Site Remediation
Avesta Sheffield
Baltimore, Maryland

This project consisted of remediating a stainless steel recycling facility. The purpose of the project was to eliminate the off-site migration of low pH groundwater contaminated with oils and heavy metals. An existing storage pond holding 8,600 cy of lime sludge was stabilized, spread and capped.

A 95,000 sf groundwater cutoff wall was installed on the down gradient perimeter of the site. The wall was 3,400 feet long with depths ranging to 43 feet deep. The vibrating beam method was used to install the wall, having a permeability of 1 x 10^-8 cm/sec or less.

Approximately 15 feet upgradient from the cutoff wall, a series of three collection trenches were installed using the Bio-Polymer slurry trench technique for excavation. The trenches totaled 70,000 sf, with depths ranging to 40 feet deep. Collection sumps and conveyance piping were installed in the trenches, and then they were backfilled with gravel. A groundwater recovery system was also installed to move water from the collection sumps to the on-site water treatment unit.

The 8,600 cy of lime sludge was stabilized with backhoes by adding approximately 10% Portland Type I cement. The lime sludge was excavated from the storage pond, spread over the adjacent south slab yard area and mixed with cement. The pond was then backfilled and the south slab yard was capped and revegetated.

This project was completed on schedule, and through the implementation of several of Geo-Con's value engineering suggestions, it was also completed at 10% less than the original contract value.

• Start: 8/12/96
• Completion: 12/27/96