(a) All utility transmission lines shall cross floodways by the most direct route feasible as opposed to paralleling floodways;

(b) Electric transmission lines shall span the floodway with support towers located in flood fringe areas or beyond. Where floodway areas cannot be spanned due to excessive width, support towers shall be located to avoid high flood water velocity and/or depth areas, and shall be adequately floodproofed;

(c) 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 established scour of the waterway, as calculated on the basis of hydrologic analyses. Such burial depth shall be maintained horizontally within the hydraulic floodway to the maximum extent of potential channel migration as determined by hydrologic analyses. In the event potential channel migration extends beyond the hydraulic floodway, conditions imposed upon floodway fringe and special flood hazard areas shall also govern placement. All hydrologic analyses are subject to acceptance by the county, shall assume the conditions of a 100-year frequency flood as verified by the U.S. Army Corps of Engineers, and shall include on-site investigations and consideration of historical meander characteristics in addition to other pertinent facts and data. The use of riprap as a meander containment mechanism within the hydraulic floodway shall be consistent with the county shoreline management program;

(d) Buried utility transmission lines transporting non-hazardous materials including water and sewage shall be buried a minimum of four feet below the maximum established scour of the waterway as calculated on the basis of hydrologic analyses. Such burial depth shall be maintained horizontally within the hydraulic floodway to the maximum extent of potential channel migration as determined by hydrologic analyses. All hydrologic analyses shall conform to requirements in subsection (6)(c) of this section. The use of riprap as a meander containment mechanism within the hydraulic floodway shall be consistent with the county shoreline management program;

(e) 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 county soils. Burial depth in all other agricultural and non-agricultural floodway 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;

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

(g) Above ground utility transmission lines, not including electric transmission lines, shall only be allowed for the transportation of non-hazardous materials where an existing or new bridge or other structure is available and capable of supporting the line. When located on existing or new bridges or other structures with elevations below the level of the 100-year flood, the transmission line shall be placed on the down-stream side and protected from flood debris. In such instances, site specific conditions and flood damage potential shall dictate placement, design and protection throughout the floodway. Applicants must demonstrate that such above ground lines will have no appreciable effect upon flood depth, velocity or passage, and shall be adequately protected from flood damage. If the transmission line is to be buried except at the waterway crossing, burial specifications shall be determined as in subsection (6)(d) of this section;

(h) All floodway crossings by utility transmission lines transporting hazardous materials shall be equipped with valves capable of blocking flow within the pipeline in the event of leakage or rupture. All floodway crossings shall have valves unless otherwise indicated by standard engineering review of the site and type of transmission line as acceptable to the county with locations determined by other provisions of this chapter;

(i) Above ground utility transmission line appurtenant structures including valves, pumping stations, or other control facilities shall not be permitted in the floodway; and

(j) Where a floodway has not been determined by preliminary Corps of Engineers’ investigations or official designation, a floodway shall be defined by qualified engineering work by the applicant on the basis of a verified 100-year flood event.

(a) The new farmhouse is a replacement for an existing farmhouse on the same farm site;

(b) There is no potential building site for a replacement farmhouse on the same farm outside the designated floodway;

(c) The farmhouse being replaced shall be removed, in its entirety, including foundation, from the floodway within 90 days after occupancy of the new farmhouse;

(d) For substantial improvements, and replacement farmhouses, the elevation of the lowest floor of the improvement and farmhouse respectively, including basement, is one foot higher than the base flood elevation;

(e) New and replacement water supply systems, are designed to eliminate or minimize infiltration of flood waters into the system;

(f) New and replacement sanitary sewerage systems are designed and located to eliminate or minimize infiltration of flood waters into the system and discharge from the system into the flood waters;

(g) All other utilities and connections to public utilities are designed, constructed, and located to eliminate or minimize flood damage;

(h) The replacement farmhouse shall not exceed the total square footage of encroachment of the structure which it is replacing; and

(i) Repairs, reconstruction, or improvements to a farmhouse shall not increase the total square footage of encroachment of the existing farmhouse.

(a) When residences other than farmhouses are substantially damaged in the floodway, the floodplain administrator may make a written request to the Department of Ecology under RCW 86.16.041(4) to assess the risk of harm to life and property posed by the specific conditions of the floodway. Based on analysis of depth, velocity, flood-related erosion, channel migration, debris load potential, and flood warning capability, the Department of Ecology may exercise best professional judgment in recommending to the floodplain administrator authority to permit repair, replacement, or relocation of the substantially damaged structure. The property owner shall submit any information necessary to complete the assessment to the county and the Department of Ecology. Without a favorable recommendation from the Department of Ecology for the repair or replacement of a substantially damaged residential structure located in the regulatory floodway, no repair or replacement is allowed under WAC 173-158-076(1).

(b) Before the repair, replacement, or relocation is started, all applicable requirements of the National Flood Insurance Program, chapter 86.16 RCW, chapter 30.43C SCC, and this chapter must be satisfied. In addition, the following conditions must be met:

(a) Adverse effects upon adjacent properties will not result relative to increased floodwater depths and velocities during the base flood or other more frequent flood occurrences;

(b) Natural drainage ways are minimally affected in that their ability to adequately drain floodwaters after a flooding event is not impaired; and

(c) The proposal has been coordinated through the appropriate diking district where applicable, and that potential adverse effects upon other affected diking districts have been documented.