Andrew Kirkman, BP Corporation North America

LNAPL Transmissivity Application
and Estimation
Andrew Kirkman P.E.
1
Outline
LNAPL Transmissivity Overview
LNAPL Transmissivity Endpoints
Baildown Tests
Introduction to LNAPL Transmissivity
05/19/2014
2
Why use LNAPL transmissivity?
•LNAPL Thickness
− Inconsistent between hydraulic scenarios (perched, confined, unconfined)
− Inconsistent between soil types
− Poor indicator of LNAPL recovery
•LNAPL Recovery Rate More Robust Metric than LNAPL Thickness
− Need recovery system or pilot test data
− Operational variability and technology differences make it difficult to use
across technologies and/or sites
•Transmissivity
− Estimated with recovery data or field testing on monitoring wells
− Consistent across soil types
− Consistent across confined, unconfined or perched conditions
Introduction to LNAPL Transmissivity
05/19/2014
3
LNAPL Transmissivity
• LNAPL transmissivity summarizes the following
key considerations in LNAPL recovery into one metric:
Well
− LNAPL density
− LNAPL viscosity
To = ∑Ko ∆bo
LNAPL
− Soil permeability
− Magnitude of LNAPL saturation in soil
(i.e., LNAPL concentration)
− Thickness that LNAPL flows over
ρ o ⋅ g ⋅ k ⋅ k ro
Ko =
µo
Water
Introduction to LNAPL Transmissivity
05/19/2014
4
How Transmissivity Relates to Reduction of
Mobile LNAPL
Permeability
K2<K1K1>0
A Pipe
Zero
=
Permeability
Max
Permeability
As LNAPL is recovered the number of pores occupied by
LNAPL decreases, which in turn decreases its relative
permeability. This is reflected in a decrease in LNAPL
Transmissivity
Introduction to LNAPL Transmissivity
05/19/2014
5
Time Required to Recover LNAPL to
Equilibrium Thickness
•
MW-4 Confined recovers to 5 feet thickness fast than wells
33 feet of starting thickness
•
MW-18 expected to take 3 years to recover to ~35 ft of thickness
MW-1 2008
MW-4 2004 UNCONFINED
MW-18 2007
with
MW-4 2008 CONFINED
MW-6 2008
RECOVERED LNAPL THICKNESS (FT)
35.0
30.0
25.0
20.0
15.0
10.0
5.0
0.0
1
10
100
1000
ELAPSED TIME (MIN)
10000
100000
~ 2 weeks
Introduction to LNAPL Transmissivity
1000000
05/19/2014
6
Gauged LNAPL Thickness Versus
Recovery - Poor Correlation
WATER ENHANCED RECOVERY AT 1 FOOT OF DRAWDOWN (GPD)
LNAPL SKIMMING RATE (GPD)
GAUGED LNAPL THICKNESS (FT)
LNAPL RECOVERY METRIC VALUE
1000
100
33.00
33.15
10
19.03
5.40
2.60
1
0.1
0.01
MW-18
MW-6
MW-4 CONFINED
MW-4
UNCONFINED
MW-1
Introduction to LNAPL Transmissivity
05/19/2014
7
LNAPL Transmissivity Versus Recovery
Good Correlation
• LNAPL transmissivity exhibits improved correlation
• LNAPL recovery rate is a function of both drawdown induced
and LNAPL transmissivity
LNAPL RECOVERY METRIC VALUE
• Skimming drawdown is controlled by equilibrium fluid levels
and soil profile
2πTs
Q=
ln( Roi / rw )
WATER ENHANCED RECOVERY AT 1 FOOT OF DRAWDOWN (GPD)
LNAPL SKIMMING RATE (GPD)
LNAPL TRANSMISIVITY (FT2/DAY)
1000
100
35
10
31
5.2
1
0.1
0.22
0.01
0.007
0.001
MW-18
MW-6
MW-4 CONFINED
MW-4 UNCONFINED
MW-1
Introduction to LNAPL Transmissivity
