Is our only objective to obtain a partial closure on the O-1 pond by removing contaminated soil?  If so, soil borings may not be necessary.

If an objective is also to characterize underlying rock strata at the same time as “closing” the O-1 pond soils, then are 25 borings really needed?

Completing up to 25 soil borings to approximately 27 feet below ground surface (bgs) in a radiating pattern out from the historic O-1 pond (Figure 1).

Completing two sets of borings and collecting and analyzing 3 soil samples from each boring.  If contamination is found in any sample, then additional borings will be completed beyond the contaminated borings.

Continuing this process until extent is defined or until 25 soil borings are completed.

Overexcavating all soil from the O-1 pond historic boundary until no signs of contamination are detected.

Collecting and analyzing sidewall samples from the excavated area.  If contamination is found in any sample, then additional excavation will be completed and additional sidewall samples will be collected.

Continuing this process until all contaminated soils are removed.

Completing up to 25 soil borings to approximately 27 feet below ground surface (bgs), set out in 10 foot by 10 foot grids (Figure 2).

Creating 10 ft by 10 ft grids, starting in the historic O-1 pond area, completing one boring for each grid, and collecting and analyzing 3 soil samples from each boring.  If contamination is found in any sample, then additional grids and borings will be completed beyond the contaminated boring.

Continuing this process until extent is defined or until 25 soil borings are completed.