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4.0 REMEDIAL ACTION REQUIREMENTS To identify remedial action requirements and develop remedial objectives, current site condi- tions are compared to those necessary to achieve the site-specific goals outlined in the previ- ous section Where goals are achieved, remedial action is not required, conversely, where goals are not achieved, action may be required In this section, remedial action requirements are specified In October 1994, groundwater quality did not meet the secondary water quality goals at Monitoring Wells MW-2 and MW-4 At Well MW-2, TPH-g and benzene concentrations were 630 and 150 ppb, respectively, during October 1994 At Well MW-4, TPH-g concen- trations were 2,900 ppb during October 1994, however, the chromatogram for this sample exhibited a single peak with no compounds present in the benzene, toluene, ethylbenzene, and • xylenes (BTEX compounds) range indicating that this peak may have been the result of VOCs present in the sample With regard to vertical residual plume movement, any potential threat to compronuse site water quality goals, as they apply to deep groundwater bodies, appears negligible This asser- tion is based on the fact that soil samples taken for each soil boring (or well) installed to date show compliance with proposed soil-based groundwater quality goals In addition, the same attenuation mechanisms that may be stabilizing the dissolved plume in a lateral sense, work in the vertical sense It does not appear additional remedial action with regard to vertical migra- tion is necessary at this time A review of soil chemistry data (Sierra, 1994) generated from January 1987 to August 1993 Jindicate that soil-based groundwater cleanup goals have been achieved TPH-g and BTEX compounds have not been detected in any of the soil borings at the site With respect to the site public health and safety goal, there is no apparent condition that could be construed as a nuisance, and there are no risks of fire or explosion At this time, the site public health and safety goal is achieved and no associated corrective action is necessary The public health and safety goal would be compromised if use of, or exposure to, impacted groundwater was allowed i 3201357B1CAP 9 April 4, 1995