Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:1850:p55
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 1850 (pt 55/117)
Character Range: 500098–502988

permanent probes. The probe installation method used should be determined based on site-specific factors such as access and environmental conditions (for example, soil texture or moisture conditions that may limit the use of very narrow tubing).

A log of soil types encountered during drilling should be documented. To assist in the assessment, a soil core may also be recovered and subsampled to determine organic carbon and soil parameters (for example, bulk density, porosity and soil moisture content) at the depths of the sampling ports, and for analysis of the soil for the chemicals of concern.

Correct sealing of the installations is essential, especially in low permeability soils. Separate installations rather than multi-level samplers may be necessary in low permeability soils to ensure a good seal is able to be achieved or where the upper sample is less than 1 m below the surface.

Sampling of permanent probes and multi-level samplers can be carried out using a range of sampling methods. Typically, permanent probes should be left for a minimum of 24 to 48 hours to equilibrate prior to sampling (DTSC 2009; NYSDOH 2006), depending on the installation method and the site conditions.

9.4.2.3         Online VOC and oxygen probes
Near-continuous measurement of total vapour (or VOCs) and oxygen concentrations is possible using online VOC and oxygen probes (Patterson & Davis 2008; Patterson et al. 1999, 2000). These can be buried at multiple depths to give near-continuous measurements of total vapour and oxygen concentrations for extended periods (months to years). Apart from providing vapour and oxygen depth profiles, the detailed information derived from these probes allows seasonal trends in vapour fluxes and other parameters such as degradation rates to be assessed.
Online VOC probes (at the time of drafting), do not directly monitor individual compounds such as benzene, but can be subsampled to obtain a gas sample which can then be analysed by conventional means for component VOC and major gas concentrations.

9.4.2.4         Factors for consideration when undertaking active soil vapour sampling
The following factors require consideration in the design and implementation of an active soil vapour sampling program:
    * Probe integrity/seal — soil vapour probes (temporary and permanent) should be installed in a manner that ensures that ambient air is not drawn into the sampling system and that a representative soil vapour sample can be collected. This may require an additional seal around the probe using bentonite slurry and leak testing, even for temporary installations. An effective seal is particularly important in low permeability soils and for shallow probes or sub-slab probes. A number of tracer methods are available to test seal integrity  see API (2005) and ITRC (2007b).
    * Tubing type — the tubing type should be selected to