Late on Friday, November 9, 2007, Dow notified U.S. EPA that preliminary data for a sediment sample collected from within the channel of the Saginaw River was in excess of 1.6 parts per million (ppm) Dioxin TEQ. This is the highest TEQ analytical result recorded for either the Tittabawassee or Saginaw Rivers. On November 11, 2007, U.S. EPA issued a verbal General Notice Letter of Potential Liability to Dow.
On Monday, November 12, 2007, U.S. EPA, MDEQ and Dow representatives met at Wickes Park in the City of Saginaw to review site conditions and discuss U.S. EPA’s expectations for the conduct of an expedited time-critical removal action. An Administrative Order by Consent was signed by U.S. EPA and Dow on November 15, 2007, for the performance of the removal. Dow has collected physical site data such as river depth, velocity measurements, channel profile measurements, and collected additional sediment samples for waste characterization and dewatering studies.
The following tasks have been completed by Dow’s contractor during the period from November 15, 2007, through December 2, 2007:
On Thursday, November 15, 2007, and Monday, November 19, 2007, sediment sampling activities were conducted to further delineate the extent of the contaminated sediment within the river. Core samples were collected from GPS surveyed locations. The cores were split apart and boring logs were completed for each of the cores. Sediment samples were collected from the cores and sent to a laboratory for dioxin analysis.
Divers surveyed the river bottom within the contaminated area and recorded any debris or irregularities within the proposed removal area.
On Monday, November 26, 2007, Site mobilization and setup continued. Dow’s contractors completed the installation of perimeter fencing, completed asphalting the containment area and the Site access road.
On Tuesday, November 27, 2007, Site mobilization and setup continued. Dow’s contractors began the setup and installation of the temporary water treatment system. A dive barge was constructed and dive and dredge equipment were placed on the barge. The barge crew installed U.S. Coast Guard (USCG) approved lighting and safety controls on the barge. Site crew and office trailers were setup on Site. Divers surveyed the perimeter of the proposed dredging area and placed buoys on the surface of the river to mark the locations.
On Wednesday, November 28, 2007, Site mobilization and setup continued. Dow’s contractors collected an additional sediment sample just outside of the southeast portion of the proposed dredge area in order to further delineate the extent of sediment contamination. Dow’s contractors continued with the setup and installation of the water treatment system. Setup of the solids conveyor system and the dewatering system was initiated.
USCG inspected the barge and approved the barge light and safety controls. USCG also approved Dow’s proposed plan to temporarily anchor the barge in the center of the river throughout the removal operation.
Divers assisted with the placement of the concrete anchors around the perimeter of the proposed dredge area that will be used to anchor the barge in place during the removal operation.
On Thursday, November 29, 2007, and Friday November 30, 2007, Site mobilization and setup continued. Dow’s contractors continued with the setup and installation of the water treatment, conveyor belt and sediment dewatering systems.
On Friday, November 30, 2007, Site mobilization and setup continued. Dow’s contractors continued with the setup and installation of the water treatment, conveyor belt and dewatering systems. Crews continued setting up temporary shelters and roofing over the water treatment, dewatering and conveyor systems.
The barge was temporarily positioned on the river and tied off to the anchors in the location where the barge will be staged during removal operations. A safety line was attached to the barge and anchored to the shoreline as a precautionary measure in case the concrete anchoring points in the river were to fail. The safety line from the barge to the shoreline will be in place whenever the barge is deployed off shore.
Patches of ice began to form in the river surrounding the buoy markers, barge and surface above the proposed dredge area.
On Saturday, December 1, 2007, Site mobilization and setup continued. Dow’s contractors continued with the setup and installation of the water treatment, conveyor belt and dewatering systems. Crews continued setting up temporary shelters and roofing over the water treatment, dewatering and conveyor systems.
Dry test runs were performed on all the on land systems. The entire surface of the river was frozen over.
On Sunday, December 2, 2007, Site mobilization and setup continued. Dow’s contractors continued with the setup and installation of the water treatment, conveyor belt and dewatering systems. Crews completed the setup of the temporary shelters and roofing over the water treatment, dewatering and conveyor systems.
Heating systems were put into place throughout all of the shelters surrounding the water treatment, conveyor belt and dewatering systems.
The ice on the river was broken up with the use of a work boat and the barge was anchored in position out in the river next to the proposed dredge area. Crews connected the slurry pipeline from the barge to the dewatering system.
• Dow will setup turbidity monitoring stations up river and down river of the dredge area.
• Dow will begin to dredge and remove contaminated sediments within the proposed dredging area.
• Treatment and discharge of water generated from the impacted sediment dewatering operations.
• Transportation and disposal of the impacted sediment to Salzburg Road Landfill.
• Once the entire dredge, dewatering, water treatment, and sediment removal system has been completely installed, Dow will begin removal of contaminated sediments from the Saginaw River.
• Once the system is operational Dow will collect samples of the treated water discharged as specified in the modified work plan approved by the U.S. EPA.
• Dow will collect post removal confirmation samples throughout the dredged area.
• Dow will conduct site restoration activities as necessary.
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