Potential Hydrologic Impacts of Lithium Extraction

This table applies to the resource types and extraction methods listed below.

What is known about surface-water conditions prior to land disturbance and extraction activities?

This subsection applies to the following resource types, extraction methods, and surface-water features.

1. Have surface-water features in the project area been adequately identified and characterized?

a. If yes, characterization and monitoring efforts should continue.
b. If no, a surface-water survey should be conducted, inventory created, and features characterized.

2. What is the location of each surface-water feature with respect to project boundary and facility activities?

a. If the surface water is within the proposed/permitted project boundary, downstream/downgradient, or upstream and hydraulically connected, there should be high consideration for potential impacts.
b. If no hydraulic connection and upstream of the project area, or at a distance/location outside of hydrologic area of influence (HAI), less consideration for potential impacts.

3. Is flow perennial, intermittent, or ephemeral and what are the sources of water?

a. If flow is perennial (continuous flow year-round) or intermittent (continuous flow during certain times of the year) with baseflow contribution from local groundwater (directly from the aquifer or from seep/spring discharge), high consideration for potential impacts.
b. If flow is ephemeral (flowing or pooling only in response to precipitation), there is lower potential for impacts. It is important to note that there is not always a clear distinction between flow classifications (i.e., perennial, intermittent, ephemeral) or the classification may change over time. For example, a drainage that has ephemeral flow during drought conditions may have intermittent flow during wet cycles.
c. If geothermally heated springs are present that support sensitive aquatic habitat, additional considerations should be made, including comprehensive hydrologic and hydrogeologic field assessments and the development of numerical models to quantify the expected hydrologic impacts.

4. Have surface-water quantity and quality baseline conditions been established (i.e., flow, stage, temperature, physical parameters, geochemistry) for average, dry, and wet conditions over multi-year, annual, and seasonal timescales?

a. If yes, monitoring should continue through all pre-extraction, extraction, and post-extraction periods.
b. If no, a monitoring program should be designed and implemented to define the natural range of variability of all hydrologic baseline parameters on all necessary timescales.

5. Do the surface-water features support groundwater dependent ecosystems (GDEs) (i.e., wetlands, riparian zones, seeps, springs)? Do any GDEs provide habitat for protected species, endemic species, etc.?

a. If yes to either of these questions, additional considerations should be made with respect to hydrologic impacts on ecosystem health. This should be considered during all monitoring and mitigation phases.
b. If no GDEs or protected species, monitor for the development of GDEs.

This subsection applies to the following resource types, extraction methods, and surface-water features.

1. For all facilities and land disturbances: What is the type, quantity, area (i.e., footprint), depth (if applicable), and location? To what degree will existing facilities be used?

a. If there is no existing infrastructure or facilities at the proposed extraction site, then there is a relatively high potential for hydrologic impacts.
b.If existing facilities will be used exclusively and no new facilities or modifications to existing facilities are required, there is less potential for hydrologic impacts.

2. For all facilities and land disturbances: What is the proximity of the disturbance/facility to surface water? Do they intersect surface waters? Are they located upstream of surface waters?

a. If yes to any of the above, assess possible impacts on surface water caused by erosion, sedimentation, or alterations to runoff. This may lead to the degradation or loss of the surface-water resource if facilities directly intersect it.
b. If disturbances influence surface water, alterations to runoff as well as increased erosion and sedimentation may result in degradation of local or downstream surface water.
c. If no, erosion and sedimentation may still increase depending on the scale of disturbance and the proximity to surface water.

3. For all facilities and land disturbances: Are best management practices (BMPs) in place for runoff and erosion control?

a. If yes, are they adequately designed to mitigate erosion, sediment transport, and deposition during a high-magnitude design storm, such as a 100-year flood frequency event? Were the following considered when selecting BMPs: infrastructure size, range of rainfall amounts (i.e., average, high), discharge rate and volume, type of discharge (e.g., potential for contaminated flow), and proximity to downstream surface waters? Runoff/stormwater diversions may impact inflows to downstream water resources.
b. If no, then erosion may lead to increased sedimentation in surface waters during flow events. Surface-water runoff amount and flow paths may change, impacting inflows to downgradient surface waters. Depending on the type of on-site facilities, this may also result in the release of harmful constituents into the environment.

4. Are wells to be installed for groundwater pumping and/or monitoring?

a. If yes, what drilling methods and drilling fluids will be used? What material will be used for well construction (i.e., bentonite, cement, etc.)? Is there potential for the release of harmful chemicals into the aquifer during construction? Will hydrostratigraphic units be sealed or packed to limit mixing between aquifers? Will the well head and annular space be sealed to ensure the well does not act as a conduit for surface water/contaminants to enter the subsurface? If acids are used during well rehabilitation at any point during the life of the project, additional consideration should be given to assessing impacts on water quality.

