Dobson RdツinツSun Lakesツin Danger of Collapse

From Our 24/7 Emergency Response Team

Dobson RdツinツSun Lakesツin Danger of Collapse

June 16, 2017

By Richard Garlick


There is nothing like getting a 10:30am phone call about an urgent surface street collapse situation in the middle of a major road in Sun Lakes. Honestly, emergency jobs can be an exciting whirlwind. A paving truck had caused an already deteriorating manhole to cave in due to road construction in the area along Dobson Road. Since this manhole was attached to a force main, sewageツbegan pouring out at an alarming rate and was only being managed by four large vactor trucks called in to continuously pump it out. The worst part, was that it was causing the hole to rapidly become soft. In just a few more hours, the ground would weaken so much it would need to be completely rebuilt; a costly endeavor which could take up to a week to compete and require a bypass pump to be temporarily installed.



In an emergency situation, we are ready to pull from our back stock of prefabricated Sewer Shield Composite LLC manholes. Fortunately in this case, the manhole was among the many along the road previously inspected by our team and determined to be in dire need of repair. A completely custom composite insert had already been prefabricated and wasツready to install. I called in some of our most experienced Corrosion Control Specialists from multiple crews whom were out working shifts elsewhere. To install a composite as quickly as needed, with sewage flow coming off a high flow force main, and traffic control time running out; I knew I needed the best of the best who could be ready for any challenges that could arise. Dave Vorhese with Pima Utility got the biggest smile on his face when he saw six of our guys show up and get right to work.

We jackhammered away the remaining asphalt so we could expose the cone of the existing manhole. ProPipe was already on the site and soft dug the manhole out for us. With not much else prep work needed, we pulled the cone out with a simple backhoe and then used it to quickly insert the composite. We layered around the base with a C-120 Calcium Aluminate Concrete underlayment by Environmental Coatings LLC and installed steel plates over the top of the hole to temporarily keep cars from driving over it.

Our 24/7 emergency response team was able to use the existing bench until we could go in later and fabricate a new one. After the area around the hole had been backfilled with slurry, it was now a stable enough structure to last up to 50 years and came with a 25 year warranty. We had the sewer flowing again in just FOUR hours and the total time on site was about 4.5 hours all together. Not bad to save a major roadツfrom completely collapsing.