Alaska Admin. Code tit. 18, § 74.120 – Classification of water and wastewater systems

(a) Water distribution and wastewater collection systems designated in 18 AAC 74.006 are classified as follows:
1. (1) except as provided in (2) and (3) of this subsection, water distribution and wastewater collection systems are classified as follows:
  1. (A) systems with 15 to 500 service connections are classified as class 1;
  2. (B) systems with 501 to 5,000 service connections are classified as class 2;
  3. (C) systems with 5,001 to 15,000 service connections are classified as classified as class 3;
  4. (D) systems with more than 15,000 service connections are classified as class 4;
2. (2) for water distribution systems, the following requirements also apply:
  1. (A) water distribution systems where water is circulated or heated to prevent freezing in the water distribution system will be classified at one class higher than the class determined under (1)(A) - (C) of this subsection;
  2. (B) water distribution systems with five or more pressure zones will be classified at one class higher than the class determined under (1)(A) - (C) of this subsection;
  3. (C) water distribution systems with five or more pressure zones and where water is circulated or heated to prevent freezing in the water distribution system will be classified at one class higher than the class determined under (1)(A) - (C) of this subsection;
3. (3) for wastewater collection systems, the following requirements also apply:
  1. (A) wastewater collection systems where gravity is the only means of wastewater flow will be classified as class 1 systems, regardless of the number of service connections;
  2. (B) wastewater collection systems with 15 or more main line lift stations will be classified at one class higher than the class determined under (1)(A) - (C) of this subsection.
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(b) Water treatment and wastewater treatment systems designated in 18 AAC 74.006 are classified as follows:
1. (1) wastewater treatment systems that score 1 - 30 points under (d) of this section, and where stabilization ponds without aeration are the only means of secondary treatment, are classified as wastewater stabilization pond systems;
2. (2) water treatment and wastewater treatment systems, other than wastewater stabilization pond systems, are classified as set out in Table B of this subsection.
(By Range of Points)
TABLE B CLASSIFICATION RATING SYSTEM: TREATMENT SYSTEMS (By Range of Points) System Type 1 2 3 4 Wastewater Treatment System1-3031-5556-7576 and aboveWater Treatment System1-3031-5556-7576 and above
(c) The department may, after considering advice of the board, modify the rating system in (a) and (b) of this section as applied to a particular system if the department finds that
1. (1) unusual factors affect the complexity of unit processes, the quality of raw water sources, or the users of water downstream from wastewater system discharges; or
2. (2) potential health hazards exist.
(d) To classify wastewater treatment systems under (b) of this section,
1. (1) the department will use the following point system:
2. (2) for purposes of this subsection, community septic tanks will be considered part of the wastewater collection system, not a primary treatment method; and
3. (3) nutrient removal utilizing biological or combined chemical and biological processes for advanced waste treatment include one or more of the following methods:
  1. (A) nitrification that utilizes those processes, if a facility nitrifies based solely on detention time or another extended aeration process, only the points for nitrification by extended aeration will be given;
  2. (B) denitrification;
  3. (C) phosphorous removal.
