Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:1850:p21
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 1850 (pt 21/117)
Character Range: 404497–407423

been measured to calibrate the LIF response to the specific NAPL contamination present at the site. The LIF data should also be validated with soil and groundwater sampling to determine concentrations of specific contaminants throughout the investigation area.

As for MIP, the LIF is combined with an electrical conductivity sensor to interpret lithology and is used in a similar reactive sampling approach. Similarly, with multiple LIF locations and the use of data interpolation and visualisation software, LIF data can enable a 3-D depiction of NAPL source areas in both the unsaturated (vadose) and saturated zones.

    7.2.6          Soil vapour surveys
Source: NJDEP (2005a)
Soil vapour surveys may be used to screen sites for VOC and SVOC contamination source areas in the vadose zone and to delineate the extent of contamination. Soil vapour sampling, when applied appropriately, can be used as a screening procedure to assist in locating soil sampling and monitoring well locations.

There are two basic types of soil vapour surveys performed as part of site assessments. The first type is an active soil vapour survey where a volume of soil is pumped out of the vadose zone into a sample container or directly into an analyser. The second type is the passive soil vapour survey where a sorbent material is buried in the vadose zone so that contaminant vapours can be selectively absorbed over time using the ambient flow of vapours through the subsurface. The latter is particularly applicable to low permeability soils where active methods are less effective.

Further information on soil vapour sampling is presented in Section 9.

    7.2.7          Ground penetrating radar
Ground penetrating radar is the most commonly used of the geophysical methods and is typically conducted by rolling a radar unit across the site in a grid pattern and recording and processing the data collected to provide a two-dimensional or three–dimensional image of the surveyed area. Metal objects or near–surface features (such as pipes or utilities) can cause noise on the measured signal; if the location of these features is known, their effect can be minimised in the data processing stage. In homogeneous soil profiles, ground penetrating radar surveys may assist in defining the lateral and vertical extent of NAPL plumes in shallow soil or groundwater—see Clements et al. (2009).

7.3              Field description of soils
Accurate documentation and careful consideration of field observations is essential as this can greatly improve understanding of the variability of contaminant distribution across a site.

All boreholes (including groundwater monitoring wells) and test pits should be logged in accordance with AS 1726-1993 and the presence of strata, moisture, seeps or water-bearing zones, elevation of the water level/hydraulic head, imported fill and odorous or stained materials carefully noted. These logs are