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

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

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

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

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

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

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

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

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

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

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

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

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

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

Commission Questions

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