Item Points Size Peak day design capacity, gallons per day:less than 10,000 . . . . . 110,000 - 50,000 . . . . . 250,001 - 100,000 . . . . . 4100,001 - 500,000 . . . . . 9500,001 - 1,000,000 . . . . . 121,000,001 - 5,000,000 . . . . . 165,000,001 - 10,000,000 . . . . . 2010,000,001 - 50,000,000 . . . . . 25greater than 50,000,000 . . . . . 30Pretreatment Influent pumping . . . . . 2Flow equalization basin . . . . . 1Manually cleaned screens . . . . . 1Mechanically cleaned screens . . . . . 2Fine screens, including microscreens . . . . . 3Comminutor, barminutor, grinders . . . . . 2Grit removal . . . . . 2Primary treatment Primary clarifiers . . . . . 4Primary clarifiers with chemical addition . . . . . 7Imhoff tank, or other method of combined sedimentation and digestion, other than a septic tank . . . . . 3Dissolved air flotation . . . . . 16Secondary Treatment Trickling filter without recirculation . . . . . 5Trickling filter with recirculation . . . . . 8Activated sludge: . . . . . Oxidation ditch . . . . . 8Diffused or dispersed aeration . . . . . 10Pure oxygen . . . . . 15Sequencing batch reactor (SBR), intermittent cycle extended aeration system (ICEAS), or other batch treatment method . . . . . 20Additional points if an activated sludge plant is operated in high rate mode or contact stabilization mode . . . . . 2Rotating biological contactor . . . . . 10Activated bio-filter with aeration . . . . . 10Activated bio-filter without aeration . . . . . 8Stabilization ponds without aeration . . . . . 5Aerated lagoon . . . . . 8Secondary clarifiers . . . . . 4Secondary clarifiers with chemical addition . . . . . 7Advanced Waste Treatment Polishing pond or effluent flow equalization . . . . . 2Chemical and physical treatment without secondary treatment . . . . . 20Chemical and physical treatment following secondary treatment . . . . . 15Ion exchange . . . . . 4Granular media filtration . . . . . 8Membrane filtration, including reverse osmosis, microfiltration, ultrafiltration or nanofiltration . . . . . 8Membrane filtration, integrated system . . . . . 12Electrodialysis, electrodialysis reversal . . . . . 10Biological or combined chemical and biological nutrient removal . . . . . 12Nitrification by extended aeration only . . . . . 2Chemical precipitation of phosphorous . . . . . 3pH adjustment . . . . . 3Activated carbon columns or beds . . . . . 8In-Plant Odor Control (maximum of 6 points in any combination) Biofilter . . . . . 3Adsorption with activated carbon or equal adsorbent . . . . . 3Wet scrubber . . . . . 3Thermal deactivation with catalytic process . . . . . 6Odor-reducing sprays . . . . . 2Sludge Thickening and Dewatering Sludge decant tank . . . . . 2Gravity thickener basin . . . . . 3Gravity belt thickener . . . . . 4Screw press . . . . . 5Centrifuge . . . . . 6Belt filter press, plate-and-frame press, or vacuum filter . . . . . 8Sludge bagger . . . . . 3Evaporative sludge drying by means of drying beds . . . . . 23 Sludge Stabilization and Conditioning Unheated anaerobic digestion . . . . . 8Heated anaerobic digestion . . . . . 10Aerobic digestion . . . . . 5Wet oxidation . . . . . 10Chemical stabilization with lime . . . . . 3In-vessel composting, if controlled and operated by the operator as part of routine system operations . . . . . 10Static pile composting, if controlled and operated by the operator as part of routine system operations . . . . . 5Solids Disposal Incineration, if controlled and operated by the operator as part of routine system operations . . . . . 12Land application, if controlled and operated by the operator as part of routine system operations . . . . . 5Sludge lagoon . . . . . 3Off-site disposal . . . . . 1Disinfection Liquid and powdered hypochlorites . . . . . 3Additional points if hypochlorites are generated on-site . . . . . 2Gas chlorine . . . . . 12Chlor-alkali on-site generation . . . . . 12Chlorination using tablets . . . . . 1Ultraviolet light . . . . . 3Ozonation without pure oxygen . . . . . 3Ozonation with pure liquefied oxygen . . . . . 4Ozonation with on-site generation of pure oxygen . . . . . 5Dechlorination with gas . . . . . 10Dechlorination with chemical dechlorination agents other than gas . . . . . 3Dechlorination using tablets . . . . . 1Effluent Discharge Plant pumping of effluent . . . . . 2Effluent aeration . . . . . 2
(e) To classify water treatment systems under (b) of this section,
1. (1) the department will use the following point system:
2. (2) for purposes of the point system set out in (1) of this subsection, the department will assign a point value to ozonation only once, even if ozonation is used to accomplish multiple water treatment objectives;
3. (3) for purposes of the point system set out in (1) of this subsection, a system with a water storage tank for the purpose of achieving contact time and with a water storage tank for the purpose of storing finished water will only be assigned a point value for the water storage tank used for the purpose of achieving contact time.
