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Agenda_17W006_ TAC Proj Mtng 3 Materials_20181023AGENDA SOUTH TAHOE PUBLIC UTILITY DISTRICT TAC Meeting 3 South YFeasibility Study of Remedial Alternatives(D1712508) Tuesday, October 23, 2018 9:30 AM- 12:00 PM Go To Meeting Conference Call Call-In Number: +1 (872) 240-3412; Access Code: 794-898-717 X:\Projects\General\17W006_So Y FS\4.0 TAC\Mtng 3_Oct 2018\Agenda_7W006_ TAC Proj Mtng 3_20181023.docx 1 1) Welcome/Self Introductions 9:30 2) Items in Progress 9:40 a) MOU Update (T. Carter) b) Baseline Human Health Risk Assessment (KJC) c) FS Work Plan (KJC) d) PDI Draft Report (KJC) 3) Remedial Action Objectives (KJC) 10:00 a) Remedial Action Objectives 4) Remedial Scenario Definition (KJC) 10:45 a) Well Head Treatment b) Replacement Wells c) Mid-Plume Remediation • PCE Distribution • 2016 – 2018 Field Data • Model Simulated Contours d) TAC Discussion/Remedial Scenarios for Model Evaluation 5) Upcoming Activities 11:30 a) So. Y Groundwater Level Data Collection b) Public Meeting 3 (11/07/2018-tent.) c) PDI Draft Report Submittal d) Modeling Evaluation/Remedial Scenarios e) FS - Screen Modeled Alternatives f) FS – Select and Develop Recommended Alternative 6) Adjourn 12:00 AGENDA SOUTH TAHOE PUBLIC UTILITY DISTRICT TAC Meeting 3 South YFeasibility Study of Remedial Alternatives(D1712508) Tuesday, October 23, 2018 9:30 AM- 12:00 PM Go To Meeting Conference Call Call-In Number: +1 (872) 240-3412; Access Code: 794-898-717 X:\Projects\General\17W006_So Y FS\4.0 TAC\Mtng 3_Oct 2018\Agenda_7W006_ TAC Proj Mtng 3_20181023.docx 2 ATTACMENT A Remedial Action Objective (RAO) Handouts • FS Workplan – RAO Objectives Table (draft) • Table 1 Basin Remedial Action Objectives (draft) • Table 2 Interim Remedial Action Objectives (draft)  Feasibility Study Workplan RAO Objectives Table Line No General EPA Remedial Action Objectives South Y Specific Remedial Action Objectives Comments  Source: Per EPA Document 540/R‐96/023: Objectives applicable for all sites with contaminated groundwater include the following: 1 Prevent exposure to contaminated ground water, above acceptable risk levels. Allow additional groundwater production without treatment   2 Prevent or minimize further migration of the contaminant plume (plume containment). Design and implement remedies without increasing existing volume of groundwater impacted by HVOCs ( C ) (plume containment)  3 Prevent or minimize further migration of contaminants from source materials to ground water (source control). Concentration reduction to < 50 ppb at drinking water wells, mass removal for proposed remedial measure To avoid 97‐005 permitting requirements 4 Return ground waters to their expected beneficial uses wherever practicable (aquifer restoration). Not applicable for South Y study  Source: Per EPA Document 540/G‐88/003: Remedial Action Objectives for contaminated groundwater sites should address the following: 5 Cleanup Level  Assist in overall objective of supplying water without detectable HVOCs( C) to customers  Comply with regulatory agency requirements and directives regarding HVOCs (C ) in groundwater RAO that aims to reduce contaminant mass to reduce the cleanup burden (e.g., reduce well head treatment duration) for downgradient receptors required to cleanup pumped water to MCLs for distribution and consumption – maybe this amounts to some level of concentration reduction, but still greater than MCLs in in‐situ groundwater. 6 Area of Attainment  Address groundwater within specified area and depth interval  This is addressed above and likely to include the area of the plume between the source zone and the downgradient extent of the plume 7 Restoration Time Frame  Need some sort of time criteria – are water agencies able to continue remediation indefinitely? RAO that acknowledge STPUD’s/Water Agency’s efforts as interim and will be maintained until such time that source control has been implemented by the RPs and groundwater concentrations have declined to influent levels that are equal to or less than the proposed cleanup level above) Other South Y Specific Objectives    Preserve ability to recover HVOC( C) response costs from responsible parties