Heritage has completed 20% of the overall clean-up operations of an oil spill at Massahood, Fyzabad.
Heritage Petroleum Company Limited says this includes the removal of heavy deposits and impacted soil.
In statement on Tuesday, the company indicated it had been unable to carry out routine checks and maintenance of the 16-inch Trunk Oil Pipeline because of an illegal structure built on the active pipe line.
It added the next stage of clean up, which has already commenced, involves sanitising and power washing the affected area as well as the removal of heavy deposits and impacted soil.
Heritage indicated emergency medical technicians are stationed in the area on a 24 hour basis and the company continues to monitor the air quality in the area.
Regulators from the Environmental Management Authority (EMA) and the Ministry of Energy and Energy Industries visited the site on Monday to observe the response in progress.