Loading...
111918_FS_workplan_D1712508-final-cleanFeasibility Study Workplan 1 South Tahoe Public Utility District Feasibility Study of Remedial Alternatives to Mitigate Tetrachloroethylene Contamination Agreement No. D1712508 Feasibility Study Workplan Feasibility Study Objectives The objective of the feasibility study is to integrate the information obtained from the pre-design investigation and the alternatives evaluated in the groundwater modeling and conduct an engineering analysis. The analysis will identify the most cost effective means of removing tetrachloroethylene (PCE) from groundwater and the managed use of groundwater sources in order to maintain adequate drinking water supply and quality in the South Y area. As detailed below, the analysis will evaluate the alternatives for engineering considerations as to treatment and/or remediation process to prevent and/or clean up the groundwater contamination, the site improvements and infrastructure necessary to implement the alternative, and life-cycle costs to be used to further evaluate the feasibility of the screened alternatives. Feasibility Study Steps The steps to the feasibility study include: 1. Data Review with Feasibility Study Kick-off Meeting 2. Screen Modeled Alternatives for Engineering Evaluation (up to 7 Alternatives) 3. Define Infrastructure Needs (3 Alternatives) (including disposal/reuse options) 4. Develop Life Cycle Cost Estimates (3 Alternatives) 5. Initial Study Checklist for 3 Alternatives and Estimated Cost of Mitigation 6. Select and Develop Recommended Alternative 7. Implementation Plan for Recommended Alternative: Financial and Governance Plan 8. Document findings in Draft and Final Report The steps are detailed below. 1. Data Review with Feasibility Study Kick-off Meeting This step will include detailed review of: A. Preliminary Design Investigation (PDI) conducted to support this effort in order to obtain recent soils, aquifer, and groundwater quality information B. Recent reports such as: i. Lukins Brothers Water Company (LBWC) Preliminary Engineering Report (PER) Water System Improvements Related to PCE Contamination (May 2015) ii. Water Board Final PCE Investigation Report, (January 2016) iii. District South “Y” Extraction Well Suitability Investigation (GEI, June 2016) iv. Results of PCE Investigation for Tahoe Keys Property Owners Association (TKPOA), August 2016 (GEI, 2016). v. Off-site Groundwater Investigation Report (August 30, 2017) vi. Lake Tahoe Laundry Works (LTLW) Preliminary Planning Report (September 14, 2018) vii. TKPOA Well #2 vertical profiling, if available during Feasibility Study investigation Feasibility Study Workplan 2 C. Results of Groundwater/Contaminant Transport Modeling and confirmation of range of water quality and water supply objectives achieved by identified alternatives. D. Results of recent monitoring conducted by other entities including i. 2018 PDI sampling ii. LBWC and TKWC sampling iii. LTLW 2018 sampling as documented in 1.B.6. above iv. Other monitoring results that becomes available during the period of this feasibility study E. Plans and documents provided by the water purveyors that describe the existing extraction, treatment and distribution facilities including cost of operations, historic pumping/treatment data, etc. A meeting conducted during this task on 12 June 2018 included discussion with Technical Advisory Committee (TAC)/Stakeholder Advisory Group (SAG) regarding: A. Alternatives from Groundwater/Contaminant Transport Modeling to be analyzed in the Feasibility Study including flow rates, locations, PCE contamination levels and residuals disposal B. Updates on activities of the responsible parties and water purveyors C. Current conditions with regard to PCE concentrations, pumping and treatment A Transport Modeling Analysis/Engineering Evaluation Kick-Off Meeting was convened with the TAC/SAG on July 18, 2018. Topics of discussion for that meeting included: A. Detailed description of the local PCE Fate and Transport Model B. Approaches towards developing Remedial Alternative Scenarios for model simulation; and C. Other source area assumptions and water purveyor considerations to inform the evaluation of alternatives. This step includes preparation of a draft reference list. 2. Screen Modeled Alternatives for Engineering Evaluation Groundwater modeling will include analysis of a range of pumping and PCE containment alternatives (both extraction/treatment and in-situ remediation) that will result in the identification of up to seven alternatives that have been modeled and demonstrated to provide a range of PCE removal and water supply benefits. Each of the alternatives will be screened using criteria developed in discussion with TAC/SAG, for engineering and permitting characteristics, to identify the three alternatives that will be carried forward for more detailed analysis. A sample list of screening criteria is provided below: A. Ease of Construction; B. Operations and Maintenance; C. Disposal/Reuse Options; D. Permitting Requirements; E. Environmental Effects; and F. Preliminary Cost Specific alternatives will be developed during the groundwater modeling analysis of pumping and PCE containment alternatives. Specific detail and validation of findings regarding advantages and disadvantages to meet criteria will be developed for identified alternatives under this task. It is assumed that at least one alternative will include sufficient