Practical Quantitation Limit Guidance Presentation to WQ Forum November 20, 2006

1. Practical Quantitation Limit GuidancePresentation to WQ ForumNovember 20, 2006

2. Genesis of PQL Guidance • 2003 WQCC Revisions to Reg. 61 • PQLs for organic compounds Removed From Reg. 61 • WQCD directed to develop guidance • PQL Work Group created

3. PQL Guidance Development • Work Group Representation • WQCD, HMWMD, and CDPHE Lab • Analytical laboratories • Municipalities • Industries • Consultants

4. Technical/Policy Approach • Continue “Prescriptive” PQLs • Sets minimum requirement for all laboratories • Level playing field • Reduces option of “lab shopping”

5. Work Group Tasks • Update PQLs for reg. 61 listed compounds • Establish PQLs for “new” compounds • Update policy for site-specific PQLs

6. Applicability of PQL Guidance • Distinction between WQCD and “implementing agencies” • Implementing agencies must use guidance or develop agency-specific PQLS • PQLs only identified for compounds with EPA-approved methods

7. Clarifications to Noticed Guidance • Implementing agencies not bound by EPA-approved methods • PQLmin. Must be used if PQLrobust > limit or WQS, as appropriate • Site-specific PQL based on existing quality assured work in lieu of lab study

8. PQL Determination Process • Vision Statement: • Develop a process to identify appropriate analytical PQLs

9. PQL Selection Process • Objectives of Work Group in Developing Process • Issues Addressed During Work Group Meetings • Description of Process

10. Objectives • PQLs < water quality standards • No high cost science experiments • Use robust methods to greatest extent possible • Minimize number of site-specific studies • Base on published values where identified • Process must be reproducible

11. Issues and Resolutions • PQL for robust method > water quality standard • Establish PQL minimum • Published values for detection limits much higher than labs can achieve • Conduct lab survey • No published value for detection limit • Use data from lab survey • Many labs cannot achieve published value for detection limit • Allow evaluation of existing QA data for site-specific PQL

12. Description of Selection Process • Logical flow chart • Key steps look at whether: • Robust NPDES method available • Published values for detection limit available • PQL < lowest water quality standard • Results from lab survey < published values • Results in PQL robust, PQL minimum (if necessary), PQL TBD, or Method TBD

13. Recommendation • Recommend one or more of the strategies • Summarize the results if things go as proposed • What to do next • Identify action items

14. Recommendations • Subcommittee to apply process to Inorganic Parameters • Subcommittee to address “emerging contaminants” • Subcommittee to review site-specific PQL studies and provide guidance when requested

15. Commission Questions

16. Next Steps • Respond to comments/concerns voiced today and finalize guidance • Identify approach to establish PQLs for inorganic and metals parameters • Establish process for WQCD to approve methods for parameters in Appendix B • Consider future updates to established PQLs/set PQLs for emerging contaminants