Residents hear rockfall plan
By James Gonser
Advertiser Urban Honolulu Writer
Nine months after a 350-pound boulder rolled down a hillside and came to rest in a resident's back yard in Kalawahine Valley, a plan to secure the area from more falling rocks has been completed.
The plan presented to Kalawahine Streamside residents last week includes building a fence in one area and securing rocks in another, at a cost of $800,000 to $1 million.
With officials saying there's no immediate danger, the work has no start date. But residents still worry that a loose boulder could fall down the hillside at any time, causing injury or damage.
"The meeting was to give the beneficiaries and the lessees the security that we are going to step forward and get this taken care of, regardless of how we are going to pay for it and what it is going to cost," said Micah Kane, chairman of the Hawaiian Homes Commission. "We are going to recommend to them the safest remedy for the situation."
Kalawahine Streamside is a $26 million Hawaiian Homes project behind Roosevelt High School developed in April 2001. The neighborhood consists of 54 multilevel duplex units and 33 three-story, single-family homes built by Kamehameha Investment Corp., a for-profit subsidiary of the Kamehameha Schools trust.
Denise Ka'a'a, president of the Kalawahine Streamside Association, said residents are happy to hear about plans to make their neighborhoods safe, and eager to see work started.
"We've heard the recommendations, but we just have to see if the developer is actually going to do it or not," Ka'a'a said. "They said the right things that we wanted to hear, but until it is actually implemented, we have our reservations."
The proposed work would make Kalawahine Streamside the latest area to undergo work to minimize danger from falling rocks. Several rockfalls have heightened concerns about safety and liability since August, when a 5-ton boulder crashed through a Nu'uanu home and killed a woman as she slept.
Some developers and land owners have responded with new rockfall mitigation measures.
In Waimanalo, the state is erecting mesh above Makapu'u Beach to stop rocks from falling on Kalaniana'ole Highway.
In Hawai'i Kai, a catchment area is being widened, problem boulders will be broken up or anchored in place, and mesh will be installed over the area at the Lalea development, where a boulder fell and smashed parked cars in November.
The work is being undertaken by Kamehameha Schools, owner of the area above the Lalea property, and developer Castle & Cooke Hawai'i.
The city and developer have taken special measures to assure safety at the Le'olani development in Kamilonui Valley, including a soil study to determine the effects of construction on the stability of the slopes below Mariner's Ridge, a reduction in the number of homes that will be built and a requirement that potential home buyers be notified of the risk of rockslides.
At Kalawahine, several rocks have fallen into residents' yards, but none has caused serious damage.
Kane said Geolabs Inc. conducted a rockfall evaluation study in the subdivision, including a manual identification of rocks and a topography assessment, but he declined to release a copy of the report.
"The study indicated there is no immediate pressing danger, which allows us to take a more prudent approach toward mediating this situation," Kane said. "Because there is no immediate concern, we can address some specific concerns on specific rocks that will take care of it."
The plan is to build an "impact fence" behind one section of homes that would catch any falling rocks and absorb the impact.
"It has proven to be very effective," Kane said. "It would give us about a 97 percent safety factor. There is a 3 percent factor that you can never anticipate."
Another section does not need a fence, he said, but any rocks deemed potential problems will be removed or secured.
The work could be completed in about eight months if the association agrees to the plan and it is approved by the Hawaiian Homes Commission, Kane said.
"We are going to make sure it is taken care of," Kane said. "We are in discussion with (developer Kamehameha Investment Corp.) on how we are going to mitigate this. But regardless of who is going to pay, it is going to get done."
Ka'a'a said there are boulders perched precariously on the slopes above other homes.
Recently, a resident was in his back yard when a rock less than 12 inches in diameter narrowly missed him and hit his home.
"We don't care how big or small it is," Ka'a'a said. "If it is the size of a baseball, if it has some momentum, it can do some damage. We are trying to be patient, but we don't have time on our side. We get a lot of rain up there. Every time it rains, there is a risk of dirt coming down and loosening boulders up there."
Reach James Gonser at jgonser@honoluluadvertiser.com or 535-2431.
