Hawaii Grapples With Lofty Cesspool Replacement Goals

One new project combines an incinerating toilet and small onsite system for treating kitchen wastewater for residential use

Hawaii Grapples With Lofty Cesspool Replacement Goals

Stuart Coleman is executive director and co-founder of WAI.

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Hawaii plans to eliminate cesspools, and although that’s a big task, Wastewater Alternatives & Innovations sees this as a way to jump far ahead in the use of onsite technology. The organization put together a $30,000 system on the island of Kauai that uses a Cinderella incineration toilet from Norway to handle human waste, a small septic system for kitchen blackwater (graywater), and a mulch basin and seepage pit to treat bathroom graywater.

Stuart Coleman is executive director and co-founder of WAI, and is also a member of the state working group figuring out how to replace all those cesspools. The working group was created by the state Legislature in 2017 when it voted to eliminate all cesspools by 2050.

Pumper talked to Coleman and to Joachim “Joko” Schneider, a native of Germany who came to Hawaii to earn a master’s degree in civil engineering and for a time was WAI’s senior project coordinator. Before starting WAI, Coleman spent 11 years as the Hawaii manager of the Surfrider Foundation, a nonprofit that works to protect the oceans and access to them.

Pumper: How did WAI come into being?

Coleman: After the Legislature created the Cesspool Conversion Working Group, there were no nonprofits out there to help homeowners and counties and the state with the conversion plan. I realized somebody had to start a nonprofit. WAI started in January 2020, and we were quickly besieged by the pandemic. So we had to be really creative and think outside the box. We were able to bring on Joko from the University of Hawaii Sea Grant Program. (Sea grant programs are like the land-grant programs funded by the federal government. Both are charged with studying issues important to the citizens of a state.)

Pumper: How is the cesspool working group doing?

Coleman: I think we’ll wrap up (soon) and issue a report. A lot of people are waiting for that before they make their own plans for upgrading onsite systems. We were the last state to address cesspools, but if we go beyond septic systems and embrace new technology, we can be a national leader.

States that just converted from cesspools to septic along the coasts, especially the East Coast, are having to redo all of those systems and spend so much money, Suffolk County (New York) being one of the big ones. We use Suffolk County as a cautionary tale because their shellfish industry collapsed because of nutrient pollution.

We’re trying to bring in innovative technology because we live on islands, and we’re surrounded by water, and we need to take care of our coastal areas.

Pumper: Surfrider was part of the U.S. Supreme Court case in which the justices ruled that pollution seeping through the ground and into the ocean from wastewater injection wells was a violation of the Clean Water Act. Do you know how much pollution comes from cesspools in Hawaii?

Coleman: It’s calculated to be 53 million gallons of effluent going into our groundwater every day from these cesspools, which is larger than the worst sewage spill we’ve ever had in Hawaii.

Pumper: How did you choose the community of Kapa’a (on Kauai) as the place for this project?

Coleman: Kapa’a has a lot of cesspools, so it’s an area that needs to find solutions. And we knew Robert Zelkozsky, a former Surfrider volunteer and leader who lives there and wanted to try something.

Pumper: So the Cinderella toilet reduces the solids to ash, but what happens to the liquid waste?

Coleman: Liquids are evaporated and go up the exhaust stack. That’s the current downside. Even if people want to go No. 1, the toilet must incinerate that liquid and use electricity. We’re working with Cinderella to save electricity, maybe turn the urine into fertilizer.

Pumper: Did you consider a composting toilet to eliminate the electricity use?

Coleman: We are staying away from composting toilets because the Department of Health doesn’t like people dealing with their own waste. Composting toilets are great for some locations. But in suburban dwellings it’s too big a risk and too hard to monitor.

The county innovation grant that paid for this project also paid for us to install a Cinderella at a remote facility for the state Division of Forestry and Wildlife where there has been a composting toilet for years. For years, workers had to shovel out all of the waste and put it in metal drums. Then a helicopter would pick it up and fly it off for treatment, and that helicopter is minimum $5,000 per ride. Even to get the new toilet in there we’ll have to use a helicopter. But with the new incineration toilet, they won’t have to do that kind of work anymore.

Pumper: How much power does the Cinderella toilet use?

Schneider: It uses about 1 to 2 kilowatt-hours per incineration. If you have two people using it close to each other, their waste will be taken care of by the same incineration. If you have only one person going per hour, that’s going to be only one incineration.

Coleman: We’re saving the potable water, which is the main thing, which I think is going to become more of an issue going forward.

Pumper: Why is the wastewater from kitchen and bath separate?

Schneider: In Hawaii kitchen wastewater is considered blackwater. In Europe some countries consider it heavy graywater.

Pumper: How does graywater treatment work?

Schneider: There’s a 1,000-gallon plastic tank taking the kitchen sink and dishwasher wastewater. We’re hoping to move to a smaller tank for future installations. Water goes into a drainfield about 12 1/2 feet long and 6 feet wide with traffic-rated Infiltrator chambers.

The mulch basin is about 10 by 25 feet and 3 to 4 feet deep, and filled with wood chips leftover from landscaping. There are some plants on top of it, and they’ll use some water, but most of the water is intended to filter down to the aquifer. The seepage pit, a retrofitted cesspool, is only for overflow.

Coleman: Originally, we estimated needing a 200-gallon tank for the kitchen wastewater, and even that was oversized. But we also needed a tank certified by IAPMO (International Association of Plumbing & Mechanical Officials), and the smallest we could find was 1,000 gallons.

The size of the tank and overflow seepage pit means the system has a lot of redundancy, but it was still a success. The Zelkovskys are pleased with it. They’ll be saving lots of water and helping recharge the aquifer. And the water that does go out will be much, much cleaner than before.

Pumper: Are you looking at other projects?

Coleman: We want to do more graywater recycling. The more we can recycle, the better.

We have designs with Cinderella units inside homes and then three different nitrogen-reducing leach field designs [for graywater]. We’re [also] working with three companies on decentralized treatment for smaller communities. On those, we hope to be one of the first projects to do 100% recycling of liquids and solids.

Schneider: I think it’s important to note that the Kapa’a combination system is really exciting, but it’s not going to work for every house.

Coleman: Yeah, people are constantly asking, “What is the solution?” There’s not one solution. There are so many factors to consider on each site that we need to have as many options as possible.


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