Here is a paper that I read some time ago hosted on the USGS website. It should be a start for you.

Also The International Network for Acid Prevention (INAP) guide is very complete as well. 

See section 7 for infos about passive treatment and related references. http://www.gardguide.com/index.php?title=Chapter_7 and http://mine-drainage.usgs.gov/pubs/ICARD_2000_Sibrell.pdf

If you want to repeat what thousands of people did before you, you can conduct another test. The pH will not increase above ca. 7.5 – 8 and it will take about 8 – 14 hours until you get the final pH. Always the same results without statisticaly significant differences. Send my a PM and I will send you about 150 references which you can use to come up with your results. Also look to the "integrated limestone process".

Here I suggest that limestone treatment of AMD could well be standardised, taking profit of other well-accepted methods (BC and ISO on testing, see also GARDguide). However, one of the most important points is water monitoring, upstream and downstream. Not only pH but also conductivity/salinity, suspended matter (or turbidity) and the most critical metals/metalloids.

I have run membrane systems on AMD at pH 1-5 for 30 years. You want to run the membrane at low pH when iron, aluminum and other sparingly soluble metals (pH 7>) are still in solution. The membrane concentrate is then supersaturated and easily precipitates with much less lime than if one simply limed the feed (50 to 90% less lime depending upon the amount of co-precipitation that takes place. Also see http://mdsamericas.com/ for alternatives to Limestone.

Is the purpose of your question to develop some sort of study such as column tests or is it to design and build a real passive system to treat mine drainage?

Thank you guys!