Heritage Square Exchange

Heritage Square 2020

In 2019, Jefferson County Open Space (JCOS) received a proposal for a land exchange with Martin Marietta Materials (MMM). The amended HSE agreement includes the exchange of 64.02 acres of JCOS property for approximately 70 acres of MMM property. Martin Marietta will use the 64.02-acre parcel to expand the current Specification/Aggregate mine located on US 40, north of I-70. JCOS will use three parcels for open space and park purposes and will receive $14.5 million at closing for the purchase of 1,192 acres of properties adjacent to Mount Galbraith, Clear Creek Canyon, and Centennial Cone Parks.

January 2023 

JCOS Land Transfer Completed with MMM.

September 2022 

Rezoning unanimously recommended for approval by Jeffco Planning Commission and approved by Jeffco Board of County Commissioners.

November 2021

The first amendment to the Heritage Square land exchange agreement between JCOS and MMM was approved by the Board of County Commissioners.

March 2020

March 2019

Map depicting the Martin Marietta and Heritage Square Land Exchange

Frequently Asked Questions/Common Community Concerns

What are the visual or scenic impacts of the mine?
Concerns about these impacts while mining is occurring and after reclamation is complete.

JCOS shares this concern and will continue to analyze this. View some simulated images here and here

Here are two examples of concurrent reclamation:
Concurrent Reclamation Visual 2Concurrent Reclamation Visual 1

How will expanding the mine impact wildlife?
Concerns about wildlife, such as elk and deer, utilizing the 143-acre portion of Mathews/Winter Park north of I-70 that would be traded to MMM to expand the life of the mine if the exchange is approved.

JCOS will continue to work with Colorado Parks & Wildlife to evaluate the impact on wildlife and possible mitigation methods. When more information is available, it will be posted on this web page and be used in our overall evaluation of the Heritage Square Exchange (HSE) proposal. 

What controls are in place to address or limit dust, noise, and lighting from the mine?
Concerns about current levels and dealing with these impacts for a longer period of time if the exchange is approved.

The MMM mine, and all others in Colorado, are regulated by both the State of Colorado Department of Health and Environment (CDPHE), and the Department of Natural Resources Division of Reclamation and Mining Safety (DRMS). The MMM mine has operated for more than four decades with this oversight. If the HSE is approved, the mine would be expanded geographically, but not in its operations. 

What will be done to preserve or celebrate the history of Heritage Square?
Community interest in celebrating the history of the site.
The majority of the buildings at this site have already been removed. If the exchange goes through, JCOS would plan to sell this property (Parcel 5) for zoned uses. Zoned uses could include Commercial and Light Industrial (Business/Office Park, Retail, Restaurants, etc.) but specifically not Residential or Auto Dealerships. JCOS would sell based on proposals that best fit the site and surrounding areas, keeping historic celebration in mind. Proceeds from the sale would be specifically earmarked for future acquisitions and ultimately add to the preservation of additional open space and parkland.

If the HSE occurs, when will the mining operation be complete?
Interest/concern about how long mining will occur at this site. 

MMM says that the life of the mine, whether the HSE is approved or not, will continue for decades. If the HSE is approved, it will extend the duration of mining, the question is for how long, and that will be determined in part by market demand. JCOS understands the community’s wish to have this timeline better defined and will work with MMM to seek an order of magnitude estimate. When we have more information on this, it will be posted on this web page.

What are the mine reclamation requirements? Will the county have any responsibility for this if the exchange is approved?
Interest/concern that mine reclamation is completed at or above standards given visual impact concerns and location and that this is done at no cost to the county.

Mining reclamation is regulated by the State of Colorado DRMS, and all efforts at this site must meet their requirements. In our 2002 land exchange with Lafarge (MMM’s predecessor), JCOS required reclamation above the state standards in these areas: out of public view mining, bench backfilling, concurrent reclamation, and an enhanced revegetation plan. The City of Golden also approved additional reclamation standards in the zoning for the property (Lena Gulch Official Development Plan). Whether or not the HSE is approved, JCOS will only accept land that has met DRMS, Golden, and our own reclamation standards and will not accept any liability or incur any costs for mining activities or reclamation.

Submit Comments or Questions

Email us at [email protected] by April 10, 2020