Manhattan Beach

A fifth El Porto home has been found to contain hydrocarbon vapors, according to Manhattan Beach Assistant Fire Chief Keith Hackamack.

Hackamack said hydrocarbon levels of more than 5,000 parts per million were discovered at a home on the 4300 block of The Strand, two blocks away from where officials earlier had found underground vapor levels of 95,000 ppm. Gasoline-based hydrocarbons become potentially explosive at 14,000 ppm.

Hackamack also said that ambient levels--meaning those in the air above ground--of about 50 ppm were detected in the bedroom of the house, where the vapors had seeped in through a crack in a retaining wall.

While no conclusive link has been established, hydrocarbon vapors are believed to be seeping from the Chevron USA Inc. refinery just north of El Porto in El Segundo. Those vapors, first detected last month, have been found in a six-block stretch along The Strand. Since then, officials have reduced vapor leaks in four other Strand homes, and have blacktopped an eight-foot-wide, 200-foot-long swath of beach along the bike path where highly explosive subsurface levels were found.

Chevron is already known to have eight pools of liquid hydrocarbons under its 1,000-acre property, including a large pool that has leaked off the refinery into El Segundo’s manufacturing district.

The latest readings are part of a study Chevron is conducting to determine the extent and severity of off-site leakage of liquid and vaporous hydrocarbons.