The Commercial Real Estate Informational Portal

Welcome to

Welcome to the Commercial Real Estate Expert Blog! A host of industry leading real estate professionals, lawyers, and consultants providing the latest in real estate relevant news and advice.

CA Water Board’s Low-Threat UST Closure Policy

In California where environmental regulations are famously conservative, a policy went into effect last fall making it a little easier to close certain low-risk sites contaminated by leaking petroleum underground storage tanks.  Owners or responsible parties of these leaking UST sites should be aware of this program to see whether their site qualifies.

Overview of the Low-Threat Underground Storage Tank Case Closure Policy

The California  State Water Resources Control Board, also known as simply the State Water Board, adopted a policy on May 1, 2012 regarding the closure of sites with leaking petroleum underground storage tanks (UST). The new policy established consistent statewide criteria  for case closure of a subset of low-threat petroleum UST sites. To qualify as such, a site must be  without unique characteristics or site specific conditions that increase risk to human health, safety or the environment, and that meet general and media-specific criteria.

The Low-Threat Underground Storage Tank Case Closure Policy appears to be an effort to balance the protection of human and environmental health with the realities of limited technical and economic resources. The policy cites experience and literature to establish that standard remedial technologies and efforts can remove substantial quantities of petroleum contaminants. The policy also states that extra effort to remove residual petroleum contaminants can be difficult and costly as well unnecessary considering  natural attenuation slows and limits the migration of dissolved petroleum plumes in groundwater and the environment.

Criteria for Low-Threat Leaking Underground Storage Tank Sites

General criteria that must be satisfied by all candidate sites are listed as follows:

a. The unauthorized release is located within the service area of a public water system;

b. The unauthorized release consists only of petroleum;

c. The unauthorized (“primary”) release from the UST system has been stopped;

d. Free product has been removed to the maximum extent practicable;

e. A conceptual site model that assesses the nature, extent, and mobility of the release has been developed;

f. Secondary source has been removed to the extent practicable;

g. Soil or groundwater has been tested for methyl tert-butyl ether (MTBE) and results reported in accordance with Health and Safety Code section 25296.15; and

h. Nuisance as defined by Water Code section 13050 does not exist at the site.


For more information, visit the State Water Board’s website at or contact Partner‘s Site Mitigation group at 800-419-4923.