2.1 State Contingency Plan
...responses and responses to contaminated surface water, drinking water, outdoor air, soil vapor, or leaking underground tanks, the HEER Office may refer cases to or work closely with other ...
 

2.4 Environmental Cleanups
...environmental hazards (e.g., free product discharging into a surface water body or vapor intrusion into a building) and prepare an Environmental Hazard Management Plan to address ...
 

3.0 Site Investigation Design And Implementation
...levels of tetrachloroethylene in groundwater during a site investigation could suggest vapor intrusion as a potential environmental hazard (e.g., groundwater action level for vapor intrusion ...
 
...intrusion as a potential environmental hazard (e.g., groundwater action level for vapor intrusion exceeded). This could trigger the collection of soil gas samples in the source area ...
 
...could then lead to the need to seal floors in order to prevent the potential intrusion of vapors into the building. Linking the Site Investigation and Environmental Hazard Evaluation ...
 

3.2 Systematic Planning Of Site Investigation
...and nature of potential environmental hazards at a site (e.g., direct exposure, vapor intrusion, leaching to groundwater, etc.). The site investigation must be designed to meet ...
 
...2014), may not be adequate. The presence of other potential hazards such as leaching, vapor intrusion, gross contamination and ecotoxicity concerns must also be evaluated using ...
 
...a potential environmental hazard posed by volatile chemicals is the intrusion of vapors into existing or future buildings. The need to collect soil gas data should be evaluated ...
 
...gas data at sites where initial soil and/or groundwater data indicate potential vapor intrusion hazards. Analysis of soil samples that exceed 24 milligrams ...
 
...pose a threat to groundwater resources or is highly volatile and could pose potential vapor intrusion hazards for buildings (e.g., water-soluble pesticides, solvents, light-end petroleum ...
 
...the optimal area and depth of the DUs to evaluate potential exposure, leaching, vapor intrusion and/or gross contamination concerns? What is the optimal area ...
 
... How many soil gas samples are required to adequately assess potential vapor intrusion hazards? Is the collection of sorbent tube samples for TO-17 ...
 
...Do reported concentrations of COPCs in soil or groundwater data present potential vapor intrusion concerns, indicating the need for soil gas or indoor air sampling data (Section ...
 

3.3 Conceptual Site Models
...exposure to impacted soil (ingestion, dermal absorption, inhalation of vapors and dust in outdoor air); Emission of subsurface vapors to building interiors; ...
 
...and dust in outdoor air); Emission of subsurface vapors to building interiors; Leaching and contamination of groundwater ...
 
... ecotoxicity); Gross contamination conditions (explosive subsurface vapor conditions, odors, general resource degradation, etc.); Contaminated ...
 
...water resources (toxicity, taste and odors); Emission of subsurface vapors to building interiors; Discharges of contaminated groundwater ...
 
...conditions); Gross contamination conditions (generation of explosive vapors from free product, odors, sheens, general resource degradation, etc.). ...
 
... site conditions but could pose a threat under future conditions (e.g., potential vapor intrusion hazards identified but no buildings currently on site; refer to Section 13 and ...
 
... purposes, with contaminated soil covered by existing buildings and pavements and no vapor intrusion concerns). Contaminant concentrations at the site could, however, indicate a ...
 
... (along with other relevant information): Additional soil, soil vapor or groundwater data; Location of existing monitoring wells ...
 

3.4 Selection Of Decision Units
...generally necessary to evaluate environmental hazards associated with soil leaching, vapor intrusion and gross contamination hazards (see Step 8 in Subsection 3.2 and ...
 
... 2011b). If the target contaminant at the site poses leaching, vapor intrusion and gross contamination hazards, then the spill area should be designated as ...
 
...including leaching of contamination to subsurface groundwater resources, intrusion of vapors into overlying buildings and nuisance or even explosion hazards associated with grossly ...
 

3.6 Sampling And Analysis Plans
...method procedural guidance for soil and sediment, groundwater and surface water, and soil vapor and indoor air is presented in Sections 5, 6, and 7, respectively. The application ...
 

3.9 Site Investigation Reports
...that additional data be collected at the site (e.g., soil gas data to evaluate potential vapor intrusion concerns) or that additional tests be carried out on existing samples. After all ...
 

3.10 Environmental Hazard Evaluation
...report. In the absence of obvious conditions in the field (e.g., explosive levels of soil vapors), the most expeditious approach to identifying potential environmental hazards associated ...
 
...that batch testing and/or groundwater data may be needed. The identification of potential vapor intrusion concerns suggests that soil gas data are needed. Applying this type of ...
 

4.2 Use Of Multi Increment Samples To Characterize DUs
...by the concurrent or followup collection of groundwater (Section 6) and/or soil vapor samples (see Section 7). Volatile chemicals primarily pose potential leaching and/or ...
 
... Section 7). Volatile chemicals primarily pose potential leaching and/or vapor intrusion hazards. These concerns can be more directly addressed through testing of groundwater ...
 
...These concerns can be more directly addressed through testing of groundwater and soil vapors. 4.2.4 INCREMENT DISTRIBUTION ...
 
...For the purposes of this Section, a chemical is considered to be semi-volatile if its vapor pressure is between 0.1 and 1.0 mm Hg or if it is a liquid at 25ºC or if the Henry’s Law ...
 
...collection are acceptable for air drying (if needed) even when determining higher vapor pressure SVOCs. This and other alternative approaches should be discussed with the HEER ...
 
...is considered to be volatile if the molecular weight is less than 200 and the vapor pressure is greater than 1 mm Hg (25ºC) or the Henry’s Law Constant is greater than 0.00001 ...
 
... chemicals. Primary environmental hazards posed by VOC-contaminated soil include vapor intrusion, leaching and gross contamination hazards. This normally requires that spill ...
 
...Soil gas data are much more reliable than soil data for evaluating potential vapor intrusion hazards associated with volatile contaminants in soil (and groundwater). Soil ...
 

5.6 Collection Of Multi Increment Samples For VOC Analysis
... increments for MI samples are collected in separate sampling devices that have vapor tight seals and are designed for zero headspace (e.g. Core N� One™, EnCore™, ...
 
...sample collection (see Section 11.2). Note that to freeze samples in small cores with vapor-tight seals to temperatures between -7°C and -15°C (for temporary storage and shipping) ...
 

5.8 Field Documentation
...could be indicative of solvent compounds. Use of a field organic vapor analyzer for screening purposes is recommended when volatile or semi-volatile organic contaminants ...
 

6.0 Groundwater and Surface Water Sampling Guidance
...as part of a larger investigation that also involves subsurface soil sampling and/or soil vapor sampling. In either case, the initial site preparation and boring/drilling methods described ...
 

6.5 Groundwater Sample Collection Methods
... previous sampling events. If the order is not known from previous sampling events, use vapor readings collected at the top of the well casing to aid in determining the correct order. This ...
 

7.0 Soil Vapor and Indoor Air Sampling Guidance
... ' SECTION 7 SOIL VAPOR AND INDOOR AIR SAMPLING GUIDANCE Interim Final - February 2014 ...
 

Contents
... 7.1 Occurrence of Subsurface Vapor Plumes   ...
 
... 7.2 Soil Vapor Transport Mechanisms and Conceptual Site Models ...
 
... 7.2.1 Factors Affecting Subsurface Vapor Flow and Impacts to Indoor Air   ...
 
... 7.2.2 Preparation of Conceptual Site Models for Soil Vapor Investigations   ...
 
... 7.3 Development of Vapor Intrusion Screening Tools   ...
 
... 7.4 Soil Vapor Investigations   ...
 
... 7.5 Collection of Representative Soil Vapor Samples   ...
 
... 7.6 Soil Vapor Sampling Strategies   ...
 
... 7.6.1 Determining When to Collect Soil Vapor Samples   ...
 
... 7.6.2 Soil Vapor Sampling Design   ...
 
... 7.6.2.2 Soil Vapor Sampling Point Locations   ...
 
... 7.6.2.3 Soil Vapor Sample Depths and Depth Intervals   ...
 
... 7.6.2.4 Soil Vapor Sample Screen Intervals   ...
 
... 7.8.3.1 Passive Soil Vapor Sample Collectors   ...
 
... 7.9 Active Soil Vapor Probe Installation   ...
 
... 7.9.4 Soil Vapor Probe Tubing   ...
 
... 7.9.5 Soil Vapor Probe Abandonment   ...
 
... 7.10 Active Soil Vapor Sampling Procedures   ...
 
... 7.10.1 Soil Vapor Sample Timing and Frequency   ...
 
... 7.10.2 Soil Vapor Probe Equilibration   ...
 
... 7.10.3 Soil Vapor Probe Purging   ...
 
... 7.10.4 Soil Vapor Sampling Trains   ...
 
... 7.10.5 Soil Vapor Probe Leak Testing   ...
 
... 7.10.5.2 Water Dam Vapor Point Test   ...
 
... 7.10.6 soil vapor sample collection steps   ...
 
... 7.10.7 Soil Vapor Sample Notes and Logs   ...
 
... 7.12 Passive Soil Vapor and Indoor Air Sample Collection Procedures ...
 
... 7.12.1 Passive Sampling of Soil Vapor   ...
 
... 7.13 Soil Vapor And Indoor Air Sample Analysis   ...
 
... 7.14.1 Soil Vapor Sample Evaluation   ...
 
... 7.15 Documentation of Soil Vapor or Indoor Air Sampling   ...
 
... 7-1. Example Vapor Plume Contours and Vapor Intrusion Pathways. ...
 
...Plume Contours and Vapor Intrusion Pathways.   ...
 
... 7-2 Conceptual Model of Soil Vapor Transport Including Biodegradation Process. ...
 
... 7-3 Complete Exposure Pathway CSM for Soil Vapor to Indoor Air.   ...
 
... 7-4 Schematic of Soil Vapor Concentration Profile.   ...
 
... 7-10 Two Examples of Passive Soil Vapor Sample Collectors.   ...
 
... 7-14 Typical Temporary Soil Vapor Probe   ...
 
... 7-15 Installing a Temporary Soil Vapor Probe Using a Direct-Push Drill Rig ...
 
... 7-16 Vapor Point Completions   ...
 
... 7-17 Typical Nested Permanent Soil Vapor Sampling Probes   ...
 
... 7-18 Installation of a Permanent Soil Vapor Probe   ...
 
... 7-19 Schematic of Typical Sub-Slab Soil Vapor Sampling Probe (see also Figure 7-20 & 7-21). ...
 
... 7-20 Sub-Slab Soil Vapor Sampling Probes   ...
 
... 7-21 Sub-Slab Soil Vapor Sampling Probes   ...
 
... 7-22 Installation of a Vapor Pin™ with a silicon sleeve directly into slab ...
 
... 7-23 Soil Vapor Probe Purging Devices   ...
 
...Tedlar bag. Vacuum is drawn on sealed lung box, causing the Tedlar bag to pull vapor from the collection point and fill. ...
 
... 7-27. Example Soil Vapor Sample Collection Setups   ...
 
... 7-28 Soil Vapor Sampling Trains Arranged for Shut-in Test (see also Figure 7-27) ...
 
..."Water Dam" Sealed to Floor with Inert Putty for Leak Testing Slab-mounted Vapor Point   ...
 
... 7-30 Shroud Over Vapor Probe Surface Completion   ...
 
... 7-33 Installing a Passive Soil Vapor Sample Collector by Hand.   ...
 
... 7-34 Example Plume Map from Grid-based Passive Soil Vapor Survey.   ...
 
... 7-1 Decision Logic for Subsurface Vapor Hazards   ...
 
... 7-3 Comparison of Soil Vapor & Indoor Air Sampling Approaches ...
 
... 7-4 Common Soil Vapor Concentration Unit Conversion Factors ...
 
... 7-10 Summary of Soil Vapor & Indoor Air Analytical Methods1 ...
 
... HDOH-Recommended Laboratory Analytical Methods for Soil Vapor or Indoor Air Contaminants and Leak Detection Compounds ...
 

7.0 Soil Vapor and Indoor Air Sampling Guidance
... ' 7.0 SOIL VAPOR AND INDOOR AIR SAMPLING GUIDANCE This section of the Technical Guidance Manuall ...
 
...section of the Technical Guidance Manuall addresses the collection of subsurface soil vapor samples and indoor air samples. The guidance was developed following review of numerous guidance ...
 
...of sample collection is preceded by an overview of the occurrence and nature of vapor plumes in the subsurface and the potential risks posed to outdoor air and overlying buildings. ...
 
... air and overlying buildings. The development of HDOH soil, groundwater and soil gas (�vapors�) action levels for evaluation of vapor intrusion hazards is described in the document Evaluation ...
 
...action levels for evaluation of vapor intrusion hazards is described in the document Evaluation of Environmental Hazards at Sites ...
 

Figures
... 7-1. Example Vapor Plume Contours and Vapor Intrusion Pathways. ...
 
...Plume Contours and Vapor Intrusion Pathways.   ...
 
... 7-2 Conceptual Model of Soil Vapor Transport Including Biodegradation Process. ...
 
... 7-3 Complete Exposure Pathway CSM for Soil Vapor to Indoor Air.   ...
 
... 7-4 Schematic of Soil Vapor Concentration Profile.   ...
 
... 7-10 Two Examples of Passive Soil Vapor Sample Collectors.   ...
 
... 7-14 Typical Temporary Soil Vapor Probe.   ...
 
... 7-15 Installing a Temporary Soil Vapor Probe Using a Direct-Push Drill Rig. ...
 
... 7-16 Vapor Point Completions.   ...
 
... 7-17 Typical Nested Permanent Soil Vapor Sampling Probes.   ...
 
... 7-18 Installation of a Permanent Soil Vapor Probe.   ...
 
... 7-19 Schematic of Typical Sub-Slab Soil Vapor Sampling Probe (see also Figure 7-20 & 7-21). ...
 
... 7-20 Sub-Slab Soil Vapor Sampling Probes.   ...
 
... 7-21 Sub-Slab Soil Vapor Sampling Probes.   ...
 
... 7-22 Installation of a Vapor Pin™ with a silicon sleeve directly into slab. ...
 
... 7-23 Soil Vapor Probe Purging Devices.   ...
 
...bag. Vacuum is drawn on sealed lung box, causing the Tedlar bag to pull vapor from the collection point and fill. ...
 
... 7-27. Example Soil Vapor Sample Collection Setups.   ...
 
... 7-28 Soil Vapor Sampling Trains Arranged for Shut-in Test (see also Figure 7-27). ...
 
..."Water Dam" Sealed to Floor with Inert Putty for Leak Testing Slab-mounted Vapor Point.   ...
 
... 7-30 Shroud Over Vapor Probe Surface Completion.   ...
 
... 7-33 Installing a Passive Soil Vapor Sample Collector by Hand.   ...
 
... 7-34 Example Plume Map from Grid-based Passive Soil Vapor Survey.   ...
 

Tables
... 7-1 Decision Logic for Subsurface Vapor Hazards   ...
 
... 7-3 Comparison of Soil Vapor & Indoor Air Sampling Approaches. ...
 
... 7-4 Common Soil Vapor Concentration Unit Conversion Factors. ...
 
... 7-10 Summary of Soil Vapor & Indoor Air Analytical Methods. ...
 
... HDOH-Recommended Laboratory Analytical Methods for Soil Vapor or Indoor Air Contaminants and Leak Detection Compounds. ...
 

7.1 Soil Vapor Transport Mechanisms and Conceptual Models
... ' 7.1 OCCURRENCE OF SUBSURFACE VAPOR PLUMES Sites where releases of volatile organic compounds (VOCs) can be of concern ...
 
...of volatile chemicals from contaminated soil and groundwater can create a plume of vapors in the vadose zone. These plumes can adversely impact indoor air if drawn into an overlying ...
 
...impact indoor air if drawn into an overlying building, a key topic of this section. Vapors emitted at the ground surface can also affect outdoor air. This issue is addressed separately ...
 
...soil, however, and is considered to pose less of a threat to human health than vapor intrusion into buildings (see HDOH 2011). Vapors in vadose-zone soil could also migrate downwards ...
 
...intrusion into buildings (see HDOH 2011). Vapors in vadose-zone soil could also migrate downwards and impact groundwater that has otherwise ...
 
...at MTBE release sites on the mainland. The majority of subsurface vapor plumes in Hawai�i are associated with subsurface released petroleum fuels including gasoline, ...
 
...petroleum fuels including gasoline, diesel and jet fuel. As discussed in Section 7.13, vapors emitted from petroleum fuels are evaluated in terms of Total Petroleum Hydrocarbons (TPH) ...
 
...can also be of importance at some sites. As discussed in Section 7.6, petroleum-related vapor plumes that could pose hazards for overlying buildings are almost always associated with ...
 
... of petroleum compounds by naturally occurring bacteria in the soil will ensure that vapor plumes rarely migrate more than 15 to 30 feet vertically through unconsolidated soil and more ...
 
...the source area (see Section 7.6.1). A smaller number of subsurface vapor plumes in Hawai�i are associated with releases of chlorinated solvents from dry cleaners (e.g., ...
 
...tetrachloroethene or �PCE�) or parts washing operations (e.g., trichloroethene or �TCE�). Vapors emitted from these releases are evaluated in terms of the primary product released as well ...
 
...and in particular the greater persistence of chlorinated solvents can lead to potential vapor intrusion concerns even in the absence of free product in soil or groundwater. Dilute plumes ...
 
...period of operation. The presence of high levels of vinyl chloride in groundwater or soil vapor at sites often indicates the presence of co-located petroleum contamination. The vinyl chloride ...
 
... in the presence of petroleum. The presence of significant breakdown products in soil vapor or groundwater signifies the need to look for petroleum contamination in the same area. ...
 
... in the same area. Due to the inherent heterogeneity of VOCs in subsurface vapor plumes and the uncertainty of upward vapor migration from deeper areas, HDOH emphasizes the ...
 
...plumes and the uncertainty of upward vapor migration from deeper areas, HDOH emphasizes the collection of soil vapor samples from immediately ...
 
...migration from deeper areas, HDOH emphasizes the collection of soil vapor samples from immediately beneath a building slab for evaluation of potential vapor intrusion ...
 
...samples from immediately beneath a building slab for evaluation of potential vapor intrusion hazards (see Section 7.6.2.3). The concurrent collection and evaluation of deeper ...
 
...hazards (see Section 7.6.2.3). The concurrent collection and evaluation of deeper soil vapor samples is also typically recommended for heavily-contaminated properties. Data from deeper ...
 

7.2 Soil Vapor Intrusion to Indoor Air
... ' 7.2 SOIL VAPOR TRANSPORT MECHANISMS AND CONCEPTUAL SITE MODELS 7.2.1 Factors Affecting Subsurface ...
 
...AND CONCEPTUAL SITE MODELS 7.2.1 Factors Affecting Subsurface Vapor Flow and Impacts to Indoor Air As introduced in the previous section, understanding ...
 
...to Indoor Air As introduced in the previous section, understanding how vapors are generated, migrate in the subsurface and can intrude an overlying building is important ...
 
... (e.g., see USEPA 2004e). In practice, estimation of the upward, mass flux of vapor-phase VOCs in the subsurface and prediction of VOC concentrations in subslab soil vapor is ...
 
...VOCs in the subsurface and prediction of VOC concentrations in subslab soil vapor is very difficult. Figure 7-1: Example Vapor ...
 
...is very difficult. Figure 7-1: Example Vapor Plume Contours and Vapor Intrusion Pathways. Vapor-phase chemicals diffuse away from a ...
 
...Plume Contours and Vapor Intrusion Pathways. Vapor-phase chemicals diffuse away from a source area. Wind effects ...
 
...Intrusion Pathways. Vapor-phase chemicals diffuse away from a source area. Wind effects (or heating) can cause depressurization ...
 
...(or heating) can cause depressurization of buildings and advective intrusion of vapors. Air conditioning (AC) can over pressurize a building as fresh air is brought inside and ...
 
...of air into the subslab space. Source: Modified from API 2005. Upward migration of vapors dominated by diffusion; advective flow limited to near vicinity (a few feet or less) ...
 
...buildings. Concentrations of VOCs in shallow or subslab soil vapor are oftentimes significantly lower than would be predicted by models based on the soil type ...
 
...field (see HDOH 2011, USEPA 2012). This is probably due in part to adsorption of vapor-phase VOCs to clays in the soil and permanent removal from the vapor plume, a mechanism not ...
 
...VOCs to clays in the soil and permanent removal from the vapor plume, a mechanism not directly taken into account in the vapor intrusion models used to generate ...
 
...plume, a mechanism not directly taken into account in the vapor intrusion models used to generate the HDOH soil gas (�vapor�) action levels. This is also due ...
 
...intrusion models used to generate the HDOH soil gas (�vapor�) action levels. This is also due to the heterogeneous nature of contaminant distribution, ...
 
...the collection of representative data. These factors highlight the need to collect soil vapor data in the immediate vicinity of potentially affected buildings as a routine part of vapor ...
 
...data in the immediate vicinity of potentially affected buildings as a routine part of vapor intrusion studies when general site knowledge suggest a potentially significant vapor intrusion ...
 
...intrusion studies when general site knowledge suggest a potentially significant vapor intrusion risk. Vapors migrate in subsurface soils primarily by diffusion ...
 
...intrusion risk. Vapors migrate in subsurface soils primarily by diffusion from high- to low-concentration areas (Figure ...
 
...soils primarily by diffusion from high- to low-concentration areas (Figure 7-1). Vapors diffuse much more rapidly through air-filled pore space than water-filled pore space. Advective ...
 
... through air-filled pore space than water-filled pore space. Advective flow of vapors caused by pressure differentials (e.g., flow from high- to low-pressure areas) can occur in ...
 
...USEPA 2012d). Wind-induced depressurization of buildings will be the most likely cause of vapor intrusion in Hawai�i. Wind can create a low-pressure zone on the downwind side of a building. ...
 
...Air pulled out of the building as a result can lead to the advective flow of subsurface vapors through cracks and gaps in the floor. This is taken into account in building and HVAC system ...
 
