1.6 Environmental Effects ~ Raquel

Silica Sand Mining operations have been monitored at other sites to better understand the direct and indirect impacts that the process may have on the environment. Using prior information, the preparers have been able to better determine their significance, specifically regarding the effects on nearby water supplies and how they will, in particular, affect both human and natural health in surrounding environments. A significant change in current environmental conditions caused by the activities proposed by the mine may result in further scoping and mitigations measures to be initiated if the project were to continue (DOE).

Physical Impacts on Water Resources

Nearby water sources could be heavily impacted by dust and debris from mining activity. According to Figure 1.6.1., the site is closely bordered by the Minnesota River (the solid line shown below) as well as its tributaries (shown as dotted lines below).

Figure 1.6.1. The black outline in the Figure above represents the proposed silica sand mind site and the nearby water bodies, which could be affected.

The intended site for the Project Area is located in the Middle Minnesota River Watershed. This natural feature is one of the twelve major watersheds of the Minnesota River Basin and is located in south central Minnesota within Blue Earth, Brown, Cottonwood, Le Sueur, Nicollet, Redwood, Renville, Sibley, and Watonwan counties. Twenty municipalities (of which Mankato is the biggest) are found within the approximately 862,060 acres of land that the Middle Minnesota River Watershed contains. Within the major watershed exist 104 minor watersheds, all

ranging from 1,297 to 28,760 acres in size. In all totality, agricultural land use is predominant in this portion of land (MRBDC, n.d.).

For a list of all the minor watershed identification numbers and included brief descriptions, please visit http://mrbdc.mnsu.edu/major/midminn/descminor28 for more information.

Both the surrounding Minnesota River and Minneopa Creek are deemed “impaired waters” by the Minnesota Pollution Control Agency due to the rivers’ failures to meet Total Maximum Daily Load (TMDL) standards (MPCA, 2013).

Figure 1.6.2. This map highlights the nearby-impaired waters as issued by the MPCA. The Project Area is enclosed in a black border.

The Mining Process

There are many steps within the silica mining process that may affect water quality and should be tested to determine the extent. “Prior to any actual mining being done at a site, it is necessary to remove overburden from the top of the sand formation” (WI DNR, 2012). The removal of overburden, which contains topsoil or subsoil that is largely composed of silt, loam, or clay, is scrapped off the surface and then hauled away in trucks. The excess dust and mineral content could affect nearby wetlands and streams / rivers and cause potential sediment buildup. Because of the varied composition that overburden is composed of, there may not be a particular way to

prevent the various sized particles from entering the nearby water supply. Some particles, specifically relating to clays, may be less than 0.002 micrometers in size, and could affect ion exchange and pH for the nearby Minnesota River.

As the overburden is hauled to the perimeter of whatever section of land is being mined, berms are formed, which would allot for a change in catchment and erosion, specifically when the site to be mined is nearest the surrounding wetland. In the Northeast quarter of our site is a moraine depression, characterized by an irregular mass of un-stratified glacier – formed boulders, gravel, sands, and clay. Because of the loosely held material makeup of this adjacent section to the proposed mine location, leaching of contaminated rainwater would most likely be a concern in this area as it connects to one of the only nearby wetlands in the vicinity, characterized as a shallow marsh (WI DNR, 2012). For more information, please see the maps below:

Figure 1.6.3. The map above represents the geomorphic description of the landscape. On the adjacent edge to the northeast corner lies the moraine depression in question, where a portion of the marshes reside.

Figure 1.6.4. The map above represents the different wetland types that exist in the area and could be affected by water catchment from the berms on the mine site.

A marsh is categorized by a frequently or continually inundated wetland with included emergent herbaceous vegetation adapted to saturated soil conditions. This definition aids in the understanding that standing water if often found on location and could become easily contaminated due to its down gradient location from the proposed mine site. The berms created by the mining process would only expedite the contamination of excess sediment due to the creation of a new catchment (characterized by steeps slopes and a rise in “artificial” topography) alongside the current, naturally formed depression found on the other side of the Northeast corner of the site in question. Beyond the depression where the shallow marshes are formed are more outwash deltas, which would easily aid in the flow of possible contaminants to the Minnesota River (Mitsch & Gosselink, 2007).

According to the Minnesota Department of Natural Resources, Shallow Marshes are classified as Type 3 wetlands, which are protected by Minnesota State law. It is imperative that the existing hydrology and geomorphology are kept intact as to prevent issues if contamination or physical disruption was to ever occur in excess

amounts. Further along, and closer to the Minnesota River in itself, are deep marshes, which have many of the same characteristics as shallow marshes, with simply greater water depths for more of the year, are also protected as Type 4 wetlands (MN DNR, 2014).

