Brownfields_Content Page_Vapor Intrusion Resources For Environmental Professionals

Vapor Intrusion Resources For Environmental Professionals

Screening for vapor intrusion (VI) must be conducted at every contaminated site in Wisconsin (Wis. Admin. Code § 716.11(5)(g)). When screening indicates the potential for vapor intrusion, the need to investigate increases, especially when trichloroethylene (TCE) is present because of its potential to cause health risks. Exposure from vapor intrusion can be mitigated so the vapors no longer pose a risk. Mitigation is not a form of remediation.

This webpage includes resources for environmental consultants to screen for vapor intrusion, assess vapor risk and investigate and mitigate vapor intrusion when necessary.

The Responsible Neighbor, a Vapor Intrusion Story – this video shows how good communication with neighboring property owners affected by environmental contamination benefits everyone involved with an environmental cleanup.
 

Guidance & Resources

DNR Resources

Wisconsin Department of Health (DHS) Resources

ITRC & AVIP

U.S. EPA Resources

Forms

The DNR's web-based forms allow users to enter information and upload related photographs online. Information is automatically saved and changes can be made before the form is submitted to the DNR. New users must create an email log-in to access DNR's web-based forms.  

Vapor Mitigation System Inspection Log (Form 4400-321) - Use this form to conduct and document annual inspections of vapor mitigation systems for submittal to the DNR. Email DNRRRVAPOR@wisconsin.gov with issues related to Form 4400-321.

Vapor Intrusion Building Evaluation (Form 4400-011) - Assists with completing building-specific vapor investigations and mitigation documentation. Submit through the DNR's RR Submittal Portal as supporting information.

DNR filled out sample forms for training purposes. DNR entered minimum information in required fields and where needed to reveal secondary prompts. Reference the sample forms to prepare for a vapor mitigation system inspection or building evaluation. Do not use the sample forms for submittal purposes.

Screening Levels

Vapor Quick Lookup Tables of Indoor Air Vapor Action Levels (VALs), Vapor Risk Screening Levels (VRSLS) And Attenuation Factors

The Wisconsin Vapor Quick Look-Up Table Indoor Air VALs and VRSLs (RR-0136) - provide a set of summary tables for indoor air vapor action levels (VALs) and sub-slab, soil gas and groundwater vapor risk screening levels (VRSLs) for chemicals commonly found in Wisconsin and instructions for determining or calculating VALs or VRSLs for additional contaminants. The values are based on U.S. Environmental Protection Agency (U.S. EPA) Regional Screening Levels (RSLs). The publication includes:

  • Indoor air VALs for VOCs frequently encountered in residential and commercial/industrial settings
  • Sub-slab vapor risk screening levels (VRLs) for residential, small commercial and large commercial/industrial buildings
  • Attenuation factors for five screening media at three separation distances from a building foundation
  • Groundwater VRSLs for three building categories at three separation distances from a building foundation
  • Groundwater VRSLs for tetrachloroethylene (PCE) and trichloroethylene (TCE) at three separation distances from a building foundation
  • Instructions for determining VALs and sub-slab and groundwater VRSLs for other chemicals using the U.S. EPA's Vapor Intrusion Screening Level (VISL) Calculator
  • Formulas to convert units of data [e.g., parts per million by volume (ppbV) to µg/m3]

History of Changes To VALs, VRSLs and Attenuation Factors For Common VOCs

Changes to Wisconsin's VALs and VRSLs over time due to updates to U.S. EPA's risk calculations and default attenuation factors are available in the History of Changes to Vapor Quick Lookup Tables (RR-0137).

Using U.S. EPA's Vapor Intrusion Screening Level (VISL) Calculator To Determine Wisconsin VALs and VRSLs

The U.S. EPA Vapor Intrusion Screening Level Calculator (VISL) and VISL User Guide may be used to calculate VALs and VRSLs for compounds not listed in the Guidance: Vapor Quick Lookup Tables. To use the calculator:

  1. Adjust the default hazard quotient to 1
  2. Adjust the default target risk to 10-5
  3. Choose the exposure scenario (resident or commercial/industrial)
  4. Select one or more individual chemicals in the selection field

The calculator will provide the “target indoor air concentrations” for the carcinogenic and noncarcinogenic endpoints for the individual chemical(s) selected. The VAL is equal to the lesser of the two values rounded to two significant figures. The calculator will also provide the “target sub-slab and near source soil gas concentrations” for the individual chemical(s) selected using a default attenuation factor of 0.03 and the VAL.

More detailed instructions, including how to calculate VRSLs using a site-specific attenuation factor, are listed on the Guidance: Vapor Quick Lookup Tables (RR-0136).

Health Information

The DNR partners with the Wisconsin Department of Health Services (DHS) and local health departments regarding short-term (acute) and long-term (chronic) risks to human health related to vapor intrusion, as well as determining appropriate immediate and interim recommendations (e.g., ventilation, mitigation) at affected sites. DHS and local health departments assist the DNR, responsible parties and environmental consultants with health risk communication related to environmental contamination.

Sharing Demographics

When there is a known exceedance of the indoor air vapor action level (VAL) and/or sub-slab vapor risk screening level (VRSL), collecting information about the occupants of the building is important to determine the applicable health risk, a timeline for a response and the type of specific immediate or interim actions needed (Wis. Admin. Code §§ NR 708.05 and 708.11.)