...of indoor air into subslab soils (see also USEPA 2012d). Samples of subslab soil vapor would in turn reflect the concentration of VOCs in indoor air samples, rather than a subsurface ...
 
...than a subsurface source. This presumably explains the apparent absence of significant vapors immediately beneath slabs of air-conditioned buildings that overlie shallow, petroleum free ...
 
... contaminated soil. In this case, the sudden, upward �attenuation� of deeper soil vapors in the immediate vicinity of a building slab is not attributable to biodegradation. ...
 
...slab is not attributable to biodegradation. Note that an upward diffusion of vapors into the subslab area could also occur when the air conditioning is turned off in the night ...
 
...has not been studied in detail. In theory, this could lead to the intrusion of subsurface vapors into the building during these time periods. In practice, this is likely to be offset by the ...
 
...time periods. In practice, this is likely to be offset by the time required for deeper vapors contaminants to diffuse into the zone of advective transport. Impacts to indoor air by intruding ...
 
...to diffuse into the zone of advective transport. Impacts to indoor air by intruding vapors are also likely to be offset by increased impacts from indoor sources (see Section ...
 
...on a site-specific basis, however, at sites considered to be of high risk for potential vapor intrusion. Concentrations of volatile chemicals in indoor air associated with indoor ...
 
...with operation of the building HVAC system are important to recognize as part of a vapor intrusion investigation and to consider when determining the timing and frequency of sample ...
 
... Section 7.11, if indoor air samples are desired or required to further assess potential vapor intrusion hazards then they should be collected under normal building ventilation and operation ...
 
... Figure 7-2: Conceptual Model of Soil Vapor Transport Including Biodegradation Process. Source: Adapted from API 2005. Note hypothetical ...
 
...hypothetical anaerobic zone immediately beneath the building due to biodegradation of vapor-phase petroleum compounds and inadequate replenishment of oxygen. ...
 
...reached groundwater. As the water table falls and exposes this smear zone, an increase in vapor emissions can occur. As the water table rises some product may rise with it and continue to ...
 
...can occur. As the water table rises some product may rise with it and continue to pose vapor emission hazards. A substantial portion is likely to remain trapped in the smear zone below ...
 
...smear zone below the water table, however. This can result in a substantial reduction in vapor emissions during the wet season. The collection of deep and/or subslab soil vapor samples during ...
 
...emissions during the wet season. The collection of deep and/or subslab soil vapor samples during both the wet and dry season is, recommended for sites where exposure of a significant ...
 
...and fall of the water table with fluctuating tides could also influence the migration of vapors in the vadose zone. Indoor air could be pulled out of the building and into the subslab zone ...
 
...Hawai�i, typically less than one-foot, are unlikely to cause significant fluctuations in vapor concentrations due to exposure and flooding of smear zones. Tidal pumping of air into and out ...
 
...a well-oxygenated zone under a building slab and help protect against significant vapor intrusion associated with subsurface, petroleum contamination. As discussed in ...
 
...pumping is not necessary for general screening purposes. The collection of subslab soil vapor samples during periods of both falling and rising water table may be recommended or required, ...
 
... contamination. 7.2.2 Preparation of Conceptual Site Models for Soil Vapor Investigations Consideration of subsurface vapors and the potential for soil vapor ...
 
...Investigations Consideration of subsurface vapors and the potential for soil vapor intrusion should be included in an overall conceptual site ...
 
...and the potential for soil vapor intrusion should be included in an overall conceptual site model (CSM) and used to design sampling ...
 
...reflect the representative, average subsurface conditions and building susceptibility to vapor intrusion over time and during normal building operation. This is important, because the soil ...
 
... TPH) to thirty-year time period (cancer risk; e.g., benzene and PCE). A focus on soil vapor samples collected during periods of high water table or vapor flux assumptions during periods ...
 
...samples collected during periods of high water table or vapor flux assumptions during periods when a building is over-pressurized can lead to the underestimation ...
 
...periods when a building is over-pressurized can lead to the underestimation of potential vapor intrusion hazards. A focus on subsurface data collected during periods of low water table or ...
 
...low water table or periods when the building is under-pressured and most susceptible to vapor intrusion could overestimate the actual risk and lead to unnecessary remedial actions. An understanding ...
 
...of the CSM is therefore very important. A simple conceptual model of soil vapor transport includes the outward diffusion of vapor-phase chemicals from impacted soil or groundwater ...
 
...transport includes the outward diffusion of vapor-phase chemicals from impacted soil or groundwater and the potential advective flow of the vapors ...
 
...chemicals from impacted soil or groundwater and the potential advective flow of the vapors into an overlying building (Figure 7 1). The chemicals could migrate to and intrude residential ...
 
...migrate to and intrude residential or commercial/industrial building interiors. Common vapor intrusion pathways into buildings include basements, crawl spaces, cracks, and utility penetrations ...
 
... crawl spaces, cracks, and utility penetrations in concrete slabs. The intruding vapors subsequently mix with indoor air and the concentration of initial chemicals in the vapors ...
 
...subsequently mix with indoor air and the concentration of initial chemicals in the vapors is attenuated. Figure 7-3: Complete Exposure ...
 
... Figure 7-3: Complete Exposure Pathway CSM for Soil Vapor to Indoor Air. A more detailed conceptual model of soil vapor transport ...
 
...to Indoor Air. A more detailed conceptual model of soil vapor transport might consider spatial temporal variations in subsurface conditions and building ...
 
... Brewer et al. 2014, in prep). This factor and uncertainty regarding specific, vapor entry routes complicates the investigation of potential vapor intrusion hazards. As discussed ...
 
...entry routes complicates the investigation of potential vapor intrusion hazards. As discussed in Section 7.6.2.2, the biased collection of subslab ...
 
...hazards. As discussed in Section 7.6.2.2, the biased collection of subslab soil vapor samples from center of slabs, presumed to be the worst-case area for vapor accumulation as ...
 
...samples from center of slabs, presumed to be the worst-case area for vapor accumulation as well as potential vapor entry points in other areas of the building (e.g., ...
 
...accumulation as well as potential vapor entry points in other areas of the building (e.g., cracks in floor and utility gaps) is recommended. ...
 
...as daughter products). These conditions could change over time, as the release ages. The vapor transport of daughter products, oxygen, CO2, and in the case of petroleum hydrocarbons, methane, ...
 
...aerobic or anaerobic biodegradation processes. The exposure pathway for soil vapor should be included on the CSM, which serves as the basis of an exposure assessment (see HDOH ...
 
...the chemicals of concern. An example of a complete exposure pathway CSM diagram for soil vapor to indoor air is provided in Figure 7-3. For the chemicals of concern ...
 
...present a means of exposure under the conditions assumed in the CSM. Common pathways for vapor intrusion from the subsurface are cracks or utility penetrations through the slab or basement ...
 
...Bathrooms, kitchens and utility rooms are often the primary entry points for intruding vapors. As discussed in Sections 7.6.2 and 7.10.1, it is important that ...
 
...prepared prior to an investigation and used to help determine the number and location of vapor collection points as well as the frequency and timing of sample collection. See ...
 
...7.14 discusses the use of a multiple-lines-of-evidence approach to evaluate potential vapor intrusion hazards on a site-specific basis for cases where a high risk of vapor intrusion is ...
 
...intrusion hazards on a site-specific basis for cases where a high risk of vapor intrusion is identified. ...
 

7.3 Characterization, Delineation and Monitoring
... ' 7.3 DEVELOPMENT OF VAPOR INTRUSION SCREENING TOOLS Assumptions regarding the local nature of vapor intrusion ...
 
...INTRUSION SCREENING TOOLS Assumptions regarding the local nature of vapor intrusion and building ventilation can be used to develop environmental action levels for rapid ...
 
...screening of suspect sites. Development of the HDOH soil, groundwater and soil gas (�vapor�) action levels for vapor intrusion is discussed in the HDOH EHE guidance document ((HDOH ...
 
...action levels for vapor intrusion is discussed in the HDOH EHE guidance document ((HDOH 2011; see also PBEHE 2012). ...
 
...study entitled Field Investigation of the Chemistry and Toxicity of TPH in Petroleum Vapors: Implications for Potential Vapor Intrusion Hazards (HDOH 2012). The results of this study ...
 
...Implications for Potential Vapor Intrusion Hazards (HDOH 2012). The results of this study were incorporated into ...
 
...the EHE guidance, the selected attenuation factors and associated HDOH action levels for vapor intrusion may not be adequately conservative for use in colder regions on the US mainland and ...
 
...the US mainland and elsewhere. Adjustment of the action levels to assumptions regarding vapor flux and building ventilation is required and should be discussed with the overseeing regulatory ...
 

7.4 Soil Vapor Probe Installation
... ' 7.4 SOIL VAPOR INVESTIGATIONS The remainder and primary part of this section then focuses on the ...
 
...and primary part of this section then focuses on the collection and analysis of soil vapor and indoor air samples. Although the guidance presented is anticipated to apply under most ...
 
...should be discussed with the overseeing HDOH project manager. Soil vapor and less commonly indoor air samples are collected following the discovery or identification ...
 
...volatile or semi-volatile constituents. In addition to the evaluation of potential vapor intrusion hazards, uses of soil vapor or indoor air sample data include: 1) Characterization ...
 
... intrusion hazards, uses of soil vapor or indoor air sample data include: 1) Characterization and delineation of contamination, 2) ...
 
...actions, 3) Assessment of worker-related environmental hazards in locations where soil vapor may accumulate, such as under foundations, roadways and caps, and in utility conduits ...
 
... appropriate remedial actions. As discussed later in this guidance, soil vapor samples should be representative of in situ, static conditions at a site. The collection of ...
 
...should be representative of in situ, static conditions at a site. The collection of soil vapor samples should be carried out in a manner that minimizes stripping of VOCs from free product ...
 
...sorbed to soil particles or dissolved in groundwater and not initially present in the vapor phase. This is accomplished primarily by minimizing the vacuum imposed on the soils during ...
 
... primarily by minimizing the vacuum imposed on the soils during the collection of active vapor samples (see Section 7.8.3.2). The collection of soil vapor samples is not intended to mimic ...
 
...samples (see Section 7.8.3.2). The collection of soil vapor samples is not intended to mimic advective flow of vapors through the vadose zone and hypothetical, ...
 
...samples is not intended to mimic advective flow of vapors through the vadose zone and hypothetical, additional stripping of VOCs in product, ...
 
...studying approaches for the collection of representative and more cost-effective vapor samples at these types of sites. The spatial and temporal heterogeneity of subsurface vapor ...
 
...samples at these types of sites. The spatial and temporal heterogeneity of subsurface vapor plumes in particular has been very poorly studied. The fact that discrete soil samples can ...
 
... that a similar problem most likely occurs with the collection of �discrete� soil vapor samples (�false negatives�; refer to Section 3). Discrete soil vapor samples could also over-estimate ...
 
...samples (�false negatives�; refer to Section 3). Discrete soil vapor samples could also over-estimate mean vapor concentrations beneath a building and the associated ...
 
...samples could also over-estimate mean vapor concentrations beneath a building and the associated vapor intrusion threat (�false positives�). ...
 
...concentrations beneath a building and the associated vapor intrusion threat (�false positives�). Parties are invited to discuss alternative approaches ...
 
...alternative approaches for the collection of more representative and cost-effective soil vapor samples with HDOH. The information provided in this section is intended to apply ...
 
...provided in this section is intended to apply to sites in the State of Hawai`i where soil vapor and, if required, indoor air samples are collected, whether the evaluation is being conducted ...
 
...technically defensible and consistent approach for the collection and evaluation of soil vapor or indoor air samples. However, this guidance is not regulation and is only meant to provide ...
 
...is only meant to provide a clear technical framework for collecting and evaluating soil vapor or indoor air samples. The information contained in this guidance is not intended to exclude ...
 
...efforts to prevent fires or explosions resulting from the accumulation of hazardous vapors (i.e., methane); however, methane concentrations should be monitored to determine whether ...
 
...actions by qualified responders should be completed prior to the initiation of a soil vapor or indoor air sampling event. If the results from the soil vapor or indoor air sampling event ...
 
...or indoor air sampling event. If the results from the soil vapor or indoor air sampling event indicate that there is an immediate concern for human exposures ...
 
...air sampling event indicate that there is an immediate concern for human exposures to vapor phase chemicals, then emergency response or interim actions are typically implemented as required ...
 
... under state and federal regulations. The HEER Office recommends that Soil Vapor or Indoor Air sampling work plans be submitted for review and approval prior to the collection ...
 
...sampling work plans be submitted for review and approval prior to the collection of soil vapor or indoor air samples in Hawai`i. The work plan should describe the purpose and rationale ...
 
...samples in Hawai`i. The work plan should describe the purpose and rationale for the soil vapor or indoor air sampling, targeted chemicals of concern, sample locations and depths, sample ...
 

7.5 Soil Vapor Or Indoor Air Sampling Methods
... ' 7.5 COLLECTION OF REPRESENTATIVE SOIL VAPOR SAMPLES The previous section outlined factors that could control the concentration ...
 
... The previous section outlined factors that could control the concentration of vapors in the subsurface and immediately beneath the slab of an overlying building. As discussed, ...
 
...the slab of an overlying building. As discussed, the collection of representative soil vapor samples for evaluation of potential vapor intrusion hazards is critical. Geologic factors that ...
 
...samples for evaluation of potential vapor intrusion hazards is critical. Geologic factors that control vapor concentrations in the subsurface ...
 
...intrusion hazards is critical. Geologic factors that control vapor concentrations in the subsurface and temporal variations that control vapor concentrations ...
 
... concentrations in the subsurface and temporal variations that control vapor concentrations over time must be considered when setting investigation objectives and collecting ...
 
...and collecting samples. Recommendations on the location, timing and frequency of soil vapor sample collection are presented in the following sections. Data associated ...
 
...are presented in the following sections. Data associated with discrete soil vapor samples are typically extrapolated over large distances and depths between individual sample ...
 
...Unit” area. The effect of subsurface heterogeneity on the representativeness of soil vapor samples has not been well studied but can be reasonably assumed to be less than recognized ...
 
...recognized for contaminants in soil, due to an assumed more efficient distribution of vapor-phase contaminants by diffusion through soil pore space. This would in theory allow the ...
 
...soil pore space. This would in theory allow the mean concentration of VOCs in soil vapor for a targeted area to be determined by a fewer number of samples (or “increments”) than for ...
 
... a fewer number of samples (or “increments”) than for soil. With respect to vapor intrusion, the ultimate objective of an investigation is to estimate the average concentrations ...
 
...objective of an investigation is to estimate the average concentrations of VOCs in soil vapor that will or could enter a building over a sustained, exposure duration of six years (noncarcinogens; ...
 
...thirty years (carcinogens; e.g., benzene and PCE). This requires the collection of soil vapor samples from the area of the subsurface, vapor plume most likely to contribute to vapor intrusion ...
 
...samples from the area of the subsurface, vapor plume most likely to contribute to vapor intrusion over the assumed, six- to thirty-year exposure ...
 
...plume most likely to contribute to vapor intrusion over the assumed, six- to thirty-year exposure duration. As is the case for soil, ...
 
...is generally not to identify the maximum concentration of VOCs present in soil vapors (i.e., acute exposure), although this may need to be considered on a site-specific basis. ...
 
... although this may need to be considered on a site-specific basis. The use of short vapor point screen lengths in an attempt to identify worst-case, non-representative “hot spots” (or ...
 
...samples collected in the field, and the lack of well-thought-out Decision Units in soil vapor investigations typically means that the maximum concentration of a chemical detected in samples ...
 
...and other risks. Additional guidance on the collection of representative soil vapor samples with respect to long-term, vapor intrusion concerns is currently being developed by ...
 
...samples with respect to long-term, vapor intrusion concerns is currently being developed by both the HDOH and other environmental agencies ...
 
...agencies and private entities in the US. Updates on the optimal number and volume of soil vapor samples will be incorporated into the TGM as available ...
 

7.6 Soil Vapor Sample Collection Procedures
... ' 7.6 SOIL VAPOR SAMPLING STRATEGIES 7.6.1 Determining When to Collect Soil Vapor Samples ...
 
...SAMPLING STRATEGIES 7.6.1 Determining When to Collect Soil Vapor Samples Subsurface soil vapor samples are collected to help locate and characterize ...
 
...Samples Subsurface soil vapor samples are collected to help locate and characterize areas of contaminated soil and groundwater ...
 
...large areas due to diffusion and groundwater flow. The additional collection of soil vapor samples to assist in the identification of areas of contaminated groundwater is typically not ...
 
...in the models and data used to develop the levels. The direct collection of soil vapor samples is recommended in these scenarios. Reliance on soil samples to adequately ...
 
...number of �hot spots� is minimal. The chemicals may also be present predominantly in vapor phase in very dry soil (e.g., beneath a dry cleaner building slab). This could be overlooked ...
 
...by the collection of only soil samples. The collection of soil vapor samples is therefore recommended at all sites where a significant amount of VOC-contaminated ...
 
...be present in the vadose-zone and/or the contaminant could be present primarily in the vapor phase. A soil volume of at least 10m3 is generally needed in order to pose significant, long-term ...
 
...soil volume of at least 10m3 is generally needed in order to pose significant, long-term vapor intrusion hazards, based on mass-balance models for assumed exposure duration and ...
 
...short-term, acute or nuisance impacts must also be considered. Direct collection of soil vapor samples regardless of soil and/or groundwater data is also recommended for sites with a very ...
 
...relatively large areas due to diffusion and to a lesser extent advective flow. A soil vapor sample is also representative of a significantly larger volume of soil (several liters) than ...
 
...sample (five grams, around three milliliters). This emphasizes the usefulness of soil vapor samples to identify the presence or absence of significant VOC contamination in the subsurface. ...
 
...could still miss significant areas of VOC-contaminated soil that might pose leaching or vapor intrusion hazards. Additional guidance on the use of soil vapor samples to help ...
 
...intrusion hazards. Additional guidance on the use of soil vapor samples to help evaluate potential leaching hazards at sites will be included in future editions ...
 
...TGM. In addition to the identification of subsurface VOC-contaminated soil, subsurface vapor samples are most commonly used to evaluate potential vapor intrusion hazards for existing ...
 
...samples are most commonly used to evaluate potential vapor intrusion hazards for existing or future buildings. The HEER Office recommends the following ...
 
...HEER Office recommends the following three-step approach for the initial evaluation of vapor intrusion hazards at sites where soil or groundwater is contaminated with volatile chemicals ...
 
...(HDOH 2011): Table 7-1 Decision Logic for Subsurface Vapor Hazards ...
 
... Soil Vapor Data ...
 
... Contaminants in Vadose Zone 2Soil and/or 3Groundwater Pose Potential Vapor Intrusion Hazards ...
 
... Collect source area vapor data and data to evaluate potential vapor intrusion hazards. ...
 
...data and data to evaluate potential vapor intrusion hazards. ...
 
... Collect source area vapor data to evaluate potential future vapor intrusion hazards or, at a minimum, ...
 
...data to evaluate potential future vapor intrusion hazards or, at a minimum, recommend soil vapor investigation prior ...
 
...intrusion hazards or, at a minimum, recommend soil vapor investigation prior to future subsurface work or construction of buildings. ...
 
... Post-Remediation Confirmation of Previously Identified Vapor Intrusion Hazard ...
 
... Collect soil vapor data to confirm and document absence of remaining, significant vapor intrusion ...
 
...data to confirm and document absence of remaining, significant vapor intrusion hazards. ...
 
... 4No Potentially Significant Vapor Intrusion Hazards Identified ...
 
... Collection of soil vapor samples not necessary; conclude in EHE that contamination does not pose significant ...
 
...necessary; conclude in EHE that contamination does not pose significant vapor intrusion hazards. ...
 
... VOC concentrations above Tier 1 soil action levels for vapor intrusion, significant volume (e.g., >10m3) of VOC-contaminated soil is present, ...
 
...(e.g., >10m3) of VOC-contaminated soil is present, or potential for elevated vapors under a building slab otherwise suspected (e.g., PCE vapors under a dry cleaner). ...
 
...under a building slab otherwise suspected (e.g., PCE vapors under a dry cleaner). Free product on groundwater table or dissolved ...
 
...table or dissolved VOC concentrations above Tier 1 groundwater action levels for vapor intrusion. VOC concentrations below Tier 1 EALs for both soil or groundwater ...
 
... >10m3) of VOC-contaminated soil or other potential source of elevated vapors under a building slab not suspected. Compare groundwater ...
 
...in Appendix 1 of the EHE document; or use the EAL surfer. Collect soil vapor samples immediately beneath building slab or within crawl spaces (preferred), or ...
 
...Action Levels for areas over or near a plume where Groundwater and/or Soil EALs for vapor intrusion are approached or exceeded or sites where a potentially significant source area ...
 
... see also HDOH 2011, Table C-2 in Appendix 1). Collection of soil vapor samples from source areas is recommended if widespread, heavy contamination is known to ...
 
...Section 7.6.2.3). In the case of anticipated future construction, collection of soil vapor samples from the future building footprint is strongly recommended. Recommended sampling ...
 
...to existing structures are discussed in the following section. Note that soil vapor samples are recommended at sites where significant amounts of VOC-contaminated soil may ...
 
...include sealing of floors and active treatment of source areas or the installation of vapor barriers under future buildings. Consider the collection of indoor air samples if the concentration ...
 
... Consider the collection of indoor air samples if the concentration of a VOC in vapors immediately beneath a building slab exceeds the soil gas action level and ...
 
... Table 7-1 provides the decision logic for determining when soil vapor sampling is recommended (Step 2) based on the occurrence of VOCs in soil and/or groundwater ...
 
...the building and the source area. The initial collection of soil vapor samples will generally focus on source area and immediately under overlying or nearby buildings. ...
 
...from a subsurface source area is considered adequate to prevent potentially significant vapor intrusion problems (ITRC 2007). The adequate vertical separation distance is highly site and ...
 
...and contaminant specific. Vertical separation distances appropriate for attenuation of vapors associated with chlorinated solvents have not been adequately studied. ...
 
