Mendenhall Wastewater Treatment Plant Energy Audit

Transcription

1 Mendenhall Wastewater Treatment Plant Energy Audit Final Report August 18, 2009 Mendenhall Wastewater Treatment Plant City and Borough of Juneau Prepared for: City and Borough of Juneau Contract No. RFP E Prepared by: Alaska Energy Engineering LLC Amalga Harbor Road Tel/Fax: Juneau, Alaska

2 This page intentionally left blank

3 Table of Contents Table of Contents 1 Project Team 2 Abbreviations 2 Section 1: Executive Summary 3 Plant 3 Energy Use Summary 3 Energy Conservation Opportunities 3 Facility Guidelines 7 Summary 9 Section 2: Introduction 11 Plant 11 Energy Use Summary 11 Methodology 13 Section 3: Buildings 17 SBR Building 17 Disinfection Building 25 Belt Filter Press Building 27 ABF Plant 28 Jet Truck Garage 29 Lube Oil Building 30 Collections Building 31 Section 4: Wastewater Treatment Process 33 Influent Pump Station 33 Sequencing Batch reactors 33 UV Treatment 34 Sludge Treatment 34 Motors 35 Section 5: Energy Conservation Opportunities 37 Appendix A: Appendix B: Appendix C: Energy Use Data Energy Analysis Calculations Life Cycle Cost Analysis Calculations City and Borough of Juneau 1 Mendenhall WWTP Energy Audit

4 Project Team Energy Engineering Jim Rehfeldt, P.E., Mechanical Engineer Alaska Energy Engineering LLC Amalga Harbor Road Juneau, Alaska Civil Engineering Jim Dorn, P.E., Civil Engineer Carson Dorn Inc. 712 West 12th Street Juneau, Alaska Abbreviations AEL&P Alaska Electric Light & Power Co. HWP Heating water pump ABF Aerobic Bio-Filter Inc. Incandescent AHU Air handling unit JDWWTP Juneau Douglas WWTP CBJ City and Borough of Juneau kw Kilowatt CFL Compact fluorescent lamp kwh Kilowatt-hour CGFP Cooling glycol feed pump LCB Last Chance Basin CP Circulating pump MCC Motor control center ECO Energy conservation opportunity MWWTP Mendenhall WWTP EF Exhaust fan NPW Non-potable Water FOP Fuel oil pump SBR Sequencing Batch Reactor HGFP Heating glycol feed pump SF Supply fan HP Horsepower T8 or T12 Fluorescent lamps HPS High pressure sodium UV Ultraviolet HWP Heating water pump VFD Variable frequency drive HVAC Heating, ventilating, air-conditioning WWTP Wastewater Treatment Plant GPM Gallons per minute City and Borough of Juneau 2 Mendenhall WWTP Energy Audit

5 Section 1 Executive Summary This report presents the findings of an energy audit of the City and Borough of Juneau Mendenhall Wastewater Treatment Plant (MWWTP). The purpose of the energy audit is to identify energy conservation opportunities (ECOs) and determine if investments in energy efficiency will provide a life cycle savings. The findings were gathered through on-site observations, review of construction documents, and interviews with operations and maintenance personnel. The energy audit was performed by Jim Rehfeldt, P.E. of Alaska Energy Engineering LLC with technical assistance by Jim Dorn, P.E. of Carson Dorn, Inc. PLANT DESCRIPTION The Mendenhall Wastewater Treatment Facility processed 840 million gallons of influent in Wastewater flows through the following process: Influent Pump Station: The influent flows into the plant, solids are ground and a sieve removes rags. The flow settles in the influent well and is lifted into tea cup strainers that remove grit. The grit falls into a grit clarifier where it is removed. Sequencing Batch Reactors (SBRs): From the influent pump station, the water is distributed to one of eight SBRs where it is treated using aeration blowers and jet circulation pumps. UV Treatment: When an SBR completes a reaction cycle, the water is decanted and disinfected by UV treatment prior to discharge to the Mendenhall River. Sludge Process: Sludge from the SBRs is stored in the sludge storage tank. The sludge is dewatered in a belt filter press and trucked to the JDWWTP for incineration. ENERGY USE SUMMARY The plant consumes 3,000,000 kwh of electricity per year at an average electric demand of 497 kw per month. Electricity costs are $240,000 per year at an effective cost (sum of energy and demand charges) of 8.0 per kwh. The plant consumes 113,000 gallons of fuel oil per year at a current cost of $215,000 per year. ENERGY CONSERVATION OPPORTUNITIES The energy audit revealed energy conservation opportunities associated with the buildings and the wastewater process. The energy performance of each ECO is evaluated based on the operating parameters of the water system and facilities. The economics are evaluated by a life cycle cost analysis. City and Borough of Juneau 3 Mendenhall WWTP Energy Audit

