Now that the majority of utility lines have been relocated,
crews have begun the first steps towards surcharging the existing unsuitable
subsoil. “Surcharging” is required on this project due to the unsuitable
nature of the underlying soils found along the majority of the project.
The existing subsoil consist of soft clays and a large amount of organic
matter. If these soils are not properly surcharged, long term settlement
of the new roadway and utility lines could be at stake. Surcharging of
these soils involves undercutting the first five feet of material, placing
geotextile fabric along the bottom of the trench and then backfilling with
suitable soils. Next wick drains will be installed approximately 40’
vertically into the ground. Wick drains are not always required to
accomplish surcharging of unsuitable underlying soils, but will accelerate the
surcharging process. The addition of wick drains with surcharging will
allow the process to occur in six months versus potentially a year and a half
or two years. Once wick drains are installed, then suitable soils will
continue to be built up on the surface (above proposed final grades). The
combination of wick drains and the weight of soil over the unsuitable subsoil
will force moisture out of the underlying soils, consolidating this unsuitable
material. This surcharging affect will result in predicted settlement
over a six month period. This settlement over a six month period will
prevent the underlying unsuitable soils from settling gradually over a long
period of time. Surcharging efforts have begun along the new alignment of
General McIntosh Boulevard as well as along the south side of President Street
closest to town. These efforts will continue over the next few
months.
A second crew continues to make progress on the south side
of President Street by installing the new 8” water main, manholes, valves, and
fire hydrants. Once these lines are installed, this crew will mobilize to
General McIntosh and Randolph Street to continue new utility line installation
of water, sewer, and storm drainage lines in this location.
As mentioned in previous posts, a third crew continues to
work along the south side of President Street (either side of the Truman
Parkway) installing steel casing beneath the railroad tracks found in this area
of the project. Installation of these steel casing will allow utility
crews to run future water, sewer, and gas mains beneath these tracks without
damaging the tracks or interruption of train operations along the tracks.
An additional fourth crew will be mobilizing to the site
this week to begin installation of water and sewer utility lines on the far
east end of the project (along the south side of President St., both sides of
Truman Parkway).
Rain during previous weeks has delayed the paving
contractor, but he hopes to be back on schedule this week to pave Randolph
Street (just south of President Street).
