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Henderson housing project is containment pathway for manganese mine

Cleanup could be coming soon to the Three Kids Mine as developers look to address arsenic and petroleum.
Carly Sauvageau
Carly Sauvageau
EnvironmentHousingLocal Government
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The Three Kids Mine, an abandoned manganese extraction site that was booming during both World Wars when the metal was used to strengthen steel, is a physical reminder of Henderson’s history as a town “born in America’s defense.” 

The mill’s foundation, bustling with workers from 1917 to 1961, is now graffitied and surrounded by sagebrush and a mix of man-made and untouched hillsides. 

But by early 2026, developer Lakemoor Ventures LLC plans to hold a grand opening for the first phase of a 3,000-unit housing project on land that includes the abandoned mine.

The $250 million project, which has spanned 16 years and four Henderson mayors, is being made possible with funding from private investors and incoming land sales from future homeowners of the development.

State law says that you can create a redevelopment zone if it's a gravel pit or an old abandoned mine … and use redevelopment monies to help with the funding,” Mindy Unger-Wadkins, the sister and business partner of Bob Unger who together make up Lakemoor Ventures LLC. 

This is not Unger’s first time funding a redevelopment project using this method. The developer, lawyer and previous lieutenant governor hopeful also used this funding method to develop an abandoned gravel pit into what is now the Tuscany Village neighborhood in Henderson. 

Because the federal government valued the Three Kids Mine property at less than what it would cost to clean it, the developers did not pay when acquiring the land.

Though some locals have said they are happy to see containment of the site, other people have expressed health concerns for future residents. 

“You're gambling with the health of residents that live nearby,” William Cappiello said at the Nov. 21 Henderson City Council meeting where members decided to move forward with the project. “And you're most likely going to lose, if not now, 20 to 30, 40 to 50 years down the road.” 

Another public commenter said cleaning up the site was essential to the health of nearby residents, noting that the Nevada Department of Environmental Protection (NDEP)  is monitoring the project.

Here’s a look at what is happening with the development site now:

The Three Kids Mine, a long abandoned open-pit manganese mine as seen in Henderson on Tuesday, October 4, 2023. (Daniel Clark/The Nevada Independent)

Henderson City Council vote

On Nov. 21, Henderson City Council approved the plans to sign off on a land transfer to Lakemoor Ventures LLC. Except for Mayor Michelle Romero, who was absent from the meeting, the four remaining council members voted unanimously in favor of the project.

Romero told The Nevada Independent during a Dec. 11 phone interview that if she had been present, she would have had to abstain from voting because Las Vegas Paving — where her husband is the safety director — is working on the project.

The day following the vote, the state and city sent a letter to the secretary of the interior agreeing to transfer the land to Lakemoor to develop. Now the secretary of the interior’s office needs to sign the agreement, which developers said they hope will happen by the end of January.

Cleanup and public reaction

Lakemoor Ventures LLC is working with Broadbent & Associates, an environmental consulting firm based in Henderson, and the NDEP to clean up the land before Pulte, one of the largest residential construction companies in the United States, begins construction. Unger-Wadkins said the cleanup should begin by March 2024.

The cleanup could take decades longer if it were put under the regulations of federal legislation.

“Better than us breathing in the dust whenever the wind blows,” Darryn Padfield, the founder of River Mountain Bike Shop near the Three Kids Mine site, told The Nevada Independent in a phone interview in October.
One Superfund site, the abandoned Anaconda Copper Mine in Lyon County’s Mason Valley that the Yerington Paiute Tribe has fought to get cleaned up for 30 years, was taken off the Environmental Protection Agency’s priority list by former Gov. Brian Sandoval. He later put the state and Atlantic Richfield Company (ARCO) in charge of the cleanup. The site is still being cleaned today.

The view from the bottom of Three Kids Mine, a long abandoned open-pit gypsum mine as seen in Henderson on Tuesday, October 4, 2023. (Daniel Clark/The Nevada Independent)

The Three Kids Mine site has hazardous materials including manganese, lead, petroleum and arsenic.

Developers said a significant portion of the cleanup will be remediating the tailings ponds. 

When the manganese mine was in operation, miners would extract manganese from other rocks by filling large silos with petroleum. The manganese would float to the top and be taken out before miners flushed the remaining fluid into the now 15-acre tailings area, the volume spreading to 1.6 million cubic yards that need to be addressed. 

These areas, which are the most affected by contaminants, will be excavated of affected dirt, which will be placed into the Hydro Pit. The railing in the Hydro Pit will be covered with an impermeable liner and a minimum of 2 feet of clean soil.

The Hydro Pit will also be part of the residential development’s recreation areas, rather than underneath housing. 

The 10-foot clean soil cover will be placed over other areas of the mine site after mine waste — such as tailings and waste rock — have been removed from those areas and placed into the pits. 

