“Applicant” shall mean the individual, partnership, association or corporation applying for a permit to do the work under this chapter and includes property owners, employees, agents, consultants, contractors and successors in interest.

“Approval” means approval by the designated permit authority for clearing, grading and stormwater management.

“Area of special flood hazard, Zone A” means the land in the floodplain within the City subject to a 1 percent or greater chance of flooding in any given year, but where no base flood elevations were determined. Designated on maps as Zone A.

“Area of special flood hazard, Zone AE” means the land in the floodplain within the City subject to a 1 percent or greater chance of flooding in any given year, as determined by a detailed flood insurance study. These areas are subdivided into elevation zones with base flood elevations (“BFEs”) assigned.

“Best management practices” or “BMPs” means schedules of activities, prohibitions of practices, general good housekeeping practices, pollution prevention and educational practices, maintenance procedures, and structural or managerial practices to prevent or reduce the discharge of pollutants directly or indirectly to stormwater, receiving waters, or stormwater conveyance systems. BMPs also include treatment practices, operating procedures, and practices to control site runoff, spillage or leaks, sludge or water disposal, or drainage from raw materials storage.

“Bioretention” means an engineered facility that stores and treats stormwater by passing it through a specified soil profile, and either retains or detains the treated stormwater for flow attenuation. Refer to the stormwater design manual for bioretention BMP types and design specifications.

“Civil engineer” means a professional engineer licensed by the State of Washington in civil engineering.

“Clearing” means the act of destroying or removing vegetation by mechanical or chemical means.

Development. See definition for “New development” or “Redevelopment project” or both.

“Director” means the Director of the Development Services Department or his or her designee.

“Ditch” means an artificially constructed watercourse designed to convey storm water, agricultural runoff or irrigation water. A stream or water of the State that has been artificially constructed or modified is not a ditch. Also see definition of “Stream.”

“Drainage” means the collection, conveyance, containment and/or discharge of surface and stormwater runoff.

“Drainage facility” means a constructed or engineered feature that collects, conveys, stores or treats surface and stormwater runoff. Drainage facilities shall include, but not be limited to, constructed or engineered streams, pipelines, channels, ditches, gutters, stormwater flow control or water quality BMP/treatment facilities, infiltration facilities, erosion and sediment control facilities and other structures and appurtenances that provide for drainage.

“Drainage review” means an evaluation by City of Issaquah permit review staff of a proposed project’s compliance with the drainage requirements in the stormwater design manual, references in the stormwater design manual such as basin plans and critical drainage areas, other requirements stated in this chapter, other applicable requirements of the Issaquah Municipal Code including the critical areas regulations (Chapter 18.802 IMC), and conditions of development or environmental permits issued for the project.

Ecology Stormwater Management Manual. See “Stormwater design manual.”

“Environmentally critical lands” include, but are not limited to, the following:

“Excavation” means the physical, manmade removal of earth material.

“Existing grade” means the land surface elevation prior to grading activity.

“Existing site” means the site prior to any clearing and grading activity or any site prior to the passage of the ordinance codified in this chapter.

“Fill” means a deposit of earth material placed by artificial means which increases the ground surface elevation.

“Finished grade” means the land surface elevation of the site after alterations are completed.

“Flood insurance study” means an examination, evaluation, and determination of flood hazards and, if appropriate, corresponding water surface elevations, or an examination, evaluation, and determination of mudslide (i.e., mudflow) and/or flood-related erosion hazards. Also known as the flood elevation study.

“Flow control facility” means a drainage facility designed to mitigate the impacts of increased surface and stormwater runoff generated by site development pursuant to the drainage requirements in this chapter. Flow control facilities are designed either to retain water for a considerable length of time and then release it by evaporation, plant transpiration and/or infiltration into the ground or to detain runoff for a short period of time and then release it to the conveyance system.

“Grade” means the vertical elevation of the ground surface.

“Grading” means any act which changes the elevation of the ground surface.

“Green belt” means an open area which may be landscaped or maintained in a natural state surrounding development or used as a buffer between land uses or maintained as the edge of an urban or developed area.

“Grubbing” means the act of root vegetation removal from beneath the ground surface.