treatment for municipal water supply using an impaired water source that will require compliance with State Water Resource Control Board Feasibility Study Workplan 3 Policy Memo 97-005 – Policy Guidance for Direct Domestic Use of Extremely Impaired Sources (Policy Memo 97-005). The results of this screening analysis will be brought to the TAC/SAG for review and comment in a meeting. Other topics that will be brought to the stakeholders at that meeting will include: Approach to infrastructure needs; Basis for life-cycle costs; Assumptions for Initial Study checklist and estimated cost of mitigation; Criteria for selection of recommended alternative; and an implementation plan for the recommended alternative which are detailed below. This step includes preparation of a draft report section for review and comment. 3. Define Infrastructure Needs (3 Alternatives) (including disposal/reuse options) Conceptual level infrastructure improvements will be developed for the three preferred alternatives and include consideration of the following: A. Extraction facilities (new or existing) for municipal water supply and/or for PCE removal including depth and range of proposed flow rate(s) (average vs maximum day and seasonal variability) and seasonal/monthly operating assumptions, if any. B. For PCE treatment in drinking water, packed tower aeration and granular activated carbon (GAC) are considered best available technology (BAT). Other options include low profile air stripping or membrane degassing which are relatively newer and potentially innovative. A high-level feasibility comparison of the four treatment options, especially for applicability in the high altitude, low temperature environment of South Lake Tahoe will be developed. For the purposes of this evaluation either packed tower aeration and/or GAC treatment will be used in evaluating the three alternatives. A decision as to which treatment option will be used in the analysis will be made jointly between the TAC, Kennedy Jenks Consultants and the water purveyors. Relocation and reuse of the existing packed tower aeration treatment system from the South Tahoe Public Utility District’s Clement Well site for use at either the LBWC #5 or a possible replacement well site will also be evaluated. Conceptual PCE treatment facilities (new or existing) will be developed for the assumed flow rate of the extraction facilities, PCE removal estimates, residuals production rate and concentration. Depending on the alternative, treatment may result in disposal of groundwater and as required by the alternative, the treatment process will be appropriate to domestic reuse sufficient to meet State Water Resources Control Board Policy Memo 97-005 on use of extremely impaired sources including consideration of reliability features and whether multi- barrier treatment is needed will be prepared. Each option that includes potable water delivery will include disinfection to follow PCE removal treatment. Other treatment for constituents to meet secondary maximum contaminant limits (MCLs) such as iron, manganese, and taste and odor are not included in this work plan. Prior to seeking Division of Drinking Water approval for treatment, secondary MCLs, if applicable, will be evaluated in an Engineering Report during the permitting process. C. Pumping and conveyance facilities including estimated flow rates to deliver water from extraction to treatment facilities and then to disposal and/or to potable water distribution system. D. Disposal options for treatment residuals including flow rates, concentrations, and estimates of quantities for on-site storage, limitations on quantities and duration of storage based on concentrations of residuals, frequency of removal and/or conveyance of residuals, if any, to Feasibility Study Workplan 4 sanitary sewer. Regeneration versus single use of GAC (including vapor phase GAC if required for packed tower aeration discharges) will be evaluated. Air dispersion modeling for packed tower aeration emissions is not included in this scope of work. In addition to tables and narrative describing the necessary facilities for each alternative, figures will be prepared showing infrastructure for each alternative sufficient to estimate quantities. For those alternatives where existing supply reliability is thought to be impacted by the preferred alternative(s) (i.e. alternatives does not result in additional potable water supply), discussion of replacement water supply will be provided. This step includes preparation of a draft report section for review and comment. 4. Develop Life Cycle Cost Estimates (3 Alternatives) This task will include development of capital, operating and life cycle costs for the three alternatives. A. The costs for the alternatives will be developed based on a Class 5 level representing Planning to Feasibility Level information with an estimated accuracy range between -30 percent and +50 percent. B. Costs will be based on information provided in recent studies (updated to an agreed upon engineering cost index), recent project experience, and engineering judgment. C. Capital costs will be amortized over the life of the project and divided by the anticipated volume of water produced to provide an estimate of the unit capital cost per million gallons (MG). D. Operations and maintenance (O&M) costs will be developed for an estimate 50-year operational period based on current annual costs provided by water purveyors for typical energy rates, labor estimates, residuals disposal, and replacement of key components of infrastructure. O&M estimates will be developed in consultation with water purveyors to reflect actual, local experience. E. Capital, O&M, and life cycle costs will be developed for each of the three alternatives and a unit life cycle cost per MG will be presented in a cost comparison summary. Detailed and summary cost tables will be developed and integrated into the Feasibility Study as appropriate. F. Estimating cost for design, environmental compliance, permitting and property acquisition costs will be on a high level and assume a percent of construction and/or local land costs for property. This step includes preparation of a draft report section for review and comment. 