6 Behavioral or Operational Energy Conservation Opportunities Top priority should be given to the following behavioral or operational ECOs. Many require minimal investment and/or offer immediate savings. The savings from these ECOs is variable and depends upon the level of implementation, which cannot be readily predicted. The ECOs are listed from highest to lowest priority. ECO-1: Reduce Blower Room Temperature ECO-2: Reduce Heating Setpoints ECO-3: Turn Off Unneeded Lighting ECO-4: Reduce Unoccupied Room Temperatures ECO-5: Review Sludge Treatment Process ECO-6: Optimize SBR Blower Operation ECO-7: Discontinue Lube Oil Building Heat ECO-8: Install Interlocks on Overhead Door with Heaters ECO-9: Install SBR Building Main Entrance Heater Thermostat ECO-10: Convert HVAC Systems to DDC Controls ECO-11: Insulate Heating Piping ECO-12: Replace ABF Boiler Operating Thermostat ECO-13: Adjust Disinfection Building Backdraft Dampers ECO-14: Seal ABF Plant Exhaust Louvers and Ducts ECO-15: Evaluate Feasibility of Eliminating the ABF Plant Boiler ECO-16: Turn Off SBR Building Water Cooler ECO-17: Reduce SBR Building Air Compressor Pressure ECO-18: Insulate Collections Building Hot Water Tanks ECO-19: Reduce SBR Building Hot Water Temperature ECO-20: Install Lighting Occupancy Sensor Control ECO-21: Adjust and Monitor Exterior Lighting Photocells ECO-22: Turn Off Lab Dryer and Furnace ECO-23: Turn Off Idle Computers ECO-24: Insulate SBR Building Emergency Generator Ductwork ECO-25: Install Water-Conserving Aerators and Shower Heads ECO-26: Install Automatic Controls for EF-105A/B/C ECO-27: Test, Adjust, and Balance HVAC Systems ECO-28: Retrocommission SBR Building HVAC Systems ECO-29: Weather-strip Exterior Doors City and Borough of Juneau 4 Mendenhall WWTP Energy Audit

