Incremental SamplingCase Studies

November 6, 2014

INTRODUCTION

• What is Incremental Sampling (IS)?

• A method that reduces sampling error

• A method that reduces lab error

• A method that provides an accurate average concentration for any constituent in any area

INTRODUCTION

Data Quality Objective (DQO) Process

Step 1: State Problem Step 2: Identify Decision

Step 3: Identify Decision Inputs Step 4: Define Study Boundaries Step 5: Develop Decision Rules

Step 6: Specify Performance Criteria Step 7: Optimize Design

Why

What

Where

How

Decision Units

What if we sampled differently?

Discrete Sampling

• A single sample

• Representative of a point within an area

Incremental Sampling

• A single sample

• Multiple increments

• Representative of an area

Discrete vs. Incremental

Methodology

• IS methodology is a two-part process

• Part 1: Field Implementation

Collect multiple (50 to 100) increments of uniform size from the entire decision unit

Combine increments into a single 1 to 2 kilogram sample

• Part 2: Laboratory Processing and Analysis

Air drying and sieving entire sample

Particle size reduction (grinding) of entire sample

Increment sub-sampling to provide representative aliquot for extraction and analysis

What does this tell us?

IS sampling covers the entire area of exposure. Replicate samples, three (3) separate IS samples, are collected from a DU.

Original Sample: 9.2 mg/kgDuplicate Sample: 11 mg/kgTriplicate Sample: 8.5 mg/kg

% Relative Standard Deviation = 13.7%(less than 30% demonstrates good precision)

We have confidence that the results:

• Cover the entire exposure at the site.

• Represent the sampled average concentration for each DU.

• Decisions can be made.

IS Methodology is Consistent with Our

Programs

Discrete sampling allows for calculation of the average concentration from multiple samples.

Incremental sampling allows for the measurement of the average concentration from a single sample.

IS Program Applicability 201

213

Superfund

Brownfields

Due Care

Solid Waste

IS Site Applicability Spill areas

Airborne deposition to soils

Historic pesticide uses (orchards)

Shooting ranges

Wetland, stream, river, lake shore sediments

Excavation sidewalls and floors

Soil borings and cores

Utility trenches

Waste Piles

Can be used for all types of contaminants

Sites Completed Using IS Mueller Brass Ash Field OLF Four Former

Orchards Roy Smothers TCIW Lay Park Marathon Site Iron Mountain Terrace Point Drew Ripple Total Marine Terminal Ford Wixom Plant Milwaukee Junction Fordson Island

Kalamazoo River Harbor Heights Orchard View Ralph Herman Farm Holly Road The Mines Golf Course Camp Norrie

IS Case Studies

Ash Field Outlying Filed (OLF)

Ford Wixom

Mueller

Orchard View

Residential Wells Holly Road

IS Sub-Surface Sampling

RESIDENTIAL WELLS HOLLY ROAD

IS Sub-Surface SamplingPROBLEM

Chlorinated solvents “feeding” the plume.

DECISION

Determine if soil concentrations warrant re-start of the mothballed SVE system and/or reconfiguration of the SVE system.

or

Consider other remedies if indicated by the data.

DECISION UNIT(S)

Areas surrounding the overall footprint of the SVE system. Lithology includes upper and lower sub-units that are 8 feet deep each and end at 16 below ground level (at the water table).

IS Sub-Surface SamplingDECISION RULE

Results must indicate that sufficient mass of contaminants exceeding drinking water protection criteria to re-start and/or reconfigure the SVE unit.

If not, retire the SVE and consider other remedial options.

ERROR LIMITS

Collect replicate IS samples from 2 of 11 DU’s. Acceptable field sampling error is 30 % RSD.

OPTIMIZE DATA COLLECTION

Consider site history, source areas soil data, SVE system design…

IS Sub-Surface Sampling

IS Sub-Surface SamplingSAMPLING METHOD

4 foot macro-cores collected via direct push. 2 cores for each boring in a DU subset. Each DU subset (A and B) is 8 foot thick. Total depth of the DU is 16 feet (just above the water table).

The number of borings in the DU are divided to determine the number of increments per core. 50 plugs per DU sub-set.

10 grams of soil per plug. 50 increments per DU subset will provide a 1:1 ratio for 500 ml of methanol in an amber bottle.

5 grams of solids are weighed per increment.

IS Sub-Surface Sampling

IS Sub-Surface SamplingIS SAMPLING RESULTS

DU Sub-Units 1A, 2A, 3A and B, 4A, 5A and B, 6A and B, 8A, 9A, 10 A and B, 11 A and B are below part 201 groundwater protection (GWP) criteria for TCE (100 kg/mg).

DU Sub-Units 2B, 7A and 8B are one to two times GWP criteria for TCE.

DU Sub-Units 1B, 4B, 7B and 9B exceed GWP criteria by 3 to 17 times.

The remedy must address the deeper soils in DU’s 1, 4, 7 and 9; lesser emphasis in deep soils of DU’s 2 and 8 and shallow soils in DU 7A.

IS Sub-Surface SamplingREPLICATE RESULTS

DU-7A:Shallow soils in the former drum storage area. Average TCE concentration is 157 ug/kg.

RSD = 21% (acceptable).

DU-7B: Deeper soils, drum storage area. Average TCE concentration is 378 ug/kg.

RSD = 10.2% (acceptable).

DU-9A : Shallow soils in the loading area. Average TCE concentration is 318 ug/kg. RSD = 9.74 (acceptable).

DU-9B: Deeper soils in the loading area. Average TCE concentration is 407 ug/kg.

RSD = 21.2 (acceptable).

IS Sub-Surface SamplingPROJEC T SCHEDULE AND COSTS

3.5 days of fieldwork completed 11 DU’s comprising of 2 DU subsets equal to 22 sets of VOC incremental samples. 22 VOC incremental samples plus 6 QA/QC replicates and 4 matrix spikes. The 11 DU’s included a total of 30 sixteen (16) foot borings by earth probe.

Soil samples logged for lithology. Better lithology detail is noticed as the IS samples are collected.

Analytical costs a little more than 5K.

Project costs similar to discrete sampling in this case.

IS Sub-Surface SamplingCONCLUSIONS

IS provided missing information relating to TCE contaminant mass present in the soils subject to SVE remediation.

IS provided a higher level of certainty and better estimates of contaminant mass when compared with discrete (VSR) soil sampling.

Evaluation of all of the site information determined that redesign of the SVE unit by adding two lines and retiring 4 of 11 SVE wells appears to be the most cost-effective and practical option to treat remaining source soils.

Contact Information

JOSEPH DEGRAZIA

Department of Environmental Quality

Southeast Michigan District Office

o: (586) 753-3812

c: (586) 921-0476

degraziaj@michigan.gov