The following standards apply only as specifically required by EC 9.4780(3):
(1) Vegetation Removal. Vegetation removal in order to accommodate a use listed in EC 9.4780(3) shall comply with the following standards:
(a) Vegetation removal in excess of that allowed by EC 9.4780(2)(b) shall be the minimum necessary to accommodate the use; and
(b) Any clearing of vegetation that is not within the footprint of uses approved in accordance with EC 9.4780(3), or uses approved through an adjustment approved under EC 9.8030(25), must be followed by replanting in accordance with the requirements of subsection (2) below.
(2) Planting and Replanting. Planting or replanting of areas that are cleared or graded in order to accommodate a use listed in EC 9.4780(3) and that are located outside of the use’s footprint shall comply with the following standards:
(a) Plantings of plants and vegetation provided they are not Invasive, Non-Native Plant species as defined in EC 9.0500 Definitions, including some tree or large shrub species and planted in sufficient quantity and location to provide bank stability and to create substantial shading of the channel during times of peak solar input;
(b) Except as required in (d) below, the plant species and plant spacing to be utilized shall further the objective of increasing, to the greatest extent practicable, the capacity of the /WQ Management Area to filter pollutants from runoff that flows across the /WQ Management Area;
(c) Plant species selected for all plantings shall be appropriate to the site given its topography, hydrology, and soil type;
(d) Areas of bare soil existing as a result of vegetation removal shall be protected or covered consistent with EC 6.625 through EC 6.645, and replanted or mulched and seeded with straw mulch and native seed within 15 days of disturbance;
(e) Disturbed areas shall be re-planted consistent with this section as soon as practicable, but no later than March15 of the calendar year following disturbance; and
(f) A 70% survival rate of plantings shall be guaranteed for a 3-year period in the form of a financial deposit, bond or other means sufficient to cover the cost to remove dead and dying species, and to purchase and replant with living species. City staff shall be granted access to the planted area by the property owner as a condition of approval for this use in order to monitor the establishment of the plantings during this 3-year period.
(3) Construction Practices. Construction to accommodate a use listed in EC 9.4780(3) shall comply with the following standards:
(a) Construction, maintenance, repair, reconstruction and restoration activities shall be planned and timed so as to minimize adverse impacts to water quality;
(b) 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 /WQ Management Area:
1. The 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;
2. The use of heavy machinery within the channel shall be limited to the period between June 15 and September 30 except as allowed by permit from the Army Corps of Engineers or Oregon Department of State Lands; and
3. On sites where soils are severely compacted through the use of heavy machinery, the soils shall be tilled or re-tilled to a depth of 6 inches.
Construction may also be subject to construction site management practices such as the erosion prevention provisions of EC chapter 6, which apply to, among other things, clearing, grading, grubbing, excavation and filling.
(4) Utility Alignment. Routing of new utility lines to accommodate a use listed in EC 9.4780(3) shall be designed so as to minimize adverse impacts to water quality within the /WQ Management Area to the greatest extent practicable.
(5) Paved Surfaces. Construction of new paved surfaces to accommodate a use listed in EC 9.4780(3) shall comply with the following standards:
(a) Impervious surfaces shall be minimized by constructing the facility or infrastructure with as little impervious surface as allowed by city standards and the Americans With Disabilities Act;
(b) Impervious surfaces shall be located as far from the waterway as practicable; and
(c) For paved foot paths, lightly used access roads, or low volume parking areas where soils and flat topography will facilitate infiltration of runoff, pervious pavement systems, or other infiltration devices approved by the planning director or city engineer shall be used in lieu of standard impervious paving surfaces to increase infiltration of stormwater where practicable. For the purposes of this subsection, gravel surfaces are considered pervious unless they cover impervious surfaces or are compacted to a degree that causes their rational method runoff coefficient to exceed 0.8, determined in accordance with the city’s adopted Public Improvement Design Standards Manual.
(6) Stream and Channel Crossings. Bridges, culverts or other structures that cross waterways permitted under EC 9.4780(3) shall comply with the following standards:
(a) Crossings shall be designed and constructed in a manner that results in the least physical impact to the waterway, utilizing a minimum width, appropriate invert elevations and slope, and aligned at right angles to the waterway whenever practicable;
(b) Culverts and bridges shall not increase or decrease water depth, velocity or flow rate upstream or downstream from the culvert, except as necessary to address conveyance needs identified in the city’s adopted Stormwater Management Manual or as otherwise allowed or required by this code;
(c) When a culvert 72 inches in diameter or greater would be required, bridges shall be utilized, or box or arch culverts with bottoms filled to a depth of at least 12 inches with stone; and
(d) Stream banks and stream beds must be stabilized at crossings, using vegetative bio-engineering methods to the maximum extent practicable.
(7) Hydrology. Existing hydrology shall be maintained unless modification of hydrology is an element of an approved use and/or intended to improve water quality to minimize flow concentration, downcutting, and erosion.
(8) Stormwater Discharges.
(a) Improvements shall not increase or decrease stormwater conveyance capacity either upstream or downstream of improvements except as necessary to address conveyance needs identified in the city’s adopted Stormwater Management Manual, or as otherwise allowed or required by this code;
(c) Flow spreaders and energy dissipaters shall be utilized to prevent erosive impacts to protected areas from stormwater discharges where practicable to avoid concentrating stormwater discharges.
(9) Repair and Reconstruction of Stream Banks and Channels. Bio-engineering methods are to be used to repair stream bank failures and channel erosion problems and to reconstruct stream banks and channels except where those methods by themselves would be ineffective. Where bio-engineering alone is inadequate, stones and boulders may be used to augment bank repair efforts, dissipate energy or control flows.
(10) Removal of Materials Harmful to Water Quality. All refuse, toxics, fill, unauthorized auto bodies, or similar materials located within the /WQ Management Area that are harmful to water quality or that limit the filtration of pollutants from runoff that flows across the /WQ Management Area shall be removed.
(11) Protect Management Area During Construction. Prior to engaging in the use authorized under EC 9.4780(3), the applicant shall demarcate the /WQ Management Area setback area by a prominent and continuous protective feature indicating a “No Disturbance Area.” No site preparation, including but not limited to vegetation removal, may take place within 50 feet of the /WQ Management Area, until the city has verified the required demarcation.