...of sediment, etc., can lead to the presence of clay-rich moist units with very low vapor permeability that significantly impede the upward diffusion of vapors (diffusion rates through ...
 
...permeability that significantly impede the upward diffusion of vapors (diffusion rates through water are typically four orders-of-magnitude slower than through ...
 
...EHE guidance, HDOH 2011). Thin lenses of perched groundwater can further reduce upward vapor flux. Aerobic biodegradation of non-chlorinated, vapor-phase, petroleum compounds can also ...
 
...flux. Aerobic biodegradation of non-chlorinated, vapor-phase, petroleum compounds can also result in a significant and often abrupt attenuation of ...
 
...petroleum compounds can also result in a significant and often abrupt attenuation of vapors within a few feet of a source area (e.g., heavily contaminated soil or free product on groundwater). ...
 
...ten meters (thirty feet) of clean soil (i.e., TPH <100 mg/kg) is adequate to reduce vapor concentrations to below levels of concern for potential vapor intrusion hazards, regardless ...
 
...concentrations to below levels of concern for potential vapor intrusion hazards, regardless of the mass or concentration of petroleum in underlying soil ...
 
...these separation distances can be used to determine the need to collect actual soil vapor samples at a site. For example, if no contaminated soil is present in the upper thirty ...
 
...soil is present in the upper thirty feet of the vadose zone then potentially significant vapor intrusion hazards can be ruled out without the collection of soil gas samples. If the water ...
 
... on groundwater and contaminated soil is not present in the vadose zone, then potential vapor intrusion hazards can again be ruled out without the collection of soil vapor samples. ...
 
...intrusion hazards can again be ruled out without the collection of soil vapor samples. Shorter vertical separation distances might be appropriate, but should ...
 
...a site-specific basis before a concurrence to negate the need to collect additional soil vapor samples can be granted. This should include borings to characterize subsurface soil types and ...
 
... to characterize subsurface soil types and the collection of a small number of soil vapor samples (e.g., one to three) from an area considered to be representative of overall site conditions. ...
 
...to be representative of overall site conditions. In practice, significant long-term vapor intrusion hazards are unlikely to be posed by dissolved-phase petroleum contaminants in groundwater ...
 
... under any site scenario due to low source strength and rapid biodegradation of vapors in the vadose zone. The collection of soil vapor samples over dissolved-phase plumes ...
 
... in the vadose zone. The collection of soil vapor samples over dissolved-phase plumes can, however, help negate (or identify) the presence of ...
 
... petroleum contamination in the vadose zone. (For dissolved-phase solvent plumes, soil vapor samples are always strongly recommended if action levels for vapor intrusion are approached ...
 
...samples are always strongly recommended if action levels for vapor intrusion are approached or exceeded, regardless of the depth of the plume.) ...
 
...should be evaluated on a site-by-site basis. Significant, lateral migration of petroleum vapors away from source areas is of particular concern at sites covered with pavement or buildings, ...
 
... product on shallow groundwater (i.e., <30ft deep) could lead to the accumulation of vapors under caps and a progressive outward expansion of anaerobic conditions and migration of petroleum ...
 
...and a progressive outward expansion of anaerobic conditions and migration of petroleum vapors over time. Exceptions to the above guidelines are likely to be rare, but could ...
 
...that could allow for significantly greater vertical and lateral migration of petroleum vapors prior to attenuation below target action levels. Other potential exceptions include substantial ...
 
...natural replenishment of oxygen is overwhelmed. Anaerobic conditions and less inhibited vapor migration could also develop under paved areas that overlie deep (i.e., >30ft) widespread, ...
 
...Soil and Groundwater HDOH 2007c). 7.6.2 Soil Vapor Sampling Design 7.6.2.1 Overview A soil vapor sampling ...
 
...Sampling Design 7.6.2.1 Overview A soil vapor sampling strategy depends on site-specific conditions, including soil types and groundwater ...
 
... migration model, and regulatory requirements As discussed below, soil vapor sampling locations are selected based on areas the CSM identifies as having the potential for ...
 
...vertical delineation considerations. Following the selection of sample locations, soil vapor samples can be collected using temporary driven probes or by installing permanent soil vapor ...
 
...samples can be collected using temporary driven probes or by installing permanent soil vapor sampling probes (see Section 7.9). When assessing the source of subsurface vapors, samples ...
 
...sampling probes (see Section 7.9). When assessing the source of subsurface vapors, samples are typically collected within the suspected or known source area, and upgradient, ...
 
...area, and upgradient, downgradient, and cross-gradient of the source area because soil vapor can migrate in a different direction than groundwater flow. When assessing upward, vertical ...
 
...a different direction than groundwater flow. When assessing upward, vertical migration, vapor samples from multiple depths may be useful or even required to evaluate upward attenuation ...
 
...from multiple depths may be useful or even required to evaluate upward attenuation of vapors or highlight the need to identify preferential pathways through otherwise low-permeability ...
 
...buildings. As also discussed in more detail below, the frequency of soil vapor sampling is dependent upon the purpose of the soil vapor investigation. Characterization and ...
 
...sampling is dependent upon the purpose of the soil vapor investigation. Characterization and delineation can require one or two surveys, while remediation ...
 
...does not address safety or hazard mitigation efforts required in the event of explosive vapor accumulation (i.e., methane); however, methane concentrations should be monitored to determine ...
 
...as the Lower Explosive Limit [LEL] for methane). At contaminated sites, additional soil vapor sampling events and possible interim corrective measures should be considered if methane exceeds ...
 
...exceeds 1/10 of the LEL (see Section 9.4). 7.6.2.2 Soil Vapor Sampling Point Locations Figure 7-4: Schematic ...
 
...Locations Figure 7-4: Schematic of Soil Vapor Concentration Profile. VOCs volatilize out of a groundwater plume and diffuse vertically ...
 
...VOCs volatilize out of a groundwater plume and diffuse vertically toward the surface. Vapor phase concentrations are highest at the groundwater-vadose zone interface and decrease ...
 
...highest at the groundwater-vadose zone interface and decrease with decreasing depth. Vapors can accumulate under buildings or paved areas as the ability to diffuse outward and be ...
 
... Point sampling is currently the primary method used to characterize subsurface soil vapors (see Section 7.2). The HEER Office is investigating the use of Decision Unit (DUs) and Multi-Increment ...
 
...objectives (refer to Sections 2 and Section 3). Decision Units designated for vapor intrusion would necessarily be tied to the footprint of existing or future buildings but may ...
 
...footprint. The current HEER Office EHE guidance recommends that soil DUs for potential vapor intrusion hazards be conservatively limited to a default building footprint of 100m2 ...
 
...This is the default area referenced in the models used to develop soil action levels for vapor intrusion. A similar DU area is most likely appropriate for soil vapor, but the number and/or ...
 
...intrusion. A similar DU area is most likely appropriate for soil vapor, but the number and/or volume of individual soil vapor samples or �increment� locations necessary ...
 
...but the number and/or volume of individual soil vapor samples or �increment� locations necessary to adequately represent the DU mean has not been ...
 
...the initial phase of investigation to determine the extent and magnitude of subsurface vapor plumes and to assess exposure pathway completeness and guide selection of future sampling locations. ...
 
... and guide selection of future sampling locations. A relatively small number of soil vapor samples (e.g., three to five) are typically used to identify or negate the presence of VOCs ...
 
...long-term, site conditions then no further action is necessary with respect to potential vapor intrusion hazards (see also Section 7.10.1). The lateral boundaries ...
 
...hazards (see also Section 7.10.1). The lateral boundaries of a vapor plume can be challenging to define once a plume with significant concentration of VOCs has ...
 
...significant concentration of VOCs has been identified in a source area. The shape of a vapor plume might, or more likely might not mimic the shape of the primary source area (i.e., contaminated ...
 
...contaminated soil or groundwater). This is because the outward, lateral migration of vapors away from the source area is strongly influenced by small-scale heterogeneities in the soil ...
 
...preferential pathways that may not be obvious in the field. It is not uncommon for vapor plumes to become detached from the primary source area and be isolated some distance away, ...
 
...of the actual source area location difficult. Locations for soil vapor sampling should be selected based on the objectives of the investigation (see also USEPA 2012d). ...
 
... the investigation (see also USEPA 2012d). If the objective is to identify and map a soil vapor plume, then strategically located sampling points over and around the suspected source area ...
 
...future site use. If the objective of the investigation is to assess potential vapor intrusion impacts at an existing building, then targeted sampling locations at the building, ...
 
... at an existing building, then targeted sampling locations at the building, at the vapor source, and possibly in-between may be appropriate. Grids of passive soil gas samples should ...
 
... gas samples should also be considered (see Section 7.12). The collection of soil vapor samples from immediately beneath building foundations (i.e., below the concrete slab or within ...
 
...or within crawl spaces) is recommended to most directly assess the current potential for vapor intrusion into buildings. Drier soil under slabs can serve to enhance vapor concentrations ...
 
...intrusion into buildings. Drier soil under slabs can serve to enhance vapor concentrations in these soils, in comparison to soils with a higher moisture content (USEPA ...
 
...may also be warranted, since coarse fill in the trenches can serve as a conduit for vapors to the slab as well as to utility penetrations and other potential, preferential pathways ...
 
...for shallow water tables) in order to take into consideration the potential buildup of vapors under existing or future building slabs due to low-oxygen conditions or advective flow. A ...
 
...existing or future building slabs due to low-oxygen conditions or advective flow. A soil vapor sampling strategy that incorporates samples from both immediately beneath the building foundation ...
 
...heterogeneous (USEPA 2012d; Brewer et al. 2014, in prep). A minimum of three vapor points is currently recommended to assess potential vapor intrusion hazards. As a worst-case ...
 
...points is currently recommended to assess potential vapor intrusion hazards. As a worst-case scenario, one or more vapor points should be placed in the ...
 
...intrusion hazards. As a worst-case scenario, one or more vapor points should be placed in the center of the slab, where the concentration of VOCs is predicted ...
 
... contamination beneath the slab (USEPA 2012d; CalEPA 2011; see Section 7.7.2). Vapor points also should be placed in the vicinity of the building where vapor intrusion is considered ...
 
...points also should be placed in the vicinity of the building where vapor intrusion is considered to be most likely, as well as between the center of the building and ...
 
...the building slab, or areas where cracks in the floor could serve as preferential vapor pathways. Sampling points should also be placed in areas of the building suspected to overlie ...
 
...of the building suspected to overlie the highest concentration of a known or suspected vapor plume. The number of probes that can be installed will in part be limited by cost ...
 
...The HEER Office intends to prepare more detailed guidance on the collection of soil vapor samples beneath buildings and for site investigation purposes in general in the future. As ...
 
... Section 7.9.3, recent cheaper and faster options for the collection of subslab soil vapor samples (e.g., pin-type vapor points for slabs) hold promise for the collection of a larger ...
 
...samples (e.g., pin-type vapor points for slabs) hold promise for the collection of a larger number of samples and reduced ...
 
... collection of a larger number of samples and reduced uncertainties regarding potential vapor intrusion hazards. As discussed above, the type of chemicals present in the soil ...
 
...hazards. As discussed above, the type of chemicals present in the soil vapor should also be considered in selecting soil vapor sampling locations. Biodegradation can play ...
 
...should also be considered in selecting soil vapor sampling locations. Biodegradation can play an important role in the subsurface migration of ...
 
...petroleum-related contaminants and can significantly reduce the concentration of VOCs in vapors over short distances. At sites where the chemicals of concern are chlorinated compounds (e.g., ...
 
...of VOCs can persist for significant distances. Elevated concentrations of VOCs in soil vapors can also persist for long periods of time in the vadose zone following active, in situ remediation ...
 
... following active, in situ remediation of contaminated groundwater (�residual vapor plume,� see Table 7-1). The San Diego County Site Assessment and Mitigation (SAM) Manual, among ...
 
...and Mitigation (SAM) Manual, among other references, provides a useful source of soil vapor sampling strategies for a variety of site scenarios (SDC 2011). ...
 
...for a variety of site scenarios (SDC 2011). 7.6.2.3 Soil Vapor Sample Depths and Depth Intervals The depth of soil vapor points depends on the ...
 
...Sample Depths and Depth Intervals The depth of soil vapor points depends on the objectives of the investigation (Figure 7-4). Characterization of known or suspected ...
 
... the subsurface geology and the depth to groundwater. The investigation of potential vapor intrusion hazards will require the placement of sample points within shallow, vapor flow pathways, ...
 
...intrusion hazards will require the placement of sample points within shallow, vapor flow pathways, including utility trenches and fill material immediately beneath slabs (e.g., ...
 
...of soil beneath building slab). Ideally, the lateral and vertical extent of vapor plumes should be delineated out to HDOH Tier 1 soil gas action levels which take into consideration ...
 
...Tier 1 soil gas action levels which take into consideration the potential intrusion of vapors into residential structures (HDOH 2011). Less conservative soil gas action levels may be appropriate ...
 
...need for a land use restriction on the site, however. The collection of soil vapor samples in the fill material immediately beneath a building slab (e.g., first 6 to 12 inches ...
 
...beneath a building slab (e.g., first 6 to 12 inches of soil) is an important part of a vapor intrusion investigation. Relatively permeable, sandy silts are typically used as fill ...
 
...slabs to provide structural stability. This fill material is often more permeable to vapors than the native, clayey soils in Hawai�i and can serve as a preferential pathway for subsurface ...
 
...native, clayey soils in Hawai�i and can serve as a preferential pathway for subsurface vapors via connecting utility trenches or other conduits. Soil vapor samples ...
 
...via connecting utility trenches or other conduits. Soil vapor samples should therefore always be collected in the fill material immediately beneath the slab ...
 
...be collected in the fill material immediately beneath the slab for evaluation of current vapor intrusion hazards, even if deeper samples are also collected. A focus on deeper soil vapor ...
 
...intrusion hazards, even if deeper samples are also collected. A focus on deeper soil vapor sample data can be misleading, since the samples do not take into account upward attenuation ...
 
...soils might be relatively un-impacted, even though the concentrations of VOCs in vapors within the fill material are extremely high. This is a common scenario for dry cleaners, ...
 
...presence of a building slab or other paving also significantly slows, or prevents, soil vapor from diffusing upwards and escaping to the atmosphere. This can result in elevated soil vapor ...
 
...from diffusing upwards and escaping to the atmosphere. This can result in elevated soil vapor VOC concentrations beneath the slab/paving in comparison to adjacent, uncovered areas. Note, ...
 
...floor as an added measure of precaution, in the event that nearby portions of the vapor plume exceed subslab, soil gas action levels even though the measured concentrations of volatile ...
 
... (see also HDOH 2007c). In other cases additional monitoring to verify that adverse, vapor intrusion impacts are unlikely to occur will be needed (see Section 7.10.1). ...
 
...adjacent to buildings, the recommended sampling depth for evaluation of potential vapor intrusion hazards depends in part on the VOCs present. At sites with recalcitrant compounds ...
 
...the VOCs present. At sites with recalcitrant compounds (e.g. chlorinated solvents) soil vapor samples should be collected from no less than five feet below ground surface. Soil vapor samples ...
 
...samples should be collected from no less than five feet below ground surface. Soil vapor samples collected from depths of less than five feet can underestimate the concentrations of ...
 
...of recalcitrant compounds that could accumulate if a building were present. Soil vapor samples should be collected from a minimum depth of ten feet for petroleum-contaminated sites ...
 
...table. This is necessary in order to take into consideration the potential buildup of vapors under existing or future building slabs due to low-oxygen conditions and a reduced potential ...
 
... focus. In some cases it may also be desirable to assess the vertical distribution of vapor-phase contaminants between the source media and the ground surface or the foundation of a building. ...
 
...should also be considered when identifying sampling depths. In general, installation of vapor sampling probes in relatively high permeability horizons is preferred; however, the overall ...
 
...preferred; however, the overall CSM should be taken into account as well. Permanent soil vapor probes should be installed above the maximum-anticipated, seasonally- or tidally-influenced ...
 
... or tidally-influenced elevation of the water table. 7.6.2.4 Soil Vapor Sample Screen Intervals Soil vapor samples are traditionally collected though a ...
 
...Sample Screen Intervals Soil vapor samples are traditionally collected though a temporary or permanent six-inch screen or �implant.� ...
 
...or permanent six-inch screen or �implant.� The optimal depth interval over which a soil vapor sample should be collected has not been well studied, however, nor has the optimal number and ...
 
...has not been well studied, however, nor has the optimal number and volume of soil vapor samples needed to be representative of site conditions. Note that the same is true with respect ...
 
...of one foot. Note that the area of influence associated with a typical, one-liter soil vapor sample is not expected to extend more than a few feet from the well screen (e.g., approximately ...
 
...soil porosity). Additional guidance on the collection of representative soil vapor samples with respect to long-term, vapor intrusion concerns is currently being developed by ...
 
...samples with respect to long-term, vapor intrusion concerns is currently being developed by both the HDOH and other environmental agencies ...
 

7.7 Indoor Air Sample Collection Procedures
... Although counterintuitive, testing of indoor air to identify and evaluate potential vapor intrusion concerns is fraught with potential error and generally discouraged except in cases ...
 
...fraught with potential error and generally discouraged except in cases where subslab soil vapor data indicate a clear threat to indoor air (see HDOH 2011). This is due to the common presence ...
 
...HDOH 2011). This is due to the common presence of the same suite of targeted VOCs in soil vapor in indoor air from sources within or outside of the building (e.g., USEPA 2011e). ...
 
...levels for many common chemicals. Correlation of indoor air data with subsurface, soil vapor data can therefore be difficult if not impossible if the concentration of VOCs identified in ...
 
...background. Although precautionary measures could be taken to mitigate potential vapor intrusion (e.g., sealing of floors, improved ventilation, etc.), as a general rule a home or ...
 
...etc.), as a general rule a home or building should not be flagged for potential vapor intrusion hazards unless this is supported by multiple lines of evidence, including indoor ...
 
...or near the building (i.e., from outdoor air and not the subsurface). Assessments of vapor intrusion should consider the following factors: Indoor air sources (other ...
 
...following factors: Indoor air sources (other than soil vapor); Outdoor air sources (other than soil vapor); Location and characteristics ...
 
... Outdoor air sources (other than soil vapor); Location and characteristics of known or suspected soil vapor source; ...
 
... Location and characteristics of known or suspected soil vapor source; Building ventilation and air exchange rate; Building materials ...
 
...used household products contain some of the same compounds of concern as targeted in vapor intrusion investigations (e.g., TPH and BTEX from cleaners and fuels, PCE from dry-cleaned ...
 
...2010; urban houses. HDOH 2011; indoor action level equal to sum of vapor-phase, TPH aliphatic and aromatic compounds (see Section 7.11). ...
 
... levels. For these reasons, testing of indoor air to evaluate potential vapor intrusion impacts is generally discouraged unless concentrations of targeted chemicals in subslab ...
 
... is generally discouraged unless concentrations of targeted chemicals in subslab soil vapor are more than one-thousand times typical indoor air concentrations for residences and two-thousand ...
 
...HDOH 2011). Indoor air sampling may also be warranted if field screening of potential vapor pathways inside of a building suggest that vapors could be impacting indoor air at levels significantly ...
 
...pathways inside of a building suggest that vapors could be impacting indoor air at levels significantly above background and the pathways are ...
 
...CalEPA 2011, New York State DOH 2006). The evaluation of potential vapor intrusion hazards and decisions regarding the need for remedial actions will instead, in most ...
 
...actions will instead, in most cases, focus on subslab or crawl space data. Shallow soil vapor data or data for samples collected under paved areas can be taken into consideration for sites ...
 
...for sites without existing buildings. Subslab (including sub-basement) soil vapor samples should be collected for buildings with a slab-on-grade construction. For buildings ...
 
... with a slab-on-grade construction. For buildings with a crawl space design, shallow soil vapor samples should be collected adjacent to the building in addition to samples from the crawl ...
 
...in addition to samples from the crawl space. In both cases, it is preferable that soil vapor and/or crawl space samples be collected prior to collection of indoor air samples and ...
 
...the need to collect the latter (see HDOH 2011). If a significant source of potential vapors is present below the building (e.g., petroleum free product on shallow groundwater) then the ...
 
...petroleum free product on shallow groundwater) then the collection of source area soil vapor samples is also recommended (see Sections 7.6.2). Together, subslab and source area data ...
 
...of data should be carried out under the direction and oversight of HDOH. Soil vapor (or crawl space) samples should be collected at the same time in order to assist in the interpretation ...
 
... Section 7.14). Indoor air data should never be used as the only line of evidence for vapor intrusion. Indoor air data should be compared to both risk-based screening levels ...
 
...concentrations. More than one round of sampling is recommended if a significant source of vapors is identified beneath a building (see Section 7.11.3). If representative concentrations ...
 
...within the range of anticipated background concentrations then active measures to address vapor intrusion are not necessary (see Section 7.14.2) , although sealing of cracks and gaps ...
 
...plan. Sources can include, but are not limited to, subsurface contamination (i.e., vapor intrusion), indoor sources (i.e., use/storage of VOC containing chemicals), and outdoor ...
 
... air should be considered in developing a sampling strategy. Common pathways for vapor intrusion from the subsurface are cracks or utility penetrations through the slab or basement ...
 
...earthen floors, and drain pipes. Elevator shafts could also serve as pathways for vapor intrusion, although these structures tend to mimic chimneys by conducting air out of rather ...
 
...tend to mimic chimneys by conducting air out of rather than into buildings, including vapors that might intrude into the bottom area of the shaft. Bathrooms, kitchens and utility ...
 
...kitchens and utility rooms are often the primary entry points for intruding vapors. VOCs can also enter a building through the heating, ventilation, and air conditioning ...
 
...air conditioning system is operating, due to the inflow of fresh air, dilution of vapors from indoor sources and the reduction of subsurface vapor intrusion when the building ...
 
...from indoor sources and the reduction of subsurface vapor intrusion when the building is over pressurized. Indoor air quality will be lowest when ...
 
