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START continued to screen the areas beneath excavation to determine "clean" areas with lead concentrations below 1,000 ppm. START collected samples from approximately 20% of these locations and shipped the samples for laboratory analysis and confirmation. START continued to draft maps that contain Site photographs of the excavation areas depicting XRF data at the sample locations.
Under the direction of the OSC, ERRS completed excavation activities on the Site. Additional subsurface lead-contaminated soils, up to 61,056 ppm, were discovered. The extent of this contamination is unknown. The contamination appears to extend into the hillside, in a direction away from the creek. ERRS covered all exposed contaminated areas with two feet of fill and graded the hillside. The fill that was utilized for cover was taken from the property; no fill material had to be purchased. Analytical data verified the absence of contamination in the fill material.
T&D operations were completed on March 10, 2010. A total of 235 trucks, carrying a payload of approximately 5,563 tons, transported the lead-conatminated soils to a landfill in Detroit, Michigan.
START continued to conduct air monitoring with DataRAM 4000's along the southern, western, and eastern areas of the Site during T&D and excavation operations. The maximum concentration of particulates that migrated from the Site during this operational period was 27.3 ug/m3.
START continued to conduct personal air monitoring for particulates in the hot zones. The instrument was rotated among the operators in the excavator and articulate dump in the excavation area and the laborers and operator in the stockpile area. The maximum concentration of particulates in the hot zone during this operational period was 67 ug/m3. No respiratory protection was necessary during this operational period.
The OSC has allocated an additional $22,000 to START for air monitoring costs and to subcontract a surveyor. START awarded a subcontract for completion of the survey and a map depicting Site elevations and topography.
ERRS completed backfilling the excavated areas of the Site and graded the Site to allow appropriate drainage of rain water into Beaver Creek. ERRS hydroseeded the Site on March 27, 2010. ERRS decontaminated and demobilized all equipment and personnel from the Site by April 2, 2010.
Interested parties may view added recent pictures in the Images section of the website: www.epaosc.org/twincities.
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