and/or state grant funding in the future    Preference for beneficial use of any extracted groundwater resource (i.e. not disposal to sanitary sewer or storm drain)    Reduce costs (capital or long‐term O&M) for groundwater remedial wellhead treatment to retail customers    Perform community outreach and information activities regarding HVOCs( C) in groundwater  Notes: (a) STPUD is responsible for management of the groundwater basin. Other water supply entities are the water retailers. (b) Other parties have been named as responding parties to a Cleanup and Abatement Order issued by the Water Board. (c) HVOCs = halogenated volatile organic compounds including tetrachloroethene (PCE) and its degradation products.  Commented [SI5]: DFA comment: RAO number five is specific to a cleanup level/objective. Please determine which Proposition 1 metric of success (e.g., contaminant reduction, mass removed, etc.) could l be achieved to satisfy this this RAO. Commented [SI6]: DFA Comment: RAO number six is specific to an area of attainment. Please identify the project area that will be addressed as part of the Project. Commented [SI7]: DFA Comment: RAO number seven is specific to a restoration timeframe. Please identify an estimated timeframe in which the metric of success in RAO number five could be achieved.Commented [SI8]: DFA Comment: Other objectives are listed in the table and can be deleted as they will be satisfied by other tasks identified in the grant agreement and/or as part of implementing the recommended alternative (e.g., preserve ability to recover response costs, preference for beneficial use of any extracted groundwater resource, reduce costs for groundwater remedial wellhead treatment to retail customers, perform community outreach).    Table 1: Basin Remedial Action Objectives -DRAFTPrevent exposure to groundwater containing COCs exceeding acceptable risk levels•Provide an alternate water supply for the population served by existing wells affected by the plume of constituents of concern (COCs)•Establish institutional controls to restrict access to the contaminant plumeProtect uncontaminated groundwater and surface water for current and future use•Prevent contamination of existing wells that could be affected by the plume and in adjacent groundwater•Prevent or minimize further migration of groundwater containing COCs within the Basin (plume containment)Return groundwater to their expected beneficial uses wherever practicable (aquifer restoration)•Prevent or minimize further migration of contaminants from source area to groundwater (source control)•Reduce contaminant concentrations within the area of the plume to levels that are safe for drinkingProtect environmental receptors•Reduce contaminant concentrations in the plume to levels that are safe for biological receptors that may be affected at the groundwater discharge pointCleanup LevelRestore pre‐contamination media qualityArea of AttainmentGroundwater and surface water within the source area and limits of plume extentRestoration Time FrameUncertain since source control/removal has not yet been achieved. Depending on the extent of residual secondary source areas (e.g. fine‐grained formations to which contaminants may adsorb then back diffuse over time), minimum restoration time frame following source control/removal may be one pore volume of the plume (i.e. current modeled range of average travel time across the plume extent is estimated from 17 to 30 years), although it is likely that multiple pore volumes may be required. Table 2: Interim Remedial Action Objectives -DRAFTCleanup LevelMaximum Contaminant LevelsArea of AttainmentPoint of compliance at water supply wellsRestoration Time FrameAs soon as can feasibly be implemented to support continued and uninterrupted water supplyInterim RAOsBasin RAOsPrevent exposure to groundwater containing COCs exceeding acceptable risk levelsProtect uncontaminated groundwater and surface water for current and future useReturn groundwater to its expected beneficial uses wherever practicableProtect environmental receptorsContinue to provide uninterrupted drinking water supply to consumers that meet safe consumption requirementsAchieve a concentration