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17W006 Meeting Notes_TAC Proj Mtng 2_061218_finalMeeting Notes SOUTH TAHOE PUBLIC UTILITY DISTRICT TAC Meeting 2 South Y Feasibility Study of Remedial Alternatives (D1712508) Tuesday, June 12, 2018 9:30 AM- 12:45 PM District Board Room X:\Projects\General\17W006_So Y FS\4.0 TAC\Mtng 2_ Jun 2018\Notes\17W006 Meeting Notes_TAC Proj Mtng 2_061218_final.docx 1 1) Welcome. Sachi Itagaki with Kennedy/Jenks introduced herself and led the meeting. a) Introductions Kennedy/Jenks: Sachi Itagaki, Mike McLeod (Telephone), Jennifer Lau, (Telephone) State Water Resources Control Board - DFA: Tricia Carter, Robert Reeves (RR/DFA) State Water Resources Control Board – DDW: Salvador Turrubiartes (Telephone) City of South Lake Tahoe: Randy Carlson, Jason Burke Lukins Brothers Water Company: Jennifer Lukins (Telephone) Lahontan Regional Water Quality Control Board: Brian Grey (Telephone) Tahoe Keys Water Company: Rick Robillard South Tahoe PUD: Ivo Bergsohn, Shannon Cotulla, Richard Solbrig, John Thiel, Heidi Baugh TAC Roster: Inspection of the Technical Advisory Committee (TAC) Roster shows that all of the members of the Stakeholders Advisory Group (SAG) are included on the TAC. Question was raised about the necessity of maintaining separate meetings between the two groups. The South “Y” FS SAG is a subset of the GWMP SAG which is an existing groundwater forum. The GWMP SAG is also regularly updated about the progress of this project. In addition to the SAG, the District will also convene Public Meetings to inform and receive comment from the community. The initial meeting in February was extremely well attended (JB). District staff was credited for having done a great job of public outreach (IB). TC asked is there a need for separate meetings since the same people are on TAC. RR/DFA may lose ability to have more detailed technical discussion if meetings were not separate. TAC is comprised of the regulators and agencies involved. In this case the responsible parties (RP) and other members of the public will be informed. He thinks we can go either way, but that we should reserve the option for separate meetings. Coordination between the water purveyors, the City and TAC is key for project success. For example, City involvement on TAC stream-lined the permitting process for the Pre- Design Investigation (PDI). Important that water purveyors are included on TAC as changes considered by each water company need to be coordinated with actions being considered by the TAC as part of the FS. TC didn’t see a problem with including the SAG as part of the TAC. RR/DFA - technical review of project deliverables is responsibility of the TAC; TAC should reserve the right to conduct a meeting separate from the SAG depending on the topics at hand. It was agreed that given the strong need for coordination between the Agencies, City and Meeting Notes SOUTH TAHOE PUBLIC UTILITY DISTRICT TAC Meeting 2 South Y Feasibility Study of Remedial Alternatives (D1712508) Tuesday, June 12, 2018 9:30 AM- 12:45 PM District Board Room X:\Projects\General\17W006_So Y FS\4.0 TAC\Mtng 2_ Jun 2018\Notes\17W006 Meeting Notes_TAC Proj Mtng 2_061218_final.docx 2 Water Purveyors that the TAC meetings will continue to be inclusive of the SAG. TC to confirm whether TAC can satisfy scope of the SAG. Summary of Work Completed to Date Establishment of SAG; establishment of TAC; completion of the PDI Work Plan (including the MRP and QAPP); and completed the PDI Site Access Agreements. signed by all parties; attained required Permits (Well Construction; Obstruction in ROW), achieved with assistance from the City; Phase 1 – Test Hole Drilling, Sampling & Analyses and Baseline Sampling (groundwater sampling of neighboring monitoring wells, concurrent with the Test Hole Drilling and Sampling program). Progress has been made on the MOU (discussed further under Item 7) 2) PDI Field Work – Phase 1 Results Challenges in scheduling the drilling rig and additional time needed to receive soils laboratory and water quality results led to phasing the project, requiring two mobilizations and extended the