New Groundwater Techniques and Technologies 17 th Annual RETS REMP Conference June 25-27, 2007 Eric L. Darois, CHP EPRI Consultant/RSCS Inc.
Dec 14, 2015
New Groundwater Techniques and Technologies
17th Annual RETS REMP Conference
June 25-27, 2007
Eric L. Darois, CHP
EPRI Consultant/RSCS Inc.
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Project Scope
• Evaluate New and Current Technologies for Groundwater Sampling
• Evaluate New and Current Technologies for Contaminated Groundwater Detection
• Evaluate New and Current Technologies for Contaminated Groundwater Remediation
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Technology Conferences
• 7th Passive Sampling Workshop and Symposium, Reston Virginia, United States Geological Survey (USGS), April 2007
• 2007 Ground Water Summit, Albuquerque New Mexico, National Ground Water Association (NGWA), April 2007
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Passive Sampling Technologies
• SPMD’s– Semi-Permeable Membrane Devices (SPMD’s) – These accumulate contaminants within an absorption media, typically a polyethylene absorption
media.• The Gore Module
– Developed exclusively produced by and for GORE-TEX® – Similar to SPMD’s, does not collect a sample of water, uses a patented absorption
material. – Consists of a tube of GORE-TEX® fiber containing absorption beads. – Has pore sizes large enough to allow volatile and semi-volatile gas phase contaminants
to diffuse and to accumulate on the absorption material.– Pore size restricts liquid phase water from entering the sampler.
• PDBS– Passive Diffusion Bag Samplers (low-density polyethylene diffusion bag samplers)– Collects groundwater samples using a tube of Low Density Polyethylene (LDPE). – Fits into a 5 cm dia. well. – Filled with DI Water, sealed at both ends and lowered into Well.– Averages Concentration over 1 – 2 weeks – no additional equipment
• RCDMS– The Regenerated Cellulose Dialysis Membrane Sampler (RCDMS) – Similar to the PDBS. – Pore size between 5-20 microns.– May Be Susceptible to Degradation
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Passive Sampling Technologies (con’t)
• RPP– The Rigid Porous Polyethylene sampler (RPP)– Also Similar to PDBS and RCDMS– Porous polyethylene membrane with pore sizes ranging between
6 and 15 microns. – Limited to 100mL sample
• The Snap Sampler– Groundwater passive grab sampler. – Device consists of a sample bottle, trigger lines, end caps and springs– Sample Volumes of 40 and 125 mL.
• The Hydra Sleeve– Groundwater passive grab sampler. – Disposable thin-wall sleeve of polyethylene sealed on the bottom and
fitted with a one way reed valve on the top. – Effectively Collects a Core of Water ~1000 mL
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Passive Sampling Comparisons
Diffusion Sampler
Grab Sampler
Commercially Available
DisposableLimited by
Sample Volume
Easy to Use
Snap Sampler X X X
RCDMS X X
RPP X X X X X
Hydra Sleeve X X X X
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Tritium Groundwater Contamination DetectionSoil Vapor Extraction System (SVES)
• Current EPRI Research Initiative
• 4 Project Phases
– 1 Develop Predictive Model
– 2 Laboratory Testing of Model
– 3 System Test at a Decommissioning Site with Characterized H-3 Plume
– 4 System Test at Operating NPP
• Currently Beginning Phase 2
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SVES Basis
• Research Currently at the Armagosa Desert Research Site
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SVES Principle
• Extract Soil Vapor from Vadose Zone
• Condense Vapor, Analyze for H-3
• The Vadose Zone H-3 Vapor “Plume” Likely Extends Well Beyond Contaminated Groundwater
• If the H-3 Vapor is Within the Extraction Zone of Influence, Detection will Occur.
• System May Provide Early Indication of H-3 Subsurface Leak.
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Project Objectives
• Determine Physical System Configuration Requirements
• Determined Required Data for System Installation
• Evaluate Sensitivity of SVES to “detect” Groundwater Contamination
• Provide for Data Assessment Methodologies
• Prediction of:
– Soil Gas Velocity
– Radius of Influence
– Subsurface Release Activity
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SVES Model
• Principal Parameters
– Soil Gas Velocity,
– Air Permeability, and
– Pressure Gradient.
Pkaq
q discharge velocity (discharge) [m/s]
ak air permeability [m2] viscosity of air [kg/m/s]
P instantaneous pressure gradient [(kg/m/s2 )/m]
iraa kkk gP
kk
w
wsi
ks= saturated hydraulic conductivity [m/s] µw= viscosity of water [kg/m/s] Pw= density of water [m3 /kg] g= acceleration due to gravity [m/s2]
Figure 1.1Typical Relationship Between Vacuum vs Radius from
the Extraction Point
Radius
Vacuum
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Model Assumptions
• The thickness of the vadose zone is relatively constant, homogeneous and isotropic within the extraction point’s ROI, i.e. construction backfill.
• An impervious or semi-pervious surface barrier to atmospheric gas transfer and direct infiltration of precipitation to the vadose zone is in place, i.e. pavement or concrete.
• A detection or change in condensate activity concentration is due to a soil vapor plume entering the ROI of an extraction point and is not the result of diffuse background H-3 activity in the soil.
• The approximate cross-sectional area OR volume of contaminated soil AND the approximate distance from the extraction point can be determined.
• Soil vapor within the capillary fringe of the liquid plume has the same activity concentration as the liquid release.
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Conceptual Design
• Each Extraction Capable of Covering Large Areas
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Specific Discharge and Capture Ratio
• Specific Discharge Within Plume Front
• Total Discharge at Plume Front, Qr
• Geometric Capture Ratio,
rpf qccbbQ )'()'(b-b’= plume width [m] c-c’= plume depth [m] qr= soil gas velocity at the plume front radius [m/s];
r
pf
Q
QC
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Ideal and Non-Ideal Conditions
• System is More Effective with Concrete or Asphalt Cover
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Cylinder-Sphere Model – Non-Ideal
2
4)2(
2
4
2
))(()(2
22 rcr
r
r
rrrTrA t
os
osos
Total Surface Area
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Additional Model Considerations
• Thick Vadose Zone
• 3-D Rendering to Determine Shape Surface Areas
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SVES Benefits
• Fewer GW Monitoring Wells
• More Effective Sentry System
• Onsite Analysis for H-3
• More Effective Early Warning Methodology
• Less Dependent on Precise Placement
• Less Invasive (Push-Probe Installation Method) than Traditional GW Monitoring Well
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Project Schedule
• Phase 1 – Complete
• Phase 2 – 12/31/2007
• Phase 3 & 4 – 12/31/2008