IMPROVING REMEDIATION DECISIONS AT HAZARDOUS-WASTE SITES WITH RISK-BASED GEOSTATISTICAL ANALYSIS

The soil-related cancer risk of a hazardous waste site is usually boun ded by selecting an upper confidence limit on the mean concentration v alue for each carcinogen and using these levels to define exposures, w hich are then combined with cancer potency factors to define risk. We suggest it is more appropriate to define cancer risk for each sample t aken at the site. This sample-specific risk can be used in a geostatis tical procedure to produce maps of block-specific risk at the site. Wh en combined with models of site utilization, a quantity, which we call ''riskiness,'' can be developed to define the risk contribution of th e k(th) site location to a particular exposure scenario. We demonstrat e the derivation of block-specific risk and show how bath this quantit y and riskiness can be displayed graphically to aid communication with stakeholders and decision making regarding actual remediation strateg ies.