Ducting suitable to be laid on the ground.

[Triassic]

I’m about to get Fibre Optic cable installed as part of a rural broadband scheme.  
 

I have to lay a duct from the boundary fence to the property, a distance of 180m, with 150m being across loose limestone and outcrop. It’s been suggested I install a small bore duct and thread the fibre optic duct through that, so as to provide some protection.
 

I’m thinking maybe 20mm bore black alkathene! What do you all think? Will this provide the uV and impact protection required? If not, what are the alternatives?

[Temp]

Google suggests the Black MDPE is UV stabilised but not the blue.

 

Its pretty strong stuff but is 20mm big enough? I'm thinking about the diameter of the "knot" connecting draw rope to the Fibre? I've normally used 3/8" rope to pull electrical cable. Double that back on itself and bind with tape. That would be more than 20mm. Perhaps smaller draw rope is ok? 

[Thorfun]

openreach supplied all the ducting for running our new connection to the house. it's the grey stuff they use. have you tried contacting them?

[Triassic]

2 minutes ago, Thorfun said:

openreach supplied all the ducting for running our new connection to the house. it's the grey stuff they use. have you tried contacting them?

Our supplier is Barn not Openreach. To keep costs down they expect you to duct from the boundary to the house.