I agree the current dig should go ahead and I did a little research.
It's not surprising really that this dig is being done. Indigenous peoples used the Credit River to travel between the lake and areas farther north for thousands of years. This particular site was uncovered in the 1930s (perhaps when the original bridge was built?). Excavations were performed by the Royal Ontario Museum, and as many as 4 bodies were reportedly discovered, along with glass beads, and arrowheads. While the site apparently showed signs of continuous or repeated habitation, most of the artifacts found dated back to the Middle Woodland period (400 B.C. to 600 A.D.) It was named the Hogsback site and given the archeological designation (AjGv-3).
Source:
pg. 45 of the June 2020 environmental report and
pages 17 and 67 of the city of Mississauga's 2022 cultural heritage report.
As there was a known archeological site in the area, an archeological assessment was done as part of the environmental approval process for the new bridge. The archeological assessment led to a dig being conducted on the north side of the highway, east of the river, which took 2 years from 2016 to 2017.
These articles describe the significance of the 2017 dig.
https://www.toronto.com/news/counci...cle_ac9e525f-51f4-5203-92f9-35456ad60efa.html
https://asiheritage.ca/publication/...edit-river-during-the-middle-woodland-period/
Further explorations in 2019 assessed other adjacent areas which might be impacted by bridge construction, but a test pit failed to turn up anything. Also, as part of the bridge construction, part of the riverbed was exposed and excavated in June 2020. Despite the test pit not revealing anything, the environmental approval process mandated a dig be conducted should anything turn up during construction.