On July 9, 2007, Dow’s contractor began positioning equipment on a work barge to begin the preparation of driving temporary sheet piling in the river to delineate the area of highest dioxin contamination. Dow’s contractor has completed construction on the HDPE sediment transport pipeline and has conducted hydrostatic testing of the line. The sediment transport line is approximately 9,000 feet long and will transport sediment slurry from the dredge area in the river to the Geo-Tube dewatering cell.
On-Scene Coordinators (OSC) Jim Augustyn and Brian Schlieger are providing oversight with assistance from U.S. EPA’s START Contractor, Weston Solutions, Inc.
The following tasks have been completed by Dow's contractors during the period of July 23-27, 2007:
Monday, July 23: Dow's contractors continued installation of the temporary sheet pile turbidity barrier above the bridge. Construction continued on the boardwalk between the three Geo-Tube containment cells, including preparation of the Geo-Tube dewatering cell for the application of an asphalt base. Work continues on establishing functional air monitoring stations for obtaining continuous baseline air quality data. A pressure gauge was installed on the HDPE sediment transport pipeline for hydrostatic pressure testing, and the line was filled with river water.
Tuesday, July 24: Installation of the temporary sheet piling continued in the river. Dow mobilized a second crew to expedite the completion of the sheet pile turbidity barrier in the river. Application of an asphalt layer in the Geo-Tube dewatering cell began. Refinement and testing of air monitoring stations continued.
At approximately 12:10 PM, U.S. EPA's START contractor notified the OSC that an oil sheen was developing on the river in the general vicinity of the construction barge. The Dow Field Coordinator was notified and a response team was immediately mobilized to contain the sheen with absorbent boom and pads to prevent further migration downstream. Later in the day, Dow installed a poly-vinyl containment boom that will remain on the river until the completion of the project. The sheen source was identified as coming from a leak in a hydraulic hose from the ”Vibro-Hammer” used to drive sheet piling into the river bed.
Wednesday, July 25: Installation of the temporary sheet piling continued in the river. Staging and assembly of a second work barge began. Application of asphalt layers in the Geo-Tube containment cells continued. The collection of baseline air quality monitoring began. In addition, 24-hour Summa Canister air samples were collected to compare levels against field air monitoring equipment.
Thursday, July 26: Installation of the temporary sheet piling continued in the river. Staging and assembly of a second work barge continued. The application of asphalt in the Geo-Tube containment cells was completed. Baseline air quality monitoring continued and the 24-hour Summa canister samples were collected.
Friday, July 27: Installation of the temporary sheet piling above the bridge is nearly complete. Staging and assembly of a second work barge continued. Dow’s contractors continue to prep the containment cells and began hydro-seeding the perimeter of the cells. Air monitoring throughout the project area continues. A visual inspection of the sediment transport line during hydrostatic testing discovered a suspect “indentation” on the HDPE line. The defective section of the line will be removed and replaced. Installation and testing of turbidity monitors in the river began. A turbidity monitor will be placed upstream and immediately downstream of the of the project area. The downstream monitor will measure any potential turbidity increase resulting from dredging operations.
Installation of sheet piling above the bridge is nearly complete. The sheet piling will be driven down to established elevations to complete the installation. Turbidity monitors will be placed in the river to monitory potential increases in turbidity that may result from excavation of material from the river bank adjacent to the RGIS system.
Rip rap and large debris will be mechanically excavated from the existing RGIS sheet piling within the turbidity barrier area. The excavated material will be placed over the RGIS system and allowed to drain. Once sufficiently free of water, the excavated material will be transported to Dow’s Salzburg Road Landfill for disposal. When all excavated material is properly disposed of, a layer of clean gravel will be placed over the length of the RGIS system.
Construction on the Geo-Tube containment cells and air monitoring stations will continue. Geo-Tubes and associated connections to the sediment transport line will be completed in preparation for dredging operations to start.
Once all rip rap and large debris are removed from the work area, installation of new permanent sheet piling for the RGIS system will begin. Dredging of contaminated sediment cannot begin until the permanent sheet piling is in place.
The second sheet piling crew will continue to install temporary sheet piling under the bridge. The temporary sheet piling will be installed along the entire length of the project area and will end adjacent to the Dow Dam.
U.S. EPA has completed its review and has provided comments to Dow on the Draft Work Plan for the site. Dow is preparing revisions and will resubmit changes by July 31, 2007.
U.S. EPA has completed its review of the site-specific Health and Safety Plan (HASP). Dow will incorporate U.S. EPA’s recommendations into the HASP.
|