7 High and Medium Priority Energy Conservation Opportunities Table 1-1 is a list of each recommended ECO that will require an investment of funds. The table lists the construction, maintenance, and energy costs of each ECO over a 25-year period. The ECOs are listed from highest to lowest priority. Table 1-1: Life Cycle Cost Analysis Summary Energy Conservation Opportunity Construction Maintenance Energy Total LCC High Priority ECOs ECO-30: Turn Off SBR Lag Boiler $200 $9,300 ($155,100) ($145,600) ECO-31: Turn Off Boilers in Summer $200 $13,900 ($97,000) ($82,900) ECO-32: Reduce UV Output to Two Banks $1,000 ($67,600) ($154,700) ($221,300) ECO-33: Repair AHU-101/102 Heat Recovery $2,500 $2,300 ($521,600) ($516,800) ECO-34: Repair AHU-103/104 Heat Recovery $2,500 $2,300 ($521,600) ($516,800) ECO-35: Install ABF Boiler Rm Heat Recovery $2,500 $1,200 ($57,300) ($53,600) ECO-36: Replace Clothes Washer $800 $0 ($6,800) ($6,000) ECO-37: Install AHU-105 Heat Recovery $51,500 $2,300 ($309,800) ($256,000) ECO-38: Install Auto Valves on Unit Heaters $11,100 $0 ($69,300) ($58,200) ECO-39: Replace HVAC Motors $13,100 $0 ($39,400) ($26,300) Medium Priority ECOs ECO-40: Convert to VFD Hydronic Pumping $29,100 ($4,600) ($60,800) ($36,300) ECO-41: Insulate Collections Building Walls $42,400 $0 ($84,000) ($41,600) ECO-42: Install MCC Room Heat Recovery $26,000 $2,300 ($49,700) ($21,400) ECO-43: Replace Collections Bldg Windows $7,000 $0 ($11,700) ($4,700) ECO-44: Replace Process Motors $10,000 $0 ($15,800) ($5,800) ECO-45: Insulate Collections Bldg Roof $23,800 $0 ($34,700) ($10,900) ECO-46: Upgrade SBR Building Lighting $1,100 $0 ($1,600) ($500) ECO-47: Replace Older Transformers $48,300 $0 ($59,800) ($11,500) Totals $273,100 ($38,600) ($2,250,700) ($2,016,200) Note: Negative numbers, in parenthesis, represent savings. City and Borough of Juneau 5 Mendenhall WWTP Energy Audit

8 Energy Savings The following table shows the current energy costs and projected ECO energy savings. Table 1-2: ECO Annual Energy Cost Savings Fuel Oil Electricity Total Existing Energy Costs $215,000 $240,000 $455,000 High Priority ECOs ECO-30: Turn Off SBR Lag Boiler ($5,000) ($0) ($5,000) ECO-31: Turn Off Boilers in Summer ($3,000) ($0) (3,000) ECO-32: Reduce UV Output to Two Banks ($0) ($8,000) ($8,000) ECO-33: Repair AHU-101/102 Heat Recovery ($19,000) $600 ($18,000) ECO-34: Repair AHU-103/104 Heat Recovery ($19,000) $600 ($18,000) ECO-35: Install ABF Boiler Room Heat Recovery ($2,000) ($0) ($2,000) ECO-36: Replace Clothes Washer ($0) ($400) ($400) ECO-37: Install AHU-105 Heat Recovery ($13,000) $3,000 ($10,000) ECO-38: Install Automatic Valves on Unit Heaters ($2,000) ($0) ($2,000) ECO-39: Replace HVAC Motors ($0) ($2,000) ($2,000) Medium Priority ECOs ECO-40: Convert to Variable Speed Hydronic Pumping ($0) ($3,000) ($3,000) ECO-41: Insulate Collections Building Walls ($3,000) ($0) ($3,000) ECO-42: Install MCC Room Heat Recovery ($2,000) ($0) ($2,000) ECO-43: Replace Collections Building Windows ($400) ($0) ($400) ECO-44: Replace Process Motors ($0) ($1,000) ($1,000) ECO-45: Insulate Collections Building Roof ($1,000) ($0) ($1,000) ECO-46: Upgrade SBR Building Lighting ($0) ($100) ($100) ECO-47: Replace Older Transformers ($0) ($3,000) ($3,000) ECO Totals ($69,000) ($13,000) ($82,000) (32%) (13%) (18%) Note: Negative numbers, in parenthesis, represent savings. The above table shows that the high and medium priority ECOs will provide an annual energy cost savings of 18%. Additionally, the behavioral and operational ECOs will also provide energy savings. These savings are not included in the predictions because their level of implementation cannot be accurately estimated. One ECO of note is ECO-6 (Optimize SBR Blower Operation) predicts $2,000 to $5,000 in annual electric savings if blower operation is reduced 10% or 20%, respectively. City and Borough of Juneau 6 Mendenhall WWTP Energy Audit