...in Hawai�i) to outside wind effects that could induce an upward flow of subsurface vapors. Occupants: The presence and activities of building occupants can ...
 
...identify the location, duration, and frequency of indoor air sampling. As with soil vapor sampling strategy, location, duration, and frequency will be influenced by site-specific conditions ...
 

7.8 Soil Vapor or Indoor Air Sample Analysis
... 7.8 SAMPLING APPROACHES AND EQUIPMENT The collection of soil vapor or indoor air samples can be more involved and complex than soil or groundwater sample collection. ...
 
...to the need for special sampling equipment and containers to address the reactivity of vapor-phase chemicals and the need to prevent leaks during sample collection. ...
 
...collection. Based on the type of sampling equipment and containers, soil vapor or indoor air sampling approaches can be grouped into the following categories: (1) whole air ...
 
...reported. Sorbent tube sampling involves drawing a specified volume of soil vapor or indoor air through a sorbent material using a pump or other vacuum source and analyzing ...
 
...by dividing the mass of the compounds collected on the sorbent material by the volume of vapor or air drawn through the sampler. If reanalysis of a sample might be required, then a collection ...
 
... on the sampler is then measured. Flux chambers are traditionally used to measure vapor emission rates from point sources such as waste ponds. Their use in soil vapor investigations ...
 
...emission rates from point sources such as waste ponds. Their use in soil vapor investigations is more limited but in some instances can be beneficial. A comparison ...
 
... inexpensive passive sampling can be used to initially screen a site for shallow vapor plumes and assist in the identification of areas for active soil vapor sampling. For the investigation ...
 
...plumes and assist in the identification of areas for active soil vapor sampling. For the investigation of vapors associated with releases of diesel and other middle ...
 
...sampling. For the investigation of vapors associated with releases of diesel and other middle distillate fuels, a combined used of both ...
 
...recommended during the planning phase for each project requiring the collection of soil vapor or indoor air samples. Equipment that could come in contact with a vapor sample ...
 
...or indoor air samples. Equipment that could come in contact with a vapor sample should be cleaned or decontaminated between samples to avoid cross contamination by ...
 
... Table 7-3 Comparison of Soil Vapor & Indoor Air Sampling Approaches ...
 
... Cannot directly measure vapor concentration ...
 
... Estimation of vapor concentrations possible, multiple samplers can be combined for analysis, ...
 
... Currently costly to install, cannot directly measure vapor concentration ...
 
... Does not measure in-situ concentrations, identification of vapor emission points difficult ...
 
... Table 7-4 Common Soil Vapor Concentration Unit Conversion Factors ...
 
...Lower photo: Single sorbent tube connected to a 60ml syringe for collection of vapor sample (see also Figure 7-27). ...
 
... Figure 7-10 Two Examples of Passive Soil Vapor Sample Collectors. ...
 
...of TCE and PCE Results for Passive Diffusion Sampler and Active Soil Vapor Sample ...
 
...obtained using sorbent tubes and TO-17 analytical methods, although the volume of air or vapor drawn through the tubes is limited by the sorptive capacity of the media used. Individual laboratories ...
 
...whole-air methods (e.g., Air Toxics 2012). Whole air sampling (or other active soil vapor sampling) is recommended to quantify concentrations of vapor-phase chemicals for an exposure ...
 
...sampling) is recommended to quantify concentrations of vapor-phase chemicals for an exposure or risk assessment. Contaminant concentrations can be quantified ...
 
... Table 7-4 presents other common unit conversion factors and HDOH has developed a Vapor Unit Conversion spreadsheet that converts between concentrations and is available for download ...
 
...target compounds conducive to whole air sampling are chemically stable and have a vapor pressure greater than 0.1 torr at 25 ˚ C and 760 millimeters of mercury (one atmosphere). ...
 
...millimeters of mercury (one atmosphere). Effective recovery of chemicals from active soil vapor samples depends on sample humidity, chemical activity of the sample matrix, and the sample ...
 
...a stainless steel container that is placed under a vacuum and then used to collect a soil vapor or air sample. The canister is cleaned internally using electropolishing and chemical deactivation ...
 
...an interior surface that is nearly chemically inert. This minimizes reactions with the vapor sample and maximizes recovery of volatile compounds from the container. Recovery is generally ...
 
...samples (e.g., eight to twenty four-hours). Smaller canisters are typically used for soil vapor samples, for which screening levels are typically several orders of magnitude higher than for ...
 
...are typically several orders of magnitude higher than for indoor air. Collection of vapor samples greater than one-liter can be problematic as well as time consuming at sites with relatively ...
 
...with relatively tight soils. HDOH recommends a minimum sample size of one-liter for soil vapor samples in order to assist in the collection of data that are representative of the site ...
 
...decision making purposes. General procedures when planning a soil vapor investigation using Summa canisters include: Obtain the field ...
 
... Flow controllers (or flow restrictors) are essential equipment for the collection of vapor samples with Summa canisters. The controllers limit the rate at which a sample can be drawn ...
 
... Doing so could potentially strip VOCs from free product or sorbed to soil and bias the vapor sample collected. Older flow controllers tend to be bulky, less reliable and increase the chance ...
 
...(i.e., 10% of canisters) is recommended for standard TO-14 or TO-15 analysis for soil vapor or other applications where very low detection levels are not required. This is appropriate ...
 
...for routine ambient air applications and the collection of high-concentration soil vapor and landfill gas samples where parts-per-million or parts-per-billion reporting levels are ...
 
...Tedlar bags are flexible, plastic bags that can be used for the collection of air or vapor samples with a syringe or a lung box. Tedlar bags can offer an inexpensive, screening tool ...
 
... two layers of Tedlar film sealed at the edges and containing a valve allowing for soil vapor or indoor air sample collection using a syringe or lung box . Tedlar is a trade name for a ...
 
...to 50% or less of their total capacity. As described in Section 7.10.4, soil vapor or indoor air samples are collected in Tedlar bags using a lung box or a syringe equipped ...
 
...Tube Sampling Sorbent tube sampling involves drawing a known volume of soil vapor or air through a sorbent material using a pump or other vacuum source and analyzing the sorbent ...
 
...Concentration is calculated by dividing the mass of a targeted compound by the volume of vapor or air drawn through the sampler. Photographs of sorbent tubes and sorbent tube sampling trains ...
 
...below, sorbent tubes in combination with Summa canisters are recommended for testing of vapors associated with diesel and other middle distillate fuels if a significant (e.g., >10%) ...
 
...to use in the field. A low-flow pump or syringe is used to draw soil vapor or air through the sorbent over a pre-established time period. A maximum flow rate of 200 ml/minute ...
 
...larger volume, indoor or outdoor air samples. If a pump is used then the volume of soil vapor drawn through the tube is calculated by multiplying the average flow rate by the draw time. ...
 
...syringe draw time of no less than 15 seconds, for example, is recommended for a 50ml soil vapor sample. This is the maximum draw volume typically allowed by laboratories for collection of ...
 
...draw volume typically allowed by laboratories for collection of high-concentration soil vapor samples associated with petroleum in order to avoid saturation of the sorbent material in the ...
 
...of volatile compounds at some sites can significantly limit the volume of soil vapor that can be drawn through a sorbent tube without saturation of the sorbent material. Unlike ...
 
...For heavily contaminated, petroleum-release sites in particular, the amount of soil vapor drawn through a sorbent tube might still be limited to volumes as small as 50ml. Smaller volumes ...
 
... Figure 7-9). If sorbent tubes are to be used in a high-concentration, soil vapor environment (e.g., to evaluate TPH in vapors associated with diesel-contaminated soil or groundwater) ...
 
...environment (e.g., to evaluate TPH in vapors associated with diesel-contaminated soil or groundwater) and the volume of vapors to be drawn ...
 
...associated with diesel-contaminated soil or groundwater) and the volume of vapors to be drawn is less than one liter then the concurrent collection of a one-liter or larger ...
 
...7.13). The Summa canister sample should be collected first to help ensure that the vapor point is adequately purged and to improve the representativeness of the sorbent tube sample. ...
 
...into the tubing and soil. The sorbent tube sampling train should then be connected, the vapor point re-opened, and the sample collected. After the sample is drawn, ...
 
... to the laboratory for analysis. The concentration of a targeted chemical in the original vapor is calculated as the mass of the chemical sorbed divided by the volume of vapor drawn through ...
 
...is calculated as the mass of the chemical sorbed divided by the volume of vapor drawn through the sorbent. The storage and holding time for sorbent tubes vary ...
 
...prior to analysis and help reduce analytical time and costs. Note that petroleum vapors are dominated by aliphatic compounds. PIDs primarily target aromatic compounds and are not ...
 
...target aromatic compounds and are not good indicators of total TPH levels in soil vapors without inclusion of a correction factor. This is especially important to remember for aromatic-poor ...
 
...of a correction factor. This is especially important to remember for aromatic-poor vapors from diesel fuel or other middle distillate fuels (refer to HEER Office petroleum vapor study; ...
 
...from diesel fuel or other middle distillate fuels (refer to HEER Office petroleum vapor study; HDOH 2012). PID readings for similar vapor concentrations from gasoline versus diesel ...
 
...study; HDOH 2012). PID readings for similar vapor concentrations from gasoline versus diesel can be significantly lower for the latter. A Flame ...
 
...different lab methods, the difference in the two, reported concentrations of TPH in the vapor samples will give some idea of the proportion of compounds greater than C12. As an alternative, ...
 
...Sampling Passive sampling involves using adsorbent materials to collect vapor phase chemicals without the use of a pump or Summa canister. The vapor is not induced to flow ...
 
...phase chemicals without the use of a pump or Summa canister. The vapor is not induced to flow over the adsorbent; instead the chemicals in the vapor passively contact ...
 
...is not induced to flow over the adsorbent; instead the chemicals in the vapor passively contact the adsorbent and adsorb to it. Both VOCs and SVOCs are captured by the adsorbent ...
 
...sufficiently on the adsorbent and the less-volatile SVOCs may not have sufficient vapor pressure to be detectable. Passive sampling using adsorbent materials is sometimes ...
 
...sampling using adsorbent materials is sometimes used to initially identify targeted, vapor-phase chemicals for site characterizations and vapor intrusion studies. These methods give ...
 
...chemicals for site characterizations and vapor intrusion studies. These methods give a time-integrated measurement and capture temporal variations ...
 
...passive sampling methods that rely on carbon or other sorptive materials to capture vapor-phase VOCs to estimate actual concentration data is hotly debated and not yet widely accepted ...
 
... debated and not yet widely accepted (e.g., USEPA 2009). This is because the volume of vapor that comes into contact with the adsorbent is difficult to determine with a strong degree of ...
 
... difficult to determine with a strong degree of certainty. Calculation of the vapor concentration from passive sampling results is, however, sometimes attempted by estimating ...
 
...passive sampling results is, however, sometimes attempted by estimating the volume of vapor that passes by the buried adsorbent during the burial time period and a vapor diffusion model. ...
 
...that passes by the buried adsorbent during the burial time period and a vapor diffusion model. Another method is to determine an uptake rate for the passive collector. At ...
 
...for the passive collector. At present, comparative studies between actively measured soil vapor concentrations and those estimated from passive sampling are at best within an order of magnitude ...
 
...an order of magnitude (e.g., USEPA 2009). Due to this uncertainty, passive soil vapor data are considered to give qualitative or semi-quantitative vapor concentration results and ...
 
...data are considered to give qualitative or semi-quantitative vapor concentration results and generally are considered a screening tool for soil vapor investigations. ...
 
...concentration results and generally are considered a screening tool for soil vapor investigations. An emerging exception could be the use of water-based passive samples, discussed ...
 
...passive sampling can be beneficial for the initial stages of site characterization or vapor intrusion studies. Advantages of passive sampling include: ...
 
...and to map plumes; Able to detect any contaminant that has an appreciable vapor pressure and can be adsorbed in sufficient quantity to determine relative presence or absence, ...
 
...of passive sampling include: Not useful for generating vertical vapor profiles unless sampling intervals can be effectively isolated; Actual vapor concentrations ...
 
...profiles unless sampling intervals can be effectively isolated; Actual vapor concentrations can only be estimated, limiting use of the method to screening, plume mapping, ...
 
...samplers can also be a problem Passive sampling can be applied to either soil vapor or indoor air. Although the principle is the same in application to these media, the sampling ...
 
... as described in the two sections below. 7.8.3.1 Passive Soil Vapor Sample Collectors Passive soil vapor sample collection involves placing an adsorbent ...
 
...Sample Collectors Passive soil vapor sample collection involves placing an adsorbent into the subsurface for a known exposure period ...
 
... for a known exposure period (e.g., one to two weeks) to allow the adsorption of soil vapor chemicals onto the adsorbent material. Sample collection procedures are described in Section ...
 
...bottom, or in a fine wire mesh or polymeric material, to facilitate contact with the soil vapor but not the soil. Photographs of two vendor-supplied sample collectors are provided in ...
 
... Figure 7-10. Although the results are qualitative, passive soil vapor sampling can provide useful information when investigating subsurface vapor plumes or preferential ...
 
...sampling can provide useful information when investigating subsurface vapor plumes or preferential pathways for vapor intrusion studies. One evolving ...
 
...plumes or preferential pathways for vapor intrusion studies. One evolving approach is to subdivide a site into targeted Decision ...
 
...a site into targeted Decision Units (DU) for screening characterization. Active soil vapor sampling will be targeted for the DU with the highest, relative concentration of VOCs identified ...
 
...of this study, the results of passive diffusion samplers were compared to active soil vapor measurements. These studies showed that: The passive soil vapor sampling ...
 
...measurements. These studies showed that: The passive soil vapor sampling systems detected the same compounds in each sample as the active method, as well ...
 
...method did not detect. This performance characteristic suggests that the passive soil vapor sampling systems may detect VOCs that are at lower concentrations in the subsurface than ...
 
...detect VOCs that are at lower concentrations in the subsurface than the active soil vapor sampling method can detect and/or that the passive samples were able to better capture ...
 
...and/or that the passive samples were able to better capture temporal changes in vapor concentrations due to the longer exposure period. The results also indicated a ...
 
... The results also indicated a general, relative correlation between passive soil vapor sampling results and active method data (e.g., high or low). However, at high contaminant ...
 
...the passive samplers in heavily contaminated areas. Because the passive soil vapor sampling systems and the active method use different techniques to collect soil vapor samples, ...
 
...sampling systems and the active method use different techniques to collect soil vapor samples, it is not expected that the two methods will provide the same response or that ...
 
... material inside – the vial is capped with a gas-permeable membrane, which allows vapors to enter the vial but excludes any particulate matter in the air As discussed ...
 
... 7.8.3.3 Emerging Technologies The field of soil vapor and indoor air passive sampling is rapidly developing. There are a number of technologies that ...
 
...sampler (PDS) has been developed by the USEPA Office of Research and Development for soil vapor characterization (Paul 2009). This sampler uses water as the media into which contaminants ...
 
...including more polar compounds. More reliable estimates of VOC concentrations in soil vapor may be possible. The PDS is constructed using a 40 ml VOA vial filled with de-ionized ...
 
...a 40 ml VOA vial filled with de-ionized water and with the Teflon septa replaced with a vapor-permeable membrane. The PDS is inserted into a custom-made messenger (hollowed-out plastic ...
 
...two-inch diameter, monitoring wells with a screened interval placed at the desired soil vapor depth interval. Figure 7-12 shows a schematic of the PDS and a photo of the sampler ...
 
...into the water-filled PDS until the water reaches equilibrium with the surrounding soil vapor. The PDS is recovered from the well after an appropriate equilibration period, typically ...
 
... to estimate the average, equilibrium concentration of the VOC in the surrounding soil vapor. Several comparative field studies of this technology in application to petroleum ...
 
...Table 7-5 lists the results of one study wherein PDS sampler results were converted to vapor concentrations using Henry’s Law and then compared to a collocated active (e.g., Summa) soil ...
 
...using Henry’s Law and then compared to a collocated active (e.g., Summa) soil vapor measurement. In this study, the PDS estimated concentrations of vapor-phase VOCs were consistently ...
 
...measurement. In this study, the PDS estimated concentrations of vapor-phase VOCs were consistently higher than those reported for the active samples for both PCE ...
 
...either: 1) A consistent error in conversion of dissolved-phase VOCs to equivalent vapor-phase VOCs and/or 2) The existence of subsurface spatial and/or temporal vapor “hot spots” ...
 
...VOCs and/or 2) The existence of subsurface spatial and/or temporal vapor “hot spots” that were captured by the PDS sampler due to their longer exposure time but missed ...
 
... to adjacent areas or for estimation of time-averaged VOC concentrations for use in vapor intrusion studies. Whether or not PDS samples can indeed be used to obtain a more representative ...
 
...can indeed be used to obtain a more representative picture of long-term subsurface soil vapor conditions at a site is still under investigation. 7.8.4 Flux Chamber ...
 
... ITRC 2007; Figure 7-13). Flux chambers were originally designed to estimate vapor emissions from open waste pits in terms of mass per unit area per unit time (e.g., mg/m2-hour). ...
 
...eliminates some of the assumptions required when using other types of subsurface data in vapor intrusion models. Unlike soil vapor or indoor air samples, flux chamber data can be used to ...
 
...intrusion models. Unlike soil vapor or indoor air samples, flux chamber data can be used to definitively identify and document ...
 
...flux chamber data can be used to definitively identify and document the emission of vapors from subsurface sources to the atmosphere or to the interior of buildings. The method has ...
 
...emissions from natural soils. HDOH considers its quantitative value for soil vapor and vapor intrusion assessments to be limited, and HDOH should be contacted prior to the use ...
 
...and vapor intrusion assessments to be limited, and HDOH should be contacted prior to the use of flux ...
 
...and HDOH should be contacted prior to the use of flux chambers in site investigations or vapor intrusion studies. Flux chambers are primarily useful as a qualitative tool to locate surface ...
 
...part to the small area tested and difficulty in capturing the heterogeneity of subsurface vapors, as well as short term temporal variations in downward versus upward vapor flux (e.g., due ...
 
...as well as short term temporal variations in downward versus upward vapor flux (e.g., due to changes in barometric pressure). Use in open areas also does not mimic vapor ...
 
...flux (e.g., due to changes in barometric pressure). Use in open areas also does not mimic vapor flux into buildings. The presence of small-scale, preferential pathways in soils (e.g., desiccation ...
 
...floor surfaces such as single family residences, because the primary entry points of soil vapor into the structure (cracks, holes, sumps, etc.) are often concealed by floor coverings, ...
 
...analyzer or on-site GC can be used to attempt to identify the primary locations of vapor intrusion. Regardless of the method used, enough chamber measurements should be ...
 

7.9 Gas Phase Sample Evaluation
... ' 7.9 ACTIVE SOIL VAPOR PROBE INSTALLATION ...
 
... Figure 7-14: Typical Temporary Soil Vapor Probe Typical temporary soil vapor probe, designed to be driven by a direct-push drill ...
 
...Probe Typical temporary soil vapor probe, designed to be driven by a direct-push drill rig. The probe tip components ...
 
... Figure 7-15: Installing a Temporary Soil Vapor Probe Using a Direct-Push Drill Rig After the probe is driven to the desired sampling ...
 
...of the boring, and creating a cavity in the soil that provides access to the soil vapor at the desired depth for sampling. The photograph on the right shows a temporary soil ...
 
...desired depth for sampling. The photograph on the right shows a temporary soil vapor sampling probe in place. ...
 
... Figure 7-16 Vapor Point Completions Left: Surface completion of flush-mounted well with valve installed. ...
 
... Figure 7-17 Typical Nested Permanent Soil Vapor Sampling Probes ...
 
... Figure 7-18 Installation of a Permanent Soil Vapor ProbeUpper left photo: Hand-augering the borehole. Upper right photo: Preparation of ...
 
...left photo: Hand-augering the borehole. Upper right photo: Preparation of soil vapor sampling point. Bottom left photo: Hydrating the bentonite seal. Tape used to measure ...
 
... of borehole, sand pack, and bentonite. Bottom right photo: Purging the completed vapor probe. Surface completion is a 9-inch length of 3-inch diameter Schedule 40 PVC pipe ...
 
... Figure 7-19 Schematic of Typical Sub-Slab Soil Vapor Sampling Probe (see also Figure 7-20 & 7-21). ...
 
... Figure 7-20 Sub-Slab Soil Vapor Sampling Probes Upper left photo: Drilling hole with hand-held rotary hammer drill. ...
 
...bentonite seal. Bottom Left: Temporary probe completion. Bottom Middle and Right: Vapor probe with Swagelok termination fitted to hole (note larger diameter hole near surface), ...
 
... Figure 7-21 Sub-Slab Soil Vapor Sampling Probes Left: Example dual Swagelock setup for connection of vapor point to ...
 
...Sampling Probes Left: Example dual Swagelock setup for connection of vapor point to collection device (see Figure 7-17 and Figure 7-20) Right: Tubing ...
 
...device (see Figure 7-17 and Figure 7-20) Right: Tubing from vapor point and collection device connected with a union joint. ...
 
... Figure 7-22: Installation of a Vapor Pin™ with a silicon sleeve directly into slab for collection of subslab vapor ...
 
...Pin™ with a silicon sleeve directly into slab for collection of subslab vapor samples (screw-on protective cap shown in photo to right). Sample collection tubing ...
 
... the base. The purpose of soil vapor probes is to provide access to subsurface soil vapor so that an active sample can be collected. ...
 
...probes is to provide access to subsurface soil vapor so that an active sample can be collected. Soil vapor probes must be properly installed ...
 
...so that an active sample can be collected. Soil vapor probes must be properly installed to collect representative soil vapor samples and to minimize ...
 
...probes must be properly installed to collect representative soil vapor samples and to minimize the effects of changes in barometric pressure, temperature, or breakthrough ...
 
...for development of conceptual site models, including an understanding subsurface vapor transport pathways and mechanisms, and for selecting vapor probe depths. ...
 
