Silica Sand Mining Project Data Gathering

Introduction
The goal of this aspect of the Frac Sand Suitability model for Trempealeau County, Wisconsin was to collect and develop data.  The data includes environmental, transportation and demographic features as well as geocoded locations of frac sand facilities in Wisconsin..  A variety of agencies were used to import this data into a geodatabase in ArcGIS.

Methods

The National Atlas provided a line feature class for railroads in Wisconsin.  Frac sand processes often use railways to transport silica sand from the mine to processing plants and oil wells.  This feature class was downloaded from National Atlas data and imported into the geodatabase.  The United States Geologic Survey (USGS) provides a wealth of geographic data.  For the purposes of this model, elevation and land cover data was acquired from this agency.  USGS provided land cover data from 2006 in raster format.  The MRLC provided a description of the data and a legend for the raster codes.  A National Elevation Dataset was also in raster format.  The DEMs (Digital Elevation Models) had to be shared as two separate tiles because of the large storage capacities of the files.  In ArcGIS, the “Mosaic to New Raster” tool was used to merge the two tiles.  Both sets of data were imported as raster datasets in the geodatabase.

Figure 2-Land Cover Data
(Source: USGS)

Figure 3-Elevation Data
(Source: USGS)

Cropland data was acquired through the United States Department of Agriculture (USDA) Geospatial Data Gateway.  This information will be used to determine land cover in the suitability/risk model.

Figure 1- Cropland Data
(Source: USDA)

The National Resources Conservation Service (NRCS) provided soil data for this model through the Soil Survey Geographic Database (SSURGO).  This data was imported to the geodatabase as a feature class, the component table for soil data also had to be imported.  These features were joined through a simple relationship class using the primary key “MUKEY."

Figure 4- Soil & Railroad Data
(Source: NRCS, National Atlas)

Coordinate systems varied between each dataset.  In order for accurate representation and analysis of the data, a common coordinate system had to be set.  The datum of each dataset was inspected and a coordinate system was chosen based on two factors: common datum and area of interest.  The datum of each dataset was NAD 1983 and the area of interest was Western Wisconsin.  The NAD 1983 UTM Zone 15N coordinate system was chosen because it fit within the datum of all data and it was the best fit for the area of interest.

Geocoding
A spreadsheet from Wisconsinwatch.org (http://www.wisconsinwatch.org/viz/fracmap) was used to create the reference data for geocoding.  The spreadsheet had to be normalized before it could be used in the ESRI ArcGIS geocoder.  To normalize the data, the state, county, community and address had to be separated into individual columns.  Many of the addresses were formatted in PLSS description.  This format is not compatible with the ESRI ArcGIS geocoder.

Figure 5: Normalized Spreadsheet; Source: Wisconsinwatch.org

Once the spreadsheet was normalized, it was uploaded to ArcMap and loaded into the address locater.  The figure below shows the success

Sand Mining Suitability GIS Project Overview

Wisconsin’s rich glacial history has provided abundant sandstone deposits upon its geologic landscape.  This glacial history has created an expansive array of Jordan, Wonewoc and Mt. Simon sandstone formations containing high-quality silica frac sand (Figure 1).  Although sand mining has occurred in the state for hundreds of years, the practice of hydrofracking has rapidly increased the demand for sand mining in recent years.  Hydrofracking pumps a combination of water, frac sand and chemicals under high pressure into underground oil or natural gas wells to open natural fractures.  This allows natural gas or crude oil to be more easily extracted from a well.  It is important to note that no oil or gas wells exist in Wisconsin, but the state’s abundant frac sand resources are sought to meet the demands of the oil industry.

Figure 1: Wisconsin bedrock types; data provided by WDNR

Western Wisconsin has become a hotbed for frac sand mining.  According to the Wisconsin Department of Natural Resources, “Wisconsin has approximately 60 mining operation and 30 processing facilities operating or under construction” and as of January, 2012 “20 new mining operation proposals” (WDNR, Silica Sand Mining in Wisconsin, P. 3).  The extraction of frac sand can potentially cause an array of issues.  Mining may cause dust particles and pollutants to be emitted into the air; the extent of emissions is considered minor, but is a concern for air quality purposes.  Frac sand facilities may be located near rivers or streams; it is possible for run-off from these facilities to reach bodies of water and cause contamination.  Contamination can include increased siltation or erosion. (DNR, P. 24)  Water resource impacts can extend into loss of habitat and ecology, especially in regards to Wisconsin’s fisheries.  Transportation infrastructure can also be impacted by the processes of frac sand mining.  The sand must be transported for the extraction site to the processing site.  The amount of weight asserted onto existing roadways coinciding with increased traffic may cause road deterioration.  These factors can cause a decrease of property values in areas near frac sand facilities.  The potential implications of sand mining, while numerous, are highly contested.

Figure 2: Frac sand processing in Wisconsin
Photo provided by BanksPhotos, iStockphoto

Figure 3: Aerial view of a frac sand mining operation in Wisconsin
Photo provided by BanksPhotos, iStockphoto

The use of a geospatial information system (GIS) can be used to assess these possible implications through a suitability/risk model.  A geospatial information system is used to represent real-world features in a spatial manner.  Spatial information can be used to analyze geographic patterns and determine relationships between features.    A suitability/risk model will use geographic data pertaining to frac sand mining to determine spatial frequencies, analyze network associations and consider the relationships between environmental impacts and frac sand mining.  This model will focus on Western Wisconsin, specifically Trempealeau County.

Sources:

Silica Sand Mining in Wisconsin

Wisconsin Department of Resources, 2012