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ACTIVITY NAME
Vapor Intrusion MitigationFormer Naval Air Station Moffett Field
Restoration Advisory Board Meeting May 11, 2017
Wilson DoctorNavy Project Manager
5 BRAC Program Management Office.
Vapor Intrusion MitigationSchematic of Vapor Intrusion Pathway
6 BRAC Program Management Office.
Vapor Intrusion Mitigation Methods
Vapor Intrusion Mitigation Methods
– Eliminate preferential pathways
– Increase ventilation inside the building
– Active sub-slab ventilation (depressurization)
7 BRAC Program Management Office.
Vapor Intrusion Mitigation Methods
Eliminate Preferential Pathways– Fill subsurface vaults – Seal cracks/expansion joints in floor slabs– Seal pipe penetrations/floor drains
Sealing floor cracks Sealing floor drains
8 BRAC Program Management Office.
Vapor Intrusion Mitigation Methods
Increase Ventilation Inside the Building– Fresh air intake – Increased air exchange rate
9 BRAC Program Management Office.
Vapor Intrusion Mitigation Methods
Active Sub-slab Ventilation– Sub-slab depressurization system creates a negative pressure field below the building preventing soil gas from entering the building
Schematic Sub-Slab Depressurization System Sub-Slab Depressurization Blower and Vent
10 BRAC Program Management Office.
Confirmation Sampling
ROD Amendment for the Vapor Intrusion Pathway (EPA, 2010) for long-term exposure
Chemical of ConcernIndoor Air Cleanup
Level (µg/m3)
Commercial
Trichloroethene (TCE) 5
Perchloroethylene (PCE) 2
cis-1,2-Dichloroethene 210
trans-1,2-Dichloroethene 210
Vinyl Chloride 2
1,1-Dichloroethane 6
1,1-Dichloroethene 700
Following implementation of mitigation measures, conduct air sampling to verify effectiveness.
11 BRAC Program Management Office.
Current Status and Schedule
• Vapor Intrusion Mitigation Work Plan– Draft submitted March 17, 2017– Final scheduled for Summer 2017
• Vapor Intrusion Mitigation Field Work– Scheduled for Fall 2017 through Spring 2018
• Completion Report– Draft scheduled for Summer 2018– Final Scheduled for Winter 2018
12 BRAC Program Management Office.
Vapor Intrusion Mitigation
QUESTIONS ?
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