All aspects of mine tailings facilities are now under intense scrutiny

The global reaction to the Brumadinho tailings dam disaster in January 2019 has brought all aspects of mine tailings facilities under intense scrutiny. This is especially true for tailing dam volume measurements and the histories of dam construction and tailings deposition.

The thickness and volume of tailings in the Mufulira tailings dam, Zambia, as measured by March 23, 2020 WorldView satellite stereo photos and September 22, 1967 declassified US Keyhole spy satellite stereo photos.

 

Independent measurements of the current volume of tailings and water in the world’s tailings dams

There are no accurate volume measurements of many of the world’s tailings dams.  PhotoSat has applied new technology to 50-year-old declassified US spy satellite data to be able to accurately measure the volume of tailings deposited in the world’s tailings dams since the mid 1960’s.  Using modern stereo WorldView satellite photos, PhotoSat surveys the current topographic surfaces of tailings dams to accuracies of better than 20 cm in elevation.  Surveys of the mid 1960’s topographic surfaces using the declassified spy satellite data enables the accurate measurement of the volumes of tailings

A cross section of the Mufulira tailings dam showing the probable distribution of tailings pond sediments as determined by the processing and interpretation of 315 satellite photos taken between September 1967 and March 2020.

 

The need for independent, verifiable, tailings dam histories

For many of the world’s tailings dams there is no survey data showing much of their construction and depositional history. PhotoSat provided satellite data to assist with the creation of tailings dam histories for several recent dam failure investigations. Through our participation in these projects we recognized the need for independent, verifiable, histories of the construction, maintenance, and depositional history of mine tailings dams.  

 

PhotoSat pioneering the use of 1960’s declassified US Cold War spy satellite photos for tailings dam histories and volumes

PhotoSat has applied modern data processing techniques, including Deep Learning photo matching processes, to extract the topographic elevation data in declassified US Keyhole spy satellite photos taken in the 1960’s.  These photos were declassified by US President Bill Clinton in 1995.  The Keyhole satellite photos were used by the US to monitor Soviet nuclear bomber fleets, intercontinental ballistic missile launch sites and nuclear test sites during the Cold War. 

The 1960’s Keyhole satellite photos have ground resolution of approximately 1.5 m.  The first time that satellite photos with better ground resolution then the Keyhole photo was over 30 years later, with the availability of 1m ground resolution IKONOS satellite photos in 2000. 

To our knowledge, PhotoSat’s use of 1960’s stereo Keyhole satellite photos to measure the volume of tailings in the Mufulira tailings dam may be the first modern use of elevation survey data extracted from 1960’s era stereo Keyhole satellite photos to solve a practical engineering problem.

A picture containing text, book, photo, sitting

Description automatically generated

Keyhole, KH-4 reconnaissance satellite photograph of Dolan Airfield, USSR (now Kazakhstan) taken c.1968. Visible in the photograph are two squadrons of Tupolev Tu-16 "Badger" bombers. The inset shows a 70 mm mylar film strip from the KH-4 satellite camera. The KH-4 cameras took up to 10,000 meters of film which was deorbited in special canisters. The cannisters descended by parachute and were recovered in mid air by specially equipped aircraft. Poster made for a 1995 National Reconnaissance Office (NRO) conference or press event. (National Air and Space Museum Archives)

Investors and insurers want information on tailings dams

Investors and insurers are looking for independent sources of information on tailings dam safety.  Mine owners should benefit by being able to provide their potential investors and insurers with independent, verifiable, studies on the construction and depositional history of their tailings dams.