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Ire-. page 2 Port of Stockton UST#3 Port Rd 13 at G Street, Stockton Soil boring B3-15 was advanced directly through the center of the UST pit to 40' I,A bgs. Ground water grabs samples collected and analyzed were from 20', 40' an 45' bgs. Dissolved total petroleum hydrocarbons as gasoline (TPHg) was r ' tected at 210;000 ugll.at 20' bgs, was.not detected at 40' bgs, and was -at230 �'de ugll at' bgs..;:'No soil samples werecc 6r oft eaormef UST pitrmay be needed to . 15, 'Additional soil data Jrom the cent, effectively calculate.the;residual icon taminantymass:and model .its future potential impact on ground water. f . a is As'with the soil°plume .the ground waters.plume of petroleum contamination o also centered on the former,UST pit as'evidenced by the surrounding monitoring wells, MW3-1, MW3-2, -3,-and MW3-6. These wells have been sampled since 1999 and only TPHg and benzene, toluene;°ethylbenzene, and xylene (BTEX) constituents have been.detected. .'No methyl tert-butyl ether (MtBE) or other fuel oxygenates.have been detected, ` On November 19, 2001, TPHg concentrations were the highest in'MW3-2 at 39;700 microgram per liter (ug/1) and as of,Nlay'15; 200 - were'at.13,000.ugll. ;f. Monitoring wells MW3n1, MW3-3,. . 1 MW3-6-have"hadTPHg concentrations as high as 11,100 ugll (MW3-1 on August 22;`2003) and, as of May 15, 2007, MW3- 3"contained TPHg at 3;500 ug11.::All but:MW3-6 are within 20 feet of boring B3-15 Y f'-. and contain dissolved,TP.Hg concentrations exponehtly lower.'than this boring indicated was present.,r,, , MW3-7 was installed approximately 200 feet southwest:of the former UST pit. No TPHg, BTEX, or oxygenates were detected in the sample.collected from this °well during the one ground Water.sampling event on May 15, 2007. Soil samples ` collected and:analyzed from 15',20', a;nd 26' bgs for this welllsoil boring also contained no detectable concentrations of TPHg, BTEX, or.oxygenates. As a recommendation, the SJCEHD suggests that instead of one large detailed - site map that contains blocks of information, your consultant use multiple iso- concentrations maps at each depth of concern for each constituent of concern. Additionally, cross sections that include ground water data and the extent of the plume should be included in the next update of the site conceptual model (SCM). A feasibility study,was included in this:combination'report that evaluated three soil remedial options and three ground water remedial options.4 All three soil remedial options were deemed to not be feasible: No feasible soil remedial option was included in the study. Additionally, all three ground water remedial w options were deemed feasible if,used together. No cost effectiveness comparison was included' in.the study: 05 : a i'