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STPUD Item 11.2 Groundwater F Modeling Report1 Marla Sharp From:Andrew Kopania <akopania@sbcglobal.net> Sent:Wednesday, July 31, 2019 10:11 AM To:'Carter, Tricia@Waterboards'; Ivo Bergsohn Cc:'Jennifer Lukins (jennifer@lukinswater.com)'; 'Kirk Wooldridge (kwooldridge@tahoekeyspoa.org)'; 'Sachi Itagaki'; Susan Rybarski; Mark B. Hausner (Mark.Hausner@dri.edu); Reeves, Robert@Waterboards (Robert.Reeves@waterboards.ca.gov); Jennifer Lau Subject:Re: STPUD (Agrmt No. D1712508) - Item 11.2 Groundwater F&Transport Modeling Report - Alternative 2 Need for Modification - Proposed Revisions Ivo- Appreciate you copying us on this. I am available Friday at 10 AM if your intent was to also have the Keys on the call at that time. Andy Kopania On Tuesday, July 30, 2019, 06:07:16 PM PDT, Ivo Bergsohn <Ibergsohn@stpud.dst.ca.us> wrote: Hi Tricia- I met with KJC and DRI over a conference call this morning to discuss possible revisions to Alternative 2 of the Interim Remedial Alternatives selected for the South Y Feasibility Study (Agreement D1712508). Proposed revisions considered during our call are presented in the attached slide set. If available, we would welcome an opportunity to walk-through these slides and receive input from the broader group concerning the extra work being proposed for this project. If possible, we would like to meet over a brief conference call (1/2 – 1 hour max) sometime before the end of this week. At this time, I’m proposing a 10:00 AM call this coming Friday (8/2). Let me know if this works for you or send me an alternate date/time that works best for Robert and yourself. My schedule’s flexible this week. Thanks, Ivo Bergsohn, PG, HG Hydrogeologist South Tahoe Public Utility District 1275 Meadow Crest Drive 2 South Lake Tahoe, CA 96150 (530)543-6204 From: Ivo Bergsohn Sent: Friday, July 26, 2019 9:06 AM To: 'Carter, Tricia@Waterboards' Cc: John Thiel; Jennifer Lukins (jennifer@lukinswater.com); Kirk Wooldridge (kwooldridge@tahoekeyspoa.org); Sachi Itagaki Subject: RE: STPUD (Agrmt No. D1712508) - Item 11.2 Groundwater F&Transport Modeling Report - Alternative 2 Need for Modification Hi Tricia- Thanks for your time yesterday afternoon which we discussed the need to modify Alternative 2 – Targeted Pumping as part of the South Y Feasibility Study. A copy of the letter received this week from the Tahoe Keys Property Owners Association (TKPOA) describes their position with regard to the proposed use of Tahoe Keys Water Company (TKWC) Wells as part of an interim remedial alternative (attached). In response to this letter, TKWC Well No. 2 will be removed from Alternative 2 and replaced using extraction well (s) to provide the hydraulic control and removal of PCE from groundwater previously provided by TKWC No. 2. The project team is currently reviewing data from the Lahontan Regional Water Quality Control Board Regional Plume Characterization to help site and design these wells in terms of appropriate screen intervals and well depths. We will also reconsider possible use of the Lukins Brothers Water Company (LBWC) Well No. 4 site as a possible extraction well location. The project teams short-term goal is to develop modifications to Alternative 2 to a level that could be evaluated using the South Y Fate & Transport Model by the end of next week. I’ll follow-up with an update as this work progresses. The modeling evaluation work already completed for this project and documented in the recently submitted Fate & Transport Modeling Report (DRI, June 28, 2019) underscores the importance of operating