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Illegal Discharge.
Any direct or indirect non-storm water discharge to MS4.
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Illicit Connection(s).
Any man-made conveyance that is connected to the MS4 in violation of chapter 17D.060 SMC.
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Illicit Discharge.
This term is covered in SMC 17D.060.190.
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Illuminated Wall Highlights.
Lighted areas that highlight a building’s architectural or structural features and that do not convey a message or image. Illuminated wall highlights can either be created by light projected onto a feature or highlighting a feature with neon tubing or other light fixture.
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Impact Fee.
A charge or fee assessed by the City which mitigates all or any portion of a direct impact.
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Impermeable Sediment.
Sediment restricting the flow of water.
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Impervious Surface
Ground surfaces and coverings composed of water-impenetrable materials such as asphalt, concrete, brick, stone and rooftops.
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Improvements.
Improvements require under conditions of approval such as streets, drainage facilities, and utilities.
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Incentives.
Such rights or privileges as may from time to time exist to compensate the owner for the imposition of controls on a designated district or landmark.
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In-ground Storage Tank (IST).
Any one or a connected combination of tanks that is used to contain an accumulation of liquid critical materials, the aggregate of which (including the volume of piping connected thereto) is more than sixty gallons that is situated to any degree within the ground, and the entire exterior surface of the tank cannot be fully visually inspected. The surface area of tank located above the ground will be treated as an aboveground storage tank (AST), and the area below the ground will be treated as an underground storage tank (UST).
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In-kind Compensation.
The restoration or replacement of a wetland with hydrogeomorphic characteristics closely approximating those of a specified wetland.
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Inner Gorge Slope.
Canyon walls created by a combination of stream downcutting/undercutting and mass wasting on the slope walls. Inner gorges may show evidence of recent movement, such as landslides, surface erosion, vertical tracks of disturbance vegetation, or areas that are concave in contour and/or profile. The steepness of inner gorges varies with the underlying materials. Slope gradients as gentle as about twenty-eight degrees (fifty-three percent) can be unstable in gorges, cut into incompetent bedrock, weathered materials or unconsolidated deposits. A minimum vertical height of ten feet is usually applied to distinguish between inner gorges and slightly incised streams. The top edge of an inner gorge is typically distinguished by a distinct break in slope. The upper boundary of an inner gorge is assumed to be a line along the first break in slope of at least ten degrees (seventeen percent).
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In-stream Structure.
A structure placed by humans within a stream or river waterward of the ordinary high-water mark that either causes or has the potential to cause water impoundment or the diversion, obstruction, or modification of water flow. In-stream structures may include those for hydroelectric generation, irrigation, water supply, flood control, transportation, utility service transmission, fish habitat enhancement, or other purpose.
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Infiltration.
The downward entry of water into the immediate surface of soil.
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Integral Curb and Gutter.
Concrete curb and gutter which is formed and placed as one unit.
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“Interior Noise Level” means the average level of sound expressed in decibels (dB) measured in any habitable room with exterior windows and doors closed.
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Interpretive Signs.
See SMC 17C.240.015
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Interstitial Monitoring.
A method of leak detection based on determining if there has been a failure of one of the containment layers surrounding an interstitial space. Monitoring methods may include the:
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detection of pressure changes within the space;
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detection of vapors from the contained material within the space; or
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physical detection of contained material, or water from outside the container, within the space.
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Interstitial Space.
The volume between two separate layers of a secondary or multiple containment system. The space may be filled with air or other gas or it may be filled with a porous material.
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Invasive Species.
A species that is:
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non-native (or alien) to city of Spokane; and
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whose introduction causes or is likely to cause economic or environmental harm, or harm to human health.
