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SS9301-SP 930503 (4) _Sout and U ont a t ng, ©. 76o97-o69 May 3, 1993 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. Charlie Gri~f{~n~/ CG:mlg C ,PE~ GeAV£L ~ 2. FLA/~GF_. ,~i~ PLE r~ oo~1 PF...~, g