Department of Health Seal

TGM for the Implementation of the Hawai'i State Contingency Plan
Subsection 5.5
COLLECTION OF SAMPLES FROM STOCKPILES

5.5 COLLECTION OF SAMPLES FROM STOCKPILES

The designation of DUs for stockpiles is discussed in Subsection 3.4.6. Sampling strategies and methods specific to stockpiles are discussed in the HEER Office document Guidance for the Evaluation of Imported and Exported Fill Material (See Appendix 3-A; HDOH, 2017d). A summary is provided below.

It is important to allow equal access to all soil with a stockpile DU for the collection of increments. Increments collected from only the exposed surface of a stockpile, for example, might not be representative of deeper soil. When space is available, the stockpile should be flattened to a thickness of three feet or less to allow equal access to all soil in the pile. Increments are then collected from the top, middle, and bottom of the pile in a systematic random fashion (Figure 5-33).

Figure 5-33. Collection of Increments and Multi Increment Samples from a Flattened Stockpile

Increments are collected alternately from top, middle, and bottom of flattened DU in order to collect a representative bulk Multi Increment sample.

Another option is to collect increments as the stockpile is being formed (Figure 5-34). For example, increments could be collected from front-end loader buckets at appropriate intervals of soil volumes as the soil is being excavated or moved. Increments could also be collected as piles are formed at the end of a conveyor belt, or when stockpiles are being moved from one location to another. This allows equal access to each portion of the pile as it is constructed, avoids the need to reconstruct a stockpile, and saves space required to flatten a stockpile for sampling. The collection of soil samples during these activities can interfere with the operation of heavy equipment, however, and requires close coordination with the other parties.

Figure 5-34. Examples of Opportunities to Collect Increments and Bulk Multi Increment Samples during Stockpile Formation or Movement

A third option is to progressively characterize small volumes of soil in an unflattened stockpile as needed (Figure 5-35). Increments could be collected from the surface and shallow depths within the exposed face of the stockpile. Soil represented by the resulting, bulk Multi Increment sample can be cleared for reuse or disposed as appropriate. Replicates could be collected as described, but from alternate systematic random locations from the surface and shallow depths within the exposed face of the stockpile to assess the precision of the sample collection method.

Figure 5-35. Progressive Testing of DUs from an Unflattened Stockpile

Increments collected from the surface and shallow depths within the exposed face to prepare the bulk Multi Increment sample.