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Zone 7 board discusses Chain of Lakes mining expansion

Company offers water infrastructure, trail in plans asking for deeper mining

A presentation at the Zone 7 Water Agency Board of Directors meeting last week gave those who missed last month's public comment deadline for the environmental review period another chance to share their feedback on the Chain of Lakes mining and reclamation project.

Cemex, the company that owns the 920-acre Eliot Quarry, wants to alter modification plans and mine 100 feet deeper in the Lake B area on the site's west side, which also contains a nearly 150-feet-deep sand and gravel mine pit, for a total depth of 250 feet.

Plans to alter mining operations in the unincorporated Chain of Lakes area between Livermore and Pleasanton include developing a future trail along Vineyard Avenue and building major water infrastructure at no additional cost to Zone 7.

The new reclamation plan also calls for some technical changes like keeping the Arroyo del Valle separate from Lake B -- which it currently flows through -- and raising the lake level containment by 14 feet to a total height of 369 feet, resulting in less water overflowing into the San Francisco Bay.

Cemex representatives said they hope to restore the Arroyo del Valle at Lake B around the year 2023 as well. They noted in project documents that the habitat's current state is "highly degraded," "choked with weeds," and "not suitable for protected fisheries." They also mentioned several public benefits tied to the plan like restoring the land to a "near-natural state" and developing a public trail on the south side along Vineyard Avenue.

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Arroyo Del Valle would be realigned south of its current spot and Cemex would abandon plans to renew mining in Lake A, which would be handed over to Zone 7 by 2023 for water management. Cemex plans to build a diversion structure there at no cost to the water agency when the transfer takes place.

Mining in both lakes would cease by 2056, under the proposal.

Geologists working on behalf of the company said new groundwater layers in the lake would not be exposed by any mining and did not detect any aquitards in the lake, which are areas in the Earth that restrict groundwater from flowing to other aquifers.

Residents who attended the meeting and board directors Sandy Figuers, Michelle Smith-McDonald and Olivia Sanwong peppered the company with questions for more details about the project's stability analysis, water quality data and monitoring nearby wells for water levels.

Tamara Reus from Friends of the Open Space and Vineyard commended the planned trail as a much-desired feature for the public during the meeting's open comment portion.

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"We're really encouraged to see those trails being included in this project; they've been promised for a long time and people are really wanting to use them," Reus said. "Ultimately I guess everything's turned over to you and want to make sure those will definitely be included as this goes forward and that you will maintain them if the property's turned over to you."

Zone 7 General Manager Valerie Pryor clarified the agency does not operate any recreational facilities and that while facilities such as trails "are compatible with our uses, we do coordinate with external agencies and then they fund and operate the recreational facility."

The Alameda County Community Development Agency, which issues permits for mining activity and reclamation plans on unincorporated land, is currently preparing an environmental impact report. Regulatory permits for the project could be issued within the next one to two years, according to Cemex.

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Zone 7 board discusses Chain of Lakes mining expansion

Company offers water infrastructure, trail in plans asking for deeper mining

by / Pleasanton Weekly

Uploaded: Tue, Aug 27, 2019, 6:26 pm
Updated: Wed, Sep 4, 2019, 11:55 am

A presentation at the Zone 7 Water Agency Board of Directors meeting last week gave those who missed last month's public comment deadline for the environmental review period another chance to share their feedback on the Chain of Lakes mining and reclamation project.

Cemex, the company that owns the 920-acre Eliot Quarry, wants to alter modification plans and mine 100 feet deeper in the Lake B area on the site's west side, which also contains a nearly 150-feet-deep sand and gravel mine pit, for a total depth of 250 feet.

Plans to alter mining operations in the unincorporated Chain of Lakes area between Livermore and Pleasanton include developing a future trail along Vineyard Avenue and building major water infrastructure at no additional cost to Zone 7.

The new reclamation plan also calls for some technical changes like keeping the Arroyo del Valle separate from Lake B -- which it currently flows through -- and raising the lake level containment by 14 feet to a total height of 369 feet, resulting in less water overflowing into the San Francisco Bay.

Cemex representatives said they hope to restore the Arroyo del Valle at Lake B around the year 2023 as well. They noted in project documents that the habitat's current state is "highly degraded," "choked with weeds," and "not suitable for protected fisheries." They also mentioned several public benefits tied to the plan like restoring the land to a "near-natural state" and developing a public trail on the south side along Vineyard Avenue.

Arroyo Del Valle would be realigned south of its current spot and Cemex would abandon plans to renew mining in Lake A, which would be handed over to Zone 7 by 2023 for water management. Cemex plans to build a diversion structure there at no cost to the water agency when the transfer takes place.

Mining in both lakes would cease by 2056, under the proposal.

Geologists working on behalf of the company said new groundwater layers in the lake would not be exposed by any mining and did not detect any aquitards in the lake, which are areas in the Earth that restrict groundwater from flowing to other aquifers.

Residents who attended the meeting and board directors Sandy Figuers, Michelle Smith-McDonald and Olivia Sanwong peppered the company with questions for more details about the project's stability analysis, water quality data and monitoring nearby wells for water levels.

Tamara Reus from Friends of the Open Space and Vineyard commended the planned trail as a much-desired feature for the public during the meeting's open comment portion.

"We're really encouraged to see those trails being included in this project; they've been promised for a long time and people are really wanting to use them," Reus said. "Ultimately I guess everything's turned over to you and want to make sure those will definitely be included as this goes forward and that you will maintain them if the property's turned over to you."

Zone 7 General Manager Valerie Pryor clarified the agency does not operate any recreational facilities and that while facilities such as trails "are compatible with our uses, we do coordinate with external agencies and then they fund and operate the recreational facility."

The Alameda County Community Development Agency, which issues permits for mining activity and reclamation plans on unincorporated land, is currently preparing an environmental impact report. Regulatory permits for the project could be issued within the next one to two years, according to Cemex.

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