5. Will any artificial surface depressions be constructed (i.e., ponds, rapid infiltration basins [RIBs])?

a. If yes, how many process ponds and RIBs will be constructed and what are the dimensions of each? Determine the proximity of RIBs and ponds to surface water and groundwater and controls to prevent infiltration, such as liners. What is the area and volume per pond? Will artificial depressions capture precipitation during storm events or impact local runoff?

6. Will tailings or waste rock be produced during extraction activities?

a. If yes, what is the material? What is the design and dimensions of storage facilities? What is the proximity of the storage facility to surface water and groundwater? What controls are in place to prevent infiltration and contamination, such as liners. How will slopes be constructed?

What are the hydrologic effects of brine and freshwater extraction and facility operation?

This subsection applies to the following resource types, extraction methods, and surface-water features.

Groundwater and surface-water responses to groundwater extraction (evaluate for short and long-term cumulative impacts):

1. What are the expected hydrologic impacts on water quality and quantity associated with groundwater extraction, including brines and freshwater?

a. If expected hydrologic impacts are established with high confidence, take the necessary precautions based on these expectations (i.e., mitigation plan if impacts are expected).
b. If potential hydrologic impacts associated with extraction have not been assessed, see remaining questions in this section.

2. Has a hydrogeologic conceptual model (HCM) been developed?

a. If yes, use the HCM to make inferences about potential hydrologic impacts by considering the remaining questions in this section.
b. If no, develop an HCM and then consider the remaining questions in this section.

3. Has the hydrologic area of influence (HAI) associated with brine and groundwater extraction been established?

a. If yes, apply it when answering the following questions.
b. If no, establish the HAI considering the number, location, area, design, and pumping schedule of all pumping wells, each well’s depth and screened interval, aquifer(s) targeted, and groundwater conditions.

4. Is the brine/freshwater pumping schedule known (i.e., the volume extracted over time)?

a. If yes, does pumping occur year-round, seasonally, etc., and how might this affect water resources at these timescales?
b. If yes, what volume of brine and freshwater is extracted per year and how does this impact the annual groundwater budget, perennial yield, etc.?
c. If yes, what are the cumulative impacts of all pumping wells for the project plus other pumping wells in the basin to water resources, aquatic ecosystems, other water users/water rights? Consider potential water-quality and -quantity impacts for surface waters and groundwaters over short- and long-term scales.
d. If no, consider conservative pumping assumptions (quantities and time scales on the high end) until data are available.

5. Will groundwater and brine extraction alter the natural hydraulic gradients and groundwater flow directions? Note: If pumps are used, hydraulic gradients are always impacted because of induced hydraulic head changes in the aquifer.

a. If yes, to what extent will the gradients and flow direction be altered? How will water quality change in response to altered sediment-fluid interactions? How long until brine/water levels and quality recover in the pumped aquifer(s)?

6. Is the target aquifer hydraulically connected to adjacent aquifers?

a. If yes, how will it impact the water quality and quantity of the adjacent aquifer? How much mixing is anticipated? Is a mitigation plan in place?
b. If no, will the aquifer be fully replenished and over what time frame? What is the expected annual recharge/inflow rate to the aquifer?

7. Are any impacted aquifers hydraulically connected to surface waters?

a. If yes, are there any groundwater dependent ecosystems or special-status species? Is a mitigation plan in place?
b. If yes, what are potential water-quality and -quantity impacts? Is a mitigation plan in place?
c. If no, continue monitoring surface waters to validate the conceptual model and confirm no impacts on surface waters.

8. Is there potential for land subsidence to occur as a result of pumping? Pumping rates should be considered, as well as lithology of the pumped aquifer(s).

a. After or during pumping, if the strength of the aquifer material is less than the pressure of the overburden, there may be potential for the aquifer compaction.

9. Is freshwater being used for operations (e.g., dust or fire suppression, soil desalination, mixing with brines)?

a. If yes, how might freshwater applications impact surface-water and groundwater quality/quantity? Are best management practices in place to prevent discharged water from pooling or flowing on the land surface?

What are the hydrologic impacts of lithium-brine processing using evaporative concentration techniques?

This subsection applies to the following resource types, extraction methods, and surface-water features.

Water-quality considerations:

1. Once the brine has been extracted from the subsurface, will additives be used during the evaporative concentration process to precipitate unwanted ions/salts and create a concentrated lithium brine?

a. If yes, what are the specific additives used and quantities applied, and at which stage/pond? Will acids and bases be used to control pH at various stages? What are the on-site facilities and best management practices (BMPs) for additive storage?

2. Will any solid waste or by-products be produced during the evaporative concentration process?

a. If yes, will mineral compounds be precipitated from the brine (e.g., halite, sylvite, calcite, gypsum)? If so, in what sequence (at which stage/pond) and at what rate? How are solid waste and by-products stored, treated, and transported? For example, will precipitated material be dredged from the pond and transported to stockpiles or a sludge-containment reservoir?

