WORK on the Lomaloma trans-insular road between Savusavu and Labasa may not be completed by May 18.
China Railway First Group Limited revealed the slip project is valued at $5,399,871.
Company spokesman Donald Singh said the project cost $5.4million.
Mr Singh said the total linear length of the project was 309metres for both the slip and road repair.
He said so far, they had completed works accounting to 49 per cent of the total amount of the contract.
"Backfill work has been drastically affected due to the rainy season and excessive rainfall between January and March this year.
"This has affected the projected completion time for the project.
"Currently, we have begun backfill work and we are progressing at a rather slow rate in order to ensure full compliance with engineering requirements."
He added some constraints included the size of backfill material, which was being sorted out by further stone crushing to achieve the 65millimetres required by engineers.
"The project has been affected by high precipitation. Although the rainy season has concluded, even slight rain in this area stops filling works."