In their existing state, wetlands serve as natural filters and preventers of erosion in regards to the health of the Minnesota River. As per the proposed project description aforementioned, it is imperative that the current states of these wetlands remain intact as to provide a lesser chance of any leachates or soil contaminants from heading downstream.

Because the landscape in question is placed higher than the adjacent wetland, groundwater inputs to the wetland could be affected, which would subsequently result in a change in hydrology / geomorphology and further affect the particular wetland’s structure and function. A detailed analysis would need to be performed if the project was to continue so that assurance could be made that the nearby-protected wetlands would have as little damage as possible.

To prevent excess erosion and subsequent off – site contamination, the silica sand mine would be advised to seed and mulch overburdens once they have reached their highest elevation. This would aid not only in aesthetic and natural environment conditions, but provide for wind breakage on behalf of the nearby mine so that dust is not as readily able to escape into the atmosphere. Furthermore, these overburdens can act as barriers to screen light and sound pollution if the mine were to operate into the dark.

Once the overburden has been removed from the mine site, sand could then be excavated. Depending on the soil type in the area, different methods of silica sand removal would then have to be initiated – all with different impeding environmental effects therein associated.

The soil particle size that dominates the area is considered a silty and coarse, whilst the bedrock depth throughout the area is unknown. The proposed plan of action is to mine 50 – 80 feet into the surface of the earth, and if the bedrock is too close to the surface, that would cause for blasting of the substrate to occur. This is a risk that has been identified and would need further analysis to determine whether or not it would be of major significance. However, blasting it of itself releases much more contamination into the air and onto surrounding landscape. Based upon the silty and coarse composition (see Figure 1.6.5.) as a benefit however, more air space would allow for ease of equipment access to the sand. In brief, the positives versus the negatives of unknown bedrock depth versus ease of soil – makeup would need to be considered. Once the silica sand has been collected, processing would latter take place at another facility (WI DNR, 2012).

Figure 1.6.5. The entirety of the site in consideration contains a silty coarse soil, which would work well for equipment to mine.

Figure 1.6.6. The bedrock depth is unknown for the entirety of the landscape.

The Minnesota River

Although the Minnesota River is not connected directly to the site in question, enough depression in the landscape allots the edge of the proposed site to form a catchment boundary, which would allow for rainfall, groundwater, and surface water to have a passageway into the river. This could equate to excess sediment and contaminant buildup that would make its way along the current.

The Minnesota River and Floodplain offers a plethora of food and habitat for many types of wildlife species. Habitats that border and/or utilize the waters include woodlands, wetlands, bluffs, and riverine ecosystems where species from each may travel alongside the passageway as a natural migration route. Natural “buffers” of the Minnesota River prevent excess erosion and sedimentation, for the plants act as natural filters whilst holding the shoreline in place. Flooding of the river can be common, but luckily maps show that even 100 years floods are unable to affect the site due to its higher elevation as a classified “upland system.” However, increased precipitation and water table concerns could result in flooding of the mine. Soil permeability is an important aspect of mine efficiency and safety, and according to one of the GIS maps created, the soil’s drainage class has been labeled “poor.” This quality alone could prolong potential flooding and slow the mining process. On the

positive side however, poor draining soils prevent leachate from entering the bedrock (and potentially groundwater) with ease (South Mine FEIS, 2012).

Soil Seepage

Minnesota considers multiple state and federal regulatory agencies in the regulating, monitoring, and permitting of discharges into groundwater. These agencies include: the Environmental Quality Board, MPCA, MN DNR, MDH, Board of Water and Soil Resources, United States Geological Survey, and USACE.

Despite the rather large outreach the former agencies have in the matter, the state of Minnesota does not have a well-defined standard as to what would be delineated as a “seep.” Therefore, others have researched into the regulations of other state statutes to formulate a better definition of which to adhere. The state of Wisconsin was subsequently considered to have a proper standard of which to follow and therefore this modified EIS will utilize that definition to the best extent. Proper protocol regarding leachate prevention will need to be considered (South Mine FEIS, 2012).

Physical Impacts to Wildlife

According to Section 1, there is only one endangered species known to inhabit the land to be considered for mining. In the nearby marshes, however, there can exist a plethora of species with either obligate (requiring the marsh as habitat for the entirety of its lifespan) or facultative (“vacationing” species) life histories (Mitsch & Gosselink, 2007).

The various sedges, cattails, bulrushes, and arrowheads found in this ecotone are used to a neutral pH of 7. Nearby silica mining could add to plant fecundity stress, which may result in diminished populations and even death if nearby ion release from the processes aforementioned was to change significantly (MN DNR, 2014).

