Just for info really, but while there are no obvious dirt traps in the wheel arches when I was hosing the rear arches I happened to stick my hand into the hole in the liner around the springs and found a couple of handfuls of mud in behind the liner on both sides that is not easily removed by simply hosing or pressure washing the area. Mine's only been used on muddy wet country roads. MY14 TD4 manual XS Orkney grey.

MY11 TD4 Manual XS Lago Grey, privacy glass, rear spoiler, full ebony leather,rear seat entertainment. Gone
2001/51 plate Disco TD5 GS. Gone
95 N Disco TDi300. Gone

I sepnd about 2 hrs going ovr (well, under really) our freo after any trip to the sand. Yes, sand (and mud I suspect) does get trapped in those places, but it's easy to get a hose (low pressure, high volume) into the access holes in those plastic shrouds to clean it right out. I put the car up on ramps one side at a time to do it. Prepare to get wet

http://www.freel2.com/forum/topic18478.html?highlight=arches At work
At home

"I can't always believe facts I read on the web" - Charles Dickens

winner by default of the tractor vs caravan race