Crews are making progress in repairing damage to Alii Drive caused by a sinkhole that opened late last year fronting Coconut Grove Marketplace.
“We are about 50% complete,” Hawaii County Department of Public Works spokeswoman Denise Laitinen said this week. “The difficult part of the project — stabilizing the sewer line, excavating behind the existing rock wall and backfilling with concrete — is about 90% complete.”
On Thursday morning, Isemoto Contracting Ltd. crews were working on the sea wall and other parts of the project as traffic made its way around the area, using a single lane.
Isemoto has been working under an emergency contract since late January, assessing and fixing damage caused by years of erosion that undermined the seawall exposed to Oneo Bay, ultimately causing a portion of the makai shoulder to sink and the wall to buckle.
Since first taking excavators to the crumbling roadway, the project has progressed with a good portion of the southbound lane being essentially rebuilt from the ground up.
The county initially anticipated the project would take about a month to complete, cautioning, however, that the timeline was fluid due to uncertainties heading into the work. After getting into the work, crews learned the original rock wall was built directly on the sand and not constructed on a solid base. In addition, the rock wall was “poorly constructed” and “not very thick.”
On Wednesday, Laitinen said Isemoto Contracting now expects to wrap up work in a month. Remaining work includes relocating a gas line and reconstructing the roadway, shoulder and pedestrian wall.
She said Isemoto’s work is constructed as the permanent repair to the wall. Thus far, $300,000 has been expended via the emergency contract.
“The new concrete gravity wall rests on the underlying bedrock and will be able to withstand future high surf events,” said Laitinen.
During the remaining work, Alii Drive fronting Coconut Grove Marketplace will continue to be restricted to one lane 24/7. A temporary signal is installed to facilitate traffic flow during the work.
In addition, the makai shoulder of the road, which has been closed to pedestrians since the sinkhole appeared Dec. 24 will remain closed until work is complete.
Erosion of the seawall fronting Coconut Grove Marketplace is an issue that has cropped up in the same spot for years, including in 2015 and spring 2019, and is the result of years of ocean crashing against the wall and circling in the area.
County officials have been aware of the undermining of the seawall at Oneo Bay for over a decade. The project has been on the books since at least 2001, with the capital improvement budget showing federal and county funds allocated for the project over the years. It was also part of a 2009 draft environmental assessment for improvements to Alii Drive between Hualalai and Walua roads.