2.1 Overview of AVMS
This section should include a design basis that explains how vapors are entering, or may enter, the structure and how the AVMS will prevent unacceptable soil vapor concentrations from entering the structure. It should include an overview of the type and functionality of the mitigation system proposed (e.g., sub-slab venting, sub-slab depressurization, etc.) and portions of the structure requiring mitigation.
2.2 Design testing
2.2.1 Overview
This section should include an overview of the diagnostic tools that will be used for proposed structures or were used for existing structures to develop the AVMS design. Information gaps identified should be discussed.
2.2.2 Pre-design sub-slab diagnostics: Pressure field extension (PFE testing)
This section should describe the PFE testing procedure and results including:
- An evaluation of pressure differential between the building and sub-slab prior to testing for an existing structure.
- An evaluation of the findings and how they relate to the proposed design (e.g., testing flow/vacuum correlated with design flow/vacuum)
- A discussion of known subsurface features (see Section 1.5, 1.6, and 1.7) and if/how they influenced the PFE testing.
- A discussion of any evidence of poor effectiveness (i.e., unexpected low vacuum. measurements at test ports associated with the tested exhaust vent pipe)
- A discussion of any inconsistencies identified (i.e., unexpected differences between vacuum at one test port compared to another test port that is associated with the same suction point).
- A discussion of any design consideration(s) for the AVMS based on the results
If the PFE will not be completed at the time of the submittal because a building will not be built, this section should describe and provide information about how the above items and analysis will be performed.
Key supporting information
- Figure(s) that identifies where the PFE tests were completed or are proposed.
- Figure(s) that depicts the PFE testing data, including maps showing the extraction point(s) and the influence of the system.
- Table(s) that summarizes the data collected.
2.2.3 Building HVAC testing and evaluation (required)
This section should include an evaluation and analysis of the proposed or installed HVAC system(s) and the potential pressure gradients generated by the AVMS. Testing should be conducted in accordance with recognized national standards or other similar procedures. This section should also include an analysis of the findings and the impact on the design. If any natural draft appliance(s) such as fireplaces or hot water heaters are present, or will be installed, include a description of the backdraft testing that has or will be performed during the installation process.
Alternate Definitive Statement that may be utilized: All building pressure and/or alterations to the pressures and venting will be analyzed and evaluated. Any natural drafting appliances will be backdraft tested in accordance with Section 11.5 of EPA 1993 or similar procedure and documentation will be made available as part of any installation and commissioning process.
Key supporting information
- Data as required to make the evaluation.
2.2.4 Other testing (if necessary)
This section should include any other diagnostic evaluation or testing that was, or will be, performed, including:
- Characterization of pressure or air exchange rates between indoors and outdoors
- Characterization of pressure or air exchange rates between floors or adjoining air spaces
- Diagnostic radon measurements or other contaminant measurements at locations of interest
The need to perform additional diagnostic testing is typically done when installers are trying to obtain additional information to design the AVMS or to obtain baseline information that, after a system is installed, will support that the AVMS is effective in mitigating an unacceptable risk.
Key supporting information
- Data required to make the evaluation.
- Figure(s) that identifies where the tests were completed.
- Table(s) that summarizes the data collected.
- All information should be included in a separate appendix.
2.3 Plan of proposed system
2.3.1 Suction pit and vent lines
This section should describe the suction pit construction or the mechanism(s) creating depressurization of the area beneath the building that is demonstrated as necessary to be mitigated.
Key supporting information
- Figure that depicts the suction pit or piping, and vent lines beneath the slab.
2.3.2 Horizontal conveyance piping (if installed or proposed)
This section should include a general description of the horizontal conveyance piping used to direct the vapors through the structure. In addition, any slopes in the piping that need to be maintained should be described including that pipes should be sloped back toward suction pits or points to allow potential condensation to drain out of the conveyance piping.
Key supporting information
- Figure that depicts horizontal conveyance piping layout of the AMS.
2.3.3 Vertical vent risers and height of building
This section should include a general description with any limitations that must be addressed when routing the vertical piping to and above the roof.
Key supporting information
- Figure(s) in plan view that depict the vertical piping run locations (may be identified on Figures for Section 2.3.3.)
- Cross-section(s) of structure that details the vertical piping runs.
2.3.4 Fans
This section should identify the fan-type that is to be used. In addition, general operational parameters of the fan, such as vacuum and air flow, should be provided and discussion of how it will match the design flow and vacuum is required. If a fan has not been selected, then this section should detail how the data will be used to select the fan(s).
2.3.5 Exhaust vents
This section should include a general description of the proposed location(s) of the AVMS exhaust point(s). This section should identify the distance that must be considered and met as measured from the AVMS exhaust point(s) location(s) including height above structure or roof, other air intake(s), window(s), structure access point(s) such as a door or patio, and HVAC components based on AARST SGM-SF-2017.
Note: All distances should be measured between the closest point of the exhaust opening and the closest point of all location requirements specified.
Key supporting information
- Figure(s) – plan view that depicts the piping roofing locations and any other vents or air intakes that influences the location of the exhaust.