3. Are there measures in place to reduce leakage and detect leakage from the evaporation pond into the subsurface?

a. If leakage reduction relies on low-permeability soils beneath and surrounding the pond, has a soil survey been conducted? Is a continuous low-permeability layer present beneath the pond and if so, what is the depth to the top of the layer and its thickness? How are any permeable soil zones managed (e.g., replaced with low permeability clays)?
b. If pond liners are used, what kind of material is used (Hypalon, polyvinyl chloride, polypropylene)? How are strips combined/sealed (e.g., adhesive, welding)? Are all liners leak-checked prior to use? Is a leak detection system co-installed with the liner?
c. Are precipitated salts used to reinforce the pond floor/walls?
d. What measures are taken to monitor for leaks in the subsurface (i.e., conductivity, temperature, and/or moisture sensors; piezometers)? If a leak is detected, is an action plan in place to find and repair the leak?

4. Are any additional processes used to augment the evaporative concentration process that could impact water quality directly or indirectly?

a. If yes, what are the techniques, what materials/additives are needed? For example, the use of alumina columns for selective adsorption or co-precipitation of lithium.

5. Is the transfer of brines between ponds driven by pumps?

a. If yes, how are pumps powered (e.g., diesel generators)? What BMPs are in place for all fuel storage, conveyance, etc.?
b. If no, does the method of transfer (e.g., gravity or another technique) pose risk for surface or groundwater contamination?

6. Will lithium-depleted brine be returned to the subsurface via reinjection wells or rapid infiltration basins (RIBs)?

a. If yes, how will the lithium-depleted brine be conveyed to the RIBs/injection wells (e.g., gravity fed or pumped through pipeline)?
b. If yes, will the proposed technique return the lithium-depleted brine to the source aquifer or a different aquifer? A great potential hazard is posed if fluid originally from a brine aquifer is infiltrated or injected into a freshwater aquifer.
c. If yes, how does the water quality of the return brine compare to the quality of the aquifer fluid? If RIBs are used, has an assessment of shallow water quality been conducted? Has geochemical characterization of the sediment in the unsaturated and saturated zones been performed?

7. Upon completion of the evaporative concentration process, is the lithium-concentrated brine refined on-site?

a. If yes, what additives, acids, etc., and procedures are used to produce the final lithium product? What are the BMPs in place for storing, transporting, and using these materials to prevent spills, contamination, etc.? Additives may include chemicals, acids, and bases that could degrade water quality if there is an environmental release.
b. If no, the lithium-concentrated brine is transferred for off-site processing. What BMPs are in place for transporting the brine? Is the brine transferred via a pipeline using pumps, trucked, shipped by railroad? What is used to power any pumps (e.g., diesel generators)?

8. Post-refinement, is any slurry or filtrate returned to the solar pond for further processing for lithium (or other materials of interest)?

a. If yes, what methods will be used to convey/transport these materials and what are potential threats to water quality?
b. If yes, the evaluation process should recommence at Section 5.4.1 #1.Water-quantity considerations:

9. Will water from the brine be removed through evaporation?

a. If yes, what volumes of brine and freshwater are consumed through evaporation and for extraction operations over varying time frames (seasonal, annual, life of the project). What percent of the total volume extracted is lost to evaporation? How many ponds are used, what are the pond dimensions, how much brine per pond, and what are the evaporation rates per pond? How do seasonal differences between evaporation and precipitation rates impact processing timing, duration, and total water loss? Are any steps taken to reduce evaporation or recapture evaporated water? What is the initial lithium concentration of the extracted brine and how is this concentration expected to change over time? How do lithium concentrations relate to the extracted brine volume (and volume evaporated)?

10. Will lithium-depleted brine be returned to the subsurface via reinjection wells or RIBs?

a. If yes, what is the anticipated volume of brine, treated water, etc., infiltrated (through RIBs) or reinjected (through wells) into the subsurface? What percentage of the volume pumped from the brine aquifer is returned to the aquifer? Reinjecting or infiltrating brines/waters result in a temporary and localized increase in water pressure, or groundwater “mounding,” that will alter natural groundwater flow paths. If brine is returned to a shallow aquifer that is connected to surface water, will surface-water flow/stage be impacted? Could this have an impact on groundwater dependent ecosystem, special-status species, or other water users/water rights holders?

11. Is freshwater needed during processing?

a. If yes, how much freshwater is needed during processing and what is the source of the freshwater? For example, freshwater may be used during refinement to prevent salts from crystallizing. If water is sourced from local freshwater aquifers, what are the hydrologic impacts (see Sections 5.3.1 #4 and #5).

This subsection applies to the following resource types, extraction methods, and surface-water features.

