Texas Wastewater Facility Categories & Operator Staffing Requirements

Texas domestic wastewater treatment facilities are classified according to treatment process and permitted daily average flow. The facility category determines the minimum license level required for the chief operator and affects staffing expectations for daily operation and shift supervision.

For operators, it is important to distinguish between the operator license class and the facility category. Wastewater treatment operator licenses are Classes D, C, B, and A. A treatment facility is also assigned a category based on its treatment process, size, and complexity.

Why Facility Category Matters

The Texas Commission on Environmental Quality, or TCEQ, uses facility classification to determine the minimum level of operator qualification required for a domestic wastewater treatment plant.

The classification system considers:

• treatment process;
• permitted daily average flow;
• process complexity;
• special treatment requirements;
• other unusual operating or maintenance conditions.

Minimum Chief Operator Level

The required chief operator license generally corresponds to the facility category.

• Category D facility: minimum Class D;
• Category C facility: minimum Class C;
• Category B facility: minimum Class B;
• Category A facility: minimum Class A.

A higher-level licensed operator can satisfy a lower minimum requirement.

Facility Category and Operator Class Are Different Concepts

A useful exam distinction is:

• facility category describes the wastewater treatment plant;
• operator class describes the individual operator's license.

The letters correspond, but they refer to different things.

No-Discharge Treatment Systems

For no-discharge treatment systems using a disposal system other than subsurface area drip dispersal, the current minimum chief operator level is generally:

Class D

for all permitted flows, unless another condition causes the facility to be classified higher.

Subsurface Area Drip Dispersal

A no-discharge facility using a subsurface area drip dispersal system currently requires at least:

Class C

as the minimum chief operator level.

Pond Systems

Pond systems preceded by Imhoff tanks, primary clarifiers, or facultative lagoons are categorized according to permitted daily average flow.

Pond Systems at 1.0 MGD or Less

For these pond systems with a permitted daily average flow of:

1.0 MGD or less

the minimum chief operator level is generally:

Class D

Pond Systems Greater Than 1.0 MGD

For these pond systems with permitted daily average flow:

greater than 1.0 MGD

the minimum chief operator level is generally:

Class C

Extended Aeration and Oxidation Ditch Systems

Activated sludge facilities operating in extended aeration mode and oxidation ditch systems use the following current classification thresholds.

0.10 MGD or Less

Permitted daily average flow:

0.10 MGD or less

Minimum chief operator:

Class D

Greater Than 0.10 MGD to 1.0 MGD

Minimum chief operator:

Class C

Greater Than 1.0 MGD to 10.0 MGD

Minimum chief operator:

Class B

Greater Than 10.0 MGD

Minimum chief operator:

Class A

Activated Sludge Other Than Extended Aeration

Activated sludge facilities using modes other than extended aeration have different flow thresholds.

0.050 MGD or Less

Permitted daily average flow:

0.050 MGD or less

Minimum chief operator:

Class D

Greater Than 0.050 MGD to 1.0 MGD

Minimum chief operator:

Class C

Greater Than 1.0 MGD to 10.0 MGD

Minimum chief operator:

Class B

Greater Than 10.0 MGD

Minimum chief operator:

Class A

Fixed-Film Processes

Trickling filters, rotating biological contactors, and other fixed-film treatment processes use another set of flow thresholds.

0.50 MGD or Less

Permitted daily average flow:

0.50 MGD or less

Minimum chief operator:

Class D

Greater Than 0.50 MGD to 2.0 MGD

Minimum chief operator:

Class C

Greater Than 2.0 MGD to 10.0 MGD

Minimum chief operator:

Class B

Greater Than 10.0 MGD

Minimum chief operator:

Class A

Combination Treatment Processes

A wastewater treatment facility can use more than one treatment process.

If the processes fall into different facility categories, TCEQ assigns the facility to the:

higher category

rather than averaging the categories or using the process that treats the largest flow.

Example: Combination Facility

Suppose a facility contains one process that would normally be Category C and another process that would normally be Category B.

The facility is classified at the higher level:

Category B

Executive Director Can Increase the Category

TCEQ can assign a higher facility category when the plant contains unusually complex processes or presents unusual operation or maintenance conditions.

This means the classification table is not always the final determination for every unusual plant.

Special Reclassification of Category D Facilities

Certain conditions cause an otherwise Category D wastewater treatment facility to be reclassified as Category C.

Anaerobic Sludge Digestion

A Category D facility is reclassified as Category C if it incorporates anaerobic sludge digestion, except for the limited Imhoff-tank situation identified by TCEQ.

Nutrient Reduction

A Category D facility is also reclassified as Category C when the facility permit requires nutrient reduction.

Very Stringent BOD or TSS Limits

A Category D facility is reclassified as Category C when the permit requires final effluent to meet a daily five-day average BOD or TSS concentration:

less than 10 mg/L

Why These Reclassification Rules Matter

A small facility is not always a Category D facility.

