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4 <br /> r <br /> Mr.Fran Foikas <br /> March 21, 1988 <br /> Page 3 <br /> Total fuel hydrocarbons 343.9 mg/i <br /> Benzene 6.2 mgA <br /> Toluene 5.3 mg/1 <br /> Xylene 13.0 mg/l <br /> Source: Brown and Caldwell,November 13, 1988 <br /> It should be noted that these product concentrations were taken near the surface of the <br /> saturated zone; the groundwater collected by the extraction well will be from the aquifer <br /> to a depth of at least 100 feet. Therefore, the product concentrations in the extraction <br /> well effluent will be significantly less. <br /> Groundwater Treatment and Disposal <br /> Two methods of treatment and disposal of the pump test groundwater were evaluated. The <br /> two options are (1) collection of the groundwater with•off-site treatment and disposal, and <br /> (2)on-site treatment of the groundwater with disposal to the sewer or storm drain. <br /> ! <br /> Option 1. Collection With Off-Site Treatrnent and Disposal. This option would involve <br /> collecting the pumped groundwater, transporting the contaminated water to an approved <br /> hazardous waste treatment facility, and disposing of the treated groundwater. Due to the <br /> volume of water to- be pumped, on-site storage of 86,400 to 129,600 gallons was not <br /> considered a viable option. Therefore, a number of water transport tricks would be <br /> required. The estimated cost for this option is $240,000 to $360,000. .This cost assumes a <br /> i unit price of$2.75/gallon. <br /> 7 Option 2. On-Site Treatment With Discos l to tht Lo <br /> ., cal Sewer or Storm Drain. This <br /> option would involve routing the collected groundwater through a two-stage granular <br /> activated carbon (GAC) treatment system. A conceptual schematic of the GAC treatment <br /> system is shown on Figure 2. The system is designed such that the first-stage GAC <br /> t adsorber is capable of treating the contaminated groundwater to nondeteetable levels of <br /> total fuel hydrocarbons, benzene, toluene, and xylene. After passing through the first <br /> stage, the groundwater would be passed through a second-stage GAC adsorber as a safety <br /> measure. The treated groundwater would be discharged to the local sanitary sewer or <br /> L storm drain. The spent GAC would be removed and disposed of off site. The estimated <br /> cost to design,construct,and operate the treatment system is$25,000. <br /> Recommended Option <br /> Both options will effectively remove the petroleum product from the site; option 1 by <br /> transporting the contaminated groundwater off site for treatment and disposal, and option 2 <br /> by removing the product from_thegroundwater on <br /> _site._ Therefore,--since-option- i <br /> T -- --- significantly higher m cost ($240,000 to $360,000), compared to option 2 ($25,000), we <br /> recommend Option 2; On-site treatment with disposal to the local sanitary sewer or storm <br /> drain. The treated groundwater would have nondetectable levels of petroleum product, and <br /> BROWN AND CALDWELL <br /> 723 S SHEET SACRAMENTO,CA 95814.(W)444-0123 - - <br />