1. LDEQ
RECAP

2. Identification of the Area of Investigation
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 > limiting standard
Define the horizontal and vertical boundaries of AOI

5. Identification of the AOI LRS = 10 ppm
B15
15 ppm
B14
18 ppm B4
< 0.005
AOI B5
12 ppm B2
16 ppm
B16
6 ppm B1
55 ppm
B12
<0.005
B13
29 ppm B6
17 ppm B7
<0.01 B3
32 ppm
B11
18 ppm B8
<0.005
B18
9 ppm B9
22 ppm
B10
4 ppm
B17
<0.005

6. Identification of the AOI LRS = 10 ppmB4
<0.01
AOI SS B2
14 ppm
B14
6 ppm B1
33 ppm B5
<0.01
3’ bgs
AOI
PSS
B16
4 ppm
B13
13 ppm B7
<0.01 B3
12 ppm
B11
11 ppm B8
2ppm
15’ bgs
B18
<0.01

7. Identification of the AOI
Illustrate all sampling locations and AOI
Summarize AOI data set
All impacted media

8. Identification of the AOI Tiered Approach
SO: Identify all sampling locations > SS
Area > SS
AOI for MO-1
If all locations < SS  NFA

9. Identification of the AOI Tiered Approach
MO-1: 1) AOI defined by locations > SS
2) Determine E/SC for AOI
3) Compare to MO-1 LRS, if < LRS  NFA
4) If E/SC > LRS  Id AOI for MO-2
MO-1 AOI
(Area > SS)
MO-2 AOI
(Area > MO-1 RS)

10. Identification of the AOI Tiered Approach
MO-2: 1) AOI defined by locations > MO-1 LRS
2) Determine E/SC for AOI
3) Compare to MO-2 LRS; if < LRS  NFA
4) If E/SC > LRS  Id AOI for MO-3
MO-2 AOI
(Area > MO-1 RS)
MO-3 AOI
(Area > MO-2 RS)

11. Identification of the AOI Tiered Approach
MO-3: 1) AOI defined by locations > MO-2 LRS
2) Determine E/SC for AOI
3) Compare to MO-3 LRS, if < LRS  NFA
4) If E/SC > LRS  Id area to be remediated
MO-3 AOI
(Area > MO-2 RS)
Remediate
Area > MO-3 RS

12. Identification of the AOI Site-specific SoilSSi/ni
If AOC does not qualify for SO:
Area of impacted soil > 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 > 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 AOI Single vs Multiple
Considerations:
Distance
Receptor activity patterns
COC
AOI
AOI

19. Identification of the AOI Multiple AOI and Additivity
Considerations:
Distance
Receptor activity patterns
COC
AOI
AOI

20. Identification of the AOI Based on Pathways
Enclosed
Structure
Soil AOI
Soili or Soilni
Soilgw
Soilsat
Soil to ES AOI
Soiles

21. Identification of the AOI Based on Pathways
Soil AOI
Soili or Soilni
Soilgw
Soilsat
Soiles
Enclosed
Structure

22. Identification of the AOI Based on Pathways
Enclosed
Structure
Groundwater AOI
GW to ES AOI
GW1, 2, or 3
Watersol
GWes

23. Identification of the AOI Based on Pathways
Groundwater AOI
GW1, 2, or 3
Watersol
GWes
Enclosed
Structure

24. Identification of the AOI Based on Pathways
Soil-PEF
AOI
Soil AOI
Soili or Soilni
Soilgw
Soilsat
Unpaved
Road

25. Identification of the AOI Based on Pathways
Soil-PEF AOI
Soili-PEF or Soilni- PEF
Soilgw
Soilsat

26. Identification of the AOI Based on Land Use
Residential
AOI
Soilni
(Soilgw)
(Soilsat)
Industrial Soil AOI
Soili
Soilgw
Soilsat
Industrial property
boundary

27. Identification of the AOI Based on COC
AOI for COC #1
AOI for
COC #2

28. Identification of the AOI Remediation Verification
Post-Remediation
AOI
Area Identified for
Remediation
(Area > LRS)

29. Exposure/Source Concentration 95% 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
< 0.005
AOI B5
12 ppm B2
16 ppm
B16
6 ppm B1
55 ppm
B12
<0.005
B13
29 ppm B6
17 ppm B7
<0.01 B3
32 ppm
B11
18 ppm B8
<0.005
B18
9 ppm B9
22 ppm
B10
4 ppm
B17
<0.005

31. Exposure/Source Concentration 95% UCL-AM
Dataset for the 95%UCL-AM:
B ppm B ppm
B ppm B ppm
B ppm B ppm
B ppm B ppm
B ppm B ppm
B ppm B ppm

32. Exposure/Source Concentration 95% 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 95%UCL-AM
Present statistical calculations/spreadsheets
Limited data set or high variability
Maximum detected value