358 Large Scale CCR Dewatering with Geotube® Containers

Overview

A large mid-western coal-fired power plant had accumulated almost 1.5 million cubic yards of coal combustion residuals in their ash lagoon. Recent regulation changes required the plant to remove this ash that had stockpiled over the last several decades. Hydraulically dredging the ash residuals and dewatering using Geotube® containers was chosen as a cost effective means of completing this task.

The Solution

A representative sample of the ash pond sediment was tested by a WaterSolve technician in the facilities laboratory. Dewatering polymers were evaluated based on water release rate, water clarity, and flocculent appearance. In addition, dosing rate(s) were determined during bench-top dewatering experiments and recommendations provided to the contractor during this phase of the project. Solve 162 was determined to be most effective on the ash pond sediment.

Geotube® containers are manufactured from high strength polypropylene fabric and designed to allow effluent water to escape through the pores of the fabric while retaining the chemically-conditioned solids.  120’ circumference Geotube® containers were utilized for this project.

THE RESULT

WaterSolve was tasked to provide the Geotube® containers, polymer, polymer feed equipment, assistance with project design/Geotube® configuration and start-up technical support for the project. Due to the large scale of this production dredging project, a full scale pilot test was implemented to demonstrate the effectiveness of Geotube® container dewatering and to evaluate the achievable dryness of the consolidated ash sediment.