1. The Nuts & Bolts of TBLL Development
Duyen Tran
OMI, Inc.

2. The “Bible”
EPA Guidance Manual on the Development and Implementation of Local Discharge Limitations Under the Pretreatment Program
EPA 833-R A
July 2004

3. 7-steps process Preliminary Data Collection
Identify Pollutants of Concern
Sampling Plan
Data Collection & Evaluation
Calculation
Technical Review
TBLL Submission

4. Preliminary Data Collection
Receiving stream designation
Water Quality Standards for the designated receiving stream
Most recent priority pollutant scans on plant influent (include analyses of additional pollutants specified in State Water Quality Standards)

5. Identify Pollutants of Concern (POC)
Pollutants with concentration greater than 0.1 mg/l in the influent scan, adjust for inflow/infiltration if the plant has I/I problem
Pollutants associated with historical plant problems
Fifteen EPA’s POCs: Cd, Cr, Cu, Pb, Ni, Zn, As, CN, Ag, Hg, Mo, Se, BOD, TSS, Ammonia

6. Sampling Plan
Review historical data on pollutants of concern for: influent, effluent, primary effluent, sludge, industrial effluent, inhibition data, background (domestic & commercial)
Reject data that is anomaly
Reject data that does not meet laboratory QA/QC or required MDLs

7. Sampling Plan (cont’d)
In lieu of at least 6 months of historical data, collect at least 6 consecutive days of samples for influent, effluent, and background
Consider plant retention time when collecting new influent and effluent data
In all cases, obtain the most representative collection of data for TBLL calculation

8. Data Collection & Evaluation
NPDES Permit
State WQS
503 Sludge Criteria
Receiving Stream, 7Q10 or 7Q2
Plant diagram and description of plant processes
POTW Flow
Digester Flow
Industrial Flows
Background Flow (Domestic + Commerical)

9. Data Collection & Evaluation
Review analytical data for:
Chain of custody
Laboratory QA/QC
MDLs
Reject data that appears to be anomaly or does not meet the above criteria
Document the data evaluation process

10. Calculation Plant Removal Efficiency, % Allowable Headworks Loadings
Background (Domestic) Loadings
Derive Maximum Allowable Headworks Loadings (MAHL)
Maximum Allowable Industrial Loadings (MAIL)

11. Allowable Headworks Loadings (AHL)
Calculate AHL for:
Water Quality Standards
NPDES Permit
Process Inhibition/Operational Problems
Sludge Disposal Criteria

13. Maximum Allowable Industrial Loadings, MAIL
MAIL = MAHL - (Background + Safety Factor)

15. Allocation Uniform Concentration Industrial Contributory Flow
Mass Proportion Method
Selected Industrial Reduction Method

16. Applications of Local Limits
Industrial Discharge Permit Limits Calculation
New Discharge Permit Consideration
Plant Loadings Assessment

17. Technical Review
Technical Support Staff
City Engineers
City Council

18. TBLL Submission
Use State guidelines and checklist on program modification and submittal
Prepare a professional certification
Incorporate the new technically based local limits to the sewer use ordinance (SUO)
Submit three copies of the TBLL study and revised SUO to the State

20. Resources
EPA Guidance Manual on the Development and Implementation of Local Discharge Limitations Under the Pretreatment Program
EPA Supplemental Manual
EPA Region VI TBLL Guidelines

21. Duyen Tran, Project Manager OMI, Inc. City of Fayetteville WWTP
1400 N. Fox Hunter Road
Fayetteville, AR
(479)