Revegetation

Status: Active
Industry Partners:
ASARCO: Mission Mine
BHP Copper
Grupo Mexico: La Caridad Mine
KGHM: Carlota Copper
Resolution Copper Mine
Photo of 2 scientists writing down data and checking GPS coordinates on revegetatedwaste rock slope.

CESM’s revegetation cooperative was established in 2014 with three copper mining companies with sites across southern Arizona and has expanded to five companies in Arizona and Sonora Mexico. The specific objective of the revegetation cooperative is to identify below-ground biogeochemical indicators of ecosystem development as tools to be used by the mining industry to quantify revegetation/reclamation progress and to evaluate the impact of revegetation strategies including: the significance of capping material quality, the value of soil amendments, seeding methods and timing, and seed mix composition.

Reclamation success can be defined as the establishment of a quantity of plant cover (%) comparable to surrounding undisturbed areas with a plant community that is characterized by a diverse structure of native species (grasses, forbs, shrubs and trees). Revegetation goals are dependent on end-use objectives; however, all reclamation strategies aim to establish a stable ecosystem that facilitates carbon sequestration, dust control and prevention of water-driven erosion processes. We contend that a critical component of long-term revegetation success is progress in soil development of the below-ground substrate to progressively generate a plant-growth supporting material for sustainable ecosystem development.

We welcome new industry partners to join this research cooperative. Please contact us for additional information. The contract Scope of Work (SOW) can be found below.

Scope of Work

We propose to establish an Arizona Copper Mining Company – University of Arizona (UA) research collaboration. The goal is to leverage the experience and specific environmental concerns of distinct mining companies to evaluate the potential application of UA revegetation research results to active mining properties in Arizona. Specifically, UA research conducted over the past decade has focused on the revegetation of legacy mining sites in Arizona and northern Mexico. This research has generated a suite of biogeochemical indicators that we believe can be used to predict: the potential for revegetation success; the best plants suited for the site; and the minimum amount of amendment needed to achieve successful plant establishment following direct seeding into tailings materials. We acknowledge and embrace the fact that each participating company has distinct priorities and environmental constraints guiding the revegetation efforts or proposed revegetation efforts at their respective properties. The variable conditions include, but are not limited to, revegetation of both 1) waste rock and tailings, 2) materials with neutral and acidic pH, 3) materials with slope angles ranging from flat to 2.5:1, and 4) direct seeding vs. cap and seed strategies. The proposed collaboration will generate data to determine whether our biogeochemical indicators can be used by the mining industry to optimize revegetation strategies and minimize amendments (and thereby costs) required to obtain successful plant establishment. Revegetation is a promising strategy to control dust emissions from retired tailings piles and to return sites to a more natural appearance during mine closure proceedings, especially when mines are located on Forest Service land or near residential communities. We anticipate that the application of our current research metrics to the diverse revegetation efforts being implemented by the participating companies will help develop strategies to improve revegetation efficiency and reduce cost under a variety of environmental conditions.

Deliverables for participating industries:

  • Initial planning meeting: Each participating industry will identify the specific substrate (tailings vs waste rock) to be evaluated and the specific environmental parameters or revegetation strategies to be addressed.

  • Site and sample analysis: An annual site visit will be conducted to evaluate plant establishment (where applicable) and design the sample collection strategy to address the specific environmental variables identified in the initial planning meeting. A total of 50 samples will be collected from each property annually and analyzed with a uniform suite of biogeochemical tests. An annual report will be provided to each participating industry with soil analysis and site assessment results.

  • Comparative assessment of biogeochemical indicators: Results from participating properties will be compared and the value of each biogeochemical indicator as a predictor for revegetation potential/success under the specific conditions established at each property will be evaluated. The comparative analysis will be summarized in an annual report available to all participants.

  • Property specific progress report: If requested, an analysis of mine waste development as a plant supporting matrix will be conducted by evaluating vegetated and unvegetated materials. Plant establishment surveys can also be conducted on sites with variable years under vegetation to establish a metric of progress in plant community development. When applicable, a comparative assessment of matrix development and plant establishment under different treatments will be produced for a specific property.

Specific details of proposed collaboration

  • A CESM Legal Membership Contract is signed with each participating company, renewable every three years. An associated annual financial agreement is signed that designates 1) the start date for the designated project, 2) the specific research cooperative, and 3) the mine site associated with the research project. Companies can sign multiple financial agreements associated with a CESM membership agreement to establish research initiatives at multiple mine sites.  

  • A site evaluation and sample collection will occur once per year, renewable annually. Vegetated sites will be characterized according to plant cover, plant species diversity and root depth.

  • Each of the 50 substrate samples will be characterized using the following analyses: pH, Electrical conductivity (EC), particle size distribution, total carbon (TC), total nitrogen (TN), total organic carbon (TOC), total sulfur, neutrophilic bacterial plate counts (NHC), substrate net acid producing potential (NAPP), molecular biology detection of soil indicator bacterial populations (for nitrogen fixation and ammonia oxidation populations).

  • Fully operational CESM laboratory facilities and research personnel are currently available at the UA to support this collaboration.