Terms as defined in this section are applied throughout this chapter.

(1) "Air gap" means an unobstructed physical separation between the free-flowing discharge end of a supply pipe and the overflow rim of an open or nonpressurized receiving vessel. The separation must be at least four times the diameter of the supply pipe measured vertically from the overflow rim of the receiving vessel, and in no case be less than 25 mm, or one inch.

(2) "Alternative technology" means any device or concept that meets the performance standards contained in this chapter.

(3) "Antipollution safety device" means any equipment or device effectively designed, constructed, and maintained that is used in the event of malfunction or shutdown to prevent backflow of a chemical or treated water into the water supply, or to reduce human exposure or hazard to the environment. Equipment or devices may include, but are not limited to, the irrigation line check valve, vacuum relief valve, low-pressure drain, inspection port, metering device, chemical injection closure device, and system interlock.

(4) "Application depth" means the amount of irrigation water applied to a given unit area during an irrigation set, and is usually expressed in inches or gallons.

(5) "Application season" means the period during which product is injected into an irrigation system for crop protection, plant growth, or soil preparation.

(6) "Application tank" means a product container and appurtenances used for the storage of product that is dedicated for use with and functionally connected to an irrigation system.

(7) "Applicator" or "operator" means any individual who has assumed responsibility or is considered principally responsible to ensure that the fertigation system functions properly and conforms with the provisions of this chapter.

(8) "Approved backflow prevention assembly" means a reduced pressure backflow assembly, reduced pressure detector assembly, double check valve detector assembly, or double check valve assembly of a make, model, and size that is approved by the department of health pursuant to WAC 246-290-490.

(9) "Approved reduced pressure backflow assembly" or "reduced pressure detector assembly" means backflow prevention assemblies of make, model, and size approved by the department of health pursuant to WAC 246-290-490.

(10) "Aquaculture" means the cultivation of water-based plants or animals.

(11) "Backflow" means the reversal of fluid flow due to backpressure or backsiphonage.

(12) "Backflow prevention device" or "backflow safety device" means antipollution safety devices that prevent the flow of water from the irrigation water distribution system back to the water source or to the product source.

(13) "Barometric loop" or "gooseneck" means a raised section of pipe where the bottom of the loop is at least two feet above the highest water emitting device or any portion of the irrigation application system which has a vacuum relief valve installed on the top of the loop.

(14) "Check valve" means a certified device designed and constructed to provide automatic, quick-acting, and absolute closure that creates and maintains a watertight seal. The device prevents flow in the opposite direction of that desired when operation of the irrigation system or chemical injection unit fails or is shut down.

(15) "Chemical" or "product" means a commercial fertilizer, soil amendment, system maintenance compound, or other materials such as reclaimed water or animal effluent.

(16) "Commercial fertilizer" means a substance containing one or more recognized plant nutrients and which is used for its plant nutrient content and/or which is designated for use or claimed to have value in promoting plant growth, and shall include limes, gypsum, and manipulated animal and vegetable manures. It shall not include unmanipulated animal and vegetable manures and other products exempted by the department by rule.

(17) "Contact name" means a person or company responsible for placement and operation of an application tank.

(18) "Decommissioned" means rendering an application tank unusable for product containment.

(19) "Deep percolation" means the movement of water downward through the soil profile below a plant's effective rooting zone.

(20) "Department" means the Washington state department of agriculture.

(21) "End gun" means an intermittent, high volume water-emitting device located at or near the end of an irrigation application system.

(22) "Environment" means any plant, animal, natural resource, surface water (including underlying sediments), groundwater, drinking water supply, land surface or subsurface strata, or ambient air within the state of Washington or under the jurisdiction of the state of Washington.

(23) "Fertigation" means the application of any commercial fertilizer, nutrient, soil amendment, or reclaimed water with irrigation water intended for plant or soil biota growth and development or for soil conditioning or reclamation.

(24) "Fertigation operation" means all activities and equipment associated in preparing for, performing, and concluding a fertigation application, which includes, but is not limited to, calibrating, mixing, loading, starting up, operating, monitoring, or shutting down a fertigation system.

(25) "Fertigation system" means the chemical injection system as well as the irrigation water distribution system.

(26) "Homemade" means devices not otherwise commercially available for sale or not manufactured for the purpose of commercial sale.

(27) "Hydroponic" means the practice of growing plants in an aqueous solution, moist inert material, or otherwise in the absence of a mineral-based medium.

(28) "Imminent danger" means a threat to human health or the environment that is likely to happen during the current application.

(29) "Injection system" means all components used to supply, deliver, meter, and inject a substance into an irrigation system. This includes devices and components located between and inclusive of the application tank and the point of product discharge into the irrigation water, including components of the system interlock.

(30) "Inspection port" means an orifice or other viewing device from which the low pressure drain and irrigation line check valve may be assessed for proper operation.

(31) "Irrigation application system" means the physical components of an irrigation system that begins at the first water emitting device and ends with the last water emitting or purging device.

(32) "Irrigation season" means that period of time during which supplemental water is applied to aid in plant development, soil conditioning, temperature modification, or other such purposes.

(33) "Irrigation system" means all components used in diverting, supplying, distributing, and applying irrigation water.

(34) "Irrigation water distribution system" means all components inclusive of the irrigation water supply system and the irrigation application system.

(35) "Irrigation water supply system" means the water conveyance system, which begins at the point of diversion from the irrigation water source and ends with the first water emitting device.

(36) "Metering device" means a positive displacement injection pump, venturi device, or gravity feed device capable of being calibrated and used to gauge chemical placement into the irrigation water distribution system.

(37) "Nonpressurized water delivery system" means a method of irrigation in which water is distributed over the soil surface by gravity flow, such as rill, border, gated pipe, or spigotted pipe.

(38) "Offsite application" means the application or movement of product from the target site.

(39) "Operator" means the individual who is performing a fertigation operation.

(40) "Outtake" means an opening that provides a source of untreated water.

(41) "Reclaimed water" means process water discharge from food processors and from wastewater treatment facilities, which is applied to land or plants with the intention of recovering water and nutrients.

(42) "Rinsate" means the liquid produced from the rinsing of any equipment or container that has come in direct contact with any fertilizer or soil amendment.

(43) "Runoff" means surface water leaving the target site.

(44) "Sensitive area(s)" means schools, parks, dwellings, occupied buildings or structures, public roadways, waters of the state, or other areas in which off-target movement may endanger humans, animals, crops, or the environment.

(45) "Soil amendment" means any organic or inorganic substance, other than a commercial fertilizer as defined in WAC 16-200-695, that is intended to improve the physical characteristics of the soil or to make the growth medium more suitable for the establishment, growth, and production of plants.

(46) "Source water" or "water source" means an aquifer or surface water body, including a stream, stream system, lake, reservoir, or off-farm irrigation water ditch or conveyance system, and any spring water or underground water that is part of or tributary to the surface water body or aquifer.

(47) "System interlock" means the arrangement or interconnection of the irrigation pump or a pressure or flow sensing device with the chemical injection unit or other pumps in such a manner that shutdown of the fertigation injection system will occur in the event of any component malfunction or failure that substantially impacts the application rate.

(48) "Vacuum relief valve" means a device that automatically relieves or breaks a vacuum, thereby preventing backsiphoning.

(49) "Washwater" means the liquid produced from the rinsing of the exterior of any equipment or containers that have or may have come in direct contact with any fertilizer or soil amendment.

(50) "Waters of the state" means, but is not limited to, lakes, rivers, ponds, streams, inland waters, underground waters, salt waters, irrigation canals, and reservoirs.