reduction to <50 ppb at drinking water wells to avoid “impaired source” designation, which would trigger DDW 97‐005 compliance requirementsDesign and implement remedies without increasing existing volume of groundwater impacted by COCs AGENDA SOUTH TAHOE PUBLIC UTILITY DISTRICT TAC Meeting 3 South YFeasibility Study of Remedial Alternatives(D1712508) Tuesday, October 23, 2018 9:30 AM- 12:00 PM Go To Meeting Conference Call Call-In Number: +1 (872) 240-3412; Access Code: 794-898-717 X:\Projects\General\17W006_So Y FS\4.0 TAC\Mtng 3_Oct 2018\Agenda_7W006_ TAC Proj Mtng 3_20181023.docx 3 ATTACMENT B Remedial Scenario Definition Handouts • 2016 – 2018 PCE Distribution (Field Data) • 2018 PCE Distribution- Model Simulated Contours (lyr 1) • 2024 PCE Distribution- Model Simulated Contours (lyr 1) • Model Alternatives • Proposed Replacement Well Locations (for discussion purposes only) • DRI Model Layering MW-10A, B, and C MW-4A, B, and CJ5: 338 J4: 718J3: 351J2: 694 5E: 124 J6: 0.68 J1: 9.95 TEN: 0.25 ROG: 0.78 KM2: 0.25 KM1: 0.25 HMW-4: 11 FIF: 1040 TATA: 4.34 MW-9B: 9.2 LTB4: 1.03LTB3: 1.18LTB2: 0.72LTB1: 1.01 HMW-5: 9.5HMW-3: 2.3 DUN2: 33.1 DUN1: 3.11 MW-8B: 0.26 LW-MW-5S: 51LW-MW-2D: 16LW-MW-1S: 93LTLW-GW-1: 123 LTLW-GW-7: 28.6LTLW-GW-6: 6.38 LTLW-GW-3: 31.7 LBWC #3 0100200 300400 000Tata #4South Y Well Clement Well Document Path: Z:\Projects\STPUD PCE Grant\Events\20180910\Area_w_parcels_zoom_ownership.mxdService Layer Credits: Source: Esri, DigitalGlobe, GeoEye, EarthstarGeographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GISUser Community 0 250 500 750125Feet Legend Data Used for Contouring100 ug/L PCE ContoursLake Tahoe Unified School DistrictLukins Brothers Water Co.Tahoe Keys Property Owners Association Parcel Boundaries by OwnershipFederalLocalOther LocalPrivateState !! ! ! ! ! ! ! !!! ! ! !! ! ! ! ! ! ! ! ! !! !!! ! ! !! !! ! ! ! ! ! !! ! ! ! !! !! ! ! !150.5105 0 100CHRIS JULIE HELEN1HELEN2 PALOMA SOUTHY SUNSET BAYVIEW CLEMENT ALTAHOE1ALTAHOE2 TATALANE1TATALANE2TATALANE3 TATALANE4 TAHOEKEYS1 TAHOEKEYS2 TAHOEKEYS3 LUKINSBROTHERS3 LUKINSBROTHERS4 LUKINSBROTHERS1 LUKINSBROTHERS2LUKINSBROTHERS5 Sources: Esri, HERE, Garmin, USGS, Intermap, INCREMENT P, NRCan, EsriJapan, METI, Esri China (Hong Kong), Esri Korea, Esri (Thailand), NGCC, ©OpenStreetMap contributors, and the GIS User Community 0 0.2 0.4 0.6 0.80.1 Miles 2018 Simulated PCE Contours (ug/l) !! ! ! ! ! ! ! !!! ! ! !! ! ! ! ! ! ! ! ! !! !!! ! ! !! !! ! ! ! ! ! !! ! ! ! !! !! ! ! !150.51050CHRIS JULIE HELEN1HELEN2 PALOMA SOUTHY SUNSET BAYVIEW CLEMENT ALTAHOE1ALTAHOE2 TATALANE1TATALANE2TATALANE3 TATALANE4 TAHOEKEYS1 TAHOEKEYS2 TAHOEKEYS3 LUKINSBROTHERS3 LUKINSBROTHERS4 LUKINSBROTHERS1 LUKINSBROTHERS2LUKINSBROTHERS5 Sources: Esri, HERE, Garmin, USGS, Intermap, INCREMENT P, NRCan, EsriJapan, METI, Esri China (Hong Kong), Esri Korea, Esri (Thailand), NGCC, ©OpenStreetMap contributors, and the GIS User Community 0 0.2 0.4 0.6 0.80.1 Miles 2024 Simulated PCE Contours (ug/l) AGENDA SOUTH TAHOE PUBLIC UTILITY DISTRICT TAC Meeting 3 South YFeasibility Study of Remedial Alternatives(D1712508) Tuesday, October 23, 2018 9:30 AM- 12:00 PM Go To Meeting Conference Call Call-In Number: +1 (872) 240-3412; Access Code: 794-898-717 X:\Projects\General\17W006_So Y FS\4.0 TAC\Mtng 3_Oct 2018\Agenda_7W006_ TAC Proj Mtng 3_20181023.docx 4 Model Alternatives – see D_Alts_modeling_101918.xlsx !!!!!!!!!!!!!!!!!!!! !$1 @A@A@A @A@A !. @A@A !. @A@A !@ $1 $1 $1 $1 $1 $1 $1 MW-10A, B, and C MW-4A, B, and C LBWC #3 EW-1 MW-7DMW-7C EW-4D Rockwater Tahoe Keys Well #3 Tahoe Keys Well #2 Tahoe Keys Well #1 Lukins Brothers Well No.5 Lukins Brothers Well No.4 Lukins Brothers Well No.2 Lukins Brothers Well No.1 EW-4C903 Eloise (SAA)Document Path: M:\Projects\STPUD PCE Grant\Events\20180910\Area_w_parcels_zoom_ownership.mxdService Layer Credits: Source: Esri, DigitalGlobe, GeoEye, EarthstarGeographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GISUser Community 0 500 1,000 1,500250Feet$ Legend Lake Tahoe Unified School DistrictLukins Brothers Water Co.Tahoe Keys Property Owners AssociationParcel Boundaries by OwnershipFederalLocalOther LocalPrivateState RW-A RW-B RW-C RW-E RW-F RW-D LBWC 4 TKWC 2 L1 L2 L3 L4