- Figure(s) – cross-section of structure that details the exhaust vents height above the structure.
2.3.6 Materials and other specifications
2.3.6.1 Sealing cracks, joints, and other openings
This section should include the proposed sealing of cracks, joints, or other openings that is necessary to obtain and maintain the necessary pressure gradients generated by the AVMS. Alternatively, a person may use the alternate definitive statement: “Where it is necessary to seal a crack, joints, or other opening, AARST standards similar to SGM SF 2017 will be followed. Documentation of the type and location of the sealant used will be provided in the installation and commissioning documentation.”
2.3.6.2 Component labeling
This section should include the proposed labeling, example wording, and locations consistent with standards similar to AARST SGM-SF-2017. Alternatively, a person may use the statement: “Labels for the system will be developed and utilized as identified in AARST standards such as SGM SF 2017.”
2.3.6.3 Other specifications (if necessary)
Additional information can be provided in this section if the design firm believes that the information is critical to the success of the AVMS design and has not been included elsewhere in this document.
Key supporting information
- Figures, tables, or appendices may be provided as appropriate.
2.3.7 Barrier membrane (if proposed to be installed)
If a membrane will be installed as part of the AVMS, this section should provide information on the selected barrier and how it will be installed, including any oversight that will be performed. If a barrier membrane is necessary to meet performance metrics other than desired vacuum, the passive mitigation system design TOC should be reviewed for additional information that needs to be included in this section.
Key supporting information
- Figure(s) that detail the barrier installation.
- A separate appendix may be warranted to provide additional supporting information.
2.3.8 Preferential pathways and other unique features (if necessary)
This section should describe the mitigation strategy for any preferential pathways identified in Section 1.7 that need mitigation or additional considerations.
Key supporting information
- Figure(s) that detail each unique mitigation strategy for the identified preferential pathways.
2.3.9 Elevators and below grade pits or tunnels (if necessary)
This section should describe the mitigation strategy and how it will be effective for each elevator shaft, pit, sump, or tunnel that are part of the structure.
Key supporting information
- Figure(s) that detail each unique mitigation strategy for any elevator shafts, pits, or tunnels.
2.3.10 Vertical/sidewalls below grade (if necessary)
This section should describe the mitigation strategy for any vertical sidewall below grade where mitigation is necessary.
Key supporting information
- Figure(s) that detail the mitigation strategy for the vertical wall(s) below grade.
- Separate appendix, if necessary, to provide additional supporting information.
2.3.11 Groundwater in contact (if necessary)
If groundwater is in contact or may come into contact with the structure (see Section 1.4), this section should describe how the shallow groundwater will be addressed to allow for the proper function of the AVMS. If the AVMS will not include any mechanism to address groundwater that may come into contact with the lowest part of the structure, and there is not sufficient data from a nearby monitoring well to confirm that groundwater will not come into contact with the structure, then the monitoring that will be performed to confirm that the AVMS will remain effective should be described.
Key supporting information
- Figure(s) detailing the mitigation strategy for shallow groundwater.
- Separate appendix providing additional supporting information may be warranted.
2.3.12 Alarm and performance indicator (if proposed to be installed)
This section should describe any alarms and monitoring system(s) proposed as part of the AVMS and its function and purpose. The section should specify any warnings that will be relayed, if data is stored, and what documentation (if any) will be retained.
Note: Alarms and monitoring systems can provide immediate feedback on system operation and can be useful tools to utilize if high concentrations are present or where acute contaminants are located. Telemetric alarms may provide immediate feedback about the function of an AVMS to the owner/operator and record the data of the system operation which is a critical component of documenting compliance with an owner/operator’s obligations. Visual alarms require a person to physically observe some type of indicator and record if the AVMS is actually operating. Audible alarms may not require a person to physically observe whether the AVMS is operation but must be placed in a location that will be heard by building occupants.
Key supporting information
- Figure(s) that detail where the alarms will be installed.
2.4. Building codes and permits
This section should clearly state that permits necessary for the installation of the AVMS, which are not regulated by RRD, will be obtained, met, and complied with (e.g., building codes and air quality permits) through the following affirmative statement or similar: “The system will be installed and operated in accordance with all local, state, and federal laws and rules outside of RRD’s review and consideration, which includes but is not limited to, building codes and air quality regulations.”
2.5 Monitoring points and test ports
This section should describe the locations that are proposed to facilitate future confirmation of PFE effectiveness, system operation, and/or soil gas concentrations. It should also describe how the penetrations of the slab will be sealed in a permanent, airtight manner with appropriate materials and configuration to durably secure the test port in place. Additional information on the selection of the locations of the test ports can be found in ANSI/AARST SGM-SF 2017. Special consideration should be paid to placement of monitoring points within and around areas that may inhibit vacuum or flow due to features that extend beneath the floor slab, such as building footers, floor drains, trenches, elevator pits, collection pits, and utilities.
Key supporting information
- Figure(s) in plan view depicting the location of each monitoring point in relation to any suction point or subsurface AVMS component.
- Detailed figure(s) depicting how each type of monitoring or test point will be installed.