OUSTER'S    LAST   CAMP
                NORTHERN CHEYENNE  INDIAN RESERVATION
                               BUSBY, MONTANA
                                                                         March 2009
ACCOMPLISHMENTS
• Removed 3 USTs and ancillary equipment
• Excavated and removed 3,481 yd3 of PCS
• Installed new drinking water well
• Conducted site assessments
• Installed 5 MWs
• Groundwater monitoring
• Conducted AS/SVE pilot study
• Evaluated feasibility of AS/SVE system as remedial
  strategy
• Designed full-scale AS/SVE system
EPA Region 8 performed this work in partnership with
the Northern Cheyenne Tribe and with contract support
from Avanti Corporation.

PLANNED ACTIVITIES/
FUTURE STRATEGIES
•  Install and operate AS/SVE system
•  Groundwater monitoring

SITE HISTORY
A gas station and associated store once operated at the
Custer's Last Camp (CLC) site. In 1991, the domestic
well located at CLC was found to be contaminated
with volatile organic compounds (VOC), including
                                       benzene and 1,2 DCA. In 1993 and 1994 the Montana
                                       Department of Environmental Quality (MTDEQ) con-
                                       ducted site investigations with leaking underground
                                       storage tank (LUST) Trust funds. Carbon filtration sys-
                                       tems were installed in two domestic wells. Site activities
                                       determined the source of the contamination of one of
                                       the domestic wells to be from the underground stor-
                                       age tank (UST) located in the Montana Department
                                       of Transportation (MDT) right-of-way. Four hundred
                                       fifty-five yd3 of petroleum contaminated soil (PCS) were
                                       removed from the right-of-way. However, additional
                                       sampling results indicated contamination from other
                                       sources. MTDEQ notified the owners of the CLC site
                                       that the state would no longer being funding clean-up
                                       activities at the site. EPA inspectors visited the site in
                                       1996 and CLC became eligible for federal LUST funding
                                       in 1998. The fuel dispenser, associated piping, 3 USTs
                                       and 3,481 yd3 of PCS were removed from the site in
                                       2003. Soil samples taken during the excavation activities
                                       indicated elevated concentrations of petroleum hydro-
                                       carbons in the soil. A new domestic drinking water well
                                       was installed in 2003. Two additional monitoring wells
                                       (MWs) were installed in 2004. Groundwater samples
                                       continued to show high contaminant concentrations
                                       in the vicinity of the former USTs while soil samples
                                       showed low levels of contaminants in the vicinity of the
                                       former USTs. In 2008, a site assessment was conducted
                                       at the site. Three additional MWs were installed, devel-
                                       oped and sampled. Results from the site assessment indi-
                                       cated that petroleum hydrocarbons present in the soil
                                       were limited to the vicinity of the former pump islands.
                                       An AS/SVE pilot study was designed and performed.
                                       Design work on a full-scale AS/SVE  system was com-
                                       pleted in January 2009. EPA is planning to install the
                                       remedial system in April 2009.
TIMELINE
                                                                                                  Busby


ii id LIU ii nrbL ue Let, Leu in *-i_*- uuniebLit, wen
	 Phase 1 Investigation conducted by MTDEQ
• 4 MWs installed
r Installation of passive free product recovery
system in MW-3 * Groundwater monitoring

3,481 yd3 of PCS removed and landfarmed on-s
CLC drinking water well plugged and abandoned
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

                         -Phase II Investigation •> 3 MWs installed » UST in MTD right-of-way
                          determined to be affecting 2nd drinking water well« 455 yd3 PCS
                          removed from MDT right-of-way and land farmed « Carbon filtra-
                          tion systems installed in CLC domestic well and a 2nd well
                          * Free product discovered in MW near pump island
                                                                        *- 3 USTs removed
                                                                    *- Federal LUST funding eligibility determination
                                                               - MT ceases expenditure of LUST Trust Funds
                                                                ° EPA conducts site inspection
I CUSTER'S LAST CAMP
?  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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