Loading...
081418_SouthY_obj+altsTable 1: Basin Remedial Action Objectives - DRAFT 3 Table 2: Interim Remedial Action Objectives - DRAFT 4 Summary of Response Actions To Meet Interim RAO Excludes source area remediation 1a - Limited/No Response 1b – Containment 1c – Active Restoration 1d – Ex Situ Treatment and Disposal 5 Figure 1A: Response Actions and Options Screening - Limited/No Response Actions - DRAFT Screening Comments Description Process Option Remedial Technology Groundwater General Response Action Limited/No Response No remedial action taken Baseline response action to which other actions are compared Legally enforceable land use restrictions on current and future property owners Potentially applicable for well siting restrictions in conjunction with other process options Includes California Division of Drinking Water (DDW) oversight of public water systems Potentially applicable in conjunction with other process options Risk communications regarding use of groundwater via public notices Likely to be applicable in conjunction with other process options Natural attenuation by biodegradation, dispersion, dilution, and absorption (involves long-term monitoring and contingencies) Potentially applicable in conjunction with other process options New non-impacted production wells to supplement and/or replace existing wells New non-impacted water supply source to supplement and/or replace existing wells (includes imported water, water trades, new surface water supply, direct and indirect reuse) Potentially applicable Potentially applicable Groundwater is extracted by pumping existing wells thereby removing chemicals with groundwater Potentially applicable in conjunction with other process options See Figure 1D Potentially applicable in conjunction with other process options See Figure 1D Potentially applicable in conjunction with other process options 6 Figure 1B: Response Actions and Options Screening - Containment - DRAFT Screening Comments Description Process Option Remedial Technology Groundwater General Response Action Containment Reactive metals, such as iron filings, installed in a deep trench, with optional funnel and gate strategy Not feasible due to depth of impacted zone Existing water supply wells and/or new extraction wells provide a hydraulic barrier to reduce or prevent chemical migration in groundwater Potentially applicable for hydraulic control and for water supply in conjunction with other process options Horizontal extraction wells provide a hydraulic barrier to reduce or prevent migration of chemicals in groundwater Not feasible due to depth and thickness of aquifer, and spatial extent of plume Treated groundwater is recharged to create a hydraulic barrier and increase flow to extraction wells Potentially applicable for hydraulic control in conjunction with other process options Deep trenches with porous media to intercept and collect groundwater Not feasible due to depth of impacted zone Deep trench through or around chemically impacted zones is backfilled with low permeability soil or bentonite slurry Not feasible due to depth of impacted zone HDPE sheets installed in a deep trench to provide an impermeable wall Not feasible due to depth of impacted zone Inject low permeability grout into aquifer matrix Not feasible due to depth of impacted zone See Figure 1D Potentially applicable in conjunction with other process options See Figure 1D Potentially applicable in conjunction with other process options 7 Figure 1C: Response Actions and Options Screening - Active Restoration - DRAFT Screening Comments Description Process Option Remedial Technology Groundwater General Response Action Active Restoration Groundwater is extracted by pumping vertical wells thereby removing chemicals with groundwater Groundwater is extracted by pumping horizontal wells thereby removing chemicals with groundwater Potentially applicable in conjunction with other process options Not feasible due to depth of impacted zone Deep trenches with porous media to intercept and collect groundwater Potentially applicable in conjunction with other process options Air is introduced to the saturated zone under pressure and contaminants are transferred from liquid to gas phase Not feasible due to depth of impacted zone Not feasible due to depth of impacted zone, which impedes effective delivery Not feasible due to depth of impacted zone, which impedes effective delivery Injection of substrate to amend/augment biological respiration of contaminants Not feasible due to depth of impacted zone, which impedes effective delivery Injection of chemical oxidation reagents (e.g. hydrogen peroxide) to degrade chemicals in place Injecting or utilizing existing reduced minerals (e.g. iron) to degrade chemicals in place See Figure 1D Potentially applicable in conjunction with other process options See Figure 1D Potentially applicable in conjunction with other process options 8 Figure 1D: Response Actions and Options Screening - Ex Situ Treatment and Disposal - DRAFT Screening Comments Description Process Option Remedial Technology Groundwater General Response Action Mass transfer from liquid to vapor phase usually using countercurrent air through a packed tower Potentially applicable in conjunction with other process options Potentially applicable in conjunction with other process options Fixed or fluidized bed reactors contain aerobic or anaerobic microorganisms whereby organics are biologically assimilated and transformed Potentially applicable in conjunction with other process options Limited/No Response Oxidation reagents are combined with ultraviolet light to treat recalcitrant contaminants Advanced Oxidation Reactor Liquid-phase GAC used as adsorbent media to adsorb chemicals from liquid phase stream Potentially applicable in conjunction with other process options Chemicals are separated from water as the water is passed through semi-permeable membranes (e.g. reverse osmosis, nanofiltration, ultrafiltration, electrodialyis) Potentially applicable in conjunction with other process options Membrane Separation Active Restoration Containment Discharge to nearby surface water body under NPDES permit with ongoing monitoring and reporting Potentially applicable in conjunction with other process options Potentially applicable in conjunction with other process options Conveyance to existing sewer system for treatment and disposal by POTW Crop irrigation or impoundment for infiltration and recharge under Waste Discharge permit with ongoing monitoring and reporting Potentially applicable in conjunction with other process options Deep well injection under NPDES permit with ongoing monitoring and reporting Potentially applicable in conjunction with other process options Potentially applicable in conjunction with other process options Conveyance to existing potable water distribution system for consumption Aerobic/Anaerobic Bioreactor 9 Figure 2: Alternative 2 – Replace Wells - DRAFT Abandon existing impacted supply wells Install new deeper supply wells at existing locations Install new supply wells outside of the plume Pumping rates per water supply demand No wellhead treatment Replacement Wells Capture Envelope 10 Figure 3: Alternative 3 – Wellhead Treatment - DRAFT Install/continue wellhead treatment Pumping rates per water supply wells Optional: Optimize pumping rates for capture zones Optional: Install conveyance piping to centralized treatment facility in lieu of wellhead treatment Alternatively: Conveyance to Centralized Treatment Wellhead Treatment Capture Envelope 11 Figure 4: Alternative 4 – Mid-Plume Pump and Treat - DRAFT Install line of mid-plume extraction wells downgradient of source area, with water pumped to central treatment system. Discharge TBD. Abandon existing impacted supply wells Install new deeper supply wells at existing locations Install new supply wells outside of the plume Pumping rates per water supply demand No wellhead treatment Conveyance to Centralized Treatment Capture Envelopes Extraction Well Curtain Wall 12