Skip to main content
Loading…
This section is included in your selections.

The following standards apply only as specifically required by EC 9.4930(3) or EC 9.8030(21).

(1) Enhancement. Where the /WR conservation area is reduced, or uses are approved within the /WR conservation area, the remaining /WR conservation area shall be enhanced consistent with this subsection and by removing non-native plant species and planting native plant species consistent with subsections (2) and (3) below.

(a) All refuse, toxic materials and any fill that limits or decreases the capacity of the conservation setback area to filter pollutants from runoff that flows across the conservation setback area shall be removed (not including stormwater collected and discharged from impervious surfaces).

(b) Where practicable, finished grades shall encourage sheet flow of runoff across conservation setback areas to maximize filtering and infiltration of precipitation and runoff within conservation setback areas (not including stormwater collected and discharged from impervious surfaces).

(c) On sites where the slope within the conservation setback area exceeds 15 percent, measures (e.g., planting and contouring) shall be taken to slow the flow of runoff to the maximum extent practicable (not including stormwater collected and discharged from impervious surfaces).

(d) Non-native plants shall be permanently removed to the maximum extent practicable and replaced with native plant species in accordance with subsection (3) below.

(e) Except as required by EC 9.4980(2)(c), EC 9.4980(3)(d) and EC 9.4980(3)(e), site work to enhance the conservation setback area shall be completed prior to or concurrent with other site development, unless appropriate native plant species are not available within that time frame.

(2) Vegetation Removal. Vegetation removal within the /WR conservation area and within areas removed from the /WR conservation area shall comply with the following standards:

(a) Vegetation removal shall be limited to:

1. Plant species that are non-native and invasive;

2. Dead or dried native plants or grasses only when they constitute an imminent fire hazard;

3. Living native or non-native vegetation, when its removal is necessary to facilitate or encourage the growth of other native species (e.g., native wet prairie plant species) consistent with adopted plans or policies; or

4. The minimum area of native vegetation removal necessary to accommodate uses approved in accordance with EC 9.4930(3)(a) through EC 9.4930(3)(k), and uses approved through an adjustment approved in accordance with EC 9.8030(21).

(b) Clearing of more than 500 square feet of vegetation must comply with Erosion Prevention regulations for sensitive areas in EC 6.645.

(c) Any clearing of vegetation that is not within the footprint of uses approved in accordance with EC 9.4930(3)(a) through EC 9.4930(3)(k), or uses approved through an adjustment approved under EC 9.8030(21), must be followed by replanting in accordance with the requirements of subsection (3) below.

(3) Planting and Replanting. Planting or replanting within the /WR conservation area shall comply with the following standards:

(a) Areas of existing bare soil and areas which have been cleared or graded in accordance with subsection EC 9.4980(2) or EC 9.4980(5) shall be planted with native plant species. Except as required in (b) and (c) below, plant species and plant spacing used for such plantings shall be appropriate to increasing to the greatest extent practicable the capacity of the conservation setback area to filter pollutants from runoff that flows across the conservation setback area (not including stormwater collected and discharged from impervious surfaces). Where existing native vegetation already serves this function to some extent, additional native plants shall be planted in order to augment native vegetation already existing. Plant species selected for all plantings shall be appropriate to the site given its topography, hydrology, soil, and existing native plant species.

(b) Planting or replanting within 25 feet of a Category B, C, or D stream within the /WR conservation area shall include native tree or large shrub species and located so as to provide substantial shading of the channel during times of peak solar input.

(c) Where non-native or damaged trees are removed within 25 feet of a Category B, C, or D stream within the /WR conservation area, they shall be replaced with native tree or large shrub species and located so as to achieve equal or greater shading of the channel during times of peak solar input as the trees removed.

(d) Replanting of areas cleared of existing vegetation must be completed within 90 days following the removal or clearing, unless otherwise approved by the planning director.

(e) Plantings shall not adversely affect adjacent protected water resources or existing native vegetation through shading or invasion by plant species introduced into the setback.

(4) Construction Practices. Construction within the /WR conservation area, and within areas removed from the /WR conservation area shall comply with the following standards:

(a) For purposes of this subsection, heavy machinery is defined as motorized or mechanized machinery or equipment capable of deliberately or inadvertently damaging vegetation, or damaging or compacting soil. The following standards shall apply to use of heavy machinery within the /WR conservation area:

1. On sites where soils are susceptible to severe compaction or structural damage when wet or saturated, use of heavy machinery shall be limited to the period between June 15 and September 30, unless otherwise approved by the planning director.

2. Use of heavy machinery shall be the minimum necessary for the use or activity and shall be restricted to those areas where its use is necessary.

(b) Petroleum products, chemicals, or other deleterious materials used in the construction process shall not be allowed to enter a stream or wetland that is within a /WR conservation area.

(5) Filling, Grading and Excavating. Filling, grading and excavating within the /WR conservation area and within areas removed from the /WR conservation area shall comply with the following standards:

(a) Filling, grading or excavating of more than 500 square feet must comply with Erosion Prevention regulations for sensitive areas in EC 6.645.

