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

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Practical Quantitation Limit GuidancePresentation
to WQ ForumNovember 20, 2006
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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

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PQL Guidance Development

• Work Group Representation
• WQCD, HMWMD, and CDPHE Lab
• Analytical laboratories
• Municipalities
• Industries
• Consultants

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Technical/Policy Approach

• Continue Prescriptive PQLs
• Sets minimum requirement for all laboratories
• Level playing field
• Reduces option of lab shopping

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Work Group Tasks

• Update PQLs for reg. 61 listed compounds
• Establish PQLs for new compounds
• Update policy for site-specific PQLs

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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

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Clarifications to Noticed Guidance

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

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PQL Determination Process

• Vision Statement
• Develop a process to identify appropriate
  analytical PQLs

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PQL Selection Process

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

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Objectives

• PQLs lt 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

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Issues and Resolutions

• PQL for robust method gt 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

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Description of Selection Process

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

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Recommendation

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

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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

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Commission Questions
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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