“Impervious surface” means a nonvegetated surface which either prevents or retards the entry of water into the soil mantle as under natural conditions prior to development or that causes water to run off the surface in greater quantities or at an increased rate of flow from the flow present under natural conditions prior to development. Common impervious surfaces include, but are not limited to, roofs, walkways, patios, driveways, parking lots, storage areas, areas which are paved, graveled or made of packed or oiled earthen materials or other surfaces which similarly impede the natural infiltration of surface and stormwater. Open, uncovered retention/detention facilities shall not be considered as impervious surfaces for purposes of determining whether the thresholds for the application of minimum requirements are exceeded. Open, uncovered retention/detention facilities shall be considered impervious surfaces for purposes of runoff modeling.

“Low-impact development” means a stormwater management and land use management strategy that strives to mimic predisturbance hydrologic processes of infiltration, filtration, storage, evaporation, and transpiration by emphasizing conservation, use of on-site natural features, site planning, and distributed stormwater management practices that are integrated into a project design.

“Low-impact development best management practices” means distributed stormwater management practices, integrated into a project design, that emphasize predisturbance hydrologic processes of infiltration, filtration, storage, evaporation and transpiration. LID BMPs include, but are not limited to, bioretention, rain gardens, permeable pavements, roof downspout controls, dispersion, soil quality and depth, vegetated roofs, minimum excavation foundations, and water reuse.

“Low-impact development principles” means land use strategies that emphasize conservation, the use of on-site natural features, and site planning to minimize impervious surfaces, soil disturbances, native vegetation loss, and stormwater runoff.

“Maintenance” means repair and maintenance activities conducted on currently serviceable structures, facilities, and equipment that involves no expansion or use beyond that previously existing and results in no significant adverse hydrologic impact. It includes those usual activities taken to prevent a decline, lapse, or cessation in the use of structures and systems. Those usual activities may include replacement of dysfunctional facilities, including cases where environmental permits require replacing an existing structure with a different type structure, as long as the functioning characteristics of the original structure are not changed. In regard to stormwater facilities, maintenance includes assessment to ensure ongoing proper operation, removal of built up pollutants (i.e., sediments), replacement of failed or failing treatment media, and other actions taken to correct defects as identified in the maintenance standards of Volume V – Appendix A BMP Maintenance Tables of the 2019 Stormwater Management Manual for Western Washington (SWMMWW).

“Minimum requirements” refers to the minimum requirements in the stormwater design manual.

“Native growth protection easement (NGPE)” means an easement granted to the City for the protection of native vegetation within a critical area or its associated buffer.

“New development” means land disturbing activities, including Class IV general forest practices that are conversions from timber land to other uses; structural development, including construction or installation of a building or other structure; creation of hard surfaces; and subdivision, short subdivision and binding site plans, as defined and applied in Chapter 58.17 RCW. Projects meeting the definition of redevelopment shall not be considered new development.

“Off-site analysis” means a professional assessment of a development or redevelopment project to evaluate the potential impacts of drainage from the site and due to existing system deficiencies, storms in excess of the design storm, or climate change. The off-site analysis would identify, when needed, a plan of measures, mitigation, adaptation, and resilience strategies to minimize to probable impacts of a drainage failure to the new project site and minimize aggravating existing problems. The OAR will assess the mechanism and causes for failure, the probable impacts, including flooding, property damage, business or activity disruption, or transportation impacts, the potential magnitude, and measures to minimize probable impacts.

“Permit” means a permit authorizing clearing, grading and stormwater management, issued as part of a site work permit, building permit, landscaping permit, or as a component of any other permit that authorizes land disturbance.

“Permit authority” means the Director of the Community Planning and Development Department or her or his designee. He/she may designate subordinates to make approvals, sign permits and carry out other responsibilities in application of this chapter.

“Permittee” means the person(s) or entity to whom a permit is issued for clearing and/or grading purposes.

“Pervious surface” means a surface material that allows stormwater to infiltrate into the ground. Examples include lawn, landscape, pasture, native vegetation areas, and permeable pavements.

“Pollution-generating impervious surface” means an impervious surface considered to be a significant source of pollutants in surface and stormwater runoff. Such surfaces include those subject to vehicular use, industrial activities, or storage of erodible or leachable materials, wastes or chemicals and which receive direct rainfall or the run-on or blow-in of rainfall. Thus, a covered parking area would be included if runoff from uphill could regularly run through it or if rainfall could regularly blow in and wet the pavement surface. Metal roofs are also considered pollution-generating impervious surface unless they are treated to prevent leaching.

“Pollution-generating pervious surface” means a nonimpervious surface considered to be a significant source of pollutants in surface and stormwater runoff, including surfaces subject to use of pesticides and fertilizers, to the use or storage of erodible or leachable materials, wastes or chemicals or to the loss of soil. Such surfaces include, but are not limited to, permeable pavement subject to vehicular use, lawn and landscaped areas including golf courses, parks and sports fields (natural and artificial).

