Investigation Area H1 Draft Feasibility Study - PowerPoint PPT Presentation

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Investigation Area H1 Draft Feasibility Study

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Overall protection of human health and the environment ... some pickleweed which may provide habitat for the salt marsh harvest mouse ... – PowerPoint PPT presentation

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Title: Investigation Area H1 Draft Feasibility Study


1
Investigation Area H1Draft Feasibility Study
2
H1 Feasibility Study Objectives
  • Develop remediation alternatives
  • Evaluate each alternative against nine specified
    criteria
  • Overall protection of human health and the
    environment
  • Compliance with applicable and relevant and
    appropriate requirements (ARARs)
  • Long-term effectiveness and permanence
  • Reduction of toxicity, mobility, or volume
  • Short-term effectiveness
  • Implementability
  • Cost
  • State acceptance
  • Community acceptance

3
Area H1 Feasibility Study
  • Discussed in three sections following the
    Remedial Investigation format
  • Containment Area
  • Upland Areas Outside the Containment Area
  • Non-tidal Wetland Areas Outside the Containment
    Area

4
Containment Area
5
Containment Area Alternatives
  • Alternative 1-No Action
  • Alternative 2-Multilayer Cap, Institutional
    Controls, Groundwater Containment, and Landfill
    Gas Monitoring
  • Alternative 3-Removal and Disposal

6
IA H1 Landfill Remedy - Containment
  • Interim Remedy Groundwater Containment Barrier
  • Completed October 2004
  • 7,300 linear feet of slurry wall
  • Groundwater extraction/collection system
  • Extracted groundwater discharged to local POTW
  • Remedy Multilayer Cap
  • Containment for approximately 70 acres
  • Includes roughly 7 acres of disposal areas that
    are seasonal wetlands Wetland X and two smaller
    areas
  • Wetlands are isolated low value wetlands but
    contain some pickleweed which may provide
    habitat for the salt marsh harvest mouse

7
RCRA Liner Cross-Section
8
Non-RCRA Liner Cross-Section
9
Wetland Mitigation
  • A Multilayer Cap will cover non-tidal Wetland
    inside containment area
  • Wetland mitigation includes creation of new
    higher value pickleweed wetlands in the upland
    areas
  • A Wetland mitigation plan is being reviewed by
    the interested agencies and experts to develop
    final workable plan

10
Existing Seasonal Wetlands Within Containment
11
History of Wetland X
Wetland X
1970
1966
1954
12
Wetland X Vicinity Subsurface Conditions
3 inch projectile shipping containers
13
IA H1 Existing Wetlands, Anticipated Wetland Loss
(Fill) Areas, and Proposed Wetland Creation Areas
14
Containment Area Removal and Disposal
  • Includes removal of all waste and transport to
    other facilities
  • Not usually considered due to past EPA experience
    and development of presumptive remedy for
    landfills
  • Requires approximately 48,000 truckloads of waste
    to be removed from the site
  • Time to complete is years (2-3)
  • Moves waste from one area to another
  • Exposes workers to more potential hazards
  • Exposes public to waste transportation hazards

15
Comparison of Alternatives Containment Area
  • Containment and Removal meet required criteria
  • Containment is much more implementable
  • Removal creates higher short term hazards in
    handling large amounts of waste material on-site
    and trucking to final disposal facilities
  • Containment can be implemented in months not
    years
  • Containment cost is 36,775,000 versus removal
    cost of 233,000,000.

16
Upland Area
17
Upland Areas Alternatives
  • Alternative 1-No Action
  • Alternative 2-Institutional Controls, Hot Spot
    Removal, Groundwater Monitoring and 2-Foot Soil
    Cover
  • Alternative 3-Institutional Controls, Limited Hot
    Spot Removal, Groundwater Monitoring, and 2-Foot
    Soil Cover
  • Alternative 4-Institutional Controls, Upland
    Excavation and Disposal

18
Upland Hot Spots and Soil Cover (Alternative 2)
19
Upland Areas Alternative 2 - Hot Spot Removal
  • Risk based determination of hot spots
  • Hot spots include all areas with
  • Unacceptable ecological risk
  • Human cancer Risk estimate of 1x10-4
  • Areas posing a threat to groundwater
  • Exhibiting visible oil/free product

20
Upland Areas Alternative 2 - continued
  • Remaining risk for Human cancer risk would be 1x
    10-5 or better.
  • After hot spot excavation an additional 2-foot
    soil cover would be placed over the entire area
    to provide a good base for vegetation.
  • Groundwater monitoring in shallow water bearing
    zone would be conducted at the margins of the
    upland area to evaluate and ensure groundwater is
    not impacting the non-tidal wetlands.

21
Upland Hot Spots and Soil Cover (Alternative 3)
22
Upland Areas Alternative 3 - 4 Limited Hot Spot
Removal and Removal
  • Similar to alternative 2 however would remove
    only hot spots that pose a threat to
    groundwater or have visible oil/free product
  • All other actions are the same as Alternative 2
    including the 2-foot soil cover and groundwater
    monitoring.
  • Alternative 4 would remove all the Upland areas
    to a depth ranging from 2-14 feet bgs.

23
Comparison of Alternatives Upland Areas
  • Alternative 2,3, and 4 satisfy the required
    criteria
  • Alternatives 2 and 3 provide the greatest
    protection to the environment, and are preferred
    based on short- and long-term effectiveness,
    implementability, and cost
  • Alternative 4 is much more difficult to implement
    and has more severe short-term impacts due to the
    large amount of material required to be excavated
  • Alternatives 2 and 3 are the preferred remedy
    with a total cost of 6,363,000 and 5,844,000,
    respectively.

24
Non-tidal Wetland Areas
25
Non-tidal Wetland Alternatives
  • Alternative 1-No Action
  • Alternative 2-Institutional Controls, Hot Spot
    Removal, and Sediment Monitoring
  • Alternative 3-Institutional Controls and Wetland
    Excavation

26
Non-tidal Wetland Areas Alternative 2 - Hot Spot
Removal
  • Risk based determination for hot spots. Same
    definitions as in the Upland Areas
  • Three hot spots would be removed
  • One current hot spot for manganese would be
    monitored because removal would likely result in
    more harm to the wetland than the available
    threat from manganese
  • Sediment monitoring will be conducted to confirm
    that concentrations in sediment are not
    increasing to hazardous levels over time

27
Non-tidal Wetland Areas Alternative 3 - Wetland
Excavation
  • This alternative includes removal of the upper
    2-feet of sediment and surface soil.
  • Destruction of habitat would occur but
    contaminants would be removed
  • Would have a substantial short term impact on
    wetlands

28
Comparison of Alternatives Non-Tidal Wetland
Areas
  • Alternative 2 and 3 satisfy the required criteria
  • Alternative 2 provides the greatest protection to
    the environment, and is preferred based on
    short-term and long-term effectiveness,
    implementability, and cost
  • Alternative 3 provides the most long-term
    effectiveness and permanence however, it presents
    the most risk of impacts to the wetlands because
    the wetlands would essentially be removed and
    then replaced
  • Alternative 2 is the preferred remedy for the
    Non-Tidal Wetlands outside the Containment
    Barrier with a total cost of 400,000. This
    alternative removes key hot spots while
    maintaining the functional wetlands

29
Next Steps
  • Comments due on Draft FS mid-January 2005
  • Selection of the Remedy
  • Proposed Plan Public Input Design in progress
  • Remedial Action Plan/Record of Decision (RAP/ROD)
  • Public Comment
  • Target RAP/ROD Approval Date June 30, 2005
  • Remedial Action Summer/Fall 2005
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