1 of 39 The EPA 7-Step DQO Process Step 7 - Optimize Sample Design DQO Case Study 45 minutes Presenter: Sebastian Tindall DQO Training Course Day 3 Module.

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The EPA 7-Step DQO Process

Step 7 - Optimize Sample DesignDQO Case Study

45 minutes

Presenter: Sebastian Tindall

DQO Training CourseDay 3

Module 20

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Information IN Actions Information OUT

From Previous Step To Next Step

Select the optimal sample size that satisfies the DQOs for each data collection design option

For each design option, select needed mathematical expressions

Check if number of samples exceeds project resource constraints

Decision Error Tolerances

Gray Region

Optimal Sample Design

Go back to Steps 1- 6 and revisit decisions. Yes

No

Review DQO outputs from Steps 1-6 to be sure they are internally consistent

Step 7- Optimize Sample Design

Develop alternative sample designs

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Terminal Objective

To be able to use the output from the previous DQO Process steps to select sampling and analysis designs and understand design alternatives presented to you for a specific project

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Sampling Approaches

Sampling Approach 1– Simple Random

– Traditional fixed laboratory analyses

Sampling Approach 2– Systematic Grid

– Field analytical measurements

– Computer simulations

– Dynamic work plan

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Design ApproachesApproach 1

Collect samples using Simple Random design.

Use predominantly fixed traditional laboratory analyses and specify the method specific details at the beginning of DQO and do not change measurement objectives as more information is obtained

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Approach 1 Sample Design

Plan View

Former PadLocation

RunoffZone

0 50 100 150 ft0 15 30 46 m

BufferZone

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Histogram

0

1

2

3

0 7 14 21 28 35

Pb Concentration (mg/kg)

Fre

qu

en

cy

0

1

2

3

4

0 85 95 105 115

U Concentration

Fre

qu

en

cy0

1

2

3

4

0 1.7 3.4 5.1 6.8

TPH Concentration

Fre

qu

en

cy

0

1

2

3

0 0.8 1.6 2.4 3.2

Arochlor 1260

Fre

qu

en

cy

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“Normal” Approach

Due to using only five samples for initial distribution assessment, one cannot infer a ‘normal’ frequency distribution

Reject the ‘Normal’ Approach and Examine ‘Non-Normal’or ‘Skewed’ Approach

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Pb, U, TPH (DRO/GRO) Because there were multiple COPCs with

varied standard deviations, action limits and LBGRs, separate tables for varying alpha, beta, and (LBGR) delta were calculated

For the U, Pb, and TPH, the largest number of samples for a given alpha, beta and delta are presented in the following table

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Pb, U, TPH Based on Non-Parametric TestSample Sizes Based on Varying Error Tolerances and LBGR

Lead, Uranium, and TPH

Mistakenly Concluding < Action Level

s = 10.5 (U) = 0.01 = 0.05 = 0.10

Sample size formula: 2)(

)(16.1

12

2

2211

n

Width of the Gray Region, () = 240 – 229.5 = 10.5 (total error estimate)

= 0.10 19 12 9

= 0.20 15 9 7

Mis

tak

enly

C

oncl

ud

ing

> A

ctio

n

Lev

el

= 0.30 13 8 5

Width of the Gray Region, () = 240 – 192 = 48 (20% of action level)

= 0.10 4 3 2

= 0.20 4 2 2

Mis

tak

enly

C

oncl

ud

ing

> A

ctio

n

Lev

el

= 0.30 4 2 2

Width of the Gray Region, () = 240 – 120 = 120 (50% of action level)

= 0.10 4 2 2

= 0.20 4 2 1

Mis

tak

enly

C

oncl

ud

ing

> A

ctio

n

Lev

el

= 0.30 4 2 1

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Aroclor 1260: Non-Parametric Test

For PCBs, the Aroclor 1260 has the greatest variance and using the standard deviation results in a wide gray region

The following table presents the variation of alpha, beta and deltas for Aroclor 1260

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Aroclor 1260: Non-Parametric TestSample Sizes Based on Varying Error Tolerances and LBGR

PCBs (based on Aroclor 1260)

Mistakenly Concluding < Action Level

s = 0.88 (A-1260) = 0.01 = 0.05 = 0.10

Sample size formula: 2)(

)(16.1

12

2

2211

n

Width of the Gray Region, () = 1 – 0.12 = 0.88 (total error estimate)a

= 0.10 19 12 9

= 0.20 15 9 7

Mis

tak

enly

C

oncl

ud

ing

> A

ctio

n

Lev

el

= 0.30 13 8 5

Width of the Gray Region, () = 1 – 0.80 = 0.20 (20% of action limit)

= 0.10 296 194 149

= 0.20 229 141 103

Mis

tak

enly

C

oncl

ud

ing

> A

ctio

n

Lev

el

= 0.30 186 108 75

Width of the Gray Region, () = 1 - 0.50 = 0.50 (50% of action limit)

= 0.10 50 33 25

= 0.20 40 24 18

Mis

tak

enly

C

oncl

ud

ing

> A

ctio

n

Lev

el

= 0.30 33 19 13

a The total error estimate for subsurface concentrations exceeds the action limit, thus inappropriately moving the LBGR below zero. Only the surface concentration error estimate is considered here for that reason.