(b) Grading and excavating conducted as part of restoration or enhancement projects, and bank and channel reconfiguration shall result in topography that resembles landscapes shaped only by natural processes, for example, incorporating the undulations, meanders and slopes found in such landscapes. For purposes of this standard, straight lines and geometric or angular shapes are not acceptable. Channel and stream bank slopes shall not exceed 25 percent at elevations of 500 feet or less.

(6) Impervious Surfaces. Within the /WR conservation area, construction of new impervious surfaces shall comply with the following standards:

(a) Impervious surfaces are prohibited within the /WR conservation area unless they are part of a use approved in accordance with EC 9.4930(3).

(b) Impervious surfaces that are part of a use approved in accordance with EC 9.4930(3) shall be no larger than the minimum necessary for the approved use. For sites with wetlands, impervious surfaces shall be located as far from the boundaries of locally significant wetlands as practicable. For riparian and upland wildlife habitat sites, impervious surfaces shall be located as far from the line of ordinary high water as practicable.

(c) Durable porous paving treatments or other infiltration devices approved by the planning director or decision-maker shall be used in lieu of standard impervious paving surfaces to increase infiltration of stormwater where practicable. This standard shall apply only to low volume parking areas, foot paths or lightly used access roads, where porous soils and flat topography will facilitate infiltration of runoff. For the purposes of this subsection, gravel surfaces are not acceptable as porous paving or as an infiltration device.

(7) Site Layout. On sites where the /WR conservation area is reduced, high intensity uses within the entire development site, including high volume traffic lanes and truck loading docks, shall be designed and located so that adverse impacts to wetland and riparian habitats within the /WR conservation area are minimized to the greatest extent practicable.

(8) Lighting. Within the /WR conservation area, and within areas removed from the /WR conservation area, outdoor area lighting shall be prohibited, except to illuminate walkways, bike paths, pedestrian gathering areas, and parking areas, where these facilities are intended to be used after dark. Outdoor area lighting is lighting designed to illuminate an outdoor activity area, trail or bicycle path. Where lighting is to be provided within the /WR conservation area and within areas removed from the /WR conservation area, the following standards shall apply:

(a) Illumination for walkways, pathways or pedestrian gathering areas shall be no more than an average maintained luminance of 0.5 foot-candle at grade.

(b) Output from all other light sources shall be no more than an average maintained luminance of 0.9 foot-candle at grade.

(c) All lighting fixtures shall be designed to direct light downward to areas intended for human use after dark, and shall be shielded such that light shining toward /WR conservation areas is minimized to the maximum extent practicable.

(9) Trails. Within the /WR conservation area, trails shall be constructed of gravel, wood chips or other pervious material, unless otherwise approved by the city manager or decision-maker. Trail construction shall involve the least removal of native vegetation practicable for the area and the minimum amount of fill or excavation practicable.

(10) Stream and Channel Crossings. Bridges or other structures that cross streams or wetlands within the /WR conservation area or areas removed from the /WR conservation area shall be constructed so that water flow, vegetation growth and movement of aquatic animals and water dependent wildlife are impeded to the least extent practicable. To meet this standard, bridges and crossings shall include, but are not limited to, applicable items from the following list:

(a) Bridges across Category A or Category B streams as identified in the Goal 5 Water Resources Conservation Plan shall, where practicable, be designed to avoid channel constriction when flows reach the top of high bank. Where practicable, bridges shall span a distance 1.2 times the width of the stream channel from top of high bank to top of high bank to help prevent scouring within the structure or at the outlet during less frequent floods.

(b) Crossings over Category A or Category B streams as identified in the Goal 5 Water Resources Conservation Plan shall utilize bridges or natural substrate culverts where possible. Where practicable, the lower lip of any natural substrate culvert shall be embedded at least 1 foot for box culverts and pipe arches, and at least 25% of the pipe diameter for pipe culverts. The substrate within the structure shall match the composition of the substrate in the natural stream channel at the time of construction. The substrate shall either resist displacement during flood events or the structure shall be designed to maintain an appropriate bottom through natural bed load transport.

(c) Bridges and culverts on Category A or Category B streams as identified in the Goal 5 Water Resources Conservation Plan shall be constructed so that the “openness ratio” of the structure is equal to or greater than 0.25. The “openness ratio” is the cross-sectional area of the passage area under or within the structure divided by the length of the stream segment it crosses over. For a box culvert, the openness ratio shall be (height x width)/length.

(d) Culverts shall not substantially increase or decrease water depth or flow rate conditions upstream or downstream from the culvert.

(e) The lower lip of all culverts shall meet the stream or channel bed at or below grade.

(f) Culverts shall be the minimum length practicable, and fill on top of the culvert shall have the minimum footprint practicable.

(11) Interpretive Facilities. Within the /WR conservation area, boardwalks, viewing platforms, interpretive information kiosks, trail and interpretive signs shall be constructed in a manner that involves the least removal of native vegetation practicable. Signs shall be no more than 5 feet tall, and 16 square feet per face in surface area, except for signs intended to be read from moving automobiles, such as site entrance signs, which shall be no more than 8 feet tall and 32 square feet per face in surface area. Kiosks shall be no more than 8 feet tall and 16 square feet per face in surface area. The number of signs shall be the minimum necessary to accomplish project objectives.

(Section 9.4980 added by Ordinance No. 20351, enacted November 14, 2005, effective January 1, 2006; administratively corrected November 27, 2006.)