Safely Closing Underground Tank: D.H. GRIFFIN's Contribution at High Point University

High Point University, an expanding university located in North Carolina’s Piedmont Triad, requested D. H. Griffin’s Environmental Division to provide for the closure of an underground storage tank (UST) in preparation for building demolition and redevelopment.

The size of the UST and the quantity of remaining product was unknown, however the tank was believed to contain #2 Fuel Oil used to supply a large furnace system. Upon a site inspection the tank fill port was located in a parking lot approximately 100ft from the boiler room. After removing the fill cap, the product level was visible and nearly full. A calibrated gauge stick was inserted into the tank indicating the tank diameter was 8ft. and contained 80 inches of liquids that appeared to be #2 Oil. We then applied water detection paste on the gauge stick and reinserted into the tank, the paste only indicated 4 inches of water in the tank bottom.

Using calibrated tanks charts and based on an 8ft diameter tank, we were able to estimate the UST contained anywhere between 4,500 to 10,500 gallons of good quality #2 oil for resale. Our vacuum truck was utilized to pump 6,900 gallons of product from the tank, which was delivered to a local logging company for use in off-road equipment.

Following the removal of the useable product an excavator was utilized to expose a portion of the tank top. We used our combustible gas meter to test the interior atmosphere of the tank for flammable vapors, the meter indicated no flammable vapors were present. Upon completion of a Hot Work Permit a sawzall was used to saw cut a clean out manway into the top of the tank. Utilizing confined space entry procedures and our personnel retrieval system enter was performed inside the tank to remove residual sludge, followed by pressure washing the tank interior to remove hydrocarbons. A measurement was taken from inside the tank which indicated the UST to be 24ft in length, this would be an 8,000 gallon tank.

After obtaining a tank removal permit from the local fire department the excavator was used to remove the surrounding soil from the tank. The proper lifting chain was attached to the tank lifting lugs, lifted and loaded onto a D. H. Griffin trailer for delivery to our scrap yard.

Following the tank removal we assisted a licensed geologist to conduct soil sampling for the NCDEQ closure report. Upon clearance from the geologist we imported clean backfill and placed into the excavation.

This project was completed safely in 2 days with added value gained from the resale of the remaining fuel oil.