passive soil gas surveys using gore-sorber® modules

Passive Soil Gas Surveys Using GORE-SORBER® Modules

Bob Jurgens, Kansas Drycleaning Program

Kansas Department of Health and Environment

What is a GORE-SORBER® Module?

� Patented soil gas sampler

� W.L. Gore & Associates � Makers of GORE-TEX material

� Outdoor clothing

� Floss

� Module contains polymeric & carbonaceous adsorbents

� Expanded polytetrafluoroethylene � Chemically & biologically

inert

� Waterproof

� Vapor permeable

� Strong & durable

ePTFE - 50,000 x

GORE-SORBER® Module

magnification

GORE-SORBER® Module

How it works

Insertion/retrieval cord

Adsorbent

Water & soil

particles repelled

Vapors pass through

membrane

Create installation hole

Place insertion rod in module

Insert module into hole

Secure module, mark field location, record map information and field notes

Module installation 1 2

3 4

Installation Tools

Hammer & Probe

Slide Hammer& Tile Probe

Rotary Hammer Drill & Carbide Tipped-Drill Bit

Geoprobe

Installation Lessons Learned

� KDHE uses a direct push probe to install modules in outdoor hard surface lots.

� KDHE installs to a depth of 4 feet bgs and leaves a minimum of two weeks.

� Explain the project to the property owner. They will often watch out for the locations and help prevent vandalism.

� Bury beneath the ground surface to avoid problems with lawn mowers and snow removal equipment.

Installation Lessons Learned

� Hide/cover the locations to prevent vandalism (removal of the modules).

� Place a metal washer above the cork plug to allow use of metal detector to locate the hole

� Measure exact locations from secure structures

� Flags and paint will disappear

� Beware of surface water or hydrated bentonite during the winter (frozen media) � Will need to chip out the material in the hole

Indoor Locations

Retrieval Process 1 2

3 4

Hole Cover

Cork Plug

Place module in jar

Shipping Jar

Completing the Job

Outdoor Installation

Installation Hole

Cork Plug

Sample Analysis

� Thermal desorption/gas chromatography/ � mass spectroscopy (TD/GC/MS) � Modified EPA method 8260/8270

� Accepted for CERCLA/RCRA investigations � Compound specific reporting

� Rigorous QA/QC Program � Accurate, reproducible results

� Analytical options include � Target and non-target compounds � TICs, TPH, GRPH, DRPH

Final Reporting GORE-SORBER® SURVEYS � Pre- and post-survey consultation

� Survey design and data interpretation

� Bound final report includes � Chain of Custody � QA/QC summary � Data tables, TICs � Color contour maps � Survey comments

� Available electronically

Quick & Easy Wash-O-Mat PCE Soil Gas Survey Map

Quick & Easy Wash-O-Mat TCE Soil Gas Survey Map

Quick & Easy Wash-O-Mat cis-1,2 DCE Soil Gas Survey Map

Comparing the Maps PCE

TCE

Cis-1,2 DCE

Cost

� KDHE Cost – 1999 � GORE-SORBERS: $181.50/each*

� KDHE Cost – March 2002 � GORE-SORBERS: $258.50/each*

� Neodesha Project: $10,300 � Detailed investigation

� 27 GORE-SORBERS

� Geoprobe Installation

* = includes 10% subcontractor markup

GORE-SORBER® SURVEYS Advantages

� All soils - low to high permeability � All soil moisture conditions - dry to

saturated settings � Waterproof, vapor-permeable membrane

� Relative correlation to matrix data � Elevated soil gas levels = elevated levels in

subsurface

� Concentrations are not a “snapshot” � Collected over a longer period of time

GORE-SORBER® SURVEYS Advantages Cont.

� Relatively unobtrusive, quick installation & retrieval - field technician � Indoor or outdoor � Install – KDHE projects 20-30 in one day � Retrieval - KDHE projects 20-30 in 1/2 day

� Replicate samples per collector � Duplicate analysis - QA/QC � Back-up analysis

installation

GORE-SORBER® SURVEYS Disadvantages � Two trips to the field

� Lengthier sampling and reporting period

� Data reported as mass (ug) not a concentration

� Compound detection in vapor limited due to volatility and Henry’s Law

� True for all soil gas sampling

� Vandals can pull out modules if not hidden properly

Why does KDHE use this technology?

� Helps identify “hot spots”

� Works very good for PCE

� Active soil gas sampling was not providing dependable results

� Soil sampling – easy to miss contaminated area

Contacts

� KDHE – Bob Jurgens, Project Manager � Phone 785-291-3250

� W.L. Gore & Associates � George Shaw – 410-506-4776 *

*As a state agency, KDHE does not endorse specific companies. information only.

This information is provided for contact

Questions or Comments?