Free Product (LNAPL) in a Well Debunking the Alarmist Attitude/Stigma Pertaining to Environmental Risk Real Property Institute of Canada (RPIC) 2012 Federal Contaminated Sites National Workshop Allstream Centre, Toronto, Ontario, Canada Keynote Presentation by: David Cushman, Conestoga-Rovers & Associates May 2, 2012
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Free Product (LNAPL) in a Well Debunking the Alarmist Attitude/Stigma
Pertaining to Environmental Risk
Real Property Institute of Canada (RPIC) 2012 Federal Contaminated Sites National Workshop
Allstream Centre, Toronto, Ontario, Canada
Keynote Presentation by: David Cushman, Conestoga-Rovers & Associates
May 2, 2012
Debunking the stigma…
Quarter-Century (25-Year) Evaluation
Evolution of LNAPL science Regulatory approach - LNAPLs Regulatory approach - Non-LNAPLs (i.e., all
other contaminants)
Free Product/LNAPL means:
LNAPL - from right to left: • NAPL – Non-Aqueous Phase Liquid (immiscible
in water; does not dissolve in water) • L – Light (less dense than water; floats on water
in an open environment) • May include pure solvents, but is mostly
recognized as oil or petroleum-related materials (fuels, lubricants, etc.)
…in a Well Means:
LNAPL present in a monitoring or test well (also referred to as an observation well or piezometer)
DOES NOT refer to LNAPL
present in a drinking water or potable water well
LNAPL
Water
Monitoring Well
Why the stigma?
The thought of LNAPL (most often gasoline) in a well is simply “offensive”
It’s explosive - gasoline in a well can lead to explosions or explosive conditions
It’s toxic - one litre of gasoline can contaminate one million litres of water
It can move - if it’s in a well, then it may move somewhere else and cause problems!
But…what would you do if…
Most of what you believed about LNAPL (behaviour, dangers, risks) turned out to be false?
Things that you thought were fact, were fiction?
Perceptions that you had relied on for years turned out to be misperceptions?
Would you…
Continue with the same old beliefs? Continue along the same course? Continue with the status quo?
Knowing that you’re wrong!
Yet that’s exactly what we do when we… Automatically assume that LNAPL in a well
poses an unacceptable risk (to human health and/or the environment)
Spend millions of dollars on unnecessary and unwarranted LNAPL cleanups
Continue to ignore the current LNAPL science and forge ahead with the status quo!
Why is this important?
Because LNAPL is one of the most prevalent, widespread, common pollutants on the planet • Transportation (planes, trains, autos, ships) • Heating and cooling • Manufacturing (hydraulics, lubricants, fuel) • Construction (hydraulics, lubricants) • Etc.
Why is this important?
Because billions of $$$ are spent on LNAPL investigations and remedial operations in North America alone
Because many LNAPL remedial programs
generate more pollution and risk than what’s being mitigated
Why is this important?
Because LNAPL remediation programs often prevent/preclude the beneficial redevelopment or re-use of real property
Because the “perception” of significant risk is most often WRONG!
LNAPL misperceptions…
LNAPL research and science over the past 25 years have taught us that most of what we thought we knew about LNAPL, is incorrect!
For example…
We believed that…
LNAPL floats on top of the water table and cannot penetrate into the water
FALSE! At most sites, the majority of LNAPL is
located beneath the water table!
LNAPL beneath water table…
We believed that…
LNAPL continues to migrate once at the water table, similar to groundwater migration
FALSE! LNAPL bodies are spatially self-limiting, and
stop migrating shortly after the release is terminated!
We believed that…
No LNAPL in wells means no LNAPL at the Site
FALSE! Often times, LNAPL will be at a site and not
show up in wells!
We believed that…
LNAPL disappearing from a well for an extended period of time (years) and then reappearing indicates a new release
FALSE! Submerged LNAPL can remain in the
formation adjacent to a well for years, without appearing in the well!
