Comment: Did you know that the nuke pusher VA Tech is doing the same study? Who is paying for their study, the nukes or the taxpayers of VA since it is a State school?
Tuesday, March 22, 2011 6:08 PM EDT
The City of Virginia Beach (City) commissioned a preliminary assessment to determine if a catastrophic failure of a mill tailings containment cell in the viciniy of the potential uranium mining locations at Coles Hill would be a cause for concern to the City’s drinking water source at Lke Gaston.
This preliminary assessment relied on best available data from various sources because detailed site-specific data such as the design of tailings containment structure and likely characteristics of the tailings were not availabl.
Virginia Uranium, Inc., the owner of the mining leases at Coles Hill, informed the City that no new site-specific data have been developed other than what was published in a 1983 report titled “An Evaluation of Uranium Development in Pittsylvania County, Virginia” by Marline Uranium Corporation and Union Carbide Corporation (Marline Report).
As a result, the preliminary assessment used a range of published data associated with uranium mining in the United States and a number of ailure scenarios to develop an understanding of the range of potential impacts that could result.
The City’s preliminary assessment utilized a fully verified and validated one-dimensional river model to evaluate potential impacts of a uranium tailings containment failure on downstream drinking water sorces.
The same one-dimensional modeling techniques were utilized for stretches of the naturally flowing rivers as well as for sections altered by anmade dams such as the reservoir on the Banister River at Halifax.
This representation of manmade dams is a standard practice, especially for small reservoirs such as the one impounded by Banister Dam. In areas impounded by this dam, the reduced flow rates in the wider and deeper cross sections of the river reasonably simulate the trapping of larger sediment transported in the water column together with any attached contaminants.
However, suspended sediments carrying a considerable fraction of the pollutants would still be transported over the dam and flushed dowstream. In addition, dissolved contaminants (primarily radium) would not be affected by the presence of a dam.
The river models developed for the City’s preliminary assessment used a combination of stream cross section data obtained from he Federal Emergency Management Agency (FEMA), the Virginia Department of Transportation, and the U.S. Army Corps of Engineers, from a range of dates.
These data were the most recent and best available cross-sectional data for the rivers.
As of today, no newer published FEMA cross section data are available although new Flood Insurance Rate Maps (FIRMs) have been published recently for Pittsylvania and Halifax Counties. As detailed in the Flood Insurance Study Reports dated September 29, 2010 (for Pittsylvania County) and October 16, 2009 (for Halifax County) that accompany these FIRMs, the delineations for Banister River are based on hydraulic model simulations and cross sections from the 1970s. Although it is possible that stream-bed topography might have changed during the past 35 years, a comparison of the cross sections at the Halifax and Randolph USGS gaging stations dated November 2009 revealed good agreemen with the FEMA data.
At the time the study was initiated, specific details for the uranium tailings management facility planned for the Coles Hill mine were not available; however, the Marline Report provided a conceptual design for the uranium tailings management facility based on 1983 NRC regulations.
The Marline report proposed an above-grade, ring-type impoundment system encompassing approximately 220 acres. Current Nuclear Regulatory Commission (NRC) regulations and the Regulatory Guide 3.11 “Design, Construction, and Inspection of Embankment Retention Systems at Uranium Recovery Facilities” specify a maximum surface area of 40 acres for phased disposal in uranium tailings retention facilities.
Therefore, the City study used a range of designs with varying impoundment dam heights and corresponding storage volumes considering requrements outlined in the NRC Guide 3.11.
Although NRC’s regulatory guide suggests that the “prime option” for the disposal of tailings is placement below grade, it also states that above grade storage must be minimized by excavation to the maximum extent reasonably achievable given the eologic and hydrologic conditions at a site.
The City’s study assumed that storage of the tailings below the surface would not be viable based on the subsurface investigaions reported in the Marline Report for the site, which states “Below grade tailings disposal is not practical in this area because of high water table” (Reference - Section E.3.4.2, Page E.3-11).
The study primarily relied on computational models of the rivers flowing from the potential mine sites to the Kerr Reservoir (which discharges to Lake Gaston) to simulate potential impacts to the river and reservoir system.
The models were developed and calibrated to mimic the historic flows of the associated rivers. More detailed site data (such as the sediment grain size and density, radioactivity in tailings, water velocities, chemical composition of water and temperature, the current streambed and reservoir bottom topography) and the use of more advanced models (such as a two-dimensional model for the reservoirs) will help to refine the results and provide better understanding of the movement and residence time of radioactivity throughou the study area.
However, it is highly unlikely that they will significantly change the overall conclusions presented in the preliminary assessment.
A panel of independent experts reviewed the data used as well as the techniques to complete the preliminary assessment.
As a result of the study process and the feedback from the expert panel, the preliminary assessment provides a sound conclusion that a catastrophic failure of an above-ground uranium mining tailings impoundment has the potential to contaminate the water supply to the City of Virginia Beach and ther communities that rely on water from Banister River and the Lake Gaston source water.
The City’s goal is to objectively determine potential impacts of uranium mining to its drinking water supplies.
As new data becomes available, it can be utilized to refine analyses and improve our understanding of how radioactive materials and uranium could move along he rivers and flush through the reservoirs downstream.
Thomas Leahy
Department of Public Utilities, City of Virginia Beach
Read more:
http://vancnews.com/articles/2011/03/22/south_hill/opinion/opinion05.txt