...transport pathways and mechanisms, and for selecting vapor probe depths. Permanent probes typically consist of small, inert tubing (e.g. 1/4-inch ...
 
...a larger vertical interval ((API 2005). This is especially important for subslab soil vapor samples, where the average concentration of VOCs within one-foot of the slab around preferential ...
 
...Figures 7-16 and Figure 7-17 present several examples of flush-mounted soil vapor points and a schematic diagram of vapor probe point designs. Approximately ...
 
...points and a schematic diagram of vapor probe point designs. Approximately 1 foot of dry granular bentonite should be placed ...
 
...is always installed first. Figure 7-18 depicts the installation of a permanent vapor probe using a hand auger. Permanent probes should be finished to preclude infiltration of water ...
 
...Surface completions of permanent probes typically include a fitting that allows for soil vapor sample collection and a gas tight valve at the surface when the probe is not in use. Flush ...
 
... with 6 to 12 inches of tubing above the surface with a 2-way valve to seal it. Deeper vapor points can also be set beneath buildings slabs to investigate source-area vapor concentrations ...
 
...points can also be set beneath buildings slabs to investigate source-area vapor concentrations (see Section 7.6.2.3). Reviewing as-built plans and screening proposed vapor ...
 
...concentrations (see Section 7.6.2.3). Reviewing as-built plans and screening proposed vapor points using GPR or similar methods to check for rebar and other potential obstacles to drilling ...
 
...contamination; and 4) in the vicinity of cracks and gaps in the building slab where vapor intrusion is considered to be most likely (see also USEPA 2012d, CalEPA 2011). Examples ...
 
...the building slab, or areas where cracks in the floor could serve as preferential vapor pathways. Traditional subslab probes are installed by drilling a hole of appropriate ...
 
...the threaded plug. Figure 7-20 & Figure 7-21 depict completions for subslab vapor points. Alternative approaches that can reduce the time, effort and cost of collecting ...
 
...approaches that can reduce the time, effort and cost of collecting subslab soil vapor samples are being developed. One example includes the “Vapor PinTM,” which is installed directly ...
 
...samples are being developed. One example includes the “Vapor PinTM,” which is installed directly into the floor slab and does not require the installation ...
 
...If used, then an equilibrium time of at least two hours following installation of the vapor point (including vapor pins) is recommended. 7.9.4 Soil Vapor Probe ...
 
...point (including vapor pins) is recommended. 7.9.4 Soil Vapor Probe Tubing ...
 
... pins) is recommended. 7.9.4 Soil Vapor Probe Tubing Inert, rigid-walled tubing, such as Teflon, nylon (e.g. Nylaflow), ...
 
...nylon (e.g. Nylaflow), or stainless steel should be used as the primary tubing for soil vapor sampling probes (Ouellette 2004, SDC 2011, USEPA 2009). Tests using these materials ...
 
...from ambient air or other sources. Avoid leaving tubing near open sources of vapors (e.g., fuel cans, cleaners, etc.) or near auto exhaust.. 7.9.5 ...
 
...fuel cans, cleaners, etc.) or near auto exhaust.. 7.9.5 Soil Vapor Probe Abandonment When soil vapor probes are no longer needed they should be properly ...
 
...Probe Abandonment When soil vapor probes are no longer needed they should be properly abandoned. Abandonment procedures for temporary ...
 

7.10 Documentation of Soil Vapor or Indoor Air Sampling
... ' 7.10 ACTIVE SOIL VAPOR SAMPLING PROCEDURES Table 7-6 Sand ...
 
... Figure 7-23: Soil Vapor Probe Purging Devices Upper photo: Disposable syringe with 3-way Luer valve (see also ...
 
...Tedlar bag. Vacuum is drawn on sealed lung box, causing the Tedlar bag to pull vapor from the collection point and fill. ...
 
...Summa canister sampling trains. Upper schematic: Diagram of Summa canister soil vapor sampling apparatus. Lower photo: Teflon tubing connected to flow controller with swage ...
 
... Figure 7-27: Example Soil Vapor Sample Collection Setups Upper photo: Battery powered sampling pump draws soil vapor ...
 
...Sample Collection Setups Upper photo: Battery powered sampling pump draws soil vapor through the Teflon tubing from the temporary soil vapor probe tip to the sample sorbent ...
 
...through the Teflon tubing from the temporary soil vapor probe tip to the sample sorbent tube. A restrictor device reduces the pump flow to ...
 
...type of sorbent tube media. Middle schematic and photo: TO-17 sorbent tube soil vapor sampling apparatus. Vapor point tubing connected to sorbent tube inlet with a union ...
 
...sampling apparatus. Vapor point tubing connected to sorbent tube inlet with a union and swage lock; pump or syringe ...
 
...(latter shown in photo). Lower left photo: Summa canister used to collect soil vapor from a permanent soil vapor point. The blue-bodied flow controller is laboratory-calibrated ...
 
...from a permanent soil vapor point. The blue-bodied flow controller is laboratory-calibrated to restrict sample ...
 
...Figure 7-28). Small Summas used to collect samples; large Summa used to purge vapor point. Dual vacuum gauges in each setup used to monitor Summa vacuum and vacuum at ...
 
... Source of leak at sampling train vs vapor point or annular seal cannot be determined (although successful shut-in ...
 
... Figure 7-28: Soil Vapor Sampling Trains Arranged for Shut-in Test (see also Figure 7-27) ...
 
..."Water Dam" Sealed to Floor with Inert Putty for Leak Testing Slab-mounted Vapor Point. After Cox-Colvin 2013, b. The water level is filled to a level ...
 
... 2013, b. The water level is filled to a level above the tubing connection to the vapor point and monitored during a vacuum test prior to and during sample collection. ...
 
... Figure 7-30: Shroud Over Vapor Probe Surface Completion. Upper Photo: System consists of shroud (blue bucket), industrial-grade ...
 
...set into a ring of Play-Doh on concrete base to provide a tighter seal around vapor point. Large Summa used to purge well point; smaller Summa used to collect sample (see ...
 
...into shroud and used as tracer to identify leaks in both sampling train and vapor probe annular seal. Upper left photo: Five-gallon bucket helium shroud placed over ...
 
... The descriptions of active soil vapor sampling procedures in the following sections are general in nature and reflect commonly accepted ...
 
...more appropriate depending on sampling objectives 7.10.1 Soil Vapor Sample Timing and Frequency Like sample location and depth, the timing and frequency ...
 
...investigation is to develop a CSM that reflects the representative, average subsurface vapor concentrations and vapor intrusion conditions over time and during normal building operation ...
 
...concentrations and vapor intrusion conditions over time and during normal building operation over a period of many years ...
 
...of assumed, long-term, average site conditions. The collection of soil vapor samples from both the fill material immediately under the building slab and the suspected or ...
 
...floor as an added measure of precaution, in the event that nearby portions of the vapor plume exceed subslab, soil gas action levels even though VOCs meet action levels in subslab ...
 
...the EHE overview, site-specific considerations regarding the timing and frequency of soil vapor sample collection include building HVAC system operation, seasonal weather variations and associated ...
 
...are recommended if the conceptual model identifies the VOC concentrations in source area vapors well above shallow soil gas action levels and the potential for significant, temporal fluctuations ...
 
...soil gas action levels and the potential for significant, temporal fluctuations in soil vapor concentrations and or the potential for advective flow of vapors into overlying buildings. ...
 
...concentrations and or the potential for advective flow of vapors into overlying buildings. Recommendations include: Collection and comparison of ...
 
...include: Collection and comparison of subslab soil vapor samples (or crawl space samples) during periods of the year when air conditioning is and ...
 
...summer versus winter months); Collection of deep and subslab soil vapor samples (or crawl space samples) during both the wet and dry season for sites where a significant ...
 
...vary dramatically over the year. The collection of seasonal soil vapor samples should be considered at sites where a substantial smear zone that could be exposed ...
 
...falling water tables is known or suspected to be present. The collection of subslab soil vapor samples during periods of both falling and rising water table may be necessary on a site-specific ...
 
...on a site-specific basis to evaluate the effects of tidal pumping on subslab soil vapor concentrations at high-risk, coastal sites with significant free product on shallow groundwater. ...
 
... At sites near the coast, the tides can affect groundwater levels, soil vapor samples should be collected at the same point in the tidal cycle in order to obtain data ...
 
...water tables) may also be necessarily, especially if significant concentrations of vapor-phase contaminants have been identified in deeper, soil vapor samples. A single ...
 
...contaminants have been identified in deeper, soil vapor samples. A single round of soil vapor sample collection will generally be acceptable ...
 
...samples. A single round of soil vapor sample collection will generally be acceptable for sites that meet the following conditions ...
 
...source is present in the vadose zone. At least two rounds of soil vapor sampling, one during the �dry� season and one during the �wet� season, are recommended prior ...
 
...season and one during the �wet� season, are recommended prior to negation of potential vapor intrusion hazards for sites that meet the following conditions: 1) Sites with widespread, ...
 
...above-noted conditions or 2) Confirmation of remedial actions at sites where potential vapor intrusion hazards have been documented in the past (e.g., concentrations of VOCs in ...
 
...hazards have been documented in the past (e.g., concentrations of VOCs in subslab soil vapor greater than action levels and/or impacts to indoor air above action levels or expected background ...
 
...impacts to indoor air above action levels or expected background identified and tied to vapor intrusion). If more than one round of soil vapor samples are collected, the field ...
 
...intrusion). If more than one round of soil vapor samples are collected, the field procedures (e.g., purge volume), sample containers, and analytical ...
 
... Short-term (minutes or days), temporal variation of concentrations in soil vapors due to changes in temperature, barometric pressure, and wind speed due to passing ...
 
...or more (USEPA 2007e). Infiltration from rainfall can potentially impact soil vapor concentrations by displacing soil vapor, dissolving volatile organic compounds, and by creating ...
 
...concentrations by displacing soil vapor, dissolving volatile organic compounds, and by creating a �cap� above the soil vapor. In practice, ...
 
...dissolving volatile organic compounds, and by creating a �cap� above the soil vapor. In practice, infiltration from brief, large storms only penetrates into the soil on the order ...
 
... from brief, large storms only penetrates into the soil on the order of inches. Soil vapor samples collected at depths greater than 3 feet bgs are therefore unlikely to be significantly ...
 
...depths greater than 3 feet bgs are therefore unlikely to be significantly affected. Soil vapor samples collected closer to the surface (less than 3 feet) without surface cover may be affected. ...
 
... a sample or drops of moisture are evident in the sampling train or sample, a soil vapor sample should not be collected (e.g., vacuum greater than seven inches Hg or 100 inches of ...
 
...short circuiting to the surface, imposition of a high vacuum on the soil could cause non vapor-phase VOCs to be stripped in free product, sorbed to soil or dissolved in soil moisture and ...
 
...in free product, sorbed to soil or dissolved in soil moisture and bias the resulting vapor sample. Measurement of soil moisture can also be useful if shallow sampling is performed during ...
 
...rainfall (e.g., greater than 1 inch; SDC 2011 7.10.2 Soil Vapor Probe Equilibration Subsurface soil vapor conditions are disturbed during installation ...
 
...Probe Equilibration Subsurface soil vapor conditions are disturbed during installation of soil vapor sampling probes. In general, temporary ...
 
...conditions are disturbed during installation of soil vapor sampling probes. In general, temporary probes advanced with manual or direct push ...
 
...advanced with manual or direct push methods result in the least disturbance to soil vapor conditions and can be purged and sampled relatively soon after installation. Permanent probes ...
 
...on the investigation objectives and the data quality requirements. For example, if a soil vapor survey is conducted using temporary points to map the extent of a vapor plume, and the ...
 
...survey is conducted using temporary points to map the extent of a vapor plume, and the sample data are not intended for use in risk assessment or site closure decisions, ...
 
...would be acceptable. To obtain quality data for decision making, permanent soil vapor probes should be allowed to equilibrate for at least 24 (direct push) to 48 (augers) hours ...
 
...test, leak test and soil gas sampling for at least two hours following completion of vapor probe installation; For soil gas wells installed with hollow stem or hand auger ...
 
...test, leak test and soil gas sampling for at least 48 hours following completion of vapor probe installation. For subslab soil gas probes installed in soil beneath the ...
 
...test, leak test and soil gas sampling for at least two hours following completion of vapor probe installation For vapor collection pins installed directly into the slab, ...
 
...probe installation For vapor collection pins installed directly into the slab, do not conduct the purge volume test, ...
 
...leak test and soil gas sampling for at least twenty minutes following completion of vapor probe installation (e.g., see Cox-Colvin 2013); Cap the vapor pins ...
 
...probe installation (e.g., see Cox-Colvin 2013); Cap the vapor pins immediately after they are installed in order to minimize the potential for cross slab ...
 
...(e.g., air conditioned buildings under positive pressure). 7.10.3 Soil Vapor Probe Purging Vapor probes should be purged of stagnant or ambient air in tubing ...
 
...Probe Purging Vapor probes should be purged of stagnant or ambient air in tubing and other equipment and filled ...
 
...be purged of stagnant or ambient air in tubing and other equipment and filled with soil vapor prior to collection of a sample. The volume of air space in sand packs installed with the vapor ...
 
...prior to collection of a sample. The volume of air space in sand packs installed with the vapor point should be included in purging if less than 24 hours has lapsed since installation of ...
 
... for common borehole and tubing sizes. Opinions vary on the optimum volume of vapor to be purged from a vapor point prior to the collection of a sample. Several published studies ...
 
...to be purged from a vapor point prior to the collection of a sample. Several published studies for relatively coarse ...
 
...be in equilibrium with the surrounding native soils. The volume purged between different vapor points set at similar depths at a site should be approximately the same. ...
 
...depths at a site should be approximately the same. For in-slab, pin-type vapor points (e.g., Vapor PinsTM), minimal purging is required due to the small volume of air associated ...
 
...points (e.g., Vapor PinsTM), minimal purging is required due to the small volume of air associated with the pin ...
 
...a well point can have several drawbacks (SDC 2011). The larger the quantity of soil vapor drawn, the greater the uncertainty in the location of the collected sample. Large purge volumes ...
 
...five minute draw time for a one-liter canister. When purging a well point or collecting a vapor sample with a syringe, the flow rate is maintained by drawing the plunger back at a steady ...
 
... can result in a biased sample. Imposition of a high vacuum on the soil could cause non vapor-phase VOCs in free product, sorbed to soil or dissolved in soil moisture to be stripped and ...
 
...sorbed to soil or dissolved in soil moisture to be stripped and bias the resulting vapor sample. As flow rates and vacuum levels increase, the risk of leakage in the sampling probes ...
 
...problems for the laboratory, but also compromises the integrity of the sample data since vapor-phase compounds could partition into the water during storage and shipment of the sample. If ...
 
...Summa canister measures the vacuum in the canister, not the vacuum applied to the soil vapor probe. A qualitative method to quickly determine if the permeability of the soil ...
 
...reduction in the flow rate does not reduce the sampling vacuum, then an alternative vapor point would be installed with a large sand pack emplaced in the zone of interest (SDC 2011). ...
 
...three liters, which implies the use of approximately ten liters of sand for the pack. A vapor point is installed in the pack and completed at the surface. The top of the sand pack should ...
 
...be capped with bentonite to prevent break though to ambient air. A vapor sample should only be collected after the sand pack has reached equilibrium with the surrounding, ...
 
...in the sand pack. Sample size should be limited to one liter. The vacuum within the vapor probe should be measured during sampling to ensure that seven inches Hg is not exceeded during ...
 
...Hg is not exceeded during the purging and sample collection 7.10.4 Soil Vapor Sampling Trains A variety of sampling systems can be used to collect representative ...
 
... A variety of sampling systems can be used to collect representative soil vapor samples. Individual laboratories typically provide guidance on recommended designs of sampling ...
 
...be filled using a lung box. A lung box is an air-tight container with ports for the soil vapor probe tubing and separate tubing to a pump. The Tedlar bag is connected to the vapor probe ...
 
...probe tubing and separate tubing to a pump. The Tedlar bag is connected to the vapor probe tubing and then placed inside the lung box. A pump is used to evacuate the lung box, ...
 
...is used to evacuate the lung box, which causes the Tedlar bag to expand, drawing in soil vapor (Figure 7-25). A schematic diagram and photograph of a soil vapor sampling apparatus ...
 
...(Figure 7-25). A schematic diagram and photograph of a soil vapor sampling apparatus for collecting samples in Summa canisters is depicted in Figure 7-26 ...
 
...Summa canisters is depicted in Figure 7-26 and includes the following major elements: the vapor probe tubing, a vacuum gauge, sample tubing (inert tubing such as Teflon, nylon, or stainless-steel), ...
 
... Figure 7-27 shows several typical sampling apparatus in which soil vapor samples are being collected with a sorbent tube and Summa canisters. In the bottom, ...
 
...of the sampling train (see Section 7.10.5.1). 7.10.5 Soil Vapor Probe Leak Testing Leak tests are an important part of quality assurance and are ...
 
...tests are an important part of quality assurance and are strongly recommended for each vapor sample. The nature of leaks tests carried out as part of a site investigation should be clearly ...
 
...and discussed in the resulting report. Leaks in sampling train fittings or leaks at the vapor point annulus can result in dilution of the soil vapor samples with ambient air and under reporting ...
 
...point annulus can result in dilution of the soil vapor samples with ambient air and under reporting of actual contaminant concentrations. Most leaks ...
 
... Most leaks occur in the sampling train, rather than in the annulus around the vapor probe surface seal. Excessive vacuum conditions resulting from low porosity soils ...
 
...train in the field, 2) A �water dam� test for field testing of the integrity of the vapor point when installed into a slab or other relatively impermeable surface and 3) A tracer test ...
 
...and 3) A tracer test to determine the presence or absence of gas introduced around the vapor point and/or the sampling train in the sample that is collected. Performance of a shut-in test ...
 
...a shut-in test of the sampling train is recommended prior to the collection of all soil vapor samples. As described below, this allows the tightness of the sampling train to be quickly ...
 
...in the field. A water dam test, as described below, or equivalent test is recommended for vapor points installed in intact slabs prior to sample collection. This allows the tightness of the ...
 
...prior to sample collection. This allows the tightness of the annular space around the vapor point to be quickly tested in the field. Tracer tests are recommended to test the ...
 
...tested in the field. Tracer tests are recommended to test the tightness of vapor points installed in soil, cracked slabs, pavement or other cases where a bentonite seal is ...
 
...high public profile sites where where lab data are desired to confirm sampling chain and vapor point tightness. As described below, two tracer gas methods are recommended: (1) Application ...
 
...two tracer gas methods are recommended: (1) Application of a leak check compound to the vapor probe surface seal or (2) Application a tracer gas to the entire sampling apparatus. Table ...
 
...gas. Use of one of the two tracer methods described above is recommended for vapor points with connections that cannot be included in a shut-in test and for all samples collected ...
 
...initial sample drawn from the well point can be used to help verify the integrity of the vapor point prior to submittal of samples to a laboratory (e.g., collection of an initial sample ...
 
... A simple shut-in test will be adequate for the routine collection of soil vapor samples when the depth of the probe is greater than 10 feet and all connections in ...
 
... in the sampling train can be included in the test. Testing the tightness of the vapor point connection with the ground surface is less critical in these cases given the depth to ...
 
... of remaining samples. The use of a full shroud over both the sampling train and vapor point could, however, be recommended or even required for sites with a high public profile, ...
 
... Note that simple release of tracer gas around sampling train connections and the vapor probe seal at the ground surface in the absence of a shroud is not recommended, since the concentration ...
 
...types of helium field detectors due to very high concentrations of C5-C12 hydrocarbons in vapors in soil gas. This can be assessed prior to purging and sample collection by connecting ...
 
...prior to purging and sample collection by connecting the helium detector directly to the vapor point and evaluating the response. Ultra high-purity helium (e.g., Grade 5) is recommended ...
 
...in cheaper, �party-grade� helium High levels of light-end, petroleum vapors have also been reported to cause false, elevated readings of methane in vapor samples using ...
 
...have also been reported to cause false, elevated readings of methane in vapor samples using a standard, landfill gas analyzer. The use of a carbon trap is recommended when ...
 
... A sampling train shut-in test is recommended prior to the collection of all soil vapor samples. The shut-in test is performed by isolating the sampling train from the vapor sampling ...
 
...samples. The shut-in test is performed by isolating the sampling train from the vapor sampling point and applying a vacuum to the sampling train. The applied vacuum should hold ...
 
...trains arranged for a shut-in test. The system consists of a gas tight 2-way valve at the vapor probe termination, a 3-way valve to connect the vapor probe to the sample container, ...
 
... probe termination, a 3-way valve to connect the vapor probe to the sample container, and a vacuum gauge and syringe with shut-off valve. The 2-way ...
 
... should be rechecked and the shut-in test repeated. 7.10.5.2 Water Dam Vapor Point Test A �water dam� offers a simple and inexpensive method to test for leaks ...
 
... A �water dam� offers a simple and inexpensive method to test for leaks around vapor points installed into a slab or other relatively impermeable surface (e.g., see Cox-Colvin ...
 
...installation, water is poured directly into the depression cut into the floor around the vapor point (see Figure 7-22). For a stick-up installation, a coupling can be sealed to ...
 
...or the annular space of a flush-mount depression to immerse the tubing connection to the vapor point. Note that water soluble clays such as Play-Doh might absorb too much water to be ...
 
...for tests that last more than one hour. Assemble the sample train and connect it to the vapor point. Perform a shut-in test to verify that the sample train can hold a vacuum for one to ...
 
...five minutes with no more than 0.5 in Hg loss of vacuum (see previous section). Purge the vapor point and monitor the water level in the dam. The water level might drop slightly due to absorption ...
 
... however. If this occurs then remove the distilled water and reposition or reseal the vapor point to address the leak. 7.10.5.3 Tracer Method 1 � Application of Tracer ...
 
...apparatus (Method 2), including sample container, all tubing and connections, and the vapor probe surface completion in a shroud, which is filled with tracer gas. ...
 
