HomeMy WebLinkAbout3501 MT. VERNON AVENUE (4)Linda S. Adams
Acting Secretary for
Environmental Protection
California Regional Water Quality Control Board
Central Valley Region
Katherine Hart, Chair
1685 E Street, Fresno, California 93706
559) 445 -5116 • FAX (559) 445 -5910
http: / /www.waterboards .ca.gov /centralvalley
Mr. Nassri Jaber
3501 Mt. Vernon Avenue
Bakersfield, CA 93306
Edmund G. Brown Jr.
Governor
12 July 2011
CASE CLOSURE - UNDERGROUND STORAGE TANK RELEASE, MINIT STOP MARKET,
2900 UNION AVENUE, BAKERSFIELD, KERN COUNTY, RB CASE NO. 5T15000857
Dear Mr. Jaber
This letter confirms the completion of a site investigation and corrective action for the
underground storage tank formerly located at the above - described location. Thank you for
your cooperation throughout this investigation. Your willingness and promptness in
responding to our inquiries concerning the former underground storage tanks are greatly
appreciated.
Based on the information in the above - referenced file and with the provision that the
information provided to this agency was accurate and representative of site conditions, this
agency finds that the site investigation and corrective action carried out at your underground
storage tank site is in compliance with the requirements of subdivisions (a) and (b) of Section
25296.10 of the Health and Safety Code and with corrective action regulations adopted
pursuant to Section 25299.3 of the Health and Safety Code and that,no further action related
to the petroleum release at the site is required.
A summary of the information in the above - referenced file is included in the Case Closure
Summary, a copy of which is enclosed. This notice is issued pursuant to subdivision (h) of
Section 25296.10 of the Health and Safety Code.
If you have any questions regarding this matter,
559) 445 -5504.
C
Pam la C. Creedon
Executive Officer
please contact Mr. John D. Whiting at
Enclosure: Case Closure Summary
cc w /enclosure' Ms. Barbara Rempel, SWRCB, UST Cleanup Fund, Sacramento
Mr. Craig Perkins, City of Bakersfield Fire Department, Bakersfield
Mr. Timothy Treloar, California Water Service, Bakersfield
City of Bakersfield Public Works Department, Bakersfield
Mr. Thomas Yoon, Bakersfield
Mr. William Lawson, E2C Remediation, LLC, Bakersfield
California Environmental Protection Agency
C4Recycled Paper
California Regional Water Quality Control Board
Central Valley Region
Katherine Hart, Chair
1685 E Street, Fresno, California 93706LindaS. Adams (559) 445 -5116 • FAX (559) 445 -5910
Acting Secretary for http: / /www. waterboards .ca.gov /centralvalleyEnvironmentalProtection
TO: Lonnie M. Wass FROM: John D. Whiting
Supervising WRC Engineer Engineering Geologist
PG No. 5951
Clay L. Rodgers
Assistant Executive Officer
0.0r;
1
Edmund G. Brown Jr.
Governor
DATE 12 July 2011 SIGNATURE: '
CASE CLOSURE SUMMARY, UNDERGROUND STORAGE TANK RELEASE, MINIT STOP
MARKET, 2900 UNION AVENUE, BAKERSFIELD, KERN COUNTY, RB CASE
NO. 5T15000857
Background Information
Site Investigation
A convenience store with retail motor fuel sales is currently and. has formerly been operated
on the subject site, which is on the northeast corner of Union Avenue and Pacific Street, in a
commercial and residential area.
During May 2000, three 10,000 - gallon gasoline underground storage tanks (USTs) and
associated dispensers and piping were removed. Two additional 5,000 - gallon gasoline USTs
discovered during the removals were abandoned in- place. Moderate to high gasoline
constituent concentrations were detected in soil samples collected beneath one 10,000 - gallon
UST and one 5,000 - gallon UST. Low to trace concentrations were also detected in samples
beneath the other USTs. The fueling facilities were later upgraded.
The Bakersfield Fire Department (Fire Department) requested assessment of the release,
which was conducted during 2001 and 2002. The investigation revealed that gasoline had
migrated to the water table. One groundwater monitoring well screened to intersect the water
table was also installed. Groundwater was encountered at 118 feet below ground surface
bgs) during well installation. The local regulatory agency referred the case to the Central
Valley Water Board by letter of 22 April 2002. Additional assessment was conducted during
2003 and 2004 to complete characterization and definition of impacted soil.
