By Chris Richard and Lisa Pickoff-White

During the last 25 years, California water regulators have identified 43,000 fuel leaks. Now, all but 6,000 have been cleaned up. This interactive map shows 1,547 fuel leak sites that are still designated as "open and eligible for closure." These are the ones that are most imminently subject to a relatively new "low-threat" policy.

The map omits cleanup and monitoring locations already officially closed as of Feb. 1, 2014. There generally is little change in the course of a month.

Enter your address below to see how many of these sites are close to you.

[ad fullwidth]

Some fuel sites are easier to clean than others. Officials at the Water Resources Control Board decided in 2012 to stop paying for cleanup and monitoring at other sites that pose no immediate threat to the drinking water supplies or the environment. That policy is known as the Low-Threat Underground Storage Tank Closure Policy.

But at some sites, the policy allows petroleum contamination to remain in the ground at much higher levels than what had previously been allowed. According to state officials, those cases can safely be resolved by biodegradation, in which naturally occurring microbes in the soil consume petroleum and petroleum by-products.

[contextly_sidebar id="0c852be6e79820270fa4c7f4991415a8"]

Some scientists, as well as local and state regulators -- including engineers and geologists currently or recently employed by the semiautonomous regional water quality control boards -- question the Low-Threat strategy on several grounds.

They warn that the policy allows contamination to remain in the ground at levels many times higher than those previously allowed by the state water code and the board’s own long-established policy.

Officials at other water districts are concerned by the Water Resources Control Board's assertion that contaminants left in the ground are now part of the environmental status quo.

Industry groups -- the Western States Petroleum Association and the California Independent Oil Marketers Association -- support this policy.

How to find out more about a specific site

Every icon contains a link to state records on that site. Some of the most important information is in the "correspondence tab."

In that correspondence, look for a request for closure like this one, which presents the remediation company's arguments for closing the site. These will seek to satisfy the conditions laid down in a Water Resources Control Board checklist. Responses may include a draft closure order, as well as challenges to the request, such as this one from the Orange County Water District.

To double-check your neighborhood, you may want to visit Geotracker, where the database is revised daily.

Common technical terms and definitions

Aquifer:
A subterranean layer of rock, sediment or soil containing water. Aquifers contain pores that, when connected, allow water to flow through them. Wells draw upon aquifers.

Bioremediation or biodegradation:
The breakdown of contaminants by natural, often biological, processes.

Cone of depression:
The area around a pump in which groundwater is drawn toward the pump. Think of the funnel shape that water takes as on the way down the drain. Typically, the stronger the drawing power of a pump, the bigger its cone of depression.

Dissolved phase:
Contamination that has dissolved into the groundwater.

Free product:
Petrochemical contamination that is identifiable as a discrete substance instead of being mixed with water or soil, seen as an identifiable layer or sheen.

Gradient:
The subterranean flow of groundwater. This doesn’t necessarily conform to the slope of the surface, and is changeable. For instance, the rate at which nearby pumps draw water from the ground can change the gradient.

Groundwater:
Water moving through the soil or rock under the ground.

Hydrocarbons:
Fuels and oils that are identified by their main constituent, hydrogen and carbon

In situ:
On the spot, in other words, in the original position. For instance, if the soil is treated without being dug up and hauled away, that’s called in-situ remediation.

LNAPL:
This stands for “Light Non-Aqueous Phase Liquid,” in other words a liquid that is less dense than water and that, instead of mixing with the water, floats on top. This term might be used to describe gasoline, diesel and other petroleum products.

Monitoring well:
Wells, often distributed along a plume’s periphery, that allow collection of contamination samples

PAH:
This stands for “Polycyclic Aromatic Hydrocarbons,” a class of contaminants that share a structure of linked benzene rings. They can be found as contaminants in hydrocarbon compounds, and are of concern because they are believed to be carcinogens, mutagens and teratogens.

Plume:
A defined area of soil or water that is contaminant, with the contaminant originating in an identified source.

PPB:
Parts Per Billion. If 1 gram of a substance has a contaminant level of 1 ppb, that means it contains a billionth of a gram of the contaminant.

PPM:
Parts Per Million. If 1 gram of a substance has a contaminant level of 1 ppm, that means it contains a millionth of a gram of the contaminant.

Sparging:
Injecting air into the soil or groundwater to strip away contaminants and increase oxygen concentrations

leaking fuel tanksleaking fuel tanks

Map of Fuel Leak Sites in California: How Close Are They to You?