Leaky tanks at a Dee Why petrol station have polluted surrounding groundwater, potentially “causing harm” to human health and the environment.

The NSW Environment Protection Authority (EPA) has issued United Petroleum (UP) with a clean-up notice for its service station in The Strand.

The EPA report states petroleum hydrocarbons have been found in groundwater around the site and that the leak is thought to have come from underground storage tanks.

“Petroleum hydrocarbons have been introduced into the groundwater through soils, which has resulted in a change to the physical and chemical condition for the groundwater and have the potential to cause harm to human health and to the environment,” the report states.

The petrol station is surrounded by housing and is close to the southern end of Dee Why Beach.

Uniting Petroleum chief operating officer David Szymczak said the company was not responsible for the contamination but his company had agreed to clean it up.

“It was discovered before we owned the site,” he said. “There has been a long history of contamination here.”

Asked why the company had not taken it upon themselves to clean up the contamination earlier, he said: “Because it pre-dates us being at the site we did not see it as our responsibility. However, the EPA has decided it should be and we will clear it up.”

An EPA spokesman said it was unclear when the groundwater contamination occurred.

“The EPA was first notified of below-ground contamination in January 2017,” he said.

“A report (on the matter) was received in April 2018 and after further assessment, a Clean Up Notice was issued.

“One of the requirements of the notice is that United Petroleum investigates the extent of the contamination.”

He said from the information the EPA had there was no risk to surrounding homes and the contamination was unlikely to reach the beach.