Rational Method Runoff Coefficient (C) for the developed site by one (1) inch of rainfall.

(d)

Recharge in areas where the soils are compatible (Hydrologic Soil Group Type "A" soils as described by the U.S.D.A. Soil Conservation Service) will be accomplished by providing for retention of the total runoff generated by a twenty-five-year frequency, twenty-four-hour duration storm event from the developed site.

(e)

The post development peak rate of discharge permitted from the site will not exceed the predevelopment peak rate of discharge from the site during a twenty-five-year frequency storm event. Those sites with no positive outfall will be required to retain total runoff from a one-hundred-year storm event.

(f)

All residential structures are to be flood-free and all commercial and industrial structures are to be either flood-free or floodproofed (see section 30-279).

(Code 1965, § 32-66(b); Ord. No. 86-20, § 1(b), 8-25-86; Ord. No. 91-29, § 2(Exh. A), 12-10-91)