Ordinance No. 20430 - Laserfiche WebLink

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compacted to a degree that causes their rational method runoff coefficient to exceed 0.8, determined in accordance with the city’s adopted Public Improvement Design Standards Manual. (6) Stream and Channel Crossings. Bridges, culverts or other structures that cross waterways permitted under EC 9.4780(3) shall comply with the following standards: (a) Crossings shall be designed and constructed in a manner that results in the least physical impact to the waterway, utilizing a minimum width, appropriate invert elevations and slope, and aligned at right angles to the waterway whenever practicable; (b) Culverts and bridges shall not increase or decrease water depth, velocity or flow rate upstream or downstream from the culvert, except as necessary to address conveyance needs identified in the city’s adopted Stormwater Management Manual or as otherwise allowed or required by this code; (c) When a culvert 72 inches in diameter or greater would be required, bridges shall be utilized, or box or arch culverts with bottoms filled to a depth of at least 12 inches with stone; and (d) Stream banks and stream beds must be stabilized at crossings, using vegetative bio-engineering methods to the maximum extent practicable. (7) Hydrology. Existing hydrology shall be maintained unless modification of hydrology is an element of an approved use and/or intended to improve water quality to minimize flow concentration, downcutting, and erosion. (8) Stormwater Discharges. (a) Improvements shall not increase or decrease stormwater conveyance capacity either upstream or downstream of improvements except as necessary to address conveyance needs identified in the city’s adopted Stormwater Management Manual, or as otherwise allowed or required by this code; (b) Improvements shall meet the stormwater development standards of EC 9.6790 through EC 9.6797; and (c) Flow spreaders and energy dissipaters shall be utilized to prevent erosive impacts to protected areas from stormwater discharges where practicable to avoid concentrating stormwater discharges. (9) Repair and Reconstruction of Stream Banks and Channels. Bio- engineering methods are to be used to repair stream bank failures and channel erosion problems and to reconstruct stream banks and channels except where those methods by themselves would be ineffective. Where bio- engineering alone is inadequate, stones and boulders may be used to augment bank repair efforts, dissipate energy or control flows. (10) Removal of Materials Harmful to Water Quality. All refuse, toxics, fill, unauthorized auto bodies, or similar materials located within the /WQ Management Area that are harmful to water quality or that limit the filtration of pollutants from runoff that flows across the /WQ Management Area shall be removed. (11) Protect Management Area During Construction. Prior to engaging in the use authorized under EC 9.4780(3), the applicant shall demarcate the /WQ Management Area setback area by a prominent and continuous protective feature indicating a “No Disturbance Area.” No site preparation, including but not limited to vegetation removal, may take place within 50 feet of the /WQ Management Area, until the city has verified the required demarcation. Ordinance - 15