City of Miami – Biscayne Island
Biscayne Island is the gateway to South Beach Miami; a place of multimillion dollar homes where many famous people have owned homes throughout the history of the island. There is an existing storm drain system that takes the rain water from the small streets out to Biscayne Bay. These 24 inch diameter clay pipes were installed back in the 1930’s. Many of these pipes have become broken and cracked over the years, making the storm sewer system inefficient. Most of the streets on the island would become flooded during a rain storm. The engineers of Miami were scratching their heads as to how to rehabilitate these pipes. They called US Sewer & Drain to help figure out the problem.
When US Sewer sat down with the engineers of Miami to discuss the options on how to rehabilitate these pipes, there were many obstacles to consider. Many of these large pipes run from the street, through the home owners’ yards and out to the bay. Over the years many of the residents have built overtop of these pipes with ornate outside decks, gardens, driveways additions, etc, so conventional dig and replace methods were out of the question.
The idea of “Cured-In-Place” pipelining was introduced. However, because the bay is home to the world famous “Biscayne Bay Aquatic Reserve”, the styrene that is present during the pipelining process was a concern to the safety of the Manatee and other wildlife.
The idea of “Pipe Bursting” was introduced, a method which splits the existing pipe in half while simultaneously pulling a new High Density Polyethylene pipe in its place. The Miami engineers seemed to really like this idea. It was non-intrusive and safe for the environment. However, from a logistical standpoint, it would be easier said than done.
Pipe bursting requires access at both the upstream and downstream openings of the pipe. In this case the upstream portion of the pipe was located in a very narrow street, a street that typically would only allow for a one car lane. An 8 foot x 8 foot hole would be required overtop of the end of the pipe. This hole would take up most of the existing street. A traffic plan would need to be devised in order to execute the job, as well as let traffic in and out of the neighborhood. At the outfall the 24 inch diameter pipe was 8 feet under water. This would mean a platform would need to be devised in the bay in order to launch the new pipe. To add to all of these critical factors the tides would play a key role in this job. Tide charts would need to be referenced.
An elaborate plan was devised to include underwater divers, a 40 foot barge and access pit in the existing street,and a large pipe bursting machine. When the pipe was delivered the US Sewer crew quickly went to work fusing the 24inch diameter piping together. The pipe was then floated out into the bay. Once the pipe was in place the barge was then used to stabilize the pipe and provide a staging area for the divers. A small boat was used to coral the 300 ft long floating piece of pipe while it was pulled into place by the 50 ton pneumatic bursting machine upstream.
This procedure was followed for all six pipe locations on the island. Over all more than 1,800 feet of pipe was rehabilitated with little to no disturbance. Congratulations to the US Sewer & Drain dive team and pipe fitters for another job well done. We would like to thank the City of Miami for the opportunity to perform the work.