A pilot study was established to evaluate the most effective, economical, and practical method to treat vactor solids (material extracted from roadway catchment basins) and street sweepings. Eleven piles of contaminated solid materials ranging in size from 1.25 to 5 cu yd (0.96 to 3.82 cu m) were treated using a matrix of conditions involving frequency of turning, fertilizer addition, peroxygen addition, and surfactant amendment. The treated piles, which were evaluated over 400 days, showed no difference in total petroleum hydrocarbon (TPH) and polycyclic aromatic hydrocarbon (PAH) levels relative to the control piles that were neither aerated nor fertilized.
The results of this study show that the most economical treatment of vactor solids can be achieved using intrinsic bioremediation; i.e., letting the contaminants of vactor solids and street sweepings biodegrade naturally. If sufficient land is available such a treatment scheme would require minimal operation and maintenance costs while providing an environmentally-acceptable fill product at the end of treatment.