05/19/2014
8
LNAPL Transmissivity versus Gauged LNAPL
Thickness – Poor Correlation
• Data from multiple sites
“Scatter”
LNAPL TRANSMISSIVITY (FT2/DAY)
• LNAPL thickness for a given impact depends on hydrogeologic
scenario, soil type, variability in water table
100
10
1
0.1
0.01
0.001
0.0001
0
1
10
GAUGED LNAPL THICKNESS (FT)
Introduction to LNAPL Transmissivity
100
05/19/2014
9
Industry Efforts to Further LNAPL
Understanding
• 2006 ASTM Guide of LNAPL Conceptual Site Models
• 2009 ITRC Guide for LNAPL technology selection – includes LNAPL
transmissivity range 0.1 to 0.8 ft2/day that corresponds to closed
sites in various states
• 2011 ASTM Guide for Estimation of LNAPL Transmissivity
• API multiple tools and documents – most pertinent here LNAPL
baildown test spreadsheet and guide document
− Now Available
− search for LNAPL transmissivity on API.org
Introduction to LNAPL Transmissivity
05/19/2014
10
Goals of Standard
• Increase accuracy of calculations for LNAPL transmissivity
• Provide standardization to generate a consistent and larger database
of information
• Identify critical assumptions and best practices
• Many points are similar in recent guidance and historical such as the
importance of well development
• Include multiple methods in a single standard to provide comparison
of methods
• Methods include:
1.
Baildown/Slug Tests (Huntley, 2000)
3.
Manual Skimming Tests
2.
Recovery System Data (Charbeneau,
2007)
4.
Tracer Tests (Sale, 2007)
Introduction to LNAPL Transmissivity
05/19/2014
11
ASTM Methods; Which One
• Baildown Testing
− Gauged LNAPL thicknesses >0.5 ft
− Requires equilibrium fluid levels
• Manual Skimming Tests
− No thickness limitation
− Requires equilibrium fluid levels
Initial Site Characterization
Recovery System Evaluation
Small Radius of Influence
• Tracer Testing
− Equilibrium fluid levels
− LNAPL gradient
• Recovery System Data
− Accurate measurements of oil, water and/or air flows
− Aquifer properties – hydraulic conductivity saturated and
potentially vadose zone; hydraulic gradient
− Large radius of influence
Introduction to LNAPL Transmissivity
05/19/2014
12
So What Transmissivity Value Means
there’s a Bunch of LNAPL There
• New catastrophic release scenario’s have resulted in LNAPL
transmissivity values on the order of 80 ft2/day
• Consider the Theim Equation:
𝑄=
2𝜋𝜋𝜋
𝑅
ln (𝑟 )
e
• 80 ft2/day with skimming (~1 ft of drawdown) would result in 816
gpd
− Or recover 80% of a 700K gallon release in 2 years with 6
skimming wells that exhibited declining recovery
• LNAPL transmissivity of 0.1 skimming (~ 0.15 ft of drawdown)
would result in < 0.2 gpd
− Or recover 300 gallons in 4 years
− Total remaining plume size is < 6400 gallons
− Hydraulic recovery no longer effective in significant plume
reduction
Introduction to LNAPL Transmissivity
05/19/2014
13
LNAPL Transmissivity in Practice
Skimming LNAPL at 0.1
ft2/day results in less
than 400 GPY skimming
•
Skimming LNAPL at 5
ft2/day results in 7300
GPY skimming
0.01
