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Title: Solar-Powered Air Stripping at the Rocky Flats Site, Colorado - 12361

Abstract

The U.S. Department of Energy's Rocky Flats Site (the Site), near Denver, Colorado, is a former nuclear weapons facility that was constructed beginning in 1951. With the end of the Cold War, the Site was cleaned up and closed in 2005. Four gravity-driven groundwater treatment systems were installed during cleanup, and their continued operation was incorporated into the final remedy for the Site. All utilities, including electrical power, were removed as part of this closure, so all Site electrical power needs are now met with small solar-powered systems. The Mound Site Plume Treatment System (MSPTS) was installed in 1998 as an innovative system based on zero-valent iron (ZVI). Groundwater flow from the Mound source area containing elevated concentrations of volatile organic compounds (VOCs), primarily in the tetrachloroethene (PCE)-trichloroethene (TCE) family of chlorinated solvents, is intercepted by a collection trench and routed to twin ZVI treatment cells. Later, in 2005, remediation of VOC-contaminated soils at a second up-gradient source area included adding an electron donor to the backfill to help stimulate biodegradation. This reduced concentrations of primary constituents but caused down-gradient groundwater to contain elevated levels of recalcitrant degradation byproducts, particularly cis-1,2-dichloroethene and vinyl chloride. A gravel drain installed as partmore » of the 2005 remediation directs contaminated groundwater from this second source area to the MSPTS for treatment. This additional contaminant load, coupled with correspondingly reduced residence time within the ZVI media due to the increased flow rate, resulted in reduced treatment effectiveness. Elevated concentrations of VOCs were then detected in MSPTS effluent, as well as in surface water at the downstream performance monitoring location for the MSPTS. Subsequent consultations with the Site regulators led to the decision to add a polishing component to reduce residual VOCs in MSPTS effluent. Initially, several alternatives such as commercial air strippers and cascade aerators were evaluated; resulting cost estimates exceeded $100,000. After several simpler alternatives were considered and prototype testing was conducted, the existing effluent metering manhole was converted to house a spray-nozzle based, solar-powered air stripper, at a cost of approximately $20,000. About two-thirds of this cost was for the solar power system, which was initially designed to only provide power for 12 hours per day. Performance data are being collected and adjustments made to optimize the design, determine maintenance requirements, and establish power needs for continuous operation. Analytical data confirm the air stripper is sharply reducing concentrations of residual contaminants. (authors)« less

Authors:
 [1]
  1. S.M. Stoller Corporation, Rocky Flats Site, 11025 Dover Street, Suite 1000, Westminster, Colorado 80021 (United States)
Publication Date:
Research Org.:
WM Symposia, 1628 E. Southern Avenue, Suite 9-332, Tempe, AZ 85282 (United States)
OSTI Identifier:
22293613
Report Number(s):
INIS-US-14-WM-12361
TRN: US14V1269115137
Resource Type:
Conference
Resource Relation:
Conference: WM2012: Waste Management 2012 conference on improving the future in waste management, Phoenix, AZ (United States), 26 Feb - 1 Mar 2012; Other Information: Country of input: France; 4 refs.
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; BIODEGRADATION; COLORADO; GROUND WATER; MONITORING; NUCLEAR WEAPONS; POWER SYSTEMS; SOLVENTS; VOLATILE MATTER; VOLATILITY

Citation Formats

Boylan, John A. Solar-Powered Air Stripping at the Rocky Flats Site, Colorado - 12361. United States: N. p., 2012. Web.
Boylan, John A. Solar-Powered Air Stripping at the Rocky Flats Site, Colorado - 12361. United States.
Boylan, John A. 2012. "Solar-Powered Air Stripping at the Rocky Flats Site, Colorado - 12361". United States.
@article{osti_22293613,
title = {Solar-Powered Air Stripping at the Rocky Flats Site, Colorado - 12361},
author = {Boylan, John A.},
abstractNote = {The U.S. Department of Energy's Rocky Flats Site (the Site), near Denver, Colorado, is a former nuclear weapons facility that was constructed beginning in 1951. With the end of the Cold War, the Site was cleaned up and closed in 2005. Four gravity-driven groundwater treatment systems were installed during cleanup, and their continued operation was incorporated into the final remedy for the Site. All utilities, including electrical power, were removed as part of this closure, so all Site electrical power needs are now met with small solar-powered systems. The Mound Site Plume Treatment System (MSPTS) was installed in 1998 as an innovative system based on zero-valent iron (ZVI). Groundwater flow from the Mound source area containing elevated concentrations of volatile organic compounds (VOCs), primarily in the tetrachloroethene (PCE)-trichloroethene (TCE) family of chlorinated solvents, is intercepted by a collection trench and routed to twin ZVI treatment cells. Later, in 2005, remediation of VOC-contaminated soils at a second up-gradient source area included adding an electron donor to the backfill to help stimulate biodegradation. This reduced concentrations of primary constituents but caused down-gradient groundwater to contain elevated levels of recalcitrant degradation byproducts, particularly cis-1,2-dichloroethene and vinyl chloride. A gravel drain installed as part of the 2005 remediation directs contaminated groundwater from this second source area to the MSPTS for treatment. This additional contaminant load, coupled with correspondingly reduced residence time within the ZVI media due to the increased flow rate, resulted in reduced treatment effectiveness. Elevated concentrations of VOCs were then detected in MSPTS effluent, as well as in surface water at the downstream performance monitoring location for the MSPTS. Subsequent consultations with the Site regulators led to the decision to add a polishing component to reduce residual VOCs in MSPTS effluent. Initially, several alternatives such as commercial air strippers and cascade aerators were evaluated; resulting cost estimates exceeded $100,000. After several simpler alternatives were considered and prototype testing was conducted, the existing effluent metering manhole was converted to house a spray-nozzle based, solar-powered air stripper, at a cost of approximately $20,000. About two-thirds of this cost was for the solar power system, which was initially designed to only provide power for 12 hours per day. Performance data are being collected and adjustments made to optimize the design, determine maintenance requirements, and establish power needs for continuous operation. Analytical data confirm the air stripper is sharply reducing concentrations of residual contaminants. (authors)},
doi = {},
url = {https://www.osti.gov/biblio/22293613}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Jul 01 00:00:00 EDT 2012},
month = {Sun Jul 01 00:00:00 EDT 2012}
}

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