...shroud is the ability to document the lack of a leak in both the sampling train and the vapor point seal by testing for helium in the sample analyzed by the laboratory. Combination with ...
 
...collected and analyzed then it can also be concluded that the leak occurred around the vapor point annular seal. A disadvantage of full-system shrouds is the volume of helium required, ...
 
...concentrations of VOCs are within ten percent of the actual concentration of VOCs at the vapor point in the field at the time the sample was collected. If a field meter is not used to monitor ...
 
...leak. Fully document and discuss any detections of leak check compound in the soil vapor investigation report. 7.10.5.6 Selection of Leak Check Compound ...
 
...does not require the use of a shroud, as it can be applied to a towel placed around the vapor probe, although it can also be used with a shroud by placing the towel inside the shroud. Isopropanol ...
 
...and may be particularly useful for testing leaks associated with the anular space of the vapor point (see Figure 7-35). A further advantage of isopropanol is that it can be detected using ...
 
...Quantification of leaks is likewise difficult, since the original concentration of vapor-phase isopropanol under the shroud can at best be estimated based on its vapor pressure. Isopropanol ...
 
...isopropanol under the shroud can at best be estimated based on its vapor pressure. Isopropanol is also sometimes used as an additive in gasoline. This could again lead ...
 
... adequate mixing under a shroud if it is used as a tracer for leak detection around vapor points. Difluoroethane (in office duster cans) is readily available and simpler ...
 
...a comparison of these leak check compounds. 7.10.6 Soil Vapor Sample Collection Steps The following general steps should be followed when collecting ...
 
...Steps The following general steps should be followed when collecting soil vapor samples: Allow the sampling probe to equilibrate with the subsurface ...
 
... Purge the sampling apparatus as discussed in 7.10.3. Collect the soil vapor sample into the appropriate sample container. Disassemble the sampling apparatus ...
 
...apparatus making sure to close the valves on the sample container and the soil vapor sampling probe. Transport the sample to the analytical laboratory ...
 
... following standard chain-of-custody procedures. 7.10.7 Soil Vapor Sample Notes and Logs Good field notes and logs are important components of soil ...
 
...Notes and Logs Good field notes and logs are important components of soil vapor investigations. Take clear notes in the field. State the goals of each planned activity at ...
 
...methods and devices; Purging and sampling rates; PID readings; Soil vapor probe system volumes; Volume of soil vapor extracted prior to sampling; ...
 
...probe system volumes; Volume of soil vapor extracted prior to sampling; Sample volume; If canisters are used, vacuum ...
 

9.1 Pesticide Contamination at Former Agricultural Facilities and Sites
... 2012b). An evaluation of potential contaminant mobility in terms of vapor-phase or dissolved-phase (i.e., leachate) mobility in soil is important (refer to Appendix ...
 
...as "volatile" in the HDOH EHE guidance are considered to be highly mobile in the vapor phase [Henry's number >0.00001 atmosphere cubic meters per mole (m3/mol)] and molecular ...
 
...be a contaminant of concern in former pesticide mixing, storage or disposal areas. Soil vapor data collection is strongly recommended when investigating for these areas. ...
 
...(chronic direct exposure), Ametryn and atrazine (leaching), Petroleum (vapor intrusion, gross contamination, leaching), Lead (chronic direct exposure), ...
 

9.3 Petroleum Contaminated Sites
...ranges. As discussed below, reference to these ranges is less useful for air and soil vapor data. "Gasoline-range" TPH is defined as a mixture of petroleum compounds characterized ...
 
...alkenes, and cycloalkanes of the same carbon range (see also NEIWPCC 2003). Vapors from these fuels tend to be dominated by lighter-range, more volatile, C5-C8 aliphatics (HDOH ...
 
...These fuels also contain a small but important amount of lighter, aliphatic compounds. Vapors from the fuels can somewhat counterintuitively be dominated by these "gasoline range," C5-C12, ...
 
...it is important that these compounds be included in the analysis of TPH in air and soil vapor samples associated with releases of middle distillate fuels. Dissolved-phase, middle-distillate ...
 
...petroleum compounds (Chaplin 2002). This necessitates the collection of soil vapor samples at sites contaminated by heavier fuels, as well as gasolines and middle distillates. ...
 
...etc.) Soil Vapor TPH, BTEX, naphthalene and MTBE plus other ...
 
...and 2-) Soil Vapor TPH, BTEX, naphthalene, and methane ...
 
... Soil Vapor TPH, VOCs, naphthalene, and methane ...
 
... 1.    Include any additional volatile additives in soil vapor samples if suspected to be present. 2.    VOCs ...
 
... provided in Table 9-5. Petroleum contamination in soil, water or air/soil vapors should be evaluated in terms of both TPH and a short list of target "indicator chemicals" ...
 
...specific PAHs. Methylnaphthalenes do not need to be reported for soil vapor samples as a default. Based on data reviewed by HDOH, these compounds are unlikely to drive ...
 
... Based on data reviewed by HDOH, these compounds are unlikely to drive potential vapor intrusion hazards at petroleum release sites over TPH or benzene due to their relatively low ...
 
...in most middle distillates and residual fuels. Testing for these compounds in soil vapor also requires different sample collection and analytical methods (e.g., sorbent tubes and TO-1 ...
 
...sorbent tubes and TO-1 analysis; see Section 7.8.2). Reporting of these compounds in soil vapor samples may, however, be required at sites impacted by Manufactured Gas Plant waste. ...
 
... 9.3.1.2 Total Petroleum Hydrocarbons Soil, groundwater, and soil vapor samples must always be tested for TPH (or equivalent) in addition to targeted, individual ...
 
...material in the soil. The concentration of TPH (or equivalent) in soil vapor should always be reported as the sum of C5-C12 compounds for whole air samples and C5-C18 for ...
 
...Brewer et al 2013). As discussed above and in Section 7.8.2, results from a petroleum vapor study carried out by HDOH study indicate that C5-C8 aliphatic compounds can make up ...
 
...compounds can make up a significant if not dominant fraction of the total TPH present in vapors associated with diesel and other middle distillate fuels (HDOH 2012, 2012c). This ...
 
...of C5-C8 aliphatics to the total concentration of TPH reported in air or soil vapor samples associated with middle distillate fuels would be inappropriate, however. ...
 
...this issue, laboratories should be instructed to report TPH (or equivalent) in air or vapor samples as: 1) The sum of C5-C12 compounds for whole-air samples (e.g., summa canister samples ...
 
...data indicate that C12+ compounds make up less than 10% of the total TPH present in vapors. Designation of chromatogram patterns as "gasoline range" (e.g., C5-C12) or "diesel ...
 
...to traditional, laboratory methods for TPH in soil or water is not applicable to air and vapor samples and can be misleading. The reported concentration of TPH can then be compared to HDOH ...
 
... of both Summa canister samples and sorbent tube samples is recommended for soil vapor investigations at diesel and middle distillate sites. This is due to limitations on the ability ...
 
...both TPH and target, indicator compounds such as BTEX and naphthalene). A maximum, 50ml vapor draw might be required for sorbent tube samples due to limitations of the sorbent material ...
 
...canisters can be relied upon for the collection of future samples. If >10% of the vapor-phase TPH is associated with >C12 compounds then a combined use of Summa data and sorbent ...
 
...however, these compounds make up an insignificant (i.e., <10%) proportion of TPH vapors at typical, petroleum-release site. Reported concentrations of unidentified hydrocarbons ...
 

10.6 Field QA/QC
...is typically analyzed for volatile organic compounds in aqueous samples due to the high vapor pressure and potential for vapor migration. Non-aqueous samples collected using methanol preservation ...
 
...pressure and potential for vapor migration. Non-aqueous samples collected using methanol preservation techniques may also require ...
 

11.0 Handling and Analysis of Samples
...phase samples is not included in this section; guidance on handling and analysis of soil vapor or indoor air samples is presented in Section 7. Quality assurance/quality control ...
 

11.2 Sample Preservation and Hold Times
...include: sampling gravely soil matrix (if using EnCore® type samplers), spillage or evaporation of pre-weighed chemical preservatives, shipping restrictions involving chemical ...
 

Contents
... 13.2 DEVELOPMENT OF VAPOR INTRUSION SCREENING TOOLS   ...
 
... 13.2.2 VAPOR ATTENUATION IN TROPICAL VERSUS COLD CLIMATES ...
 

13.0 Environmental Hazard Evaluation
...of the most pressing hazards (e.g., discharges of free product into storm sewers, vapor intrusion into overlying buildings) and other site-specific considerations. Contamination ...
 

13.1 Target Environmental Hazards
... - Vapor Intrusion ...
 
...in soil via incidental ingestion, dermal absorption and inhalation of vapors or dust in outdoor air. ...
 
... - Vapor Intrusion ...
 
... Vapor Emissions ...
 
... odor and nuisance concerns and in some cases even result in explosive levels of vapors in soil gas. Although it may seem counterintuitive, it is quite possible for soil that is ...
 
...by direct exposure hazards (e.g., arsenic, lead, polychlorinated biphenyls [PCBs]). Vapor intrusion typically drives environmental hazard for soil contaminated with volatile carcinogens, ...
 
...water toxicity hazards are almost always identified for contaminated aquifers. Potential vapor intrusion hazards will also usually be identified for groundwater contaminated with carcinogenic, ...
 
...offsite and discharge into a surface water body. Free product also poses potential vapor intrusion hazards for nearby buildings as well as potential explosive, subsurface vapor hazards. ...
 
...intrusion hazards for nearby buildings as well as potential explosive, subsurface vapor hazards. Other potential environmental hazards may require attention at some sites, including ...
 

13.2 Tier 1 Environmental Action Levels
... ' 13.2 DEVELOPMENT OF VAPOR INTRUSION SCREENING TOOLS The overview of vapor intrusion and the collection of soil ...
 
...INTRUSION SCREENING TOOLS The overview of vapor intrusion and the collection of soil vapor samples provided in Section 7 and the following ...
 
...intrusion and the collection of soil vapor samples provided in Section 7 and the following discussions regarding the development ...
 
...soil gas as well as soil and groundwater action levels for screening of potential vapor intrusion hazards. The action levels are periodically updated as additional field data are ...
 
...are periodically updated as additional field data are obtained and the understanding of vapor intrusion risk progressively improves. A key part of the action levels is the assumed ...
 
... A key part of the action levels is the assumed attenuation of subsurface vapors as they intrude a building and mix with indoor air. This section discusses the technical ...
 
... to caution against use of the HDOH soil gas, soil and groundwater action levels for vapor intrusion in colder areas of the US where heating and overall building ventilation efficiency ...
 
...and overall building ventilation efficiency could lead to less attenuation of intruding vapors and an increased risk of adverse impacts to indoor air. 13.2.1 DERIVATION ...
 
...Soil Gas attenuation factors used to develop the HDOH soil, groundwater, soil gas ("vapor") and indoor air action levels for potential vapor intrusion hazards are summarized below. ...
 
...and indoor air action levels for potential vapor intrusion hazards are summarized below. A more detailed discussion is provided in Appendix ...
 
...of the action levels is an important aspect of preparation of a Conceptual Site Model for vapor intrusion as part of a vapor intrusion investigation, as discussed in Section 7.2. Model ...
 
...intrusion as part of a vapor intrusion investigation, as discussed in Section 7.2. Model and exposure assumptions ...
 
... exposure models for ambient air (see USEPA, 2012a). Shallow soil gas action levels for vapor intrusion are calculated by dividing the indoor air goal by an Indoor Air:Subslab Soil Gas ...
 
...by an Indoor Air:Subslab Soil Gas attenuation factor that reflects dilution of subsurface vapors upon mixing with indoor air: Default Indoor Air:Subslab ...
 
...correlative, shallow soil gas action levels. Although based on models for subslab soil vapors, the "shallow soil gas" action levels are intended to be applied to soil vapor samples collected ...
 
...the "shallow soil gas" action levels are intended to be applied to soil vapor samples collected within 5 feet of a building slab or crawl space for initial screening purposes ...
 
...HDOH, 2011; see also Section 7.6.2). Subslab soil gas samples located near potential vapor intrusion pathways (e.g., utility gaps in floors) are considered to be most reliable for evaluation ...
 
...utility gaps in floors) are considered to be most reliable for evaluation of potential vapor intrusion hazards under current site conditions. The attenuation factors are calculated ...
 
...the approximated, indoor-air exchange rate (IAER) by the approximated flux of subsurface vapors through the floor of the building using the same units (see HDOH, 2011): ...
 
...2011). Note that default, IAERs and subslab, soil gas attenuation factors for use in vapor intrusion investigations have not been developed for individual areas of California (refer ...
 
... factor. A default, indoor air volume for residences of 244m3 is recommended in USEPA vapor intrusion guidance (USEPA 2004f). Assuming an IAER of 1.0/hour, this equates to an IAER in ...
 
...of 4,067 L/minute. Based in part on radon and tracer tests intrusion studies, USEPA vapor intrusion guidance recommends a default, vapor flux rate ("Qsoil") through the floors of residential ...
 
...intrusion guidance recommends a default, vapor flux rate ("Qsoil") through the floors of residential homes of 5L/minute (see USEPA 2004f). ...
 
...of HDOH residential soil gas action levels (see HDOH, 2011). Note that the USEPA vapor intrusion model for groundwater calculates a vapor flux rate of 67.4 cm3/second or 4.0 ...
 
...intrusion model for groundwater calculates a vapor flux rate of 67.4 cm3/second or 4.0 L/minute, based on input, default building parameters (see ...
 
...HDOH, 2011, Appendix 4). This generates an AF of 0.0010 (1/1,017) as used the groundwater vapor intrusion models. The AFs used between the soil gas and groundwater models are therefore consistent. ...
 
...factor falls within the lower 25% of AFs calculated from empirical data in the USEPA vapor intrusion database for chlorinated solvent sites (USEPA 2012b). This is reasonable for tropical ...
 
...noted earlier, over pressurization of buildings due to air conditioning will also inhibit vapor intrusion in these areas. 13.2.2 VAPOR ATTENUATION IN TROPICAL VERSUS COLD CLIMATES ...
 
...intrusion in these areas. 13.2.2 VAPOR ATTENUATION IN TROPICAL VERSUS COLD CLIMATES Selection of an attenuation factor that ...
 
...is reasonable for the scenario under consideration is important. Attenuation of intruding vapors can be expected to vary widely with respect to different climate zones and building designs. ...
 
...to develop residential subslab, soil gas action levels for screening of potential vapor intrusion hazards in Hawai�i. As discussed in the next section, an AF of 0.001 is coincident ...
 
...of air conditioning for much of the year, which can prevent the intrusion of subsurface vapors into the building. Radon studies suggest that opening windows can both increase natural ventilation ...
 
...opening windows can both increase natural ventilation and decrease the rate of subsurface vapor entry into buildings (e.g., Cavallo et al., 1992). This alone can reduce the attenuation ...
 
... factor by an order of magnitude or more (i.e., greater attenuation of intruding vapors). Agencies in colder areas of the US mainland may recommend the use of a higher, more ...
 
...a higher, more conservative AF for general screening purposes (i.e., less attenuation of vapors assumed due to poorer building ventilation). This is due to both an expected, increased ...
 
...poorer building ventilation). This is due to both an expected, increased average annual vapor flux rate through building floors due to heating for large portions of the year as well as ...
 
... portions of the year as well as decreased ventilation during these same periods. Vapor intrusion risks are much higher in these areas in comparison to Hawai�i. Significant ...
 
... considerations. Empirical databases are being reviewed to help develop initial AFs and vapor intrusion guidance. As discussed below, other factors, including permit requirements for minimum ...
 
...air exchange rate data, "climate zones" based on annual heating and cooling days and vapor flux data from radon studies could be used to help develop region-specific AFs. ...
 
...databases are very useful for development of tools to quickly screen sites for potential vapor intrusion hazards. A large database of paired, indoor air and soil vapor samples collected ...
 
...intrusion hazards. A large database of paired, indoor air and soil vapor samples collected from sites impacted by chlorinated solvents has been compiled by USEPA (USEPA ...
 
...2013). The database for chlorinated solvent sites provides clear evidence of vapor intrusion related impacts to indoor air at well-studied sites like Endicott, New York. Even ...
 
...the buildings tested with respect to contamination, it does help to put the risk posed by vapor intrusion in perspective. The majority of the indoor air samples (>75%) were also collected ...
 
... after the building ventilation system had been turned off and a flow of subsurface vapors into the building had been induced by placing large, exhaust fans placed in doorways. ...
 
... in doorways. These approaches are useful for identification of worst-case, vapor intrusion scenarios and estimation of the range of vapor attenuation in indoor air in general. ...
 
...intrusion scenarios and estimation of the range of vapor attenuation in indoor air in general. For example, Indoor Air: Subslab Soil Gas Attenuation ...
 
...dividing the concentration of a VOC in indoor air by the concentration of the VOC in soil vapor immediately beneath the building slab. These factors can then be used to develop soil gas action ...
 
... then be used to develop soil gas action (screening) levels to screen sites for potential vapor intrusion hazards based on subsurface, soil vapor data. This approach must be used with ...
 
...intrusion hazards based on subsurface, soil vapor data. This approach must be used with caution, however (see USEPA, 2012b). Contributions ...
 
...2012b). Contributions from indoor or outdoor sources can mask the true attenuation of vapors in indoor air and underestimate actual attenuation. Concentrations of VOCs in indoor air within ...
 
...of VOCs in indoor air within anticipated background can also mask scenarios where no vapor intrusion is in fact occurring. In this case, a calculated "attenuation factor" would simply ...
 
...samples collected under the slab and not be associated with the attenuation of intruding vapors. The use of indoor air samples collected from basements could further exacerbate this problem, ...
 
...the usefulness of empirical databases or downplay the need to investigate potential vapor intrusion hazards. These databases, in spite of their inherent shortcomings, help to initially ...
 
... indoor air:subslab soil gas attenuation factors and are an important component of vapor intrusion screening tools. Attenuation factors can also be estimated based on the estimated ...
 
...tools. Attenuation factors can also be estimated based on the estimated volume of vapor intruding a building per unit time in comparison to the volume of fresh air entering the building ...
 
...fresh air entering the building over the same time period. This is the approach used in vapor intrusion models published by the USEPA (2004f). Vapor flux into homes and buildings has been ...
 
...intrusion models published by the USEPA (2004f). Vapor flux into homes and buildings has been extensively studied as part of radon investigations. ...
 
...of a ventilation problem that is exacerbating impacts to indoor air associated with vapor intrusion. This analysis indicates that the HDOH shallow soil gas action levels should ...
 
...in colder regions where buildings are more poorly ventilated. This also applies to vapor intrusion screening levels presented in the Pacific Basin edition of the EHE guidance if used ...
 
...tools for development of region-specific, attenuation factors and overall evaluation of vapor intrusion risk (e.g., see USEIA, 2012). 13.2.5 USE OF REASONABLE MAXIMUM ...
 
...as 0.05 (1/20) or even higher are calculated for 5% of the samples included in the USEPA vapor intrusion database (see USEPA, 2012b). Use of this AF for general screening purposes has been ...
 
...An AF of 0.05 represents the worst of these basements (i.e., basements with highest vapor flux rate and/or lowest ventilation rate). The use of AFs associated with worst-case, ...
 
...general screening purposes would help ensure that all potentially significant cases of vapor intrusion will be caught. Adversely, however, the combined use of a worst case vapor attenuation ...
 
...intrusion will be caught. Adversely, however, the combined use of a worst case vapor attenuation and exposure scenario with a conservative, target risk (e.g., target cancer risk ...
 
...purposes could cause a large number of homes and buildings to be flagged for potential vapor intrusion hazards when no further action would ultimately be required. Resulting soil gas screening ...
 
... Section 7.7.1). Virtually any detection of volatile chemicals in soil, groundwater, soil vapors, or indoor air would trigger a time and cost consuming assessment of atypical vapor intrusion ...
 
...or indoor air would trigger a time and cost consuming assessment of atypical vapor intrusion concerns. The assessments would in most cases be inconclusive. A more careful review ...
 
...years, especially for areas of the US where buildings are indeed highly susceptible to vapor intrusion. Current discussions are reminiscent of debates in the 1980s and 1990s regarding ...
 
...1991a, 1991b, 2011a). The same is also likely to be true for exposure to subsurface vapors that intrude into a building under a worst-case, building ventilation scenario. Under such ...
 
...a worst-case, building ventilation scenario. Under such conditions, the risk posed by vapors associated with indoor and outdoor sources of volatile chemicals is likely to be far greater ...
 
...is likely to be far greater than the contribution to risk posed by the intruding vapors (see also MADEP, 2002b, USEPA, 2011a). This is important, as the consideration of a "pica ...
 
...important, as the consideration of a "pica house" exposure scenario and associated soil vapor attenuation factors for general screening purposes will flag a significantly larger number ...
 
...purposes will flag a significantly larger number of houses and buildings for potential vapor intrusion hazards. Based on the sample data in the USEPA database, concentrations of targeted ...
 
...of these cases, making a clear determination of impacts potentially associated with vapor intrusion impossible, but leaving a stigma on the homes and buildings evaluated. ...
 
...published screening levels and guidance be adequately conservative to identify high-risk, vapor intrusion sites. It is equally important, however, that the screening levels and guidance be ...
 
...maximum, Indoor Air:Subslab Soil Gas AF can be calculated based on a default, vapor flux rate for under-pressured buildings and minimum ventilation requirements for residential ...
 
...would ultimately be required and allow focus on sites that pose a high risk for adverse, vapor intrusion. For low-risk sites, informal recommendations should also be made to review the adequacy ...
 
...rare cases, a more detailed evaluation of site-specific factors associated with intrusion vapor intrusion and the use of potentially more conservative action levels may be required. ...
 

13.3 Steps to Environmental Hazard Evaluation
... as assumed in the default, Tier 1 CSMs and EALs. Soil action levels for direct exposure, vapor intrusion and gross contamination hazards are higher (i.e., less stringent) than correlative ...
 
...because land use does not alter the threat to groundwater. Groundwater action levels for vapor intrusion hazards are also higher for a commercial/industrial land use scenario. Action levels ...
 