1000
3.7E+05
100
3.7E+04
10
3.7E+03
1
3.7E+02
LNAPL RECOVERY RATE (GPD)
•
0.1
5
10
20
LNAPL TRANSMISSIVITY CURVES
0.1
3.7E+01
MULTI-PHASE &
VACUUM
SKIMMING
WATER
ENHANCED
ENHANCED
RANGE
SKIMMING RANGE
RECOVERY
Example Technology Drawdown Ranges
0.01
0.1
1
LNAPL DRAWDOWN (FT)
Introduction to LNAPL Transmissivity
LNAPL RECOVERY RATE (GPY)
1
3.7E+00
10
05/19/2014
14
Stop Metric Example
Introduction to LNAPL Transmissivity
05/19/2014
15
What Fraction Can Be Removed for a
Given Starting LNAPL Transmissivity
Introduction to LNAPL Transmissivity
05/19/2014
16
f -factor – Residual saturation
• Residual saturation is proportional to the maximum historical
saturation
• As LNAPL saturation goes up so does the amount left behind BUT
• The residual fraction is constant relative to the maximum historical
saturation
𝑆𝑛𝑛 = 𝑓𝑓max
General Rules of Thumb
for f-factors
Clean Sands – 0.2
Silts – 0.3
Clays – 0.4
Johnston, C. and Adamski, M. 2005
• So 30% of what is released to a silt
becomes residual
Introduction to LNAPL Transmissivity
05/19/2014
17
Decline Curve Analysis
• As volume is recovered the saturation is decreased thereby decreasing the
rate at which it can be recovered for a given drawdown
• No more volume can be recovered as Tn goes to Zero
GROUP OF WELLS
LNAPL TRANSMISSIVITY (FT2/DAY)
16
Tn= -3.49E-05Vmobile + 2.50E+01
14
12
10
8
Solve for Vmobile at Tn=0
6
Tn − 2.50E+01
=Vmobile
−3.49E−05
4
2
0
0
100,000
716,000 𝑔𝑔𝑔=Vmobile
200,000
300,000
400,000
500,000
CUMULATIVE RECOVERED LNAPL (GAL)
600,000
700,000
Introduction to LNAPL Transmissivity
800,000
05/19/2014Page 18
Using Decline Curve Analysis with
f -factor to Estimate Residual LNAPL
• 𝑆𝑛𝑛 = 𝑓𝑓𝑡𝑡𝑡𝑡𝑡
• 𝑆𝑡𝑡𝑡𝑡𝑡 = 𝑆𝑛𝑛 +𝑆𝑚𝑜𝑜𝑜𝑜𝑜
•
𝑆𝑛𝑛
𝑓
= 𝑆𝑛𝑛 +𝑆𝑚𝑚𝑚𝑚𝑚𝑚
• 𝑆𝑛𝑛 =
𝑓𝑆𝑚𝑚𝑚𝑚𝑚𝑚
1−𝑓
or
𝑉𝑛𝑛 =
• Decline Curve Yields 𝑉𝑚𝑚𝑚𝑚𝑚𝑚
𝑓𝑉𝑚𝑚𝑚𝑚𝑚𝑚
1−𝑓
• 𝑉𝑛𝑛 = ∬ 𝑆𝑛𝑛 d𝑏𝑏𝑏 = ∬ 𝑓𝑓𝑡𝑡𝑡𝑡𝑡 d𝑏𝑏𝑏 = ∬
𝑓𝑆𝑚𝑚𝑚𝑚𝑚𝑚
d𝑏𝑏𝑏
1−𝑓
Introduction to LNAPL Transmissivity
05/19/2014
19
Reversed Decline
LNAPL Transmissivity
100%
17
90%
15
80%
13
70%
60%
LNAPL Recovered
After Reaching
0.6 ft2/day
50%
40%
LNAPL
Recovered
Above LNAPL
Transmissivity
of 0.6 ft2/day
9
7
5
Remaining Volume
Above Residual
30%
11
3
1
20%
10%
-1
RESIDUAL
VOLUME
0%
0.0
1.0
2.0
3.0
ELPASED TIME (YEARS)
4.0
Introduction to LNAPL Transmissivity
LNAPL TRANSMISSIVITY (FT2/DAY)
REMAINING VOLUME (GAL)
Remaining Volume In Place
-3
5.0
05/19/2014
20
Fraction Recovered versus
LNAPL Transmissivity – Empirical Data
Residual LNAPL Fraction (unrecoverable)
>10 years - Elapsed Time
Fraction of LNAPL Beyond Proposed Endpoint Range/was not Recovered
FRACTION OF TOTAL LNAPL WITHIN MOBILE
INTERVAL PRIOR TO RECOVERY EFFORTS (%)
100%
Fraction of LNAPL Beyond Proposed Recovery Endpoint/Continued to be Recovered with Significant
Effort
Residual Fraction
90%
80%
2 years
0.6 years
0.6 years
70%
60%
Mobile Fraction
Not Recovered
50%
40%
30%
2 years
8 years
6 years
3.75 years
10%
12 years
13.5 years
11 years
2 years
20%
8 years
11 years
Recovery Time and Fraction
Beyond Endpoint
8 years
14
years
Time Until Transmissivity
