Neville Rockhouse never stops thinking about it, but on Thursday he will think about it more than most days.
The fifth anniversary of the Pike River mine disaster will be marked on   November 19, and few people's lives have been more affected by the incident than that of Mr Rockhouse, who was the safety manager at the New Zealand mine but also the father of one of the 29 people killed.
In the years since the disaster, Mr Rockhouse has emerged as a campaigner for safety and corporate responsibility.
"Someone famous said if we don't learn from our past mistakes we are destined to repeat them, and in the mining industry in particular, it may take 20 years, but we repeat the same things over and over again. The same sort of shit, different day," he said this week. 
The folks at BHP will know what he means. Close to 30 years since BHP's mine wastes, or "tailings" as they are known, polluted the Ok Tedi river in Papua New Guinea, the company's top brass were en route to Brazil this week to assess the damage from a tailings dam failure at the Samarco iron business BHP shares with Brazilian miner Vale.
Dying forest on the Ok Tedi River site of BHP's worst previous accident. Photo: Alex De La Rue
 It was just before dusk Brazilian time on Thursday,   November 5, when this low-profile part of BHP's global empire found itself amid a disastrous calamity that would capture the world's attention.
Samarco's mines and dams are in the warm, lush hills of Brazil's "iron quadrangle". An area so steeped in mining history they named the local state Minas Gerais, which roughly translates to "General Mines".
For reasons that remain unclear, yet hotly debated, one of the three dams used by Samarco for storing wastes or tailings collapsed.
The three dams were designed to work in a tiered, co-ordinated way, and so when the water and banks of the highest-positioned Fundao dam began to slide, they pushed straight into the Santarem dam, which was also seriously affected.
With Samarco being pushed to raise production in recent years, the waste levels in the dams were high, to the extent that British company Dyrhoff had recently been hired to raise the height of the Santarem dam with an extra metre or so of rubber girding.
The failure of the two dams created an enormous, fast-flowing torrent of mud, water and rocks that flowed down the hill before smashing and smothering Bento Rodrigues; the small, nearby village created mainly to house Samarco workers.
Houses were destroyed or left with vehicles pushed onto their roofs,  amid a scene of chaos and destruction. With nightfall imminent, rescue efforts and communication flows were hampered.    
Uncertainty over the precise human impact of the disaster remains to this day. BHP issued a statement on Friday confirming nine people were dead and 19 were still missing. Hundreds have lost their homes, and about 500 had been relocated temporarily.
One of those confirmed dead was a five-year-old girl named Emanuely Fernandes, whose aunt spoke to reporters after her funeral on Thursday morning.
"This is a nightmare. I never thought we would have to live through anything like this ... We are homeless and my five-year-old daughter was a great friend of hers and she was always playing in my house," she said.
Then BP chief executive Tony Hayward faced criticism over his response to the Deepwater Horizon disaster. Photo: Sean Gardner 

Disaster brings scrutiny
The way large corporations respond in such moments of tragedy and disaster is always scrutinised closely.
As former BP chief executive Tony Hayward discovered in the aftermath of the 2010 Deepwater Horizon oil spill in the Gulf of Mexico, it's very easy to disappoint a public whose anger and sadness are still raw.
BHP's response to the Samarco news was in stark contrast to Hayward in 2010 who was criticised for downplaying the impact of the Gulf of Mexico spill and for failing to take responsibility.
Details were still sketchy when BHP's chief executive Andrew Mackenzie fronted the press for the first time on   November 6 in the bowels of BHP's Melbourne headquarters.
A clearly solemn Mackenzie spoke of "very tragic circumstances" and warned that Bento Rodrigues had been "devastated". He vowed the company would provide its full and complete assistance but could say little else, including on what had transpired with the dams.
"It is extremely important to me and everybody who works for BHP Billiton, and I believe our shareholders, that today we offer our deepest sympathies to the people of Minas Gerais," he said.
Mackenzie and his iron ore president Jimmy Wilson were en route to Brazil to tour the affected areas before the weekend was out, and on Sunday the BHP board published its own statement.
Few in the communications industry have found fault with BHP's approach but the same cannot be said for Vale, which came under fire for publishing nothing but a five-sentence statement in the first four days of the disaster.
It was later revealed that Vale chief executive Murilo Ferreira had made an unpublicised visit to the affected site within 48 hours of the disaster, but by Wednesday the negative perception of Vale's behaviour was further entrenched when a company spokeswoman engaged in clumsy email exchange with the Wall Street Journal.
"Vale is only a mere shareholder in Samarco, without any operational interference in the management of this company, whether directly or indirectly, closely or remotely", said the Vale spokeswoman in an email, despite the presence of Vale representatives on the Samarco board.
"Vale really doesn't have any responsibility for the unfortunate and sad accident that occurred in Mariana."
Mackenzie and Ferreira then fronted a press conference to repeat their commitments to look after the local community and unveiling a compensation likely to stretch to $100 million.
President Dilma Rousseff, accompanied by Minas Gerais state Governor Fernando Pimentel, looks out over the dam site. Photo: Brazil Presidential Press Office via AP

