1. Former Waddell Compressor Station
Accelerated Site Closure Via Transmissivity Testing and Plume Stability Analysis:
Former Waddell Compressor Station
International Petroleum Environmental Conference
Denver, Colorado
October 31, 2018

2. Overview Site Location and Conditions Approach to Closure
LNAPL Transmissivity (oil/water ratio)
LNAPL Transmissivity (mobile dual phase extraction)
Groundwater stability analysis
Path Forward
Slide 2

3. Waddell Site History West Texas Permian Basin
1995 first groundwater monitoring wells installed
2009 biosparge remediation system installed
2017 additional GW delineation wells installed
2018 LNAPL transmissivity, mobile dual phase extraction, and plume stability analysis
Key points:
Site has been monitored for over 20 years and active remediation for 9
Robust dataset to perform risk-based evaluation
Site is appropriate to close using risk-based evaluation per the RRC Operator Cleanup Guidance
Slide 3

4. Site Location Slide 4 Waddell Key points: Northwest of Crane, TX
In active oil field Permian basin
Surrounded by other pipelines
No occupied structures for miles
Waddell
Source:
Slide 4

5. Texas Regulatory Setting
TCEQ provides detailed guidance for risk-based NAPL management (TRRP-32)
Extensive analysis, reporting and documentation required
Allows closure with NAPL in place on a site-specific basis
RRC does not specifically address NAPL, but does provide options…
No specific NAPL guidance like TCEQ
Allows risk-based closure within Operator Cleanup Program
Transmissivity can be a key line of evidence to stop hydraulic recovery and achieve closure
Since we’re in Texas, here are the specific programs that address site cleanup and NAPL transmissivity in Texas
Slide 5

6. Approach to Closure Perform a risk-based evaluation of the Site:
Waddell
Perform a risk-based evaluation of the Site:
Evaluate NAPL transmissivity and recoverability
Plume delineation
Plume stability
Deliver risk-based analysis to RRC to support site closure
Implement institutional controls to prevent exposure to GW exceeding RRC MCLs (work with landowner)
Achieve Site closure
Key points:
Site has been monitored for over 20 years and active remediation for 9
Robust dataset to perform risk-based evaluation
Site is appropriate to close using risk-based evaluation per the RRC Operator Cleanup Guidance
Slide 6

7. LNAPL Transmissivity
Provides quantitative value that is widely accepted and endorsed
Analogous to aquifer (groundwater) transmissivity
Tells us “how much how fast” can be recovered
Can indicate the point where hydraulic recovery is infeasible (ITRC, 2009)
Acceptable to RRC as line of evidence for closure
Key Point:
RRC may already know this, but here is a refresher on Tn concepts…background of what Tn means and why we test for it.
Hawthorne, J.M., Kirkman, A., (July 2011). Demystifying NAPL Science for the Remediation Manager. Applied NAPL Science Review (ANSR) Vol 1, Issue 7. Download at:
Slide 7

8. Multiple transmissivity measurement methods are available in ASTM E2856
We used two methods at Waddell
Measuring LNAPL Tn
Now that we have the concepts down, let’s talk about common ways to test Tn and their pros/cons depending on the setting
Three methods are most commonly used and are discussed further in the next few slides
Slide 8

9. LNAPL Transmissivity
Extensive network of monitoring wells with data beginning in 1995
Overall lateral extent of NAPL body is stable to decreasing
Performed oil/water ratio transmissivity testing at five wells in April 2018
Re-emphasize here that MW-21R is not a surprise to see LNAPL
Lateral extent of LNAPL is stable to diminishing except for MW-21R (we can explain this further if needed)
Apparent LNAPL thicknesses range from 0.16 ft (MW-17) to 1.35 ft (MW-24). That’s typical of the past few years.
MW-32
Slide 9

10. LNAPL Tn Testing (oil/water ratio)
Performed oil/water ratio testing using GEI’s patented H2AWK™
Key point:
NAPL/water ratio test is a direct way of measuring Tn and provides reliable, accurate results.
Tn calculations in accordance with ASTM E
Hydraulic recovery is not feasible based on low transmissivity
Slide 10

11. LNAPL Tn Testing (MDPE)
Landowner requested mobile dual phase extraction (MDPE)
Extracted at 3 wells in August 2018 for ~6.5 hrs each
Collected necessary data to calculate Tn
LNAPL Tn Testing (MDPE)

12. LNAPL Tn Testing (MDPE)
Well ID Tn
MW-4
2E-05
MW-11
1E-05
MW-21R
3E-02
<0.01 gals of LNAPL recovered as fluid (sheen)
~1,180 gals of water recovered
~0.5 gals of LNAPL recovered as vapor
~42 gals of propane used to destroy <1 gal LNAPL
Fairly unique circumstance where we were able to calculate transmissivity using two different methods (MDPE and NAPL/water ratio)
The results are similar and we draw the same conclusion: NAPL is not hydraulically recoverable
Tn <0.03 ft2/day
Confirms oil/water ratio results
LNAPL is not hydraulically recoverable

13. Groundwater Elevation and Quality
Class 2 aquifer
GW ~50-55 ft below ground surface
Flow is generally south
LNAPL present in some wells
BTEX and TPH detected in some wells
Key points:
GW flow is consistently to the south/southeast. Highest benzene concentrations are near the center of the Site. LNAPL presence/absence
Slide 13

14. Dissolved Phase Delineation - Benzene
MCL exceedances location in the interior of the monitoring network
MW-21R did exceed for benzene
NAPL has been observed in this well
Additional delineation well recently installed down-gradient
New well installed recently for delineation
MW-32
Slide 14

15. Dissolved Plume Stability Analysis
Stability evaluated for benzene, ethylbenzene, toluene, and TPH
Used last 10 years of data (2006 to 2017)
Groundwater Spatiotemporal Data Analysis Tool (GWSDAT) (Jones et al. 2014).
Mann-Kendall trends for individual wells
The spatiotemporal tool for plume scale analysis
Slide 15

16. Mann-Kendall Evaluation
Benzene increasing trend at MW-02, MW-05, MW-08 (near center of plume)
MW-02, MW-08 historically exhibited LNAPL
Toluene increasing trend at MW-13 (upgradient), but well below MCL
Does not represent significant deviation from historic conditions
Overall, BTEX and TPH are stable to decreasing across the site
Discuss outliers and where they’re located. And why we’re not concerned with them (i.e., they are in the middle of the Site nearby residual LNAPL)
Talk about delineation to the north and east plus 21 and 21R
Slide 16

17. Spatiotemporal Evaluation
Slide 17

18. Evaluation Summary
Delineation is complete for LNAPL and dissolved phase with one data gap:
Additional well recently installed downgradient of MW-21R
LNAPL body is laterally and vertically stable
Remaining LNAPL is not recoverable
Dissolved phase plumes are stable to decreasing
Key Points:
Discuss data gaps
Emphasize the site is well characterized
Slide 18

19. Path Forward Confirm delineation in downgradient direction (ongoing)
Shut down biosparge system (July 2018)
Deliver transmissivity and plume stability results to RRC (Fall 2018)
Finalize deed restriction with land owner (Fall 2018)
Achieve site closure (Spring 2019)
Slide 19

20. Questions? Thomas Daigle (tdaigle@geiconsultants.com)
Mike Hawthorne
Lisa Reyenga
(GEI Consultants, Denver, CO, USA)
David White
(Kinder Morgan, Houston, TX, USA)