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PATHWAY TO CLOSUREAT LNAPL SITESA Case Study
Railroad Environmental ConferenceOctober 2015
Daniel Dyer, CSX Transportation, Inc. Steven Aufdenkampe, Norfolk Southern Corporation Neil Ferrone, Consolidated Rail Corporation Jon Smith, Lauren Alkidas, and Colleen Barton, Arcadis
© Arcadis 2015
LNAPL may be left in place if lack of risk demonstrated
LNAPL recovery to the maximum extent practicable
LNAPL recovery to a prescriptive well thickness, e.g. less than 0.01 feet
Residual LNAPL is unacceptable
MI, TX, WI, IN, CA, MN, MA, VA, IA, PA, KS, MS
IL, OH, WV, OR IL, NV, NM, MT NJ
The Regulatory Spectrum
© Arcadis 2015
Changes in Regulatory Policy• LNAPL Presence ≠ Risk• Emphasis on LCSM
– LNAPL extent (vertical/horizontal),– Composition concerns, – Saturation concerns
• LNAPL in well ≠ Recoverable– Replaced prescriptive LNAPL
thickness with LNAPL transmissivity criterion
© Arcadis 2015
Site Background
SCALE IN FEET
0 150 300
N
CSX
NS
Conrail
YARD OFFICE
FORMER AST
FORMER ROUNDHOUSE
FORMER OIL HOUSE
FORMER FUELING
PLATFORM
UTILITY CORRIDOR
Historical LNAPL Detections
© Arcadis 2015
Petrophysical Data• Fluids
(LNAPL/Groundwater)– Density – Viscosity – Interfacial tensions
• Undisturbed Soil Cores– Locations/depths based on LIF
results– Core photography– Basic soil properties– Field/residual pore fluid
saturations– Capillary properties
© Arcadis 2015
LNAPL Transmissivity• Ideal Metric for Evaluating Recovery Potential
– ITRC (2009): 0.1 – 0.8 ft2/d– Michigan Department of Environmental Quality: 0.5 ft2/d
• ASTM Guidance (E2856) Provides Industry Best Practices
dzkgkTm
nw
z
zrn
n
nn ∫⋅
=
µρ
k = permeabilitykrn = relative permeabilityρn = LNAPL densityg = gravityµn = LNAPL viscosityz = elevation
Well
LNAPL
WaterResidual LNAPL
© Arcadis 2015
LNAPL Transmissivity Results • Field Testing at MW-
35:– May 2014 Baildown
Test: 0.14 ft2/d– January 2015 Skimming
Test: 0.04 ft2/d
• Estimates from LabData– 0.02 to 0.05 ft2/d 0
0.1
0.2
0.3
0.4
0.5
0.6
0
0.03
0.06
0.09
0.12
0.15
0.18
0 400 800 1,200 1,600 2,000
LNAP
L Tr
ansm
issi
vity
(ft2 /
d)
LNAP
L Re
char
ge R
ate
(ft3 /
d)
Elapsed Time (minutes)
January 2015 Manual Skimming Test
LNAPL Recharge RateLNAPL Transmissivity
All Results Below 0.5 ft2/d Threshold
© Arcadis 2015
LNAPL Assessment SummaryN
MW-35 Tn Results (ft2/d)
May 2014 0.14
January 2015 0.04
vn (cm/s) 3.8 x 10-6
LIF-032
Depth (ft) 5.4
Tn (ft2/d) 0.027
vn (cm/s) 3.1 x 10-7
LIF-034
Depth (ft) 9.1
Tn (ft2/d) 0.036
vn (cm/s) 6.6 x 10-7
LIF-024
Depth (ft) 3.5
Tn (ft2/d) 0.008
vn (cm/s) 2.1 x 10-6LIF-011
Depth (ft) 8.4
Tn (ft2/d) 0.005
vn (cm/s) 5.4 x 10-8
LIF-008
Depth (ft) 5.1
Tn (ft2/d) 0.002
vn (cm/s) 2.0 x 10-7
LIF-005
Depth (ft) 2.6
Tn (ft2/d) 0.050
vn (cm/s) 6.6 x 10-6
© Arcadis 2015
Utility Corridor Evaluation
UTILITY CORRIDOR
SEWER MANHOLE/CATCH BASIN
MONITORING WELL
FENCE
HISTORICAL MONITORING WELL
GROUNDWATER ELEVATION
HISTORICAL RECOVERY WELL
APPARENT GROUNDWATER FLOW DIRECTION
GROUNDWATER ELEVATION CONTOURINFERRED GROUNDWATER ELVATION CONTOUR
LEGEND
© Arcadis 2015
Vapor Intrusion Assessment• Direct Evaluation
– Soil Gas Probes– Temporary/Existing Wells
• Groundwater Sampling– May 2014
• Soil Gas Sampling – May 2014, – January 2015, & – September 2015
• No VI Exceedances
© Arcadis 2015
Investigation Conclusions
Next Step: Submit Certificate of Completion Request
Key Takeaways:• Regulatory Policy Changes Catching up with LNAPL Science• Investment in LCSM Reduces Need for Remediation• Regular/Open Communication with Regulatory Agency
• LNAPL Delineation Complete• All LNAPL Impacts On Site
• LNAPL is Not Migrating• LNAPL Recovery is Not Practical• No Offsite Groundwater Issues• No VI Concerns