DATE: August 23, 2016
TO: Board of Mayor and Aldermen
FROM: Eric Stuckey, City Administrator
Mark Hilty, Water Management Director
SUBJECT:
*Consideration of Resolution 2016-58 Authorizing City of Franklin Contract 2016-0265 with the State of Tennessee for the Clean Tennessee Energy Grant in the Amount of $250,000 for Components of the Proposed Water Reclamation Facility Upgrades
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Purpose
The purpose of this memorandum is to provide information to the Franklin Board of Mayor and Aldermen (BOMA) concerning Resolution 2016-58 authorizing the City of Franklin (COF) to enter into a contract with the State of Tennessee, COF Contract 2016-0265.
Background
The Clean Tennessee Energy Grant is a program administered through the Tennessee Department of Environment and Conservation (TDEC) that was initiated in 2011. The purpose of the Clean Tennessee Energy Grant Program is to help fund projects that result in a reduction of emissions and pollutants.
While the City’s grant application pertained solely to the biogas combined heat and power systems proposed with the biosolids facility, Franklin’s biosolids project was designed with sustainability, efficiency and pollution reduction as key focuses. As presented in the State’s press release for the grant awards “…applicants have proposed creative energy efficiency programs designed to decrease emissions and reduce expenses at the local level,” TDEC Commissioner Bob Martineau said. “We will continue to look for ways to promote environmental awareness and energy efficiency within state government and in Tennessee communities.”
A primary goal for staff and the design team was to develop a treatment train that would produce Class A biosolids. There are several drivers to achieve this standard and other benefits based on the design including:
1. Reducing dependency on landfilling solids to eliminate potential for increased tipping fees and risk associated with landfill capacity for biosolids
2. Generating a beneficial reuse product that can be used at residences, parks, commercial properties, agricultural facilities, etc.
3. Improve portfolio of disposal options
4. Reduced volume resulting in reduced solids handling equipment, capital expenses, and truck traffic to, from and within the site.
5. Source of renewable energy through the production of methane gas in the anaerobic digesters. The gas will be used to generate heat and electricity through a combined heat and power system helping to reduce dependency on natural gas and electricity.
All of these processes have been designed with sustainability and safety in mind. The key elements of the biosolids project include:
Thermal Hydrolysis Pretreatment (THP): THP is a new process at the facility. This process was selected due to the numerous benefits that it provides. The information below presents some of the key facts regarding THP.
1. THP is safely used at facilities throughout the world in both urban and rural areas. The CAMBI system, preselected for Franklin’s project, has been implemented at over 30 facilities worldwide.
2. The THP system is designed to significantly reduce solids volume which eliminates the construction of additional anaerobic digesters and other facilities to treat and manage solids.
3. Reduction of solids material results in less truck traffic, to, from and within the Water Reclamation Facility.
4. The process lyses the cells through heat and pressure using steam. There is no other chemical addition with the THP process
5. THP ultimately provides the ability to produce Class A biosolids material. Based on data from other facilities, including Washington DC Water’s Blue Plains Facility, staff expects that the City will produce an exceptional quality material.
6. The THP system pressures fall within the range recognized by the pressure vessel and piping industry as medium pressure rather than high pressure.
7. Control logic and instrumentation for the system is designed with multiple safety features that lock the pressurization process out in the event that overpressurization is occurring.
8. In the event that the controls fail, the pressure vessels are protected from rupturing because they are designed for pressures (180 psi) which are much higher than the actual pressures the vessels will ever experience, and the use of safety precautions such as rupture disks and pressure relief valves (which are activated at 165 psi) allows the vessels to depressurize without damage.
Anaerobic Digesters: The anaerobic digestion facilities will provide volatile solids reduction, which will further reduce the total solids to be disposed of and provide useful renewable energy by providing biogas that will be used as a fuel in the combined heat and power (CHP) system. Some key elements are provided below.
1. Anaerobic digesters are employed at over 230 municipal wastewater treatment plants in the United States, including the Metro Water Services Central WWTP, located in the Germantown community of Nashville and just minutes north of Downtown.
2. The digesters and all related gas handling equipment have been designed in strict compliance with applicable codes and industry standards. These technologies and practices have been used for decades in the wastewater industry.
3. Numerous safety measures are employed to ensure safe operation such as
a. Operating pressure of digesters is very low. Monitoring of pressure in the head space of each digester is performed so that over pressurization would cause heating to be stopped and immediate removal of a portion of the sludge to reduce pressure.
b. Use of pressure relief and vacuum relief valves on the digesters,
c. Monitoring of pressure in the pipelines, and
d. The use of flame arrestors
4. Methane is purposely produced in the anaerobic digesters. Anaerobic bacteria consume solids in the sludge and produce methane as a byproduct. This process has two benefits to plant operations: a reduction in the amount of solids to be handled (less truck traffic to and from the WRF) and the production of renewable energy.
5. Methane gas produced on-site will be treated and burned in a combined heat and power (CHP) engine which consumes the methane and releases carbon dioxide and heat. That heat will be captured and used to power a generator to produce renewable electricity on-site and to heat water into steam that is used to heat the sludge in the THP system.
6. If the CHP engine is out of service, the methane will all be consumed in the backup boilers. In the rare event that the boilers and engine are all down at the same time, then the methane will be burned in a flare.
Solar Dryer: The solar dryer system is proposed as a bid alternative. In addition to providing a more marketable end product, solids drying is proposed for the following reasons:
1. Solar drying is a proven technology and is being successfully used at numerous facilities throughout the world.
2. Infilco Degremont, Incorporated, the company pre-selected by the City of Franklin, has nearly 100 installations worldwide.
3. Solar drying was selected in contrast to thermal drying in large part to reduce costs and dependency on the purchase of natural gas for drying.
4. Drying of solids further reduces volumes which again reduces truck traffic to, from and within the property.
Financial Impact
The financial impact is a grant to the City of Franklin in the amount of $250,000.
Recommendation
Staff recommends the BOMA approve Resolution 2016-58 which authorizes the City of Franklin to enter into a contract (COF Contract 2016-0265) with the State of Tennessee for a grant in the amount of $250,000 through the Clean Tennessee Energy Grant program.