July 7, 2025 Construction Update

SumCo has completed the demolition of the river left (i.e, east) dam abutment and the construction of Phase A water controls, including installation of dewatering sumps just upstream of the dam and construction of a temporary by-pass channel. Daily air quality monitoring is ongoing, and to date there have been no exceedances documented. There has been some visible dust from gravel delivery, however, a water truck has been brought on site to mitigate dust. In addition, SumCo plans to spread calcium chloride on the staging area located downstream of the dam as needed in order to further control dust. The first weekly air quality report can be found here.  Going forward, it is anticipated that weekly air quality reports will be posted on Wednesday or Thursday of each week.

Archaeological monitors were on-site to observe construction on June 26 and 30 and July 1 – 3. Thus far, construction has occurred in low archeological sensitivity areas; historic glass pieces have been identified but nothing has been found which would require additional archaeological documentation or investigation. 

For the week of July 7 – July 11, the impoundment will lower due to the Phase A water controls installed the previous week. Excavation in the northern area of the impoundment is expected to begin mid-week. Sediment will be stockpiled on-site as needed, pending transportation to an out-of-state receiving facility. In addition, traffic control signage is planned to be installed mid- week on Wahconah Street, and Rectangular Rapid Flashing Beacons (RRFB) are planned to be installed at the existing crosswalk on Wahconah Street near the intersection with Mohawk Street.