The definitions in this section apply throughout this chapter unless the context clearly requires otherwise.
“Approve” or “approval”means the decision or determination of the director that an action conforms to this chapter.
“As-built”means a final drawing of the actual installation of structures, materials and equipment.
“Basin plan”means a plan and all implementing regulations and procedures adopted by the city for managing surface and stormwater quality and quantity, stormwater facilities, and features within an individual hydrologic area.
“Best management practices (BMP)”means schedules of activities, prohibitions of practices, maintenance procedures, and structural and/or managerial practices that, when used singly or in combination, prevent or reduce the release of pollutants and other adverse impacts to waters of Washington State.
“City”means the city of Mill Creek.
“Civil engineer”means a professional engineer licensed in the state of Washington in civil engineering.
“Clearing”means destruction, deformation or removal of vegetation by manual, mechanical, or chemical methods or means.
“Compaction”means the densification of a fill or naturally existing soils by mechanical means.
“Current conditions”means the state, status, or condition of property at the time application is made for a project (or portion thereof) subject to this chapter. Current conditions may include but are not limited to buildings, impervious areas, and topography; provided, that such conditions are naturally occurring, or were legally created or lawfully conformed to the requirements of the city or other permitting authority at the time they were established. The advocate for a current condition has the burden of proving the conforming nature of the condition.
“Detention”means the temporary storage of surface water in a stormwater facility before release to the stormwater system at a rate slower than that at which it is collected.
“Detention facility”means an above or below ground stormwater facility, such as a pond or vault, that temporarily stores surface water and subsequently releases it at a slower rate than it is collected by the stormwater system.
“Developed conditions”means the state, status, or condition of property at the time a proposed project has been completed. Developed conditions may include but are not limited to buildings, impervious areas, and topography.
“Director”means the director of the Mill Creek public works department, or his/her designated representative, or other person designated by the city manager.
“Drainage system”means the system comprised of all natural and artificial elements that collects, conveys, contains, and discharges surface and stormwater within, through or outside the city. The drainage system includes the stormwater system in the city and all receiving or discharging waters or channels outside the city (e.g., North Creek, Nickel Creek, Penny Creek, etc.).
“Emergency”means any natural or humancaused event or set of circumstances that disrupts or threatens to disrupt, or endangers or threatens to endanger, the operation, structural integrity or safety of the stormwater system, or endangers or threatens to endanger the health and safety of the public, or otherwise requires immediate action by the utility.
“Engineering standards”means the engineering standards adopted by the director, if any, whether in draft or final form, which include minimum requirements for the design and construction of water, stormwater, and/or sanitary sewer facilities.
“Erosion”means the wearing away, detachment or movement of soil or the land surface by running water, wind, ice, gravity or other geological agents, including without limitation such processes as gravitational creep.
“Excavation”means the removal or movement of earth material.
“Fill”means a deposit of earth material placed by artificial means.
“Forest practice”means any activity conducted on or directly pertaining to forest land and relating to growing, harvesting or processing timber, including but not limited to road and trail construction; harvesting, final and intermediate; pre-commercial thinning; reforestation; fertilization; prevention and suppression of diseases and insects; salvage of trees and brush control.
“Groundwater”means water in a saturated zone or stratum beneath the surface of land or a water body.
“Illicit discharge”means any discharge or connection to the stormwater system that causes or contributes to a violation, impairment or degradation of water quality, sediment quality, habitat quality, groundwater quality, or violation of this chapter, including but not limited to sanitary sewer discharges, industrial process water, interior floor drains, car wash and rinse water, and gray water discharges.
“Impervious surface”means any hard surface area which either prevents, impedes or retards the entry of water into the soil mantle under natural conditions prior to development, and/or a hard surface area which causes water to run off of the surface at 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 rooftops, concrete or asphalt paving, graveled areas, walkways, patios, driveways, parking lots, storage areas, and oiled, macadam, or other similar surfaces. Open, uncovered detention/retention facilities do not constitute impervious surfaces.
“Infiltration”means the downward movement of water from the surface to the subsoil.
“Infiltration facility”means a stormwater facility designed to use the hydrologic process of surface and stormwater runoff soaking into the ground, commonly referred to as percolation, to dispose of surface and stormwater runoff.
“Interflow”means that portion of precipitation that infiltrates into the soil and moves laterally through the upper soil horizons until intercepted by a stream channel or until it returns to the surface via a wetland, spring, or seep.
“Land disturbing activity”means any activity that results in a change in the existing soil cover (both vegetative and nonvegetative) and/or the existing soil topography. Land disturbing activities include but are not limited to demolition, construction, clearing, grading, filling and excavation.
“Latecomer agreement”means a contract which provides for the reimbursement of persons who construct a public stormwater facility or system extension.
“LID”means local improvement district; or “low impact development (LID)” means a stormwater management strategy that emphasizes conservation and use of existing site features integrated with distributed, small-scale stormwater controls to more closely mimic natural hydrologic patterns in residential, commercial, and industrial settings.
“Maintenance standards”means utility maintenance standards, if any, which may include but are not limited to minimum requirements for maintaining stormwater facilities so they function as intended.
“Mitigate” or “mitigation”means, in order of preference:
1. Avoiding the impact altogether, which may include not taking or modifying a certain action or part of an action.
2. Minimizing impacts, which may include limiting the degree or magnitude of the action and its implementation, by using appropriate technology, or by taking affirmative steps to avoid or reduce impacts.
3. Rectifying the impact, which may include repairing, rehabilitating or restoring the affected environment.
4. Reducing or eliminating the impact over time, which may include preservation and maintenance operations during the life of the action.
5. Compensating for the impact, which may include replacing, enhancing, or providing substitute resources or environments.
