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s DISCLAIMER Preliminary remodlation goals (PRGs)focus on common exposure pathways and may not consider all exposure pathways encountered at CERCL A/RCRA sites (Exhibit 1-1). PRG& do not aansidsr impact to groundwater or address ecological concerns. -PRGs are "effically not Intended as a (1) stand-alone deeision-making tool, (2)as ■ substriute for EPA guidance for preparing baseline risk assessments, or (3)a Nle to determine g a waste Is hazardous under RCRA. The guidance set out in this document is not final Agency action. It is not Intended, nos can it be relied upon to Create any rights enforceable by any party to litigation with the Unhod States. EPA officials may decide to follow the guidance provided herein, or set at variance with the guidance, based on an analysis of specific circumstances. The Agency also reserves the right to change this guidance at any time without public notice. l.o INTRODUCTION The Aegion IX PRG table combines current EPA toxioity values with 'standard' exposure factors to estimate concentrations in environmental media (soil, Bir, and water) that are protective of humans, including Sensitive'groups, over a lifetime. Concentrations above these levels would not automatically designate a site at, *dirty' or trigger a response action. However, exceeding a PRG suggests that further evaluation of the potential risks that may be posed by Slte contaminants is appropriate. Further evaluation may include additional sampling, consideration of ambient levels In the environment, or a reassessment Of the assumptions contained in these screening-level estimates (e.g_ appropriateness of route-to-route extrSp018tions). PRG concentrations presented in the table can be used to screen pollutants in environmental Media, trigger further investigation. and provide an initial cleanup goal fi appli0ole. When considering PRGs as preliminary goals, residential concentrations should be used for tnax m m ber►wWal uses of a properly. Industrial concentrations are included th the two as an alterative cleanup goal for soils, but it is not recommended that industrW concentrations be used for scMening alts. Before applying PRGs as screening tools or initial goals, the user of the table should consider whether the exposure pathways and exposure aoen&ft$ at the site are fully accounted for in the PRG calculation. Region IX PRG ow a"tions are tossed on exposure pathways for which fierall y accepted methods, models, end assumptions have been developed (i.e. Ingestion, derrrag contact, and k talativn) for*people 1er+d-use cenditiohs and do not consider irrspatt to groundwater or ecological receptors (sae Daveloping a Conosptual Site Model below). 2