9 FACILITY GUIDELINES The following guidelines are based on the findings of the energy audit. Given the long service life of the plants, they should also be applied when possible as part of ongoing facility maintenance or renovation. Building Envelope None of the existing buildings are optimally insulated for the current cost of heat. The optimal insulation level depends upon the type of construction and the cost of heat, which varies with each building. An envelope optimization analysis should be performed when determining insulation levels for buildings. Lighting Most of the spaces are occupied a minimal number of hours each year. Turning off the lighting in these spaces will produce immediate energy cost savings. Inexpensive fluorescent T-8 lighting is optimal for most spaces. High bay fluorescent lighting is more efficient and has a quicker startup than metal halide lighting. Exterior lighting operates about 50% of the year. Energy efficient metal halide lighting is recommended with integral photocells. Photocell control should be fine tuned so the lighting is off during daylight hours. Transformers The buildings are supplied with 480V power. The benefit of a 480V service, when compared to 208V/120V service, is that smaller conductors are required and motors are slightly more efficient at higher voltages. The downside is the investment in a step-down transformer that is downstream of the utility meter. The losses of the step-down transformer are paid by the owner. Most transformer losses are converted to heat. The heat gain to the building can be beneficial during the heating season, but is inefficient when it is not needed. There are two methods for reducing the transformer losses. First, the transformer should be right-sized. Losses are typically a percentage of the transformer capacity, so a smaller transformer costs less and has smaller losses. Second, highly energy efficient transformers should be used. Recommendations for transformers are: Right-size the transformer by establishing reasonable estimates of loads. Use energy efficient transformers. Transformers that are 15 kva and larger should meet the energy efficiency requirements of NEMA Standard TP Locate the transformer near the floor where the heat output will create useful convective currents, spreading the heat though the facility. City and Borough of Juneau 7 Mendenhall WWTP Energy Audit

10 Operational Guidelines The following guidelines were developed based on energy conservation opportunities in the existing facilities and operations. The guidelines are recommended to improve the energy performance of the water system. Pumps The pumps should be right-sized and selected for optimal efficiency. Variable speed pumping allows pumps to operate for longer periods at lower flow rates, which reduces energy consumption and demand charges. The many energy and operational benefits of variable speed pumping should be implemented where appropriate. Motors Many of the motors are less efficient than modern motors. Replacing the motors with NEMA Premium efficient motors will reduce energy consumption and demand charges. The energy cost of operating a motor usually exceeds the purchase price. Whether an investment in an energy efficient motor should be made depends upon the cost of the motor, cost of electricity, and the number of operating hours each year. There is no one guideline that can cover all of these variables. NEMA Premium motors may not be available for the required frames. The following table provides the full load efficiencies of standard and NEMA Premium motors. Table 1-3: Motor Full Load Efficiency Horsepower Standard NEMA Premium to to to to to to to to to to to to to to to to City and Borough of Juneau 8 Mendenhall WWTP Energy Audit

11 Demand Control AEL&P determines the electric demand by averaging demand over a continuously sliding fifteenminute window. The highest fifteen-minute average during the billing period determines the peak demand. As a rule of thumb, each kw of peak load adds $10 in demand charges to the monthly electric bill. The following strategies are recommended to minimize demand: Implement the above facility and operational guidelines at each facility. Use variable speed pumping and equipment and establish control sequences that operate them for longer periods at lower output. For systems with redundant pumps and equipment, limit simultaneous operation of pumps to emergencies and testing. Perform back-to-back tests within one billing cycle so the added demand charges are applied to a single month s bill. Use NEMA Premium energy efficient motors when operating hours warrant the investment. Right-size the equipment such as pumps, transformers, and electric heaters. SUMMARY The MWWTP energy systems are in good condition and appear to be well maintained. The exception is the HVAC control system in the SBR building, which has failed. The age of the plant played a factor into the number of ECOs. There is financial incentive to invest in energy efficiency and obtain an 18% reduction in energy costs. The energy auditor would like to express appreciation to the MWWTP operation and maintenance personnel who provided assistance during this project. Their knowledge of the plant energy systems and interest in energy efficiency was invaluable. City and Borough of Juneau 9 Mendenhall WWTP Energy Audit

