Transcript LDEQ
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 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 B14 18 ppm B2 B16 16 ppm 6 ppm B13 29 ppm B15 15 ppm B7 <0.01 B18 9 ppm B11 18 ppm B10 4 ppm AOI B4 B5 < 0.005 12 ppm B1 55 ppm B3 32 ppm B9 22 ppm B12 <0.005 B6 17 ppm B8 <0.005 B17 <0.005 5 Identification of the AOI LRS = 10 ppm AOI SS AOI PSS B14 6 ppm B16 4 ppm B2 14 ppm B1 33 ppm B13 B7 13 ppm <0.01 B3 12 ppm B11 11 ppm B18 <0.01 B4 <0.01 B5 <0.01 B8 2ppm 3’ bgs 15’ bgs 6 Identification of the AOI Illustrate all sampling locations and AOI Summarize AOI data set 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 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 12 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 13 Identification of the AOI If multiple chemicals present: Identify one AOI that includes all chemicals 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: Identification of an AOI is not possible Options: Evaluate under higher tier If appropriate, re-sample area Remediate impacted area(s) 17 Identification of the AOI Single vs Multiple Considerations: Distance Receptor activity patterns AOI AOI AOI COC 18 Identification of the AOI Multiple AOI and Additivity Considerations: Distance Receptor activity patterns AOI AOI AOI 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 Soil AOI Enclosed Structure •Soili or Soilni •Soilgw •Soilsat • Soiles 21 Identification of the AOI Based on Pathways Enclosed Structure Groundwater AOI GW to ES AOI • GWes • GW1, 2, or 3 • Watersol 22 Identification of the AOI Based on Pathways Enclosed Structure Groundwater AOI • GW1, 2, or 3 • Watersol • GWes 23 Identification of the AOI Based on Pathways Soil-PEF AOI Soil AOI Unpaved Road •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 95% UCL-AM concentration All data points on or within the AOI 29 Identification of the AOI LRS = 10 ppm B14 18 ppm B2 B16 16 ppm 6 ppm B13 29 ppm B15 15 ppm B7 <0.01 B18 9 ppm B11 18 ppm B10 4 ppm AOI B4 < 0.005 B5 12 ppm B1 55 ppm B3 32 ppm B9 22 ppm B12 <0.005 B6 17 ppm B8 <0.005 B17 <0.005 30 Exposure/Source Concentration 95% UCL-AM Dataset for the 95%UCL-AM: B1 B2 B3 B4 B5 B6 55 ppm 16 ppm 32 ppm 0.005 ppm 12 ppm 17 ppm B7 B9 B11 B13 B14 B15 0.01 ppm 22 ppm 18 ppm 29 ppm 18 ppm 15 ppm 31 Exposure/Source Concentration 95% UCL-AM Determine constituent distribution LogNormal* Normal Non-Normal 32 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 33 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 34