Location
Grand Rapids, Michigan
Start Date
15-5-2024 10:30 AM
End Date
15-5-2024 11:00 AM
Description
Dewatering System Installation Methods for Ash Dewatering and Deep Depressurization- A Case Study Authors Mr. Christopher Gee - United States - Dominion Dr. Paul Schmall - United States - Keller Mr. Shawn Coughlin - United States - Keller Mr. Christopher Jones - United States - Haley & Aldrich Inc. Abstract Hydrogeologic conditions of this project require a multi-faceted approach to facilitate not only CCR dewatering but also deep depressurization of underlying highly permeable soils. Previous construction experienced significant and sustained groundwater inflows from beneath the ponded ash because the pond was built over the pre-existing river bed in braided stream channel geology. This previously capped pond will now be closed by removal, requiring access for dewatering installation on top of a previously installed surface liner which will be maintained to prevent precipitation and surface water infiltration over the duration of the project. Unique to this project, wells were installed within the interior of the pond, through the ash and into the underlying stream channel deposits. The dewatering system components of interest are shallow vacuum wellpoints installed within cells, deep wells installed through the existing surface liner, ash and underlying aquifer, all within the confines of a perimeter groundwater cut-off wall specifically installed to facilitate dewatering. Well drilling methods were selected to provide detailed mapping of the ash and underlying geology. This presentation is intended to convey the dewatering system installation and proofing aspects and compliment another WOCA presentation focusing on the hydrogeological aspects of the same project case study. An additional WOCA abstract submission will focus on the details of the perimeter cut-off wall.
Document Type
Presentation
Dewatering System Installation Methods for Ash Dewatering and Deep Depressurization
Grand Rapids, Michigan
Dewatering System Installation Methods for Ash Dewatering and Deep Depressurization- A Case Study Authors Mr. Christopher Gee - United States - Dominion Dr. Paul Schmall - United States - Keller Mr. Shawn Coughlin - United States - Keller Mr. Christopher Jones - United States - Haley & Aldrich Inc. Abstract Hydrogeologic conditions of this project require a multi-faceted approach to facilitate not only CCR dewatering but also deep depressurization of underlying highly permeable soils. Previous construction experienced significant and sustained groundwater inflows from beneath the ponded ash because the pond was built over the pre-existing river bed in braided stream channel geology. This previously capped pond will now be closed by removal, requiring access for dewatering installation on top of a previously installed surface liner which will be maintained to prevent precipitation and surface water infiltration over the duration of the project. Unique to this project, wells were installed within the interior of the pond, through the ash and into the underlying stream channel deposits. The dewatering system components of interest are shallow vacuum wellpoints installed within cells, deep wells installed through the existing surface liner, ash and underlying aquifer, all within the confines of a perimeter groundwater cut-off wall specifically installed to facilitate dewatering. Well drilling methods were selected to provide detailed mapping of the ash and underlying geology. This presentation is intended to convey the dewatering system installation and proofing aspects and compliment another WOCA presentation focusing on the hydrogeological aspects of the same project case study. An additional WOCA abstract submission will focus on the details of the perimeter cut-off wall.