LBWC Well No. 5 for hydraulic control and removal of PCE from groundwater in the South Y Area. With the removal of TKWC wells from Alternative 2, the importance of well head treatment for LBWC No. 5 is only increased to make Alternative 2 viable. Feel free to contact me should you have any questions or immediate concerns with the direction that we are taking to conduct the Feasibility Study. Thanks, Ivo Bergsohn, PG, HG 3 Hydrogeologist South Tahoe Public Utility District 1275 Meadow Crest Drive South Lake Tahoe, CA 96150 (530)543-6204 From: Carter, Tricia@Waterboards [mailto:Tricia.Carter@Waterboards.ca.gov] Sent: Thursday, July 25, 2019 4:45 PM To: Ivo Bergsohn Subject: RE: STPUD (Agrmt No. D1712508) - Item 11.2 Groundwater F&Transport Modeling Report Hi Ivo, Let me know if you are able to share the comment letter we discussed. It will help facilitate my discussion with Robert tomorrow and provide emphasis on the need to expedite the funding for the SRF project. Thanks, Tricia From: Carter, Tricia@Waterboards Sent: Thursday, July 25, 2019 3:52 PM To: Ivo Bergsohn <Ibergsohn@stpud.dst.ca.us> Subject: RE: STPUD (Agrmt No. D1712508) - Item 11.2 Groundwater F&Transport Modeling Report Sounds good. From: Ivo Bergsohn <Ibergsohn@stpud.dst.ca.us> Sent: Thursday, July 25, 2019 3:50 PM To: Carter, Tricia@Waterboards <Tricia.Carter@Waterboards.ca.gov> Subject: RE: STPUD (Agrmt No. D1712508) - Item 11.2 Groundwater F&Transport Modeling Report 4 Ok, I’ll try for around 4:15 Talk with ya soon, -Ivo From: Carter, Tricia@Waterboards [mailto:Tricia.Carter@Waterboards.ca.gov] Sent: Thursday, July 25, 2019 3:49 PM To: Ivo Bergsohn Subject: RE: STPUD (Agrmt No. D1712508) - Item 11.2 Groundwater F&Transport Modeling Report You bet. From: Ivo Bergsohn <Ibergsohn@stpud.dst.ca.us> Sent: Thursday, July 25, 2019 3:44 PM To: Carter, Tricia@Waterboards <Tricia.Carter@Waterboards.ca.gov> Subject: RE: STPUD (Agrmt No. D1712508) - Item 11.2 Groundwater F&Transport Modeling Report Hi Tricia- Can I give you a call later this afternoon? -Ivo From: Carter, Tricia@Waterboards [mailto:Tricia.Carter@Waterboards.ca.gov] Sent: Thursday, July 25, 2019 3:05 PM To: Ivo Bergsohn Cc: Susan Rybarski; Sachi Itagaki; Mark B. Hausner Subject: RE: STPUD (Agrmt No. D1712508) - Item 11.2 Groundwater F&Transport Modeling Report 5 Hi Ivo, Any updates? Tricia From: Ivo Bergsohn <Ibergsohn@stpud.dst.ca.us> Sent: Tuesday, July 16, 2019 8:55 AM To: Carter, Tricia@Waterboards <Tricia.Carter@Waterboards.ca.gov> Cc: Susan Rybarski <Susan.Rybarski@dri.edu>; Sachi Itagaki <SachiItagaki@kennedyjenks.com>; Mark B. Hausner <Mark.Hausner@dri.edu> Subject: RE: STPUD (Agrmt No. D1712508) - Item 11.2 Groundwater F&Transport Modeling Report Hi Tricia- We are currently waiting to hear the direction TKPOA Board has given staff concerning their continued level of participation as part of the recommended remedial alternative. This is anticipated at their next Board Meeting scheduled for this Saturday (7/20). In case TKPOA plans to withdraw from the FS we are considering a Scenario 2b. Scenario 2b would involve adding a cost item for the drilling and construction of a replacement extraction well, wellhead treatment system and discharge. The extraction well would be placed near the centerline of the plume, upgradient of TKWC2 and designed to pump groundwater from Model Layer 2 (TKZ4); approximately 130 – 200 ft bgs. The well would be designed as a production well (at 550 gpm) with a wellhead treatment system for the removal of PCE from groundwater. Discharge options for this well would include potable reuse (connection