Hidden Depths

Dorothea Quarry, Nantlle, North Wales: disused since 1969, it has over the years found favour with divers, due its depth and the interesting topography beneath its surface. In recent years it has been run by North Wales Technical Divers, a branch of the British Sub-Aqua Club, under license from the landowner. These days, admission is restricted to divers qualified to carry out mixed-gas decompression dives [source: Divernet]. There was a spate of fatalities there in the eighties and nineties, and diving was 'banned' to little or no effect due to the popularity of the place in the diving fraternity. Divernet this week reported yet another fatality: a 60-year-old diver was killed on 31st May, with North Wales Police stating that the death is not being treated as suspicious.

On reading this piece quoted in a local online news outlet, I Googled the Nantlle quarries and came up with some interesting stuff that could possibly be relevant. First off the bat was an article from The Daily Post of 18th April, 2013, about a smaller disused quarry on higher ground above the Dorothea: Twll Balast, which was used as a tip by the local council and by a plastics company operating in the area in the sixties, as a place to dump industrial waste chemicals. This much came out of a report mentioned in the Post article, commissioned by Arfon Borough Council in 1992. Much was made of the long-term toxicity of the waste submerged in the pool formed by the flooded quarry, and of the worry that the contents of it could leach into the nearby Afon [river] Llyfni, which feeds the town of Penygroes.

The Post article, written thirty years after the Arfon report, which was categoric in its assessment of the severity of the issue, and which rendered any potential sale of the site void due to the crippling costs of a clean up, makes rather light of the situation in hindsight. It is also a poorly sub'ed article in that it is internally self-contradictory. It's header reads 'Twll Balast "not thought to be" contaminated'. Its sub-heading contends that 'A QUARRY [sic], which had been subjected to years worth of industrial dumping, is NOT [sic] contaminated.' At the time of the article's publication, a further survey had been commissioned by the site's owners, a 'consortium of businessmen' incorporated as Penygroes Holdings, who had bought the site with a view to creating a leisure resort with hotel, diving facilities and outdoor pursuits centre.

The survey, by Environ UK Ltd. [carried out for the princely sum of £10,000, would you believe]  -  identified the site to be of little risk to the local environment and water-courses, excepting the possibility of agitation to the sediment at the bottom of the lake, which could be caused by rockfall [not infrequent in the old quarries] or geological activity [minor earthquakes are quite common round here], which in their opinion could cause leaching of the chemical components of the sediment into the watercourse and thence into all points below the quarry. This much was recognised in the later report, resting much on the relative immobility of the contaminants. However, at no point did they state categorically that the place was uncontaminated, and indeed, what depth of survey could be bought for ten grand in the 2010's?

Which brings me to the question of Dorothea, the much larger, main quarry of the group at Nantlle, which lies below the smaller quarries, including Balast, and which must take water from those higher above. The worry was always that any pollution in the upper quarries would find its way into Afon Llyfni, but no one was particularly interested in the rest of the quarry site, seeing only the possible effects on the populated area of Penygroes itself. The original report was quite clear in its findings and the list of chemicals, including metals such as lead and cadmium, industrial solvents and other rather unpleasant substances, were present in significant enough quantities to make the site commercially unviable. Given the geology and topography of the place, shouldn't someone be looking into connections between Twll Balast and the glut of fatalities in Dorothea? Given the nature of some of the pollutants mentioned in the report, if Dorothea itself is contaminated, might there not be some connection? Speculation, maybe, but I would have thought it worth consideration...