WATER RESOURCE IMPACTS ASSOCIATED WITH THE SAND-MINING BOOM IN WESTERN WISCONSIN: A COMPARISON BETWEEN AGRICULTURAL ACTIVITIES AND SAND PROCESSING
The rapid increase in sand mining has led to concerns about truck traffic, reclamation, generation of respirable dust, and water resources. Water quantity and quality issues rarely are compared to familiar agricultural activities.
Dairy cattle drink between 20 and 50 gallons of water per day. A 1000-head industrial dairy operation requires 20,000 to 50,000 gal/day for drinking water alone. A center-pivot irrigation system can pump 1000 gal/minute from the ground. An irrigation system watering a corn field for 24 hours extracts 1.4 million gallons of water.
Industrial sand must be washed before it is shipped to users. EOG runs ~2 million gal/day through its sand plant in Chippewa Falls, WI. Most of this water is recycled, so the plant requires ~18,000 gal/day of “make-up water.”
Flocculants quickly remove clay particles from the water, permit effective water recycling, and greatly reduce the water demands for sand processing. Polyacrylamide, the most common flocculant, is safe and used in most municipal wastewater treatment facilities. However, polyacrylamide commonly has trace amounts of acrylamide -- a neurotoxin. If acrylamide gets into the ground water, is it likely to cause health problems?
Acrylamide degrades to carbon dioxide and ammonia rather quickly in the environment (US EPA, 1985). In oxygen-rich soils, 74-94% of the acrylamide breaks down within 14 days. In oxygen-poor soils, 64-89% of the acrylamide breaks down in 14 days. In river water, 10-20 ppm levels of acrylamide degrade completely in 12 days. Because horizontal ground-water flow velocities are typically on the order of centimeters/day, acrylamide will not persist long within the ground water. This reduces, but does not eliminate, the chances for adverse health impacts. Other activities such as applications of manure, nitrate fertilizers, and pesticides also must be monitored carefully to protect water resources.