Six Very Bad Manholes
Jim Swain of CIP Construction Technologies Inc. was called in for a job in Fairbanks, Alaska a few weeks ago in mid-September. This was no ordinary job. The city of Fairbanks had 6 manholes in a row, all experiencing infiltration issues. This by itself is rather normal. Old deteriorated manholes leak. These however, had 432,000 gallons per day of fresh groundwater leaking into the structures accounting for 10% – 20% of the entire flow into the sewage treatment plant. Sounds like a lot and it is. Take the conservative estimate of $10 per 1,000 gallons to treat sewage in the U.S. This amounts to $4,320 per day for sewage treatment cost just for these six manholes. Yearly that translates to $1,576,800 in treatment cost for these structures. The exorbitant cost coupled with the fact that almost all of this flow was pristine Alaskan fresh ground water that now had to be treated as sewage meant something had to be done to permanently stop it.
To add to the difficulty, four of the six manholes were flat top structures. Additionally, back in April of 2021 another company from Texas had come in and injected large quantities of chemical grout to stop the infiltration but by August just four months later, they were all leaking profusely again.
There was also an artesian spring in the bottom of one of the six manholes that you could put your entire full length arm into. That single leak was contributing a whopping 188,000 gallons per day of clean Alaska spring water into the sewage system.
