(a) Electric transmission lines shall cross floodway fringe and special flood hazard areas by the most direct route feasible. When support towers must be located within floodway fringe or special flood hazard areas, they shall be placed to avoid high flood water velocity and/or depth areas, and shall be adequately flood proofed.

(b) Buried utility transmission lines transporting hazardous materials, including but not limited to crude and refined petroleum products and natural gas, shall be buried a minimum of four feet below the maximum scour of the waterway, as calculated on the basis of hydrologic analyses. Such burial depth shall be maintained within the floodway fringe or special flood hazard area to the maximum extent of potential channel migration as determined by hydrologic analyses. All such hydrologic analyses shall conform to requirements of SCC 30.65.220(6)(c).

(c) Beyond the maximum extent of potential channel migration, utility transmission lines transporting hazardous and non-hazardous materials shall be buried below existing natural and artificial drainage features. Burial depth in all agricultural areas requiring or potentially requiring subsurface drainage shall be a minimum of six feet as measured from ground surface to the top of the transmission line, or at other such depth as deemed necessary by on-site investigations performed by a qualified soils expert familiar with Snohomish County soils. Burial depth in all other agricultural and non-agricultural floodway fringe or special flood hazard areas shall be determined on the basis of accepted engineering practice and in consideration of soil conditions and the need to avoid conflict with agricultural tillage.

(d) All buried utility transmission lines shall achieve sufficient negative buoyancy so that any potential for flotation or upward migration is eliminated.

(e) Above ground utility transmission lines not including electric transmission lines shall only be allowed for the transportation of non-hazardous materials. In such cases, applicants must demonstrate that line placement will have no appreciable effect upon flood depth, velocity, or passage. Such lines shall be adequately protected from flood damage.

(f) Above ground utility transmission line appurtenant structures including valves, pumping stations, or other control facilities shall not be permitted in floodway fringe or special flood hazard areas except where no other alternative is available or in the event a floodway fringe or special flood hazard location is environmentally preferable. In such instances, above ground structures shall be located so that no appreciable effect upon flood depth, velocity or passage is created, and shall be adequately flood proofed.