Keene State College Underground Tank Replacement

The Keene State project was conducted over the summer of 2014. This project included every service that CommTank provides including underground tank removal, soil and water remediation, sheet piling, fractation tank rental, fuel tank rental, underground storage tank (UST) and Perma-Pipe installation, Veeder-Root Automatic Tank Gauge upgrade, hydrostatic spill bucket and tank testing.

Keene State College required these services because the existing underground tank had failed cathodic protection testing and there was heavy corrosion in the fuel supply piping. The existing UST was the second tank to be installed in this location. The previous UST had leaked 60-years prior and had never been remediated. It was an open case with the NH Department of Environmental Services (DES) and they were the acting oversight for the site remediation.

The first phase of the project required the installation of a 3000-gallon temporary aboveground storage tank to supply #2 fuel to the boilers on site. CommTank then cleaned the two existing 20,000-gallon underground oil tanks and transferred the hazardous waste in to drums. The previous generation of tanks had leaked #6 fuel oil so approximately 58 tons of contaminated soil had to be removed from the tank grave. One hundred and sixty thousand gallons of water was pumped from the excavation because of the high water table surrounding the tanks. The unusually heavy rain storms in July and flash flooding of the Ashuelot River contributed to the water accumulation. CommTank acquired permits from the state and permission from the city to filter/treat the water and discharge clean water to the town sewer system. During the wettest weather, the excavation would fill with 35,000-gallons of water over a weekend and need to be emptied before work could resume the following week.

The two new 20,000-gallon Highland HotShot underground storage tanks were tested and then installed. CommTank provided ballast for them and strapped the tanks in place. The backfill for the tanks was created by screening the native soil using a rotary screening machine. Once the backfill surrounded the tanks, CommTank crews started placing the parts on the USTs. The new tanks were connected to the boilers using two 100 foot runs of Perma-Pipe. Perma-Pipe is an insulated double-walled piping system that allows the transfer of liquids and gases at near constant temperatures. Up to 150A of low voltage heat trace current is run along the side of each pipe which provides 140 degree Fahrenheit operating temperature. The Perma-Pipe used in this project included a leak detection and heat trace system. Before the pipe could be installed the existing pipe and tunnels were demolished and new trenches were dug. Once the Perma-Pipe was welded, we rebuilt the concrete tunnels and backfilled the area with sand.

New technology was used on this project that hadn’t been installed at previous UST installations. Double-wall spill buckets with liquid sensors, sumps with sensors at the termination of the Perma-Pipe and redundant liquid level probes inside the tank were installed. The existing Veeder-Root TLS350 automatic tank gauging system was upgraded to monitor these probes and sensors. A new 12” thick pad was installed over of the new Highland HotShot USTs and 36” steel manways were set over each tank sump so that piping can be accessed for servicing. The staff at Keene State College was pleased with work done by CommTank on this project and have asked to be a reference for future projects.