PROJECT OVERVIEW 4

Lead Contaminated Soil Remediation
Conducted for the Star Plating Corporation
New Bedford, MA

Introduction

Atlantic Environmental Technologies, Inc (AET) was the environmental engineer and Licensed Site Professional (LSP) for the Star Plating facility in New Bedford, MA. The contamination at these sites from plating operations is assumed to have occurred over a long period of time and is not considered to be the result of a single "release" event. The MA DEP was notified of reportable concentrations (RCs) for the disposal site in 1995.

Recent investigations have been conducted at this site since 1995. During this period, it was determined that there was lead contaminated soil at the site and groundwater was contaminated with elevated concentrations of cadmium, nickel and zinc. Soils heavily contaminated with lead were determined to be confined to an area 20 feet x 20 feet x 6 feet deep at 19 Coffin Avenue. Dissolved metals in groundwater were found to exceed either Method 1 Cleanup Standards, Upper Concentration Limits (UCLs) or both at both the 19 and 41 Coffin Avenue Properties.

Remedial Design and Implementation

AET determined that the volume of lead contaminated soil that needed to be remediated at the site was between 75 and 100 yards (112 to 150 tons). Because Star Plating did not want to implement an Activity and Use Limitation (AUL) on the property, the most stringent Method 1 soil standards needed to be achieved (S-1 in Massachusetts) at the site. Because lead is an involatile substance and because Star Plating did not want to implement an AUL at the site, AET determined that excavation and removal of the contaminated soil was the preferred option for this situation.

A review of groundwater monitoring data in 2000 indicated that there remained GW-3 Method 1 groundwater exceedances in groundwater. The contaminants of concern were metals and therefore not volatile. AET evaluated the contamination with proper groundwater concentration averaging and Method 2 Risk Assessment techniques and determined that groundwater remediation at this site would not be necessary. Method 2 Risk Assessment revealed that there was a condition of No Significant Risk in regard to the existing groundwater contamination profile at the site.

Lead Contaminated Soil Excavation

AET supervised the excavation of 55 cubic yards of Lead Contaminated Soil on May 22, 2001. AET classified the soils encountered as urban fill that contained brick, asphalt and slag fragments. Soil was excavated to a depth of 6 ½ feet. Closure samples were collected and analyzed from the sidewalls and bottom of the excavation. These samples were submitted for analysis of Total Lead. Analysis did not detect levels of Total Lead in any of the confirmatory samples exceeding the laboratory reporting limit (i.e. all results were reported as ND or "Non-Detect"). Therefore, closure sampling indicated that the excavation activity was successful in removing all of the lead-contaminated soil that was targeted.

Soil Stabilization and Disposal

Lead concentrations in the resulting soil pile exceeded Massachusetts Upper Concentration Limits and would have required disposal at a RCRA facility such as Model City, NY. AET recommended to Star Plating that Soil Stabilization be conducted on the soil pile to reduce the cost of disposal. Soil Stabilization is the process of reducing leaching potential of contaminated soil so as to allow for disposal at a less stringent facility. In this instance, portland cement was utilized to facilitate the soil stabilization.

Stabilization of the soil pile was conducted on May 23, 2001. Prior to stabilization procedures, the soil pile was screened to remove all material with a grain size exceeding ¾ inch. Materials larger than ¾ " was put back into the empty excavation. The screened material was then fed into a hopper for mixture with portland cement. The portland cement mixture would chemically immobilize the lead from leaching from the soil in the future. Once mixed, the soil/portland cement mixture left the hopper on a conveyor belt where it as removed by a front-end loader for stockpiling. After a one-week curing period, soil samples were collected from the pile for TCLP (leaching) potential analyses. The result was less than 0.25 mg/kg, therefore negating the need for RCRA disposal.

Soil Disposal

AET prepared the required transportation and disposal documentation and on November 1, 2000, 82.52 tons of stabilized, lead contaminated soil was removed from the site and transported as non-hazardous material to the Waste Management-Crossroads facility in Norridgewock, ME. Crossroads is a landfill disposal facility with far lower costs than those associated with RCRA regulated hazardous waste disposal.

Conclusions and Results of AET Recommendations

Soil contaminant concentrations were reduced to acceptable levels in accordance with MA DEP, whereby Method 1 / S-1 Cleanup Standards were achieved. Risk characterization indicated that groundwater remediation was not necessary. With the completion of the soil excavation, stabilization and disposal work, a permanent solution at the site had been achieved. A Class A-2 RAO was submitted to MA DEP on July 30, 2001. Star Plating achieved substantial financial savings by avoiding the transportation of soils contaminated heavily with lead to a RCRA disposal facility.