LDEQ RECAP 1 RECAP Identification of the Area

LDEQ RECAP 1

RECAP Identification of the Area of Investigation AOI 2

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. 3

Identification of the AOI n n 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 4

Identification of the AOI LRS = 10 ppm B 14 18 ppm B 2 B 16 16 ppm B 13 29 ppm B 15 15 ppm B 7 <0. 01 B 18 9 ppm B 11 18 ppm B 10 4 ppm AOI B 4 B 5 < 0. 005 12 ppm B 1 55 ppm B 3 32 ppm B 9 22 ppm B 12 <0. 005 B 6 17 ppm B 8 <0. 005 B 17 <0. 005 5

Identification of the AOI LRS = 10 ppm AOI SS AOI PSS B 14 6 ppm B 16 4 ppm B 2 14 ppm B 1 33 ppm B 13 B 7 13 ppm <0. 01 B 3 12 ppm B 11 11 ppm B 18 <0. 01 B 4 <0. 01 B 5 <0. 01 B 8 2 ppm 3’ bgs 15’ bgs 6

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

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

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) 9

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) 10

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 11

Identification of the AOI Site-specific Soil. SSi/ni If AOC does not qualify for SO: n Area of impacted soil > 0. 5 acre p all other criteria for SO are met n Develop site-specific Soil. SSi or Soil. SSni p site-specific area of impacted soil p Appendix H 12

Identification of the AOI Site-specific Soil. SSi/ni n Identify limiting SS p site-specific Soil. SSi or Soil. SSni p Table 1 Soil. SSGW n Identify AOI using limiting soil SS n May be re-iterative process 13

Identification of the AOI If multiple chemicals present: n Identify one AOI that includes all chemicals n Identify an AOI for each chemical 14

Identification of the AOI One AOI that includes all COCs: Ex) BTEX B T, X AOI E 15

Identification of the AOI Identification of an AOI for each COC: Ex) BTEX AOI for B AOI for T, X AOI for E 16

Identification of the AOI If only 1 or 2 sampling locations > SS or LRS: n Identification of an AOI is not possible n Options: p Evaluate under higher tier p If appropriate, re-sample area p Remediate impacted area(s) 17

Identification of the AOI Single vs Multiple I O A Considerations: n Distance n Receptor activity patterns AOI AOI n COC 18

Identification of the AOI Multiple AOI and Additivity I O A Considerations: n Distance n Receptor activity patterns AOI AOI n COC 19

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

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

Identification of the AOI Based on Pathways Enclosed Structure Groundwater AOI GW to ES AOI • GWes • GW 1, 2, or 3 • Watersol 22

Identification of the AOI Based on Pathways Enclosed Structure Groundwater AOI • GW 1, 2, or 3 • Watersol • GWes 23

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

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

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

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

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

Exposure/Source Concentration 95% UCL-AM concentration p All data points on or within the AOI 29

Identification of the AOI LRS = 10 ppm B 14 18 ppm B 2 B 16 16 ppm B 13 29 ppm B 15 15 ppm B 7 <0. 01 B 18 9 ppm B 11 18 ppm B 10 4 ppm AOI B 4 < 0. 005 B 5 12 ppm B 1 55 ppm B 3 32 ppm B 9 22 ppm B 12 <0. 005 B 6 17 ppm B 8 <0. 005 B 17 <0. 005 30

Exposure/Source Concentration 95% UCL-AM Dataset for the 95%UCL-AM: B 1 55 ppm B 7 0. 01 ppm B 2 16 ppm B 9 22 ppm B 3 32 ppm B 11 18 ppm B 4 0. 005 ppm B 13 29 ppm B 5 12 ppm B 14 18 ppm B 6 17 ppm B 15 15 ppm 31

Exposure/Source Concentration 95% UCL-AM n Determine constituent distribution p Log. Normal* p Normal p Non-Normal 32

Exposure/Source Concentration 95% UCL-AM n Use methods consistent with RECAP p Supplemental Guidance to RAGS: Calculating the Concentration Term (EPA 1992) p Statistical Methods for Environmental Pollution Monitoring (Gilbert 1987) p Log. Normal distribution: H-Statistic p Normal distribution: Student-t Statistic 33

Exposure/Source Concentration 95% UCL-AM n Identify data points used to calculate 95%UCL-AM n Present statistical calculations/spreadsheets n Limited data set or high variability n Maximum detected value 34