Client:

Project:

Location:

Uhl completed a remedial investigation and report for a federal superfund landfill site underlain by carbonate bedrock. Uhl negotiated with the EPA for a no action in regard to groundwater pump-and-treat due to demonstrated non applicability for the site.

Principal Technical Elements:

• The installation and sampling of a monitoring well network in a complex carbonate rock area and the evaluation of groundwater flow conditions.
  
• The development of a regional water-level contour map and flow net for the site and area. This was a key technical input and assisted in focusing the risk assessment activity.
  
• The preparation of the remedial investigation report and technical input to the preparation of the feasibility study.
  
• Supplementary groundwater modelling in support of a request for no action in regard to groundwater pump-and-treat. The PRP committee requested Uhl's participation through issuance of a ROD for the site and Uhl conducted various activities in support of the PRP's preferred remedy.

Location:

Uhl designed, installed and operated a vacuum-enhanced recovery (VER) system at an industrial facility in Huntingdon, Pennsylvania.

The VER system was designed to remove and treat air and water containing elevated VOC concentrations from source areas in the soil/weathered bedrock and groundwater at the facility. The VER system was selected to address solvent contamination in soil and groundwater with minimal disturbance underneath the main facility building.

The VER system operation was a major element of the selected remedy for this facility that was implemented in accordance with a Remedial Investigation and Cleanup Plan prepared by Uhl. The RI and Cleanup Plan were approved by the Pennsylvania Department of Environmental Protection (PADEP) in fulfillment of requirements under the Land Recycling and Environmental Remediation Standards Act (Act 2) of 1995. Site-specific groundwater and soil standards were proposed and accepted for the facility based on the first point-of-use of the groundwater, where it discharged into a nearby stream.

The system was operated from April 1998 through December 2000. During this period, the VER system removed a total of 780 pounds (62 gallons) of TCE from the source areas at the facility. As expected, the system yielded its greatest benefits during the early months of operation, and over time the influent concentrations and daily removal rates reached an asymptotic state.

Water quality monitoring within the source area wells demonstrated that VOCs remained low in comparison to pre-remediation concentrations. With concurrence from PADEP, the system was permanently shut down after about three years of operation.

Principal Remedial System Components Included:

• A Decker Vacuum Technologies, Inc. 20 horsepower (hp) oil sealed liquid ring pump (LRP) rated for a nominal flow of 300 ACFM and a maximum vacuum of 29.5 inches of mercury (Hg).
• A QED EZ-Stacker 4-tray low profile air stripper designed for a 140 SCFM air flow and a maximum 10 gallons per minute (gpm) water influent rate
  
• Two 1600 lb. vapor-phase carbon canisters connected in series for the treatment of influent vapors. These were eliminated after 14 months of operation when the emissions became reduced.

Six recovery wells were connected into the system. The recovery wells were constructed with 4-inch diameter PVC well screen and casing to depths ranging from 16 to 28 feet. Each recovery well was equipped with a 1-inch diameter PVC drop pipe to which vacuum was applied, and groundwater and vapors were recovered by suction lift pumping.

Air extracted from the recovery wells by the LRP was combined with effluent air from the stripper. The total combined air stream was routed to the vapor-phase carbon canisters and was emitted outdoors through a vent on the building. Photographs of the VER system are attached.

Unisys Corporation, Eagan, Minnesota

Miscellaneous Projects at 3 Facilities

Location:

Warren, New Jersey; Park Ridge, New Jersey; and Joplin, Missouri

Uhl was under contract with Unisys from 1992 through 1997 for facilities in New Jersey and Missouri. Varied project activities ranged from further characterization to implementation and assessment of remediation. The Warren, New Jersey facility manufactured electronic components; the Park Ridge, New Jersey facility manufactured former Burroughs business machines; and the Joplin, Missouri facility manufactured hydraulic systems (former Vickers facility).

Principal Technical Elements:

• Hydraulic characterization during the startup of groundwater recovery systems at the Joplin, Missouri facility.
  
• Offsite groundwater characterization study at the Warren, New Jersey facility and groundwater flow and recharge assessment. This study identified another source for offsite VOC contamination in the area.
  
• Additional groundwater and product (LNAPL) characterization at the Park Ridge facility and evaluation of options for product recovery.

Somers, Westchester County, New York

Uhl & Associates, Inc. (Uhl) proposed, evaluated, and implemented the remedy selected for groundwater remediation at a shopping center contaminated with dry cleaning solvent (perchloroethylene (PCE)) in Somers, New York. The groundwater remediation systems were implemented as a part of the remedy approved by the New York State Department of Environmental Conservation (NYSDEC) after Uhl completed a Remedial Investigation and Feasibility Study (RI/FS) in accordance with the New York State regulations for cleanup of Inactive Hazardous Waste Sites.

The source area for the groundwater contaminants was relatively small (about a 20 by 20 foot area outside the back door where drums had been stored and apparently overflowed/leaked), yet caused an extensive groundwater plume due to the site hydrogeology and its unfortunate location right on a groundwater divide. Nearby residential and commercial wells completed in the bedrock aquifer were impacted in two different directions from the site.

Uhl coordinated and provided oversight of a quarterly monitoring program for the Interim Remedial Measure (IRM) that consisted of equipping 16 residences and commercial establishments with individual filter systems for about 8 years until other water supplies could be provided.

Based on our hydrogeologic analysis, Uhl designed a source area pump and treat system that captured water in both the glacial overburden water bearing zone and in the upper part of the bedrock aquifer. These recovery wells within the source area, captured shallow contaminated groundwater, reduced PCE concentrations; and protected against further leakage into the bedrock aquifer where concentrations were also lowered.

In the bedrock aquifer, Uhl directed the use of the existing shopping center water supply system comprised of two proximate bedrock production wells for remedial pumping purposes. For a one-year period, a containment-pumping test was conducted on these wells in order to determine optimal pumping rates for the maintenance of an inward hydraulic gradient over the impacted onsite areas. This containment-pumping test demonstrated that sustained pumping of either of the production wells at rates of 30 gpm or above effectively captured and contained most onsite groundwater; captured groundwater in the residential area to the east of the site, and limited the offsite migration of groundwater into other areas (refer to the attached March 2000 water-level contour map).

By the end of 2001, groundwater remedial pumping from the source area recovery wells and from the production well(s) was in operation for approximately 3.5 years. A substantial decline in PCE concentrations in both eastern and western onsite areas and in the residential area to the east was achieved during the pumping period and met groundwater remediation goals, established in conjunction with NYSDEC.

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