12 The page intentionally left blank City and Borough of Juneau 10 Mendenhall WWTP Energy Audit

13 Section 2 Introduction This report presents the findings of an energy audit of the City and Borough of Juneau Mendenhall Wastewater Treatment Plant (MWWTP). The purpose of the energy audit is to identify energy conservation opportunities (ECOs) and determine if investments in energy efficiency will provide a life cycle savings. The findings were gathered through on-site observations, review of construction documents, and interviews with operations and maintenance personnel. The energy audit was performed by Jim Rehfeldt, P.E. of Alaska Energy Engineering LLC with technical assistance by Jim Dorn, P.E. of Carson Dorn, Inc. PLANT DESCRIPTION The Mendenhall Wastewater Treatment Facility processed 840 million gallons of influent in Wastewater flows through the following process: Influent Pump Station: The influent flows into the plant, solids are ground and a sieve removes rags. The flow settles in the influent well and is lifted into tea cup strainers that remove grit. The grit falls into a grit clarifier where it is removed. Sequencing Batch Reactors (SBRs): From the influent pump station, the water is distributed to one of eight SBRs where it is treated using aeration blowers and jet circulation pumps. UV Treatment: When an SBR completes a reaction cycle, the water is decanted and disinfected by UV treatment prior to discharge to the Mendenhall River. Sludge Process: Sludge from the SBRs is stored in the sludge storage tank. The sludge is dewatered in a belt filter press and trucked to the JDWWTP for incineration. ENERGY USE SUMMARY Electricity Electricity is billed under AEL&P s Rate 34, Large Government that charges for both electrical consumption (kwh) and peak electric demand (kw). Electrical consumption is the amount of energy consumed and electric demand is the rate of consumption. AEL&P determines the electric demand by averaging demand over a continuously sliding fifteen-minute window. The highest fifteen-minute average during the billing period determines the peak demand. AEL&P also charges for power factor. If the power factor falls below 95% lagging, the customer must take corrective steps to return the power factor to 95% or higher. If the average power factor is less than 95% lagging, the billing demand charge will be increased by one percent (1%) for each percent or fraction thereof that the average power factor is less than ninety-five percent (95%) lagging. Power factor correction is installed at the plant, and there are no power factor charges being assessed. City and Borough of Juneau 11 Mendenhall WWTP Energy Audit

14 Table 2-1 lists the current electric charges: Table 2-1: AEL&P Large Government Rate Charge 1 On-peak (Nov-May) Off-peak (June-Oct) Energy Charge per kwh Demand Charge per kw $11.53 $7.35 Service Charge per month $99.24 $99.24 Four years of electrical energy usage data from AEL&P is included in Appendix A. Energy consumption From 2006 to 2008, consumption averaged 3,000,000 kwh per year. The use dropped considerably between 2005 and 2006 after the thickened sludge tank and centrifuge was removed from service. Plant flows are highest in summer, yet energy use if highest during colder months. This is because cooler influent requires a longer treatment process that is more energy intensive. Electrical Demand From 2006 to 2008, demand averaged 497 kw per month and has been consistent. The demand was 75 kw higher in 2005 due to the centrifuge that was removed from service at the end of Costs During , annual energy costs averaged $240,000 per year. The monthly electric bill has the following breakdown. 1. Energy consumption (kwh) = 75% 2. Electrical demand (kw) = 24% 3. Customer charges = 1% Electricity has an effective cost (sum of energy and demand charges) of 8.0 per kwh. The plant has an annual load factor of 70%. This is the ratio of the average load (kw) to the peak load (kw). The plant operates at a high load factor, which indicates efficient operation, because loads are on for long periods and are not cycled for short durations. The primary benefit of a high load factor is lower demand charges, which result in a low effective cost per kwh. Fuel Oil Two fuel oil tanks supply the SBR Building boilers and hot water heater, the ABF Plant boiler, and the emergency generator. CBJ records show a consumption of 113,000 gallons of fuel oil in City and Borough of Juneau 12 Mendenhall WWTP Energy Audit

