LDEQ

1
LDEQ

• RECAP

2
RECAP

• Identification of the Area of Investigation
• ? AOI ?

3
RECAP

• The AOI is the zone contiguous to, and including,
  impacted media defined vertically and
  horizontally by the presence of one or more
  constituents in concentrations that exceed the
  limiting standard applicable for the option being
  implemented.

4
Identification of the AOI

• Identify limiting standard for option
• Compare limiting standard to concentration
  detected at each sampling location
• Identify each location where the concentration gt
  limiting standard
• Define the horizontal and vertical boundaries of
  AOI

5
Identification of the AOI LRS 10 ppm
B15 15 ppm
B4 lt 0.005
B14 18 ppm
AOI
B5 12 ppm
B2 16 ppm
B16 6 ppm
B1 55 ppm
B12 lt0.005
B13 29 ppm
B6 17 ppm
B7 lt0.01
B3 32 ppm
B11 18 ppm
B8 lt0.005
B9 22 ppm
B18 9 ppm
B10 4 ppm
B17 lt0.005
6
Identification of the AOI LRS 10 ppm
B4 lt0.01
B2 14 ppm
AOI SS
B1 33 ppm
B14 6 ppm
B5 lt0.01
3 bgs
AOI PSS
B13 13 ppm
B16 4 ppm
B7 lt0.01
B3 12 ppm
B11 11 ppm
B8 2ppm
15 bgs
B18 lt0.01
7
Identification of the AOI

• Illustrate all sampling locations and AOI
• Summarize AOI data set
• All impacted media

8
Identification of the AOITiered Approach

SO Identify all sampling locations gt SS
Area gt SS
AOI for MO-1
If all locations lt SS ? NFA
9
Identification of the AOITiered Approach
MO-1 1) AOI defined by locations gt SS 2)
Determine E/SC for AOI 3) Compare to MO-1 LRS,
if lt LRS ? NFA 4) If E/SC gt LRS ? Id AOI for
MO-2

MO-1 AOI (Area gt SS)
MO-2 AOI (Area gt MO-1 RS)
10
Identification of the AOITiered Approach

MO-2 1) AOI defined by locations gt MO-1 LRS
2) Determine E/SC for AOI 3) Compare to MO-2
LRS if lt LRS ? NFA 4) If E/SC gt LRS ? Id AOI
for MO-3
MO-2 AOI (Area gt MO-1 RS)
MO-3 AOI (Area gt MO-2 RS)
11
Identification of the AOITiered Approach

MO-3 1) AOI defined by locations gt MO-2 LRS
2) Determine E/SC for AOI 3) Compare to
MO-3 LRS, if lt LRS ? NFA 4) If E/SC gt LRS ? Id
area to be remediated
MO-3 AOI (Area gt MO-2 RS)
Remediate Area gt MO-3 RS
12
Identification of the AOISite-specific
SoilSSi/ni

• If AOC does not qualify for SO
• Area of impacted soil gt 0.5 acre
• all other criteria for SO are met
• Develop site-specific SoilSSi or SoilSSni
• site-specific area of impacted soil
• Appendix H

13
Identification of the AOI Site-specific
SoilSSi/ni

• Identify limiting SS
• site-specific SoilSSi or SoilSSni
• Table 1 SoilSSGW
• Identify AOI using limiting soil SS
• May be re-iterative process

14
Identification of the AOI

• If multiple chemicals present
• Identify one AOI that includes all chemicals
• Identify an AOI for each chemical

15
Identification of the AOI

• One AOI that includes all COCs
• Ex) BTEX

B
T, X
AOI
E
16
Identification of the AOI

• Identification of an AOI for each COC
• Ex) BTEX

AOI for B
AOI for T, X
AOI for E
17
Identification of the AOI

• If only 1 or 2 sampling locations gt SS or LRS
• Identification of an AOI is not possible
• Options
• Evaluate under higher tier
• If appropriate, re-sample area
• Remediate impacted area(s)

18
Identification of the AOISingle vs Multiple
AOI
AOI

• Considerations
• Distance
• Receptor activity patterns
• COC

AOI
AOI
19
Identification of the AOIMultiple AOI and
Additivity
AOI
AOI

• Considerations
• Distance
• Receptor activity patterns
• COC

AOI
AOI
20
Identification of the AOIBased on Pathways
Enclosed Structure
Soil AOI

• Soili or Soilni
• Soilgw
• Soilsat

Soil to ES AOI

• Soiles

21
Identification of the AOIBased on Pathways
Soil AOI

• Soili or Soilni
• Soilgw
• Soilsat

• Soiles

Enclosed Structure
22
Identification of the AOIBased on Pathways
Enclosed Structure
Groundwater AOI

• GW1, 2, or 3
• Watersol

GW to ES AOI

• GWes

23
Identification of the AOIBased on Pathways
Groundwater AOI

• GW1, 2, or 3
• Watersol
• GWes

Enclosed Structure
24
Identification of the AOIBased on Pathways
Soil-PEF AOI
Soil AOI

• Soili or Soilni
• Soilgw
• Soilsat

Unpaved Road
25
Identification of the AOIBased on Pathways
Soil-PEF AOI

• Soili-PEF or Soilni- PEF
• Soilgw
• Soilsat

26
Identification of the AOIBased on Land Use
Residential AOI

• Soilni
• (Soilgw)
• (Soilsat)

Industrial Soil AOI

• Soili
• Soilgw
• Soilsat

Industrial property boundary
27
Identification of the AOIBased on COC
AOI for COC 1
AOI for COC 2
28
Identification of the AOIRemediation Verification
Post-Remediation AOI
Area Identified for Remediation (Area gt LRS)
29
Exposure/Source Concentration95 UCL-AM

• 95 UCL-AM concentration
• All data points on or within the AOI

30
Identification of the AOI LRS 10 ppm
B15 15 ppm
B14 18 ppm
B4 lt 0.005
AOI
B5 12 ppm
B2 16 ppm
B16 6 ppm
B1 55 ppm
B12 lt0.005
B13 29 ppm
B6 17 ppm
B7 lt0.01
B3 32 ppm
B11 18 ppm
B8 lt0.005
B9 22 ppm
B18 9 ppm
B10 4 ppm
B17 lt0.005
31
Exposure/Source Concentration 95 UCL-AM

• Dataset for the 95UCL-AM
• B1 55 ppm B7 0.01 ppm
• B2 16 ppm B9 22 ppm
• B3 32 ppm B11 18 ppm
• B4 0.005 ppm B13 29 ppm
• B5 12 ppm B14 18 ppm
• B6 17 ppm B15 15 ppm

32
Exposure/Source Concentration95 UCL-AM

• Determine constituent distribution
• LogNormal
• Normal
• Non-Normal

33
Exposure/Source Concentration 95 UCL-AM

• Use methods consistent with RECAP
• Supplemental Guidance to RAGS Calculating the
  Concentration Term (EPA 1992)
• Statistical Methods for Environmental Pollution
  Monitoring (Gilbert 1987)
• LogNormal distribution H-Statistic
• Normal distribution Student-t Statistic

34
Exposure/Source Concentration 95 UCL-AM

• Identify data points used to calculate 95UCL-AM
• Present statistical calculations/spreadsheets
• Limited data set or high variability
• Maximum detected value