Edwards Air Force Base - Risk Assessment

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Risk Assessment Ecological Threats Edwards Air
Force Base United States Geological
SurveyWestern Ecological Research Center
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Ecological Risk Assessment (ERA)

• Determine or predict effects of chemical
  contaminants on organisms or habitat (ecological
  receptors) at
• 469 sites

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• Three stages of ERA Process
• Pre-Scoping
• Scoping
• Predictive

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• Pre-Scoping Assessment
• Evaluate all sites based on decision matrix
  and pre-screening criteria
• Identify and document decisions to
• remove site from evaluation
• proceed with risk assessment

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All IRP Sites
If UST site, has it been remediated and is there
no ecological exposure pathway identified?
No
If homestead well site, has it been remediated?
No
No
Does the site soil contain organic COECs, or
inorganic COECs exceeding background soil levels
at less than 10 feet?
Is the groundwater depth at the site less than 25
feet?
Yes
Yes
Is the site located in an industrial or developed
area?
Yes
Is there potential for offsite transport of
contaminated soil, sediment, surface water, or
groundwater?
Yes
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• Sites classified as No Further Ecological
  Investigation (NFEI)
• REMEDIATED UNDERGROUND STORAGE TANK site with no
  potential for off-site transport of contaminants
• HOMESTEAD WELL SITE
• NO CONTAMINANTS in surface water, soil 0-10 ft,
  groundwater 0-25 ft bgs
• INDUSTRIALIZED SITE (paved or covered by
  buildings), no habitat within 500 ft of
  contamination source, no evidence of off-site
  transport of contaminants
• Contaminants detected, NO POTENTIAL FOR OFF-SITE
  TRANSPORT, and MINIMAL likelihood for EXPOSURE to
  ecological receptors

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• Sites Recommended for Full Scoping
• Not characteristic of an industrial area
  
• Organic or inorganic chemicals above
  background levels in soil (010 feet),
  groundwater (025 feet), surface water, or
  sediment
• Contiguous habitat or potential
  receptors
• Potential for off-site transport

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• Full Scoping Assessment
• Identify
• ecological receptors affected by contaminants
• contaminants of concern (COEC) for each site
• COEC fate and transport pathways
• exposure pathways from media to receptors
• Produce conceptual site model
• Recommend site for NFEI or Predictive Assessment
  

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• Full Scoping Assessment
• Documents in further detail sites with ecological
  value potentially at risk from facility-related
  chemical contamination
• Determines potential for a biological receptor to
  be exposed to an on-site contaminant
• Advances to the Predictive Assessment sites where
  a complete exposure pathway exists

Predictive Assessment Modeling - site
contaminant levels with contaminant-specific
toxicity levels known to impact ecological
receptors, in order to - predict the degree
of threat across trophic levels, and thus -
determine restoration actions necessary to
minimize or eliminate threat.
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• Pre-Scoping Summary for OUs 1, 2, 3, 4, 6, 7, 8,
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• 266 sites evaluated in Pre-Scoping
• 194 sites (73 ) listed as NFEI
• 72 sites (27 ) advanced to Full Scoping

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Draft Final Scoping ERA Work Plan Jan-01 Predict
ive ERA Work Plan Sep-01 Pre-Scoping ERA
Assessment OUs 1, 2, 3, and 6
Oct-01 Aug-04 OU 4
Dec-01 Oct-04 OU 7
Aug-03 Sep-04 OU 8
Aug-03 Oct-04 OU 9
Aug-03 Oct-04 Scoping ERA
Assessment OUs 1, 2, 3, and 6
Jul-02 Jan-03 OU 4
Apr-03 Jan-04 OU 7
Mar-04 Jun-04 OU 8
May-04 Sep-04 OU 9
Apr-04 Aug-04 Validation Study
Sep-02 ETC Publication
Sep-04
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Effects of TCE and PCE on Wild Rodents and
Reptiles
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Objectives at Contaminated and Reference Sites

• Soil Gas measures
• Population estimates of kangaroo rats using
  mark-recapture model.
• Evaluate hematology, blood chemistry, and
  pathology of tissues in 3 species of rodents and
  1 species of lizard (Uta)

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Findings

• Maximum soil gas concentrations were lt1.5 ppmv
  TCE and 0.07 ppmv PCE.
• Population estimates of kangaroo rats were
  similar at contaminated and reference sites.
• Rodent and reptile blood values and pathology
  lesions revealed no evidence of health effects
  due to exposure.

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(Some) Potential Ecological Threats
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Urban runoff, dumping, air pollution, aquifer
depletion, subsidence
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Land Subsidence and its Relation to Past and
Future Water Supplies in Antelope Valley,
CaliforniaDevin L. Galloway, Steven P.
Phillips, and Martin E. Ikehara
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LA county agriculture acreage in high desert
vegetable crops like Alfalfa, dry onions,
carrots, potatoes, peaches, grapes and nectarines
increased significantly from 9,090 acres in 1999
to 11,670 acres in 2000. Vegetable crops (mainly
carrots, potatoes, and onions) and fruit and nut
crops (mainly peaches), in proportions of 28 and
15 respectively. Kern Co, 1997 census Top 5
crop commodities orchards, cotton, hay,
vegetables, and wheat.
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Agriculture Irrigation - attractive
nuisance Effects of dust Soil Compaction Fallow
lands
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Antelope Valley 1880
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Native Species Threatened by Invasive or Nuisance
Species
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• Off Road Vehicles
• erosion, dust, compaction