Author(s): James D. Quadrini; Hung Tao Shen; George D. Ashton; Philip T. Hendershot
Linked Author(s): George Ashton, Hung Tao Shen
Keywords: No keywords
Abstract: Subsequent to the occurrence of the 2003 scour event in the Grasse River, Alcoa conducted an extensive river ice investigation to obtain the information needed to understand the impact of icerelated scour on long-term remedial options for managing PCB-containing sediments in the river. A pier-type ice control structure (ICS) was one potential effective technology identified during this investigation. Several studies were conducted to help support the evaluation and design of such a structure, including numerical and physical model studies. The numerical and physical model studies were conducted using the 2003 ice scour event as the design event. This event was considered an appropriate design event for the evaluation of the Grasse River ICS based on the severity of the 2002-2003 winter relative to prior winters, extent of scour observed during the 2003 event relative to historic events, the height of tree scars resulting from the 2003 ice jam relative to the historic record, and the volume of information that was generated for the 2003 event. In addition to this design event, several combinations of river flow and ice supply with estimated recurrence intervals of approximately 1 in 100 years were tested to account for the inherent year-to-year variability associated with these parameters. The selection of these 100-year events was based on a combined probability analysis performed with over 80 years of site data. Conservatism was incorporated into the design event and 100-year event conditions used in the modeling studies. This paper details the approach used to define the design event and 100-year event conditions used in the numerical and physical modeling analyses of ice control alternatives for the lower Grasse River. The findings presented in this paper represent work in progress only, as the final remedy at the Grasse River site has yet to be chosen.
Year: 2008