(A) To minimize the need for future bank stability measures, the City Engineer may require geotechnical or geomorphological studies of Streams prior to approval of Development plans or building permits for any structure to be located adjacent to a Stream. Such studies may be used to increase the Stream Corridor width requirement and could include the designation of the maximum expected natural Channel migration, analyses of slope stability, and foundation analysis of adjacent structures. At a minimum, for slope stability and foundation analysis purposes, it will be assumed Streams migrate at least one half the distance of the minimum Stream Corridor indicated in 17.06.050; provided, however, the same studies may also be required to be performed assuming the maximum Channel migration has occurred. The City Engineer is authorized but not required to issue technical guidance to assist Applicants in making this estimate of Channel migration potential.

(B) The use of rip-rap, retaining walls, gabions, revetments or other bank armoring techniques shall not be used to reduce the Stream Corridor boundaries established in 17.06.050. Such activities are allowed only when the City Engineer determines them to be necessary to protect structures, primarily when Stream migration has exceeded the original estimate of natural Channel migration. The City Engineer may allow bank stabilization measures that are designed to incorporate natural Channel features and vegetation in situations where projects will enhance the value of the Stream Corridor and minimize the likelihood of more extreme measures being needed at a later time. (Ord. 09-25 § 2, 2009.)