1. Kassidy Klink
January 21, 2016
Compliance Averaging Options:
Spatially Weighted Average

2. Arithmetic Mean 95 percent Upper Confidence Limit
Spatially Weighted Average 75 percent/10x Procedure
Compliance Averaging
Options for Ingestion-
Dermal, Inhalation, and
Impact to Ground Water
Pathways (Appendix A)

3.  Applicability
o RI and RA phases
o All exposure pathways
o Single point, horizontal and vertical delineation compliance
necessary
 Definition
o Sampling results are weighted according to the area they
represent
o The corresponding area defined by Thiessen Polygons
• polygons whose boundaries define the area that is closest to each
point relative to all other points
• they are mathematically defined by the perpendicular bisectors of
the lines between all points

5. Notes
• Important to
georeference points
• Use NJDEP sources
(MrSID)
• Replace ND with RL
value

6.  Horizontal Limitations (A2.1.1)
o 0.25/0.5 acres (residential – Inhalation/Ingestion-Dermal) and 2
acres (commercial/industrial)
• Inhalation & Ingestion-Dermal: May be increased by up to 50% if > 1
functional area & contamination cannot be divided evenly
o IGW – must be 100ˈ parallel to ground water flow direction.
Unlimited perpendicular to flow
• Can combine multiple AOCs (including gaps) if <100ˈ
• If >100ˈ: either must use multiple functional areas (default DAF), or
use entire delineated AOC as area (site-specific DAF and IGW
standard must be calculated)
 Bias towards worst case fit

7.  Shape Limitations (A2.1.2)
o Inhalation & Ingestion-Dermal
• Square = preferred shape
• Length of shape can be no more than 4X
width
o IGW
• Must be 100ˈ in length parallel to ground water flow
• Unlimited size perpendicular to ground water flow

8.  Vertical limitations (A2.1.3)
o Inhalation & Ingestion-Dermal
o IGW
o Note: Only analyze zones that have concentrations > standard

10.  Note: If area weighted
mean < standard, then no
further action is
necessary.

11.  Replace your most contaminated polygon with fill or background
concentration until area weighted mean < standard.
 Unrestricted use = remediate removed polygons to fill/background.
Restricted use = subject to institutional/engineering controls + RAP.

12.  Easy way to determine area weighted mean
 Potential to reduce the area to be remediated
 Provides a clear path forward for a client
 Applicable to all pathways