By Jan TenBruggencate
Advertiser Columnist

A state law requires that government road paving projects in Hawai'i use recycled glass when possible, but only Maui County uses most of its recycled glass in road construction.

State Department of Transportation spokesman Scott Ishikawa said he could not get a firm figure on the amount of glass being used in O'ahu roads. The problem is that the department combines recycled materials in its statistics, so both recycled glass and recycled asphalt pavement are included in its figures for "glassphalt," and most of it is old pavement.

"The mix of glassphalt in road construction material ... came out to about 20 to 25 percent," he said.

In 2000, 125,332 tons of material were used in O'ahu highway projects. Of that amount, 20,850 tons consisted of recycled materials. Last year, 21,884 tons of material were used, and 3,636 was a combination of recycled glass and recycled pavement, according to figures provided by Ishikawa.

Figures from the state recycling office suggest that only about a sixth of the glassphalt comes from glass. They show that 696 tons of recycled glass were used in O'ahu road construction in 2003.

That represents less than 10 percent of the 7,756 tons of glass collected on O'ahu during 2003. An additional 2,657 tons were used as fill on construction projects. The majority, 4,403 tons, was shipped to the Mainland to be converted back into glass products.

On Maui — the state champion in using recycled glass in road construction — some 95 percent of the glass collected by Aloha Glass Recycling ends up in roads. In 2003, 1,185 tons of glass, out of a total of 1,208 tons collected, was used in paving material. The remainder was used as sandblasting grit and for water filtration.

The Big Island used virtually all of its 1,585 tons of recycled glass as landscaping material. And on Kaua'i, most of the 643 tons collected was used for fill in pipe trenches, under houses and behind retaining walls. Some was also used for roads and sandblasting, but distinct categories of use were not broken down.

Statewide, glass recycling by the counties has been fairly stable, between 11,000 and 14,000 tons the past six years.

Recyclers say their biggest problem is an uneven flow of glass into recycling projects. Tom Reed of Maui's Aloha Glass Recycling said he sometimes must store hundreds of tons of glass before it is used.

If you have an issue, question or concern about the Hawaiian environment, drop a note to Jan TenBruggencate, The Advertiser's Kaua'i Bureau chief and its science and environment writer. Reach him at jant@honoluluadvertiser.com or (808) 245-3074.