5. Initial Study Checklist for 3 Alternatives and Estimated Cost of Mitigation The 12-page initial study checklist for compliance with CEQA (CEQA-IS) and the Tahoe Regional Planning Agency Initial Environmental Checklist for determination of environmental impact (TRPA-IEC) will be completed for each of the three alternatives. It is expected that potential impacts requiring mitigation for an alternative may occur in six out of seventeen checklist areas included within the CEQA-IS checklist identified below: A. air quality, B. greenhouse gas emissions, C. hazards and hazardous materials, D. hydrology and water quality, E. noise, and F. utilities and service systems. Feasibility Study Workplan 5 This step will also include identification of mitigation measures and costs of implementing mitigation. The initial study checklists, mitigation measures and costs of mitigation for the three alternatives will be summarized in the text and provided as an appendix to the draft report. 6. Select and Develop Recommended Alternative This step will compile the screening evaluation results for the three alternatives, the life cycle costs including mitigation for the three alternatives and include consideration of other factors, which have been previewed with the TAC/SAG in a meeting, such as: A. Threshold Criteria such as quantity of water produced and/or quantity of PCE removed B. Balancing Criteria such as time to achieve PCE reduction, use of existing infrastructure C. Long-Term Effectiveness and Permanence D. Reduction of Toxicity, Mobility or Volume of PCE plume through Treatment E. Short-Term Effectiveness F. Constructability and Cost including permitting considerations such as meeting Policy 95-007 Based on consideration of this broad range of factors, the alternatives will be ranked and selection of a recommended alternative will be made and presented to the TAC/SAG. Once the recommended alternative is identified, more specific site–specific materials will be developed to a conceptual design level, and documented with figures (such as conceptual site layouts) with narrative description, and updated capital costs. This step includes preparation of a draft report section for review and comment. 7. Implementation Plan for Recommended Alternative: Financial and Governance Plan This step includes development of an implementation plan for the recommended alternative including schedule for implementation, discussion of potential financing options including cost recovery from the responsible parties, a governance plan and stakeholder outreach. This step includes preparation of a draft report section for review and comment. 8. Draft and Final Report The draft report sections prepared and reviewed under the previous tasks will be compiled into a single draft report document that responds to the comments received on the draft sections. A final report will be prepared based on the comments on the draft report. Remedial Action Objectives Draft Remedial Action Objectives (RAO) were developed and presented to the TAC at 12 June 2018 meeting and are attached. It is anticipated that the RAO may evolve over the course of the Feasibility Study. 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 Proposition 1 Metrics of Success: Estimated mass of contaminant removed over the projected life of the project 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 in mid-plume area including groundwater < 100’ below ground surface with high concentrations of PCE in mid-plume and/or replacement wells in deeper aquifer outside of the plume 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 Anticipated remediation time frame is 30 years or less to remove the majority of PCE mass in groundwater in the mid-plume area cost effectively 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. Feasibility Study Workplan 7 Applicable or Relevant and Appropriate Requirements (ARAR) Analysis Applicable or relevant and appropriate requirements (ARARs) are federal and state environmental statutes, regulations, and standards. Applicable requirements are federal or state laws or regulations that specifically address a hazardous substance, pollutant, contaminant, removal action, or location. Relevant and appropriate requirements that, while not “applicable,” address problems or situations sufficiently similar to those encountered that their use is well suited to the particular site. State requirements are ARARs only if they are more stringent than federal requirements. A summary of likely ARARs to be considered in this Feasibility Study are summarized in the table that follows: Requirement Description Other Information Clean Water Act (CWA) (33 USCA 125-1-1376 and 40 CFR 100-149. Federal act that establishes a system of national effluent discharge standards and ocean discharge requirements. CWA, Section 304 Establishes water quality criteria based on the designated or potential use of the water and designated use of the receiving waters. CWA, Section 404 Prohibits discharge of dredged or fill material into wetlands without a permit. US Army Corps of Engineers regulates activities that may physically alter the waters of the United State. Safe Drinking Water Act (SDWA)/ California Code of Regulations, Title 22 Establishes primary and secondary drinking water standards. California sets drinking water standards based on Federal SDWA Clean Air Act (42 USC 7401-7642, 40 CFR 50 – 69) Identifies categories of industrial sources and treatment standards. Establishes primary and secondary ambient air standards. States develop implementation plans for attainment of the standards. May be applicable or relevant and appropriate depending upon the response action being considered. Impacts to air quality, if any, under local air district jurisdiction may result from the implementation of Occupational Safety and Health Act (29 CFR 1910.120 et seq.) Identifies permissible exposure limits (PELs) for inhalation or dermal exposure of workers to chemicals. When PELs are exceeded, OSHA requires the use of personal protective equipment or other methods to block exposure. Occupational Safety and Health Act (29 CFR 1910.120 et seq.) Feasibility Study Workplan 8 Requirement Description Other Information National Historic Preservation Act of 1966 (NHPA) 16 USC 470 and 36 CFR 800 Established to preserve historic properties National Historic Preservation Act of 1966 (NHPA) 16 USC 470 and 36 CFR 800 Endangered Species Act of 1973 Established to conserve endangered or threatened species Endangered Species Act of 1973 Hazardous Waste Control Act (HSC, Chapter 6.5, section 25100 et seq., 22 CCR 66260.1 et seq.) Establishes criteria for determining waste classification for the purposes of transportation and land disposal of wastes in California. Regulates treatment, storage, transportation and disposal of substances identified as hazardous. Hazardous Waste Generator Requirements (22 CCR 66262.1 et seq.) Establishes standards applicable to generators of hazardous waste. Land Disposal Restrictions (22 CCR 66268.7 et seq.) Establishes standards for treatment and land disposal of hazardous waste. Stockpiling Requirements for Contaminated Soil (HSC section 25123.3(a)(2) Establishes standards for stockpiling of non- RCRA contaminated soil California Hazardous Substances Account Act (HSC section 25340-25392) Establishes fees regarding disposal of hazardous substances and outlines process for cleanup of hazardous substance release sites. Feasibility Study Workplan 9 Requirement Description Other Information Porter Cologne Water Quality Act (23 CCR Chapter 3, Subchapter 15, WC section 13000 et seq.) Establishes the authority of the State Water Resources Control Board and Regional Water Quality Control Boards to protect water quality by identifying beneficial uses of the waters of the State, establishing water quality objectives, and regulating discharges to is Regional Water Quality Control Board Basin Plan Adopts narrative standards and permissible concentrations of organic and inorganic chemicals for surface water, groundwater, point sources and non-point sources. Establishes beneficial uses of surface waters and groundwater. NPDES Permit The State Water Resources Control Board (SWRCB), as part of the National Pollutant Discharge Elimination System (NPDES), has adopted a statewide NPDES General Permit for Stormwater Discharges Associated with Construction Activity (General Permit) to address discharges of storm water runoff from construction projects that encompass one acre or more in total acreage of soil disturbances. This would be applicable for construction activities, including demolition, clearing, grading, excavation, soil stockpiling, material storing, onsite staging, offsite staging, and other land disturbance activities. Hazardous Waste Haulers Act (22 CCR Chapter 30) Governs transportation of hazardous materials in California. Safe Drinking Water and Toxic Enforcement Act (Proposition 65) (22 CCR section 12000 et seq.) Requires public warnings of potential exposure to suspected carcinogens and reproductive toxins. California Occupational Health and Safety (8 CCR 5192) Requires workers involved in hazardous substance operations associated with cleanup of sites perform the cleanup operations in accordance with Cal OSHA health and safety requirements. Applicable requirement for all workers who can come into contact with contaminated media at the Site Feasibility Study Workplan 10 Requirement Description Other Information California Fish and Game Code (sections 1601-1607 and 5650) Regulates activities that involve construction within stream channels to assure protection of fish and wildlife. Prohibits discharges to waters of the State that may cause adverse effects to fish, plant or bird life. Tahoe Regional Planning Agency Ordinances Governing Exterior Lighting, Land Use Coverage, Building Height/Scenic Resources and Noise Limits exterior lighting, impervious coverage of property, height and aesthetics of buildings, and the amount of noise generated during certain times of day as defined by Community Noise Equivalency Levels (CNEL).