OAR 340-049-0025
Criteria for Classifying Wastewater Treatment Systems

(1)

Design Population or Population Equivalent Points:

(a)

Less than 750 — 0.5 points;

(b)

751 to 2000 — 1 point;

(c)

2001 to 5000 — 1.5 points;

(d)

5001 to 10,000 — 2 points;

(e)

Greater than 10,000 — 3 points plus 1 point per 10,000.

(2)

ADWF Points:

(a)

Less than 0.075 MGD — 0.5 point;

(b)

Greater than 0.075 to 0.1 MGD — 1 point;

(c)

Greater than 0.1 to 0.5 MGD — 1.5 points;

(d)

Greater than 0.5 to 1.0 MGD — 2 points;

(e)

Greater than 1.0 MGD — 3 points plus 1 point per 1 MGD.

(3)

Unit Process Points:

(a)

Preliminary Treatment and Plant Hydraulics:

(A)

Comminution — 1 point;

(B)

Grit Removal, gravity — 1 point;

(C)

Grit Removal, mechanical — 2 points;

(D)

Screen(s), in-situ or mechanical — 1 point;

(E)

Pump/Lift Station(s) — 2 points;

(F)

Flow Equalization — 1 point.

(b)

Primary Treatment:

(A)

Community Septic Tank(s) — 2 points;

(B)

Clarifier(s) — 5 points;

(C)

Flotation Clarifier(s) — 7 points;

(D)

Chemical Addition System — 2 points;

(E)

Imhoff Tank — 3 points.

(c)

Secondary, Advanced, and Tertiary Treatment:

(A)

Low Rate Trickling Filter(s) — 7 points;

(B)

High Rate Trickling Filter(s) — 10 points;

(C)

Trickling Filter — Solids Contact System — 12 points;

(D)

Activated Sludge — 15 points;

(E)

Pure Oxygen Activated Sludge — 20 points;

(F)

Activated Bio Filter Tower less than 0.1 MGD — 6 points;

(G)

Activated Bio Filter Tower greater than 0.1 MGD — 12 points;

(H)

Rotating Biological Contactors 1 to 4 shafts — 7 points;

(I)

Rotating Biological Contactors, 5 or more shafts — 12 points;

(J)

Stabilization Lagoons, 1 to 3 cells without aeration — 5 points;

(K)

Stabilization Lagoons, 2 or more cells with primary aeration — 7 points;

(L)

Stabilization Lagoons, 2 or more with full aeration — 9 points;

(M)

Recirculating Gravel Filter — 7 points;

(N)

Chemical Precipitation Unit(s) — 3 points;

(O)

Gravity Filtration Unit(s) — 2 points;

(P)

Pressure Filtration Unit(s) — 4 points;

(Q)

Nitrogen Removal, Biological or Chemical/Biological System — 4 points;

(R)

Nitrogen Removal, Designed Extended Aeration Only — 2 points;

(S)

Phosphorus Removal Units — 4 points;

(T)

Effluent Microscreen(s) — 2 points;

(U)

Chemical Flocculation Units — 3 points;

(V)

Chemical Addition System — 2 points;

(W)

Ultrafiltration Membrane(s) — 15 points.

(d)

Solids Handling:

(A)

Anaerobic Primary Sludge Digester(s) without Mixing and Heating — 5 points;

(B)

Anaerobic Primary Sludge Digester(s) with Mixing and Heating — 7 points;

(C)

Anaerobic Primary and Secondary Sludge Digesters — 10 points;

(D)

Sludge Digester Gas reuse — 3 points;

(E)

Aerobic Sludge Digester(s) — 8 points;

(F)

Sludge Storage Lagoon(s) — 2 points;

(G)

Sludge Lagoon(s) with aeration — 3 points;

(H)

Sludge Drying Bed(s) — 1 point;

(I)

Sludge Air or Gravity Thickening — 3 points;

(J)

Sludge Composting, In Vessel — 12 points;

(K)

Sludge Belt(s) or Vacuum Press/Dewatering — 5 points;

(L)

Sludge Centrifuge(s) — 5 points;

(M)

Sludge Incineration — 12 points;

(N)

Sludge Chemical Addition Unit(s) — 2 points;

(O)

Non-Beneficial Sludge Disposal — 1 point;

(P)

Beneficial Sludge Utilization — 3 points;

(Q)

Solids Reduction Processing — 4 points.

(e)

Disinfection:

(A)

Liquid Chlorine Disinfection — 2 points;

(B)

Gas Chlorine Disinfection — 5 points;

(C)

On-Site Chlorine Generation of Disinfectants — 5 points;

(D)

Dechlorination System — 4 points;

(E)

Other disinfection systems including ultraviolet and ozonation — 5 points.

(4)

Effluent Permit Requirements Points:

(a)

Minimum of secondary effluent limitations for BOD and/or Total Suspended solids — 2 points;

(b)

Minimum of 20 mg/L BOD and/or Total Suspended Solids — 3 points;

(c)

Minimum of 10 mg/L BOD and/or Total Suspended Solids — 4 points;

(d)

Minimum of 5 mg/L BOD and/or Total Suspended Solids — 5 points;

(e)

Effluent limitations for effluent oxygen — 1 point.

(5)

Variation in Raw Waste Points. Points in this category will be awarded only when conditions are extreme to the extent that operation and handling procedure changes are needed to adequately treat the waste due to variation of raw waste:

(a)

Recurring deviations or excessive variations of 100% to 200% in strength or flow — 2 points;

(b)

Recurring deviations or excessive variations of more than 200% in strength or flow, or conveyance and treatment of industrial wastes covered by a pretreatment program — 4 points.

(c)

Septage or truck hauled waste — 2 points.

(6)

Sampling and Laboratory Testing Points:

(a)

Sample for BOD, Total Suspended Solids performed by outside laboratory — 2 points;

(b)

BOD or Total Suspended Solids analysis performed at treatment plant — 4 points;

(c)

Bacteriological analysis performed by outside laboratory — 1 point;

(d)

Bacteriological analysis performed at treatment plant — 2 points;

(e)

Nutrient, Heavy Metals, or Organics analysis by outside laboratory — 3 points;

(f)

Nutrient, Heavy Metals or Organics analysis performed at treatment plant — 5 points.

Source: Rule 340-049-0025 — Criteria for Classifying Wastewater Treatment Systems, https://secure.­sos.­state.­or.­us/oard/view.­action?ruleNumber=340-049-0025.

Last Updated

Jun. 8, 2021

Rule 340-049-0025’s source at or​.us