Under Arbed 3 and Nest 2, revised arrangements to quality assure the work undertaken were put into place to reduce the risk of problems arising in the future.
O dan Arbed 3 a Nyth 2, mae trefniadau diwygiedig i sicrhau ansawdd y gwaith a wneir wedi cael eu rhoi ar waith er mwyn lleihau'r risg y bydd problemau'n codi yn y dyfodol.