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Itm 3b_South Y PCE Jun 18 2019 TAC 5_DRIFinal Alternatives Modeling Desert Research Institute Susie Rybarski Mark Hausner TAC Meeting 5 South Y Feasibility Study of Remedial Alternatives (D1712508-1) 6/21/19 PCE Model Recalibration Changes from previous model versions •Adjusted screened interval at LBWC 4 •Added expanded clay lens acting as low vertical conductivity zone •Decreased longitudinal dispersivity to 40m •Increased vertical dispersivity ratio to 0.015 •Increased transverse dispersivity ratio to 0.6 in layers 1 and 2 •Increased decay half-life to 17 years in layers 1 and 2 •Decreased source term by 30% during years LTLW is in operation Calibration Results 0 50 100 150 200 250 1971 1977 1982 1988 1993 1999 2004 2010 2015PCE (ug/l) Clement Simulated Observed 0 50 100 150 200 250 300 1971 1977 1982 1988 1993 1999 2004 2010 2015PCE (ug/l) Rockwater Simulated Observed 0 50 100 150 200 250 1971 1977 1982 1988 1993 1999 2004 2010 2015PCE (ug/l) LBWC 4 Simulated Observed Calibration Results 0 10 20 30 40 50 60 70 80 1971 1977 1982 1988 1993 1999 2004 2010 2015PCE (ug/l) LBWC 5 Simulated Observed 0 5 10 15 20 25 30 1971 1977 1982 1988 1993 1999 2004 2010 2015PCE (ug/l) TKWC 2 Simulated Observed 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 1971 1977 1982 1988 1993 1999 2004 2010 2015PCE (ug/l) TKWC 1 Simulated Observed 2018 stress period, layer 1 2018 stress period, layer 2 2018 stress period, layer 3 Scenario 1A clay lens, 2038 stress period, layer 2 2018 stress period, layer 4 Final Alternatives Modeling Simulated Alternatives Alternative Description Pumping Rates (m3/d) LBWC 1 LBWC 5 TKWC 1 TKWC 2 TKWC 3 Sunset Paloma Helen 2 Bayview Al Tahoe 2 1A Baseline 872.19 199.66 532.54 1219.49 1316.98 1735.79 195.74 713.22 8997.45 1462.21 1B Conservative Baseline** 872.19 199.66 532.54 1219.49 1316.98 1735.79 195.74 713.22 8997.45 1462.21 2A Targeted 199.66 872.19 532.54 1316.98 1219.49 1735.79 195.74 713.22 8997.45 1462.21 2B Conservative Targeted** 199.66 872.19 532.54 1316.98 1219.49 1735.79 195.74 713.22 8997.45 1462.21 3A SW Conversion 872.19 199.66 532.54 1219.49 1316.98 1735.79 195.74 713.22 8997.45 1462.21 3B Conservative SW Conversion** 872.19 199.66 532.54 1219.49 1316.98 1735.79 195.74 713.22 8997.45 1462.21 4 90% GAC Capacity 389.52 3434.13 1458.14 2698.24 808.56 1165.41 131.57 478.85 6039.43 981.75 5 90% Well Capacity 389.52 3434.13 1458.14 8830.61 808.56 353.01 39.85 145.05 1829.36 297.38 ** Conservative simulations include a ‘constant bleed’ recharge concentration and no biogenic decay Alternative 1A: Baseline 0 1 2 3 4 5 6 1971 1985 1999 2012 2026 2040 2053 2067PCE (ug/l) TKWC 1 MCL Detection Limit 0 2 4 6 8 10 12 14 16 1971 1985 1999 2012 2026 2040 2053 2067PCE (ug/l) TKWC 2 MCL Detection Limit 0 5 10 15 20 25 1971 1985 1999 2012 2026 2040 2053 2067PCE (ug/l) LBWC 5 MCL Scenario 1A, 2068 stress period, layer 1 Mass Extracted from L1: 6 kg Scenario 1A clay lens, 2068 stress period, layer 2 Mass Extracted from L2: 146 kg Alternative 1B: Baseline Conservative 0 10 20 30 40 50 60 1971 1985 1999 2012 2026 2040 2053 2067PCE (ug/l) TKWC 1 Alternative 1A - Base Treatment Alternative 1B - Base Treatment (Conservative) MCL 0 20 40 60 80 100 120 1971 1985 1999 2012 2026 2040 2053 2067PCE (ug/l) TKWC 2 Alternative 1A - Base Treatment Alternative 1B - Base Treatment (Conservative) MCL 0 20 40 60 80 100 120 1971 1985 1999 2012 2026 2040 2053 2067PCE (ug/l) LBWC 5 Alternative 1A - Base Treatment Alternative 1B - Base Treatment (Conservative) MCL Scenario 1B, 2068 stress period, layer 1 Mass Extracted from L1: 58 kg Scenario 1B, 2068 stress period, layer 2 Mass Extracted from L2: 906 kg Scenario 1B, 2068 stress period, layer 3 Mass Extracted from L3: 155 kg Scenario 1B, 2068 stress period, layer 4 Alternative 2A: Targeted Pumping 0 2 4 6 8 10 12 14 16 1971 1985 1999 2012 2026 2040 2053 2067PCE (ug/l) TKWC 2 Alternative 2A - Targeted Pumping Alternative 1A - Base Treatment MCL Detection Limit 0 1 2 3 4 5 6 1971 1985 