RTG was contracted by the DePue Group to provide turnkey
services for the design and construction of an interim water treatment plant at
the DePue Site located in DePue, Illinois. In September of 1995, Horsehead
Industries, Inc., Mobil Oil Corporation, and Viacom International, Inc. (the
three of which together are referred to as the "DePue Group") entered
into an Interim Consent Order with the State of Illinois to conduct various
investigative and remedial activities, including the construction and operation
of an interim water treatment plant for the lowering of zinc and other metal
contaminant concentrations in groundwater contaminated due to leaching from
on-site waste piles.
In support of RTG’s proposal to the DePue Group for providing turnkey services, a treatability study was performed on the groundwater to be treated. Based on the results of the RTG treatability study, a design was proposed for the plant. RTG was successful with the proposal and was awarded the contract. It should be noted that in addition to providing design/construction services, RTG provided support to the DePue Group with multiple regulatory and permitting issues.
The Plant is designed to treat 25 to 125 gpm of water continuously, with operations personnel needed only during normal daytime working hours. The water treated is high in metals concentrations (3,500 ppm), with zinc being the metal present in the most significant concentration. Primary unit operations in the facility include (see attached process flow diagram):
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Lime precipitation process with sludge recycle (high density sludge recycle);
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Clarification;
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Effluent neutralization;
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Sludge storage and dewatering; and
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Sludge stabilization.
The process produces a sludge underflow from the clarifier/thickener. The thickened sludge is dewatered to approximately 25 to 30% solids by weight. Dewatered sludge is blended with an additive (kiln dust) to ensure that the sludge passes TCLP.
RTG managed construction of the facility and completed start-up
operations. In addition to the base treatment facility, RTG was responsible for
construction of a lift station and interceptor system to collect the
contaminated gro
undwater and transfer it to the treatment facility.