1 of 27 The EPA 7-Step DQO Process Step 5 - Define Decision Rules (15 minutes) Presenter: Sebastian Tindall Day 2 DQO Training Course Module 5

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The EPA 7-Step DQO Process

Step 5 - Define Decision Rules

(15 minutes)

Presenter: Sebastian Tindall

Day 2 DQO Training CourseModule 5

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Step Objective: This step combines Steps

1 - 4 to produce the following major elements to form decision rules:– Parameter of interest

– Unit of decision making

– Action level

– Alternative actions

Step 5: Define Decision Rules

Step 4: Specify Boundaries

Step 2: Identify Decisions

Step 3: Identify Inputs

Step 1: State the Problem

Step 5: Define Decision Rules

Step 6: Specify Error Tolerances

Step 7: Optimize Sample Design

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Alternative Actions Step 2

Population of Interest

Step 4

Basis for Defining Action Level

Step 3

Step 5- Define Decision Rules

Develop a Decision Rule

If/Then Decision

Rule Statements

Information IN Actions Information OUT

From Previous Step To Next StepPrincipal Study Question

Step 2

Specify the Parameter of Interest

Confirm the Action Level

Information Required to Resolve Decision Statement

Step 3

Unit of Decision Making

Step 4

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Major Elements of a Decision Rule: Parameter of Interest

– Population Parameter

Background

– Sample Statistic

– Environmental Variable• Chemical/Physical attribute in the population• Levels measured (Quantity)

Unit of Decision Making– Geographic Area/Volume

– Timeframe

– Population

Action Level Alternative Action(s)

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Background




– Timeframe

– Population


A descriptive measure (such as a true mean, median, or proportion)that specifies the characteristic or attribute that the decision maker would like to know about the population. By definition, this will always remain unknown. Note: The purpose of anydata collection design is to produce environmental data thatcan be used as a reasonable estimate of this population parameter.

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Background




– Timeframe

– Population


The sample statistic, e.g., the sample mean, which is obtained from the sampling data is used to estimate the population parameter. It is often the upper confidence limit about the sample mean.

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Background




– Timeframe

– Population


The variable is both the COPC (chemical and physical) and the level measured. Examples of the level are concentration or activity or result.

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Background




– Timeframe

– Population


The smallest, most appropriate subset (sub-population) for which separatedecisions will be made.

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Background




– Timeframe

– Population


Spatial Boundary

Temporal Boundary

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Background




– Timeframe

– Population


The total number of objects (samples of soil or sludge or sediment or air, etc.), that are contained within the spatial unit to be studied

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Background




– Timeframe

– Population


A measurement threshold value ofthe parameter of interest that provides the criterion for choosingamong alternative actions.

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Background




– Timeframe

– Population


The actions that the decision maker wouldtake depending on the value of the sample statistic which is an estimate of thepopulation parameter.

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Step 4


Step 3


If/Then Decision

Rule Statements



Step 2




Step 3


Step 4

The purpose of the data collection design is to produceenvironmental data that can be used as a reasonable estimateof the population (true) parameter.


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Step 4


Step 3


If/Then Decision

Rule Statements



Step 2




Step 3


Step 4

If not done in Step 3, specify the numerical value that would cause a person to choose between alternative actions.

Confirm that the action level is greater than the detection/quantitation limits for the potential measurement methods identified in Step 3.


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Step 4


Step 3


If/Then Decision

Rule Statements



Step 2




Step 3


Step 4

Develop a decision rule as an “if…then…” statement that incorporates the parameter of interest, the unit of decision making, the action level, and the action(s) that would result from resolution of the decision.


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Decision Rule

General Format

If the [parameter of interest (4 elements)] within the [unit of decision (3 elements)] is > the [action level], then take [alternative action A]; or take [alternative action B].

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Decision Rule Example 1

If the [“true” mean (as estimated by the 95%

UCL of the sample mean) concentration of

U-238] within the [surface soil in the

perimeter of the backyard to a depth of 6

inches] is > [20 pCi/g], then [dispose of soil in a radiological landfill]; or [leave the soil in place].

