Industrial Dry Cleaning Facility located in Western New York

Site Summary

Soil and ground water contamination by chlorinated solvents was discovered at a dry cleaning facility in a shopping center. The contamination had leached from the soil into underlying ground water and spread across the property. The contamination had spread to cover an area of approximately 10,000 square feet.

Geology

The geology of the property is interbedded sandy silt, silt, and clay. The contamination is in a shallow silty sand formation that is underlain by dense clay. A sand layer directly underlies the clay and is unaffected by the contamination in the upper sand.

Hydrogeology

The perched ground water at the property was within a fill layer, so the hydraulic permeability was expect to be variable. Slug testing results showed the hydraulic conductivity of the upper sand ranged from 1.1 to 3.9 ft/day. The direction of ground water flow was consistently toward a local surface stream.

Ground Water Contamination

The contaminants found at the site were mainly TCE and DCE with trace levels of vinyl chloride. This suite of contaminants indicated that there was natural degradation of the PCE to lesser halogenated compounds. The maximum concentrations prior to bioaugmentation were 220 µg/L of DCE, 9.2 µg/L of TCE and 31 µg/L of vinyl chloride.

The extent of ground water contamination covered approximately 10,000 square feet, but the application of bioaugmentation was focused on the high concentration area.

Remediation Design

CL-Out was introduced through one-inch diameter piezometers that were installed using a direct push sampler. The small diameter injection points made it possible to install injection points inside the cleaners without disrupting the facility operations. Three injection points were installed to cover the high concentration area, and additional injection was made into the soil excavations.

The first CL-Out inoculation in December 2005 was a dose of four drums to establish the CL-Out microbes in the treatment zone.

Results

Three months after the first injection the DCE concentration in the high concentration area decreased from 220 µg/L to 54 µg/L. The vinyl chloride concentration decreased from 31 to 11 µg/L. After seven months the concentrations of DCE and vinyl chloride decreased to 2.9 and below detection limits, respectively.

Due to the relatively low dissolved oxygen levels, Permeox Plus was added to boost or maintain the dissolved oxygen level during bioremediation. Permeox Plus was distributed between the excavation area and the injection wells. During the bioremediation, the dissolved oxygen levels and population of the CL-Out organisms were tracked to assess the viability of the organisms.

These monitoring results suggest that by supplementing the dissolved oxygen levels, the CL-Out population was maintained for an extended period. The extended CL-Out population made it possible to achieve a greater level of contaminant reduction.

The total CL-Out cost for this site was $6,000.