STAFF REPORT

Operations Committee, December 6, 2007

Odor Identification and Abatement Study (EN08-059)
Consideration of Conducting an Odor Identification and Abatement Study at the South Cary Water Reclamation Facility (SCWRF).
Speaker:  Mr. Tim Bailey
 

From:  Tim Bailey, PE, Director of Engineering

Prepared by:  Steve Brown, PE, Associate Director of Engineering

Approved by:  William B. Coleman, Jr., Town Manager

Approved by:  Benjamin T. Shivar, Assistant Town Manager

Background:  The Town has received an increasing number of complaints of odors in neighborhoods bordering the SCWRF over the past several months.  Public Works and Utilities staff has worked diligently to identify and resolve odor sources from the plant and nearby collection system, including:

• Frequent neighborhood visits including nights and weekends for identification and measurement of odors;
• Continually monitoring and optimizing the effectiveness of the existing headworks odor control system completed in late 2006;
• Frequently changing the odor scrubber’s carbon media;
• Installed an additional odor treatment system at the plant headworks;
• Continually feeding and adjusting odor control chemicals in the collection system;
• Frequently flushing the nearby wastewater collection system with reclaimed water, including use of a permanent flushing connection, to reduce the odor potential of the wastewater;
• Sealed and at some locations added special odor removal filters on manholes;
• Smoke tested the plant headworks and manholes in the neighborhood to identify leaks of odorous air; and,
• Rescheduled biosolids processing activities to late night and early morning to reduce their odor potential.

Despite these efforts, off-site odors are still detectable at certain times of day and under certain weather conditions.  Therefore, staff recommends that a consultant with specialized training and equipment be hired to:

• Positively identify and evaluate all odor sources on the plant site and in the collection system near the plant;
• Conduct field measurements of odor intensity and generation at each odor source to quantify their generation rates;
• Prepare a meteorological and topographical model to predict off-site odor potential; and,
• Recommend abatement measures that will prevent odors originating in the Town’s wastewater collection and treatment systems in this area from being detected off the plant site.

Staff requests direction from Council on whether to proceed with this study at this time.  A final report will be prepared that may recommend operational and/or capital improvements at the SCWRF to prevent the occurrence of off-site odors.  Staff will provide a report to Council of recommended improvements after this report is completed.  The selected consultant may be tasked with design and construction administration for the recommended improvements to facilitate timely implementation.

Fiscal Impact:  Funds are currently available in project SW1112 for these professional services.  Construction funding is available in the FY2008 CIB and included in proposed FY2009 CIP projects.

Staff Recommendation:  Staff recommends proceeding with the odor identification and abatement study.