1. Will surface conditions (e.g., topography, grade, soil, vegetation) be restored to pre-extraction conditions?

a. If yes, over what time frame?
b. If yes, what are the best management practices to reduce impacts on erosion, stormwater, and sedimentation as facilities are deconstructed and removed and the land is regraded?
c. If yes, when will revegetation to pre-extraction levels be achieved? Prior to vegetation regrowth and root development, soil stability may be compromised. Erosion from wind and water, as well as slope failure can result in sedimentation of surface waters. Pre-extraction evapotranspiration rates may not be achieved until vegetation is fully grown. How will this impact the local and regional water balance, surface-water flow, etc.?
d. If no, where will land-surface conditions not be restored? What are the short- and long-term hydrologic effects of not returning these areas to pre-extraction conditions (i.e., runoff, erosion, and sedimentation)? What about impacts on excavated areas, such as groundwater/surface water interaction at a pit lake?

2. Will subsurface conditions (e.g., groundwater levels and flow paths, water chemistry, soils) be restored to pre-extraction conditions

a. If yes, how will this be achieved? Will pumping wells be plugged and abandoned to prevent surface contaminants from migrating downward through the well/borehole? If a surface mine required dewatering, will water levels completely recover? How long after pumping stops will water levels rebound?
b. If no, what will be the long-term consequences for water resources?

3. Will excavated areas be backfilled?

a. If yes, what are the methods to backfill surface depressions? Will the original rock/soil/sediment be used for backfilling? If the original stratigraphy is altered, how will the presence of homogenized/disturbed rock and soil impact soil physics, water infiltration, groundwater levels, and surface-water discharge?
b. If yes, has the original geologic material been exposed to the atmosphere? The material may be oxidized, which can change geochemical conditions. How might this impact water quality as water percolates through the disturbed rock or soil? Focus should be put on increased potential for leaching metals, acid mine drainage, and impacts on hydraulically connected surface-water bodies. Geochemical models can be developed to predict long-term effects to water quality associated with water-rock interaction.
c. If no, what are the geochemical implications to surface water and groundwater of not restoring these areas and leaving them exposed to the atmosphere, precipitation, etc.?
d. Are surface water and groundwater being monitored for water-quality and quantity impacts during closure? What is the hydraulic connectivity between areas used for ponds, rapid infiltration basins, tailings, excavation/backfill and surface-water and groundwater systems? Impacts on groundwater and surface water may be the result of delayed impacts of extraction activities or directly related to closure activities (e.g., regrading). Aquifer hydraulic properties may cause delayed groundwater and surface-water impacts, such as aquifers with low hydraulic conductivity that promote long residence times.

This subsection applies to the following resource types, extraction methods, and surface-water features.

1. Once the lithium extraction site has been reclaimed, will surface-water and groundwater monitoring continue to identify any long-term impacts?

a. If yes, will data collection be adequate to identify any long-term or delayed effects to surface water and groundwater from extraction activities (e.g., resource extraction, processing) and closure activities (e.g., restoration, reclamation)? What type of monitoring will be performed (i.e., groundwater/surface water quantity/quality)? What is the duration and frequency of data collection? Is monitoring adequate to identify any unexpected chemical releases into the environment (e.g., leakage through lined facilities)?
b. If yes and there was an open-pit mine, will a pit lake remain on-site? If yes, see pit-lake guidance in Section 5.3.2 #5.
c. If no, a surface-water and groundwater monitoring plan should be developed that addresses potential impacts on long-term surface-water and groundwater quantity and quality.

2. Will the physical stability of tailings and mine slopes be monitored? Will this be coupled with groundwater seepage monitoring

a. Assess stability by evaluating the slope angle and the internal mass strength. What is the factor of safety to prevent failure?
b. If surface mining, are caps and covers (such as on tailings) adequately designed for the current climate and for climate change scenarios with increased extreme weather intensity and frequency?
c. If no, a monitoring plan should be developed. Slope failure will have significant consequences for erosion and sedimentation, as well as containment of pollutants.

3. Will the long-term environmental geochemistry be evaluated and managed?

a. If yes, what is the potential for negative changes in geochemistry over time, such as the development of an oxidizing environment, materials that exceed their acid-buffering capacity, or hydrothermal alterations?
b. If yes, will numerical models predict contaminant fate and transport for a range of conditions that address uncertainties? Does it have a sufficiently long period of prediction?
c. If yes, will monitoring be conducted at observation points (surface water or wells) to verify or inform predicted concentrations, timing, and extent, which can be used to calibrate and update performance predictions?
d. If yes, will remediation occur if concentrations exceed predetermined thresholds? What will remediation entail?
e. If no, considering developing a geochemical modeling and monitoring plan. A numerical model can be developed to predict contaminant transport and fate. Monitoring plans are useful to verify or update the geochemical model.