to LBWC water distribution system); and/or surface water discharge under a NPDES permit. I believe that the work DRI performed under Alternative 4 may be adequate to estimate the contaminant mass removal for the replacement extraction well proposed under Scenario 2b. We’ll need to check on this with DRI after we hear back from TKPOA and depending on the proposed location of the replacement extraction well. DRI is working on an addendum to address the comment concerning a Table of Data Sources used for the groundwater modeling. Let me know if you want to talk further about this or if you have any other questions about the FS. 6 Thanks, Ivo Bergsohn, PG, HG Hydrogeologist South Tahoe Public Utility District 1275 Meadow Crest Drive South Lake Tahoe, CA 96150 (530)543-6204 From: Carter, Tricia@Waterboards [mailto:Tricia.Carter@Waterboards.ca.gov] Sent: Monday, July 15, 2019 3:03 PM To: Ivo Bergsohn Cc: Susan Rybarski; Sachi Itagaki; Mark B. Hausner Subject: RE: STPUD (Agrmt No. D1712508) - Item 11.2 Groundwater F&Transport Modeling Report Hi Ivo, In addition to my comment below, can you confirm how you intend to address Tahoe Keys concern of their wells being included as part of the remedy. Do you intend to run another scenario with the model that does not include the Tahoe Key’s wells, but accounts for their pumping influence to meet the demand of their customers? Thanks again, Tricia From: Carter, Tricia@Waterboards Sent: Tuesday, July 09, 2019 12:57 PM To: Mark B. Hausner <Mark.Hausner@dri.edu>; Ivo Bergsohn <Ibergsohn@stpud.dst.ca.us> Cc: Susan Rybarski <Susan.Rybarski@dri.edu>; Sachi Itagaki <SachiItagaki@kennedyjenks.com> Subject: RE: STPUD (Agrmt No. D1712508) - Item 11.2 Groundwater F&Transport Modeling Report Hi Ivo, 7 Can you confirm how the first bullet was addressed? I see the bullets 2-4 were addressed in the final document. Thanks for taking the time to put the comments together, Tricia From: Mark B. Hausner <Mark.Hausner@dri.edu> Sent: Tuesday, July 02, 2019 9:58 AM To: Ivo Bergsohn <Ibergsohn@stpud.dst.ca.us>; Carter, Tricia@Waterboards <Tricia.Carter@Waterboards.ca.gov> Cc: Susan Rybarski <Susan.Rybarski@dri.edu>; Sachi Itagaki <SachiItagaki@kennedyjenks.com> Subject: RE: STPUD (Agrmt No. D1712508) - Item 11.2 Groundwater F&Transport Modeling Report Hi Ivo and Tricia: Below is a list of verbal comments conveyed to us during the TAC meeting that were incorporated into the final report:  Add a table of data sources used to calibrate the model, being sure to include data generated as part of the pre- design investigation  Expand the discussion of spatial and temporal data gaps and how future data could be collected to most effectively reduce model uncertainty  Add a note to scenarios when and if the simulated concentrations or pumping rates exceed the nominal GAC capacity (this was requested by LBWC, and we added the note for both LBWC and TKWC)  Add language from STPUD’s attorney to limitations section to address potential liability issues for the District and DRI. We also received written comments from Ivo and Gary at the district that we incorporated into the final document. It was noted during the meeting that effective limitations on pumping were determined by the permit issued and not by the well capacity, and Salvador Turrubiartes reiterated that in his written comments following the meeting. Ivo provided us with a copy of Mr. Turrubiartes’ comments, and we kept those comments in mind during the revision. We considered the specific comments outside of the scope of the modeling report, since the simulated scenarios were provided to