Earlier in the year, I witnessed the installation of 40 LF of Polycast 600. Polycast 600 is a pre-sloped polymer concrete product manufactured by Hubbell. It is similar to many commercial grade products out on the market except that it is measured in feet instead of meters.
The 600 Series in question used galvanized steel slotted grates and Polyguard steel channel protectors. Channel protector are strips of galvanized steel that help prevent premature edge deterioration of the polymer channel. For this particular installation, the channel protector and grates were both left in place. The grates were later protected with plastic sheeting prior to pouring concrete.
The job was a new equipment storage facility located in the Pocono Mountains of Pennsylvania within earshot of the Pocono Raceway. Contractors planned to pour the overall floor of the facility at the same time as the drain in order to pitch the floor toward the drain.
The site was already installed with gravel so the excavator roughed out a trench to install the drain. I noticed that nobody had compacted the gravel, which will probably cause a problem in the future. The gravel base for trench drain and all concrete floor projects needs to be compacted. This floor has an excellent chance of developing voids underneath the concrete in the future.
The installer determined where to place the trench drain and set a level line. Then, the team cleared debris from the trench to assure that the channels could be set without obstructions.
Next, they set the channels alongside the trench in the order they would be installed. When installing trench drain, the deepest channel (highest channel number) connects to the discharge invert. Here, discharge water exited the end of the trench drain into a 4″ PVC pipe. Contractors drilled through the foundation of the building for this pipe to exit; later, they tied it into a drain pipe that took the water to a sewer.
Installation started with the deepest channel first, then proceeded upstream. Installers worked their way backward to the shallow invert (smallest channel number) at the beginning of the drain’s flow path.
The channels were connected to each other with an installation bracket and connected to ½” rebar (#4). This particular installation bracket is patented and used exclusively with the Polycast system. Bolts from the installation chair fit into the “dimples” of adjoining channels to hold the channel tight. The bolts can adjust in or out to help align the channels left or right. The chair can also be adjusted up or down on the rebar to keep the top of the drain (grate) on level. It makes installation easy.
Once the first few channels were put into place, the remainder of the installation went smoothly. The channels seemed to fall into the proper place when the installation chair was properly used. In the end, we had a 40 foot length of polymer concrete trench drain suspended in air and ready to be set in concrete.