Please use this identifier to cite or link to this item: https://hdl.handle.net/11681/48174
Title: Supplemental Environmental Assessment with Finding of No Significant Impact : Removal of Rock Pinnacles and Outcroppings Considered to be Navigation Obstructions During Low-Flow Periods on the Middle Mississippi River
Authors: United States. Army. Corps of Engineers. St. Louis District
Keywords: Mississippi River
Inland navigation
Environmental management
Environmental management
Publisher: United States. Army. Corps of Engineers. St. Louis District.
Abstract: This Environmental Assessment is a supplement to “Environmental Assessment with Draft Finding of No Significant Impact - Explosive Removal of Rock Pinnacles and Outcroppings Considered to be Navigation Obstructions During Low-Flow Periods on the Middle Mississippi River” dated November 2006; and Tier II Supplemental Environmental Assessment with Draft Finding of No Significant Impact - Removal of Rock Pinnacles and Outcroppings Considered to be Navigation Obstructions During Low-Flow Periods on the Middle Mississippi River” dated July 2009. The FONSI for the 2006 EA was signed on 14 February 2007; the FONSI for the 2009 SEA was signed on 30 September 2009; these documents are incorporated by reference, and can be found online at http://www.mvs.usace.army.mil/pm/pm-reports.html. During 1988, an extremely low-water year, it was realized that there were a number of rock pinnacles and rock shelves that were a potential hazard to commercial navigation traffic on the Middle Mississippi River (MMR). These rock hazards were removed during 1988-1999 using explosive removal. Validation of safe elevations was conducted using an I-beam attached to two cables. The I-beam was used to sweep the removal areas after an area was lowered by blasting. The equipment used to delineate obstructions and to verify their removal was primitive by today’s standards. With the potential for another extremely low-water period looming in late 2006, new state-of-the-art hydrographic multibeam surveys were conducted and a number of rock pinnacles and rock outcroppings, which were missed by the rock removal efforts in 1988-1999, were detected. These remnants that were missed during the previous blasting pose a potential hazard to commercial boat traffic (safety hazard), a threat to close the navigation system due to low water (economic impact), and a threat to the environment (hazardous spill) if there were a towboat grounding. The proposed 2006 Rock Removal project was not executed because the U.S. Army Corps of Engineers (USACE) St. Louis District (MVS) was unable to find a contractor willing to conduct the work within a reasonable cost with reference to the Government Cost Estimate at that time. The proposed 2009 rock removal project was halted after the grinding method used by the contractor was determined to be ineffective. The purpose of this Supplemental Environmental Assessment (SEA) is to provide the public with information concerning proposed additional rock removal locations which were not addressed in the 2006 or 2009 rock removal project EAs, and to assess the impacts of the additional rock removal.
Description: Supplemental Environmental Assessment and Finding of No Significant Impact
Rights: Approved for Public Release; Distribution is Unlimited
URI: https://hdl.handle.net/11681/48174
Appears in Collections:Environmental Documents

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