Wednesday, November 30, 2011
How About Horizontal Water Wells?
It's usually called a "radial collector well" in the public water supply world, but it's the same thing. In the water world a caisson, or large water tight concrete vertical tube, is usually constructed from the surface down into the groundwater aquifer and then from 4 to eight radial wells (or more) are drilled out of the base of the caisson. The wells flow into the caisson where a large pump is used withdraw the water. When pumping, the lowered water level in the caisson induces more supply from the radial wells in the aquifer, which is very quickly recharged by the surface water in the river when the well is adjacent to a river, which is most of the time.
One huge difference is that the public supply wells are not fracked. These are typically sand and gravel (alluvial) wells that need no propping or chemical treatments to produce water. How could anyone think of fracking a public water supply well, anyway? But they do tend to produce copious amounts of water. The newest such well in Kansas is for Olathe, KS and has been approved for 7,300 AF per year from a single radial well.
In Kansas there are currently 10 radial collector wells - most of them supplying Kansas City and Overland Park water needs from the Kansas and Missouri River alluviums. I found it interesting that the newest well (Olathe, KS) has been issued two water rights - a groundwater right and a surface water right. Turns out the modeling of this well has concluded that 96% of the total water produced will be coming from surface water recharge while the remaining 4% will be coming from the groundwater aquifer. Novel idea.
I found a 2008 BoR report on the technology that has quite a few facts and figures - although they genericize the process by including angled well drilling and HDD - Horizontal Directionally Drilled Wells. This report was done for the Municipal Water District of Orange County, CA. It states that 220 radial wells were in use the US as of 2002. Most of these are located in relatively larger cities including Mankato, MN; Lincoln and Omaha, NE; Des Moines, IA; Sonoma County, CA and the like, but smaller cities like Pella, IA; Dardanelle, AR; and Bennett, CO also claim usage.
The technology was invented in the 1920's for the oil industry, but the first public water supply use was in 1933 in London, England of all places. The first US application was in 1936. With such enormous amounts of water being produced, I keep wondering when the irrigation industry is going to express their interest. Probably when crop prices rise high enough to cover the significant cost of these hydro-engineering marvels.