DENBY STORE
PINE RIDGE INDIAN RESERVATION
DENBY, SOUTH DAKOTA
March 2009
Denby
ACCOMPLISHMENTS
• Removed 5 USTs and ancillary equipment
• Conducted site investigation
• Soil and groundwater monitoring
• On-site landfarming of 200 yd3 of PCS
• Closure of landfarm
EPA Region 8 performed this work in partnership with
the Oglala Sioux Tribe.
PLANNED ACTIVITIES/
FUTURE STRATEGIES
• Conduct a chemical oxidation pilot study
• Design and implement subsequent in-situ chemical
oxidation (ISCO) injection events
• Groundwater monitoring
SITE HISTORY
The former Denby Store operated as a gasoline station,
post office and grocery store. In 1996, an initial investi-
gation to assess soil and ground-water at the site was con-
ducted by South Dakota Department of Environmental
and Natural Resources (SDDENR) at the site prompted
by reports of petroleum odors in the domestic water
supply at the onsite residence of the store owner. As a
result of the investigation, six monitoring wells (MWs)
were installed and sampled along with the on-site
domestic well. The on-site domestic water supply well
was first charcoal filtered then plugged and abandoned.
The ambient air was screened in the store, residence and
adjacent property buildings using a PID, charcoal tubes
with low flow pumps and a combustible gas indicator.
Five underground storage tanks (USTs) were removed
from the site in 1997 by EPA and the Oglala Sioux
Tribe. In 1998, EPA performed additional investigations
at the site including: resampling all existing MWs and
domestic water wells; performing a soil gas survey; and
performing indoor air monitoring. In 2007, the land-
farmed soils were removed from the site.
TIME LINE
Onsite domestic well abandoned
and plugged * Carbon filters
installed in onsite domestic well
' Groundwater monitoring 6
MWs installed • Site assessment
completed
• Landfarmed soils removed from
site • Collected soil samples
from landfarmed soils
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
5 USTs removed from property
^•p
jr "*»_
(SB)
Groundwater monitoring •> Ground-
water monitoring in adjacent prop-
erty domestic wells • Soil gas surveys
of store and residence " Indoor air
surveys of store and residence and
adjacent property buildings
Groundwater
monitoring
••
DENBY STORE
EPA Region 8 UST Program Technical Contact | Mr. Raymond Faliskie | (303) 312-6124 or faliskie.raymond@epa.gov | www.epa.gov/region8/ust/
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