Proposed Excess Soil…

Proposed Excess Soil Management Plan: The proposed Regulation goes into great detail describing what must be included in an ESMP, including the number of soil samples to be analysed and from where they are to be taken but, as with the current version of O. Reg 153/04, there remains a fatal disconnect between the sample collected in the field and the analytical result provided by the laboratory. Both Regulations call for "representative samples" to be submitted to the laboratory but neither gives any guidance on how to ensure the field samples are indeed representative. Given the highly heterogeneous nature of contaminants in soils---especially particulate contaminants such as metals, PAH's, etc., the current practice of sending a small jar of soil to the laboratory for analysis cannot, in too many cases, produce a meaningful result because it is not possible for the 100-150 grams of soil sent to the laboratory to be representative of the several tons (millions of grams) of soil from which the sample was collected. In other words, the lab sample is far too small to be representative. This is bad enough but the problem is worsened by orders of magnitude at the laboratory because only 1-2 grams of sample from the bottle submitted actually gets analysed!

Thus, if a site condition standard (SCS) for a soil is <5 ppm (mg/Kg), for example cadmium, benzo-a-pyrene, etc., then a million soil particles will contain <5 particles of contaminant and the lab would have to analyse several million soil particles from the bottle to have any hope of producing the correct result. However, the bottle usually contains <250,000 soil particles (depending on the type of soil) which is insufficient to be representative of the millions of grams in the field. Greatly compounding this, the 1-2 gram sample actually analysed contains only a few thousand particles so the lab result typically reports a "non-detect" result (no contaminant particles present). Of course, if one or more particles of contaminant do show up in the lab sample, the lab result will indicate a concentration far above the SCS and the QP will have to ignore the glaring statistical impossibilities involved and write this up as an exccedence requiring further investigation and cleanup.

Until this issue is addressed, the proposed Regulation sits on the same shaky ground that the current version of O. Reg. 153/04 occupies, namely, the lab results used by the QP to define the soil and groundwater quality are highly suspect due to the inability of the small lab samples analysed to be even approximately representative of the field conditions. Despite the labs' supreme efforts to control the quality of their analytical results, QP's will continue to experience the following issues in phase 2 ESA investigations, cleanups and the proposed ESMPs:

1. Lab results that show non-detect levels of contaminants in soils may actually exceed the SCS because the SCS is far too low for the sample submitted to contain any contaminant and to be representative of the surrounding soil. Low SCSs require much larger samples to be representative because there very few contaminant particles in the soil, Of course, no one will find out until someone else happens to submit a sample which far exceeds the SCS because a single particle of contaminant managed to get included in the 1-2 grams analysed.

2. Attempts to characterise an excess soil using the proposed sampling protocols in the ESMP lead to frustrating "odd-ball" exceedences of an allowable limit in a series of samples submitted for analysis which otherwise meet the SCS. These will be written up as "hot-spots" when in fact they are simply the unavoidable result of analysing small, unrepresentative samples.

3. Quality control duplicate samples with an unacceptable relative % difference (RPD) between them. This issue may be much worse than realised because both sample and duplicate have a far higher chance of not including any contaminant particles where the SCS is in the low ppm range and so both results show the low bias typical of this type of situation. Also, there is no guidance on what an acceptable RPD should be.

RECOMMENDATIONS

1. The proposed sampling protocols need to be revised to address the statistical issues associated with collecting representative samples of soil from the field. Guidance must be given as to how to collect a representative sample so that the lab result is meaningful and this should include a consideration of the sample size based on the SCS.

2. Averaging of the results of multiple analyses of field samples should be allowed along the lines of the "Integrated Sampling Methodology" (ISM) currently in use in the U.S.A.

3. Given that current laboratory analytical methods cannot handle more than 1-2 grams of soil per sample, emphasis should be placed on developing leachate SCS rather than soil SCS since leach-testing can employ much larger samples and produce a leachate that current lab methods can easily handle.

[Original Comment ID: 209553]