Council Work Session Communication ______Biosolids Alternatives Evaluation
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Council Work Session Communication ________________________________________________________________________________ Biosolids Alternatives Evaluation Meeting Date: June 20, 2016 Primary Staff Contact: Lila Bradley Department: Public Works E-Mail: [email protected] Secondary Dept.: Public Works Secondary Staff Contact: Joe Whisler Approval: Ronald Chandler Estimated Time: 2 hours ____________________________________________________________________________________________ Objective Council will be presented with options on how to manage the City’s biosolids or sewer sludge. The presentation will include capital costs, maintenance costs, advantages and disadvantages of each option. Background The City’s wastewater treatment plant currently produces a Class B liquid bio-solids. Since 1993, our practice has been to apply Class B bio-solids onto fields in the Siletz Valley. This practice has afforded us relatively inexpensive bio-solids management. We began to experience the trend of fewer available fields in 2005-2006 and also had fewer contractors bidding on the dredging/hauling projects. The number of available fields continued to become increasingly limited, but in the past two years we have experienced a significant decline. Last year we applied 600,000 gallons out of the 2 million gallons produced per year. This year we have completed testing and found there are no fields available. We have been building an excess inventory in the holding lagoons and we need to remove sludge within the next few months. To address the immediate need, our consulting engineers from Kennedy/Jenks Consulting have been researching and negotiating prices from vendors to remove the bio-solids in the lagoons. Staff is also obtaining quotes and estimating costs for renting equipment. Classifications There are two methods used in the industry to manage solids: Aerobic Digestion and Anaerobic Digestion. Understanding the difference between the two methods is important to this discussion. Page 1 of 2 1. Aerobic digestion is a biological process that takes place in the presence of oxygen. With oxygen, bacteria present in the sludge (activated sludge) consume organic matter and converts it into carbon dioxide. We currently are using this process. 2. Anaerobic Digestion is a collection of processes by which microorganisms break down biodegradable material in the absence of oxygen. Converting our existing Aerobic digesters to anaerobic digesters was considered in the alternative evaluation. Also fundamental to the discussion is the type of sludge produced by the treatment process. Sludge can be treated to Class A or Class B. 1. Class A biosolids contain very very small levels of pathogens and can be land applied without restrictions. Class A bio-solids can be bagged and marketed to the public for application to lawns and gardens. Class A can only be achieved by thermal drying. 2. Class B biosolids have less stringent standards for treatment and contain small amounts of bacteria. Class B requirements ensure that pathogens in biosolids have been reduced to levels that protect public health and the environment and include certain restrictions for crop harvesting, grazing animals and public contact for all forms of Class B bio-solids. Alternatives For this work session, our consulting engineers from Kennedy/Jenks will be presenting the long term options to address our solids capacity and disposal. The options are: 1. Aerobic Class B 2. Aerobic Class A 3. Anaerobic Class B 4. Anaerobic Class A 5. Buy our own fields to land apply Class B 6. Privatizing dredging/dewatering/hauling Class B to landfill 7. Leasing dewatering equipment for near-term disposal Attachments: 2016 Biosolids Alternative Evaluation Report Page 2 of 2 421 SW 6th Ave, Suite 1000 Portland OR 97204 503-423-4000 FAX: 503-295-4901 City of Lincoln City WWTP Biosolids Alternatives Evaluation 6 May 2016 Prepared for City of Lincoln City 5000 SE Port Avenue Lincoln City, Oregon 97367 K/J Project No. 1576028 Table of Contents List of Tables ............................................................................................................................... ii List of Figures............................................................................................................................. iii List of Appendices ...................................................................................................................... iii List of Acronyms ......................................................................................................................... iv References ..................................................................................................................................v Section 1: Introduction and Problem Definition ........................................... 1 1.1 Authority and Purpose .......................................................................... 1 1.2 Existing WWTP Facility Overview ........................................................ 1 1.2.1 WWTP Liquids Process Overview ............................................. 1 1.2.2 WWTP Solids Process Overview .............................................. 3 1.3 WWTP Biosolids Challenges (Problem Definition) ................................ 3 1.4 Biosolids Storage, Beneficial Reuse, and Disposal .............................. 4 1.4.1 Federal and State regulations ................................................... 4 1.4.2 Class B Biosolids ...................................................................... 4 1.4.3 Class A Biosolids ...................................................................... 5 1.4.4 WWTP Class B Biosolids Evaluation ......................................... 5 1.5 City WWTP Flow and Load Projections ................................................ 5 Section 2: Alternatives Development ........................................................... 8 2.1 Introduction to Alternatives ................................................................... 8 2.2 Digestion ............................................................................................ 10 2.2.1 Aerobic Digestion .................................................................... 10 2.2.2 Anaerobic Digestion ................................................................ 11 2.2.3 Solids Dewatering (Class B Biosolids) ..................................... 20 2.3 Solids Drying (Class A Biosolids) ....................................................... 21 2.3.1 Belt Dryer ................................................................................ 22 2.3.2 Paddle Dryer ........................................................................... 22 2.4 Dewatering and Drying Equipment Pilot Testing................................. 23 Section 3: Alternatives Evaluation Methodology ........................................ 25 3.1 Triple Bottom Line Analysis ................................................................ 25 3.1.1 Triple Bottom Line Evaluation Procedure ................................ 26 3.2 Capital Cost Estimate Methodology.................................................... 26 3.2.1 20-Year Lifecycle Cost Estimating Methodology ...................... 27 3.3 Potential Outside Funding Sources .................................................... 27 3.3.1 Energy Trust of Oregon ........................................................... 27 3.3.2 Oregon Department of Energy ................................................ 28 3.3.3 The Bonneville Environmental Foundation .............................. 28 WWTP Biosolids Alternatives Evaluation, City of Lincoln City i y:\projects\2015proj\1576028.00_lincoln_city_biosolids\09_reports-memos\9.09_report\biosolids report\lc_tm_final_6may2016.doc Section 4: Alternatives Evaluation ............................................................. 29 4.1 Alternative 1 - Aerobic Digestion, Solids Dewatering and Class B Biosolids ......................................................................................... 29 4.2 Alternative 2 - Aerobic Digestion, Solids Dewatering, Solids Drying and Class A Biosolids ............................................................. 31 4.3 Alternative 3 - Anaerobic Digestion, Solids Dewatering and Class B Biosolids ............................................................................... 33 4.4 Alternative 4 - Anaerobic Digestion, Solids Dewatering, Solids Drying and Class A Biosolids ............................................................. 35 4.5 Alternatives Evaluation Summary ....................................................... 37 4.6 Alternatives Evaluation Findings ........................................................ 39 Section 5: Recommended Plan and Next Steps ......................................... 40 5.1 Discussion .......................................................................................... 40 5.2 Recommended Plan ........................................................................... 40 5.3 Next Steps ......................................................................................... 41 List of Tables Table 1-1. City WWTP Design Flow and Load Comparison ........................................................ 6 Table 1-2. Current and Design Secondary WAS Rates .............................................................. 6 Table 1-3. Dewatering Loading Characteristics .......................................................................... 7 Table 2-1. Summary of Dewatering and Drying Pilot Test Results ...........................................