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 were completed by Dow’s contractor during the period from December 17, 2007 through January 9 2008:
Monday December 17th - Dow continued dredge operations concentrating on the removal of fine sediment over clay layer surfaces of the Eastern side of the dredge project area. Dow collected two confirmation samples in the Southwest corner of the dredge project area and one confirmation sample in the Northeast area. Contractors re-positioned dredge barge for additional dredge passes after receiving analytical results from previous sample locations.
Tuesday December 18th - Dow completed dredge operations and collected a post-removal sample. Contractors began the demobilization of equipment and supplies that would no longer be needed on site and began the decontamination of equipment.
Wednesday/Thursday December 19th & 20th – Dow received analytical results from post confirmation sampling and brought dredge barge to shore for load out of equipment, supplies and future dismantling. Decontamination procedures continued with an emphasis on large portions of the treatment infrastructure and associated frac tanks.
Friday December 21st – Contractors ‘flushed’ dredge/treatment system with river water at up to 1000 gallons per minute (GPM). Decontamination procedures continued along with the dismantling of the treatment system. Dow will transport treatment system and associated equipment to Dow facility for final decontamination.
December 22nd thru December 25th – No site activities.
December 26th thru December 28th, 2007 – Dow continued the dismantling and demobilization of the dredge treatment system and dredge barge.
December 29th thru January 1st – No site activities.
January 2nd – Dow completed the dismantling and demobilization of equipment and supplies and will leave one frac tank on site for final asphalt wash and rinse. One excavator remains on site for minor excavation (15’ by 15’)area under former booster pump location. Contractors completed the removal of all miscellaneous items from the Site.
January 3rd thru January 6th – No site activities.
January 7th – Dow utilized a high pressure power wash with a soap solution on the asphalt surface where the treatment system was located. Power wash water was collected in a sump and transferred to the site's remaining frac tank. A total of eight 25-gallon containers were filled with debris and staged onsite for later disposal at Dow’s Salzburg Road Landfill.
January 8th – Dow excavated 15’ x 15’ area under former booster pump location adjacent to asphalt containment pad. Dow collected a 3-point composite soil sample from the floor of excavation for analysis. Asphalt containment berms around storm sewer drains were removed to allow for storm water run-off and discharge. All miscellaneous small materials and supplies were removed from the site and final ‘house-keeping’ activities were performed including power sweeping the entire asphalt pad. Sediment debris containers collected from earlier operations were removed from site to Dow’s Salzburg Road Landfill. A Vac-truck was used to empty the remaining frac tank of decontamination water.
January 9th – Site trailers were removed from the site along with the generator, sump pump, and remaining frac tank. Electricians dismantled all temporary lighting and removed all associated cables and wiring. The Site was cleared of all remaining project debris and secured from public access.
• Dow has completed all removal requirements for this site. The only remaining actions for the site are removal of the temporary site fencing and park restoration later in the Spring of '08.
• Dow will corresponded with officials from the City of Saginaw to determine restoration requirements in the Spring of '08
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