Thank you for your question regarding ppl underground electrical services and meter base grounding. It is our pleasure to help.
We found the attached document detailing how to install a ppl electric meter. Rule #5 (see page 26) does detail some of the grounding requirements. There may be additional grounding requirements in other parts of the document, as it is quite extensive at 82 pages in length. It may be prudent to review it in some detail to make sure that nothing is missed. But generally speaking, all metallic objects in electrical systems that can be touched by humans, should be bonded to a grounded non-current carrying conductor.
If you have any further questions, please do not hesitate to contact us again.
The Engineering Team at E&S Grounding Solutions
Here is the document we found: