Method Three

 SPAR Programs


The Method Three & Cumulative Risk Calculator was designed to assist consultants, potential responsible parties, and regulators in evaluating soil analytical results with respect to ADEC's 18 AAC 75 regulations.

18 AAC 75 provides four methods of evaluating analytical data against regulatory guidelines. Method one and two provide look up tables to compare analytical results versus regulatory cleanup levels. Method four involves development of a risk assessment. Method three is described below.


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What is Method Three?

Method three was developed to provide flexibility in determining alternative cleanup levels for soil and groundwater. This method allows for the use of site-specific soil data, aquifer data or both, and it also allows for the use of commercial/industrial exposure values without performing a full risk assessment under method four.

Method three provides methods of determining site-specific alternative cleanup levels for three soil exposure pathways: inhalation, ingestion, and migration to groundwater. In this web calculator, the following site-specific soil and aquifer parameters may be modified:

  • Dry bulk density
  • Total soil porosity
  • Air-filled soil porosity
  • Water-filled soil porosity
  • Average soil moisture content
  • Organic carbon content of soil
  • Aquifer hydraulic conductivity
  • Hydraulic gradient
  • Infiltration Rate
  • Aquifer Thickness
  • Source length parallel to groundwater flow

In addition, the user has the choice between selecting the residential and commercial/industrial land use scenarios.

The soil and aquifer parameter values used to develop the Department's default cleanup levels may not be reflective of soil or aquifer conditions at a particular site. Therefore, method three allows for the use of site specific data for selected parameters. The Department requires submittal of the parameters proposed for modification, the site specific values for those parameters proposed for use and a description of the basis for each site specific value prior to calculating site-specific cleanup levels.