Techniques for Developing High

Resolution Light Non-Aqueous Phase

Liquid (LNAPL) Conceptual Site Models

Roger Lamb, R.G – Roger Lamb Consulting

Presented by:

High Resolution LCSM Investigation Tools

• MIHPT – Detects VOCs in Fresh Gasoline, Jet Fuel,

Weathered Gasoline, EDB, MtBE and provides Qualitative

Permeability and Hydraulic Conductivity Estimates.

• uVOST/LIF – Detects LNAPL containing PAHs in ppm

concentrations – 10 to 500 ppm.

• Optical Imaging Profiler (OIP)– Detects LNAPL containing

PAHs and photos of the subsurface soils.

• Collaborative soil, groundwater, soil vapor analytical results

and lithologic data sets – Field Analysis Preferred.

MIHPT Diagram

3

Depth Detector

MiHpt Transfer

Line

Drill Rods

Electrical Generator

(self sufficient)

Ultra Pure Compressed Gases

4

Collaborative Data Set General Recommendations

Soil Samples – Cohesive Deposits

• Collect from target depths/locations based on direct sensing tool results- low, medium, high detector response - minimum 30 samples.

• Collect soil cores using closed-tubed sampling tools, maximum core length of 1 foot.

• Use Encore samplers or similar to collect soil samples from the soil cores.

• Document soil lithology and depth interval from which Encore samples are collected.

• Include in soil analysis TPH-GRO or DRO or similar depending on State requirements - Field Analysis Preferred.

Ground Water/ Soil Vapor Samples

• Install piezometers/wells/etc. based on based on direct sensing tool results- low, medium, high detector response.

• Use short screens, maximum length 5 feet for groundwater, 1 foot for soil vapor.

Questions

How many feet/day of

production will you

commonly achieve with

these tools?

Do you find the EC helpful?

Economic Benefits

Reduction in investigation costs

Increase in investigation data set

Increase in speed of decisions

Collected over 15 years Collected over 4 days

Total 2,255 Total 13,545

Conventional Tools High Resolution Tools

Average Site

Conventional Tools

Collected over 16 years

Total 3,568

High Resolution Tools

Collected over 10 days

Total 27,818

Large Site

Questions

How much would a similar

high resolution

investigation cost for a

refinery size project?

Technical Benefits

Hydrogeologic Characterization

LNAPL Body Distribution

Remediation Feasibility/Design

Hydrogeologic Characterization

Risk Assessment

Remediation Feasibility/Monetization

Remediation Pilot Testing, Design, Implementation

Soil Electrical Conductivity-Alluvial Deposits

Clays Clays

Topsoil

UST Pit

Sand Layers

Soil Electrical Conductivity-Alluvial Deposits

UST Pit

Alluvial Clays

Alluvial Sands

Hydraulic Profiling Tool- Alluvial Deposits

Permeability decreasing with depth

Hydraulic Profiling Tool- Limestone Residuum

highly variable permeability

Hydraulic Profiling Tool- Saprolite

High Resolution Hydraulic Conductivity Estimates

High K Zones

LNAPL Body Distribution

Source Determination

Risk Assessment

Remediation Feasibility/Monetization

Remediation Pilot Testing, Design, Implementation

Benzene in Ground Water

Former UST PIT

Ground Water Surface

LNAPL Migration in Sand Layers

X-section MIP PID Data Set

Mobile Phase LNAPL in Monitoring Wells

X-section uVOST Data Set

Isopach Map - uVOST Data Set

Total BTEX in Ground Water

Plan-view MIP FID Data

X-section MIP FID Data

X-section MIP FID Data

Questions

Do state agencies

commonly consider these

techniques as reimbursable

when performed at leaking

UST sites?

Are the hydrogeologic cross

sections shown in the

slides a product provided by

the tool vendors? or done

by the consultant?

Are there limitations of

using MIP in high

concentration soils or

potential NAPL areas?

What type of field QA/QC is

involved in these tools?

Some Lessons Learned

Monitoring wells do not need to be screened across the groundwater surface to detect mobile phase LNAPL.

LNAPL migrates to depths tens of feet below the groundwater surface.

LNAPL releases of different physical properties do not mix in the subsurface environment.

MIP PID/FID sensors indicate gasoline LNAPL at 30 feet

Monitoring well screened 27 to 32 feet contains mobile LNAPL

Monitoring well screened 15 to 25 feet does not contain LNAPL

Groundwater surface at 14 feet

MOBILE Phase LNAPL

X-section MIP FID Data

Questions

Is there such a thing as a

LNAPL smear-zone?

Develop Initial LNAPL CSM

• Establish Desired Results with Stakeholders.

• Fuel Types and Age of Releases – Weathered Gasoline, Fresh Gasoline, Diesel, Waste Oil.

• Hydrogeologic Data – Glacial/Alluvium/Cherty Clays.

• Map Mobile LNAPL – LNAPL that accumulates in wells.

• Map Soil and Groundwater Analytical Results – Above 1ppm Benzene which is indicative of LNAPL.

• Establish what results actually be achieved based on the initial LCSM.

Initial LCSM Considerations

Fold into the LCSM current understandings of:

• Residual/Mobile/Migrating LNAPL

• LNAPL Transmissivity

• LNAPL Biodegradation

• Vapor Intrusion

• Environmental/Remediation Hydrogeology

Questions

How much does it usually

cost to develop an LNAPL

CSM?

