|
'sd,.::f, rF r..`�5 hx.s=' s.L:• ,....., x••. � ,- ,� r;.. , , t,y* .!_.. r , ,:� rk _.. .yr M..:`, � c /5� TIJ,. ':� r.�;.
<br /> �Ci ���+ Qom— , ., _ •. � ''J, •I i.;_y,F,
<br /> UARWAT "R r,, : ,;,lr•
<br /> r � r G• .R O U, P, ' I N C.• J , ' ,,. ,;' " !r,•
<br /> u{ a :,pry ll, `r`.. - ,`' . kL r•. • - •r, r„ 1 - J r .� .r�S..V Ir- .�r.,� VVIR
<br /> 1:0 .INTRODUCTION
<br /> ;This Jreport'was 'prepared by 'Cle'arwater Group, 'Inc. •(Clearwater) and' presents',a4
<br /> workplan for 'the :completion of a Prel'iminarly 'Site'Assessrrieiit at-Ski Service ' rf.
<br /> . ,Station,jocated at 300 South California Street in Stockton,- .California.
<br /> 1 1 'Site-Description and Background
<br /> 'The'site'.'i5 located on the southeast corne'r .of the inter'sectibn of California 'and' '
<br /> Jr _
<br /> 1.
<br /> } ` Lafayette, Streets' in ';A commercialAndustrial 'sectiori'.'of Stockton -(Figure 1)..,f The ' ,
<br /> ,•region;i slope',is generally west towards the.Sari•joaquin River. .If is aniicipated'that w
<br /> u` groundwater flow across 'the site`'will generally range':in 'direction from' westr'to
<br /> northwesi' Mr., Mike •Infurna •of the' San,JJoaquin,County Public: Health Services, ,5F i
<br /> 'Envi,r"onmental Health' Division (PHS/EHD) indicated'.that depth to 'groundwater 'atr
<br /> ' ,��sites'approximately'114 riiile'away;`i "approxiiriately 45 `feet,beiow grade:'.
<br /> r' The:,property is'.currently,utilized as a vehicle service center. Five underground fuel
<br /> r storage 'tanks {UST's) -and: one -used oil.. 4nk were--removed from the 'site :-ui'
<br /> r,
<br /> 'November•1993.' ' The excavations remain•,open: • Gasoline and diesel 'fuiel were.
<br /> 'previously dispensed' at the,service station: The'site•Iayout including the locatiort;of
<br /> the 1former:UST's`.is-presented,-in Figure 2:.•-The results of .analysis,of Soil samples
<br /> collected during;:tank removal' activities indicated ,the' presence of-.hydrocarbons;An
<br /> the',-subsurface (=Appendix A). The':highest concentration of total petroleum.
<br /> ' rhydracarbons' as gasoline (TPHg)'detected in. the'soil samples analyzed, was. 8,500
<br /> "Aparts`per 25 million: (ppin)..: The highest ,concentrations of benzene' toluene ethyl ,
<br /> benzene, and,.total ;xylenes ..(BTEX) defected ''in the soil .samples .analyzed wv6rp, 1
<br /> h retiv
<br /> specely, not•detected less thLi ppm; b70,ppm; not',detected-less-than 25'ppm;'.
<br /> ,,- 4200p.prn:- -bne Sol l'sample ,contained 'total 'petroleum-',hydrocarbons''as.'-,.diesel, ;_
<br /> f ('FPHd) -ata',concentration of'7' .4 ppm:' 'One soil sample ,contained' ,tbtaI 'petrbleum
<br />.; hydrocarbons'as motor;oil at'a conceiiiratiori bf'r160,ppm.
<br /> `r I _ I` f; ;(, i rr i Ir. r. ..',. .r ' i r;. �' '. �J , r•Jh 1, '' "' ,I �'! i `ry r 's I tee,` ���' I>
<br /> 5' 2.0'APROPOSED'FIELD ACTIVITIES_
<br /> �r' / t I,r, . r' rA'' a :r r r. r.- r, , ' ,, ,`� r• r, t i.!• t., '
<br /> L .,'/, ,p .,r 7,-- 4., ;,`/• ,,.�t 1 r " • '_ ' - �:� t ', .'i'. .. .'r ,.'' - !': t'. �,, .1 ,.. , ..�,
<br /> In :'order to. evaluate ':the, concentration/distribiit''on - of hy'drocarbon' s. in".the
<br /> ` ; y subsurface'Clearwater recomrnerids' that 'a:preliminary'site assesment bb conducted
<br /> ,This iassessment r consists of drilling arid' ,irtst Illingr three groundwater,monitoring
<br /> wells,r'surveying wellhead.elevations' And monxtorxng J,and sampling .groundwater
<br /> from thewells., ,, f"
<br /> •.f r •,r - r it . f, t - ._. _ i✓•.� ., `, , ,
<br /> 14
<br /> 2.1 Soil;Borehole,Drillrig and,Soil:Sarnphng;' , ;'• ,,,y ,,, .i; :j ' .,. ,
<br />` Clearw_ater recommends drilling ihxee`eight-inch ,diarrieter.'soil' borings, ,designated
<br /> 4V
<br /> M -1; PMW-2 and,.PMW-3' ;(Figure,'2) '10 fe' 'I'below' first"encountered water,
<br /> I. . .r ,
<br /> D-105'WI•WORKPiAN ' 1 '' january'19; 1995!
<br /> `sf _ V. r !:!' .r.,f.• , ', • 1, ,;.ti r r. -i` r , r / J* 'r ` ''7 ..-r
<br />
|