Summary Investigation and Findings of September 6-7 H2S Monitoring Alerts
On the evening of September 6th and into the following morning, and again in the late afternoon of September 7th, eight H2S alerts (registering above 30 ppb) were received and transmitted by the treatment plant's north and south fence monitors. The level of H2S peaked at 68 ppb and 70 ppb for two readings measured by the south fence meter between 5:30 a.m. and 6:00 a.m. on Saturday, September 7th.
The investigation check sheet shows the H2S levels recorded in various areas of the plant shortly after the south fence H2S alerts sent early Saturday morning. No unusually high levels of H2S were detected within the plant at that time. Throughout these events, Veolia management personnel maintained close communication with City of Richmond management staff.
A review of process operations of the treatment plant did not reveal any operational conditions or issues which could be linked to the H2S alerts. In fact, the treatment plant has been operating well and in compliance with discharge permit requirements.Chlorine in the form of sodium hypochlorite was being fed to the plant headworks for odor mitigation and ferric chloride was being fed to the digester for H2S control during the period.
The Bay Area Air Quality Management District Inspector assigned to Richmond was on site for several hours Monday morning (September 9th) in response to the H2S alerts reviewing data, documentation and plant operations. We were not notified of any issues prior to the District leaving the facility late in the morning.
On Saturday, in response to the increased frequency of H2S alerts, management scheduled Veolia staff to the site for continuous monitoring and observation between the hours of 6:00 p.m. and 3:00 a.m. for both Saturday and Sunday nights. Staff was on site, however, the alerts ceased after approximately 6:00 p.m. on Saturday. Late night coverage was discontinued after Sunday night but will be evaluated on a case-by-case basis and in consultation with City of Richmond staff going forward.
Weather conditions during the period were hot with calm winds, conditions that are known to historically favor H2S and odor development in both the collection system and treatment plant. These conditions will continue intermittently through the fall season, which is historically the most challenging season in regard to H2S and odors.
As Veolia's investigation did not discover any operational issues, the H2S measured last weekend could have originated from the collection system or other industrial and natural H2S sources in the area. Veolia will continue to work diligently to mitigate impacts from the treatment plant and will assist the City with its review of an H2S/odor reduction strategy.
Please remember the most effective means for us to address odor issues and concerns is for residents to place a phone call to our main number: (510) 412-2001.Odor complaints received via the phone hotline will be followed up 24 hours/day. Thank you.