...13-5c), the input concentration of benzene in soil (5.1 mg/kg) causes direct exposure, vapor intrusion and leaching hazards to be flagged. Potential impacts to terrestrial ecological receptors ...
 
...concentration of volatile contaminants in soil or groundwater exceed action levels for vapor intrusion concerns, then soil gas data can be collected to more closely evaluate this potential ...
 
...soil gas data is very useful (and strongly recommended) for more detailed evaluations of vapor intrusion concerns. The inclusion of soil gas action levels in this guidance helps expedite ...
 
...some cases (e.g., direct exposure to non-volatile contaminants) and not in others (e.g., vapor intrusion or leaching hazards). Using the detailed action levels to understand the ...
 
...used as a source of drinking water is obviously important. Expeditious actions to address vapor intrusion hazards posed by contaminated soil are usually warranted. In contrast, long-term ...
 

13.4 Preparation of Environmental Hazard Evaluation Reports
...hazards posed by contaminated soil. In particular, the RSLs do not address potential vapor intrusion, leaching or gross contamination hazards and may not adequately address cumulative ...
 

13.5 Human Health Risk Assessments
...petroleum-related contamination in particular, soil gas data often indicate a much lower vapor intrusion hazard than predicted by simple comparison of soil or groundwater data to HEER Office ...
 
... Vapor Intrusion ...
 
...and subsequent evaluation of risk to human health (site-specific vapor intrusion model) ...
 
... Vapor Intrusion ...
 
...and subsequent evaluation of risk to human health risk (site-specific vapor intrusion model) ...
 
...contamination of groundwater. Soil or groundwater data flagged for potential vapor intrusion almost always indicates that soil gas samples should be collected at the site. The ...
 
...at the site. The model used to develop the soil and groundwater actions levels for vapor intrusion hazards estimates the concentration of a volatile contaminant in shallow soil gas ...
 
...issues to consider include: 1) What areas of the site pose potential direct exposure or vapor intrusion hazards? 2) What areas of the site pose potential leaching hazards? and 3) In what ...
 
... leaching hazard. In a third area, soil contaminated with chlorinated solvents poses vapor intrusion hazard, a direct exposure hazard and a leaching hazard. In a fourth area, soil contaminated ...
 
...mobile contaminants often pose a combination of several environmental hazards, including vapor intrusion, direct exposure and leaching (e.g., PCE). The environmental hazard ...
 
...short time frame will, in contrast, require some type of impermeable cap. Subslab vapor mitigation systems will be required for new buildings placed within the vapor intrusion hazard ...
 
...mitigation systems will be required for new buildings placed within the vapor intrusion hazard area. Indoor air studies may be needed for existing buildings located in this ...
 
...environmental hazard(s) posed in a given area of the site including capping, vapor mitigation systems, offsite disposal, etc. (see text). ...
 
...levels for the noted hazard. Aggressive remediation should focus on removal of vapor intrusion hazard so property can be redeveloped. Aggressive remediation of groundwater ...
 
...evaluated. This could include restrictions on future use of the property, installation of vapor mitigation systems under buildings, capping of contaminated soil to prevent exposure or leaching, ...
 

13.6 Ecological Risk assessements
...of contaminants in soil ("direct exposure"), impacts to water supply wells, intrusion of vapors or methane into overlying structures (including explosive hazards) and discharges of free ...
 

15.6 Site Cleanup Process
...remediate contamination that is causing immediate environmental hazards (e.g. vapor intrusion into a building) and prepare an Environmental Hazard Management Plan (EHMP) to address ...
 

16.2 Setting Remedial Action Objectives and Conducting a Remedial Alternatives Analysis
... contaminant in a smaller volume. Examples include: Soil vapor extraction to extract volatile contaminants from subsurface soils Groundwater extraction, ...
 
...by covering the soil with a concrete cap On-site containment of soil gas with vapor barriers or active ventilation systems On-site containment of contaminated groundwater ...
 

18.5 Document Outlines
... 5.4 Soil Vapor Investigation   ...
 
... 5.5 Soil Vapor Sampling Activities   ...
 
...significant, environmental concerns remain but active remediation (e.g., excavation, soil vapor extraction, etc.) is no longer practical. This type of letter is often used when further excavation ...
 

19.0 Site Closures
...significant environmental concerns remain, but active remediation (e.g., excavation, soil vapor extraction, etc.) is no longer practical. This status may be helpful to site owners, financial ...
 

19.1 Site Closure Scoping
...operation and maintenance of an active engineering control, such as an active vapor mitigation system. Failing to implement, maintain, and report on required monitoring. ...
 
...exposure, such as constructing a new building on the site without the necessary vapor mitigation measures. Sale of the property without appropriate disclosures ...
 

19.3 Closures with Use Restrictions
... and resulting data may indicate a potential environmental hazard from subsurface vapor intrusion into indoor air spaces. The site may be closed with restricted use, but engineering ...
 
...The site may be closed with restricted use, but engineering controls (e.g., an active vapor mitigation system); institutional controls (i.e., an environmental covenant to restrict land ...
 

19.4 No Further Active Remediation Letter
...significant, environmental concerns remain but active remediation (e.g., excavation, soil vapor extraction, etc.) is no longer practical. This type of letter is often used when further excavation ...
 

19.6 Environmental Hazard Management Plan
...included. This could include restrictions on future use of the property, installation of vapor mitigation systems under buildings, capping of contaminated soil to prevent exposure or leaching, ...
 

19.7 Institutional and engineering Controls
... which are methods of exposure prevention by physical means (for example, an active vapor mitigation system to prevent subsurface vapor intrusion into indoor air spaces). Institutional ...
 
...mitigation system to prevent subsurface vapor intrusion into indoor air spaces). Institutional controls alone are generally not sufficient ...
 
...an engineering control of contaminated sediments, as well. Soil Vapor Contamination Vapor barriers � impermeable materials are placed beneath a proposed building ...
 
...Contamination Vapor barriers � impermeable materials are placed beneath a proposed building site to prevent ...
 
...materials are placed beneath a proposed building site to prevent subsurface vapor intrusion into indoor air spaces. Active vapor removal systems should be considered for ...
 
...intrusion into indoor air spaces. Active vapor removal systems should be considered for sites with significant soil gas issues in which ...
 
...a suction fan, which may be vented above the roof of the building, or connected to a vapor treatment system such as a thermal oxidizer or granular activated carbon. ...
 

Log of TGM Updates
... 7 Soil Vapor and Indoor Air Sampling Guidance Feb 21, 2014 ...
 

PDF Download Page
... Section 7 - Soil Vapor and Indoor Air Sampling Guidance ...
 
... Field Investigation of the Chemistry and Toxicity of TPH in Petroleum Vapors: Implications for Potential Vapor Intrusion Hazards. ...
 
...Implications for Potential Vapor Intrusion Hazards. 13.8mb ...
 

Additional Guidance Documents" Language="VB" MasterPageFile="~/lib/Content.master
...Field Investigation of the Chemistry and Toxicity of TPH in Petroleum Vapors This Q&A provides responses to common questions ...
 
...responses to common questions regarding the August 2012 HDOH TPH vapor report. Reference: HDOH 2012c ...
 
...evaluation of environmental hazards, including direct exposure, vapor intrusion, leaching and contamination of groundwater, impacts to drinking ...
 

7.10 Documentation of Soil Vapor or Indoor Air Sampling
...Guide (MADEP 2002b); DoD: Tri-Services Handbook for the Assessment of the Vapor Intrusion Pathway (DoD 2008); Massachusetts: Vapor Intrusion Guidance (MADEP 2010); ...
 
...Intrusion Pathway (DoD 2008); Massachusetts: Vapor Intrusion Guidance (MADEP 2010); and California: Guidance for the Evaluation ...
 
...and California: Guidance for the Evaluation and Mitigation of Subsurface Vapor Intrusion to Indoor Air (CalEPA 2011). Due to potential complications ...
 
...indoor and outdoor sources of VOCs, the collection of indoor air samples as part of a vapor intrusion study will rarely be practical or recommended (see Sections 7.2 and 7.3). ...
 
...collection of indoor air samples is only recommended if concentrations in subslab soil vapor exceed 1,000 times (residential) to 2,000-times (commercial/industrial) anticipated background ...
 
...demonstrate a link between apparent impacts to indoor air and the intrusion of subsurface vapors (refer to Section 7.1 and HEER Office EHE guidance, HDOH 2011). This includes the ...
 
...on shallow groundwater), concentrations of targeted VOCs in source area and subslab soil vapor samples, presence or absence of apparent pathways for vapor intrusion, building ventilation ...
 
... samples, presence or absence of apparent pathways for vapor intrusion, building ventilation design and operation (e.g., likelihood to be over- or under-pressured) ...
 
...or risk, it may be also useful to collect a sample(s) directly from a point of suspected vapor entry, including bathrooms, utility rooms or other areas where utilities protrude through the ...
 
...be evaluated and taken into consideration. For example, buildings may be more prone to vapor intrusion during periods of the year when air conditioning is not routinely used and ...
 
...due to wind effects is increased. Buildings could also be more susceptible to vapor intrusion during dry periods of the year due to the exposure of subsurface smear zones as the ...
 
...If collecting a combination of indoor air samples, outdoor air samples, and sub-slab soil vapor samples for one project, the indoor and outdoor air samples should be collected concurrently, ...
 
... collected concurrently, immediately followed by collection of the sub-slab soil vapor samples. The collection of sub-slab samples simultaneously with the indoor air samples it not ...
 
...ambient air samples should be collected when conducting indoor air sampling as part of a vapor intrusion study. Ambient air samples are important for evaluation of potential outdoor sources ...
 
...VOCs. Like indoor air, ambient air can contain a number of VOCs typically targeted for vapor intrusion studies. Examples include TPH, BTEX and other petroleum-related chemicals associated ...
 
...It is recommended that a checklist be used as a guide when conducting building surveys. Vapor intrusion assessment guidance manuals from the USEPA (USEPA 2004e), the Interstate Technology and Regulatory ...
 
...building survey checklists, as do several other state guidance documents (see also vapor intrusion discussion in HEER EHE guidance; HDOH 2011). As part of the building ...
 
...guidance; HDOH 2011). As part of the building survey, potential preferential vapor intrusion pathways should also be evaluated. Utility corridors can act as contaminant migration ...
 
...pathways allowing VOCs to travel long distances. Primary entry points for subsurface vapors include bathrooms, kitchens and utility rooms where water, sewer, gas, electric and ...
 
...lines penetrate the floor. Wall outlets for electrical fixtures can also serve as a vapor intrusion pathway. Depending on the COPC, screening for VOCs using direct reading ...
 
...the parts per billion (ppb) range, and are best used for screening at points of potential vapor entry, locating indoor VOC sources, or identifying acute exposure or potentially explosive ...
 
...or identifying acute exposure or potentially explosive situations. Note that petroleum vapors are dominated by aliphatic compounds. PIDs primarily target aromatic compounds and are not ...
 
... target aromatic compounds and are not good indicators of total TPH levels in soil vapors without inclusion of a correction factor (ASTM 2006f; refer also to HDOH 2012). This is especially ...
 
... refer also to HDOH 2012). This is especially important to remember for aromatic-poor vapors from diesel fuel of other middle distillate fuels. 7.11.2 Indoor ...
 
...within the building and any sensitive populations that may be exposed to the contaminated vapors. In structures with basements, both the occupied living areas and basement areas should be ...
 
...with the latter most commonly selected (see Section 7.13). For vapor intrusion studies, the suite of VOCs targeted for Indoor and outdoor air samples should be ...
 
...for Indoor and outdoor air samples should be identical to the suite targeted for soil vapor and identified in subslab soil vapor samples. Inclusion of additional VOCs can complicate the ...
 
...and identified in subslab soil vapor samples. Inclusion of additional VOCs can complicate the evaluation of impacts associated purely ...
 
...of additional VOCs can complicate the evaluation of impacts associated purely with vapor intrusion. 7.11.6 Indoor-Outdoor Air Sample Logs A sample ...
 

7.10 Documentation of Soil Vapor or Indoor Air Sampling
... ' 7.12 PASSIVE SOIL VAPOR AND INDOOR AIR SAMPLE COLLECTION PROCEDURES ...
 
... Figure 7-33: Installing a Passive Soil Vapor Sample Collector by Hand The hole is drilled using a roto-hammer. The soil vapor sample ...
 
...Sample Collector by Hand The hole is drilled using a roto-hammer. The soil vapor sample collector is installed using an insertion rod. The hole is then covered. ...
 
... Figure 7-34: Example Plume Map from Grid-based Passive Soil Vapor Survey. Passive sampling can be applied to either soil ...
 
... Passive sampling can be applied to either soil vapor or indoor air. Although the principle is the same in application to these media, the techniques ...
 
...retrieval and analysis are different. 7.12.1 Passive Sampling of Soil Vapor Implementing a passive soil vapor sampling strategy in the field requires careful ...
 
... Implementing a passive soil vapor sampling strategy in the field requires careful consideration of the pertinent sampling variables, ...
 
...locations for passive sampling is based upon the same considerations as active soil vapor methods: project objectives and the need for adequate coverage. Predetermined and widely spaced ...
 
... source as possible in order to reduce the chance of placing the sampler in a pocket of vapor-free soil in an otherwise contaminated area. In addition, collectors buried close to the surface ...
 
...of time. The key assumption that is made when interpreting passive soil vapor data is that each collector is exposed to the same quantity of soil vapor. Therefore, it is ...
 
...data is that each collector is exposed to the same quantity of soil vapor. Therefore, it is most important that passive collectors within a sampling program be deployed ...
 
... QA/QC: The most important factors affecting the quality of passive soil vapor data is consistency of deployment and potential contamination of the samplers. Sampling ...
 
...to the laboratory. There are several vendors of passive soil vapor sample collectors and those vendors should be consulted regarding specific installation procedures ...
 
... collector is shown in Figure 7-33. An example plume map from a grid-based passive soil vapor survey is shown in Figure 7-34. 7.12.2 Passive Sampling of ...
 

7.10 Documentation of Soil Vapor or Indoor Air Sampling
... ' 7.13 SOIL VAPOR AND INDOOR AIR SAMPLE ANALYSIS The analytical methods selected for analyzing soil vapor ...
 
...AND INDOOR AIR SAMPLE ANALYSIS The analytical methods selected for analyzing soil vapor or indoor air samples depend on a number of factors. These include the targeted VOCs, desired ...
 
...and reporting limits and the manner in which the sample is collected. In Hawai`i, soil vapor or indoor air samples are in most cases forwarded to a fixed analytical laboratory ...
 
...(VOCs) A variety of analytical methods are available to measure soil vapor samples all of which give accurate results. Table 7-10 gives a summary of the available ...
 
...as the sum of C5 to C12 (Summa canister samples) and/or C5-C18 (sorbent tube samples) for vapors associated with all types of petroleum fuels, including diesel and other middle distillate ...
 
... of TPH compounds as �gasoline-range� or �diesel-range� is not applicable to soil vapors. As discussed in Section 7.13.1.2, vapors associated with diesel and other middle distillate ...
 
...As discussed in Section 7.13.1.2, vapors associated with diesel and other middle distillate fuels could, in theory, include ...
 
...and to a lesser degree aromatic compounds (see HDOH 2012). Inclusion of heavier, vapor-phase compounds in the measurement of TPH will require the use of a sorbent method (e.g., ...
 
...VOCs and TPH (see Section 7.8.2). This will almost always be the case for soil vapors associated with petroleum. If initial sorbent data (or prior knowledge at a similar site) ...
 
...petroleum. If initial sorbent data (or prior knowledge at a similar site) indicates that vapors are dominated (e.g., >90%) by C5-C12 compounds then subsequent TPH data can be obtained ...
 
...for its selection, and analytical results should be fully documented in the final soil vapor or indoor air investigation report. ...
 
... Table 7-10 Summary of Soil Vapor & Indoor Air Analytical Methods1 ...
 
...can be reanalyzed as needed. TO-13 can be used to quantify heavier TPH in vapors but may not adequately capture light-end VOCs (consult the laboratory). ...
 
... Table 7-11 HDOH-Recommended Laboratory Analytical Methods for Soil Vapor or Indoor Air Contaminants and Leak Detection Compounds ...
 
...HDOH and laboratory staff, The best laboratory method to test for TPH in soil vapors appears to be a combination of both TO-15 (Summa canister samples) and TO-17 (sorbent ...
 
...in Section 9 and the HEER Office EHE guidance (HDOH 2011 and updates), testing of vapors associated with petroleum should include a short list of target indicator compounds (e.g., ...
 
... Section 9, Table 9-5. Total Petroleum Hydrocarbons represents the sum of the vapor-phase, aliphatic and non-targeted, individual aromatic compounds. This is sometimes subdivided ...
 
...released. A distinction between TPHg and TPHd compounds is misleading for vapor-phase petroleum, however, since vapors from diesel and other middle distillate fuels or fuels ...
 
...petroleum, however, since vapors from diesel and other middle distillate fuels or fuels that include middle distillates (e.g., ...
 
...of lighter end compounds, especially C5-C8 aliphatics. Requesting the lab to report vapor-phase TPH as the equivalent of �TPHd� (i.e., sum of C10+ compounds) could significantly ...
 
...C10+ compounds) could significantly underestimate the actual concentration of TPH in soil vapors. This issue was investigated and discussed in the HEER Office study Field Investigation ...
 
...HEER Office study Field Investigation of the Chemistry and Toxicity of TPH in Petroleum Vapors: Implications for Potential Vapor Intrusion Hazards (HDOH 2012, 2012c; Brewer ...
 
...Implications for Potential Vapor Intrusion Hazards (HDOH 2012, 2012c; Brewer et al 2013). The study suggested ...
 
...et al 2013). The study suggested that the proportion of C5-C8 aliphatic compounds in vapors associated with middle distillate fuels is highly variable but can be up to 50% or more of ...
 
...fuels is highly variable but can be up to 50% or more of the total TPH. Excluding these vapors from the TPH analysis can significantly under-report the total TPH present in a vapor sample. ...
 
...from the TPH analysis can significantly under-report the total TPH present in a vapor sample. The study also indicated that individual, targeted aromatic compounds such as BTEX ...
 
... aromatic compounds such as BTEX typically make up less than 1% of the total petroleum vapors present. Vapor intrusion risk associated with the TPH fraction of petroleum vapors ...
 
...present. Vapor intrusion risk associated with the TPH fraction of petroleum vapors has only recently begun ...
 
...intrusion risk associated with the TPH fraction of petroleum vapors has only recently begun to be investigated in detail (e.g., Brewer et al 2013; ...
 
...to toxicity factors and action levels, the higher proportion of TPH aliphatics in the vapors causes these compounds to be the primary risk driver with respect to potential vapor intrusion ...
 
...causes these compounds to be the primary risk driver with respect to potential vapor intrusion concerns. Ongoing evaluations of soil gas field data will help address the lack of ...
 
...field data will help address the lack of published information on the relative risk of vapor intrusion (quantitatively considered) posed by TPH versus benzene and other individual compounds. ...
 
...highlights the potential problems associated with one-time sampling events and limited vapor points (see Section 7.10.1). For vapors associated with gasoline-only ...
 
... points (see Section 7.10.1). For vapors associated with gasoline-only releases, TPH (or equivalent) should be reported as the sum ...
 
...the carbon range from C5 to C12 (non-BTEX aromatics typically reported to C10). For vapors associated with middle distillate (and heavier) fuels, including diesel, TPH should be ...
 
...range� TPH in the sample, since doing so excludes reporting of C5-C9 aliphatics in soil vapors and could significantly underestimate the total concentration of TPH-related compounds. As ...
 
... TPH soil gas action levels; HDOH 2011). The concurrent collection of soil vapor samples using both a Summa canister and a sorbent tube is recommended for the investigation ...
 
...a Summa canister and a sorbent tube is recommended for the investigation of subsurface vapors associated with diesel or other middle distillate fuels (see Section 7.8). The draw ...
 
...7.8.2). The Summa canister sample is likely to be more representative of subsurface vapors, given its larger volume. This sample should be collected first, following purging, ...
 
...soil. The sorbent tube sampling train should then be attached to the vapor point and a shut-in leak test performed. Following successful completion of a shut-in test, ...
 
...can be drawn that a significant proportion of C12+ compounds are not present in the soil vapors and Summa canister samples can be used for future sample collection. A review of the TO-17 ...
 
... for the sample can also be helpful to determine if a significant proportion of the TPH vapors consists of compounds greater than C12. Vapor-phase TPH data for middle distillate ...
 
...consists of compounds greater than C12. Vapor-phase TPH data for middle distillate release sites that do not include both light- and heavy-end ...
 
...end compounds do not make up a significant proportion (e.g., >10%) of the total vapors. If the lab cannot report lighter-end compounds with their current setup then both �TPHg� ...
 
...a mixture of a high proportion of more toxic, C9-C12 aliphatic compounds in petroleum vapors. These compounds are more typically associated with diesel and other middle distillate fuel ...
 
...compounds are more typically associated with diesel and other middle distillate fuel vapors than vapors from gasoline. As a result, the default action levels may be excessively conservative ...
 
...than vapors from gasoline. As a result, the default action levels may be excessively conservative ...
 
... gasoline. As a result, the default action levels may be excessively conservative for vapor intrusion evaluations of gasoline-only release sites. As discussed in the HDOH EHE guidance ...
 
... levels can also be developed based on the average carbon range makeup of petroleum vapors (refer to HDOH 2012). Laboratory gas chromatograms should be obtained and included with ...
 
...and action levels are used. This is necessary to ensure that the total concentration of vapor-phase TPH does not pose an unacceptable health risk. This is done by dividing the reported ...
 
...the calibration procedure used by the laboratory. Is calibration done using a liquid or a vapor standard? The latter will provide more accurate data. Were typical gasoline and diesel calibration ...
 
... Therefore, the calibration procedure should be fully documented in the final soil vapor or indoor air investigation report. 7.13.2 Choosing the Analytical Method ...
 
