A portion of the recreational bicycle and pedestrian path in Kapa‘a could be damaged if an erosion-weakened seawall fronting the Pono Kai condominiums is not repaired, a Honolulu engineering and planning consulting firm told the Kaua‘i County Council. And the
A portion of the recreational bicycle and pedestrian path in Kapa‘a could be damaged if an erosion-weakened seawall fronting the Pono Kai condominiums is not repaired, a Honolulu engineering and planning consulting firm told the Kaua‘i County Council.
And the placement of new sand — taken from periodic dredging of the nearby Waiakea Canal in Kapa‘a — would help soften the blow of waves that pound the wall, thereby extending the structure’s life, Dr. Warren Bucher of Oceanit said Wednesday at a council committee meeting at the historic County Building.
“The beach has been moving offshore or along the shore, and as the beach level goes down,” Bucher said. “It exposes more of the wall.”
If the repair work is not done, the entire 600-foot-long wall, which now has sinkholes behind it, could collapse, said Dr. Dayan Vithanage, a colleague at Oceanit.
The consultants gave a rough estimate of $1.4 million for the work, but Kaua‘i County Councilman Kaipo Asing wondered whether the expenditure was necessary because sand moves in and out of beaches each year.
“Is (the need for the work) real?” Asing said. “I don’t know, and I question that.”
Bucher said historical photos will confirm his assessment, but hinted strongly an unrepaired seawall could be further degraded by continual erosion, creating a larger financial burden for the county later.
The councilmembers took no action on the recommendations by the consultants.
At a cost of $6,500, the county hired Oceanit to produce the report and recommendations.
Through an emergency process for repair work, Bucher said Oceanit will submit to the county a proposal for ways to fix the wall. The repair work will be done by other entities.
As a safety precaution, the county has closed off either all or most of the seawall.
Bucher said the seawall was built through an emergency process after damage to the island by Hurricane ‘Iniki in 1992.
Oceanit engineers visited the area on July 31, and confirmed county findings of damage to the wall.
“The wall has a concrete cap, which is cracking in places, and it indicates the wall is moving due to erosion,” Bucher said.
The problem might have been alleviated had a filter been placed behind wall when it was built, he said.
Without the filter, sand has been removed from the seawall by constant wave action that has pounded the structure since it was built, Bucher said.
“The loss of fill material through the wall also threatens the stability of the wall,” the consultants said in their report.
The erosion has occurred because two jetties by the Waiakea Canal have prevented waves from bringing a sufficient amount of sand northward to the beach near the seawall.
County officials might consider repairing the seawall rather than replacing it, due to cheaper cost with the first option, Bucher said.
Work would involve digging down behind the wall to its foundation, and shoring up loose rocks with steel sheets, a method that would help the wall stand upright, he said.
Beach replenishment is not mandatory, but would protect the wall, Bucher added.
Vithanage said sand can be taken from the next dredging of the Waiakea Canal and recommended not removing the jetties or groins to ensure safe passage of boaters into the canal.
Bucher estimated the design and planning for the repair project at $120,000, the repair of the wall at $500,000 and the replenishment of the sand at $800,000, totaling about $1.4 million.
He said the rough estimates could go up or down depending on the contractor used and cost of materials.
Councilwoman JoAnn Yukimura said the county could defray costs by securing state help in its next capital improvement budget package to the Legislature for fiscal year 2008-2009.
With seasonal changes in the sizes of beaches, Asing, a lifelong fisherman and Hawaiian waterman, wondered whether such expenditures are necessary.
“Throughout my life I am very familiar with the Na Pali Coast and Ha‘ena and see beaches disappear, and during the summer months, like 50 or 100 feet of beach that was non-existent months ago (comes back),” Asing said.
Bucher agreed with that assessment and noted historical photos will verify such trends.
But the Pono Kai Beach area is different because of the sand-robbing characteristics of the two jetties at the Waikaea Canal, the consultants said.
County Engineer Donald Fujimoto and Bernard Carvalho, who heads the new county Parks and Recreation Department, will be working with Oceanit on recommendations for the repair work and associated costs.