schedule needed to complete the PDI. a) Handouts • 3a1 draft boring log with WQ data- soils SI went over the Boring and Well Construction Log slide pointing out “Samples”, “Drill Depth”, “Backfill Details” and “Sample Description and Drilling Remarks” columns explaining a little further what they represented. During presentation of TVS Basin Section G-G’ IB noted the various wells and their current status (active, active with treatment, inactive, destroyed). He explained that the upper most water-bearing zone (TKZ5) is cased off in the TK2 Well with the seal set into the 94-100’ Aquitard encountered in the Test Hole. TK2 pumps groundwater from the water-bearing zone immediately below this aquitard (TKZ4). RR noted that PCE In this well is typically about 18 – 22 ppb and is run seasonally as a lag-lag well in the TKWC system. TK1 is at 2.1ppb, at highest it was 4. SI pointed out that the “Samples” column showed the locations of samples. First zone test 31-37’. Identification of zone test intervals were based, in part, on subsurface information collected from a nearby CPT boring (EKI Off-Site Investigation, Sounding 5ECPT). Standard Penetration Tests (SPTs) were collected across fine grained intervals; blow counts are shown along the left side of the log. The Test Hole Boring Log is generally consistent with the CPT Sounding; with the exception of the finer grained horizon at 54-58’ in the Sounding which was not found in the 6” Sonic Meeting Notes SOUTH TAHOE PUBLIC UTILITY DISTRICT TAC Meeting 2 South Y Feasibility Study of Remedial Alternatives (D1712508) Tuesday, June 12, 2018 9:30 AM- 12:45 PM District Board Room X:\Projects\General\17W006_So Y FS\4.0 TAC\Mtng 2_ Jun 2018\Notes\17W006 Meeting Notes_TAC Proj Mtng 2_061218_final.docx 3 Core. Major fine-grained confining layers were found at 38.5’-41’ see K-values from soils tests (permeability); 94’ – 100’ and at 150’ (bottom of Test Hole). Soils samples from both the fine-grained confining layer horizons and the coarser- grained water-bearing test zones were collected and analyzed for soils permeability (cm/s). Formation tests were completed for four of the five zones identified for zone testing. One of the tests was aborted due to difficulty in sustaining a constant flow. Water Quality Results. Zone 2 Interval ( 41-51’) showed highest concentrations of PCE (66 ppb). Benzene levels were also high (112 ppb) in this zone. Benzene was solely detected in the water sample collected from Zone 2 and not in the other zones or in the Baseline Samples from the neighboring monitoring wells. IMPORTANT FINDING- BETX will need to be considered in the mix of compounds for well head treatment. • 3a2 Map with new WQ sampling Results from EW-1 boring and taken from monitoring wells in the area. SI pointed out that if we look at depths we will notice consistencies. Baseline samples were collected at onset of Test Hole drilling program are concurrent with work at the Eloise site. • 3a3 Map with 2017 data from Workplan Results of the Workplan were submitted earlier. 2017 WQ Data was used to site the PDI Test Hole location down-gradient of hot spot. 2017 WQ Data (PDI Workplan, Appendix D) show highest levels (>1,000 ppb) found in the CPT FIF at 45 – 49’ depth (near intersection of 5th Street and Eloise), upgradient of the Test Hole location. High concentrations were also found in CPT samples collected along James Avenue in the 100’s of PPB. LRWQCB samples collected from MW4 (within 100’ of Test Hole) showed highest PCE at 86 ppb from a depth of 35 – 50’. RR noted that PCE at TK2 values remain in the 18 -22 ppb range • 3a4 Table with WQ Results Tabulated version (for additional perspective see 3a5) General water quality data will be used to characterize water types; water quality data collected from the LBWC #4 (during 2016 Suitability Investigation) will be used to augment the data set to look for differences between water-bearing Meeting Notes SOUTH TAHOE PUBLIC UTILITY DISTRICT TAC Meeting 2 South Y Feasibility Study of Remedial Alternatives (D1712508) Tuesday, June 12, 2018 9:30 AM- 12:45 PM District Board Room X:\Projects\General\17W006_So Y FS\4.0 