Integrated Vapor Intrusion Mitigation and Soil Vapor

Extraction Implementation for a Complex Building

Foundation

Authors: Omer J. Uppal, Matthew Ambrusch, Steven Ciambruschini,

Nadira Najib, Stewart H. Abrams, and Matthew Wenrick

Presentation Outline

Vapor Intrusion

How to Mitigate

What is SSDS?

SSDS Versus SVE

Components of a SSDS Design

SSDS Design Challenges

Case Study – Manhattan, New York

Lessons To Be Learned

Vapor Intrusion Migration of volatile chemicals from contaminated groundwater or

soil into buildings above

Indoor Air Quality

Chronic and acute health/safety hazards

How to Mitigate

Passive Venting Systems

Impermeable Membrane Liners

Sub-Slab Depressurization Systems

http://www.nj.gov/dep/srp/guidance/vaporintrusion/subsurface.htm

What is a SSDS?

Active venting system consisting of:

Fan/Blower

Well Network

Vacuum/Air Flow Rate Instrumentation

Control Panel

Telemetry System

Emission Controls

SSDS Versus SVE

Differences: Purpose

MITIGATION versus REMEDIATION

Capture versus Extraction

Similarities: Principals

Active Pneumatic Systems

Dependent on intrinsic permeability

Design Components of a SSDS Design

• Pilot Testing

• Modeling

• Design Criteria

• Air Flow Rate

• Vacuum

• ROI

SSDS Design Challenges

• Existing Structures

• Slab on grade

• Space/Access Constraints

• Heterogeneous Geology

• High Water Table

Case Study – Manhattan, New York

Site Background

Operated until June 2013 as an active dry cleaning facility

Residential dwellings located on floors two through five.

Indoor air assessment - PCE and TCE in exceedance of NYSDOH

Vapor Intrusion Guidance Matrix.

Site Constraints

2 - 6 inch thick concrete slab with granite bedrock beneath

Limited space for implementation/Manual drilling required

Possible demolition of building during application period

Pilot Testing

5 Vapor Recovery Wells (VP)

3 Shallow Vapor Probes (SVP)

Understand the site-specific sub-surface parameters (i.e., permeability)

to design the full-scale SSDS.

Outputs:

Ki, ROI, FD , PV exchanges

Benefits:

More cost-effective design

Valuable tool for SVE and VI Mitigation systems

Helps to ensure efficient and effective vapor mitigation

Modeling

MDFIT – Computer Pneumatic Modeling Program

Full-Scale Results

SSDS was meeting the required minimum sub-slab vacuum of

0.004 inches of water column (as recommended by USEPA)

Mitigating AND Remediating

Lessons To Be Learned

SSDS can be performed efficiently, even at complex sites, if we

understand and consider the constraints of the site when designing

the system.

Importance of pilot testing and pneumatic modeling when

designing/installing a SSDS in an existing building.

Properly designed systems can provide effective mitigation even in

a complex lithology (i.e., bedrock).

Questions?