(A) The permanent alteration of the significant natural resource by grading, by excavation or fill, by the placement of structures or impervious surfaces, or by the removal of native vegetation is prohibited, except for the following uses provided they are designed to minimize intrusion into the significant natural resource, and no other options or locations are feasible:
(1) Public or private streets, driveways or paths may be placed within a significant natural resource to access development activities if it is shown to the satisfaction of the reviewing authority that no other practicable method of access exists. If allowed, the applicant shall comply with the following requirements:
(a) Demonstrate to the reviewing authority that no other practicable access to the buildable area exists or access from an off-site location through the use of easements is not possible;
(b) Design roads, driveways and paths to be the minimum width necessary and for the minimum intrusion into the significant natural resource while also allowing for safe passage of vehicles and/or pedestrians;
(c) Use bridges, arched culverts or box culverts with a natural bottom for crossing of a significant natural resource if the crossing is found unavoidable. The lower lip of any culvert must meet the channel bed at or below grade. The number of channel crossings shall be minimized through use of shared access for abutting lots and access through easements for adjacent lots;
(d) Consider the need for future extensions of shared access, access easements or private streets to access potential new building sites at the time of this application in order to avoid subsequent encroachments into the significant natural resource;
(e) Prior to construction, the significant natural resource area shall be flagged, fenced or otherwise marked and shall remain undisturbed, except as allowed by the provisions of this subchapter. Such markings shall be maintained until construction is complete;
(f) During construction, no stockpiling of fill materials, parking or storage of equipment shall be allowed within the significant natural resource;
(g) Erosion control measures, such as silt fences and bio-filter bags, shall be used to reduce the likelihood of sediment and untreated storm water entering the significant natural resource; and
(h) Permanent alteration of the significant natural resource by the placement of public or private streets, driveways or paths is subject to the mitigation requirements hereof.
(2) Public and private utilities or drainage facilities may be placed within a significant natural resource when it is shown to the satisfaction of the review body that no other practicable alternative location exists. If a utility or drainage facility is allowed within a significant natural resource, the following standards shall apply:
(a) Demonstrate to the reviewing authority that no other practicable access exists or access from an off-site location through the use of easements is not possible;
(b) The corridor necessary to construct utilities shall be the minimum width practical so as to minimize intrusion into the significant natural resource. Removal of trees and native vegetation shall be avoided unless absolutely necessary. The existing grade of the land shall be restored after construction. Native vegetation shall be used to restore the vegetative character of the construction corridor;
(c) Prior to construction, the significant natural resource area shall be flagged, fenced or otherwise marked and shall remain undisturbed, except as allowed by the provisions of this subchapter. Such markings shall be maintained until construction is complete;
(d) During construction, no stockpiling of fill materials, parking or storage of equipment shall be allowed within the significant natural resource; and
(e) Erosion control measures, such as silt fences and bio-filter bags, shall be used to reduce the likelihood of sediment and untreated storm water entering the significant natural resource.
(3) Replacement of existing structures with structures in the same location that do not disturb additional surface area;
(4) Structures or other non-conforming alterations existing fully or partially within the significant natural resource may be expanded; provided, the expansion occurs outside of the significant natural resource. Substantial improvement of a non-conforming structure in the significant natural resource shall require compliance with the standards of this subchapter;
(5) Existing lawn within the significant natural resource may be maintained, but not expanded within the limits of the significant natural resource. Development activities shall not justify replacement of native vegetation, especially native riparian vegetation, with lawn;
(6) Existing bank stabilization and flood control structures may be maintained. Any expansion of existing structures or development of new structures shall be evaluated by the Planning Department and appropriate state or federal natural resource agency. Such alteration of significant natural resources shall be approved only if less-invasive or non-structural methods, such as bioengineering, will not adequately meet stabilization or flood control needs; and
(7) The types, sizes and intensities of lights must be placed so that they do not shine directly into the significant natural resource.
(B) Removal of vegetation from the significant natural resource is prohibited, except for:
(1) Removal of non-native vegetation and replacement with native plant species. The replacement vegetation shall cover, at a minimum, the area from which vegetation was removed, shall maintain or exceed the density of the removed vegetation, and shall maintain or improve the shade provided by the vegetation;
(2) Removal of vegetation necessary for the continued maintenance of dikes, drainage ditches, or other storm water or flood control facilities. Vegetation removal shall be kept to the minimum necessary;
(3) Trees in danger of falling and thereby posing a hazard to life or property may be removed, following consultation from a certified arborist and approval from the Planning Department. If no hazard will be created, the Department may require these trees, if felled, to be left in place in the significant natural resource; and
(4) The control or removal of nuisance plants should primarily be by mechanical means (such as, hand-pulling). If mechanical means fail to adequately control nuisance plant populations, a glyphosate-based herbicide is the only type of herbicide that can be used in a significant natural resource area. No pre-emergent herbicides or auxin herbicides that pose a risk of contaminating water should be used. A herbicide application is preferred to be made early in the morning or during windless periods at least four hours before probable rainfall.
(Prior Code, § 16.75.015)