Hawaii construction workers have been slowed down by dense high-temperature rock while reconstructing a Big Island highway inundated by lava in the 2018 Kilauea volcanic eruption, a report said.

The Hawaii County Department of Public Works is seeking more time from the Federal Highway Administration to facilitate proper construction, the Hawaii Tribune-Herald reported Wednesday.

“Work crews have encountered very dense lava rock in this area, which is slowing the pace of work,” department official Denise Laitinen said. “Once the rough grading is complete on the lower portion, the fine grading can be spread before the road is paved.”

The rock is dense, making it difficult to drill, and also hot and needing time to cool before it can be handled.

Construction crews are working with cooling lava rock on Highway 132 above 700 degrees Fahrenheit (371 degrees Celsius) in some areas “where the concern is for temperatures that exceed recommended levels for the installation of asphalt-treated base,” Laitinen said.

The department is also asking for permission to open the road in two phases as construction will be completed in the upper section first before the lower section, officials said.

When the highway is complete, it will grant access to some residents’ land-locked homes and farms about 24 miles (39 kilometers) southeast of Hilo, officials said.

“Crews are working hard to meet the Oct. 5 deadline in order to qualify for 100% federal reimbursement of the project,” Laitinen said.