Frac Sand Mining in Western Wisconsin: Project Overview

Introduction 

Sand mining is not new to Wisconsin, this type of mining has occurred in Wisconsin for over 100 years.  The sand mined in Wisconsin is used in a multitude of way such as, glass manufacturing, foundry molds, and golf course sand traps.  Due to recent surges in hydrofracking the state of Wisconsin has seen an increase in mining permit applications and proposals.

What is Hydrofracking?

Hydrofracking is a technique used by the oil and natural gas companies to extract resources thousands of feet below the earth's surface (Figure 1)  The technique involves using explosives to create cracks in the surrounding rocks.  Following the creation of the cracks, then frac sand, water, and various chemicals are pumped into the well to expand the cracks while also holding them open.  With the rocks cracked and held open it is easier to extract the product which was previously contained by the rock.  Though hydrofracking is not new, advances in the industry have allowed previously non-extractable gas and oil to be extracted.  The same advances have also made the process cost effective.

(Fig. 1)  Illustration of hydrofracking also referred to as hydraulic fracturing. (http://en.skifergas.dk/technical-guide/what-is-hydraulic-fracturing.aspx)

Frac sand is the product which the majority of the new mining companies are extracting.  Frac sand is silica sand, commonly called quartz.  Not all silica sands meet the standards to being used for hydrofracking.  The sand must be almost entirely quartz, very well rounded, uniform grain size, and have high compressive strength (Figure 2).  Large deposits of this type of sand are located in sandstone formations within the state of Wisconsin (Figure 3).

(Fig. 2) Frac Sand with a penny for size correlation. (http://www.disclosurenewsonline.com/wp-content/uploads/2013/07/frac-sand.jpg)

(Fig. 3) Frac sand mines and sandstone formations located in Wisconsin. (http://wcwrpc.org/frac-sand-factsheet.pdf)

Sand Mining Process

Sand mining operations vary from mine to mine.  The following 6 step process illustrates a typical sand mine and sand processing plant.

1. Overburden removal/excavation-- The removal of topsoil and subsoil to expose the underlying sand.  Often the overburden is used on the perimeter of the site to create a berm.
2. Excavation--  Removal of the sand.  Typical mines use large excavating equipment such as excavators or front end loaders for sand removal.  Certain situations require blasting to release the sand from the geological formation.  The excavated materials is then stacked for storage or hauled to the processing plant.  Hauling is done via a semi-truck or trains.
3. Crushing--  The sand deposits which require blasting often require crushing to reduce the size of the particles.
4.  Processing--  The sand must go through additional steps to be used for hydrofracking.  The sand will be washed, dried, sorted, to achieve the desired uniformity.
5.  Transportation-- Through the entire process the sand is transported using a variety of methods.  The preferred method to haul sand is currently the railroad though in some areas dump trucks, gondola compartmentalized trucks, and barges are being used.
Reclamation--  After exhausting the supply of sand from the site the owner/permittee must reclaim the mine area.  There is variation on the requirements for mine reclamation from county to county.  The general rules for reclamation is no steep slopes, no vertical walls though some may be authorized with approval from the county.  After the grading is complete the surface must receive topsoil to allow plants to grow.  Once the topsoil is places, seeding and mulching can occur.

Issues with frac sand mining is Western Wisconsin

The list of issues associated with frac sand mining is quite long as described by the Wisconsin Department of Natural Resources (WIDNR).  I will highlight a few of the issues from the list I feel are important.  If you would like to read more about additional issues please refer to Silica Sand Mining (WIDNR).

During the entire mining process machinery which is burning fossil fuels are being used, thus adding pollutants to the air.  The machinery which is being driven on the public roadway is causing additional degradation to the roadways.  Dust particles are released throughout the entire process.  The sand is often watered in an attempt to reduce the dust.

(Fig. 4) Pin heads displaying air monitoring stations for particulate matter in Wisconsin. For more information see the following link. (http://dnr.wi.gov/topic/Mines/AQSandMap.html)

The processing of the sand requires a large amount of water.  Depending on the plant the average water use is expected to range from 420-2 million gallons per day.  Some processing plants have a closed-loop processing system and others have an open-loop system.  Acrylamide may be present in the wash water from the processing facility.  The US Enviornmental Protection Agency (EPA) set the the maximum allowable level of acrylamides at 0 in public drinking water.  This equates to the possibility of contaminating the ground water with the wash water from the processing facilities.

Class Overview

Frac sand mining is very controversial especially since the great increase in the number of mines across the state.  Many people rejoice with all of the job opportunities which become available when a new mine is created in their area.  The environmental effects, landscape changes, and risk for water, or air contamination are argued from the opposing side.

The main focus for our GIS II class will be the suitability and risk of mining within Trempeleau County and several other counties in Western Wisconsin. Our class will be downloading data from multiple federal and state agencies for analysis from which our suitability and risking modeling with be derived.  The progression of this work will be displayed in later blogs.

Sources

Industrial Sand Mining (n.d.). In Wisconsin Department of Natural Resources. Retrieved October 7,  2015, from http://dnr.wi.gov/topic/Mines/Sand.html