More data has emerged on many fronts. One, the extent of damage to water supplies has become clearer, and also the threat of associated damage like earthquakes. Protesters in Youngstown Ohio recently chained themselves to fences to try and stop more wastewater injection into wells there, because on New Years Eve it triggered a whole swarm of earthquakes.
The paragraph above is extracted from the website below: https://www.chinadialogue.net/article/show/single/en/5062-Bill-McKibben-China-should-rethink-gas-fracking
According to the Oxford Dictionaries online, the word "fence" refers to "A barrier, railing, or other upright structure, typically of wood or wire, enclosing an area of ground to prevent or control access or escape." (http://www.oxforddictionaries.com/definition/english/fence) Nonetheless, it remains confusing for me to understand.
Does it mean the "fences surrounding the wells there" or "lines formed by protesters as they chained themselves one another and thus looked like fences"?
Could someone please tell me? Thanks a lot.