A.    Stormwater runoff resulting from a proposed development shall be detained on-site:

    1.    By wet or dry bottom reservoirs;

    2.    By underground reservoirs;

    3.    On flat roofs, parking lots or streets, or

    4.    By other detention methods approved by the city engineer.

    B.    For purposes of designing adequate on-site detention facilities, the Illinois State Water Survey rainfall data for this region shall be used. (Ord. 1320 § 1 (part), 1995: prior code § 5-7-1(C), (D))