Process complexity and permit requirements can raise the required operator level even when flow is low.

Chief Operator

The chief operator is the licensed operator responsible for the operation of the wastewater treatment facility at the required license level.

The required chief operator class depends on the facility category.

Minimum Operating Coverage

TCEQ currently requires every wastewater treatment facility to be operated for at least:

five days per week

by:

• the licensed chief operator; or
• another operator holding the required license level or higher.

Seven-Day Availability

The licensed chief operator or operator holding the required license level or higher must be available by:

• telephone; or
• pager

seven days per week.

Available Does Not Always Mean Physically Present

The rule distinguishes between required operating presence and required availability.

The chief operator or appropriately licensed operator must meet the facility's operational requirements and be reachable seven days per week.

Shift Operation

Larger or continuously operated facilities can require multiple shifts.

When the chief operator is not physically supervising a shift, that shift must have an operator in responsible charge.

Operator in Charge

For shift operation, the operator in charge must hold a license:

not less than one level below the category of the facility.

Example: Category B Plant

If a Category B facility operates multiple shifts and the chief operator is not on-site during a particular shift, the operator in charge for that shift must generally hold at least:

Class C

Example: Category A Plant

At a Category A facility, a shift without the chief operator must generally be supervised by an operator holding at least:

Class B

Higher-Level Operators Are Acceptable

If the minimum is Class C, an operator holding Class B or Class A can satisfy that minimum.

The rule establishes the minimum, not the only acceptable license.

Scheduled TCEQ Inspections

Either the licensed chief operator or the licensed operator in charge must be present for scheduled TCEQ inspections.

This ensures that an appropriately responsible operator is available to explain facility operation and compliance conditions.

Chief Operator Responsibilities

Chief operator responsibilities can include oversight of:

• treatment operation;
• process control;
• staffing;
• operator assignments;
• maintenance;
• monitoring;
• permit compliance;
• records;
• response to abnormal conditions.

Operators Working Below the Chief Level

A wastewater facility can employ operators holding licenses below the chief operator level when allowed.

However, lower-level operators must work within the supervision and staffing structure required for the facility.

License Level Does Not Automatically Equal Job Title

A Class A operator is not automatically the chief operator simply because the operator holds the highest license.

Chief operator is a position of responsibility assigned by the facility or permittee.

Permittee Responsibility

The facility permittee is responsible for ensuring that the treatment plant is operated by appropriately licensed personnel.

This can involve:

• employing licensed operators;
• contracting with licensed operators;
• contracting with a registered wastewater operations company.

Wastewater Operations Companies

A nongovernmental organization that contracts to operate domestic wastewater treatment facilities or collection systems can be required to register with TCEQ as a wastewater operations company.

This registration requirement is separate from the individual operator license.

Operator License and Company Registration Are Different

An individual operator holds an occupational license.

An operations company can be subject to separate TCEQ registration requirements.

Facility Category Can Change

A facility category can change when:

• permitted flow increases;
• treatment processes change;
• permit limits become more stringent;
• nutrient reduction is added;
• process complexity increases.

Operators Should Review Permit Amendments

A plant expansion or permit amendment can affect the required chief operator level.

The facility should verify staffing requirements when regulatory or process changes occur.

Permitted Flow Versus Actual Daily Flow

The classification table uses permitted daily average flow, not simply the flow measured on one particular day.

An operator should not reclassify the plant informally because actual flow happens to be temporarily lower.

MGD Conversion

MGD means million gallons per day.

For example:

0.10 MGD = 100,000 gpd

0.50 MGD = 500,000 gpd

1.0 MGD = 1,000,000 gpd

10.0 MGD = 10,000,000 gpd

Example: Extended Aeration Plant at 0.08 MGD

0.08 MGD equals:

80,000 gpd

Because this is 0.10 MGD or less, the basic classification table indicates a minimum:

Class D chief operator

unless another condition raises the facility category.

Example: Extended Aeration Plant at 0.75 MGD

The permitted flow is greater than 0.10 MGD but not greater than 1.0 MGD.

The minimum chief operator is:

Class C

Example: Extended Aeration Plant at 4 MGD

The permitted flow is greater than 1.0 MGD but not greater than 10.0 MGD.

The minimum chief operator is:

Class B

Example: Extended Aeration Plant at 15 MGD

The permitted flow is greater than 10.0 MGD.

The minimum chief operator is:

Class A

Example: Conventional Activated Sludge at 0.08 MGD

This facility uses activated sludge other than extended aeration.

Because 0.08 MGD is greater than the 0.050 MGD Class D threshold, the minimum chief operator is:

Class C

Example: Trickling Filter at 0.40 MGD

The permitted flow is 0.50 MGD or less.

