ARCHIVED REPORTS_REMEDIAL INVESTIGATION REPORT 2000

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7h3adwe11&Ro1b 4.2.3 Area 21 —404 West Fremont Street(Crystal Creamery) • Significant concentrations of petroleum fuel hydrocarbons in groundwater exist at Area 21 caused by a release from a UST. The site is currently under the jurisdiction of the CVRWQCB and local oversight agency,the SJCEHD. The 1999 study conformed the results of the work performed by others, and no significant additional soil or groundwater contamination has been found during that or the recent study. Long-term monitoring of groundwater by others has documented the presence of petroleum hydrocarbons in groundwater as summarized in Section 1.2.2.3. 5.0 CONTAMINANT FATE AND TRANSPORT 5.1 Potential Routes of Migration Contaminants are known to occur in soil and groundwater at the study area. Contaminants in soil can migrate to air, surface water, and groundwater. Contaminants in groundwater can migrate to surface water and possibly to air. Each pathway is discussed below. • 5.1.1 Potential Migration Pathways of Soil Contaminants Soil at the study area is known to contain metals, fuel hydrocarbons, and semivolatile hydrocarbons (polynuclear aromatic hydrocarbons, or PAHs). The most significant potential transport mechanism for these contaminants is as dust blown across and off the site during dry periods or site development activities. Contaminants can also be transported across and off the site during periods of heavy rain, when water can move across areas of contamination as sheet flow, carrying contaminants in the dissolved or solid phase. Contaminants in soil can be transported in the dissolved phase from semisaturated to saturated soil, where the contaminants can then be transported via groundwater flow. This is a likely pathway for petroleum hydrocarbons in OU 2 to move through the soil column to groundwater, where hydrocarbons are found in both the free and dissolved phase. Transport is a function of 30 • 25970309.DGD 24 August 2000