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Wednesday, June 02, 2004 11:40 AM Art Gomez 510-494-1596 p.16 TRUCHEKI Monitoring System Double-Wall all ttn at its Hest Xerxes DWT-II double-wall tanks with the TRUCHEK'"system option are factory-filled with a monitoring fluid in the Diagram A interstice between the two tank walls.The monitoring fluid also partially fills a reservoir affixed to the top of the tank.This creates a hydrostatic pressure that enables owners/users to monitor both the primary-tank and the secondary-tank walls. Reservoir The TRUCHEK"system provides a simple and precise Level Down method to perform a tank-tightness test. It was developed in conjunction with Robert Plunkett, Sc.D., consulting engineer (professor emeritus), University of Minnesota.TRUCHEK"has received third-party verification from Underwriters Laboratories. TRUCHECK"testing meets the EPA criteria for tank-tightness testing,which states that a test must be able to detect a leak rate of 0.1 gallon per hour from any portion of the tank that routinely contains product.The test has a 95% probability of detection (PD) and a 5%probability of false alarm (PFA). In other words, out of 100 chances, the test detects leaks 95% of the time. The test must also account for the effects of thermal expansion or contraction of the product, vapor pockets,tank deformation, evaporation, condensation and the location of Diagram B the water table. TRUCHECK'1'is capable of detecting a loss rate as small as the NFPA 329 criteria of 0.05 gallons per hour. Reservoir In addition, on extended tests, TRUCHEK^"testing offers 99% Level Down PD and I% PFA. The TRUCHEK° Test Offers Significant Benefits to the Owner/Operator: 1.A wide range of tank sizes can be tested, including Xerxes DWT-II tanks up to 30,000 gallons. 2. Product can be dispensed during the 9S%-5%test. 3. No waiting time is required to start the test as long as a fill of new product does not vary more than 20°F from the existing product temperature. How Continuous Monitoring Works Diagram C If both the inner and outer walls are tight, the reservoir level will be stable. "'•-'��' " '��' �•^•--• �•--- -Reservoir-d- If there is a leak in the inner wall Level Up L-Water Level (Diagram A), the brine level in their ,,.-.�. �-.�-_- .. -•.�,,,, , .-� .,•„��— :::-_ •• ... �••�.Above Tank reservoir will go down.The brine �. ..�- -.w level will also go down if there is �•---� J �~'Leak in a leak in the outer wall (Diagram B). :�.`.- r Outer Wall With a high water table and"wet-hole” conditions (Diagram C), a leak in the "�••� .� outer wall will cause the brine leveler = ,� to go up if the height of the r water table above the leak is �,,•. ,� 30% greater than the brine level above the leak. �^ See Xerxes TRUCHEK°" brochure for more details. ••�,_..-�,...- .,,.-,��...,,•;;..�,,a,.