In “The Phantom of The Opera” The Phantom has a lair in the sewers beneath The Palais Garnier Opera House in Paris; it’s not quite like that in Chalkwell.
At the west end of Chalkwell Esplanade there is a drain cover, and you can, after rain or during showers, hear a great whooshing and roaring of water, presumably surface water heading to the nearby outfall jetty. This is the first part of the recording from July and however great the flow, it ends quite rapidly, which is what you hear here.
There also seems to be some kind of float or valve, you can hear this banging about at all sorts of times. This is the second part, trying to record the Celestine rumbling out to Vlissingen I then heard this banging starting up so was able to walk over to record it. There seems to be some kind of whooshing noise going on as well; I’ve no idea what.
The first part is from about 9.30pm on 23 July 2017, the second 11.50pm on 10 January 2018.