1. AUTOMATED BAILDOWN TESTS
Better, Cheaper, Safer Data
Andy Pennington & Jonathon Smith
November 2015

2. LNAPL Baildown Tests – Easy, Right?
Baildown tests are hard –
Use field time efficiently
Document complete NAPL recovery
Collect enough data to identify confined or perched conditions
And do it all safely!

3. Manual Data Collection Problems
Missing key data overnight
Cutting test short for budget/efficiency reasons
Sparse data for very fast recovering wells
Repeated access to well locations
“Things got back to equilibrium sometime before 7 AM…” Should I stay out here another day to get one more measurement?” “I’m gauging as fast as I can!” “I need to block off this roadway for 5 minutes every hour…”
Good Data Supports Risk-Based LNAPL Management

4. Improving the Measurement Concept
Less Staff Time in High-Risk Areas
Can we build a datalogger to measure LNAPL thickness, and…
Get better, more continuous data?
Avoid field inefficiencies?
Reduce access and safety concerns?
These problems were solved for aquifer testing a long time ago with the introduction of datalogging pressure transducers
No more manual gauging for slug/pump tests.
How can we get that same reliability and operational benefit for LNAPL baildown tests?

5. Resolving In-Well LNAPL Thickness
Three related data points:
Air-NAPL Interface
NAPL-Water Interface
Potentiometric Surface
We can reliably measure:
Potentiometric Surface
LNAPL density
One interface +
Potentiometric Surface
LNAPL Density
Second Interface
LNAPL Thickness
Measured
Calculated

6. Measurement Concept
Pressure-Sensitive Tape (eTape) measures Air-LNAPL Interface
Hang in well at a fixed depth
Electrical resistance of eTape changes with fluid pressure (LNAPL or water) on PTFE envelope
Transducer measures potentiometric surface
Programmable datalogger collects readings and saves to SD card
NAPL thickness and NAPL- water interface calculated using LNAPL density

7. Equipment Waterproof case with: Metal frame for down-well equipment
Electronic datalogger
Intrinsic safety barriers
Wireless router
Internal or external 12V battery
Metal frame for down-well equipment

8. Field Trial
Baildown testing program in June 2015 – 8 wells Some key wells in high- traffic/difficult to access areas
Wells with large initial thickness, slow recovery
Built three automated data collection units

9. Results

10. Results

11. Well 1

12. If we were able to continue the test for 5+ days, we might see these small scale fluctuations, but would lack context
Well 1
With conventional methods, we would have gotten these data…
And a few points on days 2 and 3 – then stopped

13. Mobile LNAPL Interval (t2 ≤ t ≤ t3)
Better Data
Dense data points can help confirm confined LNAPL conditions (verifying CSM)
LNAPL Discharge
LNAPL Drawdown (sn)
Filter Pack Discharge
(t0 ≤ t ≤ t1)
Constant Discharge
(t1 ≤ t ≤ t2)
Mobile LNAPL Interval (t2 ≤ t ≤ t3)

14. Well 2
Some noise in this data set – we think likely due to passing trains and changing loads on soil
This data set has the same benefits as the other location – higher density, ability to better understand fluctuations… but there’s one big difference (as seen on next slide)

15. Well 2
Field staff can be here for an hour setting up, and then let the equipment run… rather than walking back repeatedly to gauge the well.
The location here is very difficult to access regularly and presents a lot of safety risks; using the ABDT can dramatically reduce the amount of time staff have to be here and the number of times they have to cross in and out of the location.
Continuous data for 5 days at a high- traffic/high risk location
Reduce logistical challenges and improve safety without losing data
Check on and download data wirelessly from a safer location

16. Continuous Improvement in LNAPL Management
Better Data
Cheaper Data
Safer Data
Summary & Questions
High-density data sets
More confidence in results
More efficient field time
Safer work in high-risk areas
Arcadis is pursuing a US patent and more field trials