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If the [“true” mean (as estimated by the one sided 90% UCL of the sample mean) concentration of cadmium] within [the metal turnings in a 55 gallon drum] is > [1 mg/kg], then [the metal turnings will be considered hazardous and will be disposed of in a RCRA facility]; or [the metal turnings will be disposed of in a municipal landfill].

Decision Rule Example 2

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If the vadose zone soil moisture content, contaminant concentration profiles, and soil physical properties from the 1454 site exceed or deviate significantly from the conceptual model, an additional evaluation will be performed to assess priority of performing further analysis.

The data gathered from the characterization boring located at the 1454 site combined with historical process data and geophysical logging (high resolution spectral gamma-ray and neutron logging) of existing wells located in the vicinity of the 1455 site can be used to create an analogous model for the 1455 site. If the data collected from characterization of the 1454 site and the geophysical logging data from the existing wells located near the 1455 site support the conceptual model, the analogous unit approach is valid for the 1455 site.

“Typical” Decision Rules

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Step 5- Decision Rules CS

EEnnvviirroonnmmeennttaall VVaarriiaabbllee DS

# Population Parameter

SSaammppllee SSttaattiissttiiccss

AAttttrriibbuuttee UUnniitt ooff MMeeaassuurree

Unit or Scale of Decision Making RReellaattiioonnsshhiipp AAccttiioonn

LLeevveell ((aa)) AAAA ##11 RReellaattiioonnsshhiipp AAAA ##22

If the true mean concentration

as estimated by 95% UCL of the sample mean

of the lead, measured in mg/kg

Within the foot print and run-off area from 0” to 6” depth

Is greater than

250 mg/kg Lead

then conduct remedial action

or

take no further action is required



of the uranium, measured in mg/kg


Is greater than

240 mg/kg Uranium


or




of the TPH, measured in mg/kg


Is greater than

100 mg/kg TPH


or


1



of the PCBs, measured in mg/kg


Is greater than

1 mg/kg PCBs (total Aroclors)


or


a State Regulations (which are the same or more restrictive that federal regulations). State Regulations 173-4901 also typically specify the required assumptions for risk assessment and specify the degree of site specific information required.

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Decision Rule 1a

If the true mean (as estimated by the 95% UCL of the sample mean) concentration of the contaminant within the surface soil to a depth of 6 inches of the Pad footprint and run-off zone is > the AL, then conduct remedial action; or take no further action.

Contaminates/Action Limits• 250 mg/kg Lead• 240 mg/kg Uranium• 100 mg/kg TPH• 1 mg/kg PCBs (total Aroclors)

CS

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If the true mean (as estimated by the 95% UCL of the sample mean) concentration of the contaminant within the surface soil to a depth of 6 inches of the radial buffer zone excluding the Pad and run-off zone is > the AL, then conduct remedial action; or take no further action.


CSDecision Rule 1b

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If the true mean (as estimated by the 95% UCL of the sample mean) concentration of the contaminant within the subsurface soil to a depth of 6” to 10’ of the Pad footprint and run-off zone is > the AL, then conduct remedial action; or take no further action.


CSDecision Rule 2a

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If the true mean (as estimated by the 95% UCL of the sample mean) concentration of the contaminant within the surface soil to a depth of 6” to 10’ of the radial buffer zone excluding the Pad and run-off zone is > the AL, then conduct remedial action; or take no further action.


CSDecision Rule 2b

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Step 5 - Summary After data are obtained and undergo Data

Quality Assessment, decision rules are used to make the decisions

The decision rules encompass the logic used and include inputs from Steps 1-4 and 6

One may need to perform Step 6 and then update Step 5 to include the statistical decision criteria

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Step 4


Step 3


If/Then Decision

Rule Statements



Step 2




Step 3


Step 4


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End of Module 5

Thank you

Documents

1 of 27 The EPA 7-Step DQO Process Step 5 - Define Decision Rules (15 minutes) Presenter: Sebastian Tindall Day 2 DQO Training Course Module 5