ARCHIVED REPORTS XR0009987 - Laserfiche WebLink

Home Browse Search

E osure Pathways The petroleum source has been removed and a geophysical survey did not reveal any other suspected UST locations Groundwater monitoring has shown that the plume has remained effectively stationary, in a location lust east of the traders in the driveway roughly bounded by the assumed edge location of the irrigation pipeline Some residual soil contaminants are interpreted present in the vicinity of the former tank pit, MW-3 and strata near MW-9 Boring data shows residual contaminants in the capillary fringe and occasional blebs of separate phase product occurred after the drilling, previous monitoring • shows that product was not present in most wells, wells NM-3 and MW-9 have displayed very small amounts of product_ The appearance of the product followed push borings and flowing conditions near these wells The product appearance is interpreted to be a long- term release near the wells caused by sediment disturbed by borehole flowing Possible exposure pathways at the site are by inhalation of indoor and outdoor air, and ingestion of groundwater Potential receptors could include commercial workers and trader residents The trailers are founded on stands above the ground surface and not on the ground surface A groundwater pathway is not considered for this cleanup since residential water is supplied by the City of Tracy and institutional controls preclude drilling drinking water wells on-site A one-quarter mile well search did not reveal any active water well near the site Site Cleanup Options PHS-EHD requested that Wright propose three possible cleanup options to address cleanup approach for these residual contaminants The LIST sources have been removed in 1992-1993 The geophysical survey in 2001 showed that there were no indications of a UST remaining in the area investigated On the basis of this data Wright concludes that there are no other UST's present on the basis of this data, however, there are two areas of residual soil contaminant sources which can contribute too the dissolved plume The dissolved groundwater plume has shown varying TPHG and Benzene concentrations, however, the monitoring data show that the plume is static, that is no net movement from the area bordered by Wells MW-1, 3 and 9 The edge of the plume is interpreted to extend to a point lust short of the northern property line, with some seasonal variation depending upon local ground water conditions Page 10