Where directed, the drain pipe to be laid under Items 3 to 8 shall have a 6-inch T branch. Unused ends of branches shall be closed with a suitable cover well cemented in place. The special of which the 6-inch branch is a part will be measured and paid for as straight pipe under Items 3 to 8; the price bid for each T branch will be in addition to the above payment, and will also include the necessary extra excavation and closing of end if unused.