Presented by: Thomas Hatton

Transcription

1 Presented by: Thomas Hatton 1

2 What is Vapor Intrusion? Methods of Correction Building Investigation Designing Effective Systems VI Mitigation in Existing Buildings VI Mitigation in Construction of New Buildings Operations, Monitoring, and Maintenance 2

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4 Potential Vapor Intrusion Contaminants : Volatile organic compounds (VOCs) Semi-volatile organic compounds Inorganics (i.e. mercury, hydrogen sulfide, etc.) Methane Radon Naturally-occurring / man-made contaminants Vapor Intrusion risks occur when you have: A source An inhabited building A pathway from the source to the inhabitants 4

5 Sub Slab Ventilation Systems Active Soil Depressurization Systems (ASDS) Existing Buildings Passive Soil Ventilation Systems(PSVS) Accelerate Attenuation New Construction Preemptive mitigation Aerated Floor Systems Soil Vapor Extraction 5

6 Create negative pressure below the slab Designed to function under max load conditions Achieve state mandated vacuum requirements Continual operation and monitoring 6

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8 Mix of stakeholders often with competing interests Property owners Tenants Responsible party Bank Attorneys Know the project participants, their function and chain of command Free flow of information between all parties Get an access agreement

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10 Sampling and design Critical project component Have an honest and open discussion with client Sets course of action Eliminates surprises later on Determines quality of outcome 10

11 1. Building Investigation 1. Contaminate Plume Delineation 2. Evaluate Building Pressures 3. Pressure Field Extension Testing 2. Design 3. Installation 4. Start Up and Balance 5. OM&M 11

12 Ask for as much information as possible Understand the building s history Ask for the entire history of blueprints Learn as much about additions as possible There will be a combination of active and abandoned utility lines Ask for an under slab utility mark out If possible find a maintenance person to interview

13 When was the building built? Have any additions been added to the building? Do you have As Built construction drawings? What are the different foundation constructions? What type of soil is around and under the building? How thick are the slabs? What utilities are under the slab? Are there machine pads? What is the roof construction? Who holds the construction warranties? Is there a high water table problem?

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15 How is the building heated and cooled? Has the HVAC system been modified over the years? How is the HVAC controlled and what cycle is it on? Who provides HVAC maintenance and repair? How is outdoor air brought into the building? Does the floor plan include the location of any building exhaust fans?

16 Dampened Passive Exhaust Powered Exhaust 16

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18 Check for interior bearing walls and grade beams Check foundation cross sections for sub-slab material Determine if sub-slab material is specified Locate any sub-slab utility runs or tunnels Find any slab elevation changes

19 Present a good case for sampling budget What are the contaminants What are the concentrations In the groundwater In the soil In the indoor air In the ambient air Is methane present

20 using a mobile lab 20

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24 Commercial buildings typically have an expansion material between slabs, floor wall joints and multiple slab penetrations.

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26 Understanding Vapor Intrusion pathways Building pressures Soil permeability Vacuum required for depressurization Soil airflow yields 26

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29 Based on: Contaminants / Concentrations Building layout Construction features Existing utilities HVAC Sub slab Exhaust blowers Soil permeability 29

30 Vacuum (''w.c.) Regenerative 40 GBR HO 40 (Brushless Radial) 30 Cincinnati HP-8D19 (Radial) 20 GBR SOE 16 (Brushless Radial) 10 AMG Force (Centrifugal) GBR 89-HA (Brushless Radial) Airflow (cfm) 30

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34 Vapor Barrier Vapor Retarder Thickness >10 mil. <6 mil. Permeance < 0.1 perms > 0.1 perms 34

35 North Jersey School Standard Vapor Barrier and Vent System vs. Georgia School Liquid Boot and Vent System 38,000 ft 2 3 Story 24,000 ft 2 3 Story 35

36 North NJ Georgia Approx. Square Feet 38,000 24,000 Riser per Sq Ft One 4 per 2,700 One 6 per 24,000 Average Vacuum Sub Slab Blowers Estimated Annual Blower Cost * Est. Leakage per 10,000 Sq Ft Fourteen 118 watt blowers One 125 watt blower $457 $ CFM 49.5 CFM *cost per 10,000 ft 2 at $0.14 per KWH 36

37 North NJ Georgia Savings Electric* $457 $63 $394 Heating: ** $ 672 $77 $595 Cooling: * $96 $11 $85 Total Savings $1,074 * Electric Cost at $0.14 per KWH ** Natural Gas Cost at $12.50 per 1,000 cubic feet 37

38 1 pallet of aerated floor material = 35 yards 3 of fill Saves up to: 20% on reinforcement steel 40% on concrete Enables passive venting Costs less than active Easy installation 38

39 Pipe Slopes Discharge Requirements Permanent Sampling Ports Designing for Location Using Building Characteristics to your advantage 39

40 Ensure service factor of blower is not exceeded 40

41 Adjust gate valves and measure riser data 41

42 Quarterly Inspections Visual Inspections System Performance Metrics Annual Quarterly and Sub Slab Vacuum Field Confirmation Riser Vacuum, Airflow and Vapor Determine contaminate reductions Gate valve balancing 42

43 Long Term Monitoring Reporting Extended Stewardship Exit Strategy Termination Deed Restrictions 43

44 More on Remote Monitoring tomorrow morning 44

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