NAPL Quick Tips: A Primer on Hydrocarbon Sheens
25
Hydrocarbon Sheens February 10, 2016 NAPL Quick Tips by Caron Koll, Consultant
-
Upload
antea-group -
Category
Environment
-
view
621 -
download
1
Transcript of NAPL Quick Tips: A Primer on Hydrocarbon Sheens
Hydrocarbon Sheens
February 10, 2016
NAPL Quick Tips by Caron Koll, Consultant
2
• Why we are concerned about sheens from subsurface petroleum releases?
• What is a sheen?• What are the misperceptions
about sheens?• How are sheens generated?
Learning Objectives
Antea USA, Inc.
Regulatory Drivers
4
Under the CLEAN WATER ACT 40 CFR Section 311 Oil and Hazardous Substances Part 110 • No discharge to surface water resulting
in: Film Sheen or Discoloration
• Required actions Notify National Response Center Remove Mitigate Prevent
Clean Water Act
Antea USA, Inc.
5
• Fines• Violations • Aesthetics• Negative Public Media
Attention• Brand
Potential Consequences
Antea USA, Inc.
Sheen Misconceptions
7
Misconceptions by regulatory and regulated community regarding the transport mechanisms of hydrocarbon from upland subsurface to surface water creating a sheen can result in costly and/or ineffective remedial actions.
Remedial Consequences of Misconceptions
Antea USA, Inc.
• Sheet Pile Walls• Hydraulic Containment• River Relocation• Long Term Boom Management • Excessive Monitoring • Excavation
8
• A thin layer of non-miscible phase resting on surface water
• May be liquid, waxy semi-solid or Petroleum Sheen solid material
• Less dense than water• Biogenic sheens derived from the breakdown
of natural organic material• “Petroleum” sheens derived from crude or
refined petroleum
What is a Sheen?
Antea USA, Inc.
9
Fact – When NAPL subsurface is historic and no longer an ongoing source, NAPL is most likely no longer migrating. A sheen from NAPL could migrate but the mass of NAPL is most often stable.
Myth – NAPL migration is the source of sheens from subsurface soils to water body.
Myth #1
Antea USA, Inc.
Sale T. and Lyverse M. 2014., Courtesy of Chevron U.S.A. Inc. “Sheens Associated with Subsurface Petroleum Releases – Current Knowledge and Best Practices”
Micro Spreading
• Petroleum sheens spread across air water interfaces until interfacial forces (γ) at the leading edge of the sheen are balanced• Spread is defined by the spreading coefficient (Sc)• Spreading may be enhanced by biosurfactants that are associated with biological
degradation
Macro Spreading
Antea USA, Inc. 11
12
Fact – Residual NAPL in soil with TPH concentrations as low as approximately 200 mg/kg can produce a sheen.
Myth – A sheen to surface water suggests a large ongoing source of NAPL with elevated concentrations in soil.
Myth #2
Antea USA, Inc.
How and Where NAPL Resides in Subsurface
Antea USA, Inc. 13
14
Fact –Sheens can travel depending on the spreading coefficient and saturation but is not a function of groundwater flow rate. Darcy’s Law applies to each fluid separately.
Myth – Sheens or NAPL in the subsurface travels as fast as or faster than groundwater.
Myth #3
Antea USA, Inc.
Sale T. and Lyverse M. 2014., Courtesy of Chevron U.S.A. Inc. “Sheens Associated with Subsurface Petroleum Releases – Current Knowledge and Best Practices”
15
Contributing factors of LNAPL Body Stability • LNAPL Composition • Soil Physical Properties• Geology/Hydrogeology
Indicators of LNAPL Body Stability • LNAPL and dissolve plume stable over time?• LNAPL not in sentinel wells?• LNAPL transmissivity less than 0. 1 ft2/day?• Source is removed or age of release ? • Spreading coefficient less than 0?
Overcoming the Myths
Antea USA, Inc.
ITRC LNAPL Training Part 1: An improved Understanding of LNAPL Behavior in the Subsurface, State of Science verse State of Practice
Indicators of Plume Stability
Sale T. and Lyverse M. 2014., Courtesy of Chevron U.S.A. Inc. “Sheens Associated with Subsurface Petroleum Releases – Current Knowledge and Best Practices”
Spreading Coefficient
Sheen GenerationMechanisms
19
• Seeps• Erosion • Ebullution
Mechanisms
Antea USA, Inc.
seeps
erosion
ebullution
20
• Residual is in soil or sediment adjacent the surface water
• Spreading Coefficient (S) is positive • Mostly occur intermittently at low tide or
falling river stage• After a significant rain event or snow melt• Horizontal orientation
Seeps
Antea USA, Inc.
21
• Residual present in soil along the shore or bank
• Physical disturbance of soil or sediment– wave action ice scour flood river stages extreme head difference behind a
bulkhead wall
Erosion
Antea USA, Inc.
22
• Natural degradation produces gases • Upward vertical migration of gas through
the air/water interface in sediment• Observed to occur during rising water levels
after a low water stage• One bubble triggers multiple
Ebullition
Antea USA, Inc.
23
Upcoming NAPL sheen series presentation quick tips topics • Sheen forensics sampling for source
evaluation• Measuring spreading coefficients and other
helpful NAPL characteristics• Innovative sustainable shoreline sheen
remedy solutions • Calculating life expectancy for sheen
remedies• Biodiversity and importance of groundwater
surface water interface – Hyproheic Zone
Upcoming Quick Tips
Antea USA, Inc.
Note: This photo is for example slide master options demo only and can be swapped out for more relevant images
B E T T E R B U S I N E S S , B E T T E R W O R L D℠
Antea Group Offices
USA Headquarters5910 Rice Creek Parkway, Suite 100St. Paul, MN 55126, USAUSA Toll Free: +1 800 477 7411 International: +1 651 639 9443
BelgiumRoderveldlaan 12600 Antwerpen
ColombiaCalle 35 No. 7-25, Piso 12Bogota, DC
France29 avenue Aristide Briand - CS 1000694117 Arcueil Cedex
NetherlandsMonitorweg 291322 BK Almere
www.anteagroup.com
