Sulfur scrubbing works by supplying a slurry of calcium carbonate and reacting it with the H2S emissions resulting in the formation of gypsum. The cost of a scrubber is really relative to the goal. Let's say that you establish a maximum H2S limit on emissions as 5 PPM, the time for reaction is completely dependent. It's probably 90% cheaper to raise the limit to 10 PPM.

There has been no groundwater contamination from hydraulic fracturing.

Well I went to college and graduated in 2008. First year out of university I was making over $100,000 [BS Chemical Engineering]. Seems like a good deal to me.