A few weeks ago I was in touch with my friend who is high up in...

A few weeks ago I was in touch with my friend who is high up in the Philippines government and he told me some news that appeared to confirm my apprehensions (in general) about adding cement to tailings. My friend also sent me a large quantity of documents which I have only glanced at.

Anyway backtracking somewhat I went on record two years ago about my apprehensions surrounding cemented tailings and said;

“1. How does one ensure no leakage of cement based tailings into the ground water? 2. Cement also contains heavy metal chromium; hexavalent chromium is toxic to fish and humans.”
See ref; my post 18^th Jan 2014
http://hotcopper.com.au/threads/cdo-update.2167306/page-13?post_id=12823842#.VtVARVR9670

Well to answer my own questions IMO 1. Even with a lined tailings dam there will still be seepage of water from the dam and this water will eventually end up in the ground water and eventually the river; this is un-avoidable. For the second part of the question cement particles which are very fine (likely <5 micron IMO) should not seep from the dam into the ground water unless the cement has not set.

However following the conversation with my friend it raised my curiosity to investigate further; the latest google earth images of the Magpayang River (see below) IMO shows a lightening in the river colour as the river winds past the new tailings dam 5. The change in the lighter colour of the river IMO could be caused by an increase in particulate content by some means; however my observations are purely based on the satellite imagery alone; it is not a scientifically validated statement about the particulate concentration in the river; it is purely a visual observation based on the available satellite imagery.

(Disclaimer; satellite imagery may show colours that do not represent actual topography; please DYOR).

I made some further investigations;
The environmental impact study (EIS) for the mine site is freely available for review (see ref below); in the 2009 EIS document the study of water quality on the surrounding river systems & Lake Mainit was extensively investigated before the mine was designed & built. However the 2009 EIS does not take into account the affects of cemented tailings;

Disclaimer; however there maybe a later version of the EIS which I have yet to discover. From my reading of the 2009 EIS the mine is supposed to operate within strict guidelines of water quality management.

http://contracts.ph-eiti.org/suppor...-2002-XIII, 2002/EIS_Greenstone Resources.pdf

As for question 2 IMO; Well again my comments from two years ago are ringing loudly; in Dec 2015 there was a large kill off of fish in Lake Mainit which is downstream of the mine (see also the 2009 EIS for the mine which studied the affects on fish life in Lake Mainit extensively); the local mayor was none too happy calling for a thorough NGO investigation; see for instance

http://www.mindanews.com/top-storie...uspect-mining-caused-fishkill-in-lake-mainit/

Over the next week or so I will sift through the large quantity of documents my friend sent me and see if I can shed some more light on Lake Mainit and the Magpayang river systems in the current environment.

Ref Google Earth 16^th March 2016; the interpretation of water colour is in my opinion only please DYOR.
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