In Situ Leach Mining is pretty nasty and there are a couple of points worth considering about it.
First, it is restricted to soft ores. The *availability* of this method is not indicative of total supply. Uranium in hard ores still have to be refined with crushers before processing further.
Acid leech mining is 'in-situ' - meaning the acid is pumped into the ground to dissolve rock. The risk you introduce with this method is polluting the water table. Any failure to assess the geology properly and it poisons aquifers. Some of these are used for farming so water is a pretty important commodity especially in dry continents where they mine uranium. I beleive this type of mining is illegal in the US for similar reasons.
It's a similar externality to the coal industry releasing radionuclides in ash into the air, except into water table instead, as in both cases we are talking about a natural radio-isotope, i.e. before enrichment. So it may not be a worthwhile risk to take to get uranium that way.
The liquid tailings produced have to be contained in acid dams. This liquid has a chemical and radiological toxicity of it's own and we have to store this by-product.
Uranium mining already produces liquid acid effluents and I recall that one of these sites had a 2 megalitre acid tank, full of radioactive effluents, burst in a world heratige national park a few years ago.
It may not be wise to trust water tables to these guys based on their existing record considering that ISL will create a lot more liquid tailings than the existing processes.
However it neatly illustrates the core design issue of the once through cycle used in modern reactors. The front end industrial processes (mining) forces you to make this essential choice:
1. you crush and process the ore and use a huge about of energy to get your fuel
2. You spend less energy but take a really big risk
These are the options the Nuclear industry has to consider to get it's fuel, it's no better than coal this way, just differently bad.
Of course the third risk is if you run out of that available fuel you *have* to use hard ores which means you have committed yourself to a very low energy return for the remaining lifetime of your new AP1000 or EPR.
This might also provide enough context to understand how the thorium fuel cycle creates a second similar problem with a different waste stream and, why the development of burner reactors was so important to end mining whilst transmuting existing transuranic stocks from the once through cycle.
Mining and refining nuclear fuel is almost a footnote
I think you will find that the energy consumption of this front end industrial process is the whole reason to consider ISL and that both of the mining processes create significant negative environmental externalities.