The release was characterized by high to low gasoline constituent concentrations dispersed
through a large soil volume, with some lateral spreading. The consultant estimated that
approximately 22,000 cubic yards to 125 feet bgs beneath a surface area of approximately
100 feet by 80 feet was impacted. Total petroleum hydrocarbons as gasoline (TPH -g) up to
6,300 milligrams per kilogram (mg /kg), benzene up to 58.8, and methyl tertiary butyl ether
California Environmental Protection Agency
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Minit Stop Market Case Closure Summary -2- 12 July 2011
MTBE) up to 2,800 mg /kg were detected. TPH -g above 1,000 mg /kg was extended to
approximately 115 feet bgs.
Soil and Groundwater Remediation
From April 2004 through October 2009, a soil vapor extraction (SVE) and air sparging (AS)
system removed an estimated 178,847 pounds (lbs.) or 27,945 gallons of gasoline
constituents. The unit was operated intermittently (cycled) and was operated in catalytic mode
during the last three years of operation to reduce operating costs. Removal rate had
decreased to below six lbs. per day during the last three months of operation.
Frequent sampling during the last month of operation confirmed TPH -g, toluene,
ethylbenzene, xylenes, and MTBE influent concentrations less than 1 part per million by
volume (ppmv). The consultant concluded that little or no gasoline mass remained in
subsurface soil.
Groundwater Monitoring
Four additional monitoring wells were installed during 2003 to evaluate the lateral extent of
impacted groundwater. Thirty monitoring events were conducted from February 2002 until
April 2009. Depth -to -water on -site ranged from approximately 114 to 118 feet bgs during most
of the monitoring history, and increased to approximately 124 feet bgs during the last two
events. Flow was generally toward the southeast with moderate gradients.
TPH -g was detected in groundwater beneath the source area well MW -1 from approximately
5,000 to 67,000 micrograms per liter (pg /L) until June 2004, when concentrations declined to
below 5,000 pg /L. TPH -g increased to 13,000 pg /L during October 2006, but again
decreased, and was not detected in MW -1 during the last four monitoring events. High TPH -g
concentrations (up to 68,000 pg /L) also persisted near the south site boundary in MW -3 until
October 2007, but decreased, and were not detected during the last two events.
Benzene was detected on -site at up to 3,550 pg /L during the early monitoring history, but
decreased, and was not detected in the entire monitoring network during the last eight events.
MTBE up to.74,600 pg /L was detected in MW -1; concentrations remained greater than 10,000
pg /L until June 2004. MTBE was not detected in MW -1 after December 2004, and was
generally not detected in MW -3 after May 2005.
MW -5 was installed approximately 180 feet south - southeast of MW -3. Closer installation was
prevented by a building footprint. The lack of gasoline constituent detections during the
monitoring history suggests that off -site migration was limited. TPH -g and benzene were not
detected in MW -5 and MTBE,was detected during two events prior to 2006.
Sensitive Receptors
The consultant identified six municipal wells within 2,500 of the Minit Stop Market site, but
none were within 1,800 feet. Two unlined irrigation canals are west of Union Avenue,
approximately 150 to 600 feet west of the site.
Minit Stop Market Case Closure Summary -3- 12 July 2011
Health Risk Assessment
During 2009, the consultant determined that remaining gasoline mass in soil and groundwater
was unlikely to threaten human health and recommended that the site be considered for
closure.
Public Participation and Well Destruction
On 14 January 2010, 1 mailed a pre - closure Public Notice to vicinity landowners and tenants.
Public comments were not received during the 30 -day comment period. Groundwater
monitoring and SVE wells had not been destroyed when this document was prepared, due in
part to access restrictions associated with a bankruptcy at an off -site property.
Conclusions
Gasoline constituents remaining in subsurface soil and groundwater are unlikely to impact the
present or future use of groundwater and /or human health.. Most extractable hydrocarbons
appear to have been removed by the SVE system. I estimate that as much as 1,000 lbs. of
gasoline may remain in soil as low adsorbed concentrations that are expected to naturally
degrade. Remaining effects of the release are unlikely to threaten groundwater or surface
water quality. I recommend that a standard underground tank site closure letter be mailed to
the responsible party. Groundwater monitoring and SVE wells should be destroyed in
accordance with California Well Standards and local ordinances.