11 years 2
2
of
7.5 years
0.6 ft /day (0.55 m /day)
0%
14
Well 7
14
Wells 8 - 21
Site 1
6
Well 22
2
Well 1
3.6
Well 2
10Starting1.4
4.6
1.4
LNAPL Transmissivity
Well 3
Well 4
Site 2
Well 5
Well 6
4 years
>50 years
10 years
2/day)
(ft0.0015
0.35
Wells 23 24
Well 25
Site 3
Site 4
0.0023
Introduction to LNAPL Transmissivity
05/19/2014
21
LNAPL Transmissivity – Stop/Start Metric
Residual LNAPL Fraction (unrecoverable)
Fraction of LNAPL Beyond Proposed Endpoint Range/was not Recovered
>10 years - Elapsed Time
Fraction of LNAPL Beyond Proposed Recovery Endpoint/Continued to be Recovered with Significant Effort
>10 years - Estimated Time
Fraction of LNAPL Within Proposed Endpoint Range
FRACTION OF TOTAL LNAPL WITHIN MOBILE
INTERVAL PRIOR TO RECOVERY EFFORTS (%)
100%
90%
80%
2 years
0.6 years
0.6 years
70%
10 years
60%
8 years
50%
12 years
13.5 years
40%
30%
8 years
2 years
11 years
>10 years
2 years
20%
6 years
3.75 years
10%
11 years
8 years
14 years
7.5 years
11 years
4 years
>50 years
10 years
0%
14
14
6
2
3.6
10
1.4
4.6
1.4
0.0015 0.0023
0.35
Well 5
Well 6
Wells 23 24
Well 25
Site 3
Site 4
INITIAL LNAPL TRANSMISSIVITY (FT2/DAY)
Well 7
Wells 8 - 21
Well 22
Well 1
Site 1
Well 2
Well 3
Well 4
Site 2
NOTES:
1. RECOVERABLE LNAPL VOLUMES ARE BASED ON DECLINE CURVE ANALYSIS, MASS BALANCE AND MODEL CALIBRATION
2. RESIDUAL SATURATIONS ARE BASED ON SOIL CORE ANALYSES AND/OR MODEL CALIBRATION TO FIELD DATA
3. MODEL CALIBRATION INCLUDED, SOIL AND FLUID
TYPE, AND LNAPL TRANSMISSIVITY DATA
Introduction to LNAPL Transmissivity
05/19/2014
22
How Do We Generate This Information
for Retail Sites
• Run the API LNAPL Distribution and Recovery Model (Start/Stop
Metric)
− Residual saturation, use TPH data across smear zone or f-factor
− LNAPL transmissivity
− Fluid gauging
− Soil hydraulic conductivity
− Viscosity, more for complex LNAPL mixtures, crude oils
• Decline Curve Analysis (Stop Metric)
− Requires longer-term recovery data that conforms to decline
behavior
− F-factor or other residual estimate (e.g., TPH)
• Both are conservative and only include mobile interval from start of
data/time period considered
Introduction to LNAPL Transmissivity
05/19/2014
23
LNAPL Transmissivity used to define
extent of recovery system
Large Warehouse
32 FT RADIUS
LNAPL exists in well
casing interval only
and is no longer
recharging to well
Tn = Transmissivity ft2/day
LNAPL = Thickness ft
Tn 0.10
LNAPL 13.22
Tn 3.4
LNAPL 11.42
Tn 2.8 to 8.6
LNAPL 11.43
AOS/217-D
LNAPL 0
LNAPL 0
LNAPL 0
Tn 0.10
LNAPL 3.01
LNAPL 0
LNAPL 0
Tn 2.7 to 8.3
LNAPL 13.59
Tn 3.2
LNAPL 11.44
LNAPL 8.48
Tn 3.4
LNAPL 13.69
LNAPL 0
Tn 0.003
LNAPL 0.35
Tn 0.16
LNAPL 13.1
Introduction to LNAPL Transmissivity
05/19/2014
24
Remedial Performance Application - Scenario
1
• Strong decline indicates recovery system is well representative of
capture zone
Graphics provided by
Introduction to LNAPL Transmissivity
05/19/2014
25
Remedial Performance Application - Scenario
2
• Weak decline supports using individual well measurements (e.g.,
