Remedial activities performed by ENTACT included construction of a temporary diversion structure and stream channel bypass; installation of sediment filtration systems; mechanical dredging, solidification, staging, loading, and off-site disposal of 4,100 tons of PCE impacted soil, sediment, and plant process waste; restoration of the affected stream bed with clean imported fill; installation of rip rap and fiber mat erosion controls; and re-vegetation of disturbed wetlands and stream banks. 

After removal of impacted sediment, approximately 80 lineal ft of the stream bed subgrade was covered with 40 mil HDPE geomembrane to protect remediated areas from the influx of contaminated groundwater.  Rip rap was installed within the streambed to protect the toes of disturbed banks and prevent erosion.  The stream bed was backfilled to within 6 inches of original grade with common fill, then brought to final grade with a 6 inch lift of 6 mm gravel.

Wetlands Restoration Detail:

The restored areas were disked and seeded with switchgrass, flat pea and red top seed mix.  Seeded areas were mulched and protected with natural fiber erosion control matting. Coir fiber logs (12 inch diameter) were installed at the toe of disturbed stream banks and secured with wooden stakes. Plant plugs were then placed on the coir logs at 6 inch intervals. Plantings consisted of Swamp Milkweed, Sweet Flag, Sedges, Joe-Pie Weed, Blueflag Iris, Rushes, Cardinal Flower, Duck Potato and Bulrushes.

Tree and wetland shrub species located within the disturbed stream bank areas were replaced at 1:1 and 1:1.25 ratios respectively. Tree species included Sweet Gum, Green Ash, Black Willow and Purpleosier Willow.  Wetland shrubs included Red Osier Dogwood, Highbush Blueberry, Silky Dogwood and Smooth Adler. Two inches of mulch were placed around the bases of the new plantings. Tree trunks were staked and wrapped with translucent plastic tubes for protection.