SOIL MANAGEMENT
the project objectives, then the perimeter DU samples do not need to be analyzed at all. This technique can also be valu- able when characterizing soil for disposal, as the landfill may require additional analyses to ensure contaminants won’t leach into the landfill over time (typically referred to as Toxicity Characteristic Leaching Procedure – TCLP – analysis).
Of course, staggering the analysis like this can extend the time required to receive final results by a week or more. When there is ample time built into the project, significant savings can be achieved by holding dependent analyses in conjunction with using standard turnaround times.
Planning can be the difference between spending twice as much in analytical fees for results in three to five days versus getting the same results for half the price tag in three to five weeks, using the contingent analysis approach with standard laboratory turnaround times.
fees. Furthermore, all samples will need to be analyzed for all potential contaminants as quickly as possible, thus compound- ing the analytical fees at a premium rate.
In this example, we’re already at two weeks or more down the drain to develop a sampling approach, collect the samples, and get results – all at rush premiums for the absolute fast- est answers possible. For a small project. This hypothetical schedule also assumes the regulatory agency doesn’t need to be involved and the drillers are readily available; something that is by no means guaranteed.
With forethought, the same information can be obtained within two to three weeks at a significantly lower cost, pro- vided contamination is not detected in the primary sample. Note, if contamination is detected in the primary sample, the schedule for results will be extended by at least another week.
If results come back indicating contamination is present at concentrations above the applicable action levels, then regula- tory involvement becomes necessary, as does a lot of additional planning (Figure 1). Iterative sampling may also be required depending on the project objectives. Additional worker protec- tions may be required. If the soil is classified as a hazardous waste, arrangements need to be made for disposal at a per- mitted landfill on the continental US. None of this supports a rush project. It is much easier on both project timelines and budgets to consider – and plan for – these potential scenarios before mobilizing to break ground.
What if I Haven’t Accounted for Soil in the Planning Phase?
Fortunately, there are some workarounds for those clients who did not have the knowledge or foresight to plan for poten- tial soil issues, or who have encountered unexpected conditions despite their due diligence. Real time monitoring in the field during soil disturbance can be effective for some contaminants. Workers may need to wear respirators and protective coveralls until further characterization is performed, possibly to include negative exposure assessment via air monitoring. If soil is grossly contaminated or cannot be reused on-site, it can be stockpiled and sampled for disposal, provided there is room on the site. These alternative methods are not ideal, but they are sometimes necessary.
The Takeaway
Soil management, if performed with purposeful forethought and planning, can be incorporated into construction projects to minimize schedule impacts and costs. How is this best accomplished?
Figure 3. Example of vertical DU layers, with a shallow spill DU and two underlying perimeter DUs.
Example
Consider an area that has been divided into three verti- cal DU layers of varying depths to evaluate how deep the contamination extends (Figure 3). Based on the MI sampling technique, this will result in three samples (one shallow, one at mid-depth, and one deeper). If the decision from this sam- pling and analysis is holding up construction and an answer is needed yesterday, there is still going to be a three to five day wait regardless of the premium for rushed laboratory
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1. Engage an environmental consultant as early as pos- sible.
2. Identify the key soil management issues relative to the project.
3. Define the soil management objectives. 4. Account for potentially contaminated soil.
5. Incorporate these considerations into the schedule and budget.
Oct.Nov.Dec 2022 • TPG 33
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