FINAL SITE INSPECTION REPORT

13511352135313541355135613571358135913601361136213631364136513661367136813691370137113721373137413751376137713781379138013811382138313847.4.3 Groundwater PathwayThe TPP Memorandum indicated that groundwater was a potentially affected media, withpotential receptors located downgradient of the FUDS boundary (Shaw 2006b). No groundwaterdrinking water wells are located within the AOC, but drinking water wells are locateddowngradient of the AOC. As discussed in the TPP Memorandum, the PA/SI addressed thegroundwater pathway for the Boardman AFR; therefore, sufficient data exists to assessgroundwater. Section 2.5.3 of this SI report presents the results of the PA/SI sampling.Groundwater samples were collected within, downgradient, and cross gradient of the BoardmanAFR. A total of 25 groundwater samples were collected from the area within and surroundingthe Boardman AFR. Four of the samples were located on the Boardman AFR FUDS. Sampleswere analyzed for explosive compounds and perchlorate (see Section 2.5.3). Metals were notincluded in the PA/SI analytical suite; however, the metals associated with the munitions used atthis AOC have a low mobility. If impacts from metals in soil were present, movement to thegroundwater would not be expected. As agreed to in the TPP Memorandum, no groundwatersamples were planned or collected during the SI (Shaw, 2006b).7.4.3.1 Comparison to BackgroundAs agreed in the TPP Memorandum, no groundwater samples were collected from within theRange Complex No. 1 AOC during the SI, and no groundwater samples were collected from theAOC during the PA/SI (Shaw, 2006b). However, as discussed in Section 2.5.3, samples werecollected down and cross gradient of the AOC and FUDS. The sampling results indicated thatno explosives were detected in any groundwater sample and perchlorate was detected in 18 of 25wells sampled in the PA/SI. In the 18 samples with perchlorate detections, concentrationsranged between 0.46 g/L and 20.7 g/L. No background value for perchlorate was establishedin the PA/SI. However, based on studies completed by the ODEQ and EPA (ODEQ, 2005),perchlorate is found throughout the lower Umatilla Basin in wells located up, cross anddowngradient of the Boardman AFR. This indicates that the perchlorate detected in groundwatersamples is not originating from sources within this AOC or the Boardman AFR FUDS.7.4.3.2 Comparison to Human Health Screening ValuesThe DoD action level for perchlorate is 24 g/L. All detected concentrations of perchlorate inthe vicinity of Boardman AFR FUDS are below the DoD action level.7.4.4 Air PathwayAir is considered to be a potential pathway due to inhalation of MC in from blowing dust. Thepotential inhalation of soil particles is included in the development of health-based screeningvalues for soil.Boardman AFR Final SI Report.doc 7-5 Contract No. W912DY-04-D-0010 Delivery Order No. 003September 2007