A wretched smell that engulfed the area surrounding the Oceanside Treatment Plant is expected to clear out by the end of today.

The smell was caused by dirty sand that was dumped outdoors in piles after clogging up the sewage treatment plant, which is located next to the zoo, according to San Francisco Public Utilities Commission spokesman Tyrone Jue.

The sand was whipped off Ocean Beach onto surrounding rooftops and streets, where it ran into gutters and drains before ending up inside the treatment plant.

“We had a blast of sand which overwhelmed the treatment plant,” Jue said. “We had to pull out that sand.”

Late Monday, water treatment officials shoveled sand away from filtration screens inside the treatment plant and dumped it in two piles outside, according to Jue.

A waste hauler collected the sand on Tuesday morning and it will be dumped in landfill, according to Jue. Chemicals were applied to the area where the stinking sand was piled and the odor is expected to dissipate by this afternoon, he said.

The problem occurs once or twice a year and is expected to be addressed in the future through the multibillion-dollar Sewer System Improvement Program, according to Jue.