Concern over Land drain ducting

Yellow perforated pipe is fine. 100mm is suitable, and yes the trench should be lined with terram to stop the fines washing from the sub soil, through the gravel and into the perforated pipe causing it to block up after a period of time. If you have any inspection chambers on the run, make sure they are catch pits.

I can only say from the discription that perforated pipe is used as part of of drainage house protection systems. Been yellow is a colour related to gas but this isn't. The perforation in the pipe collects ground water and sends it to a land drain so any kind of textile would defeat its purpose. Its always welcomed customers who are unsure to ask the tradesman questions so misunderstanding don't happen.
Regards
Craig
Make sure pebbles or something similar is covering the pipe before been back filled, v important

If it is perforated, it won’t be very useful for gas :)
Colour is irrelevant.
Depending on agreed specification, geotextile should encase pipe and gravel to stop soil contaminating them.

Hope this helps. Ta. John.

They are typically black, yellow would indicate a trunking for gas. Is more than likely they was out of stock or its what he had left, it still will do the job just may cause some confusion for anyone who is excavating the gsrden in the future

YELLOW COIL LAND DRAINAGE PIPE 50M X 110MM can be used no problem,
Once the trench is completed, it can be lined with the geo-textile. This MUST be a construction grade geo-textile and not a weak landscape fabric which will tear and fall apart when buried, offering no protection whatsoever to the gravel.
..the additional width allows for the wrap-over on top of the gravel backfill.
I hope this answer is good enough.
Marek -Customscape ltd