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Approach 1 Sampling Design (cont.) Surface Soils S&A Costs

Lab Analytical Cost Without PCBs

Unit Sample Analysis Cost

Pb by ICP/AES $35U by ICP/AES $65TPH (GRO) by GC $65TPH (DRO) by GC $85

Total USA$ $250

Unit Sample Collection Cost $50AUSCA$ = USC$ + total USA$ $300

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Approach 1 Sampling Design (cont) Sub-surface Soils S&A Costs

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Approach 1 Sampling Design (cont.)

Surface Soils

Lab Analytical Costs for PCBs by GCPolychlorinated biphenyls 150.00$

Total USA$ 150.00$ Unit Sample Collection Cost 50.00$ AUSCA$ = USC$ + total USA$ 200.00$

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Sub-surface Soils

Lab Analytical Costs for PCBs by GCPolychlorinated biphenyls 150.00$

Total USA$ 150.00$ Unit Sample Collection Cost 100.00$ AUSCA$ = USC$ + total USA$ 250.00$

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Approach 1 Based Sampling Design Design for Pb, U, TPH

– Alpha = 0.05; Beta = 0.2; Delta = total error

– The decision makers agreed on collection of 9 surface samples for Pb, U and TPH (GRO & DRO) from each of the two surface strata, for a total of 18 samples using a stratified random design

– For the sub-surface, nine borings/probes will be collected from each of the two subsurface stratum at random locations, collected at a random depth down to 10 feet, to assess migration through the vadose zone, for a total of 18 samples

Design for PCBs– Alpha = 0.05; Beta = 0.20; Delta = 0.50 (50% of the AL)

– The decision makers agreed on collection of 24 surface samples from each of the two surface strata; total of 48 samples using a stratified random design

– For the sub-surface, 24 borings/probes will be collected from each of the two subsurface stratum at random locations, collected at a random depth down to 10 feet for a total of 48 samples (2 X 24)

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Approach 1 Sample Locations(Surface Strata)

Plan View

Former PadLocation

RunoffZone

0 50 100 150 ft0 15 30 46 m

BufferZone

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Remediation Costs*

*Does not include layback area

DR#

Description/Depth Area(ft2)

Volume(yd3)

Cost*

1a Pad & Run-off Zone, 0-6” 12,272 227 $45,4001b Buffer Zone (excluding

Pad and Run-off area), 0-6”42,884 794 $158,800

2a Pad & Run-off Zone,6”-10”

12,272 4,318 $863,600

2b Buffer Zone (excludingPad and Run-off area),6”-10”

42,884 15,089 $3,017,800

* Assume $200 per yd3 for all COPCs

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Approach 1 Based Sampling Design Compare Approach 1 costs versus remediation

costs – Approach 1 S&A costs

• $11,700 (Pb, U, TPH) + $21,600 (PCBs) = $33,300

– Remediation costs• Cost to remediate surface soil under footprint of pad and

buffer area: $204,200• Cost to remediate subsurface soil under footprint of pad and

buffer area: $3,881,400

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Design ApproachesApproach 2: Dynamic Work Plan (DWP) & Field Analytical Methods (FAMs)

Manage uncertainty by increasing sample density by using field analytical measurementsManage uncertainty by including RCRA metals as COPCs Use DWP to allow more field decisions to meet the measurement objectives and allow the objectives to be refined in the field using DWP

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Approach 2 Sampling Design

Phase 1: Pb, U, TPH, PCBs– Perform field analysis of the four strata on-site using XRF

(RCRA metals & U), on-site GC (TPH), and Immunoassay (PCBs) methods. Take into account the chance of false positives at the low detection levels

– This will produce a worse-case frequency distributions and variance for each COPC that will be used to select the proper statistical method and then calculate the number of confirmatory samples for laboratory analysis for the surface and below grade strata

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Phase 1: Metals, TPH, PCBs– Provide detailed SOPs for performance of FAMs: XRF,

GC, & Immunoassay analysis– Divide both surface strata into triangular grids– Use systematic sampling, w/random start (RS), to locate

sample points; sample in center of each grid Pad & Run-off zone

– CSM expects contamination more likely here– 10 ft equilateral triangle: 43.35 ft2

– Pad + Run-off zone = 12,272 ft2

– 283 sample points

Buffer area: – Also 283 sample points – CSM expects contamination less likely here– Thus, grid triangle has larger area


