API Publication 341:1998 pdf download

API Publication 341:1998 pdf download.A Survey of Diked-Area Liner Use at Aboveground Storage Tank Facilities.
These findings are confirmed by the New York State Department of Environmental Conservation (NYSDEC). In a 1993 memorandum addressing inspection certification of secondary containment systems, NYSDEC noted the difficulty in ensuring performance and verifying the integrity of diked-area liners. The document states that “all secondary containment systems are exposed to numerous physical and environmental conditions which can render a system faulty. Spray-on liners are subject to puncturing. Clay liners are prone to desiccation and cracking in dry environments. Frost or vehicular traffic may cause damage to the liner material.”
The memorandum also notes that “problems of design such as short-life materials or construction and compatibility with petroleum have caused a number of secondary containment system failures.” The NYSDEC memorandum goes on to discuss the problems and engineering approaches associated with the inspection and evaluation of various liner systems.
API’s data indicated that it is difficult to test the containment system after liner installation. Visual inspections are not reasonable for liners that are covered with soil or stone. Maintaining diked-area liners is complicated by the fact that there are no methods for assuring integrity.
Effectiveness in Containing Releases
Survey respondents indicated that few releases had occurred at their facilities that would be addressed by diked-area liners. Twenty-nine facilities or 91 percent of all responding facilities indicated there had been no release since the liner had been installed. Twenty- seven facilities or 84 percent of responding facilities reported that the liner system had been in use for five years or more, and of this subset, 93 percent reported that there had been no release into the diked area during that time period.
Because there were few releases, the data do not directly demonstrate the effectiveness or ineffectiveness of liner systems in containing releases. Only three facilities experienced a release after the liner was installed. Two of these facilities reported that the liner system contained the release; one indicated that the liner did not contain the release. In the latter case, the liner system failure was attributed to improper installation.
Effect on Facility Operations
Twenty-eight or 88 percent of responding facilities indicated that the liner system had adversely affected facility operation. The three major areas of concern were:
• Limited access to the tank farm (because of potential damage to the liner from vehicular traffic). Over the lifetime of a tank, access is needed for operating, inspecting and maintaining the tank. Constant care must be taken not to damage the liner during routine operations and maintenance.