The minimum chief operator is:

Class D

Example: Trickling Filter at 1.5 MGD

The permitted flow is greater than 0.50 MGD but not greater than 2.0 MGD.

The minimum chief operator is:

Class C

Example: Small Plant with Nutrient Reduction

A plant that would otherwise qualify as Category D can be reclassified as Category C when the permit requires nutrient reduction.

Example: Small Plant with Very Low BOD Limit

If the permit requires a final effluent daily five-day average BOD concentration below 10 mg/L, an otherwise Category D facility is reclassified as Category C.

Example: Two-Process Facility

A plant combines:

• a Category C process;
• a Category B process.

The facility is classified:

Category B

Example: Category C Facility with Multiple Shifts

If the chief operator is absent from a shift, the operator in charge must generally be licensed at least one level below Category C.

The minimum is therefore:

Class D

Example: Category A Facility with Multiple Shifts

The minimum operator-in-charge level for a shift without the chief operator is:

Class B

Do Not Confuse Treatment Facility Categories with Collection Categories

Texas wastewater collection systems use a different classification system:

• Category I;
• Category II;
• Category III.

Those collection-system categories are based on collection-system flow and required collection supervision.

This article addresses wastewater treatment facilities, not collection-system categories.

Treatment Operators Can Perform Collection Duties

A licensed wastewater treatment facility operator may perform duties related to operation and maintenance of both wastewater treatment facilities and wastewater collection systems.

A separate collection license is not necessarily required for a wastewater treatment operator performing those duties.

Collection Operators Have a Narrower Scope

A licensed wastewater collection operator may perform duties relating to wastewater collection systems but does not automatically have authority to perform wastewater treatment-facility operator duties.

Common Facility Classification Mistakes

• Using actual daily flow instead of permitted daily average flow.
• Assuming every activated sludge plant uses the same flow thresholds.
• Ignoring the difference between extended aeration and other activated sludge modes.
• Ignoring special Category D reclassification conditions.
• Using the lower category when a facility has multiple treatment processes.
• Assuming a small plant always requires only a Class D chief operator.
• Confusing treatment-facility categories with collection-system Categories I, II, and III.
• Failing to provide appropriate shift supervision.
• Assuming the chief operator must be physically present 24 hours per day.
• Failing to review operator requirements after facility expansion or permit modification.

A Practical Facility Classification Review

1. Identify the treatment process.
2. Identify the permitted daily average flow.
3. Locate the appropriate TCEQ classification range.
4. Determine the basic facility category.
5. Check for multiple treatment processes.
6. Check for anaerobic digestion.
7. Check for nutrient-reduction requirements.
8. Check for stringent BOD or TSS permit limits.
9. Check whether TCEQ has assigned a higher category.
10. Determine the minimum chief operator license.

A Practical Staffing Review

1. Identify the facility category.
2. Verify the chief operator license.
3. Verify operation by the chief operator or required-level operator at least five days per week.
4. Verify seven-day telephone or pager availability.
5. Identify whether shift operation is necessary.
6. Verify operator-in-charge licensing for shifts without the chief operator.
7. Ensure an appropriate operator is available for scheduled TCEQ inspections.

What to Remember for the Exam

• Texas domestic wastewater treatment facility categories are based primarily on treatment process and permitted daily average flow.
• The minimum chief operator license generally matches the facility category: D, C, B, or A.
• A facility with treatment processes in different categories is assigned the higher category.
• TCEQ can increase a facility category for unusually complex processes or unusual operating conditions.
• No-discharge systems other than subsurface area drip dispersal generally have a Class D minimum at all flows unless another condition raises the category.
• Subsurface area drip dispersal facilities require at least a Class C chief operator.
• Extended aeration and oxidation ditch systems use thresholds of 0.10, 1.0, and 10.0 MGD.
• Activated sludge systems other than extended aeration use thresholds of 0.050, 1.0, and 10.0 MGD.
• Trickling filters, RBCs, and other fixed-film processes use thresholds of 0.50, 2.0, and 10.0 MGD.
• An otherwise Category D facility becomes Category C when certain higher-complexity conditions apply.
• Those conditions include certain anaerobic sludge digestion, nutrient reduction, or final BOD or TSS requirements below 10 mg/L.
• Facility classification uses permitted daily average flow, not the flow on a single day.
• Every treatment facility must be operated at least five days per week by the chief operator or an operator holding the required license level or higher.
• The chief operator or required-level operator must be available by telephone or pager seven days per week.
• For shift operation, a shift without the chief operator must have an operator in charge licensed at not less than one level below the facility category.
• Either the chief operator or operator in charge must be present for scheduled TCEQ inspections.
• A higher operator class can satisfy a lower minimum requirement.
• Wastewater treatment facility categories D through A are different from wastewater collection Categories I through III.
• A wastewater treatment operator may perform both treatment and collection duties within the applicable rules.
• Always recheck facility classification when flow, treatment process, or permit requirements change.