We believed that…
Decreases in in-well LNAPL thicknesses during active remediation mean that the remedial program is working
FALSE! In-well LNAPL thickness may increase or
decrease in response to a fluctuating water table (with no connection to remedial progress)
In-well LNAPL thickness
changing in response to water table fluctuations
LNAPL
LNAPL
Normal Water Table
High Water Table
LNAPL
Low Water Table
LNAPL and Water Drainage
We believed that…
With the proper technologies, all LNAPL can be hydraulically recovered from the subsurface
FALSE! On average, no more than 50% of LNAPL
can be recovered (no more than 15% in finer soils)
We believed that…
All LNAPLs result in extensive groundwater contamination
FALSE! Middle distillate and heavier LNAPLs (diesel,
fuel oil, lube oil) seldom result in significant dissolved phase impacts
We believed that…
Hydraulic recovery (pumping or skimming) of LNAPL from the subsurface results in groundwater concentrations being remediated
FALSE! Hydraulic recovery of LNAPL has little to no
effect on dissolved phase concentrations!
Knowing what we now know, why do we refuse to change…
Creatures of habit – resistant to change? Don’t believe the science? Don’t trust the science? Don’t understand the science? Blame it on the existing LNAPL laws/regs
(i.e., science has advanced, laws and regulations haven’t)!
Increasing Time (Years)
Evol
utio
n of
Kno
wle
dge
Science
Regs
1987
Regs
Science
Gap
Capillary Pressure Pore Entry Disp. Pressure
Multi-Phase Fluid Flow
Van Genuchten Parameters Saturation/Residual Saturation
Mobility/Stability
Relative Permeability
Transmissivity
From the “LNAPL” beginning… Mid 1980s - retail petroleum facilities were in
a serious state of disrepair across Canada and the U.S.
Estimates indicated that as many as 1/3 of underground storage tank (UST) systems (tank and associated piping) were leaking
Numerous retail petroleum facilities with gasoline-impacted soil and groundwater
From the beginning… Existing UST systems continued to corrode
and deteriorate, leading to additional releases to the environment
Impacts were deemed to present a significant risk to human health and the environment
Some impacts required emergency measures due to severity of risks (i.e., potential explosive situations)
Government response (U.S.)…
Comprehensive federal UST regulations governing UST construction, operation, monitoring and release detection requirements
40 CFR 280 - Technical Standards and Corrective Action Requirements for Owners and Operators of Underground Storage Tanks
Government response (U.S.)…
40CFR280 requirements: • §280.43 Methods of release detection for tanks
— §280.43(f) Ground-water monitoring — §280.43(f)(6) The continuous monitoring device or
manual methods can detect the presence of at least one-eighth of an inch of free product on top of the ground water in the monitoring wells;
— At sites where investigations under §280.62(a)(6) indicate the presence of free product, owners and operators must remove free product to the maximum extent practicable as determined by the implementing agency while continuing, as necessary, … [underline/bold added].
“Maximum Extent Practicable (MEP)”
These two requirements…
⅛-inch free product (in well) Remove free product to maximum extent
practicable (MEP)
Have been the source of much LNAPL debate for the past 25 years!
Why the debate…
Regulators essentially “connected” the two requirements, and made the assumption that ⅛-inch = MEP
LNAPL in Well = Unacceptable Risk = Corrective Action
Evolving environmental times for non-LNAPL impacts…
1980s – clean to background concentrations 1990s – added risk-based decision-making to
environmental cleanups (Risk-Based Corrective Action or RBCA)
2000s – RBCA with sustainability considerations
Sustainability… Considers risks to human health and the
environment, as well as balance between environmental, economic and social issues/performance
More than “Green”, which just considers environmental benefit after remedy selection
Does the proposed remedial action result in a net benefit, or detriment?
Sustainable performance…
Social Environmental
Economic Sustainable Performance
(balance between all three)
LNAPL in Well…Must Recover/Remediate
Remediate to Background
Concentrations
Risk-Based Corrective Action
(RBCA)
RBCA with Sustainability Considerations
Active Remediation
Monitored Natural Attenuation
(MNA)
1980s
1990s
2000s
LNAPL in A Well?
No Yes
Timeline
Due to the “perceived” threat, LNAPL in a well means that…
Good science is ignored Risk-based evaluations are ignored Sustainability considerations are ignored Costs are ignored
Proceed directly to recovery!
“Interpretation” of existing regs fails to recognize that… All LNAPLs are different (chemical and