LPG separation distances

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We have been informed that our neighbours LPG Bulk gas tank does not comply to the separation distances and siting regulations in several ways. That are set out on both Calorgas and Shell websites. Are these separation distances and siting regulations enforceable by law?
Two examples of noncompliance are :- The tank is situateds less than a meter from the boundary, and not the three meters required. The tank is completely hidden under trees and enclosed with bushes. According to both websites there should not be a tree or shrub within 3 meters. There are other noncompliances.