DESIGN AND MODELING TO DEWATER​ A PARTIALLY COMPOSITE-COVERED ASH POND.pdf

Michael Thornbrue, Atlas Technical Consultants

Description

DESIGN AND MODELING TO DEWATER A PARTIALLY CLOSED ASH POND Authors Mr. Michael Thornbrue - United States - Atlas Technical Consultants Abstract An Electrical Power Supplier in the Midwest retained Atlas Technical Consultants (Atlas) to design a system to dewater a partially closed ash pond and predict its performance over a period of five (5) years. Prior to January 2022, the client began closure of the ash pond and completed installation of a composite cover over about 40% of the pond’s area. Atlas investigated the pond’s geology and concluded that the bottom and perimeter embankments consist of lean clay (k≈5x10‑8 cm/s) and the water level within the ash was about 20 feet below ground surface and about 22 feet above the bottom of ash. Atlas designed a system of eight (8) horizontal extraction wells with over 6,500 feet of screen interval that were installed near the bottom of ash to remove free liquids and readily separable pore water. Following completion of a design package, Atlas prepared a Visual Modflow model of the ash pond to simulate dewatering over a period of five (5) years. The modeling indicated that the horizontal wells would reduce the water level within the ash to less than three (3) feet above the bottom of ash and create an inward gradient within the pond.

 
May 15th, 9:30 AM May 15th, 10:00 AM

DESIGN AND MODELING TO DEWATER​ A PARTIALLY COMPOSITE-COVERED ASH POND.pdf

Grand Rapids, Michigan

DESIGN AND MODELING TO DEWATER A PARTIALLY CLOSED ASH POND Authors Mr. Michael Thornbrue - United States - Atlas Technical Consultants Abstract An Electrical Power Supplier in the Midwest retained Atlas Technical Consultants (Atlas) to design a system to dewater a partially closed ash pond and predict its performance over a period of five (5) years. Prior to January 2022, the client began closure of the ash pond and completed installation of a composite cover over about 40% of the pond’s area. Atlas investigated the pond’s geology and concluded that the bottom and perimeter embankments consist of lean clay (k≈5x10‑8 cm/s) and the water level within the ash was about 20 feet below ground surface and about 22 feet above the bottom of ash. Atlas designed a system of eight (8) horizontal extraction wells with over 6,500 feet of screen interval that were installed near the bottom of ash to remove free liquids and readily separable pore water. Following completion of a design package, Atlas prepared a Visual Modflow model of the ash pond to simulate dewatering over a period of five (5) years. The modeling indicated that the horizontal wells would reduce the water level within the ash to less than three (3) feet above the bottom of ash and create an inward gradient within the pond.