15 METHODOLOGY Energy Conservation Opportunities (ECOs) Energy conservation opportunities were identified by evaluating the energy systems and the operating parameters of the water system. The process for identifying the ECOs acknowledges the limitations of modifying existing buildings and systems, most of which were constructed when energy costs were much lower. The ECOs represent practical measures to improve the energy efficiency of the system. Life Cycle Cost Analysis The ECOs are evaluated using life cycle cost analysis to determine if an energy efficiency investment will provide a savings over a 25-year life. The analysis incorporates construction, replacement, maintenance and repair, and energy costs to determine the total cost over the life of the ECO. Future maintenance and energy cash flows are discounted to present worth using escalation factors for general inflation, energy inflation, and the value of money. The methodology is based on the National Institute of Standards and Technology (NIST) Handbook 135 Life Cycle Cost Analysis. Life cycle cost analysis is preferred to simple payback for facilities that have long often perpetual service lives. Simple payback, which compares construction cost and present energy cost, is reasonable for short time periods of 2-4 years, but yields below optimal results over longer periods because it does not properly account for the time value of money or the effect inflation has on operating budgets. Accounting for energy inflation and the cost of money properly values the true cost of facility ownership and seeks to minimize the total cost over its life. Appendix C contains the life cycle cost calculations of each ECO. Construction Costs The cost estimates are derived based on a preliminary understanding of the scope of each ECO as gathered during the walk-through audit. The construction costs assume in-house labor at $60 for work typically performed by maintenance staff and contract labor for larger projects and electrical work. The estimates assume some efficiency gain by being incorporated into larger, energy efficiency or other construction projects. This will spread mobilization costs over a number of ECOs and minimize costs. When ECOs are taken for implementation, the cost estimate should be revisited once the scope and preferred method of performing the work has been determined. It is possible some ECOs will not provide a life cycle savings once the scope is finalized. Maintenance Costs Maintenance costs are based on in-house labor using historical maintenance efforts and industry standards. Maintenance costs are determined for the 25-year life of each ECO and represent realistic levels of effort to maintain the relative systems. Energy Analysis The energy performance of each ECO is evaluated using operating parameters of the water system and facilities. Appendix B contains the energy analysis calculations. City and Borough of Juneau 13 Mendenhall WWTP Energy Audit

16 Prioritization A prioritized ranking of the ECOs was calculated for each building using the following formula: Prioritization Factor = Life Cycle Savings / Capital Costs This factor puts weight on the capital cost of an ECO, which is aligned with budgeting realities that allow early implementation of low cost improvements while higher cost ECOs must wait for funding and implementation. The ECOs are grouped into the following prioritized categories: Behavioral or Operational: ECOs that need minimal capital investment but require operational or behavioral changes. A life cycle cost analysis is not performed of these ECOs because the energy savings is difficult to quantify and a life cycle savings is certain. High Priority: ECOs that provide a life cycle savings over 200% of the capital cost. Medium Priority: ECOs that provide a life cycle savings up to 200% of the capital cost. Low Priority: ECOs that will save energy but do not provide a life cycle savings. Economic Factors Economic factors are significant to the findings and should undergo careful scrutiny. Nominal Interest Rate: This is the nominal rate of return on an investment without regard to inflation. The analysis uses a rate of 5.0% which is the current cost of bonds for CBJ capital improvement projects. Inflation Rate: This is the average inflationary change in prices over time. The analysis uses an inflation rate of 3.0% which is the consumer price index average of the past 25-years. Real Discount Rate: This is the actual rate of return when the inflation rate is considered. The analysis uses a real discount rate of 1.9% which is a calculated value derived from the nominal interest rate and the inflation rate. Economic Period: This is the period of time in which costs are considered. The analysis is based on a 25-year economic period with construction beginning in Electricity The electric rates are determined by Alaska Electric Light & Power Company (AEL&P) based on the provisions of their tariff. AEL&P is a privately owned utility regulated by the Regulatory Commission of Alaska. Power generation facilities utilized by AEL&P include both hydroelectric and diesel plants. Currently, the hydroelectric plants generate most of the electricity and the diesel plants provide backup. Over recent history, electricity inflation has been less than 1% per year, which has lagged general inflation. This trend has been discontinued in recent years as fuel oil price increases led to more electric heating loads. The winter of 2007/2008 is the first extended period where AEL&P had to supplement with diesel generation. This caused a temporary Power Cost Adjustment of 1.2 per kwh. In the fall of 2009, the new Lake Dorothy Hydroelectric Facility will begin producing power. The power from Lake Dorothy will be more expensive than power from the existing hydroelectric facilities. It is assumed that the community will consume most of the Lake Dorothy Phase 1 power in the near future and that the blended generation cost will raise electric rates 1.5 per kwh. The life cycle cost analysis includes a 1.5 /kwh increase in electric costs. City and Borough of Juneau 14 Mendenhall WWTP Energy Audit

