ARCHIVED REPORTS XR0003352 - Laserfiche WebLink

Home Browse Search

6 0 POTENTIAL EXPOSURE PATHWAYS AND SENSITIVE RECEPTOR SURVEY An exposure pathway model for the site is presented in Figure 12 The primary source of exposure appears to be spills and leaks related to current and historical gasoline station operations at the site Secondary sources for exposure appear to include residual hydrocarbons in subsurface soils and dissolved hydrocarbons in the groundwater Potential exposure pathways associated with the secondary sources include volatilization to indoor and outdoor air, and the potential for dermal contact and ingestion related to subsurface construction activities at the site Given the depth to groundwater beneath the site, exposure to hydrocarbons dissolved in the groundwater, through volatilization, contact, or ingestion, appears unlikely 6.1 Potential On-site Exposure Pathways Exposure to gasoline and gasoline vapors at the active gasoline dispensing pump islands appears to represent the primary pathway for human exposure to petroleum hydrocarbons at the site Exposure to the secondary source of petroleum hydrocarbons at the site (impacted soil and groundwater beneath the site) appears limited Exposure to residual hydrocarbons in the soil might come through inhalation of compounds volatilized to either the indoor or the outdoor air The ground surface of the site is paved with concrete and asphalt These paving materials are not impervious to soil vapors, but the potential exposure risk associated with volatilization of petroleum hydrocarbon vapors to outdoor air is unlikely to represent an exposure risk Normal surface air movement (wind, etc ) is likely to dilute and remove impacted soil vapors from the site before concentrations reach risk levels Construction workers involved in excavation within the area of impacted soil could be exposed through dermal contact, accidental ingestion, or inhalation of volatilized hydrocarbons if excavations were deeper than three feet bgs However, as this is an active service station, construction activities involving excavation at the site should be performed by personnel trained in handling hazardous materials These workers should take precautions to properly check, and if necessary, ventilate excavations in the impacted areas Likewise, these workers should be taking proper measures to monitor air quality, utilize breathing respirators where appropriate, wear the proper clothing while working at the site, and wash prior to eating or drinking If properly trained workers are utilized, and proper care and attention is given to safety precautions and hygiene, the risk of exposure to construction workers appears low Dissolved petroleum hydrocarbons are present in groundwater beneath the site Since groundwater is encountered at approximately 10 feet bgs, it appears unlikely that vapors from the dissolved plume will be an exposure threat to either the indoor or outdoor air There appears to be little risk of on-site exposure to the dissolved petroleum hydrocarbons beneath the site K\USA Gasohne\0835\Reports\usa835 sem-assessment report doc Page 13 5TRATU5