baildown tests) to measure LNAPL transmissivity across the plume
Graphics provided by
Introduction to LNAPL Transmissivity
05/19/2014
26
Baildown Tests
• Applicable to:
− Aquifer types: confined, unconfined, perched
− Developed monitoring well
Qn Vn
• Test method:
− Remove borehole LNAPL (i.e. well plus sand pack)
Vadose
LNAPL
Groundwater
Filter Pack
sn bn
rw
Well radius – adjusted for filter
pack porosity and NAPL saturation
− Monitor LNAPL layer recovery
• Analytical options:
− Cooper-Jacob Method
− Bouwer-Rice Methodology
• Not generally applicable to
− LNAPL thicknesses <0.5 feet
− Variable water-table conditions where recharge is
long compared to changes in groundwater elevation.
Introduction to LNAPL Transmissivity
05/19/2014
27
Move to Baildown Test
Example #1
Introduction to LNAPL Transmissivity
05/19/2014
28
Baildown Test Example #1
• Results:
− Initial test required adjustment of equilibrium fluid levels based on recovery trend
− Revised analysis resulted in LNAPL Transmissivity values ranging by a factor of 2
A retest would likely provide higher certainty but results exhibit a reasonable
variability
• Thoughts:
− Based on the reference range of 0.1 to 0.8 ft2/day ( ITRC, 2009) there is a good
chance that recovery at this location will be effective
− Small variability in results will not likely change remedial decisions, order of
magnitudes can change remedial decisions
− Recovery system performance data can then be used to further evaluate the
magnitude of LNAPL Tn with appropriate design considerations
− These include LNAPL volume over time & system performance parameters can be
measured (i.e., water extraction rate, air flow, applied vacuum, pump/stinger depth)
− B-R is sensitive to the term ln(Roi/re) for baildown tests (e.g., values of 10 versus 3.9)
• However, it is a good idea to retest this well with manual skimming test or a
second baildown test if this level of accuracy is insufficient, e.g.:
− Look at well spacing and drawdown versus time to remediate
Introduction to LNAPL Transmissivity
05/19/2014
29
API Baildown
Spreadsheet
− Helps identify and eliminate borehole
recharge
− Includes methodology to analyze
constant discharge portions of confined
and perched tests
− Includes multiple graphs for data
interpretation
Generalized Bouwer and Rice (1976)
r ln (R re ) ln (s n (t1 ) s n (t ))
Tn = e
2 (− J )(t − t1 )
2
Enter early time cut-off for least-squares model fit
Timecut
0
Le/re
6.8
<- Enter or change value here
Model Results: Tn (ft2/d) = 5.07
+/-
0.13
C
1.07
R/re
ft2/d
0
100
200
300
3.95
J-Ratio
Time (minutes)
-0.157
400
500
0.0
-0.5
-1.0
• Analysis Methods
-1.5
− Bouwer-Rice
-2.0
-2.5
− Cooper-Jacob
-3.0
− CP&B
-4.0
-3.5
Natural Log of Drawdown (ft)
• Provides tool consistent with ASTM
methodology to analyze baildown tests
Coef. Of
Variation
0.02
Bouwer and Rice Model
C coefficient calculated from Eq. 6.5(c) of Butler, The Design, Performance, and
Analysis of Slug Tests, CRC Press, 2000.