TAC\Mtng 2_ Jun 2018\Notes\17W006 Meeting Notes_TAC Proj Mtng 2_061218_final.docx 4 zones. Inspection of WQ results show that highest levels of PCE were detected in zone test samples collected from the 30-35’ (30.7 ppb) and 41-51’ (66 ppb) intervals. Levels of PCE found in these samples are consistent with PCE detected in MW- 4B (64 ppb). PCE was also detected in MW-7C (3.4) and MW-7D (14 ppb). PCE was not detected in samples collected from MW-10B, MW-10C and EW-4D. Results suggest narrow linear plume geometry. • 3a5 Vertical Distribution of PCE/TCE Vertical distribution of PCE/TCE concentrations is shown on plot of concentrations and sample (well screen interval) depths. Inspection of plot shows that MW4B well screen crosses fine-grained interval at 38.5 – 41 feet. Many monitoring wells were installed through site area in early 2000’s as part of MtBE investigations. Construction of these wells across fine-grained intervals layers likely compromise effectiveness of these intervals as confining layers restricting the vertical movement of PCE contamination. Example - Swiss Mart Results (Q1 2003) show high PCE concentrations to depths of 80’. PCE in MW- 7D and TCE in Z4 sample from Test Hole indicates that 94-100’ interval is also compromised; identification of wells located within the plume and crossing this interval is especially needed in the FS as a means toward closing existing contaminant pathways. • 3a6 Vertical Gradient Estimate Handout shows calculated vertical gradients from water level data collected from the Baseline Wells. Vertical gradients are typically on the order of -0.10 ft/ft. This is consistent with the vertical gradients calculated from groundwater levels measured in the Clement monitoring well cluster included in the PDI work plan. All calculated gradients are negative (-) showing the vertical direction of GW flow is directed downward through area. 3) Proposed Test Well Design for Phase II PDI a) Handouts- • 4a1 Permeability result summary Handout presenting the Laboratory Results received from the geotechnical soils lab (Geo-Logic Associates, 5/30/2018). • 4a2 Draft -Capture Zone Analysis(CZA) Handout 4a2 includes summary table of soils lab analyses results, annotated using Meeting Notes SOUTH TAHOE PUBLIC UTILITY DISTRICT TAC Meeting 2 South Y Feasibility Study of Remedial Alternatives (D1712508) Tuesday, June 12, 2018 9:30 AM- 12:45 PM District Board Room X:\Projects\General\17W006_So Y FS\4.0 TAC\Mtng 2_ Jun 2018\Notes\17W006 Meeting Notes_TAC Proj Mtng 2_061218_final.docx 5 Test Hole formation test zone identifiers. The lab permeability results are approximate values and are used to show relative differences in permeability between samples. The permeability results were used to calculate capture zone dimensions for a possible low flow well(s)\ constructed through these materials. Zone 1 has the relatively highest permeability; a low flow well through these materials would generate the minimum size capture zone expected from a Test Well. Using these calculations, a 5 gpm well would be expected to generate a capture zone width on the order of 2,000 – 4,000 feet up-gradient of the well. • 4a3 Single Well EW-1 Option 1 – Single well design Two screened intervals (28’ – 35’) and (44’ – 59’) separated using a bentonite seal in the annular space from between 38-44’; constructed in a single borehole crossing the 38.5 – 41’ fine-grained horizon; TD = 64’. • 4a4 Two well design* EW-1 Option 2 - Two Wells Design Two test wells constructed in two discrete boreholes; Shallow Well; screen interval 27.5 – 35’; TD = 38’; Deep Well; screen interval 44 – 59’; TD = 64’. Two well option would prevent any possible mixing/cross-contamination of groundwater zones above/below fine-grained interval through the Test Well. EW-1 Option 3 Complete only a single Shallow Well or a single Deep Well, as per the Two Wells design. b) Discussion/Test Well Value Is it appropriate to move forward with Test Well Construction? IB- If we did not complete Phase 2 how would this affect the Feasibility Study? Phase 2 test well would provide a means to conduct the aquifer test. This test would