UST Program - Local Guidance (LG) 141

To: Local Agencies

This letter is to inform the regulatory community that the temporary exemption for hydraulic lift tanks (HLTs) will become permanent on January 1, 1996. Governor Wilson signed SB 1191 on October 5, 1995 (Chapter 639 of 1995). One of the provisions of that bill was the change in Section 25281(x)(1)(D) which eliminated the date upon which the exemption was to expire. The previous language stated that an underground storage tank does not include:

Until January 1, 1996, a tank holding hydraulic fluid for a closed loop mechanical system that uses compressed air or hydraulic fluid to operate lifts, elevators, and other similar devices.

The State of California's decision to permanently exempt HLTs from regulation under the UST law was based in part on the SWRCB's recommendation contained in the Report on Hydraulic Lift Tanks, dated February 1995. This report concluded that leaks from HLTs do not pose a significant risk to water quality in California. Of the estimated 73,000 HLTs in the state, 78 leaks to the environment were reported to regulatory agencies. Only five of the 27 leaks that reached ground water required cleanup to avoid an adverse impact on drinking water or other current uses of ground water.

With regard to toxicity, a literature search revealed no reported human toxicity associated with the ingestion of petroleum or vegetable based hydraulic oils. Regarding environmental fate, the report concluded the following:

• The base oils are relatively insoluble in water.
  
  
• The base oils are less dense than water, so any release to ground water will tend to float on top of the aquifer.
  
  
• The base oils have low volatility, tend to adhere to soil particles, and are relatively immobile in a subsurface environment. Leak plumes would be expected to be small and to not travel far from the point of release.
  
  
• The base oils are low in aromatic compounds, such as benzene, which poses a hazard in drinking water.
  
  
• The base oils will biodegrade, at least partially, after they have been released into the environment.
  
  
• The primary route of exposure after a release will be possible human ingestion via degraded drinking water.
  
  
• The human toxicity (measured in terms of ingestion associated with these oils) is apparently very low or nonexistent.
  
  
• It is unlikely that other species of organisms will be adversely affected by HLT releases under the conditions described above.
  
  

Sincerely,

[Original signed by:]

James George Giannopoulos
Underground Storage Tank Program Manager