Department of Health Seal

TGM for the Implementation of the Hawai'i State Contingency Plan
Section 4
CONTENTS

SECTION 4 CONTENTS

Acronyms and Abbreviations
 
4.0 Characterization of Decision Units
 
4.1 Sampling Theory and Variability of Contaminant Concentrations in Soil
  4.1.1 Large-Scale and Small-Scale Variability
  4.1.2 Implications of Random, Small-Scale Variability
  4.1.3 Use of Sampling Theory and Multi Increment Sampling to Improve Sample Representativeness
 
4.2 Use of Multi increment Samples to Characterize DUs
  4.2.1 Multi Increment Sampling Methodology
  4.2.2 Minimum Number of Increments
  4.2.3 Target Multi Increment Sample Mass
  4.2.4 Increment Distribution
    4.2.4.1 Systematic Random Grids
  4.2.5 Sample Collection
    4.2.5.1 Locating Increment Collection Points
    4.2.5.2 Increment and Bulk Sample Collection
  4.2.6 Laboratory Preparation of Samples
    4.2.6.1 Sample Processing
    4.2.6.2 Subsample Collection
    4.2.6.3 Particle Size Reduction
    4.2.6.4 Semi-Volatile and Unstable Chemicals
    4.2.6.5 Bioaccessible Arsenic
    4.2.6.6 Other Laboratory Issues
  4.2.7 Replicate Samples
    4.2.7.1 Field Replicate Samples
    4.2.7.2 Laboratory Replicate Samples
    4.2.7.3 Evaluation of Data Representativeness
  4.2.8 Other Considerations
    4.2.8.1 Multi Increment Soil Sample Collection for Volatile Analyses
    4.2.8.2 Collection of Subsurface Multi Increment Samples
    4.2.8.3 Collection of Multi Increment Samples for Stockpiles
 
4.3 Use of Discrete Samples
  4.3.1 Interpretation and Presentation of Isocontour Maps
  4.3.2 Designation of Decision Units
  4.3.3 Estimation of Mean Contaminant Concentrations in Risk Assessments
 
4.4 Common DU-MIS Investigation Mistakes and Problems
  4.4.1 Inappropriately Sized DUs
  4.4.2 Data Gaps Between Surface DUs or Subsurface DU Layers
  4.4.3 Inadequate Number of Increments
  4.4.4 Improper Increment Spacing
  4.4.5 Improper Increment Shape
  4.4.6 Co-located Discrete Samples and Increment Splits
  4.4.7 Inadequate Laboratory Processing
  4.4.8 Inadequate Subsample Mass for Analysis
  4.4.9 Lack of Replicate Sample Data
  4.4.10 Reversion to Discrete Sampling
  4.4.11 DU-MIS Investigations Under TSCA
 
References
 
Figures
  4-1 Variability of Mean Contaminant Concentration within Progressively Smaller Areas and Volumes of Soil within an Initially Designated DU
  4-2 Mass of Soil Typically Tested by a Laboratory
  4-3 Study Site C in 2014 HDOH Field Investigation of Discrete Sample Variability
  4-4 Example "Inter-Sample" Variability of PCB Concentrations in Soil
  4-5 Example "Intra-Sample" Variability of PCB Concentrations in Soil
  4-6 Photomicrograph of Possible PCB-Infused Nugget of Silty Soil
  4-7 Arsenic-Infused Nuggets of Iron-Hydroxide in Volcanic Soil
  4-8 Example Decision Units (a and b)
  4-9 Example Increment Collection Locations Based on a Systematic Random Grid Scheme
  4-10 Examples of Simple Random (a) and Stratified Random (b) Increment Location Patterns and Collection of Closely Spaced Increments from More Widely Spaced Rows (c)
  4-11 Systematic Increment Locations for Odd Shaped DUs
  4-12 Example Collection of Increment Location Points for Triplicate MI Samples
  4-13 Example Flag Placement for Collection of Increments in the Field
  4-14 Collection of Increments in a Long, Narrow DU
  4-15 MI Sample Increment Collection
  4-16 Core-shaped Versus Wedge-shaped Increments
  4-17 Increments Combined to Generate 1-2 kg, Bulk Multi Increment Sample
  4-18 Use of a Sectorial Splitter to Collect Subsamples
  4-19 Manual Collection of Subsamples in the Laboratory
  4-20 Puck and ring mill, used to crush small masses of soil to very fine grain size
  4-21 Ball mill with ceramic cylinders used for moderate crushing of large soil volumes
  4-22 Example Pattern of Increment Collection for Triplicate MI Samples
  4-23 DU Layer Replicates Collected from Separate Sets of Cores to Test Precision of Data with Respect to Distributional Heterogeneity
  4-24 Collection of Increment Subsample Replicates (Triplicates) from Core Increments
  4-25 Collection of large-mass discrete soil samples from multiple locations around a single sampling point in order to improve data representativeness
  4-26 Unadjusted Isoconcentration Map Generated from Discrete Sample Arsenic Data at Nine-Acre, Former Sugar Mill Facility
  4-27 Adjusted Arsenic Isoconcentration Map
  4-28 Example DUs Designated for Former Sugar Mill Facility
  4-29 Four Possible Relationships between Bias and Precision
  4-30 Limited “Compositing” and “Dilution” Allowed Under TSCA to Reduce Laboratory Costs
  4-31 Theoretical Compositing of Multi Increment samples
 
Tables
  4-1 Approximate Increment Spacing for Decision Unit Area (see Equation 1)
  4-2 Recommended Adjustment of Multi Increment Data for Decision Making Based on Relative Standard Deviation (RSD) of Replicate Samples
 
Appendix
  4-A Recommendations for MIS Field Preservation or Laboratory Subsampling Based on Overall Chemical Stability