|
-1r _v�x s� a� LU74DOJ4JJ rIr1r7 I-t-UUC
<br /> I
<br /> TABLE 1 - CHECKLIST OF REQUIRED DATA
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> C N.ar)e and Location Regal #6o3, 6425 Pacific Avenue, Stockton,San Joaquin County
<br /> 7 Gistance to production wells for municipal, domestic, agnculture,industry A well receptor survey was completed in
<br /> c^,J other uses within 2000 feet of the site, 1998 Three water supply wells within
<br /> 2,000 feet of the site have been destroyed
<br /> t Site maps, to scale, of area impacted showing locations of fcrmar and existing tank systems Three 10,000-gallon gasoline
<br /> -a✓ation contours and sample locations, bcnng and monitonng well elevation contours, USTs were removed and
<br /> ts, and nearby surface waters, buildings, streets, and subsurface utilflies, replaced in October 1988
<br /> Site maps provided
<br /> =,glres depicting Mhology(cross section), treatment system ciagrams, Lltholl gy figures show a shallow sand
<br /> aquifer overlain with silty clay sediments
<br /> - Stcckprred soil disposed off-site(quantity), An estimated 550 cubic yards of excavated soil was transported to the
<br /> Jackson Road Landflll(Sacramento County)in November 1988
<br /> ; j 5 lrlondoring wells remaining on-site, fate, Thirteen monitorfng wells remain on-sdel and off-slte The wells will be
<br /> destroyed pending site closure
<br /> bulated results of all groundwater elevations and depths to water, Groundwater elevations varyfrom 31 to 55 feet bgs,
<br /> and groundwater flow is to the eastlnortheasL
<br /> 7 Tabulated results of all sampling and analyses December 2000 maximum groundwater monitoring results in ug/l show
<br /> Detect,on limits for confirmation sampling TPNg at 7,000,benzene at 16, tolubne at 52, ethyl benzene at 260,
<br /> xyfenes at 1400, and MtBE at 38 lead was ldentiffed at 12 mgrkg fin
<br /> Lead analyses one overexcavatlon soli sample
<br /> S Concentration contours of contaminants found and those remain,og in soil The extent of soil contamination has been
<br /> rd groundwater, and both on-site and off-site derrned The lateral and vertical extent of
<br /> I Lateral and © Vertical extent of soil contamination TPNg and BTEX is defined in groundwater
<br /> Lateral and Vertical extent of groundwatercortarninatron MtBFhas been defined in the shallow
<br /> El groundwater at 1$!rg/7 in boring CPT!
<br /> Zone efmfiuence calculated and assumptions used for subsurface A SVEsystem operated from October 1991
<br /> Ed ation system and the zone of capture attained for the soil and to December 1998, and an air sparging
<br /> y %ir ,aterremediation system, system Operated from December 1997 to
<br /> Decent ber 1998 The maximum zone of
<br /> influence Is reported at 150 feet.
<br /> Y 10 ,�eporlslrnformatinn El Unaufhonzed Release Form Qr�lRs(B/91 through 1199)
<br /> +J
<br /> Welland boring logs OPAR Q FRA
<br /> Other(Overexcavabon I of Sods, 4/00,!a'd Assessment, 5/01)
<br /> 11 Best Available Technology(BA T) used or an explanation for not using SAT, Free product removal, SVEIAS to remove an
<br /> estfmatsd 99% of contaminants
<br /> 12 Reasons why background wasris Contamination remains In soil and grouriawater both on-slte and off-she
<br /> 11'ntieinable using BAT, Remaining concentrations do not present a significant threat to water quality
<br /> i
<br /> ''ess balance calculation of substance The consultant estima(es the initial mass)was approximately 62,000 pounds
<br /> E .01'sus that remaining, of TPNg, and the remaining mass determ ned from confirmation borings in
<br /> June 1997 show 212 pounds of TPNg, a 99%reduction
<br /> i Assumptions,parameters, calculations and model used in A RSCA evaluation was completed to determine the
<br /> s' assessments, and fate and transport modeling, leachability of contaminated soil left In place, and these
<br /> results were used to iectadditionalsoll excavations
<br /> r<Gtronale why conditions remaining at site will not adversely RBin ning contaminon Is stable and decreasing
<br /> fir act water quality, health, or other beneficial uses Contamination will naturally degrade
<br /> Comments Three UST's were removed and replaced fin 1988,an on-site remediation operated from 1019t until 12/98, and
<br /> }v r' roundrrater monitoring has been completed from 12188 to 12/00The srf8 was subr ltted to the Regional ecoid for closure
<br /> on 5 June 2000 Closure was not granted because the extent of contamination downgradient of existing monitonng wells
<br /> had not been determined, groundwater analyses for fuel oxygenates and fuel addrti*were not presented, and the slatus
<br /> Of Identified water supply wells was not presented Regal completed additional moniTonng and investigation activities front
<br /> 1210004101 Regel identified(he extenl of TPNg and BTEX contemrnolion, sampled and analyzed cllhesiteveed
<br /> rcundN81er salesroxygenates and additives, and dete�M7gMund
<br /> that the three wafer supplywellwlthm2,000fet estroyed The results of 12/00 samplrnp swalerplumeisstable Based antheinvestrgalicncompleted 10date8ard staff concur withSan Joaquins closure recommendation
<br /> r
<br /> I
<br />
|