The City of Honolulu operates the Halekou Lift Station which pumps, on average, 35,000-50,000 gallons per day which, in turn, feeds into the Aikahi Wastewater Treatment Plant. The lift station is located in the Kaneohe neighborhood on the windward side of Oahu. The city is, of course, an extremely attractive tourist location, so when area residents began complaining of significant odors coming from the station, officials responded.
Wastewater engineers decided to treat the odor problem caused by hydrogen sulfide (H2S) gas, with a commonly used, but hazardous chemical, ferric chloride. They began the dosing regimen at 3.0 gallons a day and eventually increased that amount to 6.0 gallons per day. They measured the H2S levels at the force main discharge, using an Odalog hydrogen sulfide gas detection measurement and datalogging device. At a dosing level of 6.0 gallons per day, the average reading was 1.33 parts per million (ppm), with peaks in the 20-30 ppm range. Complaints from area residents continued.