Introduction to LNAPL Transmissivity
05/19/2014
30
Input Parameters for Baildown
Tests
• Input Parameters and initial considerations provide basis for
analysis decisions and affect accuracy of the analysis
• LNAPL Density
− Although the variation in density (ρr) between 0.75 g/cc and 0.9 g/cc
seems small ~ 20%
− LNAPL drawdown calculations use (1-ρr) which results in up to 127%
variation in drawdown and therefore LNAPL Transmissivity estimates.
Introduction to LNAPL Transmissivity
05/19/2014
31
Effective Well Radius
• Well casing and filter pack radius
− Discharge is proportional to the square of the effective well radius
− Discharge is 65% higher for a 4-inch well in 8.25 inch borehole versus a
2-inch well in an 8.25 inch borehole and 5% higher for a 8.25 –inch
borehole versus an 8-inch borehole
− Many historical wells do not have borehole diameter well documented
C&J Method
B&R Method
Calculated LNAPL Volume (gal)
Correct Borehole
Borehole Error
-25%
Correct
25%
Le/re
36.4
28.9
24.7
R/re
15.2
12.6
11.1
Transmissivity (ft2/day)
0.5
0.8
1
r ln(R re ) ln(sn (t1 ) sn (t ))
Tn = e
2 (− J )(t − t1 )
+25% Borehole Error
-25% Borehole Error
3.5
3.0
2.5
2.0
1.5
4πTn s j
i
Vn (ti ) = ∑
1.0
j
0.5
 2.25Tn t j
ln
2
 re S n




∆t j
0.0
2
0.0
Used with Permission from
T. Andrews
1.0
2.0
3.0
4.0
Measured LNAPL Volume (gal)
Introduction to LNAPL Transmissivity
5.0
05/19/2014
32
Filter pack volume
• Filter pack holds 67% of the LNAPL for a 2-inch well within an 8.25
inch borehole
• Removing casing volume only results in inducing less drawdown
and having to filter out borehole recharge behavior from test
Filter Pack
Static Fluid Levels
Well
Casing/Screen
Aerial View
of Well
Static fluid level
conditions
LNAPL removed Following borehole
from well casing recharge prior to
formation recharge
only
Introduction to LNAPL Transmissivity
05/19/2014
33
Considering Well Geometry Effects
• Submerged screens where LNAPL recovers
over the top of screen presents a special condition particularly for fluctuating
water tables
Exposed
Screen
Submerged Casing
Screen Recharge
• LNAPL discharge and LNAPL
Transmissivity are highly sensitive to
effective well radius
V πr ∆b
Qn = n = e n
∆t
∆t
2
i
Vn (ti ) = ∑
j
Vn1
=
Vn2 = Vn3
4πTn s j
 2.25Tn t j
ln
2
 re S n




∆t j
r ln(R re ) ln(sn (t1 ) sn (t ))
Tn = e
2 (− J )(t − t1 )
2
Occur with Confined
LNAPL
Introduction to LNAPL Transmissivity
05/19/2014
34
Well Construction
• Well screens need to extend over the entire LNAPL
mobile interval
Well 1
Well 2
•
•
Well 1 will exhibit larger
Tn than Well 2 because
saturation is variable
across mobile interval
Well
LNAPL
LNAPL saturation and
relative permeability peak
at air/LNAPL interface for
unconfined homogenous
conditions
Water
Introduction to LNAPL Transmissivity
05/19/2014
35
Equilibrium Conditions Transmissivity
Analysis
36
Key Points for Conducting &
Analyzing Baildown Tests