Brazil president vows to pursue miners
It hasn't impressed Brazilian authorities.
President Dilma Rousseff on Thursday announced preliminary fines of 250 million reais ($93.2 million) against Samarco after flying over the affected area, and federal prosecutors announced plans to work with state prosecutors to investigate possible crimes that could have contributed to the disaster at the mine.
???"We are determined to hold responsible those who are responsible for this," Rousseff told reporters, citing the two multinationals by name.
Rousseff, a native of Minas Gerais, also spoke with the chief executives of BHP and Vale, telling them the Brazilian government expected them to pay for rescue and clean-up efforts, as well compensation for more than 500 people who were displaced because their homes had been destroyed.
A top federal prosecutor meanwhile says the federal government will form a taskforce with Minas Gerais prosecutors to see if federal crimes have been committed.
"Vale and BHP were completely careless in terms of prevention," says Sandra Cureau, an assistant prosecutor general in Brasilia, Brazil's capital. "There has been a total lack of concern with the victims."
Contaminated waste from so-called tailing ponds is flowing through two states, interrupting the water supply of hundreds of thousands of people and raising questions about the potential impact of the waste on residents' health, agriculture and the ecology of the region.
There could be more to come too. BHP and Vale are working still to secure a third dam.

Transparency is crucial
Neville Tiffen is the former global head of compliance for Rio Tinto, and says while it is difficult to comment on a situation that is likely to attract legal scrutiny, transparency and communication remain crucial.

 "I'm sure BHP and Vale's own lawyers and the lawyers for the insurance companies will be watching every word they are saying," he said.

 "This is where a lot of companies have failed over the years when they respond to major crises or even minor crises. The tendency from a lot of people is to put up the shutters and not communicate well."
Critiques of style and symbolism were soon replaced by matters of more substance.
A 2013 report warning of possible design flaws in the Samarco dams emerged, raising speculation that the accident could have been avoided.
Written by a geotechnical institute linked to the University of Minas Gerais, the report warned that waste piles had been placed too close to the tailings dam and were a threat to the stability of the dam.
The report also called for contingency plans to be drawn up given the potential for harm to the towns in the valley below if the dams failed.
The report suggested any reissuing of the dam licence should be conditional on that contingency plan being completed, but Samarco was reissued its licence in 2013 without filing the contingency plan. 
"What happened was a mistake in the operation and negligence in the monitoring," declared Carlos Eduardo Pinto, the state environmental prosecutor for Minas Gerais, citing the report as evidence.
BHP on Friday discounted that theory as being behind this disaster.
"BHP Billiton notes that the lnstituto Pristino report, that has been the subject of recent media commentary, refers to a  potential future risk relating to the interaction between Vale's waste rock pile and the Fund&atilde;o tailings dam," a company statement says.
"We understand from Vale, that the inspections undertaken by them, and photographic evidence, indicate that this waste rock pile is intact and has not failed into the Fund&atilde;o Dam."

Stock plunging
While BHP's leadership fights to retain the trust of the local communities in Brazil, the financial community back in Australia seems to be losing some faith in the BHP story.
The stock hit 10-year lows this week and, unlike recent share-price slumps, investors appear to have little interest in seizing on the low prices driving its value below $20 on Friday.
Citi analyst Clarke Wilkins estimates that BHP's 50 per cent stake in Samarco accounts for less than 1 per cent of the miner's net present value, so its suspension should not alone have triggered the rout in BHP shares seen this week.
But Mr Wilkins notes the cost of rehabilitation, rectification and compensation in Minas Gerais remains "highly uncertain", and that may be concerning some in the market, aside from the concerns about weak commodity prices.
Mr Wilkins has assumed it will cost the Samarco partners at least $US1.1 billion to clean up and compensate the local communities.
Most analysts are now modelling for BHP to be without iron ore from Samarco for three  to five years, and Mr Wilkins believes there is only a 50 per cent chance of the mine being reopened
"One week on from the catastrophic and tragic failure of the Samarco tailings dam, we are still left with more questions than answers," he said in a note to clients.
Despite all its talk about safety, the unfortunate truth for the mining industry is that tailings dam failures like the one that rocked Samarco are not rare.

Dam collapses too common
Tailings dam expert Dr Gordon McPhail, of SLR Consulting, says failures occur disturbingly often.
"Tailings dam failures on the scale of the one you are speaking of occur at least once every two years somewhere in the world," he says.
In 2014, it was Imperial Minerals under fire for allowing a tailings dam spill at Mt Polley in Canada. In 2013, Sherritt International was under fire for allowing coal wastewater to flow into tributaries of the Athabasca River.
In 1997, BHP had another tailings dam problem at Pinto River in the United States.
Brazilian prosecutors continue to investigate whether crimes were committed in the construction and management of the Samarco dams, and the government is considering fining the two multinational miners involved.
Despite the regular safety incidents, occasional fatalities and apparent failure to learn from mistakes, Neville Rockhouse has not given up on the industry altogether.
"I am still pro-mining, but I think it is critical to be acutely aware of your heritage and your past and there is stuff you just can't shortcut," he says.
"When we start mucking around with the basic rules and the basic principles of the mining industry, that is when we allow the possibility for shortcuts and wrong interpretations to flow into the equation, and that often leads to a disaster."