(1) Purpose. The purpose of EC 9.6791 is to protect life and property from flood and drainage hazards by maintaining the capacity of the city’s stormwater conveyance system through the establishment of flood control regulations for stormwater runoff. These standards are also intended to ensure that urban stormwater discharged into Junction City Water Control District’s flood control system meets the assigned downstream capacity of the District’s system.
(2) Applicability and Exemptions.
(a) Except as provided in EC 9.6791(2)(b), flood control standards apply to all development permit applications and land use applications.
(b) The standards in EC 9.6791(3) do not apply to development permit applications where the proposed development will be served by a flood control facility that is a manmade drainage system designed to accommodate stormwater run-off generated by the stormwater basin area.
(a) Stormwater flood control facilities shall be designed and constructed according to adopted plans and policies, and in accordance with standards in EC Chapters 6 and 7, and the stormwater flood control provisions and the facility design requirements set forth in the Stormwater Management Manual.
(b) Based on the Rational Method flow calculation, stormwater runoff from the development site for the flood control design storm shall be:
1. Discharged into existing stormwater flood control facilities that, considering all developments that have received tentative or final plan approval as of the date the applicant submits a complete application, have the capacity to handle the stormwater runoff; or
2. Retained or detained onsite; or
3. Discharged into a new stormwater flood control facility constructed by the applicant.
(c) For development proposed within the area shown on Map 9.6791(3)(c) Special Stormwater Flood Control Area Map, the post-development peak flow rate shall not exceed the pre-development peak flow rate for the applicable flood control design storm unless the applicant submits documentation from Junction City Water Control District that the proposed flow rate is acceptable.
(4) Underground Injection Control Systems. Stormwater runoff discharged in underground systems is also regulated through the federal Underground Injection Control (UIC) program under Part C of the Safe Drinking Water Act (42 U.S.C. § 300, Chapter 6A, Subchapter XII) and Oregon Administrative Rule Chapter 340, Section 044.