“Redevelopment project” means, on a site that is already substantially developed (defined as having 35 percent or more of existing hard surface coverage), the creation or addition of hard surfaces; the expansion of a building footprint or addition or replacement of a structure; structural development including construction, installation or expansion of a building or other structure; replacement of hard surface that is not part of a routine maintenance activity; and land disturbing activities.

“Regulatory agencies” means appropriate departments of a governmental body with permitting or decision-making authority relative to an action.

“Replaced hard surface” means, for structures, the removal and replacement of impervious surfaces down to the foundation. For other hard surfaces, the removal down to bare soil or base course and replacement.

“Rough grading” means clearing, grading and construction stormwater management activities to achieve project boundaries and approximate earthen grades in accordance with an approved plan that are permitted for construction prior to issuance of all final site work, building, and other permits required for a proposed project. Also includes associated activities that are required prior to rough grading such as demolition and preloading.

“Runoff” means water originating from rainfall and other precipitation that is found in drainage facilities, rivers, streams, springs, seeps, ponds, lakes and wetlands as well as shallow groundwater as well as on ground surfaces. For the purposes of this definition, “groundwater” means all waters that exist beneath the land surface or beneath the bed of any stream, lake or reservoir, or other body of surface water, whatever may be the geological formation or structure in which such water stands or flows, percolates, or otherwise moves.

“Site” means that defined portion of any lot(s) or parcel(s) of land or contiguous combination thereof subject to new development or redevelopment. For road projects, the length of project site and right-of-way boundaries define the site.

“Slide” means the movement of a mass of loosened rocks or earth down a hillside or slope.

“Slope” means an inclined ground surface, the inclination of which is expressed as a ratio of horizontal distance to vertical distance or as an angle from the horizontal.

“Source control BMP” means a structure or operation that is intended to prevent pollutants from coming into contact with stormwater through physical separation of areas or careful management of activities that are sources of pollutants. The Ecology Stormwater Management Manual for Western Washington separates source control BMPs into 2 types. Structural source control BMPs are physical, structural, or mechanical devices, or facilities that are intended to prevent pollutants from entering stormwater. Operational BMPs are nonstructural practices that prevent or reduce pollutants from entering stormwater.

“Stormwater” means runoff during and following precipitation and snowmelt events, including surface runoff, drainage or interflow.

“Stormwater design manual” means the Department of Ecology 2019 Stormwater Management Manual for Western Washington, prepared by the Department of Ecology, as supplemented and modified by the City of Issaquah 2022 Addendum to the Department of Ecology 2019 Stormwater Management Manual for Western Washington that specifies local requirements and procedures, describing surface and stormwater design and analysis requirements, procedures and guidance.

“Stormwater facility” means a constructed component of a stormwater drainage system, designed or constructed to perform a particular function, or multiple functions. When used singly or in combination, stormwater facilities reduce the potential for contamination of surface and/or groundwaters. Stormwater facilities include, but are not limited to, pipes, swales, ditches, culverts, street gutters, detention ponds, retention ponds, constructed wetlands, infiltration devices, catch basins, oil water separators, and biofiltration swales.

“Stormwater treatment and flow control BMPs/facilities” means detention facilities, permanent treatment BMPs/facilities; and bioretention facilities, vegetated roofs, and permeable pavements that help meet Minimum Requirements No. 6 (treatment), No. 7 (flow control), or both of the 2019-2024 Western Washington Phase II Municipal Stormwater Permit Appendix 1.

“Stream” means an area in the City of Issaquah where water conveyed on the surface produces a defined channel or bed. A defined channel or bed is an area which demonstrates clear evidence of the passage of water and includes, but is not limited to, bedrock channels, gravel beds, sand and silt beds and defined-channel swales. The channel or bed need not contain water year-round. This definition is not meant to include entirely artificially constructed watercourses, including irrigation ditches, roadside ditches, canals, storm or surface water runoff conveyance devices or other artificial watercourses unless they have documented fish use and have a free and open surface connection to waters of the State or are used to convey water naturally occurring prior to construction. Also see definition of “Ditch.” (Ord. 3023 §§ 19, 20, 2023; Ord. 2989 § 2 (Exh. A2), 2022; Ord. 2783 § 3 (Exh. A3), 2016; Ord. 2560 § 3 (Exh. A2), 2009; Ord. 2487 § 1, 2007).