Item Points Size Peak day design capacity, gallons per day less than 10,000 . . . . . 110,000 - 50,000 . . . . . 250,001 - 100,000 . . . . . 4100,001 - 500,000 . . . . . 9500,001 - 1,000,000 . . . . . 121,000,001 - 5,000,000 . . . . . 165,000,001 - 10,000,000 . . . . . 2010,000,001 - 50,000,000 . . . . . 25greater than 50,000,000 . . . . . 30Water Supply Source Groundwater . . . . . 2Groundwater under the direct influence of surface water . . . . . 4Surface water . . . . . 6Surface water maintaining filtration avoidance criteria under 18 AAC 80.620 . . . . . 8Seawater . . . . . 10Purchased treated water . . . . . 0Raw water storage tank . . . . . 3Pretreatment Presedimentation basin . . . . . 4Hydrocyclone or similar sand separator device . . . . . 2Microscreen . . . . . 3Roughing filter: . . . . . Cartridge filter . . . . . 2Non-backwashable strainer or filter . . . . . 2Gravel or rock filter . . . . . 4Backwashable granular media filter . . . . . 8Add-heat system to heat raw water . . . . . 2Adjustment and Corrosion Control pH adjustment . . . . . 3Corrosion inhibitor . . . . . 3Limestone or calcite contractor . . . . . 2Sequestration . . . . . 3Treatments Aeration:In-line venturi-type . . . . . 1Mechanical or diffused . . . . . 3Degasification . . . . . 3Ion exchange . . . . . 4Non-regenerated sorption processes, including activated alumina, modified activated alumina, and iron-based sorbents . . . . . 3On-site regeneration of sorption process media . . . . . 10Activated carbon, if not included as a bed layer in another filter: . . . . . Activated carbon cartridge or bag filter . . . . . 2Powdered activated carbon treatment . . . . . 4Granular activated carbon contactors . . . . . 4On-site regeneration of activated carbon . . . . . 16Chemical oxidation: Hypochlorite solution . . . . . 3Gas chlorine . . . . . 12Potassium permanganate . . . . . 4Hydrogen peroxide . . . . . 5Ozonation without pure oxygen . . . . . 3Ozonation with pure liquefied oxygen . . . . . 4Ozonation with on-site generation of pure oxygen . . . . . 5Coagulation:Primary coagulant . . . . . 5Coagulant aid, flocculent, or filter aid . . . . . 3 points for each chemical added, up to a maximum of 12 pointsRapid mix units:Mechanical mixers . . . . . 5Injection mixers . . . . . 3In-line blender mixers . . . . . 2In-line static mixers . . . . . 0Flocculation tanks:Hydraulic flocculator . . . . . 4Mechanical flocculator . . . . . 8Sedimentation or clarification:Tube settlers . . . . . 2Inclined-plate, Lamella-type or equivalent . . . . . 2Horizontal flow conventional clarifier . . . . . 4Batch sedimentation . . . . . 2Adsorption clarifier . . . . . 6Up-flow solids contact . . . . . 10Dissolved air flotation . . . . . 16Combined rapid mix-coagulation-flocculation-sedimentation unit . . . . . 20Filtration:Cartridge or bag filter - single unit . . . . . 2Cartridge or bag filters - staged, multiple units . . . . . 4Slow sand . . . . . 4Granular media . . . . . 8Membrane filtration, including reverse osmosis, microfiltration, ultrafiltration, or nanofiltration . . . . . 8Membrane filtration, integrated system . . . . . 12Diatomaceous earth . . . . . 12Electrodialysis, electrodialysis reversal, distillation . . . . . 10Lime softening . . . . . 16Recarbonation . . . . . 8Fluoridation:Sodium fluoride saturator . . . . . 2Sodium silicofluoride . . . . . 3Hydrofluorosilicic acid . . . . . 5Disinfection:Liquid and powdered hypochlorites . . . . . 3Additional points if hypochlorites are generated on-site . . . . . 2Gas chlorine . . . . . 12Chlorination using tablets . . . . . 1Ammonia addition for chloramination:using liquid ammonia solution . . . . . 3using ammonia gas . . . . . 12Chlorine dioxide . . . . . 8Chlor-alkali on-site generation . . . . . 12Ozonation without pure oxygen . . . . . 3Ozonation with pure liquefied oxygen . . . . . 4Ozonation with on-site generation of pure oxygen . . . . . 5Ultraviolet light . . . . . 2Ultraviolet light, for the purposes of meeting required inactivation . . . . . 4Water storage tank, for the purpose of achieving contact time . . . . . 3Finished water storage tank, if the system serves fewer than 500 individuals or 100 service connections, andthe tank has a capacity of 1,000,000 gallons or more . . . . . 3the tank has a capacity of 50,000 - 999,999 gallons . . . . . 2Pressure tanks . . . . . 0On-site treatment of system sludge or backwash:Discharge to sewer or other off-site treatment . . . . . 0Discharge to on-site pond, septic tank, or lagoon . . . . . 2Mechanical dewatering . . . . . 6Filter backwash water or sludge supernatant recycling:groundwater source . . . . . 2surface water source . . . . . 3

(Eff. 8/21/78, Register 67; am 8/24/85, Register 95; am 1/18/2001, Register 157; am 12/3/2006, Register 180; am 11/21/2010, Register 196; am 11/26/2016, Register 220)

Authority: AS 46.30.010, AS 46.30.080, AS 46.30.090