Factors including depth to workings, mine water status and occurrence of multiple seams were included and a detailed description of the method can be found in the main body of this report.
Cafodd ffactorau sy’n cynnwys dyfnder i’r gwaith, statws dŵr y mwyngloddiau a gwythiennau amryfal eu cynnwys a cheir disgrifiad manwl o’r dull ym mhrif gorff yr adroddiad hwn.