Noida, Aug 11 (PTI) The Supreme Court-appointed technical expert on Thursday gave its approval for rigging of Supertech"s twin towers with explosives, according to officials.The nod of the Central Building Research Institute (CBRI) was the last approval needed for the charging -- rigging of explosives inside the structures -- of the twin towers located in Sector 93B here, they said.The nearly 100-metre tall illegal structures are so far scheduled for demolition at 2.30 pm on August 21, they said.However, it appears that the demolition date would be deferred since the charging process would take around a fortnight."The CBRI has given its approval to demolition firm Edifice Engineering to proceed with the charging process," a Noida Authority official said, requesting anonymity."The CBRI was satisfied with the responses related to safety measures after Edifice and Supertech agreed to have the structural audit of nearby buildings done before demolition of the twin towers," said the official.Supertech and Edifice, the official said, have assured the CBRI of putting all safety and risk mitigation measures in place in the Emerald Court and ATS Village societies, adjoining the twin towers.The Supreme Court is scheduled to take up hearing in the twin tower demolition case on Friday after which the charging process is likely to begin, according to the official.More than 3,500 kg of explosive will be filled in around 9,400 holes drilled in the columns and shears of the skeletal structures of the twin towers, according to officials.Supertech"s Apex and Ceyane towers in Noida Sector 93A are scheduled for demolition in pursuance of a Supreme Court order last August which noted that the structures had come up in violation of building norms. PTI KIS RHL