Hawaii First Water

Archives for April 2017

Why Honolulu’s Pipes Keep Rupturing…

May 2017, Civil Beat, Courtney Teague.

When a 2-foot-wide, cast iron water main broke beneath the H-1 freeway in Kahala in January, workers had to dig a gaping hole nearly 20 feet deep, and repairs took several days. A nightmarish traffic backup ensued, and the Waialae Beach Park was temporarily closed.

Two months later on a sunny afternoon in nearby Palolo, residents stood in their driveways, watching water shoot out of Pakui Street from a broken 16-inch cast iron main. The plume could be seen for miles as it rained down on a house across the street.

Sheila Niderost pointed to white lines around the break that she said were painted about a month earlier when the pipe had previously burst.

A Water Main Breaks Almost Every Day On Oahu

Like many Palolo residents, Niderost’s home has been in the family for decades. She can recall several main breaks on Pakui Street, including one 20 years ago that damaged her car and flooded her house and yard. The road cracked down the middle, and boulders rolled off the Wilhelmina Rise hillside at the end of her street.

“That was the worst I’ve ever seen it,” she said.

While some cause a lot more trouble than others, ruptures occur almost every day somewhere along Oahu’s 2,100 miles of water pipes.

Oahu has more water main breaks than most mainland cities of similar size. Unique island factors like underground lava tubes and corrosive clay soils — along with an apparent longtime unwillingness to charge people the actual cost of delivering their fresh water — are often blamed.

Whatever the cause, Honolulu faces a mammoth challenge in upgrading its water infrastructure. The Board of Water Supply aims to replace 1 percent of all pipes in the system annually, which would cost an estimated $160 million each year in current dollars.

BWS is considering another multi-year rate increase to help pay for the work. Even after fees were raised from 2012 to 2016, Oahu water users pay less than what is needed to operate and maintain the water system, according to a University of Hawaii professor and engineering expert.

See the rest of the article here…

Water out of thin air? It can be done…

April: By J.D. Capelouto, Reuters

LONDON (Thomson Reuters Foundation) – People living in arid, drought-ridden areas may soon be able to get water straight from a source that’s all around them — the air, American researchers said Thursday.

Scientists have developed a box that can convert low-humidity air into water, producing several liters every 12 hours, they wrote in the journal Science.

“It takes water from the air and it captures it,” said Evelyn Wang, a mechanical engineer at the Massachusetts Institute of Technology (MIT) and co-author of the paper.

The technology could be “really great for remote areas where there’s really limited infrastructure”, she said.

The system, which is currently in the prototype phase, uses a material that resembles powdery sand to trap air in its tiny pores. When heated by the sun or another source, water molecules in the trapped air are released and condensed — essentially “pulling” the water out of the air, the scientists said.

A recent test on a roof at MIT confirmed that the system can produce about a glass of water every hour in 20 to 30 percent humidity.

Companies like Water-Gen and EcoloBlue already produce atmospheric water-generation units that create water from air. What is special about this new prototype, though, is that it can cultivate water in low-humidity environments using no energy, Wang said.

“It doesn’t have to be this complicated system that requires some kind refrigeration cycle,” she said in an interview with the Thomson Reuters Foundation.

An estimated one third of the world’s population lives in areas with low relative humidity, the scientists said. Areas going through droughts often experience dry air, but Wang said the new product could help them still get access to water.

“Now we can get to regions that really are pretty dry, arid regions,” she said. “We can provide them with a device, and they can use it pretty simply.”

The technology opens the door for what co-author Omar Yaghi called “personalized water”.

Yaghi, a chemistry professor at University of California, Berkeley, envisions a future where the water is produced off-grid for individual homes and possibly farms using the device.

“This application extends beyond drinking water and household purposes, off grid. It opens the way for use of (the technology) to water large regions as in agriculture.”

In the next few years, Wang said, the developers hope to find a way to reproduce the devices on a large scale and eventually create a formal product. The resulting device, she believes, will be relatively affordable and accessible.

(Reporting by J.D. Capelouto; editing by Alex Whiting.; Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, climate change, resilience, women’s rights, trafficking and property rights. Visit news.trust.org/climate)

As sea level rises, much of Honolulu and Waikiki vulnerable to groundwater inundation

(Apr 2017) New research from the University of Hawaiʻi at Mānoa reveals a large part of the the heavily urbanized area of Honolulu and Waikīkī is at risk of groundwater inundation—flooding that occurs as groundwater is lifted above the ground surface due to sea level rise. Shellie Habel, lead author of the study and doctoral student in the Department of Geology and Geophysics, School of Ocean and Earth Science and Technology (SOEST), and colleagues developed a computer model that combines ground elevation, groundwater location, monitoring data, estimates of tidal influence and numerical groundwater-flow modeling to simulate future flood scenarios in the urban core as sea level rises three feet, as is projected for this century under certain climate change scenarios.

“This flooding will threaten $5 billion of taxable real estate; flood nearly 30 miles of roadway; and impact pedestrians, commercial and recreation activities, tourism, transportation and infrastructure,” said Habel. “The flooding will occur regardless of seawall construction, and thus will require innovative planning and intensive engineering efforts to accommodate standing water in the streets.”

Current problems with inundation

construction trench in Waikiki

This construction trench in Waikīkī shows that the water table is nearly at the ground surface at high tide. (credit: UH Mānoa Coastal Geology Group)

Simulations of groundwater inundation chart

Simulations of groundwater inundation (blue) and narrow unsaturated space (yellow) today and considering sea level rise of approximately 1, 2 and 3 ft during an average spring (monthly maximum) tide stage. (credit: UH Mānoa Coastal Geology Group)

Surprisingly, the team of researchers also discovered 86 percent of active cesspools in the study area are likely currently inundated by groundwater. This suggests that cesspool effluent is now entering coastal groundwater and coastal environments in the study area. Sea level rise of approximately three feet would fully inundate 39 cesspools, introducing effluent at the ground surface where people work and live. This presents a serious health concern that will become progressively more serious as contaminated waters begin breaching the ground surface.

They also found that the water table is close to the ground surface—within two feet at high tide—in many places. This narrow unsaturated space means that groundwater inundation will become a serious concern well before the end of the century. When it rains and infiltration fills this space, it is a problem already.

“Waikīkī, the gateway of the state’s tourism industry, currently has such narrow unsaturated space that many construction projects working below the ground surface have to dewater the excavation before construction can begin,” said Habel.

Adaptation to future sea level rise

“Our findings suggest that coastal communities in Hawaiʻi and globally are exposed to complex groundwater flooding hazards associated with sea level rise in addition to the typical concerns of coastal erosion and wave overtopping,” said Chip Fletcher, professor of geology and geophysics, associate dean of SOEST and principal investigator on the study. “Groundwater inundation will require entirely unique adaptation methods if we are to continue to live in and develop the coastal zone. Coastal planners and community stakeholders will need to work with architects, engineers, geologists, ecologists, economists, hydrologists and other innovative thinkers in order to manage these problems.”

This study identified particular locations and infrastructure that will be vulnerable to future flooding and is a crucial first step towards addressing future challenges. The team of researchers hope to use this methodology to identify future flooding and at risk infrastructure in other locations, as well as assist in developing adaptation efforts among vulnerable coastal communities.

This work was funded by Hawaiʻi Department of Land and Natural Resources, the Honolulu Board of Water Supply, UH Sea Grant and and HKL Castle Foundation.