D1712508_Mtng Notes_ TAC Proj Mtng 6_20191021AGENDA
SOUTH TAHOE PUBLIC UTILITY DISTRICT
TAC Meeting 6
South YFeasibility Study of Remedial Alternatives(D1712508-2)
Monday, October 21, 2019 10:00 AM- 12:00 PM
Conference Call/Webcast
Call-In Number: +1 (855) 813-2486; Access Code: 2817#
http://conf.kennedyjenks.com/conference/2817
X:\Projects\General\17W006_So Y FS\4.0 TAC\Mtng 6_Oct 2019\Meeting Notes\D1712508_Mtng Notes_ TAC Proj Mtng 6_20191021.docx
Attendees: Tricia Carter (TC-SWRCB); Ivo Bergsohn (IB-STPUD); Salvador Turrubiartes (ST- DDW); Brian Grey (BG-LRWQCB); Jeff Brooks (JB - LRWQCB); Jason Burke (JB-CSLT); Jennifer Lukins (JL_LBWC); Kirk Woolridge (KW- TKPOA); Robert Reeves (RR-SWRCB); Andrew Kopania (AK-TKPOA); Sachi Itagaki (SI-KJ); Jennifer Lau (JL-KJ);
Grace Chen (GC-KJ)
1) Welcome/Self Introductions 10:00
Kennedy Jenks (KJ) provided presentations for discussion of the Concepts and Costs for each of the three alternatives selected for detailed analysis in the Feasibility Study (FS).
2) Alternative 1: Base Treatment
Alternative 1 Base Treatment is the no action alternative, maintaining current levels of
PCE treatment and assuming emergency water provided by STPUD. Pumping is projected to meet water system demands based on past 10-year average water production data (2009 -2018).
System Capacities: Largest unit out of service criteria (as per Title 22 source water capacity requirements) not considered. Both LBWC and TKWC water systems have current capacities to meet Max Day Demand (MDD); assumes LBWC 5 returned to service with well head treatment to remove PCE from groundwater. Additional supply may
be required to fully meet Title 22 requirements for fire flow. Fire flow requirements are
assumed to be met using emergency water sourced by STPUD. PCE Removal: Based on DRI Modeling Evaluation Scenarios 1A/1B, ~350 – 2600 lbs. PCE concentrations predicted to fall below MCLs (< 4 µg/L) in all LBWC wells by 2040
and in all TKWC wells by 2045, under best-case conditions; and in all LBWC wells by
2058 and in all TKWC wells by >2068, under worst-case conditions. Costs ($): Capital Costs = $0; O&M (existing) = ~$500 – 1.1 M per year
Implementation (yrs): 0, continue existing operations
Discussion: RR-SWRCB: Incremental costs above Alternative 1 costs should be used for detailed analysis in FS.
3) Alternative 2: Targeted Pumping
Alternative 2 Targeted Pumping involves using pumping from LBWC 5 and LBWC 4R to
AGENDA
SOUTH TAHOE PUBLIC UTILITY DISTRICT
TAC Meeting 6
South YFeasibility Study of Remedial Alternatives(D1712508-2)
Monday, October 21, 2019 10:00 AM- 12:00 PM
Conference Call/Webcast
Call-In Number: +1 (855) 813-2486; Access Code: 2817#
http://conf.kennedyjenks.com/conference/2817
X:\Projects\General\17W006_So Y FS\4.0 TAC\Mtng 6_Oct 2019\Meeting Notes\D1712508_Mtng Notes_ TAC Proj Mtng 6_20191021.docx
maximize PCE Removal. LBWC-4R is a new replacement well planned to be installed at the LBWC 4 well site. The well is proposed to be constructed as a shallow well pumping
groundwater above depths of 150 feet. Well head treatment installed at LBWC -4R would be used to remove contaminants for potable re-use, discharge to sanitary sewer or discharge to CSLT storm water system. Pumping is projected to meet water system demands based on past 10-year average water production data (2009 -2018).
LBWC-4R Facility layout includes new replacement well (200 gpm capacity) located within VOC Treatment Facility Building, equipped with wellhead treatment system for removal of PCE from groundwater. Both GAC and PTA options were evaluated; GAC was found to have lower capital and O&M costs and will be used in detailed cost analysis for this Alternative
PCE Removal: Based on DRI Modeling Evaluation Scenarios 2A/2B, ~800 – 4200 lbs. PCE concentrations predicted to fall below MCLs (< 4 µg/L) in all LBWC wells by 2033 and in all TKWC wells by 2026, under best-case conditions; and in all LBWC wells by 2046 and in all TKWC wells by >2068, under worst-case conditions.
