The PA AMR Conference Committee is proud to host a workshop this year sponsored by Cravotta Geochemical. The workshop is free of charge but If you would like to go, you will need to “purchase” a separate workshop registration from the registration page. Meals are not provided with this registration.
THE WORKSHOP WILL BE HELD ON THE SAME DAY AS THE TOUR, TUESDAY, OCT. 14TH. YOU WILL NOT BE ABLE TO GO TO BOTH.
PHREEQ-N-AMDTreat model to evaluate water-quality effects from passive and active treatment of mine drainage
Chuck Cravotta, Hydrologist/Geochemist, CGC; cravottageochemical@gmail.com
Brad Shultz, Mining Engineer, Kleinfelder; bshultz@kleinfelder.com
Agenda for Workshop (October 14, 2025, 12:00 pm – 5:00 pm):
12:00 pm Assistance with software installation and computer setup.
12:30 pm Overview of AMDTreat 6.0 Beta cost-analysis software (YouTube video)
1:00 pm Overview of PHREEQ-N-AMDTreat water-quality modeling tools including CausticTitration, ParallelTreatment, and TreatTrainMix2 (Power Point)
1:45 pm Live demonstrations of corresponding cost and water-quality models for
example passive and active treatment systems
2:30 pm Break
2:45 pm Live demonstrations of corresponding cost and water-quality models for
example passive and active treatment systems
3:30 pm Hands-on participant trials for provided case studies or their own AMD case
4:30 pm Group Questions and Answers and Adjourn
Abstract for Workshop:
AMDTreat 6.0 Beta (2022) is a newly updated computer application for estimating costs and sizing of facilities to abate acid mine drainage (AMD) through application of passive or active treatment technologies. The software has comprehensive cost-analysis modules for passive systems, including vertical flow pond, oxic or anoxic limestone drains, manganese removal bed, aerobic wetlands, and bioreactors, plus active systems, including caustic soda, soda ash, lime products, hydrogen peroxide, permanganate, polymer, and ancillary components such as decarbonation (aeration), conveyance channels, ponds, reaction tanks and clarifiers. The software provides over 400 user modifiable variables for excavation, construction, revegetation, piping, road construction, land acquisition, system maintenance, labor, water sampling, design, surveying, pumping, sludge removal, chemical consumption, and other functions. The default cost data can be modified to adjust for inflation or site-specific requirements. AMDTreat 6.0 also contains several financial and scientific tools to help select and plan treatment systems. These tools include a an acidity calculator, flow calculation tools for flumes and weirs, a mass-balance calculator, pH averaging tool, and an iron oxidation tool, plus an integrated version of the PHREEQ-N-AMDTreat “TreatTrainMix2” water-quality modeling tool (Cravotta, 2020, 2021). The integrated PHREEQ-N-AMDTreat tool incorporates all the other scientific tools into a single program to evaluate potential changes in pH, dissolved metals, and associated solute concentrations resulting through sequential steps of passive and active treatment of AMD.
The integrated PHREEQ-N-AMDTreat (TreatTrainMix2) tool and stand-alone PHREEQ-N-AMDTreat tool sets (CausticTitration.exe, ParallelTreatment.exe, and TreatTrainMix2.exe), which augment AMDTreat 6.0 Beta and are available as software downloads (Cravotta, 2020, 2022), utilize PHREEQC equilibrium (aqueous and surface speciation) and kinetics models for gas exchange, iron and manganese oxidation and precipitation, limestone dissolution, and organic carbon oxidation combined with reduction of nitrate, sulfate, and ferric iron. Reactions with caustic chemicals (CaO, Ca(OH)2, NaOH, Na2CO3) or oxidizing agents (H2O2) also may be simulated separately or combined with sequential kinetic steps. A user interface for each stand-alone tool facilitates input of water chemistry and flow data for one or two influent solutions and adjustment of system variables, such as gas-exchange kinetics, abiotic and biological contributions to iron oxidation kinetics, and limestone kinetic properties, without changing the basic PHREEQC coding. Similar adjustments to key variables can be made with the integrated tool. Graphical and tabular output indicates the changes in pH, specific conductance, total dissolved solids, alkalinity, net acidity, metals, and other solute concentrations of treated effluent plus the cumulative quantity of precipitated solids as a function of retention time or the amount of caustic (or oxidizing) agent added. By adjusting kinetic variables or chemical dosing, the effects of independent or sequential treatment steps that have different retention times (volume/flow rate), aeration rates, quantities of reactive solids, and temperatures can be simulated for the specified influent quality. The size (land area) of a treatment system can be estimated using reaction time estimates for each of the treatment system components considered in the PHREEQ-N-AMDTreat model. Given the estimated reaction time to achieve the desired effluent quality, the AMDTreat cost-analysis model may be used to compute the size for each system component and the corresponding costs for installation (capital) and annual operations and maintenance (O&M), with summary results for the net present value (NPV) of each treatment component and the system as a whole. Thus, various passive and/or active treatment strategies can be identified that could potentially achieve the desired effluent quality, but could require different land areas, equipment, and costs for construction and O&M.
References:
AMDTreat 6.0 Beta (2022) https://www.osmre.gov/programs/reclaiming-abandoned-mine-lands/amdtreat
Cravotta, C.A. III (2020) Interactive PHREEQ-N-AMDTreat water-quality modeling tools to evaluate performance and design of treatment systems for acid mine drainage (software download): U.S. Geological Survey Software Release (https://doi.org/10.5066/P9QEE3D5)
Cravotta, C.A. III (2021) Interactive PHREEQ-N-AMDTreat water-quality modeling tools to evaluate performance and design of treatment systems for acid mine drainage: Applied Geochemistry, v 126, 10845 (https://doi.org/10.1016/j.apgeochem.2020.104845)
Cravotta, C.A. III (2022) Interactive PHREEQ-N-AMDTreat+REYs water-quality modeling tools to evaluate potential attenuation of rare-earth elements and associated dissolved constituents by aqueous-solid equilibrium processes (software download): U.S. Geological Survey Software Release (https://doi.org/10.5066/P9M5QVK0)