1999 2012 2026 2040 2053 2067PCE (ug/l) TKWC 1 Alternative 2A - Targeted Pumping Alternative 1A - Base Treatment Detection Limit MCL 0 5 10 15 20 25 1971 1985 1999 2012 2026 2040 2053 2067PCE (ug/l) LBWC 5 Alternative 2A - Targeted Pumping Alternative 1A - Base Treatment MCL Scenario 2A, 2068 stress period, layer 1 Mass Extracted from L1: 6 kg Scenario 2A, 2068 stress period, layer 2 Mass Extracted from L2: 238 kg Alternative 2B: Targeted Pumping Conservative 0 20 40 60 80 100 120 1971 1985 1999 2012 2026 2040 2053 2067PCE (ug/l) TKWC 2 Alternative 2A Alternative 2B Alternative 1B MCL 0 10 20 30 40 50 60 1971 1985 1999 2012 2026 2040 2053 2067PCE (ug/l) TKWC 1 Alternative 2A Alternative 2B Alternative 1B MCL 0 20 40 60 80 100 1971 1985 1999 2012 2026 2040 2053 2067PCE (ug/l) LBWC 5 Alternative 2A Alternative 2B Alternative 1B MCL Scenario 2B, 2068 stress period, layer 1 Mass Extracted from L1: 53 kg Scenario 2B, 2068 stress period, layer 2 Mass Extracted from L2: 1314 kg Scenario 2B, 2068 stress period, layer 3 Mass Extracted from L3: 213 kg Scenario 2B, 2068 stress period, layer 4 Alternative 3A: SW Conversion 0 1 2 3 4 5 6 1971 1978 1985 1992 1999 2005 2012 2019 2026 2033PCE (ug/l) TKWC 1 MCL Detection Limit 0 2 4 6 8 10 12 14 1971 1978 1985 1992 1999 2005 2012 2019 2026 2033PCE (ug/l) TKWC 2 MCL Detection Limit 0 5 10 15 20 25 1971 1978 1985 1992 1999 2005 2012 2019 2026 2033PCE (ug/l) LBWC 5 MCL Scenario 3A, 2033 stress period, layer 1 Mass Extracted from L1: 2 kg Scenario 3A, 2033 stress period, layer 2 Mass Extracted from L2: 100 kg Scenario 3A, 2033 stress period, layer 3 Mass Extracted from L3: 3 kg Alternative 3B: SW Conversion Conservative 0 10 20 30 40 50 60 1971 1978 1985 1992 1999 2005 2012 2019 2026 2033PCE (ug/l) TKWC 1 Alternative 3A - SW Conversion Alternative 3B - SW Conversion (Conservative) MCL 0 20 40 60 80 100 120 1971 1978 1985 1992 1999 2005 2012 2019 2026 2033PCE (ug/l) TKWC 2 Alternative 3A - SW Conversion Alternative 3B - SW Conversion (Conservative) MCL 0 20 40 60 80 100 120 1971 1978 1985 1992 1999 2005 2012 2019 2026 2033PCE (ug/l) LBWC 5 Alternative 3A - SW Conversion Alternative 3B - SW Conversion (Conservative) MCL Scenario 3B, 2033 stress period, layer 1 Mass Extracted from L1: 14 kg Scenario 3B, 2033 stress period, layer 2 Mass Extracted from L2: 512 kg Scenario 3B, 2033 stress period, layer 3 Mass Extracted from L3: 155 kg Scenario 3B, 2033 stress period, layer 4 Alternative 4: 90% GAC Capacity 0 1 2 3 4 5 6 1971 1985 1999 2012 2026 2040 2053 2067PCE (ug/l) TKWC 1 Alternative 4 - 90% GAC Capacity Alternative 1A - Base Treatment Detection Limit MCL 0 2 4 6 8 10 12 14 1971 1985 1999 2012 2026 2040 2053 2067PCE (ug/l) TKWC 2 Alternative 4 - 90% GAC Capacity Alternative 1A - Base Treatment MCL Detection Limit 0 5 10 15 20 25 1971 1985 1999 2012 2026 2040 2053 2067PCE (ug/l) LBWC 5 Alternative 4 - 90% GAC Capacity Alternative 1A - Base Treatment MCL Scenario 4, 2068 stress period, layer 1 Mass Extracted from L1: 7 kg Scenario 4, 2068 stress period, layer 2 Mass Extracted from L2: 463 kg Alternative 5: 90% Well Capacity 0 1 2 3 4 5 6 1971 1985 1999 2012 2026 2040 2053 2067PCE (ug/l) TKWC 1 Alternative 5 - 90% Well Capacity Alternative 1A - Base Treatment Detection Limit MCL 0 2 4 6 8 10 12 14 1971 1985 1999 2012 2026 2040 2053 2067PCE (ug/l) TKWC 2 Alternative 5 - 90% Well Capacity Alternative 1A - Base Treatment MCL Detection Limit 0 5 10 15 20 25 30 1971 1985 1999 2012 2026 2040 2053 2067PCE (ug/l) LBWC 5 Alternative 5 - 90% Well Capacity Alternative 1A - Base Treatment MCL 31 27 12 22 7 102 105 74 113 230 25 93 20 316 284 157 226 105 451 521 0 100 200 300 400 500 600 Alternative 1A Alternative 2A Alternative 3A Alternative 4 Alternative 5Mass Extracted (kg) TKWC 1 TKWC 2 LBWC5 Total Mass Extracted by Well over Model Duration 0 5 10 15 20 25 30 Alternative 1A Alternative 2A Alternative 4 Alternative 5Years to PCE < 4 ug/l TKWC 1 TKWC 2 LBWC5 Years to Clean Up Note: Concentrations never exceed 4 ug/l at TKWC 1 for Alternatives 4 and 5 Questions?