Client:
City of Baltimore
Type of Project:
1000 Gallon UST Tank Test
Location:
Department of Transportation, Edmonson Ave., Baltimore, Maryland
Services:
Test 1000 Gallon UST for Recertification
A temperature probe and test column
are put into the tank.
A2Z was under contract with the City of Baltimore to test 216 of their Underground Storage Tanks (UST) for recertification to make certain the tank met industry standards for Maryland Department of the Environment. A2Z‟s tank tester arrived at the site and advised the director he was ready to start testing the waste oil tanks for leaks.
The level of waste oil in the tank was checked, The tank was full. They had prepared properly for A2Z to perform the test. The equipment used today is Tel-A-Leak, which consists of a temperature probe and a test column. A deflection was needed on the ends of the tank.
To do this, the tank tester must raise the pressure in the tank. This was accomplished by using the following for-mu la. The tank tester took the diameter of the tank, (48 inches), added the length of the fill tube, (36 inches) and multiplied it by the PSI of the product in the tank. Waste oil is .031 for our pur-pose D+LxP=PSI or (48+36) x .031 = 2.604 PSI. A2Z installed the test column directly into a manifold system and raised the column an additional 47 inches to create a positive 4 PSI. This is a requirement per industry code. The testing process actually began when the first test column was filled with additional diesel fuel, and allowed an additional 15 minutes to see if the UST would begin to build pressure on it‟s own. The key to the 15 minute time frame is that the manifold valve will have product coming out of a "double A" valve. Once this occurs, we know that the system is building pressure on it‟s own. However this doesn't mean the UST would pass the precision test..
The tank should be filled to the maximum
for a Tel-A-Leak precision test.
The next step in the testing process was to take liquid readings from the test column and temperature readings from the temperature probe in the UST for one hour. This resulted in a system failure. The system was losing 3 lines per minute, which constitutes a leak rate of .612; the threshold number for failure for this tank is .05 or 189 ml. The tank had to be excavated to expose the tank and its parts. After testing the tank only, it was determined that there was a leak in the remote fill pipe and the vent pipe.
A2Z installed a new remote fill pipe and vent pipe, backfilled the area and installed a new concrete pad, and then retested the system. The new test showed that the tank was now within industry code. A recertification was granted