When sharing occupant information or demographics with the DNR, focus on identifying any sensitive populations present (e.g. children, women who are or may become pregnant, elderly). Do not include personal information such as names, specific ages, personal addresses and individual occupancy habits (e.g., work hours).

DHS Resources Specific to Trichloroethylene (TCE)
DHS Letters to DNR Related to TCE

For more information about vapor intrusion and health, visit the following resources:

Community Outreach

An effective outreach strategy that anticipates the needs and concerns of affected property owners and the community at large is important when vapor intrusion is involved. When citizens are well-informed about the issues surrounding a site, their questions and concerns can be more effectively addressed. Early two-way communication is essential for a successful investigation and mitigation effort. The following model letters and fact sheets are available for use as you see fit, in whole or in part.

Introductory Information

Request For Access To Sample

Sample Results

Request To Install Mitigation System

DNR Fact Sheets

These fact sheets are available for use by environmental consultants and responsible parties to communicate critical information about vapor intrusion to affected property owners.

DNR Videos

The videos are intended for use in conjunction with fact sheets or other documents to help environmental consultants and responsible parties communicate critical information about vapor intrusion to affected property owners.

Active Notification & Telemetry

Continuous monitoring of a vapor mitigation system (VMS) is important to ensure that the system continues to work as designed. Active notification can provide notification using audible alarms, visual indicators and/or telemetry systems when the system is not working properly. Telemetry systems allow remote notifications of a VMS failure via an automated phone message, email or text to individuals who may be offsite and can measure additional parameters (including fan amperage, sub-slab/indoor air pressure differential, temperature and barometric pressure) at sampling intervals determined by the operator. A backup power system safeguards operations of an active VMS in the event of a loss of power.

Best Practices For Active Notification And Backup Power At Sites With Active VMS (Based On Health Risk And Land Use)

Type Of Health RiskLand UseAudible Alarm/
Visual Indicator		TelemetryBackup Power
ChronicAllRecommendedOptionalOptional
AcuteAll except multi-familyRecommendedOptionalOptional
Acute [including due to trichloroethylene (TCE)]Multi-familyRecommendedRecommendedRecommended

Note: Chronic health risks represent the potential for health impacts over longer exposure durations, and acute health risks represent potential health impacts over shorter exposure durations.

Telemetry Best Practices

  • Program each pressure gauge/transmitter for the telemetry system individually to provide alerts when operating parameters are outside the range of acceptable VMS performance
  • Set telemetry alert thresholds to capture a percent change in pressure from the established baseline measurement of a given fan/extraction point
  • Send alerts via telemetry within four hours of VMS system failure for set parameters or with a deviation of 20% change in the vacuum measured in the riser just below the fan
  • Notify the individual(s) responsible for the VMS within four hours of a system where TCE is a contaminate of concern, or within 24 hours for other contaminants
  • Develop an operation, monitoring and maintenance plan for the system that includes:
    • Schematic and photographs of system elements, including the location of all sensors and communication hubs
    • Parameters measured, including vacuum for each system fan and others, as applicable: sub-slab/indoor air pressure differential, fan amperage, barometric pressure, temperature, humidity and airflow
    • Parameter sampling frequency (i.e., how often the system reports the parameter to the responsible individual)
    • Parameter measurement sensitivity (e.g., inches water column (WC) for vacuum)
    • Notification trigger for each parameter (e.g. inches WC for vacuum) and rationale for the chosen values
    • Notification delay: the length of time after an alarm is triggered before a notification is sent through the telemetry system. The delay is intended to minimize false alarms yet provide notification quickly enough to minimize impacts to indoor air
    • Backup power protocol if the primary power fails (e.g., low battery alarms, battery backup and backup generator for the VMS)
    • System provider and specifications
    • Method of notification (e.g., email, phone message and text message) and individual(s) notified
    • Anticipated follow-up actions for each parameter

Contact the DNR project manager if you have questions regarding whether site-specific conditions may warrant continuous monitoring of the active VMS. For additional information regarding best practices from the Indoor Environments Association (formerly AARST), see ANSI/AARST Soil Gas Standards.

Training

The Remediation and Redevelopment Program provides web and teleconference-based training sessions that cover a variety of technical and policy issues. Visit the RR Program training library to find presentations on vapor intrusion-related topics.

Other Resources

CLU-IN Focus Website for Vapor Intrusion. Access webinars on VI sampling, data evaluation and mitigation.

Indoor Air Vapor Intrusion Database, RTI International. Access to presentations from past U.S. EPA-sponsored workshops and conferences focused on innovative and evolving ways to address vapor intrusion.

ANSI-AARST Standards. Provides design standards for soil gas mitigation of existing buildings and new construction.

Sewers and Utility Tunnels as Preferential Pathways for Volatile Organic Compound Migration into Buildings: Risk Factors and Investigation Protocol, Department of Defense Environmental Security Technology Certification Program (ESTCP).

Vapor Intrusion Mitigation in Construction of New Buildings Fact Sheet, Naval Facilities Engineering Command (NAVFAC).

Vapor Intrusion Mitigation in Existing Buildings, Naval Facilities Engineering Command (NAVFAC).

Passive Sampling for Vapor Intrusion Assessment, Naval Facilities Engineering Command (NAVFAC).

Contacts

For more information, contact DNR's vapor intrusion experts.

For more information, contact