Above Ground Recycled Water Systems

Our HOA in Carlsbad, Ca is trying to determine how and when to replace a cast iron irrigation system in our HOA. The current system is over 30 years old and is starting to break down. We don't want to replace this system yet but want to consider options so we can present them to our general HOA. My concern is the use of above ground purple pipe as a replacement system. The city's specification calls for trenching and burial but this is costly and if above ground systems can be used, I think it would be to our benefit. We would have to anchor the pipe so as to minimize damage and bury it near high traffic areas but I don't know of any HOAs that have done this or if it is possible. Can anyone give me their thoughts so I can research if it could be applied to our situation? Thank you