us by the stakeholders in the feasibility study. Please feel free to contact me with any other questions, or if any of the comments or responses remain unclear. Thanks, Mark Mark B. Hausner, Ph.D. Assistant Research Professor, Hydrology 8 Division of Hydrologic Sciences Desert Research Institute 775-673-7352 mark.hausner@dri.edu From: Ivo Bergsohn <Ibergsohn@stpud.dst.ca.us> Sent: Tuesday, July 2, 2019 9:12 AM To: 'Carter, Tricia@Waterboards' <Tricia.Carter@Waterboards.ca.gov> Cc: Susan Rybarski <Susan.Rybarski@dri.edu>; Mark B. Hausner <Mark.Hausner@dri.edu>; Sachi Itagaki <SachiItagaki@kennedyjenks.com> Subject: RE: South Y Feasibility Study (Agreement No. D1712508) - Item 11.2 Groundwater Fate and Transport Modeling Report Hi Tricia- Written comments were received from Salvador Turrubiartes (SWRCB-DDW). I have asked DRI to provide a list of the verbal comments they noted from the TAC during TAC Meeting 5. The meeting minutes from TAC 5 still need to be prepared. No comments were received from B. Grey, LRWQCB. Comments received from TKPOA (see attached email strings)  Use of semi-annual vs. annual time-steps;  Request for Modeling Reports referenced in F& T Report Outside of the review comments which I provided during development of the F&T Report, I believe that’s it, 9 Ivo Bergsohn, PG, HG Hydrogeologist South Tahoe Public Utility District 1275 Meadow Crest Drive South Lake Tahoe, CA 96150 (530)543-6204 From: Carter, Tricia@Waterboards [mailto:Tricia.Carter@Waterboards.ca.gov] Sent: Monday, July 01, 2019 2:55 PM To: Ivo Bergsohn Cc: Susan Rybarski; Mark B. Hausner (Mark.Hausner@dri.edu); Sachi Itagaki Subject: RE: South Y Feasibility Study (Agreement No. D1712508) - Item 11.2 Groundwater Fate and Transport Modeling Report Hi Ivo, Do you have record of all TAC comments and documentation of the responses? (e.g., I recall the data gap discussion from our TAC meeting that DFA and RB noted. Also, reference to information obtained in the pre-design investigation and how it was used to inform the model was also a DFA comment). Did the Regional Board and Tahoe Keys provide any additional comments? Thanks, Tricia From: Ivo Bergsohn <Ibergsohn@stpud.dst.ca.us> Sent: Friday, June 28, 2019 10:47 AM To: Carter, Tricia@Waterboards <Tricia.Carter@Waterboards.ca.gov> Cc: Susan Rybarski <Susan.Rybarski@dri.edu>; Mark B. Hausner (Mark.Hausner@dri.edu) <Mark.Hausner@dri.edu>; Sachi Itagaki <SachiItagaki@kennedyjenks.com> Subject: South Y Feasibility Study (Agreement No. D1712508) - Item 11.2 Groundwater Fate and Transport Modeling Report 10 Hi Tricia- I am pleased to provide electronic copy of the Fate and Transport Modeling of the South Y PCE Groundwater Contamination Plume . This report was prepared by the Desert Research Institute (DRI) for the Feasibility Study of Remedial Alternatives to Mitigate Tetrachloroethylene Contamination, Agreement No. D1712508, and is submitted for your approval in accordance with Scope of Work Item 11.2 of the Agreement. Any comments received from the TAC have been addressed in this report. Upon your approval the attached report will be uploaded to FAAST. Thanks again for your kind assistance throughout this project, Ivo Bergsohn, PG, HG Hydrogeologist South Tahoe Public Utility District 1275 Meadow Crest Drive South Lake Tahoe, CA 96150 (530)543-6204 This email message has been delivered safely and archived online by Mimecast. This email message has been delivered safely and archived online by Mimecast. This email message has been delivered safely and archived online by Mimecast. 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