Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:1850:p53
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 1850 (pt 53/117)
Character Range: 494740–497718

consideration of the investigation objectives and analytical requirements as documented in the SAQP.

More detailed information can be found in Davis et al. (2009a), Baker et al. (2009), API (2005), NJDEP (2005a and 2005b), NYSDOH (2006), and ITRC (2007b, 2007c). Baker et al. (2009) contains discussion on the advantages and disadvantages of various sampling techniques and sampling equipment.

Sufficient sampling should be carried out to ensure that the results are representative of the site conditions and appropriate for assessing the risk to identified receptors.  The following factors should be considered in the design and implementation of a soil vapour sampling program:
    * Location and number of sampling points— the number of locations will depend on the CSM and access considerations. As a minimum for vapour intrusion assessment, samples should be collected above the maximum source concentration near or under a building (located within the 30 m screening distance – refer Section 9.2.1) and at each corner or along each side of the building (if practical).
    * Depths — the depth of samples should be based on the CSM and take into consideration the depth of sub-surface sources, the nature of the contamination and the likely migration pathway(s). In most cases sampling should be undertaken at depths >1 m to avoid transient effects. Where shallow sources are present or where deep samples cannot be obtained, the collection of soil vapour from shallow depths (<1 m) may be appropriate; however, sampling from these depths requires justification. When installing sample equipment at (or using data from) shallow depths, the potential for aerobic degradation and potential transient influences should be considered.
    * Frequency —Multiple sampling events are generally required to characterise and assess vapour risk particularly where (i) the data is close to (compared with the likely variation in soil vapour concentration and the precision and accuracy of the data) or above guideline values, (ii) if samples were collected from shallow depths (<1 m), and/or (iii) seasonal variations in temperature and/or soil moisture and the effects on soil vapour concentrations are not fully understood.

    9.4.2          Active soil vapour sampling
Active soil vapour samples may be taken from probes installed in open ground or recovered via access holes drilled through sealed surfaces such as a driveway or parking area ('near-slab') or beneath building foundations ('sub-slab'). Sampling installations may be permanent, semi-permanent or temporary depending on access and the need to re-sample. The basic sampling approaches for soil vapour sampling include:
    * point samples at specific depths in one or more lateral locations and
    * vertical profiles of samples at two or more depths at one or more lateral locations ('transects').
Additional factors for consideration when designing and implementing an active soil vapour sampling program are