provide site specific pumping rates and contaminant loads for use in engineering pre-design. Lab permeability’s are estimates which could be used; but not as good as data from aquifer test. RR/DFA benzene data; suggests more and additional contamination. Can additional data be generated to identify source area, groundwater flow directions and contaminant pathways? Need water elevation maps for Meeting Notes SOUTH TAHOE PUBLIC UTILITY DISTRICT TAC Meeting 2 South Y Feasibility Study of Remedial Alternatives (D1712508) Tuesday, June 12, 2018 9:30 AM- 12:45 PM District Board Room X:\Projects\General\17W006_So Y FS\4.0 TAC\Mtng 2_ Jun 2018\Notes\17W006 Meeting Notes_TAC Proj Mtng 2_061218_final.docx 6 different zones, as part of this effort. Working with limited data set, will provide groundwater elevation maps to best resolution that data will allow. Baseline sampling includes three well clusters that would provide data points for groundwater elevation maps that could show local direction of horizontal flow in two zones. RR/DFA- would extraction well draw in contamination from multiple plumes and/or sites? Yes- the benzene data indicates gasoline compounds (BTEX) would be removed as well as chlorinated hydrocarbons. The TAC agrees with the proposed two well design option and moving forward with the proposed Test Well Construction and aquifer testing to complete the PDI. RR/DFA inquired whether further source area identification was part of LRWQCB’s planned investigation. BG - LRWQCB is focusing on having LT Laundry works implement investigative actions in compliance with the CAO. In addition, LRWQCB has almost completed review of historical data and information to identify potential responsible parties within the regional plume area. Over 100 sites have been identified with historical potential chlorinated hydrocarbons usage; including five (5) sites where PCE has been identified in soil. RR/DFA would like further information from LRWQCB about scope of proposed investigation. RR/DFA- Is a map available that shows potential source areas where CA Water Code section 13267 letters have or may be sent? BG-Maps have not been developed for this specific purpose, but can be produced, if needed. RR/DFA – where is Test Well location with respect to potential source areas? Test well is believed to be located near the down-gradient margin of the industrial portion of South Lake Tahoe. LBWC #4 located immediately north of Test Well is within a residential area. Industrial area extends south west to Industrial Avenue. At this time after more than 30 years of inspection; there is at least one substantial source area (former LTLW site). TC: Is there adequate GAC remaining for water treatment to complete the aquifer testing? Yes- flows during Test Hole construction and sampling were small than expected; PCE concentrations were also lower; sufficient GAC remains to complete the project. Source Area Identification: GEI Consultants provided summary of temporal and spatial distribution of PCE contamination as part of planning work completed for the FS. IB will be working on creating a map showing private wells located within the South Y PCE Plume, which will be useful for the FS. LRWQCB Investigation: RR/DFA would like to see a smaller search area for source Meeting Notes SOUTH TAHOE PUBLIC UTILITY DISTRICT TAC Meeting 2 South Y Feasibility Study of Remedial Alternatives (D1712508) Tuesday, June 12, 2018 9:30 AM- 12:45 PM District Board Room X:\Projects\General\17W006_So Y FS\4.0 TAC\Mtng 2_ Jun 2018\Notes\17W006 Meeting Notes_TAC Proj Mtng 2_061218_final.docx 7 area identification. TC - LRWQCB developed and costed out at DFA direction an investigation with a more regional focus and less specific. RR/DFA may need to be breaking it down. Implementation may need to happen sooner than a regional investigation for source area identification would allow. RR/DFA- source area identification is critical to understanding scope of problem; important that a potential source is not actively operating – IRA plan needs to be very carefully thought through. RR/DFA/TC – The feasibility study should move forward as discussed. Schedule: Phase II mobilization 6/24; Test Well Drilling & Construction 6/25 – 6/27; Aquifer testing (due to July 4 holiday; week of 7/9 – 7/13. 