PREMISES FOR DEVELOPING AND APPLYING SEDIMENT QUALITY OBJECTIVES

1
PREMISES FOR DEVELOPING AND APPLYING SEDIMENT
QUALITY OBJECTIVES

• Presented and (mostly) agreed upon during the
  October 27, 2004 meeting of the Advisory
  Committee

2
BASIC GOAL OF SQO APPROACH

• The primary goal is to determine if beneficial
  uses at a station are impaired
• Assessment of larger areas and/or waterbodies is
  a secondary goal
• The method for aggregating site-specific data for
  larger assessments may depend to some extent on
  the specific application (e.g., waterbody
  evaluation for 303d listing, dredging)

3
UNDERLYING PHILOSOPHY

• At least two lines of evidence (or legs of the
  triad) are necessary to conclude a beneficial use
  is impaired
• One line of evidence alone is too subject to
  error
• Need to demonstrate both exposure and effect

4
TECHNICAL APPROACH

• Develop quantitative scaling of indicator values
• Avoid simple binary thresholds
• because
• Thresholds are uncertain and less responsive to
  degrees of change or difference
• Scaled values are more useful for tracking trends
• Scaled values produce more meaningful assessments

5
APPLICATION GUIDANCE

• Challenge is to create a consistent MLOE
  application
• Primary users will often be inexperienced
  engineers
• BPJ not a realistic option
• Goal is to develop a cookbook that
• Addresses specific applications
• Relates SQO to existing regulatory frameworks
• Clearly states how SQO should NOT be used

6
BENEFICIAL USE PROTECTION CATEGORIES

• Aquatic life (Infaunal) effects
• Human health effects
• Fish and wildlife effects

7
INDEPENDENT ASSESSMENT OF BENEFICIAL USES

• MLOE will be used within each beneficial use, and
  independent assessments will be conducted for
  each
• If any one beneficial use fails, the station
  fails, i.e., assessments are not additive across
  beneficial uses
• However, the aquatic life use will probably take
  precedence because of state of knowledge and
  availability of data

8
GENERAL CONCERNS RELATED TO IMPLEMENTATION

• Need strategies and guidance for working with
  imperfect information, e.g., burden shifting
• Aggregating station-by-station assessments within
  context of specific regulatory frameworks
• Constraints on use of SQO, i.e., what they are
  NOT suited for

9
SPECIFIC IMPLEMENTATION ISSUES

• Station assessment
• Chemistry that is not bioavailable
• Imperfect information
• Burden shifting mechanism
• Incorporating other information
• 303d listing guidance
• stations needed for system assessment
• Toxic response but low chemistry and OK benthos
• Data collection after listing

10
STATION UNAVAILABLE CHEMICALS

• Hard to define and demonstrate potential for
  impact
• Would depend on plausible mechanism(s)
• Possible long list of mechanisms
• Station might never get clean bill of health
• Margin of safety not clear if have elevated
  chemistry but OK toxicity and benthos
• Establish burden shifting incentives that foster
  further investigation

11
STATION IMPERFECT INFORMATION

• Potential problems with data quality, recency,
  seasonality, conflicting requirements
• Need minimum data requirements
• Minimum list of chemicals to be measured
• Use data less than 5 years old
• BRI developed for summer being assessed for
  other seasons
• BRI requires surficial sediments dredging
  requires deeper cores
• Guidance must address all these issues

12
STATION BURDEN SHIFTING MECHANISM

• Value of incentives vs. rigid requirements
• Acknowledgment of imperfect information, varied
  application scenarios
• SQOs and related guidance should define several
  specific burden shifting mechanisms
• What are thresholds for triggering burden
  shifting?
• What is the time frame within which incentives
  play out?

13
INCORPORATING OTHER INFORMATION

• Triad data may not always be definitive
• Other data may be valuable in interpreting Triad
  results
• Need to avoid potential for dueling data
• Three Triad legs should trump other data for
  final decision making

14
303d LISTING APPLICATION

• 303d guidance unclear about spatial distribution
  of samples needed for assessment
• SQO guidance should somehow address this
• Guidance should include incentives for further
  investigation when results equivocal
• Questions re link between finding of impairment
  and identification of specific chemical cause
• 303d and TMDL processes focus on specific causes
• Link between SQO and 303d / TMDL desirable
• Examine 303d / TMDL guidance for potential
  linkages