F-7: Commissioning of Sewage Plant

 Statement of the Case: A consulting engineering company was awarded the contract for

designing, preparing the specifications, and providing “field inspection services” (monitoring the

construction) of a sewage treatment plant being built for a small municipality. The construction

proceeded routinely to completion. The consulting company employed Engineer A, an environmental engineer experienced in wastewater treatment, to assist in the field inspection.

During the final commissioning of the plant, Engineer A observed that the biochemical oxygen

demand (BOD) of the effluent was frequently above the acceptable limit.

Engineer A contacted the design office at his engineering company, and after reviewing the case

with an environmental consultant, he soon realized that the plant had been designed for average

flows, but several food-processing industries in the municipality occasionally fed “slugs” of raw

sewage to the plant. The biochemical oxygen demand would increase rapidly when one of these

slugs arrived and would remain above the regulated limit for a few days, before moving back

down below the limit.

Engineer A concluded that, on days when these slugs were being

processed, the plant would not meet the effluent quality standards. The specifications had been

set by the engineering company’s design office, which had used the average sewage flow

estimates. He faced a serious decision, and identified three courses of action. Should he

 disclose this deficiency to the municipality (the client), thus implicating the engineering

company (his employer) as responsible for the inadequate design, or

 selectively sample the plant effluent between slug discharges, thus falsifying the true nature

of the problem, or

 provide “average” readings in his commissioning report, which might be a defensible

compromise?

Question: What should Engineer A do, in this situation?

Outcome: Engineer A concluded that he must act as a faithful agent of the client, even if it

created problems for the engineering company employing him. He met with engineers from the

municipality and explained that the sewage plant was unlikely to pass the commissioning tests

because of the “slug” discharge problem. The municipality was unaware of this problem and

immediately requested an explanation from the food-processing industries. After a lengthy

negotiation, the industries agreed to make structural changes to piping that would make the

sewage flow more constant and to build an “equalization” basin upstream from the sewage plant,

where the slug flows would blend with other flows, thus providing a much more constant sewage

flow, which the plant could process. The municipality contributed the land, the engineering

company agreed to design the equalization basin as a public service, and the industries agreed to

an increased mill rate to cover construction and maintenance costs for the basin.

Authors’ Comments: Truth was essential. The truth would have become obvious, eventually,

and a lawsuit would have followed. Professionals always prefer solutions to lawsuits.