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Summary of Alternatives Evaluated Assessment Criteria Evaluation and Comparison of Alternatives Questions & Answers
2
Four action alternatives:
FPS-2 Physical containment/hydraulic control + removal of NAPL
FPS-3 Physical containment/hydraulic control + treatment/removal of NAPL/DBCP Areas and Potential Source Areas
FPS-5 Physical containment/hydraulic control + treatment/removal of NAPL/DBCP Areas and Potential Source Areas + in situ treatment of shallow soil and groundwater
FPS-7 Hydraulic control + treatment of NAPL/DBCP Areas + Excavation of all soil from unsaturated zone
The remediation alternatives have common elements.
DBCP = 1,2-dibromo-3-chloropropane in situ = “in place”, in the subsurface NAPL = Non-aqueous phase liquid 3
Excavation of soil in residential neighborhood Replacement of the City water supply Groundwater extraction and treatment NAPL recovery Site restoration Groundwater monitoring Institutional controls
The remediation alternatives build up from the common elements.
NAPL = Non-aqueous phase liquid 4
Alternative Component FPS-1 FPS-2 FPS-3 FPS-5 FPS-7
Neighborhood Soil Excavation and Offsite Disposal X X X X Engineered cap (physical containment) X X X X Vertical barrier (physical containment) X X X Perimeter drain system X X X Existing NAPL/GWCS and new NAPL collection trenches
X X X X
In situ treatment/removal of NAPL X X X In situ treatment of DBCP areas X X X Treatment/removal of potential source areas X X X In situ soil treatment X In situ groundwater treatment X Excavation X Offsite disposal X Groundwater extraction wells X Lower Outwash Unit Groundwater City water supply replacement X X X X Groundwater extraction wells X X X X Removal of NAPL (collection sump) X X X X
Alternative FPS-2
DBCP = 1,2-dibromo-3-chloropropane in situ = “in place”, in the subsurface GWCS = Groundwater collection system NAPL = Non-aqueous phase liquid 5
Alternative Component FPS-1 FPS-2 FPS-3 FPS-5 FPS-7
Neighborhood Soil Excavation and Offsite Disposal X X X X Engineered cap (physical containment) X X X X Vertical barrier (physical containment) X X X Perimeter drain system X X X Existing NAPL/GWCS and new NAPL collection trenches
X X X X
In situ treatment/removal of NAPL X X X In situ treatment of DBCP areas X X X Treatment/removal of potential source areas X X X In situ soil treatment X In situ groundwater treatment X Excavation X Offsite disposal X Groundwater extraction wells X Lower Outwash Unit Groundwater City water supply replacement X X X X Groundwater extraction wells X X X X Removal of NAPL (collection sump) X X X X
Alternative FPS-3
DBCP = 1,2-dibromo-3-chloropropane in situ = “in place”, in the subsurface GWCS = Groundwater collection system NAPL = Non-aqueous phase liquid 6
Alternative Component FPS-1 FPS-2 FPS-3 FPS-5 FPS-7
Neighborhood Soil Excavation and Offsite Disposal X X X X Engineered cap (physical containment) X X X X Vertical barrier (physical containment) X X X Perimeter drain system X X X Existing NAPL/GWCS and new NAPL collection trenches
X X X X
In situ treatment/removal of NAPL X X X In situ treatment of DBCP areas X X X Treatment/removal of potential source areas X X X In situ soil treatment X In situ groundwater treatment X Excavation X Offsite disposal X Groundwater extraction wells X Lower Outwash Unit Groundwater City water supply replacement X X X X Groundwater extraction wells X X X X Removal of NAPL (collection sump) X X X X
Alternative FPS-5
DBCP = 1,2-dibromo-3-chloropropane in situ = “in place”, in the subsurface GWCS = Groundwater collection system NAPL = Non-aqueous phase liquid 7
Alternative Component FPS-1 FPS-2 FPS-3 FPS-5 FPS-7
Neighborhood Soil Excavation and Offsite Disposal X X X X Engineered cap (physical containment) X X X X Vertical barrier (physical containment) X X X Perimeter drain system X X X Existing NAPL/GWCS and new NAPL collection trenches
X X X X
In situ treatment/removal of NAPL X X X In situ treatment of DBCP areas X X X Treatment/removal of potential source areas X X X In situ soil treatment X In situ groundwater treatment X Excavation X Offsite disposal X Groundwater extraction wells X Lower Outwash Unit Groundwater City water supply replacement X X X X Groundwater extraction wells X X X X Removal of NAPL (collection sump) X X X X
Alternative FPS-7
DBCP = 1,2-dibromo-3-chloropropane in situ = “in place”, in the subsurface GWCS = Groundwater collection system NAPL = Non-aqueous phase liquid 8
Long-Term Effectiveness and Permanence
Short-Term Effectiveness
Reduction of Toxicity, Mobility, and Volume Through Treatment
Implementability
Cost
Compliance with ARARs
Overall Protection of Human Health and the Environment
State Acceptance
Community Acceptance
ARARs= Applicable or Relevant and Appropriate Requirements 9