Asbestos and municipal solid waste from the surface of the mine site have been removed and disposed of at an offsite landfill. Houses may be built over most of the areas covered by 10 feet of clean soil.

Cleanup will also involve filling in the pits, one of which is around 300 feet deep, with waste rock — or rock that was moved during mining to get to manganese veins — mixed with contaminated soil before the entire site is covered with 10 feet of clean dirt retrieved from nearby hillsides. 

Another concern is arsenic and asbestos contamination into water and the air.

The Three Kids Mine, a long abandoned open-pit manganese mine as seen in Henderson on Tuesday, October 4, 2023. (Daniel Clark/The Nevada Independent)

High levels of arsenic have been found in drinking water in communities across the state, particularly in rural and tribal communities. The poisonous metalloid is naturally occurring across the earth’s surface but can be found in high levels in areas near mining. 

“We're absolutely concerned about arsenic,” said Kirk Stowers, the principal geologist and environmental division manager of Broadbent. “We're not concerned about arsenic in the groundwater.”

Stowers said the concern lies with air quality during cleanup.

“In terms of an external exposure standpoint, [air quality] is really the only thing that we're going to have to manage very closely,” he said. “After that material is in the pit and covered up and there's 10 feet of clean soil across this site, I mean, I would definitely live here and not be concerned about it.” 

He said the groundwater in the area is about 300 feet below the surface. Leaching reports by Broadbent showed that the deepest penetration of the contaminants only goes about 20 feet below the surface of the mine and this contamination happened when the mine was at its wettest during operation. 

Particles of arsenic and asbestos — which was dumped on the site and is not naturally occurring in the area— traveling in the air during cleanup is more of a concern than groundwater contamination, Stowers said.

He said the cleanup crew will keep the ground wet to mitigate dust when they are moving dirt.

The view from the bottom of Three Kids Mine, a long abandoned open-pit gypsum mine as seen in Henderson on Tuesday, October 4, 2023. (Daniel Clark/The Nevada Independent)

Nevadans living among mines

Nevada isn’t called the Silver State for nothing. Mining of various materials is part of the state’s past, present and future.

In Tonopah and Goldfield, residents live among the hundreds-of-feet-deep shafts, sprawling tailings and headframes left by mining companies over a century ago. 

The Yerington Paiute Tribe and the Walker River Paiute Tribe’s water source is being investigated by the Environmental Protection Agency to determine levels of contamination from the Anaconda Copper Mine in Yerington that potentially migrated into the Walker River. 

According to the Nevada Department of Conservation and Natural Resources, from Nevada’s birth as a state through the turn of the 20th century, few regulations existed to protect communities and ecosystems from mine pollution. 

It wasn’t until the 1989 legislative session that lawmakers required mines to have “cradle-to-grave oversight” of all mining operations through the NDEP’s Bureau of Mining Regulation and Reclamation, zero discharge into groundwater and containment systems for hazardous materials. 

This has left present-day Nevadans to clean up past residents’ large messes if they want to develop land near those sites. However, the Three Kids Mine left the land with no value to the federal government, giving developers a unique opportunity to acquire federal land at no cost.

“We are voluntarily cleaning up this site. We weren't the ones that made the mess. The manganese company that was out here for years is long gone, nobody's around … they didn't clean it up,” Ungers-Wadkins said.

Though the BLM has not signed the land transfer agreement yet, Unger-Wadkins and Stowers said all signs point to the federal agency moving forward with the project.

The Three Kids Mine, a long abandoned open-pit manganese mine as seen in Henderson on Tuesday, October 4, 2023. (Daniel Clark/The Nevada Independent)

“If [the land] is contaminated to such a point that it is useless to you, the government has a useless piece of property that they can't do anything with,” Stowers said. ”That's why they were willing to give it away because its liability is higher than its value.”

Though the development is welcomed as a way to clean up a site that could cause adverse health effects if untouched, others still say that housing may not be the best option for the land.

Dietrick McGinnis is the president and founder of McGinnis and Associates, an environmental consulting company based in Reno but that works on assessments statewide. He said redeveloping hazardous sites is common in Nevada but city leaders may want to think twice before developing the Three Kids Mine into a residential subdivision.

"A lot of Nevadans live near mines, but that was not always intentional. A lot of people bought homes and didn't realize they lived next to mines. And a lot of people living near mines did not recognize the risks of that until later on,” McGinnis said. 

“This may not be a good situation to perpetuate. Ask yourself what is best land use management. It may not include this particular property being developed for residential.”

Updated at 12 p.m. on 12/27/2023 to correct details about the remediation process.

Updated at 11:23 a.m. on 1/2/2024 to correct that former Gov. Brian Sandoval signed the transfer of the Anaconda Copper Mine site.

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