The County Council carry out monitoring visits for all mineral and landfill sites to ensure compliance with the terms of their planning permissions.
DCC's site monitoring reports can be found here.
Aggregate Industries' Blackhill, Venn Ottery and Hillhead quarries were all inspected by DCC in 2016. See which planning conditions AI has complied with, and which it hasn’t:
Blackhill Quarry monitoring report p.14-15
Venn Ottery Quarry monitoring report p.26
Hillhead Quarry monitoring report p.31