4) DRI Modeling Scenarios SI went through the DRI modeling scenarios and work using excerpts of DRI presentation dated April 2017. • Layer 1 - majority of contamination, uppermost water-bearing zone (TKZ5) • Layer 2 –immediately below regional aquitard; upper-most water-bearing zone used by TK 2 (TKZ4) • Red line: 2016 plume extent (estimated) used in fate and transport model. • Production wells vs model layer: shows correspondence between model layers; well screen intervals and regional zone designations used by STPUD. • Simulated time periods: transient historical through 2016; predictive through 2066 • Inflows: recharge; in-basin flows; and outflows ; streams, Lake Tahoe, well pumping • Specified head boundary conditions: – from TVS Basin Model • Hydraulic parameters: Noted downward gradient in the Y area and graph of down gradient depth. Stating that vertical migration does not occur until further down gradient (attributed to influence of pumping wells?). • PCE Source: Modeled as a single source located in up-gradient position at head of plume (south of former LTLW site). a) Handout • 5a excerpt of April 2017 DRI ppt SI walked group through DRI ppt. • 5b Proposed scenarios Table 1 from the original grant application: Potential Modeling Scenarios Possible Extraction Well Locations: remove 883/903 Eloise Avenue site (SAA Property) due to ND at MW-10 monitoring wells; Rockwater Well may still be a viable site. Meeting Notes SOUTH TAHOE PUBLIC UTILITY DISTRICT TAC Meeting 2 South Y Feasibility Study of Remedial Alternatives (D1712508) Tuesday, June 12, 2018 9:30 AM- 12:45 PM District Board Room X:\Projects\General\17W006_So Y FS\4.0 TAC\Mtng 2_ Jun 2018\Notes\17W006 Meeting Notes_TAC Proj Mtng 2_061218_final.docx 8 Drinking Water Wells Element: LBWC; abandon LBWC 2; LBWC 5 add wellhead treatment (750 gpm?); LBWC 4 – well destruction; add new deep replacement well at LBWC 4 site (?) – tentative, may be worth considering hydraulic effect of deep well at this location using F&T model. TK – range of wells at diff operating parameters; need to consider differing well configurations for TKWC wells; example TKWC 2 – model scenarios with/without upper screen interval; need confirmation from TKWC of well configuration and pumping alternatives being considered for PCE operations plan. Discharge Element– Sewer (extraction wells); treated water system reuse (Drinking Water Wells); Injection (as part of remediation strategy); all may be used in FS; depending on permitting needs and requirements. Modeling analysis would be used to test 15 scenarios in order to identify 7 most feasible for engineering feasibility analysis; next step is to clearly define the initial scenarios. Note Scenario 1 completed (?) = No Action Alternative. Next Step – Scenario Definition: Need Water Purveyor input by 6/18; Currently assume for TKWC Wells: TK3 - lead, TK2- lag, TK1 –lag-lag for predictive model (confirm possible TK2 screen interval changes; and any possible new locations/screen intervals for TK1 replacement well? and/or new GW source?) . District will contact TC/RR/DFA/BG for participation in upcoming Model KO meeting with DRI, KJC and Water Purveyors discussing modeling approach and initial scenario definition. Model KO anticipated sometime during before 7/4 holiday. b) Discussion/ Water Purveyor Objectives and Remedial Scenario Definition 5) Draft Feasibility Study Workplan Outline KJC seeking confirmation concerning FS Work Plan requirements; Item 10 of Agreement shows three elements: Plan & Approach; Remedial Action Objectives (RAO); and ARAR analysis. TC/RR/DFA confirmed requirements. 6) Draft Remedial Action Objectives a) Handout 7a – draft RAO Table SI walked group through the draft RAO table. Meeting Notes SOUTH TAHOE PUBLIC UTILITY DISTRICT TAC Meeting 2 South Y Feasibility Study of Remedial Alternatives (D1712508) Tuesday, June 12, 2018 9:30 AM- 12:45 PM District Board Room X:\Projects\General\17W006_So Y FS\4.0 TAC\Mtng 2_ Jun 2018\Notes\17W006 Meeting Notes_TAC Proj Mtng 2_061218_final.docx 9 b) Discussion First cut effort – South Y PCE Contamination Response. Ultimate objective would be to do groundwater extraction without treatment. Are we focusing on the immediate feasibility study, or action taken as a result of the feasibility study? FS will ultimately result in a recommended draft Interim Remedial Action (IRA) for Implementation. DFA to provide feedback on draft RAOs Measurement of Success: discussion - using contaminant mass removal versus using clean-up objectives. For this project, consider IRA as a groundwater clean-up rather than a water supply project. Mass removal would be useful for limited project; more easily measured and attainable than using objectives. Other considerations: Operations & Maintenance (O&M) over 20-year project life; Post project monitoring; 1 year after implementation; Size and Scale issue: use of a contaminant mass target versus PCE concentration contour; long-term O&M- Prop 1 Funding currently not available for O&M- IB suggested that RAO table attempt to identify and outline Agency Responsibilities; focus needs to be on long-term; FS needs to lead to an attainable effort (action); not a list of objectives; recommended project could include RP search (to assist cost recovery). Implementation Project Funding: discussion regarding possible funding options for implementation project; should this problem be raised with EPA in order to take advantage of Federal funds that could be used for this project? Availability of funds for long-term O&M are under consideration; South Lake Tahoe problem is likely from Mom/Pop operations that closed years ago; cost recovery from these parties may be fruitless; Does LRWQCB have experience implementing groundwater clean-ups/ yes- example Leviathan Mine Project; Many projects Water Agencies take the lead on groundwater clean-up where RPs cannot be found, example San Gabriel Valley; Orange County; in these cases EPA can step in and may assist in getting RPs to pay for it; Are any funding sources available that we are not tapping? SWRCB-DFA could not identify other programs at this time. Given this issue focus needs to be on the IRA that can having the greatest return using the funding available through unique opportunity provided through Prop 1;Long term clean-up is going to take a long time and be very expensive. 7) Draft Memorandum of Understanding for TAC (T. Carter) a) Handout 8a Meeting Notes SOUTH TAHOE PUBLIC UTILITY DISTRICT TAC Meeting 2 South Y Feasibility Study of Remedial Alternatives (D1712508) Tuesday, June 12, 2018 9:30 AM- 12:45 PM District Board Room X:\Projects\General\17W006_So Y FS\4.0 TAC\Mtng 2_ Jun 2018\Notes\17W006 Meeting Notes_TAC Proj Mtng 2_061218_final.docx 10 TC directed IB to run with what they have discussed—MOU. District edits are acceptable. Submit Draft MOU to TC for routing to the Regional Board for review. When approved it will get routed back around through the executive offices of Regional Board and SWRCB for signature, and then its final. Draft final to be returned to TC early next week; draft final to BG late next week. Then it circles back again for signature. 8) Upcoming Activities a) Next 6 Weeks • Phase 2 Drilling (6/24 – 6/27); • Aquifer Testing (7/9 – 7/13); • BHHRA (6/25 – 7/13); • FS Workplan (6/25). • Public Meeting 2 (tentative 7/31, 8/1, 8/2). Call into city for use of facility (council chambers). • Initiate Modeling Analysis. Initiate after 6/18 • FS Kickoff Meeting (Wk of 7/9) TC to schedule site visit during Phase 2 Drilling and/or Aquifer Testing. b) Next 12 Weeks • 9a Schedule Update 1 (6/5/2018) • Revolving around our objectives. Ivo likes the mass removal idea. 9) Site Visit (953 Eloise Avenue) Conducted traverse of 953 Eloise Avenue and neighboring up-gradient area; FIF CPT Location; LBWC #3, J5 CPT Location, former Hurzel Property, CSLT Stormwater system. On-site discussion: source area identification, possible monitoring well locations, well profiling benefits, LBWC #4 well abandonment and replacement well; recommended operation plans for LBWC and TKWC well production. Meeting adjourned at 14:00