Generically, Alkathene appears to be low-density polyethylene tubing. [In the US, polypropylene in coils is a common material for water lines.] Polyethylene is quite resistant to a lot of organic-chemical reactivity. Other than satisfying Code requirements, I don’t think it would be a big issue for use with PVC-jacketed cable. It may be wise not to reduce the buried-raceway depth from that mandated for directly-buried cable. If splices and terminations for Alkathene are of smaller than that of the tubing itself, fill calculations should be based on the fitting inside diameter.
http://www.southwire.com/wc/catalog/sec19/19-1.pdf and similar to 1999 NEC Article 343 — Nonmetallic Underground Conduit with Conductors
