Dewatering Pilot Tests for Geotechnical Investigation.pdf

Paul Schmall, Keller

Description

Dewatering Pilot Tests for Geotechnical Investigation Authors Dr. Paul Schmall - United States - Keller Abstract Pore water dewatering using wells, wellpoints, and other devices has become a standard tool for facilitating pond closure, both for improving stability and safety on previously saturated CCR surfaces, and for improving excavatability and general workability of CCR material. However, most pond geotechnical investigations are not designed to produce the parameters required to properly design a pore water dewatering system. Parameters such as well pumping yields, the CCR’s hydraulic conductivity, storativity, and the influence of native groundwater or surface water bodies must all be taken into account in design. The resulting well spacing, system flow rate, expected radius of influence are all greatly affected by these parameters. What’s more, given the nature of how CCR is sluiced or deposited into ponds, these parameters will almost certainly vary over the pond’s depth and areal extent. The details of the dewatering system design will have knock on effects that affect the rest of the pond closure including the size of any required water treatment system, and the speed at which water and CCR may be practically removed from the pond. This paper will discuss how dewatering pilot tests may be used as a part a pond closure’s geotechnical investigation to narrow the range of the parameters listed above, and to provide practical experience and observations about how the CCR’s pore water reacts to pumping. This results in more accurate initial estimates of the actual effort required, leveling the playing field for bidders and project owners alike. Further, a dewatering pilot test need not be a stand alone event. Rather, it may be advantageous to consider the pilot test as part of a continuum of dewatering effort for a particular pond, adding to it after some analysis of the pilot data.

 
May 16th, 8:30 AM May 16th, 9:00 AM

Dewatering Pilot Tests for Geotechnical Investigation.pdf

Grand Rapids, Michigan

Dewatering Pilot Tests for Geotechnical Investigation Authors Dr. Paul Schmall - United States - Keller Abstract Pore water dewatering using wells, wellpoints, and other devices has become a standard tool for facilitating pond closure, both for improving stability and safety on previously saturated CCR surfaces, and for improving excavatability and general workability of CCR material. However, most pond geotechnical investigations are not designed to produce the parameters required to properly design a pore water dewatering system. Parameters such as well pumping yields, the CCR’s hydraulic conductivity, storativity, and the influence of native groundwater or surface water bodies must all be taken into account in design. The resulting well spacing, system flow rate, expected radius of influence are all greatly affected by these parameters. What’s more, given the nature of how CCR is sluiced or deposited into ponds, these parameters will almost certainly vary over the pond’s depth and areal extent. The details of the dewatering system design will have knock on effects that affect the rest of the pond closure including the size of any required water treatment system, and the speed at which water and CCR may be practically removed from the pond. This paper will discuss how dewatering pilot tests may be used as a part a pond closure’s geotechnical investigation to narrow the range of the parameters listed above, and to provide practical experience and observations about how the CCR’s pore water reacts to pumping. This results in more accurate initial estimates of the actual effort required, leveling the playing field for bidders and project owners alike. Further, a dewatering pilot test need not be a stand alone event. Rather, it may be advantageous to consider the pilot test as part of a continuum of dewatering effort for a particular pond, adding to it after some analysis of the pilot data.