Tapping Lined Pipe
Agencies line pipe for 2 main reasons, first the pipe is in bad shape structurally and secondly it has I & I issues. Most commonly the pipes in question are Concrete or Clay and are 50 years or older. Pipe lining will greatly extend the life of the mainline but it does little to solve the I & I problems. Studies have shown 50% of the I&I problems are due to the laterals. For many years Lining companies would re-establish the lateral lines by robotically cutting holes in the liner where the laterals connect. This does not solve the lateral leaking issue and both ground water and roots can still enter the mainline through breaks by traveling between the liner and the host pipe and pouring in the cored hole.
If the host pipe is 50+ years old then the lateral line is also. 50 years ago lateral pipes that were available were of much lesser quality than the mainline options. We see concrete drain tile, galvanized, Orangeburg, cast iron, and many other forms of pipe no longer in use. The Liner companies would like to see you line these old laterals and seal the hole using “top hats “.
We think you need to ask the questions “are the laterals worth ignoring or having them lined”? We feel in most cases they should be replaced. New PVC lateral pipes will provide a much longer leak proof life.
We have two methods to re-establish laterals. First, we tap the host pipe with a Tee designed for that pipe and diameter. Our preferred method is to tap the liner as the drawing demonstrates.
4 mil liner in concrete pipe, Medford, Oregon (left), 4" Inserta Tee installed in 6 mil Insituform liner (right)