LOS ALAMOS, N.M. - EM’s Los Alamos Field Office (EM-LA) and contractor Los Alamos National Security (LANS) recently developed a safer and more effective solution to collect groundwater samples for the chromium project at Los Alamos National Laboratory.
The improvements are intended to resolve operational and safety challenges of a deep groundwater pump system that collects measurements and samples from hundreds of feet below surface. The system’s heavy tubing bundle had slipped downward through the original support hardware, introducing measurement errors. The weight of the system flattened the bundle’s components, and could potentially cause the lift cable to fail. That cable is part of the winch system used for handling suspended loads.
To secure the tube bundle, EM-LA switched to a new grip used in the electrical industry to support and pull heavy electrical cable. The grip tightens around the tube bundle as the weight of the pump system elongates the grip; the heavier the weight, the stronger the grip.
“The improvements made to the groundwater sampling pump system reduce the number of steps required for pump system installation and removal, reduce system maintenance costs, and most importantly, make handling the systems much safer," LANS Field Services Group Site Operations Manager Steve Maze said. “The innovative improvements were made possible by the invaluable feedback and suggestions provided by my field team regarding pump system handling and safety."
The team also added a large-diameter cable sheave to the winch system to prevent damage to the tubing bundle. Similar to a pulley, the sheave is a free-spinning, grooved wheel used in the electrical industry to pull heavy electrical cable. In contrast to the small-diameter winch rollers, the larger diameter sheave distributes the weight of the pump system over a larger area of the tube bundle and eliminates tube crushing.
The pump system is part of an interim measure approved by the New Mexico Environment Department to ensure a hexavalent chromium plume stays within the laboratory’s boundary while a final remediation approach is evaluated.
Under the interim measure, wells extract the contaminated groundwater, the groundwater is treated using a method called ion exchange, and injection wells add the treated groundwater to the aquifer. Along with extraction, the migration of the plume is controlled by injecting the treated groundwater at the plume’s edge.
The improved pump system supports taking samples from deep piezometers, which monitor and collect water quality data from the plume area.
The project team designed and deployed the improved pump system in the deepest piezometer, and it performed successfully. The team is scheduled to deploy the system in the five remaining piezometers, which are 915 to 1,130 feet below ground surface.
“This new pump system enables us to safely and efficiently collect the data we need to implement the interim measure to control the migration of the chromium plume," EM-LA Manager Doug Hintze said.
Source: U.S. Dept. of Energy, Office of Environmental Management
