Failed End Cap Weakened Pipes, Causing February Skokie Flood: Investigators

SKOKIE, IL — A failed pipe end cap is the likely cause of the February water main break that flooded Skokie streets, totalling cars and leaving thousands without water.

Engineering and scientific consulting firm Exponent presented its findings related to the investigation into the flood at the Nov. 17 Village Board Meeting. The village initiated the analysis immediately after the incident to determine the cause in order to prevent similar incidents from occurring.

According to the investigation team, the incident occurred on Feb. 14 at approximately 5:15 a.m. near the intersection of East Prairie Road and Emerson Street. According to residents who live in the flood-impacted area said the flood began the night of Feb. 13 and officials only discovered it in the morning.

Public Works Director Max Slankard said that it was clear that there was a communication issue during the incident between official channels and the community.

"In the future... we've talked about the utilization of a community liaison officer to serve as a resource to residents in the impacted area," Slankard said "Because I think we did have residents in the impacted area that felt like they were left alone."

Exponent's analysis indicated that the water loss occurred in a 36-inch transmission main after an end cap from a y-shaped pipe fitting manufactured in 1956 separated. Investigators believe that gradual deterioration of the cap and seal caused the separation and

Looking at flow data from the day of the incident, investigators saw a dramatic step change in the flow at around the 5 a.m. period on the 14th. Sean Dee, a chemical engineer working for Exponent, said that while there may have been indications of a leak before 5 a.m., the end cap had likely not been fully liberated until then.

Investigators did excavate the pipe involved in the flood, but were unable to locate the end cap. Testing done on the area where the end cap would have been held in place confirmed the presence of lead on the junction.

A review of Skokie's water records indicated that there were two other locations within the village's system that had similar pipe fittings to the one that failed in February. Crews excavated and replaced fittings at both locations over the summer.

Going forward, the village is preparing a Request for Qualifications for engineering and technical services to conduct an assessment of the transmission main system. The village will be specifically looking at pipes that are 20 inches in diameter or larger to guide future risk and rehabilitation planning.