Where does it go? A Closer Look at Oahu’s Waste Stream (Grey Bins)

Nov 17, 2011 by Rachel Harvey | Story Popularity: 12

When you throw something away, do you ever wonder where is away?

It is important to understand the character and outcomes of Hawaii’s municipal waste stream. For all our islands, especially populated Oahu, waste management is a critical civic issue.

Kanu Hawaii Waste Team members recently took a tour of the Opala facilities.

According to Waste Management, Inc., on Oahu roughly 1.6 million tons of waste are generated each year (That’s over 60% of the state’s total waste output!). HPOWER, which is the City and County's waste-to-energy facility, processes 600,000 tons of waste. Another 200,000 tons are deposited into a private construction and demolition landfill. This leaves roughly 400,000 tons of waste a year that is brought to the City's Waimanalo Gulch Landfill, including 100,000 tons of ash per year generated by HPOWER incineration. Approximately 500,000 tons of reusable waste - including green waste, tires and concrete, are recycled through a variety of programs.

For those of you on Oahu, trash that goes into grey curbside bins or dumpsters (meaning trash not separated for reuse, recycling, or composting) makes its way to H-POWER, or the Honolulu Program of Waste Energy Recovery, owned by the City and County of Honolulu and managed by Covanta Energy. The main mission of HPOWER is to reduce the waste mass that goes to the landfill, transforming it into ash, and generating electricity in the process.

Waste trucks are weighed as they come into the station and collected materials are dumped in a main warehouse floor. One day of collection easily fills the tipping room. Here bulldozers sort out bulky waste that will no t fit through the shredders such as mattresses. In the shredding process, metals, such as steel, aluminum, and foil, are extracted using magnets and sent for recycling.

Waste is then combusted in furnaces at temperatures approaching 2,000 degrees Fahrenheit and reduced to an ash residue that is only 10% of its original volume.  HPOWER runs two current combustion furnaces 24-hours a day, processing about 2,000 tons of garbage. A third structure is under construction and will come online next summer, adding 30 more jobs and the ability to process 900 more tons per day. The new facility will likely be able to shred more bulky waste. Each year HPOWER burns about 600,000 tons of trash. This is a 60% reduction of Oahu’s solid waste. From this process 100,00 0 tons of ash are sent to the landfill.

The generated heat uses a steam turbine to create electricity. Currently, HPOWER generates 7% of Oahu’s electricity – 45 megawatts or enough to power 40,000 homes. The addition of a third burner will create 30 more megawatts.

HPOWER has a number of measures in place to prevent pollution and is approved by the EPA. Highly efficient combustion controls potential organic pollutants as well as carbon monoxide during burning. Ash is treated with a lime and water slurry mixture to control the boiler outlet gases. The lime slurry mixture neutralizes acid gases, such as sulfur dioxide and hydrogen chloride, and cools the outlet gases as well. Emissions data is constantly monitored and regular reports are sent to the Hawaii Department of Health.

The Landfill
Waste overflow as well as bulky items, such as mattresses and construction waste are sent to the Waimanalo Gulch Landfill. The landfill takes in 400,000 tons of waste per year including 100,000 tons of ash. The resultant ash from HPOWER is sealed in a separate lined area.

The Waimanalo Gulch Landfill, overlooks the scenic Ko’olina Marina. Nestled in a natural gulch, the landfill is built into this low spot in the landscape on 200 acres. The landfill opened in 1989 and estimates 20 more years of capacity. The Waimanalo Gulch Landfill is owned by the COCH and operated under a contract with Waste Management of Hawaii.

The landfill is maintained in a “honeycomb” method. Only a small portion of the landfill is uncovered each day as a two-foot layer of rubbish is crushed and placed by bulldozers. The rest of the landfill area and each new rubbish level is covered by a layer of topsoil. This reduces the potential for odor, materials reaching wildlife, or storm run-off.

Three layers of plastic and fabric liners protect against seepage. At the bottom of the landfill pockets, or a “sump,” are maintained to collect and reroute contaminated rainwater run-off for proper disposal as well as collect and burn off the methane gas that is produced as trash biodegrades. They hope to use this methane to create electricity or power city trucks in the near future. According to a supervisor there, given these safety methods, once a landfill is sealed, and even if the liners degrade, the remaining materials should be inert.

So how can we help this process?

Follow these General Waste Tips:

* Acceptable material for the "Grey Waste" bin include: plastics labeled number 3 to 7, Styrofoam, plastic bags, junk mail, magazines, telephone books, cereal boxes/flatboard, paper products, tin/steel food cans, ceramics, dishes, glassware, mirrors, and general household rubbish.  

* H-Power does accept some materials you may consider hazardous such as alkaline batteries, aerosol spray containers, and paint, motor oil, or liquids. They prefer you pour liquid out into a bag with kitty litter or newspaper to be absorbed. Do not send combustibles such as propane tanks. 

* Consult the bulky item monthly pick-up schedule for your neighborhood for items such as furniture or appliances.  

* Opala.org provides information of where you can drop off hazardous materials such as pesticides and propane or electronic waste such as computers and cell-phones.

What potential impact does reducing our residential waste have?  
The introduction of HPOWER is an achievement in waste reduction and alternative energy. And the management of waste at the landfill seems well planned and sustainable. With the information above and the information provided by Opala.org, residents can better assist in this process. That said, the fact remains that as an island we should work to lower the waste produced from our homes and businesses.

We should be careful not to be over comforted by the abilities of HPOWER to reduce our waste mass. The investment in upgrades to HPOWER comes at the exclusion of investment in other more-sustainable energy sources. Research elsewhere has shown waste-to-energy plants can create significant pollution. We should also be aware of the potential health hazards the landfill can cause for the shores and communities on West Oahu.

Overall, facing a growing population and a lack of understanding about waste, we can remain vigilant about what we accept, buy, reuse, and how we discard of it. Products may be burned or recycled, but we are still paying for the energy and natural resources it takes to make and move those products to and from Hawaii. For example, because single-use plastics labeled numbers 3-7 are of a lower quality material, it is currently more cost effective to burn them than sort and ship them for recycling. In turn, these wasted petroleum by-products (and some really dangerous chemicals) can end up in the ash sent to the landfill. What if we avoided buying these plastics in the first place?

During the Waste Challenge, we will address specific ways to reduce waste at home with tips on reuse, composting, and rethinking daily habits. Ultimately, it takes some work to move beyond the convenience-oriented thinking of our throw-away culture, but the potential rewards for the health of our island are worth it.



Archived Comments

Comments posted prior to adopting Facebook comments.

  1. Don't forget also that the persistent organic pollutants such as heavy metals are produced and spewed into the air by the incinerator, poisoning both people and the aina. It ends up in the air we breathe, the food we eat, and the water we drink, etc. . It never goes away and just works it's way up the food chain to higher and higher concentrations.

    We should all try and live simply so that others may simply live.

  2. Olin Lagon says:

    Wow this is a great overview! Thanks Rachel for putting this piece together.

  3. Joannie Pan says:

    Thank you for taking the time to write this, Rachel. This is really great. Over Thanksgiving I had a conversation with my mom about where the trash in the grey bins end up. Once we throw something out of our homes, it's easy to never think about them again. It just becomes trash in our minds. I hope that more people will read your post and take your the tips you share to heart. The Opala website is helpful! :)

  4. come to the makeke market at kapolei High school every Thursday at 300 till 630 .There are worm bins there and local produce.

  5. Out yesterday, here's the latest reporting on violations at the Landfill: http://www.civilbeat.com/articles/2011/11/30/14076-epa-orders-additional-safeguards-at-waimanalo-gulch-landfill/

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