The U.S. Army Corps of Engineers is responsible for the environmental stewardship of our Nations waterways by restoring, managing, and enhancing ecosystems, locally and regionally.
The Pittsburgh District Area of Responsibility (AOR) includes the watershed areas of the Allegheny, Monongahela, and Upper Ohio Rivers. The Mahoning River is part of this AOR.
Section 312 of the Water Resources Development Act of 1990 allows the Corps to remove and remediate contaminated sediments in and adjacent to navigable waters.
Project Study Area
- Lower 45 miles of the river
- 33 miles in Ohio, from the Oh/PA state line to the Leavittsburg Dam
- 12 miles in Pennsylvania, from confluence with the Shenango to form the Beaver River south of New Castle to the OH/PA State line
- 12 low-head dams, constructed for the canal then modified to create pools for steel industry cooling and process water.
Feasibility Study
Mahoning River, Ohio
Project Life Cycle
- Reconnaissance Study
- Start - January 1998
- Complete - May 1999
- Feasibility Study
- Start - March 2002
- Complete - July 2004 (scheduled)
Feasibility Study - The Report
- Plan Formulation and Evaluation
- National Environmental Policy Act (NEPA) Document
- Engineering Technical Appendix
- Real Estate Plan
Main Report and NEPA Document
The Main Report consists of a narrative of the plan formulation and evaluation. It will identify the recommended plan and have a detailed plan formulation and analysis to support the recommendation.
The NEPA document, which is either an Environmental Assessment or Environmental Impact Statement, will be incorporated into the main report and is usually printed on color paper to distinguish it from the main report. The NEPA document will evaluate the impacts of the various plans and the recommended plan.
An integrated report may be prepared, which incorporates the plan formulation and environmental documentation into one main report. The advantages of this format is the reduction of duplication of effort.
Engineering Technical Appendix
The Engineering Technical Appendix is a stand alone report which documents the engineering features of the study. Depending upon the scope of study it may actually be several reports. Engineering studies will include surveying and mapping, hydrology and hydraulics, geotechnical investigations, general engineering site investigations, sediment quality analysis, water quality analysis, and cost engineering analysis.
Real Estate Plan (REP)
The Real Estate Plan will identify the real estate requirements for each plan formulated and determine a dollar value of the land required for that specific plan. Real estate costs are considered a project cost and could be a determining factor in which a plan is recommended.
Potential Alternatives
Range of Alternatives
No action (With-Out-Project)Alternative
Minimum Alternative - Remove In-River Sediments Only
Maximum Alternative - Remove In-River and Bank Sediments
Intermediate Alternative - Bioremediation/Capping (?)
River Restoration Options
Removal Technologies
Two general types of dredges, mechanical and hydraulic, and including special dredges designed for environmental projects.
Non Removal Technologies
- Two general types, those that isolate or cap sediments from aquatic environments and in-place treatment
- In place treatment includes bioremediation, which is a managed or spontaneous technique where microbiological processes are used to degrade or transform contaminants to less toxic or nontoxic forms.
Existing Environmental Quality
Environmental quality can be measured several ways. By looking at the quality of habitat and the biodiversity present in the study area, we can determine how the project area compares with the model reach.
Physical Habitat...
...is measured with the Qualitative Habitat Evaluation Index (QHEI). This index looks at the quality of substrate, instream cover, channel morphology, riparian vegetation, gradient, and pool, run and riffle complexes.
Project Area:
The river's physical habitat is impacted by 10 dams. In free-flowing segments below the dams, QHEI scores meet or exceed the criterium used to define a healthy habitat while QHEI scores in impounded segments near the dam are lower and do not exceed the criterium.
Fish Communtities...
...are measured with the Index of Biotic Integrity (IBI) and the Modified Index of Well Being (mIWB). These indices consider species richness and composition, trophic composition, and fish abundance and condition.
Project Area:
The fish communities at most of the sampling sites in the study area had IBI and mIwb scores that are categorized as very poor, poor, or fair.
Macroinvertebrate Communities...
...are measured with the Invertebrate Community Index (ICI). This index considers species richness and composition and trophic composition.
Project Area:
Macroinvertebrate communities throughout the study area had low ICI scores; the communities were characterized as poor or fair at most sampling sites.
Despite a healthy physical habitat in free-flowing segments, conditions of the Mahoning River in the Project Area do not support diverse or healthy fish or macroinvertebrate populations.
Dredging
Hydraulic Dredging
Hydraulic dredging is a form of sediment removal. It is accomplished by a piece of equipment that floats on the water with a cutter head or auger to agitate the material. It is then sucked up by a large pump and pushed through a pipeline to remote sediment basin or spoil site. Silt curtains are used to protect downstream water.
Mechanical Dredging
Mechanical dredging is accomplished by many methods. Long reach backhoes and draglines are the most widely used. Backhoes or mechanical buckets are used to remove the material from the bottom and place it directly into trucks that haul it to placement areas. The material can also be placed on shore from backhoe or dragline if the placement site is close enough.
Capping and Disposal
Capping of Contaminated Sediments
Controlled placement of various material (e.g., sand, fill, gravel/cobbles, geotextile material, etc.) To physically isolate sediments/bank materials from water. Typical process options include: Multimedia cap, sand cap, Aquablock etc.
Contaminated Sediments Disposal
Depending on contaminant concentrations disposal options may include:
Beneficial use at Brownfield Sites
Residual landfill placement at cammercially operated landfills
Recycling - incinerationg the sediments to remove the contaminants and using the material as aggregate
Land Fill Cover - commercially operated land fill sites fro municipal waste need land fill cover. The contaminated sediments may be treated then used to meet this need
Construct a new landfill to handle the disposal needs for the project.
ALL INFORMATION TAKEN FROM THE US ARMY CORPS OF ENGINEERS, PITTSBURGH DISTRICT, AND EASTGATE REGIONAL COUNCIL OF GOVERNMENTS "PROJECT OVERVIEW SUMMARY"
