Back to Basics

Paul Schmall, Keller

Description

CCR Dewatering – Back to the Basics Authors Dr. Paul Schmall - United States - Keller Abstract The increase in CCR pond closure activity spurred by the EPA’s 2015 rule publication has created a tremendous opportunity to innovate with respect to traditional methods of safely working around and on saturated CCR material. The volume of work and the speed at which it must be completed requires that the industry adapt in order to meet regulatory timelines. One technique that has been successfully implemented is the use of conventional construction dewatering technology to stabilize CCR by reducing and controlling pore pressures. This paper offers a “back to basics” look at the fundamentals of how dewatering tools such as wells, wellpoints, and eductors work. It is intended for those who are new to this technology or need a refresher. Historically, CCR has been dewatered by creating ditches and sumps to direct surface and pore water to pumps. This has the advantage of being inexpensive. However, this method is also slow, can worsen water quality by creating opportunities for oxygen to mix with the water, and may require equipment to operate on the CCR, potentially creating an unsafe condition. Wells, wellpoints, and eductors (ejectors) are commonly used as dewatering tools in the underground construction industry. These tools have proven themselves in the CCR pond closure industry in that they are able to drain pore water rapidly, they may be used to positively control pore pressures to stabilize work surfaces and slopes, they may be installed safely, and, if operated correctly, they will not have a detrimental impact on water chemistry.

 
May 14th, 11:30 AM May 14th, 12:00 PM

Back to Basics

Grand Rapids, Michigan

CCR Dewatering – Back to the Basics Authors Dr. Paul Schmall - United States - Keller Abstract The increase in CCR pond closure activity spurred by the EPA’s 2015 rule publication has created a tremendous opportunity to innovate with respect to traditional methods of safely working around and on saturated CCR material. The volume of work and the speed at which it must be completed requires that the industry adapt in order to meet regulatory timelines. One technique that has been successfully implemented is the use of conventional construction dewatering technology to stabilize CCR by reducing and controlling pore pressures. This paper offers a “back to basics” look at the fundamentals of how dewatering tools such as wells, wellpoints, and eductors work. It is intended for those who are new to this technology or need a refresher. Historically, CCR has been dewatered by creating ditches and sumps to direct surface and pore water to pumps. This has the advantage of being inexpensive. However, this method is also slow, can worsen water quality by creating opportunities for oxygen to mix with the water, and may require equipment to operate on the CCR, potentially creating an unsafe condition. Wells, wellpoints, and eductors (ejectors) are commonly used as dewatering tools in the underground construction industry. These tools have proven themselves in the CCR pond closure industry in that they are able to drain pore water rapidly, they may be used to positively control pore pressures to stabilize work surfaces and slopes, they may be installed safely, and, if operated correctly, they will not have a detrimental impact on water chemistry.