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Phase 1: Pb, U, TPH, PCBs– Sub-surface strata: Pad & Run-off zone

Use Direct Push Technology (DPT) to collect Push at all surface sample points > ALs Minimum sample locations: 40 (+ 10 >ALs) = ~50 Collect sub-surface samples at 3-7-10 feet 50 X 3 = 150 sub-surface samples in this strata Use systematic sampling, w/random start (RS), to locate sample

points

– Buffer area CSM expects contamination less likely here Thus, fewer sample points Same >ALs rationale as above 50 X 3 = 150 sub-surface samples in Buffer area Use systematic sampling, w/RS, to locate sample points


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Stratified Systematic Grid with Random Start(Surface Strata)

Not to scaleTriangles will be adjusted according to Step 7 design

NFootprint ofConcrete Pad(Stratum 1)

Runoff Zone(Stratum 1)

Buffer Zone(Stratum 2)

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Phase 2: Pb, U, TPH, PCBs– Evaluate the FAM results, calculate variance and construct

FDs for each COPC

– Using Monte Carlo method, sample the worst case distribution and evaluate the alpha, beta and delta values and resulting n based on the XRF, on-site GC, and Immunoassay data and select a value (worst case) for n to confirm the FAM data, using traditional laboratory analysis for each of the four strata

– For this Case Study, we will assume that number came out to be 9 per strata or 36 confirmatory lab samples


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FAM ProcedureSW-846, Draft Update IVA

Method 6200

Field portable x-ray fluorescence spectrometry for the determination of elemental concentrations in soil and

sediment

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FAM ProcedureSW-846, Draft Update III

Method 4020

Screening for polychlorinated biphenyls by immunoassay

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FAM Procedure for GROSW-846, Draft Update III

Preparation Method 5030 or 5035(purge and trap methods)

Followed by Analysis Method 8015 B

Non-halogenated organics using GC/FID

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FAM Procedure for DROSW-846, Draft Update III

One of Following Extraction Methods:

• 3540 (soxhlet), • 3541(auto-soxhlet),• 3550 (ultrasonic), or• 3560 (super critical fluid)

Followed by Analysis Method 8015 B:• Non-halogenated organics using GC/FID

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Approach 2 Sampling Design (cont.)Surface Soils SC&SA Costs

U by Field XRF $2RCRA Metals by Field XRF $12TPH (GRO) on-site GC $25TPH (DRO) on-site GC $25

PCBs by IMA kits $50

Total USA$ $114


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Approach 2 Sampling Design (cont)Sub-surface Soils SC&SA Costs

U by Field XRF $2RCRA Metals by Field XRF $12TPH (GRO) on-site GC $25TPH (DRO) on-site GC $25

PCBs by IMA kits $50

Total USA$ $114


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COPC (Method) Number of Samples, n AUSCA$Total SC&SA Cost

U and RCRA Metals (XRF); TPH (On-site GC); PCBs (IMA kits); Surface Soils (strata 1 & 2) 566 $139 $78,674U and RCRA Metals (XRF); TPH (On-site GC); PCBs (IMA kits); Sub-Surface Soils (strata 1&2) 300 $164 $49,200Total $127,874

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Number of Samples, n AUSCA$

Total Sampling and Analytical Cost

Subtotal - Onsite $127,874Pb, U, TPH, PCBs -Surface 18 $425 $7,650Pb, U, TPH, PCBs - Suburface 18 $450 $8,100Subtotal - Lab $15,750

Total Costs On-site and Lab Methods $143,624

Confirmatory Traditional Laboratory Analyses Costs


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Evaluate costs of Approach 2 vs. remediation costs– Sampling and analysis (S&A) costs $143,624– Original budget for S&A $45,000

– Remediation cost Cost to remediate surface soil under footprint of pad and

buffer area: $204,200 Cost to remediate subsurface soil under footprint of pad

and buffer area: $3,881,400


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Approach

# Samples, n On-Site

(Surface / Sub-surface)

# Samples, n Off-Site

(Surface / Sub-surface)

Total Sampling and Analytical Cost

1 none 66/66 $33,3002 566/300 18/18 $143,624

Comparison Costs

Remediation Costs:•Surface - $204,200•Sub-surface - $3,881,400


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Measure gasoline & diesel range organics (GRO/DRO)

Ship & process all samples in one batch to decrease cost.

QC defined per SW 846 [1 MS/MSD, 1 method blank, 1 equipment blank (if equipment is reused), 1 trip blank for GRO only].

Cool GRO/DRO to 4°C, 2°C. QAP written and approved before implementation.

QC and Analysis DetailsUsed in All Approaches

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End of Module 20

Thank you

Questions?

1 of 39 The EPA 7-Step DQO Process Step 7 - Optimize Sample Design DQO Case Study 45 minutes Presenter: Sebastian Tindall DQO Training Course Day 3 Module.

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