|
TABQ 1 - CHECKLIST OF REQUIRED', 'TA
<br /> FOR NO FURTHER ACTION REQUESTS AT UN,b ERGROUND TANK SITES
<br /> i
<br /> Site Name and Location: Catellus Development Corp., 1325 West Webber 1Avenu'e, Stockton, San Joaquin County
<br /> 1. Distance to production wells for municipal, domestic, agriculture, A well survey was completed in 2/00,and no
<br /> industry and other uses within 2000 feet of the site; water!supply wefts were identified within 2,000
<br /> I feet of the site.
<br /> i Y
<br /> 2. Site maps, to scale, of area impacted showing locations of farmer and existing tank, systems,
<br /> excavation contours and sample locations, boring and monitoring well elevation contours,
<br /> gradients, and nearby surface waters, buildings, streets, and subsurface utilities;
<br /> i�
<br /> 3. Figures depicting lithology(cross section),;treatment system diagrams; Lithol .9 figures show silt and clay to 25 feet,
<br /> and silty sand below 25 feet. I
<br /> li
<br /> FT14. Stockpiled soil remaining on-site or off site disposal(quantity); Approxltnatelyj�1,900 cubic yards of impacted soil was
<br /> excavated and'aerated on-site. The treated soil was
<br /> 4spread out on the surface of the property in 1993. 4 i
<br /> 1 1 5. Monitoring wells remaining on-site, fate; Ten monitoring wells currently exist on-site. The wells will be destroyed
<br /> pending site closure., _--
<br /> - . 1
<br /> 6. Tabulated results of all groundwater elevations and depths to water,- Grofundwater levels vary from X to 10'below f
<br /> ground surface and flow is to the S/SW.
<br /> 0 7.Tabulated results of all sampling and analyses:
<br /> July 1999 maximum groundwater monitoring results in Ng/1 show TPHg at 2,600; TPHd at c50;BTEX at�k 260, 10, 60,and 68, respectively;MtBE
<br /> FiDetection limits for confirmation sampling at 2.4, and 1,2-DCA at 24. Total lead was identified in soil samples
<br /> Lead analyses ranging from 3 to 10 frig/kg. l
<br /> 0 8. Concentration contours of contaminants found and those remaining in soilil Contamination is confined to on-site soil I
<br /> and groundwater, and both on-site and oft-site: . and groundwater. Lateral and vertical .
<br /> Lateral and Vertical extent of soil contamination ! extent of soil and ground water
<br /> Lateral and Vertical extent of groundwater contamination �'I contamination has been defined.
<br /> 9.Zone of influence calculated and assumptions used for subsurface Groundwater extraction system, with off-
<br /> i. Y1 remediation system and the zone of capture attained for the soil and site disposal operated at impacted wells in
<br /> IIII groundwater remediation system, �R 12193P&94,and 9/94. ORC socks were yl
<br /> f added to monitoring wells in 10/96.
<br /> 10.Reports/information Unauthorized Release Form OMRs(Da}tes) 1061 —7/99 i
<br /> i
<br /> Y� Well and boring logs N�PAR Y❑ FRP Y� Other:(Submittal'of Closure Report, ERM, 10/99)
<br /> 0 11.Best Available Technology(BAT)used or an explanation for not Excavated impacted soils,groundwater extraction,
<br /> using BAT;,, e .n _. __fig- =zw�. ,ORC treatment,and monitored natural attenuation.
<br /> 12.Reasons why background was/is unattainable Approximately 210 cubic yards of impacted soils exist at Site#2. Soil
<br /> using BAT, excavation could not continue under the existing building in 1991.
<br /> Building removed in 1998.
<br /> I�
<br /> Ff 13.Mass balance calculation of substance treated The mass of impacted soil was reduced by approximately 79 percent
<br /> versus that remaining;
<br /> Consultant estimates 96,000 gallons of impacted water exists at Site
<br /> I
<br /> #1,and 136,000 gallons at Site#2. Consultant estimates seven years
<br /> for site constituents to degrade below MCLS.
<br /> Y 1
<br /> i4.Assumptions,parameters, calculations and Risk Assessment compI
<br /> leted using the Standard Guide for RBCA at�
<br /> model used in risk.assessments, and fate and Petroleum Release Sites. Consultant states that constituents in soil
<br /> transport modeling;and and groundwater are not expected to pose an unacceptable risk for
<br /> construction and industrial workers.
<br /> 15. Rationale why conditions remaining at site will Decreasing concentrations of TPHg and BTEX are documented in
<br /> not adversely impact water quality, health, or other seven years of QMRs2Shallow groundwater is not used for water
<br /> beneficial uses. supply. The site is zoned for heavy industrial use.
<br /> By — Comments: USTs were removed from the sites in 1988 to 1991. At that time, soil excavation could not continue
<br /> under the existing building at Site#2, and approximately 210 cubic yards of impacted soil remains in place. An initial
<br /> Date: well survey in 1991 identified two water supply wells within 2,000�feet of;the site. A well survey in February 2000
<br /> { r determined that one well was destroyed,and the other well was outside the 2,000-foot radius. Based on information
<br /> i
<br /> provided by the Countv, we concur with the County's closure recommendation.
<br />
|