LIHUE — Work on a $1.1 million repair project to the Kapaia Tunnel will start in September, said David Hinazumi, vice president of the Grove Farm Company.
“The maintenance project is needed following repeated collapses to the 100-year-old, hand-dug tunnel which feeds the Kapaia Reservoir,” Hinazumi said. “Some of these collapses reduced water flow in the 10-foot-wide, 3,000-foot-long irrigation tunnel.”
The feed from the Kapaia Tunnel to the Kapaia Reservoir, also known as Tanaka Pond, fuels the Grove Farm Waiahi surface water treatment plant, which feeds drinking water to the county Department of Water’s Lihue-Kapaa water system. The surface water treatment plant supplies water to nearly 15,000 residents.
Additionally, the Kapaia Reservoir supplies irrigation water to a number of farms, ranches and other businesses in the area, as well as providing a habitat for the nene restoration project.
Hinazumi said following the collapse in April 2016, Grove Farm repaired the damage with an $84,000 debris-clearing effort. The repair was followed by a second major collapse taking place two months after those repairs.
The repair work starting in September is meant to restore stable water flow and avoid the risk of future collapses, Hinazumi said. Grove Farm will install a 36-inch-wide, high-density polyethylene pipe for the entire 3,000-foot length of the tunnel, with the project being completed by December, weather-permitting.
Hinazumi said during the construction period of September through December, helicopter tour pilots have been requested to avoid flying over the tunnel area.
The Kapaia Tunnel is only one component of a water system that stretches for miles across the landscape and includes reservoirs, dams, open and covered ditches, flumes, siphons, water-treatment facilities and other tunnels.