Hydrogen Sulfide Ambient Air Monitoring Hummingbird Court, Marco Island, FL

1. Hydrogen Sulfide Ambient Air Monitoring Hummingbird Court, Marco Island, FL Presented at the City of Marco Island City Council Meeting October 29, 2007

2. Experimental Design • Four Stationary Hydrogen Sulfide Analyzers • Driveway Monitor • Air Discharge Monitor • House Monitor • Water Discharge Monitor • Weather Station • Wind speed, wind direction, temperature, humidity, rainfall and barometric pressure • Continuous Monitoring at 2-minute intervals

3. Monitor Placement Per Discussion with FL DOH and ATSDR • Monitors were placed based on discussions with ATSDR and FL DOH, wind forecasts, and professional judgment in the field • Driveway Monitor • Located at a more conservative distance of 38 feet from air discharge in swale across the street • Distance from air discharge to edge of home = 60 feet • Air Discharge Monitor • Located within site fencing at a more conservative distance between discharge and sidewalk ~ 10 feet from air discharge • House Monitor • Located at a more conservative distance of 48 feet from air discharge • Distance from air discharge to corner of house = 55 feet • Water Discharge Monitor • Located within site fencing at a distance approximating sidewalk exposure ~ 10 feet from water discharge

4. N Hummingbird CourtSite Layout and Monitor Locations E W S Treatment Unit Driveway H2S Monitors Air Discharge Water Discharge House

5. Monitoring Period

6. H2S Concentrations Detected at House MonitorHummingbird Court, Marco Island, FL Period “B” Post-Modification Period “A“ Pre-Modification ATSDR 1-Hour Average Criterion = 100 ppb ATSDR 1-Hour Average Criterion = 100 ppb

7. H2S Concentrations Detected at Driveway MonitorHummingbird Court, Marco Island, FL Period “A“ Pre-Modification Period “B” Post-Modification ATSDR 1-Hour Average Criterion = 100 ppb

8. H2S Concentrations Detected at Air DischargeHummingbird Court, Marco Island, FL Period “B” Post-Modification Period “A“ Pre-Modification ATSDR 1-Hour Average Criterion = 100 ppb

9. H2S Concentrations Detected at Water DischargeHummingbird Court, Marco Island, FL Period “B” Post-Modification Period “A“ Pre-Modification ATSDR 1-Hour Average Criterion = 100 ppb

10. Average H2S Concentrations (ppb) Detected at Hummingbird Court, Marco Island, FL

11. Average H2S Concentrations Detected at House Monitorby Wind Direction Pre- and Post-Treatment

12. Average H2S Concentrations Detected at Driveway Monitor by Wind Direction Pre- and Post-Treatment

13. Average H2S Concentrations Detected at Air Discharge Monitor by Wind Direction Pre- and Post-Treatment

14. Average H2S Concentrations Detected at Water Discharge Monitor by Wind Direction Pre- and Post-Treatment

15. Post-Treatment Ambient Air H2S Concentrations Do Not Exceed Any ATSDR/DOH Criteria

16. Conclusions • During Period B (post-treatment), the treatment process was effective at limiting ambient air H2S concentrations to levels below ATSDR/DOH criteria. • Maximum 10-minute peak concentration detected at any monitor was 125 ppb – well below the FL DOH/ATSDR 10,000 ppb criterion. • Maximum 1-hour average concentration at any monitor was 86 ppb – below the 100 ppb criterion. • Maximum 19-hour average concentration was 13.1 ppb – below the 24-hour criterion of 20 ppb. • H2S Concentrations detected during the initial monitoring period (Period A) exceeded FL DOH/ATSDR’s 1-hour criterion of 100 ppb and 24-hour criterion of 20 ppb. • Per FL DOH/ATSDR, system modifications were thereby warranted and initiated resulting in a marked improvement in H2S vapor control.

17. H2S Concentrations Detected at Source Monitor Amber Drive, Marco Island, FL Maximum 24-hour Average= 19.3 ppb ATSDR 1-Hour Average Criterion = 100 ppb