Similarly, if the proposed plan was to be pursued, it would require an analysis of wetland hydrology to further understand how these wetlands receive water, and furthermore how they would survive if a change in volume was to occur. The hydrologic equation for wetland ecology is as follows:

∆v∆ t

=Pn+S i+Gi−ET−So−Go

Where:∆v/∆t = Water storagePn = Net precipitationSi = Surface water in

Gi = Groundwater inET = EvapotranspirationSo = Surface water outGo = Groundwater out

A change in land use on the slope above the wetland may result in a change in hydrology (due to a possible decrease/increase in surface water runoff, depending), this could result in a further change of wetland structure and function, which could alter the plant and wildlife types that utilize the particular niches found within the environment. Since both Type 3 and Type 4 wetlands (and adherent species) are protected under Minnesota State law, it is once again imperative that these ecosystems remain untouched as to prevent desiccation or flooding. For if the plants become more stressed, the animals that use them as food or habitat could possibly leave the area if their habitat was to become scarce or completely altered (Mitsch & Gosselink, 2007).

Physical Effects to the Natural Water Table

Water is always stolen from another location. If excess water is removed from nearby systems, a drop in the water table could alter existing wetland conditions. As well, a cone of depression could occur in a particular area, which could cost hundreds in the digging of deeper wells for nearby residencies (see Figure). More information on wells and their locations can be found in Section 2 (Mitsch & Gosselink, 2007).

Figure 1.6.7. The cone of depression represents a lowered water table due to excess pumping in a particular area. This causes more difficulty regarding water access and therefore costs more money to operate (the well subsequently must be dug deeper in order to operate efficiently).

Water Use Notes

“According to MN Rule 6115.0740, water use conflicts occur where the available supply of waters of the state in a given area is limited to the extent that there are

competing demands among existing and proposed consumptive appropriation users which exceed the reasonably available waters. In referencing the water allocation priorities in MN Statute § 103G.261, the allocation of waters is based on priorities

for the consumptive appropriation and use of water. Consumptive use is defined as water that is withdrawn from its source for immediate further use in the area of the

source and is not directly returned to the source” (South Mine FEIS, 2012).

Minnesota Statute Requirements / Suggestions

Once an option is chosen out of all of the alternatives included within the Modified Environmental Impact Statement, a description could be determined regarding the resulting wetland if known hydrology and geomorphology are combined with the project specifications using the Minnesota Routine Assessment Methodology for

Evaluating Wetland Functions (MnRAM) as a better assessment of cost – benefit analysis.

A MN DNR Individual Public Waters Permit would be required prior to any potential water class impacts (more information can be found in Section 3 on water quality).

A detailed hydrogeologic assessment would need to be performed with input from the Minnesota Department of Health and MN DNR to ensure that the nearby mining will not violate the Wetland Conservation Act’s requirements for shallow and deep water marshes.

Although the existing site for potential mining has been utilized for agricultural processes as of recent, the GIS maps produced for the site show that the underlying water table is quite diverse in depth, ranging from 0 meters from the surface (representative of saturated soils – a requirement for wetland ecosystems) all the way to 110 meters below the surface (see appendix). The flux in water table depth not only could represent possible issues for mining (the area would thereby be easily acceptable to flooding) but could also represent a portion of wetland delineation, which is a process of analysis and mapping as dictated by the United States Army Corps of Engineers and as requested by the MN DNR. Please see the following map to follow for more information:

Figure 1.6.8. The water table depth of the site represents many different annual minimums. This could represent a former hydrologic differentiation of the site before it was plowed and could cause issues if heavy precipitation was to occur.

Impacts to Wetlands must be mitigated under the 1991 Wetland Conservation Act as well as Section 404 of the Clean Water Act. The adjacent wetlands to the site in question will be valued and considered regarding mitigation of significant impacts to water quality, habitat, and overall function. Direct and indirect impacts must be studied and quantified.

If the off – site wetlands were to be harmed where restoration would be necessary, precautions would be taken in order to ensure that as similar conditions as possible are present in the new location. Impacts to wetlands must also comply with the Minnesota Pollution Control Agency’s standards (South Mine FEIS, 2012).

Conclusions

There are many potential environmental effects that could be significant if the proposed project was to be constructed. In order to properly determine the short term and long term effects of the mine, it is imperative that a more extensive study is performed on the hydrology and geomorphology of the surrounding wetlands to further determine their structure and function. Whilst immediate effects may simply reduce plant and animal numbers or biodiversity, long – term effects may change the wetland type altogether, or prevent the site from being considered a wetland at all.

Wetlands are a small, yet important part of the human and natural environment because they:

- Act as sources, sinks, and transformers of biological material- Improve water quality - Stabilize water supplies by protecting shorelines, stream banks, and coastlines- Recharge aquifers- Serve as one of the most diverse habitats for many flora and fauna in the world

It is of the mine’s best interest that little to no harm is done to the soils and water quality that can affect nearby vulnerable ecosystems and the species that live there.