I sympathize with the reporter, Nir Hasson -- there are so many underground spaces being excavated in the area, it's hard to keep them all straight! He writes: "a metal stonemason's chisel was found in the drainage tunnel last summer". However, the archaeologist, as quoted, did not state that it was found in the drainage channel (sewer). It was found, admittedly nearby, among construction debris at the base of the wall. Here's what's actually going on down there: Near the southwestern corner of the Temple Mount -- years ago now -- the archaeologists DEPARTED from the channel and started driving a separate excavation tunnel along the foundation courses of the Temple Mount itself. Next time the local Muslim authorities complain that Israel is digging next to al-Aqsa Mosque (by which they mean the entire ancient enclosure), please understand that it's not just rhetoric. It's happening.
High school teacher's union threatens strike (Haaretz)
from the article: Archaeologists find 2,000-year old chisel used to build the Western Wall