− Understanding equilibrium fluid levels ensures accurate
calculation of LNAPL drawdown
− Establish that in-well LNAPL thicknesses are at equilibrium: pre
test monitoring via hydrograph
− Gauge well to completion of the test not 80%
− May not be feasible at site where baildown tests require
weeks or months to recover
− Discharge versus drawdown plots derived from baildown test
data can potentially be used to supplement where equilibrium
fluid levels are not well understood
• Well Development: establishes good communication between well
and formation
Introduction to LNAPL Transmissivity
05/19/2014
37
Equilibrium Fluid Levels
• Manual removal of LNAPL is routinely conducted on wells
exhibiting gauged LNAPL thickness at sites
− Wells are gauged during monitoring events then purged with
fluid levels and volumes removed reported in routine reports
− Little understanding accompanies these data with regards to was
the LNAPL in equilibrium.
• How long does it take a well to equilibrate
MW-1 2008
MW-18 2007
MW-4 2004 UNCONFINED
MW-4 2008 CONFINED
RECOVERED LNAPL
THICKNESS (FT)
35
30
25
20
15
10
5
0
1
10
100
1,000
10,000
100,000 1,000,000
ELAPSED
TIME (MIN)
Introduction to LNAPL Transmissivity
05/19/2014
38
Using Baildown tests to Evaluate
Equilibrium Conditions
• These plots look pretty good
• Is the test complete?
0.80
0.60
0.50
0.10
Time period between
5 PM and 8 AM
0.40
0.30
0.20
0.10
0.00
0
200
400
600
800
1,000
1,200
Time (min)
• Operating facilities often present
accessibility in terms of timing
e.g., refineries and Railroads
LNAPL Well Inflow Volume (gal)
LNAPL Thickness bn (ft)
0.70
0.09
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0.00
0
200
400
600
800
1,000
1,200
Time (min)
Introduction to LNAPL Transmissivity
05/19/2014
39
Using Baildown tests to Evaluate
Equilibrium Conditions
• They are more clear when they are in semi-log form
0.80
0.70
0.60
0.50
0.40
0.30
0.20
0.10
0.00
1
10
100
Time (min)
1,000
LNAPL Well Inflow Volume
(gal)
LNAPL Thickness bn (ft)
− These indicate additional gauging is needed
0.10
0.09
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0.00
1
10
100
1,000
Time (min)
• These plots can be used where equilibrium is not be known or to
confirm equilibrium fluid levels
• Confirming is a recommended practice - ASTM
Introduction to LNAPL Transmissivity
05/19/2014
40
Using Baildown tests to Evaluate
Equilibrium Conditions
Gauged LNAPL Thickness (feet)
• In addition to baildown test data Hydrographs can be used in a
similar fashion
AIR/LNAPL INTERFACE (FT MSL)
LNAPL/WATER INTERFACE(FT MSL)
CORRECTED GROUNDWATER ELEVATION (FT MSL)
WELL SCREEN
Fine Grained
Sand
49
-11
-21
12
10
8
6
4
2
0
10
100
1000
Time Elapsed Since Last Removal (Days)
10000
DEPTH (FT BGS)
ELEVATION (FT MSL)
-1
14
1
29
9
16
69
-31
-41
-51
10/10/06
2/22/08
7/6/09
DATE
11/18/10
89
4/1/12
Introduction to LNAPL Transmissivity
05/19/2014
41
Thank you
Andrew Kirkman, P.E.

Download Report