Thursday, January 20, 2011

Around the Sound: Rayonier Mill investigations continue

By Connie Groven, project manager

Over the last few weeks, you may have noticed heavy equipment and activity on the Rayonier property again. What is going on now?

Here are some photos of the test pit process…
1. An excavator digs a pit and sorts the material by layers.

2. The pits allow sampling and observation of the layers of material.

3. The side walls of shallow pits are sampled from inside the pit.

4. Samples from deep pits are collected from the bucket.

5. If visibly contaminated soil is found, it is separated...

6. ...and placed in a container for removal.

Questions remain about some areas of the Rayonier property. Project managers, engineers, and archeologists need to better understand what is below the ground surface and where contamination is before Rayonier can plan cleanup of the Study Area. Rayonier is digging pits in certain areas of the property where more information is needed.

Targeted test pits

An excavator digs the pits in selected areas, stopping to allow sampling at different depths. A field geologist or engineer keeps a written record of the subsurface conditions in the test pits. On the Rayonier property, an archeologist also watches for anything of historical significance. Soils removed from the pit are separated by layers so they can be replaced in the order removed.

Taking a sample

Samples are collected from each pit at several depths. Samples of the soil are scraped from the side walls of the pit, placed into clean glass jars, labeled and sent to the lab. When the pit is shallow, the sampler can collect the samples while standing in the pit. When the pit is deeper, it would not be safe to enter the pit, so the sample must be collected from the bucket of the excavator. The excavator bucket and all the tools used are cleaned between pits.

Some types of contamination cannot be seen and must be determined by the results from the lab. Other types of contamination leave a visible stain on the soil, produce a sheen on water, or can be detected by a photoionization detector (PID). If work crews saw or detected contamination, they separated the material and placed it in a container to be removed from the property.

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