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Date: | Tue, 30 Aug 2005 15:33:32 -0400 |
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Kristin,
The plexiglas hypotheis has merit, but only to a certain depth. This material
is expensive and scratches easily, so can only be used in limited situations.
Also, moisture builds up to hard surfaces and viewing would soon be obscured.
Finally, there is the issue of engineered safety beyond a certain depth. This
is why mining engineers design wood shoring and archaeologists use corrugated
steel pipes for safety barriers. Federal and state safety laws usually
require massive shoring at depths greater than five feet. What archaeologists need
is a grant to fund engineering archaeologists to devise safety systems that can
breathe moisture molecules and still be visible for strata viewing while
digging at safe depths. Until that happens, we are back to either wooden shoring
or creating slopes at a ratio of 2:1 to buttress sidewalls. Oh, and in my
experience with safety engineers, they want a key-trench cut at least 36-inches
deep at the toe of the slope to lock it into place. The key-trench could be very
destructive unless excavated by archaeologists. Finally, achieving a 2:1 slope
at four sidewalls would either create a test pit the size of a house
footprint or result in effectively back-filling the pit.
Ron May
Legacy 106, Inc.
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