Costs ($) - GAC: Capital Costs = ~$625K – 1.3M; O&M = ~$1.2M – 2.6 M per year Implementation (yrs): 3 to 5
Considerations: Potable re-use is most cost effective means of disposal compared to discharge to sanitary sewer and/or discharge to CSLT storm sewer. Discussion: IB-STPUD: Would DDW permit the proposed replacement well (LBWC 4R) for potable re-use? ST-DDW: Yes, DDW would allow source if treated water meets
drinking water standards; RR-SWRCB: Contaminated sources are operated for potable re-use in southern California. These wells are required to meet DDW 97-005 requirements. AK-TKPOA: Treatment requirements for the replacement well needs to consider nutrients as well as drinking water standards; New PCE data from 2019 Regional Plume Characterization (RPC) should also be considered.
4) Alternative 3: Conversion to Surface Water Alternative 3 Conversion to Surface Water involves constructing a new surface water intake and intake pipeline in Lake Tahoe, a new on-shore surface water pump station, raw
water conveyance pipelines, surface water treatment plant (WTP) with new distribution system connections to the LBWC and TKWC water distribution systems. The new surface water system is sized to meet all Title 22 source water capacity requirements. Using these requirements, operating criteria for the WTP assumes flows of 0.2 – 1.3 MGD, with
AGENDA
SOUTH TAHOE PUBLIC UTILITY DISTRICT
TAC Meeting 6
South YFeasibility Study of Remedial Alternatives(D1712508-2)
Monday, October 21, 2019 10:00 AM- 12:00 PM
Conference Call/Webcast
Call-In Number: +1 (855) 813-2486; Access Code: 2817#
http://conf.kennedyjenks.com/conference/2817
X:\Projects\General\17W006_So Y FS\4.0 TAC\Mtng 6_Oct 2019\Meeting Notes\D1712508_Mtng Notes_ TAC Proj Mtng 6_20191021.docx
max day demands of 4.4 MGD. Peak hourly demands assumed to be met using a clearwell /chlorine contact basin. Fire flow requirements are assumed to be met using
emergency water sourced by STPUD. PCE Removal: Based on DRI Modeling Evaluation Scenarios 3A/3B, ~230 – 1400 lbs. PCE removal is 0 lbs after total conversion to surface water. PCE concentrations are not predicted to fall below MCLs (< 4 µg/L) for this Alternative.
Costs ($): Capital Costs = $40.3M – $86.4M; O&M (Pre-Implementation) = ~$500 – 1.1 M per year; (Post-Implementation) = ~$1.1 – 2.4 M per year Implementation (yrs): 15
Discussion: Cost considerations need to be considered in the IRAP include payment ability (in financial plan). Legal fees for attainment of water rights also need to be considered. AK-TKPOA: How was adequate water depth determined for surface water intake? KJ assumed water depth using lowest lake level elevation, managed by USBR.
5) Other Recommended Activities KJ provided presentations for discussion of other recommended activities regardless of the selected Alternative in the FS.
Discussion: AK-TKPOA: DRI Fate & Transport Model should be updated with new 2019 Regional Plume Characterization (RPC) data; TKPOA is very concerned by the high PCE concentrations detected up-gradient of TKWC1. RR-SWRCB: Updated Model may be helpful to identify further actions by LRWCB (?) to address this concern. BG- LRWQCB:
Work for other recommended activities needs to be prioritized. KJ should confer with LRWQCB and CSLT for agency input. 6) South Y Alternatives Evaluation
KJ provided presentations for discussion of evaluation methods used for detailed analysis in FS. These included use of screening criteria, remedial action objectives, costs and other specific criteria included in the FS workplan. Discussion: KJ – Is the evaluation adequate? RR-SWRCB: KJ is on the right path; Prop
68 funding needs to be considered as part of finance discussion in IRAP. No need for detailed project schedules for each Alternatives; provide project schedule only for preferred Alternative. Clarify need for governance plan; SI-KJ believes this requirement was removed from Agreement; TC-SWRCB will follow-up and check on this.
AGENDA
SOUTH TAHOE PUBLIC UTILITY DISTRICT
TAC Meeting 6
South YFeasibility Study of Remedial Alternatives(D1712508-2)
Monday, October 21, 2019 10:00 AM- 12:00 PM
Conference Call/Webcast
Call-In Number: +1 (855) 813-2486; Access Code: 2817#
http://conf.kennedyjenks.com/conference/2817
X:\Projects\General\17W006_So Y FS\4.0 TAC\Mtng 6_Oct 2019\Meeting Notes\D1712508_Mtng Notes_ TAC Proj Mtng 6_20191021.docx
7) Adjourn