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<br /> <br />47 <br /> <br />4. Existing and proposed structures, fill, pavement, and other impervious surfaces, and <br />locations for storage of hazardous materials; <br />5. Existing native vegetation and proposed clearing limits; and <br />6. If the proposed development involves grading, excavation, or filling, include proposed <br />post-development terrain at one (1) foot contour intervals. <br /> <br />17A.05.050 Compensatory Mitigation Requirements. <br />1. Floodplain storage. If development occurs within a frequently flooded area, the volume of <br />space occupied by the authorized fill or structure below the base flood elevation shall be <br />compensated for and balanced by a hydraulically equivalent volume of excavation taken <br />from below the base flood elevation. Compensatory storage shall comply with KCC <br />14.08.315 and the following: <br />a. Provide equivalent volume at equivalent elevations to that being displaced. For this <br />purpose, “equivalent elevation” means having similar relationship to ordinary high <br />water and to the best available ten (10)-year, fifty (50)-year, and one hundred (100)- <br />year water surface profiles; <br />b. Provide flood storage that is hydrologically connected to the source of flooding; <br />c. Provide flood storage in an area that is vegetated; <br />d. Consider the existing and future ecological hydrologic functions of the impact and <br />mitigation sites; <br />e. Result in no net rise of flood elevations (when the mitigation will occur at a distance <br />from the fill location); <br />f. Areas below the waterline of a pond or other body of water cannot be credited as <br />compensatory storage; <br />g. Provide flood storage in the same construction season as when the displacement of <br />flood storage volume occurs and before the flood season begins; and <br />h. If the newly created storage area is accessible to fish during flood events, the area <br />shall be designed, graded, and maintained to prevent fish stranding. <br />2. Floodplain storage site selection. The order of preference for selecting floodplain storage <br />sites shall be: <br />a. Onsite flood storage; <br />b. Off-site flood storage in close proximity upstream or downstream of the floodplain fill <br />location; and <br />c. Off-site flood storage in a location further upstream or downstream of the floodplain <br />fill location. <br />3. Floodplain storage mitigation plans. When required by KCC 17A.05.050.2, floodplain <br />storage mitigation plans shall be prepared by an engineer or geologist licensed in the state of <br />Washington and address the general mitigation plan requirements of KCC 17A.01.080 as <br />well as the following: <br />a. Potential that materials may be swept during flooding onto other lands to the <br />detriment of others; <br />b. Actual danger to life and property if flooding or erosion occurs; <br />c. Susceptibility of the proposed development and its contents to flood damage; <br />d. Availability of alternative locations for the proposed development which are not <br />subject to flood or erosion damage; <br />e. Relationship of the proposed development to any comprehensive flood hazard <br />managements plans adopted pursuant to RCW Chapter 86.12; <br />f. Safety of access to the property in times of flooding for ordinary and emergency <br />vehicles; <br />g. Expected heights, velocity, duration, rate or rise, and sediment transport of the flood <br />waters and the effects of wave action at the site; <br />h. Costs of providing governmental services during and after flood conditions, including <br />maintenance and repair of public utilities and facilities;