...questions should be considered prior to the selection of analytical methods for soil vapor or indoor air samples (API 2005): What are the targeted chemicals ...
 
...targeted chemicals should be limited to chemicals identified in subslab or subsurface vapor samples. The vapor intrusion risk calculated for indoor air data should be specific to ...
 
...samples. The vapor intrusion risk calculated for indoor air data should be specific to the targeted, subsurface ...
 
...is important to determine the lowest concentrations of chemicals of concern in soil vapor or other analytes that are expected to be required for evaluation of the subsurface ...
 
... other analytes that are expected to be required for evaluation of the subsurface vapor intrusion pathway and general site investigation needs. Refer to the EALs for indoor air ...
 
...field data, indicate that concentrations of chemicals of concern in soil vapor will be high? If concentrations of chemicals of concern or other analytes in soil vapor ...
 
...will be high? If concentrations of chemicals of concern or other analytes in soil vapor are anticipated to be high, then the analytical method selected should address high ...
 
...of VOCs are anticipated, solid waste program methods for analysis of soil vapor samples typically reserved for landfill gas samples may be appropriate (USEPA 1998b). ...
 
...HDOH does not currently require analysis labs in Hawai`i to be certified for soil vapor analyses; however, the HEER Office recommends that lab certifications and/or other lab ...
 
...real time results. Are the analytical methods appropriate for the soil vapor samples? Analytical methods are periodically updated with newer techniques. It is suggested ...
 
...9, it is important to also measure the total petroleum hydrocarbon concentration in soil vapor at petroleum hydrocarbon impacted sites. The total petroleum hydrocarbon measurement should ...
 
... range organics� does not apply to indoor air or soil gas. This is because petroleum vapors from diesel can include a significant and even dominant proportion of lighter, aliphatic compounds ...
 
...The higher, relative volatility of these compounds causes these compounds to dominate vapors associated with diesel and other middle distillate fuels. The currently ...
 
...fuels. The currently preferred laboratory method to test for TPH in soil vapors for final decision making purposes is a combination of both TO-15 (Summa canister samples) ...
 
...with Method TO-17 (or acceptable alternative) are capable of reporting the full range of vapor-phase, hydrocarbon compounds present in a sample, including aliphatics, aromatics and oxygenates. ...
 
...toxic than shorter-chain hydrocarbons and their presence can significantly increase the vapor intrusion risk (HDOH 2012, see also HDOH 2011). Documenting the presence or absence ...
 
...Documenting the presence or absence of a significant proportion of these compounds in TPH vapors is necessary at the beginning of a site investigation. The need to continue ...
 
...standard used for the TO-17 method. Document that calibration procedure in the final soil vapor or indoor air investigation report. Detailed TPH carbon range data will ...
 
...Summa vs sorbent tube) and lab method (e.g., TO-15 vs TO-17). For vapors associated with diesel and other middle distillate fuels, sorbent tube methods that are able ...
 
...can quantify naphthalene using TO-15. Detection levels are normally adequate for soil vapor samples in comparison with correlative soil gas action levels (72 to 240 �g/m3), but may be ...
 
...can avoid the need to for multiple samples and laboratory methods, especially for soil vapor samples. Check with the laboratory if indoor air sampling is to be carried out and naphthalene ...
 
... 7.13.3 Field Analytical Methods On-site analysis can be very beneficial for vapor intrusion assessments as real-time data enable detection of preferential vapor migration sources ...
 
...intrusion assessments as real-time data enable detection of preferential vapor migration sources or pathways, allow additional sampling locations to be added (spatially or ...
 
...data and enable measurement of the leak-test tracer compound to ensure valid soil vapor samples are collected. Simple, portable instruments can provide both qualitative and quantitative ...
 
...levels. Field screening with hand-held PIDs or FIDs enable rapid identification of vapor migration routes around and into structures; although most field screening instruments are ...
 
...limited to the ppmv range for VOCs, which often do not provide sufficient sensitivity for vapor intrusion investigations. [Note that PIDs are not very sensitive to aliphatic compounds, which ...
 
... [Note that PIDs are not very sensitive to aliphatic compounds, which dominate petroleum vapors (ASTM 2006f; see also HDOH 2012). Quantitative oxygen, carbon dioxide, ...
 
...portable GC/MS (e.g. Hapsite by Inficon) is also available and gives quantitative soil vapor and indoor air analysis to levels as low as 1 ppbv. 7.13.4 Quality ...
 
...Stainless steel "T" manifold to simultaneously collect primary and duplicate soil vapor samples in 500-ml Summa canisters. Right photo: Laboratory-supplied duplicate sampling ...
 
...duplicate sampling apparatus to simultaneously collect primary and duplicate soil vapor samples in sorbent tubes. Replicates Field replicates ...
 
... Replicates Field replicates are not routinely required for soil vapor investigations. Replicate samples are collected to provide information on the reproducibility ...
 
...of a sample intended to represent a pre-specified volume of soil or more specifically the vapors held within that soil. Reproducibility is a function of both field and laboratory ...
 
... As discussed in Section 7.6.2.2, approaches for the designation of DUs in terms of soil vapors and vapor intrusion are still being studied. At this time the primary purpose of replicate ...
 
...and vapor intrusion are still being studied. At this time the primary purpose of replicate soil vapor ...
 
...intrusion are still being studied. At this time the primary purpose of replicate soil vapor samples, if collected, is to evaluate the reproducibility of data for individual sample point ...
 
...can provide some information on the spatial variability of VOC concentrations in soil vapor at the scale of the sample volume collected. Collecting larger samples also helps to ensure ...
 
...field duplicate samples can be collected at a minimum of 10% of the active soil vapor or indoor air samples collected per sampling day per laboratory (if more than one laboratory ...
 
...should be included at a minimum of one trip blank per sampling day or shipment cooler for vapor or indoor air samples collected using sorbent tubes or passive samples. Ensure that the laboratory ...
 
...An equipment blank is collected by passing clean air or nitrogen through the soil vapor probe parts (tubing, tips, sample train) into the sample container at the beginning of the ...
 
...contaminants are in the equipment. Equipment blanks are not generally necessary for soil vapor samples, since it is less likely that contamination in tubing or other equipment will in itself ...
 

7.10 Documentation of Soil Vapor or Indoor Air Sampling
...Environmental Hazard Evaluation (EHE) document for guidance on the comparison of soil vapor and indoor air data to published action levels. The interpretation of data is a key element ...
 
...significantly expedite data evaluation and decision making. 7.14.1 Soil Vapor Sample Evaluation The HEER Office EHE document provides risk-based, soil gas (soil ...
 
...Evaluation The HEER Office EHE document provides risk-based, soil gas (soil vapor) action levels and additional guidance that can be used to screen sites for potential vapor ...
 
...action levels and additional guidance that can be used to screen sites for potential vapor intrusion hazards (HDOH 2011; see also Sections 7.1 through 7.3). Section ...
 
...see also Sections 7.1 through 7.3). Section 7.10.1 discusses soil vapor sample timing and collection. Soil vapor data should initially be evaluated in ...
 
...sample timing and collection. Soil vapor data should initially be evaluated in terms of the assumed extent and magnitude of contamination ...
 
...of contamination at the subject site. Exceptionally high concentrations of VOCs in vapors in comparison to the assumed nature of source areas can usually be attributed to some combination ...
 
...can usually be attributed to some combination of the following scenarios (e.g., soil vapor concentrations significantly higher than would otherwise be predicted by soil or groundwater ...
 
...in nearby, vadose-zone soils (most common); Chemical present primarily in vapor phase (e.g., PCE vapors in dry soil beneath slab of a dry cleaner); Groundwater ...
 
... phase (e.g., PCE vapors in dry soil beneath slab of a dry cleaner); Groundwater source area closer than ...
 
...of a dry cleaner); Groundwater source area closer than ten feet from soil vapor sample point (default depth to water table used in models); Non-representative soil data (reliability ...
 
...data (e.g., heterogeneous plume with isolated �hot spots� nearby); or Relict vapor plume associated with earlier migration of more heavily contaminated groundwater through ...
 
... area releases over time. As discussed in the EHE guidance document, soil vapor data may not be sufficient as a stand-alone tool to determine if a vapor intrusion hazard is ...
 
...data may not be sufficient as a stand-alone tool to determine if a vapor intrusion hazard is present or absent. A �multiple lines of evidence� approach should be used ...
 
...present or absent. A �multiple lines of evidence� approach should be used to evaluate the vapor intrusion pathway. This includes consideration of the following factors, among others: ...
 
...and associated volume of contaminated soil necessary to sustain long-term, vapor emissions over the assumed exposure duration (e.g., six to thirty years; see Section 7.5; ...
 
... six to thirty years; see Section 7.5; can include use of mass-balanced vapor intrusion models); Design of potentially affected buildings and the completeness ...
 
... Design of potentially affected buildings and the completeness of possible vapor intrusion pathways (e.g., cracks, or gaps in the floor around utilities), including nature ...
 
...building to be consistently under-pressured, and thus more susceptible to subsurface vapors; Potential for intruding vapors to impact indoor air above known or anticipated ...
 
... Potential for intruding vapors to impact indoor air above known or anticipated background concentrations of targeted ...
 
... The first two factors are sometimes referred to as �source strength.� For a long-term, vapor intrusion risk to be present, the source strength must be significant enough to sustain an ...
 
...risk to be present, the source strength must be significant enough to sustain an average vapor flux rate above soil gas action levels for the assumed exposure duration (e.g., six to thirty ...
 
...allows investigators to more accurately assess the current or future completeness of the vapor intrusion pathway on a site-specific basis and determine if long-term, adverse impacts to indoor ...
 
...recommends a focus on subslab soil gas data for final decisions regarding potential vapor intrusion risks from multiple compounds, such as chlorinated solvents and petroleum. This is ...
 
...compounds, such as chlorinated solvents and petroleum. This is intended to target vapors at the point they could enter a building. This also takes into account attenuation from the ...
 
...account attenuation from the source area and/or biodegradation. Soil vapor sample analytical results should be initially compared to Shallow Soil Gas action levels for ...
 
...be initially compared to Shallow Soil Gas action levels for evaluation of potential vapor intrusion concerns, published in the EHE document (HDOH 2011, Table C-2 in Appendix ...
 
...soil gas are approached or exceeded, the need for the collection of additional soil vapor samples and a more thorough evaluation of potential vapor intrusion pathways should be evaluated. ...
 
...samples and a more thorough evaluation of potential vapor intrusion pathways should be evaluated. Indoor air samples may need to be collected if subslab ...
 
...(see Section 7.7). Based on past experience, scenarios where subslab soil vapor data does not suggest a potentially significant impact to indoor air (e.g., above indoor air ...
 
...a potentially significant impact to indoor air (e.g., above indoor air action levels) but vapor sample data from relatively shallow source areas exceed action levels is fairly common, especially ...
 
...of indoor air samples is only recommended when concentrations of VOCs in subslab soil vapor or other information suggest that indoor air could be impacted above anticipated, background ...
 
...background levels. As a general guide, testing of indoor air to evaluate potential vapor intrusion impacts is only recommended when concentrations of targeted chemicals in subslab ...
 
... impacts is only recommended when concentrations of targeted chemicals in subslab soil vapor are more than one-thousand times typical indoor air concentrations for residences and two-thousand ...
 
...above anticipated background levels, significant VOC levels have been documented in soil vapor samples collected immediately beneath the building slab, and clear entry points have been identified. ...
 
...be reviewed and compared to help identify contaminant concentration gradients or specific vapor intrusion points. For example, data for basements, bathrooms, kitchens, utility rooms or elevator ...
 
... If impacts to indoor air above anticipated background are identified and subslab soil vapor data as well as other lines of evidence suggest a likely subsurface source, then actions will ...
 
...If impacts to indoor air above anticipated background are not identified but subslab soil vapor concentrations exceed action levels, then measures to avoid potential future impacts to indoor ...
 
...of the building ventilation system may simply be recommended in cases where subsurface vapors are associated with a relatively small source area of petroleum-contaminated soil or groundwater. ...
 
...petroleum-contaminated soil or groundwater. In contrast, measures to eliminate potential vapor pathways might be required at a site where elevated concentrations of chlorinated solvents ...
 
...might be required at a site where elevated concentrations of chlorinated solvents in soil vapors associated with a large source area are identified immediately beneath a building slab or ...
 
... area are identified immediately beneath a building slab or in nearby, shallow soil vapor, even though adverse impacts to indoor air have not been specifically identified. ...
 
...If impacts to indoor air above anticipated background are not identified and subslab soil vapor concentrations do not exceed action levels, then no further action will generally be required ...
 
...to the subject home building. If subsurface data indicate a potentially significant vapor plume, however, then sealing of cracks and utility gaps in floors and an evaluation of the ...
 
...of clear impacts to existing buildings if source area soil, groundwater and/or soil vapor data suggest potential future vapor intrusion risks or other environmental hazards. Refer also ...
 
...data suggest potential future vapor intrusion risks or other environmental hazards. Refer also to the HDOH technical memorandum ...
 
... As a general rule a home or building should not be flagged for potential vapor intrusion hazards unless this is supported by multiple lines of evidence, including indoor ...
 
...it is more appropriate and responsible to state that �Conclusive evidence of adverse, vapor intrusion has not been documented� than an open-ended statement such as �Vapor intrusion into ...
 
...intrusion has not been documented� than an open-ended statement such as �Vapor intrusion into the home (or building) could not be discounted.� Due to the sensitivity of testing ...
 
...sources, an �innocent until proven guilty� approach for the investigation of potential vapor intrusion hazards is recommended. Precautionary measures are recommended, however, ...
 
...however, for sites where significant subsurface source exists even though adverse, vapor intrusion impacts have not been identified. As discussed above, this will typically include ...
 
... the limitations described in the EHE document (HDOH 2011), VOCs in groundwater or soil vapor below the corresponding Tier 1 EALs can be assumed to not pose a significant vapor intrusion ...
 
...below the corresponding Tier 1 EALs can be assumed to not pose a significant vapor intrusion threat. If multiple lines of evidence such as those noted above indicate ...
 
...or remedial actions will be warranted. This will typically include the removal of vapor intrusion pathways for existing buildings (e.g., sealing of cracks and gaps in floors, etc.) ...
 
...gaps in floors, etc.) and remediation of contamination in the source area to reduce soil vapor levels to below levels of potential concern. An evaluation of the adequacy of the building ...
 
... and Assessment Model (USEPA 2008d). A detailed review of site-specific vapor intrusion risks can also be carried out if desired and can include the preparation of site-specific ...
 
...desired and can include the preparation of site-specific human health risk assessments, vapor intrusion models and alternative action levels. This level of effort is unlikely to be necessary ...
 
...small sites, however. A detailed discussion of source area remediation and vapor mitigation is beyond the scope of this section but will be included in future updates to the ...
 
...soil beneath the floor of a former dry cleaner. Some combination of excavation, soil vapor extraction, in situ injections, or thermal treatment might be required for a site with extensive ...
 
...In some cases the installation of a subslab ventilation system could be required. A vapor mitigation system for a new structure might include one or more of the following components ...
 
...with wind-activated turbine vents and option for blowers, etc.); and Permanent soil vapor monitoring points through slab and within collection system. Passive ...
 
...to address methane hazards or the buildup of very high levels of solvent or petroleum vapors beneath the slab. Monitoring points within the slab and collection system can be used to evaluate ...
 
... flow in risers, and to support proposals to cease mitigation effects due to a reduced vapor intrusion risk. ...
 

7.10 Documentation of Soil Vapor or Indoor Air Sampling
... ' 7.15 DOCUMENTATION OF SOIL VAPOR OR INDOOR AIR SAMPLING A soil vapor or indoor air investigation report should be ...
 
...OR INDOOR AIR SAMPLING A soil vapor or indoor air investigation report should be submitted to the HEER Office for review following ...
 
...for Investigation Reports is included in Section 18. The submittal of a workplan for soil vapor and/or indoor air investigations is also strongly encouraged. The soil ...
 
...indoor air investigations is also strongly encouraged. The soil vapor or indoor air investigation report should include a thorough description of all field operations, ...
 
...or laboratory analytical flags) and an analysis and interpretation of the data. All soil vapor or indoor air investigation reports should include a site plan map identifying soil vapor or ...
 
...or indoor air investigation reports should include a site plan map identifying soil vapor or indoor air sampling locations. The relative location of soil and groundwater contamination ...
 
...proposed future buildings should also be depicted on the figures. Field activities during vapor point installation and sample collection should be fully documented in the final investigation ...
 
... should be fully documented in the final investigation report. For sites where soil vapor or indoor air samples are collected from permanent probes, the probe construction details should ...
 
... should also be included in the investigation report. The soil vapor or indoor air analytical data should be summarized and presented on a table that facilitates ...
 

9.4 Methane
... Methane Monitoring Conduit Seals and Utility Trench Dams Vapor Mitigation Methane Monitoring Conduit Seals ...
 
... Methane Monitoring Conduit Seals and Utility Trench Dams Vapor Mitigation 0 - ...
 
... Methane Monitoring Conduit Seals and Utility Trench Dams Vapor Mitigation 100 ...
 
...of buildings with cracked floors, gaps around utility penetrations in the floor or other vapor entry routes could also pose potential hazards. Figure 9-1 presents a ...
 
...and mitigation actions for site where high levels of methane are detected in soil vapors (Geosyntec 2011). Final monitoring and mitigation actions for potential ...
 
...(CalEPA 2005b). Be aware that high levels of light-end (C5-C12), petroleum vapors can cause false, elevated readings of methane in vapor samples using a standard, landfill ...
 
...can cause false, elevated readings of methane in vapor samples using a standard, landfill gas analyzer. The use of a carbon trap is recommended when ...
 

Appendix 4-A1 Volatile Chemicals Requiring Field Preservation Of Soil Sample Increments
...   2Vapor Pressure Henry's Law Constant (H) ...
 
...if H > 0.00001), S - solid, L - liquid, G - gas). Vapor Pressures from National Library of Medicine TOXNET or ChemID databases. ...
 

Appendix 4-A1 Volatile Chemicals Requiring Field Preservation Of Soil Sample Increments
...   2Vapor Pressure Henry's Law Constant (H) ...
 
...if H > 0.00001), S - solid, L - liquid, G - gas). Vapor Pressures from National Library of Medicine TOXNET or ChemID databases. ...
 

Appendix 4-A2 Volatile Chemicals Requiring Field Preservation Of Soil Sample Increments
...   2VaporPressure Henry's Law Constant (H) ...
 
...if H >0.00001), S - solid, L - liquid, G - gas). Vapor Pressures from National Library of Medicine TOXNET or ChemID databases. ...
 

13.6 Ecological Risk assessements
... 1997a) Assessing the Significance of Subsurface Contaminant Vapor Migration to Enclosed Spaces (Johnson et. al, 1998) Supplemental Guidance for Developing ...
 

9.6 Methamphetamine Laboratory Cleanup
... Flammable Toxic Vapors Explosive ...
 
...   Burns, toxic vapors Phosphine Gas ...
 

5.10 Investigation Derived Waste
... Pour onto ground in area where samples were collected to allow infiltration or evaporation; Transport to a HDOH-permitted off-site treatment/disposal facility. ...
 

8.2 Data Quality Control and Documentation
...8.4.2 and 8.4.5). Some PIDs can be used to measure both total VOCs in vapors emitted from soil as well as concentrations of a limited number of individual compounds (e.g., ...
 

8.4 Field Screening Methods for Selected Contaminants and Media
...soil tested; Potential under reporting of TPH concentration due to evaporation of volatile petroleum hydrocarbon mixtures such as gasoline during test procedure. ...
 
... an ultraviolet fluorescence spectrophotometer. The fluorometer uses a mercury vapor lamp as its light source. Petroleum compounds in soil sample are mixed and extracted ...
 
...as sample containers (e.g., Associated Bag Company Item #183-52) in order to minimize vapor loss during the recommended fifteen- minute equilibration period. ...
 
...and JP-8) or when the fuel type is unknown. This corresponds to anticipated lower vapor emissions from soils containing 100 mg/kg TPHd in comparison to gasoline-contaminated soils, ...
 
... light-end aromatics and aliphatic compounds in these fuels (assumed 10% of gasoline vapor emissions; see also HDOH 2012). Consultants report that PID readings below 10ppmv are unreliable ...
 
...volatile aromatic compounds. PIDs are not good indicators of total TPH levels in soil vapors because they do not respond well to aliphatic volatile compounds, which dominate vapors ...
 
...because they do not respond well to aliphatic volatile compounds, which dominate vapors from petroleum fuels (refer to Section 7 and Section 9). Advantages: ...
 
...than for an equivalent concentration of gasoline due to low, aromatic content of vapors. Requires use of a container that minimizes loss of volatile chemicals ...
 

8.5 Field Screening With Cone Penetrometer and Sensors/Probes
...or pneumatic hammer to drive the MIP to the depth of interest to collect samples of vaporized compounds. The probe captures the vapor sample, and a carrier gas transports the sample ...
 
...compounds. The probe captures the vapor sample, and a carrier gas transports the sample to the surface for analysis by a variety ...
 
...dry electrolytic conductivity [DELCD] detectors) that establish the presence of VOC vapor, dissolved phase LNAPL, or DNAPL in soil. These detectors may be deployed singly or in ...
 

8.6 Field Screening Equipment to Support Health and Safety Programs
...industrial hygienist. Weather conditions such as extreme heat or cold, humidity (water vapor), exposure to rain or other spilled liquids, and electromagnetic radiation can all affect the ...
 
...typically uses a platinum filament, which is heated by burning the combustible gas or vapor. The increase in heat is measured and reported as a percent of the lower explosive limit ...
 
... Advantages Measures the presence of combustible gases/vapors Range : 0 � 100 % of LEL (units are % of the LEL or ppm depending on ...
 
... in hydrogen flame Can detect compounds with high ionization energy vapors (such as methane). Limitations Can flame out ...
 
... instrument response Does not detect methane and other vapors with high ionization energy Multiple sensitivities (multiple electron ...