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16 February'1999 <br /> AGE-NC:Projec_tNo. 98-0.534 =, <br /> `Page3 of-7- r f . <br /> TPH-d,'TPH-g;BTEX.and the fW additives DIPE,ETBE_,MTBE,TAMEJBA.-The waterusamples: <br /> '•' from Tanks'2'and 5'were.:analyzed for TPH-g,,BTEX:compounds and'the fiiel additives RIPE, ' <br /> - ETBE, MTBE,'TAME;TBA: <br /> TPH-d;TPH-g, BTEX and fuel additives viwere detected in'the sail'sarnples collected fromAhe UST . <br /> excavations.'TPH-g and BTEX were detected in fo ir.of the seventeen soil-samples and TPH--.d:was. : <br /> detected in one of the seventeen soil samples.analyzed from the.UST area.. _ <br /> TPH-d was detected at low concentrations in the formeri .dispen'sei area and in-thd'mid product line' <br /> trench. TPH-g and,BTEX was also detected.in the rind portion of the`product-line trench:-TPH-g and <br /> TPH-d were detected .i'n.16'-stockpile.-soil samples. $TEX,-compounds:were detected m'eleven­. <br /> ` «< <br /> stockpile soil samples analyzed <br /> Ground`water1samples'analyzed were`impacted,wrth�TPH=g,and TPH-cl at concentrations up to <br /> 77,000 micrograms per liter(12g/L)and 70;000µg/L;as well'as BTEX co"riipounds at concentration. <br /> up to 7,890:µg/L of benzene. MTBE ,►was`detected at'a maximum concentration-6f 3 100 /ig/L.by <br /> EPA method 8020:A summary of analytical results of water'samples are piesented,'in:Tables 3 and ' ' .+" • <br /> 4. <br />` 2.3. REGIONAL GEOLOGIC/HYDROGEOL LOGIC.SETTING ' x <br /> The.site is located.within'the northern Sari-Joaquin Valley which comprises,�partof the Great,Valley t <br /> geomorphic :province of;.California The San `Joaquin °Valley ,is fozmed by:•the Great,Valley.: <br /> geosyncline,_wh1ch-is a large, elongate,'nortliwest trending asymmetrical siru"e ural trough'(basin). .. <br /> It is bordered by the-Coast Ranges to the,wesi, the Klarimath Mountains and Cascade Range to the <br /> north, and the Sierra Nevada t'o the-east. This trough has'been f Ile'd with sediments derived:from - <br /> both marine and continental sources. Thickness'of the sedimentary fill ranges fromYthiri veneers `¢ <br /> along the valley.,edges to greater than 20,000-feet mn,tYie"south central portion of the valley:�T_ he <br /> sedimentary formations'ran a in age with the.older.deposits being primarily marine in':ohgin and the :w <br /> younger deposits. being primarily. continental. ConiinentaWerived 'sediment" <br /> s_:were primarily <br /> r deposited in.lacustririe, fluvial, and'alluvial environments,with sources.Being the inouritain'i-anges <br /> surrounding the-valley(Olmsted and-Davis,81.961) T e site is located do unconsolidated.and semi _v <br /> consolidafed alluvium, lake,'playa and terrace deposits of Quaternary age (California-Division of <br /> Mines and Geology,,'1977): ° {:' t 1 ; <br /> The Modesto; Riverbank and Turlock.Lake Formations-and overlying-Recenf alluvium'are the <br /> principal sources of domestic ground water rn the3 <br /> b ,500 square mile San Joaquin <br /> Valley.Ground <br /> { Water Basin(Basin:5-22) <br /> <' S ;AdrancedGeoEnviron_mental,Int. <br />