1 National Western Center February 25, 2016 Environmental - - PowerPoint PPT Presentation

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1 National Western Center February 25, 2016 Environmental - - PowerPoint PPT Presentation

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1 National Western Center February 25, 2016 Environmental Investigations Presentation to the Citizens Advisory Committee 2 Why Conduct Environmental Investigations? Past industrial land uses may have contaminated soils and groundwater

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National Western Center Environmental Investigations

Presentation to the Citizens Advisory Committee

February 25, 2016

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Why Conduct Environmental Investigations?

  • Past industrial land uses may have contaminated soils and groundwater
  • Information needed to:
  • Protect health during construction and long-term use
  • Improve redevelopment planning and cost estimating
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Why Conduct Environmental Investigations?

  • Entire NWC Master Plan Area
  • Records review (Sanborn maps, aerial

photos, historical phone books, etc.)

  • NWSS- and City-owned properties
  • Interviews and site visits
  • Field Investigations
  • Follow-up investigations on areas of

concern

  • Groundwater
  • Vapor
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Where and How We Investigated?

Primary Study Area (NWSS and City-owned properties)

  • Interviews and site visits
  • Field Investigations
  • Monitoring wells
  • Soil Borings
  • Soil Vapor Sampling
  • Test Pits
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What We Found:

Surface soils

  • Lead in soils:
  • generally low concentrations
  • a few locations above residential cleanup levels
  • one above industrial cleanup standards
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What We Found:

Surface soils

  • Arsenic in soils:
  • Sampled 0-6”, 6-24”
  • All samples below residential cleanup levels
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What We Found:

Buried Debris:

  • Evidence of numerous old buildings (no longer

standing)

  • Extensive buried debris on western side
  • No buried asbestos waste found
  • Generally construction concern rather than

environmental

  • Monitoring wells on eastern side show little

evidence of buried debris

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What We Found:

Groundwater:

  • Perchloroethylene (PCE, or perc) plume

entering site from southeast

  • Source appears to be off-site
  • No known groundwater exposures
  • Further investigations conducted
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What We Found:

Groundwater:

  • Low levels nitrates
  • Exceeds drinking water standard, below

agricultural standard

  • No known groundwater exposures
  • Further investigations conducted
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What We Found:

Vapors:

  • Soil Vapor (PCE):
  • Detected in some borings over groundwater

plume

  • levels below concern for indoor air exposure
  • Confirmed through further investigation
  • Methane:
  • Levels of concern found near DPS bus barn
  • Several old landfills in area
  • Further investigation conducted
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What We Found:

Methane – Bus Barn:

  • Further investigations
  • Confirmed presence of methane at levels of

concern

  • Mitigation installed
  • DPS installed venting system
  • Follow-up sampling confirmed system is

working properly

  • Methane concentrations at boundary

decreased below levels of concern

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Conclusions and Next Steps

  • Surface soils – low levels of metals to be addressed during

planning/construction

  • Buried debris – address during planning/construction
  • Further investigate groundwater in southeast area
  • Ensure effective methane venting continues
  • Further characterization of existing buildings during construction planning
  • Investigation of other buildings/land during acquisition process
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