A few months ago, we published the blog, “Why is it Important to Flush Underground Fire Service Mains?”, where we reviewed some of the many interesting objects (like hard hats, safety glasses, and rocks) that we have seen make their way through underground water piping throughout the years that we have provided underground flushing services to our clients. We had the idea to put together the blog after a large 2 x 4 had been flushed through underground piping at a client’s job site in California and one of our fire protection engineers was able to snap a picture of it. If you didn’t get the chance to read the blog, make sure and check it out, using the link above. Not only can you see the picture of the 2 x 4, but the post also includes a short video of an underground flushing in action. It doesn’t show any unusual objects coming out, but it gives you an idea of the process in action.

More recently, another one of our fire protection engineers spent two days witnessing the flushing of several sections of underground piping for a one-million square foot distribution center in Robbinsville, New Jersey. This engineer was also able to snap a photo during the process.  While there were no real surprises during the first day, just some gravel and dirt, the second day was a little bit more exciting.

During the flushing of one of the riser lead-ins, our engineer heard a loud clank in the flushing pipe. He then saw the sack that was placed over the outlet to catch debris jump! When the water stopped flowing, he pulled out a huge chunk of concrete that was at least 8-inches long (seen in the picture above) from the sack.  The hardhat did NOT come out of the pipe, but is being used to show perspective of just how large this chunk of concrete was!

The concrete chunk managed to damage the butterfly valve on the flushing pipe on its way out. And, for this particular fire protection engineer, the concrete chunk is the largest object that he has seen come out of an underground pipe in his over 30 year-career. The concrete likely ended up in the pipe when the thrust blocks were poured. When underground piping is installed, it is open to a variety of objects, like this, that find their way into the pipe. That’s why underground flushing is so important. If objects are left in the piping, they can create serious problems for fire protection systems by obstructing the flow of water and reducing the performance characteristics of the systems.

Our fire protection engineer is keeping this photo on his desktop so that it’s readily available any time someone asks him why it’s necessary to go through the underground flushing process!

By Jeff Harrington, CEO and Founder of Harrington Group, Inc.