Search Results

Advanced search parameters have been applied.

100-D Area In Situ Redox Treatability Test for Chromate-Contaminated Groundwater

Description: A treatability test was conducted for the In Situ Redox Manipulation (ISRM) technology at the 100 D Area of the U. S. Department of Energy's Hanford Site. The target contaminant was dissolved chromate in groundwater. The ISRM technology creates a permeable subsurface treatment zone to reduce mobile chromate in groundwater to an insoluble form. The ISRM permeable treatment zone is created by reducing ferric iron to ferrous iron within the aquifer sediments, which is accomplished by injecting aqueous sodium dithionite into the aquifer and then withdrawing the reaction products. The goal of the treatability test was to create a linear ISRM barrier by injecting sodium dithionite into five wells. Well installation and site characterization activities began in spring 1997; the first dithionite injection took place in September 1997. The results of this first injection were monitored through the spring of 1998. The remaining four dithionite injections were carried out in May through July of 1998.These five injections created a reduced zone in the Hanford unconfined aquifer approximately 150 feet in length (perpendicular to groundwater flow) and 50 feet wide. The reduced zone extended over the thickness of the unconfined zone. Analysis of post-emplacement groundwater samples showed concentrations of chromate, in the reduced zone decreased from approximately 1.0 mg/L before the tests to below analytical detection limits (<0.007 mg/L). Chromate concentrations also declined in downgradient monitoring wells to as low as 0.020 mg/L. These data, in addition to results from pre-test reducible iron characterization, indicate the barrier should be effective for 20 to 25 years. The 100-D Area ISRM barrier is being expanded to a length of up to 2,300 ft to capture a larger portion of the chromate plume.
Date: October 12, 2000
Creator: Williams, Mark D.; Vermeul, Vincent R.; Szecsody, James E. & Fruchter, Jonathan S.
Partner: UNT Libraries Government Documents Department

Need and Options for Subnational Scale Land-Use and Land-Cover Scenarios for the United States

Description: "This report summarizes discussions during a workshop of users and producers of land use and land cover (LULC) scenarios convened by the Scenarios and Interpretive Science Coordinating Group of U.S. Global Change Research Program (USGCRP) on June 25-27, 2014."
Date: January 2015
Creator: Brown, Daniel; Delgado, Alison; Moss, Richard & Sedano, Fernando
Partner: UNT Libraries Government Documents Department

Clean Water Act Section 401 Water Quality Certification: A Water Quality Protection Tool For States and Tribes

Description: A handbook that describes Clean Water Act Section 401 certification authorities, the different ways certain states and tribal programs used certification, and how state and tribal certification programs leverage available resources to operate their certification programs.
Date: April 2010
Creator: U.S. Environmental Protection Agency
Partner: UNT Libraries Government Documents Department

Identifying Chemical Reactivity Hazards: Preliminary Screening Method

Description: "The purpose of this alert is to introduce small and medium-sized facilities to a simple method developed by the Center for Chemical Process Safety (CCPS), to screen facilities for chemical reactivity hazards."
Date: May 2004
Creator: United States. Environmental Protection Agency. Office of Solid Waste and Emergency Response.
Partner: UNT Libraries Government Documents Department

NCA Report Series, Volume 6: Scenarios for Research and Assessment of Our Climate Future: Issues and Methodological Perspectives for U.S. National Climate Assessment

Description: "This document reports on a workshop held in December 2010 in Arlington, Virginia to explore needs, options, and research for the development of scenarios to support science and assessment of climate and global change over the coming decades."
Date: unknown
Partner: UNT Libraries Government Documents Department
Back to Top of Screen