“New development”means any human-caused or artificial change to property or structures including but not limited to land disturbing activities, including mining, dredging, filling, clearing, grading, landscaping, paving, excavating, or drilling; structural development, including construction, installation or expansion of a building or other structure; creation of impervious surfaces; and subdivision, short subdivision, or binding site plan as defined in MCMC Titles 14 through 18. “New development” does not include any other forest practices or commercial agriculture or the cleaning or other maintenance of a detention facility.
“Operate,”for purposes of the public stormwater system, means to manage on a full-time basis a stormwater facility or the flow of water through any portion of the stormwater system.
“Permanent stormwater quality control plan (PSQCP)”means a plan prepared in accordance with the Ecology Manual which includes permanent BMPs for the control of pollution from stormwater after construction and/or land disturbing activity has been completed. For small sites, this requirement is met by implementing a small parcel erosion and sediment control plan (SPESCP).
“Person”means any individual, partnership, corporation, limited liability company, joint venture, association, organization, society, cooperative, public or municipal corporation, or agency of the state or local government unit, however formed or designated.
“Pollutant”means any substance that, when added to water, would contaminate or alter the chemical, physical, or biological properties of any waters of the city’s stormwater system or waters of the state.
“Pollution”means contamination, pollution, or other alteration of the physical, chemical, or biological properties of the stormwater system or waters of the state (as defined in RCW
90.48.020), including without limitation change in temperature, taste, color, turbidity, or odor of the water, or the discharge of any liquid, gaseous, solid, radioactive or other substance into any waters of the state as will or is likely to create a nuisance or render such waters harmful, detrimental or injurious to the public health, safety, or welfare, or to domestic, commercial, industrial, agricultural, recreational, or other legitimate beneficial uses, or to livestock, wild animals, birds, fish or other aquatic life.
“Private stormwater facility”means any stormwater facility or portion of the stormwater system which is not a public stormwater facility or public stormwater system.
“Program”means the surface water management program described in this chapter.
“Property owner”means any person that owns or has a legal interest in property or has been authorized by such person to act on its behalf.
“Public stormwater system”means those elements of the stormwater system which are operated by the utility, and are either (1) located on property owned by the city or in a public right-of-way, or (2) if located on private property, the city has formally accepted and documented by deed, easement or similar instrument the obligation to operate that portion of the stormwater system.
“Redevelopment”means, on an already developed site, the creation or addition of impervious surfaces; the expansion of a building footprint or addition or replacement of a structure; structural development, including but not limited to construction, installation, or expansion of a building or other structure and/or replacement of impervious surface that is not part of a routine maintenance activity; land disturbing activities associated with structural or impervious surface development; and any change in use that has the potential of releasing pollutants from the site.
“Retain” or “retention”means the storage of stormwater for a considerable length of time with no surface outflow (i.e., release occurs only through evaporation, plant transpiration, or infiltration).
“Retention facility”means a stormwater facility, such as a pond or vault, that is intended to retain stormwater.
“Site”means a portion of any property that is directly subject to development or is within the boundaries of a project.
“Soil”means unconsolidated mineral and organic material on the immediate surface of the earth that serves as a natural medium for the growth of land plants.
“Soil management plan, (SMP)”means a plan of best management practices for improving soil quality for new development in order to protect and restore soil function.
“Source control BMPs”means BMPs that are intended to prevent pollutants from entering stormwater. Examples include erosion control practices, maintenance of stormwater facilities, providing roofs for storage and working areas, and directing wash water and similar discharges to the sanitary sewer or a dead-end sump.
“Stormwater”means that portion of precipitation or surface water flow that does not naturally percolate into the ground or evaporate. By way of example only, stormwater may flow overland, or through interflow, or through channels, streams, pipes, ditches, infiltration facilities, or other conveyances or routes. “Stormwater” includes surface water.
“Stormwater connection permit”means the permit required to construct stormwater facilities and/or to make any additions, repairs, or connections to the stormwater system.
“Stormwater facility”means a constructed component or segment of the stormwater system. Stormwater facilities include, but are not limited to, pipes, swales, ditches, culverts, street gutters, detention/retention/infiltration facilities, constructed wetlands, LID features, catch basins, oil/water separators, sediment basins, modular pavement, constructed ponds and streams, or any other constructed conveyance of or for stormwater.
“Stormwater site plan”means a comprehensive report containing all of the technical information and analysis necessary for regulatory agencies to evaluate a proposed new development or redevelopment project for compliance with stormwater requirements. Contents of a stormwater site plan will vary with the type and size of the project, and individual site characteristics.
“Stormwater system”means the entire system within the city, both public and private, whether naturally existing or manmade, which is designed for, intended for, or which handles the collection, drainage, conveyance, diversion, abatement, detention, retention, infiltration, treatment, storage, LID features or disposition of stormwater. By way of example only, the stormwater system may include pipes, culverts, ditches, open channels, streams, lakes, rivers, ponds, and stormwater facilities. The stormwater system is a subset of the drainage system.
“Stormwater treatment BMPs”means BMPs that remove pollutants from stormwater using gravity, settling, filtration, biological uptake, and soil adsorption.
“Stream”means any and all surface water routes generally consisting of a channel having a bed, banks, and/or sides in which surface waters flow in draining from higher to lower land, both perennial and intermittent; and including intervening artificial components.
“Utility”means the surface water utility of the city established under Chapter
8.12 MCMC.
“Vegetation”means all organic plant life growing on the surface of the earth.
“Water body”means surface waters of the state, including but not limited to rivers, streams, lakes, marine waters, estuaries and wetlands.
(Ord. 2000-498 § 2; Ord. 2005-609 § 2; Ord. 2009-702 § 2 (Exh. C); Ord. 2017-814 § 2; Ord. 2024-921 § 1 (Exh. A))