[Talk-GB] Sewage Outfalls

[James Derrick]

Hi,

On 27/10/2021 09:12, SK53 wrote:
> As sewage outfalls are in the news at present it might be a good 
> opportunity to map some of them, particularly those close to popular 
> bathing beaches.

In case anyone is mapping sea outfalls, you can usefully represent both 
the physical discharge pipe and the "nautical signage" often placed 
around it.

After regulations were tightened to enforce secondary treatment, many 
outfalls were rebuilt with long underwater pipes to discharge treated 
water into the main current of the sea. After many years of sailing 
dinghies in Newbiggin Bay, only disused outfalls are visible even at 
mean low water springs (MLWS on maps - lowest of the low tides). The 
active discharge pipe is buried deep into rock, and then sand. The only 
ground-truth for 1.5km is a yellow buoy to discourage boat anchors.

In case you're not a sailor, OpenSeaMap is a render of OSM that produces 
sea charts and tagging structures such as buoys, markers, and lights 
using international standards for sea marks (road signs for boats!)

https://map.openseamap.org/

My own local outfall marker buoy is therefore tagged using the seamark 
tag which is rendered fully only on OpenSeaMap:

https://www.openstreetmap.org/node/4338899837/

You might also find other 'signs' or 'marks' on the foreshore warning 
boats of the outfall such as fixed poles with shapes on the top - a 
yellow X is one option, but there are a few possibilities. The marks 
should be standard, but as ever there are many standards - offshore IHO 
and inshore CEVNI to name but two.

There are also plug-ins for JOSM to make mapping sea marks easier, and 
add some validation

Happy Mapping,


James

James
-- 
James Derrick
     lists at jamesderrick.org, Cramlington, England
     I wouldn't be a volunteer if you paid me...
     https://www.openstreetmap.org/user/James%20Derrick