concealed conduit meaning in Chinese

暗管
暗线导管

Works on the building of the concealed conduit started on 28th august
64亿元免息贷款，兴建密封式供水管道。
In order to prevent dongjiang water being contaminated on the way to hong kong , the guangdong authorities proposed the construction of a 83 - km concealed conduit from qiaotou town of dongguang to the shenzhen reservoir . the estimate cost would be as high as 4 . 7 billion rmb
广东省政府建议兴建自东莞桥头镇直达深圳水库、全长83公里的封闭管道，避免东江水在运港途中受到污染，预计工程费用高达47亿人民币。