Written by Liz Adams, Research Associate at the UNC Institute for the Environment

Could the Wake Stone Quarry (Triangle Quarry) and the proposed quarry expansion that borders Umstead State Park ever become a recreational amenity that would benefit the community? How much would the RDU and Wake Stone concept plan cost, and who would pay?

We know some answers on how much it would cost, both financially and in regards to the required environmental permits, from a study that the Town of Cary commissioned in 2013 by CH2MHILL to determine if water could be stored in the Triangle Quarry. It was one of 5 alternative options studied under a joint Cary-Apex-Morrisville Study to expand our public water supply. This option was not selected, as it was too costly and complex compared to withdrawing more water from Jordan Lake.

The cost for this option to fill the existing Wake Stone Quarry pit with water was estimated to be $178 million. We need to dig further to determine what this covers, but it is safe to say, that implementing concept plan by Wake Stone will be difficult and expensive. Wake Stone’s concept plan shows both quarry pits filled with water, the existing quarry pit, and the one on public land that will be leased from RDU Airport Authority.

The following section is quoted from this Cary-Apex-Morrisville Joint Water Supply Basin Planning study:

Option 4: Water Supply from Crabtree Creek with Storage in Existing Triangle Quarry

Raw water would be pumped from Crabtree Creek, stored in Wake Stone Corporation Triangle Quarry (CH2M HILL and Brown and Caldwell,2013, Figure 3), treated at a new WTP located nearby, and distributed through the existing water system.

The quarry has the potential to provide up to 4.6 billion gallons of raw water storage at the projected final excavated volume.

The State of North Carolina has the first right of refusal for the quarry parcel when the mining is complete, so the state would have to agree to relinquish that right to the property.

For this strategy, raw water would be withdrawn under operational guidelines based on thresholds for different withdrawal scenarios that could occur based on available flows in Crabtree Creek.

Based on these preliminary guidelines, an annual average safe yield of 10 mgd from Crabtree Creek is projected. During the summer peak demand months, up to 12 mgd could be provided from the quarry storage.

An environmental document meeting the State Environmental Policy Act (SEPA) requirements would be necessary for this strategy. There are several key issues which could affect the feasibility of this alternative including:

• Potential direct impacts of the water withdrawal, including maintaining minimum in stream flows to meet habitat and water quality requirements.
• The Crabtree Creek watershed has a Superfund site in the headwater area (Settlement Agreement for Ward Transformer Site, cost $80 Million for partial cleanup)

Is it ethical for RDU Airport Authority and Wake Stone to claim that an recreational amenity would be available to the community after the closure of the expanded Wake Stone Quarry without showing how this plan will be implemented, and at what cost?

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