SS9301-CS 930503 9). 697
xa , 76097-0697
May 3, 1993 9ax [$,?/ z95-~zp$
Kenko Brothers
16415 Addison Road
Suite 308
Dallas, Texas 75248
City of Coppell - Grapevine Creek Sewer Trunk Main
Branch I & II
Tunnel and Casing With PVC Carrier
For the portion that is to be installed in casing pipe,
we propose using 48" tunnel liner plate. Then install a rail
system grouted in place in the bottom of the tunnel, install
the pipe on wood block skids in the lower portion of the
tunnel rather than in the center. This will allow room for
installing wood blocks between the top of the PVC carrier
pipe and the top of the tunnel to line and grade. We propose
to fill the annular space between the liner and the carrier
pipe with pea gravel.
The use of grout around ultra rib pipe is apt to cause
deflection because the ribs that provide stiffness also
provides a conductor factor with the heat of hydration that
softens the ribs extensively because the grout completely
surrounds the ribs, absorbing the heat from both sides of the
ribs.
We find that pea gravel gives the better probability of
getting a complete fill without voids than sand because of
condensation or wet conditions within the tunnel. Sometimes
sand tends to stick to the pipe support blocking, the wall of
the tunnel or carrier pipe and begins to cake, build up and
bridge off which increases the possibility of voids in the
annular space back fill. The inherent damp or wet conditions
we find doesn't affect the installation of pea gravel like it
does the sand. Also the pea gravel does not shrink like sand
that is installed dry and later becomes wet.
After the carrier pipe is installed, the blocking is
installed between the top of the pipe and tunnel, we will be
able to get a snug fit which cannot, due to pipe tolerances
Coppell Submittal
May 3, 1993
Page Two
and slack space needed for the pipe to slide into the casing,
be achieved if spacers are installed outside the casing and
slid into place. Ample room to do a better job of blocking
will be provided by lowering the carrier pipe to the lower
portion of the casing.
The liner plates will be installed as the material is
hand mined. L Line and grade will be maintained by the use of
a laser beam. After the liner is installed the rail and
grout invert will be installed to precise line and grade and
the pipe installed and well secured by the wood blocking. The
pea gravel will be installed by the use of a gunite machine
blowing the gravel through a PVC pipe that is installed along
the top portion of the tunnel or the space between the top of
the pipe and the tunnel support system. The blow pipe will
be pulled toward the gunite machine as the void is being
filled, no more distance at any time than that which will
provide a void free backfill.
Submitted By:~ .
Charlie Griffi(~nF
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