Questions concerning the A9 Kincraig to Dalraddy dual carriageway: EIR release

I would like to request the following information with regards to the A9 Kincraig to Dalraddy upgrade:

1. Was the ditching, in which heavy duty plastics are used as a material, included as part of the construction contract and specified as built?
2. Was the use of heavy duty plastics for ditching signed off by Transport Scotland?
3. How much heavy duty plastics were used as part of the ditching works (miles and width)?
4. What is the total distance of ditching along this section which use heavy duty plastics?
5. What is the expected lifetime of the heavy duty plastics?