Once Upon a Time in Construction: When Promises Fall Apart

Our client was distraught and blurted out “ they said it would work” and now we have to demolish it. How did this happen?
During the mid-90’s it was feared by the EPA that landfills would soon be at capacity to accept sewage sluge and the EPA had recently banned ocean dumping off the New Jersey coast. EPA proposed a solution and funded demonstrations of how to overcome this issue for waste water treatment plants in the densely populated North East. The recommended solution was to make fertilizer pellets from the sewage sludge in a newly envisioned process. A number of plants were designed and built to perform this alchemy. One such was built by our client.

Investigating the engineering studies and design for the plant we quickly identified the source of the failure. As is customary pilot studies of the sludge to pellet process were conducted and results properly reported but not analyzed for suitability in practice. It is important to note that sewage sludge is somewhat unique to each municipality due to the mix of industrial and residential/commercial contributors. This makes the pilot testing much more important for predicting the actual results of processing. It was revealed that during the pilot plant testing phase, problems resulted in the pellet’s mechanical properties for durability and breakage. In the actual operation of the completed facility, the pellets that were made quickly turned to dust, rendering them useless in any application.

How then did this happen only to be discovered after a $ 30 million facility was built and operated. The overall process was developed and researched by the EPA and guidelines established for the production and use of the finished pellets. The critical failure occurred in the pilot plant testing of the sludge. The testing lab determined that in order to make durable pellets a small amount of water was required to be added to the mix prior to the pellet forming stage. However, in order to eliminate virus and vector infections the bake temperature and water content of the forming stage had to be within narrow limits and precluded the addition of water to obtain the desired mechanical properties. The engineering evaluation of the studies and there application to the actual
overall process requirements did not acknowledge the conflicts inherent in the need to eliminate vectors and the need to instill the needed mechanical properties. No satisfactory admission or acknowledge of responsibility was ever provided and the ultimate conclusion of a long litigation was that the liability rested with the environmental engineers who designed the facility and the operator demolished a completed facility selling the equipment for scrap value.

The moral of the story is that engineers must not only perform all the required steps in design process but anticipate problems and see the results with the eyes of an engineer to protect the client’s interest. The EPA had projected that many of these plants would be built and operated but similar to the Trash-to Steam failures only a few in unique situations were constructed
and could be successfully operated.