Removal and Disposal of Waste From Underground Structures in the Con Edison System

Borreggine, Gerald

Removal and Disposal of Waste From Underground Structures in the Con Edison System

2002

New York Institute of Technology

Hazardous wastes
Refuse and refuse diaposal
Refuse and refuse disposal
Sewage disposal

English

PDF

Thesis (M.S.)--New York Institute of Technology

School of Engineering and Computing Sciences

Department of Environmental Technology

Stanley M. Greenwald, P.E.

The Consolidated Edison Company of New York, Inc. is engaged in the generation and distribution of electricity, natural gas and steam in New York City and parts of Westchester County. In order to distribute electricity efficiently it has more than 275,000 underground structures in its distribution system. 1 These structures consist of manholes, service boxes and transformer vaults. Utility workers must enter these structures to maintain electrical equipment and electric cables and wires. Liquid and solid debris can accumulate in these underground structures and Con Edison must clean them out so those workers can safely work there.
Specialized trucks known as flush trucks were used to spray clean water into manholes and then pump the water out into a holding tank on the truck. The flush truck could then go on to the next structure and repeat this function except now the water contained debris from the previous job. The flush truck was introducing contaminated water into a manhole that may not have had those contaminants. This contaminated water was brought to one of five flush truck facilities located in New York City. When a flush truck arrived at one of the flush truck facilities, water was decanted into a sedimentation basin to allow solids to settle. The water was then discharged into the New York City sewer system. The solids were unloaded and allowed to dry. They were then sent to an off site disposal facility.
In 1992, samples of the solid debris indicated that some material exceeded the hazardous waste limit for lead. Con Edison realized that it was transporting hazardous waste without the proper permits. The Company notified the New York State Department of Environmental Conservation and entered into an Administrative Order of Consent. The Company developed a plan to remove this hazardous waste from underground structures and to properly dispose of it.
This report discusses the waste found in the underground structures in the Bronx and Westchester County and the alternatives considered in its removal and disposal. A newer type of flush truck called a Vactor truck is now used because this truck never mixes clean and contaminated water. Vactor trucks have a large vacuum, which can remove dry debris from a manhole so less water is necessary to clean a structure. During the last year, 582 tons of solids and 508,000 gallons of liquid were removed from underground structures in the Bronx and Westchester. The applicable laws and regulations are discussed, as are the contaminants of concern. This paper discusses alternative methods considered to remove the waste, the method chosen to remove and dispose the waste, the rehabilitation of the Hellgate flush truck facility in the Bronx, and the continuing problem in disposing the liquids. Vactor trucks are used to vacuum solid debris in the structures and then clean water is used to flush the structure. This water is now vacuumed into the truck and transported to Hellgate where it is later disposed of.