Eden Prairie’s water supply originates deep underground in the Jordan-Prairie du Chien aquifer group, which also provides drinking water to most of the metropolitan area cities.
An aquifer is a soil, gravel or rock formation that contains and allows the movement of water. Rock, which seemingly is solid, can actually have very small voids, or pore spaces that can hold a significant amount of water.
The Jordan Aquifer is vast and extensive in area, covering hundreds of square miles.
Eden Prairie’s 15 wells are drilled to an average depth of 398 feet, and the pumps are located about 200 feet down into the wells. Water is heavy, so it requires much energy to lift the water from the pump to the surface. Imagine an average round mop bucket. The bucket contains about 2 1/2 gallons of water and weighs 21 pounds when full. Each foot of depth in an Eden Prairie well contains about one mop bucket of water weighing 21 pounds. Moving water from a depth of 200 feet is like lifting 200 mop buckets of water weighing 4,200 pounds. Every second the well is running, it is lifting 4,200 pounds. Just imagine the energy it takes to do this work!
Water withdrawn from the ground is replenished by water moving in to take its place. Eden Prairie’s wells are constructed in sandstone, a material which is very much like a brick or landscaping stone. Water moves very slowly through this material, at a rate of less than 2 feet per minute, so it takes considerable time for water to migrate from other locations to our wells.
Rainfall percolates ever-so-slowly through the soil moving downward until it eventually reaches the water table. Some places, such as the area around Eden Prairie, have layers of impermeable stone or clay between the surface and the aquifer, called “confining layers.” These clay or stone layers do not have pore spaces and thus prevent water from moving downward, and in a sense, “confine” the water below from surface water influence. Displaced water must then be replaced by water coming from a horizontal direction. At the rate water moves through stone, it can take many, many years for water to be replenished from the surface. Some deep well water commonly found in the Midwest can be tens of thousands of years old.
Impermeable confining layers above the Jordan Aquifer in Eden Prairie serve to isolate the water supply below from contaminants introduced into the environment above the surface. These confining layers are not totally continuous, but they do provide an added measure of protection for our water supply.
Eden Prairie’s wells are very large, producing an average flow of about 1,300 gallons of water each minute of operation. When all of Eden Prairie’s wells are pumped at the same time, 26-million gallons of water can be delivered during one day. One well produces almost 2-million gallons in one day.
Peak daily water consumption in Eden Prairie has been as much as 22-million gallons of water on the hottest, driest days of summer over the last decade. Winter water consumption, when irrigation is not in use, is almost 6-million gallons per day. The average per-capita consumption of water among residential water customers in Eden Prairie is 74 gallons per person, per day.
Eden Prairie has more than 326 miles of large, underground water mains to deliver water to each home and business. Our largest underground water main is 36 inches in diameter.
Eden Prairie’s water treatment process softens City tap water to 5 grains of hardness, eliminating the need for residential water softeners.