LCSM Field Investigation Design

Critical Field Design Considerations

1. Geologic Condition Issues- Cherty Soils or Shallow Bedrock.

2. Concrete Pavement – Have Coring Tools Onsite.

3. Weathered Gasoline – MIHPT system only

4. Leaded Gasoline – An MIHPT with and ECD Detector.

5. Inside Building or Tight Locations – Determine if accessible by contractors equipment.

6. Offsite Access - Plan for it based on initial LCSM.

7. Potential Impact of Offsite Chemical Releases.

Start with Anchor Points - Advance Direct Sensing Tools next to 3 to 6 sample locations that having the one of the following characteristics:

1. Has Contained LNAPL.

2. Groundwater Results over 1 mg/L Benzene or Naphthalene.

3. Soil Results over 1 mg/kg Benzene or Naphthalene.

4. Is of Interest Based on Potential Receptors or Other Factors.

5. Naphthalene concentrations at ppm concentrations in soil or groundwater samples is a positive indication that the uVOST/LIF or new OIP tool will detect the LNAPL.

Proposed LIF or

MiHPT soundings

locations

LNAPL In

Well

uVOST/MIP determination

soundings

LNAPL delineation

soundings

Questions

How common is it for the

uVOST not to detect

weathered gasoline LNAPL?

Implement LCSM Field Investigation

1. As high resolution data is collected, update the LCSM in real-time with focus on the project goals and determining what result(s) can be guaranteed.

2. Quickly determine if the uVOST/LIF is detecting the LNAPL.

3. Ensure all project stakeholders are updated to changes in the LCSM in real-time if possible and at a minimum daily. The whole technical project team must be updated in real-time.

4. Look for indicators of chlorinated solvents in the MIP sensor data either the ECD or XSD.

5. Fold into the real-time analysis modern LNAPL science and hydrogeology.

Mobile Phase LNAPL measured in monitoring well or bailer

Residual Phase LNAPL -Benzene Conc.

Completed MiHPT sounding with ID number as of 12/7

Figure 1 – Completed MiHPT as of 12/7

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5

6

7

8

9

3

10 11

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13 14

15

16

17

A

A’ B

B’ C

C’

Daily MIHPT Log Analysis Using DI Viewer Software

A A’

LNAPL Impact assumed if PID sensor values are over 1,000,000 uV.

Screen Shot of Smart-Data Solutions Website

Questions

How much does

SmartData Solution cost?

How can I contact this

firm?

Crunch Data Set Focused on Project Goals

• Project Business Goals – Redevelop a property impacted by an historical gasoline release.

• Technical Goals - Define extent of gasoline release above 2 mg/kg benzene action levels to aid in excavation design.

• Site Conditions – Historical gasoline release into residuum derived from cherty limestone.

• Investigation Design/Cost – uVOST and MIHPT - investigation depth 25 feet, 5 days of work, total direct sensing cost – $25,000.

• Investigation Results – uVOST failed to detect weathered gasoline LNAPL, MIHPT delineated onsite extent of weathered gasoline LNAPL and hydrogeologic conditions.

Case 1 – Excavation Feasibility/Monetization

MIHPT sounding locations in area of proposed soil excavation

Spatial analysis of MIP PID sensor readings

Residual soils decreasing in permeability with depth

MIP PID sensor readings in excess of

1,000,000 uV indicative of LNAPL impact

Collaborative Soil Sample Locations

Estimated volume of soil containing benzene in excess of the 2mg/kg action level – 460 cubic yards.

Project Business Goals – Determine why remediation system had not met project goals after 6 years and $700,000.

Technical Goals - Define extent of LNAPL and determine if remediation wells properly screened.

Site Conditions – Historical diesel, gasoline and kerosene releases into alluvial deposits.

Investigation Design/Cost – uVOST and MIHPT - investigation depth 20 feet, 4 days of work, total direct sensing cost – $20,000.

Investigation Results – uVOST detected diesel/kerosene LNAPL, MIP detected weathered gasoline LNAPL, HPT defined hydrogeology.

Case 2 – Remediation System Optimization/Monetization

Extent of Mobile Phase LNAPL

measured in monitoring wells

Extent of Diesel and Kerosene LNAPL based on uVOST

Extent of Mobile Phase LNAPL measured by monitoring wells

Extent of Weathered Gasoline LNAPL Based on MIP PID

Extent of Mobile Phase LNAPL measured by monitoring wells

Extent of Weathered Gasoline LNAPL Based on MIP PID

Extent of Diesel and Kerosene LNAPL based uVOST

Project Business Goals – Guarantee plume of gasoline impacted ground water stops migrating offsite.

Technical Goals - Define extent of residual phase gasoline LNAPL, define Hydrogeologic conditions and develop mass flux estimates.

Site Conditions – Historical gasoline releases into saprolite.

Investigation Design/Cost –MIHPT primarily with some uVOST - investigation depth 40 feet, 10 days of work, total direct sensing cost – $50,000.

Investigation Results – MIHPT define residual phase gasoline LNAPL and hydrogeologic conditions allowing for mass flux estimates, uVOST failed to detect weathered gasoline LNAPL. MIP ECD also detected EDB in LNAPL.

Case 3 – Remediation System Design/Monetization

Ethylene

Dibromide in

LNAPL

Sample locations used in Mass Flux Calculation

HPT Injection pressure through mass flux assessment area

High Resolution Hydraulic Conductivity Estimates

High K Zones

Calculated Mass Flux – 18 lbs/day gasoline VOCs

Wrap Up

Thank You

rogerlambconsulting@gmail.com

https://www.linkedin.com/in/rogerlambconsulting