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<br /> 50
<br /> aUM
<br /> FINDINGS AND RECOMMENDATIONS and
<br /> barin
<br /> =�
<br /> the data collected from our exploratory oring and
<br /> Based on well installation, s and
<br /> Hydrogeologic Properties groundsater monitarinq ro rams, the following xinulnc3
<br /> groundwater sampling P g
<br /> The water-bearing zone at the subject site appears t0 be given.
<br /> predominantly a highly plastic stiff clay to silty clay. These low recommendations may be
<br /> permeability soils typically have hydraulic conductivities (K) Findin s
<br /> ranging between 10'9 cm/sec to 10_6 cm/sec for clays and 1t cm/sec
<br /> to 10 cm/sec for silts, sandy silts', clayey sands, and till 6
<br /> Soil Investigation
<br /> ' cls to a
<br /> Groundwater Gradient a medium brown sandy
<br /> to silty Y
<br /> 2_1/2 feet below surface grade. Below this
<br /> The site is underlain by lastic clays
<br /> 1991, TECO subcontracted Martin surveying depth of approximately gray to brovan highly P
<br /> On September 4, layer are alternating layers of g Y
<br /> Consultants of Pleasanton, California (LS 5797) to survey the and silty clays to a depth of at least 20 feet•
<br /> of the well casings
<br /> monitoring well casing elevations. The top h of nine feet below
<br /> (TOC) were surveyed to the bench marcorner of the intersection of petroleum hydrocarbons were k located at the top Of thedetected at a deft
<br /> fire hydrant located at the sou surface grade in the northwestern port
<br /> of the property.
<br /> Grant Line Road and Entrada Way (City of Tracy ) C, Elevation in 5100,ppm,
<br /> elevation surveying report is included in Appendixeach of the in soil borings MW-1, SS-1, 5B-2,
<br /> the el or a TPY,g was detected at concentrations of 1100 ppm,
<br /> Surveying Report. The groundwater elevation £ 220 ppm, and 3.6 ppm
<br /> monitoring wells is shown in the table below• gS_4f respective y.
<br /> 1
<br /> yregulatory
<br /> o Soils with TP
<br /> concentrations in excess of 1000 ppm are
<br /> 10ept#r o t rouIEV-wa
<br /> requi*ed to be remediated b
<br /> �Ml l C�s3ng i V t bn typically
<br /> { � Elvtadn G �fdw� o�r ! agencies.
<br /> " of 360 ppm, 74 ppm, and
<br /> and SB , re
<br /> ct�ve y
<br /> 1 _2sps 1
<br /> xn
<br /> o TPHd was detected at concentrations
<br /> 1 boring 1 SB` '
<br /> 6.0 ppm in sol s Mw- ' ma
<br /> in excess of 100 ppmY'
<br /> { } a s 9{{ agencies
<br /> ,Oils with Ti�jj concent
<br /> rations
<br /> e ulator g
<br /> n r
<br /> be required to b •� P "`
<br /> 26 21 � s ## e remediated by regulator g
<br /> M y ,ff o �` x ? concentrations of 18�PPb� SB-2,
<br /> { 4 2B �} < o Benzene was detected at borings MW-1, SB-1r aI•d
<br /> and 150 pRb in soil Orin
<br /> n Sea LeVpl �£t) 2p�nn .resp PPbvel .i5 ph .47
<br /> EIVtod above Moa acyl Y•
<br /> qq,yy SB-1, and SB-2r
<br /> Toluene was detected at concentrations of 170,�Spb,
<br /> � t r^rvo ppb, and 620 p n soil borings tlW-1, �
<br /> r..vw s Data eft
<br /> respectively. ��PP " 45V ppb,
<br /> Groundwater Elevation
<br /> d 15 b in soil borings MW-1,
<br /> o Ethylbenxene was detected at cponcentrations o£ P
<br /> _.,-20,000 ppb, 2400 pbr
<br /> Based on the three-point problem illustrated in Figure the
<br /> and S;_4, respects elY• �P"^
<br /> lyppmSB-1, S8-2 r . 0%s fr— b
<br /> Groundwater Gradient Map, the groundwater in tha vicinity o£ the Z•4,�( concentrations of 800+6 ppb,
<br /> site flows to the north-northwest with a hydrailic gradient o£ Total Xylenes were detected a� b in soil borings MW`11
<br /> 0.0027 ft/ft- Assuming that the grnundwaterw esrelKwin hydraulwith ic3r,000 ppb, 1400 ppb, and ilve;Y•
<br /> average pore velocity equal to v Kdh/dl, 431P�- SB_1, SB-2, and�SB-4, respectti�3
<br /> conductivity and dh/d1 = hydraulic gradient, the groundwater is .j•¢Pp+�--
<br /> aced to be flowing at a rate of between 7 , 65 x of"a hydraulic s Total oil and Greto ase sailas dbarsngs SB-2oandriSBa4rons of
<br /> estim given the above range Y
<br /> 7 .65 x 10-3 ft/day, g' g
<br /> d
<br /> 56
<br /> m
<br /> in
<br /> aw,
<br /> m
<br /> and Pp
<br /> £1 34
<br /> rate of
<br /> r
<br /> oun
<br /> dw
<br /> star , PP
<br /> f the r 9
<br /> The best estimate a a e._ s ective.lY•.. ._... _.
<br /> conductivities.. Th ives an aver g re p
<br /> using an intermediate K value of l0"b cm/sec! g PAGE '22
<br /> groundwater flow rate of 7.65 x 10"5 ft/day. 175 GRANT.-LINE ROAD
<br /> PAGE 21
<br /> 275 GRANT LINE ROAD
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