• An aerial view of the existing mine.
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“Our operation at the quarry will not change as a result of this exchange and the same things that govern those operations will continue to govern those operations.”

That was one of the messages Martin Marietta West Division President Abbott Lawrence had for the Jeffco residents who participated in the March 1 virtual community meeting about a proposal to rezone a 64.02 acre section of Matthews/Winters Park it is seeking to expand its aggregates mine into.

Abbott defined aggregates as “all the various sizes of rocks and sand used to make concrete asphalt as well as other products that range from base materials for building roads, large boulders for constructing dams and reservoirs.”

That aggregates mine, located on 283 acres off of US 40 near its intersection with I-70, opened in 1965.

Martin Marietta needs to secure permission to rezone that property for mining to complete a proposed exchange that involve giving Jeffco Open Space 130 acres of property, including the site of the former Heritage Square amusement park, in exchange for the right to mine the 64.02 acres.

Under the proposal, all of the land mined would be returned to Jefferson County once it has been mined and reclaimed with the county using it to create a large reservoir.

While that exchange has been on the table for months, the virtual community meeting presented one of the first times representatives from Martin Marietta have gone in front of the public to answer questions about the plan and what it will mean for those who live nearby.

MORE: Historic significance to Heritage Square land swap

“What’s going to happen here is Jeffco Open Space is going to receive four pieces of land that are valuable to Jefferson County and the open effort along with a trail easement and some cash overtime,” said Lawrence. “And Martin Marietta receives one piece of land that is not accessible to the public and to which Martin Marietta is uniquely able to ascribe value because of our desire to expand the spec-ag quarry.”

Noise, views among resident concerns

But while the proposal has been touted by both Jeffco Open Space and Martin Marietta as a win-win, residents still had questions about potential issues ranging from what impact the expansion of the mine would have on noise and views in the area to how long mining of the new parcel would take.

In answering those questions, Lawrence and two other Martin Marietta repeatedly returned to the theme that their company would utilize the same practices that it already utilizes at the existing mine and that the operations impacts on the community would not change.

Central to those practices, said, is Martin Marietta’s employment of a “mine from behind” technique that involves both trying to mine in such a way that it is kept out of the site of people outside the mine and reclaiming each portion of a mountainside that has been mined as soon as that mining is completed.

However, Lawrence acknowledged that mining from behind is not always possible and that there would be certain locations along I-70 from which mining operations might sometimes be visible.

“There are certainly angles from which you will be able to gain a perspective and see if there is nothing to block it,” said Lawrence. “But what we do know is we plan on mining to take as much advantage as possible of those natural barriers between the public and the mine.”

On the topic of blasting, Martin Marietta West Division Vice President David Hagerman said that mining is necessary to break rocks into smaller pieces, it is tightly-regulated.

“It’s nothing like you would imagine in the Old West movies,” he said. “It’s a very sophisticated process.”

According to Hagerman, the quarry seismographs and sound monitors that are used to record vibration and sound pressure 24/7.

“Quite frankly they are often triggered more by the wind than they are by blasting activity,” he said.

Sound is also mitigated through the use by various mechanisms, including a rubber cover that is placed around the mines’ main crusher to mitigate sound, Lawrence said.

As for the ultimate duration of mining activities, Lawrence said an exact answer is difficult to provide because it would depend on demand for aggregates and the exact mining makeup of the land discovered once mining starts.

However, he said Martin Marietta’s best estimate is that it will take two to three decades to fully mine out the site.

The community meeting is the first step in the formal rezoning process, which will ultimately involve a view of the proposal by the Jeffco Planning Commission and county commissioners with the latter group making the final decision.

While members of the public were asked to focus on asking questions rather than making comments, one commenter expressed a desire for there to be another community meeting where opponents could present their opposition.

Jeffco Planner Justin Montgomery responded that citizens would have the opportunity to formally express opposition at the planning commission and commissioner’s meetings where the rezone is formally considered. However, he also suggested that residents wanting to make comments in the form of emails that can be sent to pzweb@co.jefferson.co.us.

“Written correspondence is best because then we can provide that to our decision-makers in the case packets,” Montgomery said.