Assuming the dry hydrant has been installed to meet the requirements of OBC 3.2.5, the only provision I can see is:
18.104.22.168. Private and public water supplies for fire protection installations shall be maintained to provide the required flow under fire conditions.
It doesn’t give much to go on. Given the lack of direction, it would be interesting to see the outcome if an order was issued to comply with the form and requirements in NFPA 1142 was appealed.
Perhaps a change that should be requested to the fire code to provide requirements pertaining to the maintenance of dry hydrants.