Topsoil Layer
A 2 inch thick topsoil layer was observed at test boring B-1. The topsoil layer consists of dark
brown to grey, dry, loose, silt and very fine sand with abundant roots. A trace amount of fine
gravel was noted.
Fill Layer
A fill layer associated with the roadway embankment construction was encountered at the
location of soil boring B-1. The thickness of the fill layer was determined to be approximately
3.0 feet. The fill layer consisted of brown, loose to medium dense, fine sand, little silt, and trace
fine angular gravel. The Standard Penetration Test results in the fill layer at B-1 ranged from 8
to 19 blows per 12 inch penetration of a standard split-spoon indicating loose to medium dense
relative density conditions.
Original Topsoil Layer
What appears to be the naturally occurring topsoil layer was encountered at a depth of 3.0 feet
below ground surface. The natural topsoil layer is approximately 3 inches thick and consists of
dark brown to gray, loose, organic silt. No roots or plant debris were observed.
Subsoil Layer
The original topsoil layer is underlain by a silty subsoil layer. The subsoil layer is approximately
0.75 feet thick and consists of orange-brown, rusty-brown, loose to medium dense, fine sand and
silt.
Sand and Gravel Layer
A sand and gravel layer, encountered at test boring B-1, was approximately 4.5 feet thick and
directly underlies the subsoil and original topsoil layers described above. The sand and gravel
layer consists of brown, very dense, fine to coarse sand and fine to medium sub-rounded gravel.
Broken rock fragments, perhaps from boulders, were also noted. Angular rock fragments were
observed near the bedrock surface. The Standard Penetration Test values in the sand and gravel
layer at B-1 was 60 blows per 12” of spoon penetration indicating dense to very dense relative
density conditions.
Auger Refusal
Auger refusals were encountered at test boring B-1 and test probe P-1. The depths to auger
refusal at B-1 and P-1 were both at approximately 8.5 feet below ground surface. The auger
refusals are interpreted to be on the bedrock surface. Numerous bedrock outcroppings were
observed on the west side of Daniel Webster Highway.
The following table summarizes the subsurface conditions encountered:
