This report presents cost and performance data for the application of on-site incineration at the MOTCO Superfund site in Texas City, Texas. Incineration began in May 1990 but was halted in December 1991 by a contractor dispute. Contaminants of concern at the site were PCBs, styrene tars, volatile organic compounds (VOCs), and metals.
The MOTCO site was established in 1959 for the recycling of styrene tars. The recycling was discontinued in 1961 due to damage by Hurricane Carla. From 1961 to 1968, on-site pits that held styrene tars were used for the disposal of chemical wastes from local industries. In March 1985, a Record of Decision (ROD) that required source control was signed, and in September 1989, a ROD that addressed off-site migration of contaminants was signed. This report addresses the incineration specified in the first ROD, unless otherwise stated.
The remedy selected for the first Operable Unit (OU-1) was off-site treatment and disposal of contaminated material; however, the ROD specified that on-site incineration was a viable alternative to be evaluated during the design phase. A later Consent Decree required on-site incineration and set incinerator requirements including a destruction and removal efficiency (DRE) of 99.99% for each principal organic hazardous constituent (POHC) and 99.9999% for polychlorinated biphenyls (PCBs).
The site operated two incineration systems. The first system was called the Hybrid Thermal Treatment System® 2 (HTTS®-2), and the second system was referred to as HTTS-3. The HTTS-2 consisted of a rotary kiln, a secondary combustion chamber (SCC), and a gas cleaning system. This incineration system processed solids, sludges, tars, aqueous wastes, and organic liquids. The HTTS-3 consisted of a combustion chamber and gas cleaning system identical to the SCC and gas cleaning system of the HTTS-2. The HTTS-3 processed only aqueous wastes and organic liquids.
In the rotary kiln, organic compounds from the contaminated material were volatilized and destroyed. The exhaust gases were channeled to the SCC. The SCC provided further combustion of organics in the off-gases, which were then water quenched. Waste oils were used as fuel in the kiln and SCC of the HTTS-2 and in the combustion chamber of the HTTS-3.
The gas cleaning systems for both incineration systems consisted of a quench system, a gas conditioner, a wet scrubber, and a vane separator. The quench system and gas conditioner removed particulate and acid gas. Caustic solution was sprayed into the gas stream in the wet scrubber for particulate matter and acid gas removal, and the solution was then removed from the gas stream by the vane separator.
In December 1991, the HTTS-3 had passed the trial burn and was performing under interim operating conditions, and the HTTS-2 was in the process of conducting a trial burn when the contractors stopped incineration and filed a lawsuit against the responsible party (RP) for breach of contract. Due to the dispute and several technical problems (including slagging), on-site incineration did not resume.
In January 1993, an Explanation of Significant Differences (ESD) specified off-site incineration of the remaining sludges, tars and organic liquid. The remaining soil was to be capped on site.
The cost incurred during the on-site incineration was approximately $76 million consisting of $20 million in capital costs and $56 million in operating costs.
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