Free Product (LNAPL) in a Well Debunking the Alarmist Attitude/Stigma Pertaining to Environmental Risk

Transcription

1 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

2 Debunking the stigma Quarter-Century (25-Year) Evaluation Evolution of LNAPL science Regulatory approach - LNAPLs Regulatory approach - Non-LNAPLs (i.e., all other contaminants)

3 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.)

4 in a Well Means: Monitoring Well 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

5 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!

6 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?

7 Would you Continue with the same old beliefs? Continue along the same course? Continue with the status quo? Knowing that you re wrong!

8 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!

9 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.

10 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

11 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!

12 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

13 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!

14 LNAPL beneath water table

15 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!

16 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!

17 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!

18 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)

19 Normal Water Table High Water Table LNAPL LNAPL In-well LNAPL thickness changing in response to water table fluctuations LNAPL LNAPL and Water Drainage Low Water Table

20 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)

21 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

22 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!

23 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)!

24 Science Evolution of Knowledge Van Genuchten Parameters Relative Permeability Multi-Phase Fluid Flow Pore Entry Disp. Pressure Capillary Pressure Science Transmissivity Mobility/Stability Saturation/Residual Saturation Gap Regs 1987 Regs Increasing Time (Years)

25 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

26 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)

27 Government response (U.S.) Comprehensive federal UST regulations governing UST construction, operation, monitoring and release detection requirements 40 CFR Technical Standards and Corrective Action Requirements for Owners and Operators of Underground Storage Tanks

28 Government response (U.S.) 40CFR280 requirements: Methods of release detection for tanks (f) Ground-water monitoring (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; One-eighth of an inch

29 Government response 40CFR280 requirements (Continued): Free product removal At sites where investigations under (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)

30 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!

31 Why the debate Regulators essentially connected the two requirements, and made the assumption that ⅛-inch = MEP LNAPL in Well = Unacceptable Risk = Corrective Action

32 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

33 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?

34 Sustainable performance Environmental Social Economic Sustainable Performance (balance between all three)

35 LNAPL in Well Must Recover/Remediate Timeline 1980s Yes LNAPL in A Well? No Remediate to Background Concentrations 1990s Risk-Based Corrective Action (RBCA) Monitored Natural Attenuation (MNA) 2000s RBCA with Sustainability Considerations Active Remediation

36 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!

37 Interpretation of existing regs fails to recognize that All LNAPLs are different (chemical and physical properties) LNAPL chemical/physical properties, geologic setting and land use dictate true risks LNAPL chemical/physical properties and geologic setting dictate migration potential

38 Carbon Chain Hydrocarbon Ranges for Various LNAPLs Gases Liquids C1 C4 C8 C12 C16 C20 C24 C28 <C30 Gasoline (C4 C12) Kerosene / Jet Fuel (C6 C18) Diesel / No. 2 (C8 C21) Hydraulic Oil (C18 C30) Lube Oil (C18 >C34) Crude Oil (C1 >C34)

39 LNAPLs are not created equal Light-end LNAPLs pose higher risk/toxicity than heavier ends Light-ends more soluble than heavy ends Light-ends more volatile than heavy ends Light-ends more combustible than heavy ends Yet, even light-ends pose less risk than originally anticipated!

40 Unfortunately, many regulators continue with the belief that All LNAPLs are equal The mere presence of LNAPL represents an unacceptable risk requiring active recovery The absence of LNAPL in wells means the site is clean!

41 As a result Millions of $$$ are spent on unnecessary LNAPL remediation programs Non-sustainable LNAPL remediation practices continue to be the norm Some high-risk sites are closed based on the absence of LNAPL in wells!

42 Real life non-sustainable LNAPL examples $6.3M capital cost, $1M annual O&M After 1.5 years: 40 million gallons of groundwater extracted 750,000 kwh of power consumed Enough to power 65 average size homes for a year! 300 gallons LNAPL recovered >$25K/gallon LNAPL WHY?

43 Real life non-sustainable LNAPL examples $2.2M spent 1,655,050 kwh power consumed Enough to power 140 average size homes for a year! Over 2 million pounds of CO 2 emissions Thermal oxidizer, not including power generation 3,000 gallons of LNAPL recovered WHY?

44 Real life non-sustainable LNAPL examples Diesel-powered generator to run remediation system 4,000 gallons of diesel generator fuel consumed per month Less than 50 gallons of diesel LNAPL recovered per month WHY?

45 Real life non-sustainable LNAPL examples Extracted gasoline LNAPL from 10 metres below ground and dispersed untreated gasoline vapours into residential neighbourhood ARE WE REALLY CREATING A NET BENEFIT?

46 How do we fix it? It s not the law/regulation itself, but rather the interpretation of the law/regulation that needs to change In-well LNAPL thickness should never be used as a trigger to start/stop remediation Risk-based evaluations and sustainability considerations must be incorporated into the remedial decision-making process

47 How do we fix it? We must build technically sound LNAPL Conceptual Site Models (LCSMs) and use the LCSM information as a basis for remedial decision-making (see ITRC TechReg, December 2009) Maximum Extent Practicable (MEP) must be tied to the LCSM (including risk and sustainability considerations) not in-well thickness

48 Where do we go from here Must first educate ENVIRONMENTAL CONSULTANTS on current LNAPL science/ guidance Next, educate/inform policymakers, regulators and the public in general about the gap between LNAPL science and regulations and the need to adjust

49 Where do we go from here Continue to learn, develop, and promote sustainable LNAPL management and remediation practices that provide a net benefit to all! Eventually good science prevails!

50 THANK YOU!