17 Even with Lake Dorothy, electric heating loads are likely to continue to place demands on the hydroelectric generation facilities. A recent CBJ energy balance report indicates that Juneau s heating loads which are currently met with fuel oil are 175% greater than non-heating electrical loads. Thus, there is a large potential heating load that may see some conversion to electricity if fuel oil heating prices rise above electric heating prices. In essence, electricity inflation is effected by fuel oil inflation. The life cycle cost analysis uses an electric inflation of 2.5%, which is higher than the historic average to account for future electric heating price pressures. Fuel Oil The CBJ is currently paying $1.90 of a gallon of heating fuel. Prices have stabilized after dropping dramatically over the past year. Fuel oil inflation has historically averaged 6% per prior to the rapid escalation and de-escalation of prices over the past five years. The analysis assumes the fuel oil inflation will once again continue to inflate at 6% Table 2-2: Summary of Economic and Energy Factors Factor Rate or Cost Factor Rate or Cost Nominal Discount Rate 5.0% Electricity Current rates /kwh General Inflation Rate 3.0% Electricity Inflation 2.5% Real Discount Rate 1.9% Fuel Oil Cost $1.90/gal Fuel Oil Inflation 6% City and Borough of Juneau 15 Mendenhall WWTP Energy Audit

18 This page intentionally left blank City and Borough of Juneau 16 Mendenhall WWTP Energy Audit

19 Section 3 Buildings This section describes energy conservation opportunities associated with the buildings. The individual buildings are: SBR Building UV Disinfection Building Belt Filter Press Building Collections Office ABF Plant Building Jet Truck Building Lube Oil Storage Building SBR BUILDING Building Envelope Table 3-1: Building Envelope Component (inside to outside) R-value Remarks Walls Gyp. Bd.; metal studs; ½ sheathing; 2 ins. panel R-11 Low R-value Roof Structure; ¾ plywood; 3 rigid; metal roof R-17 Low R-value Floor slab Concrete slab-on-grade R-2 No insulation Perimeter Concrete footing; 2 rigid, inside face R-10 Windows Insulated metal frame; dbl. pane R-2.3 Low R-value Doors Main Entrance Insulated metal frame and door; dbl. pane window R-3 Grit Clarifier Insulated metal frame and door R-4 Grit Clarifier OH insulated metal door R-1 Low R-value; No bottom weather-stripping Electrical Insulated metal frame and dbl door R-4 No center weatherstripping Boiler Room Insulated metal frame and dbl door R-4 No center weatherstripping Shop Insulated metal frame and door; dbl. pane window R-3 No weather-stripping Shop OH insulated metal door R-1 Low R-value; No weatherstripping Stairs Insulated metal frame and door R-4 No weather-stripping Generator Insulated metal frame and door R-4 No weather-stripping Generator Insulated metal frame and dbl door R-4 No weather-stripping City and Borough of Juneau 17 Mendenhall WWTP Energy Audit

20 Analysis The walls and roofs are under insulated. Insulation can be added but the cost of removing items from the surfaces, adding insulation, and installing wallboard typically exceeds the life cycle energy savings. The floor slabs are under insulated. However, there is no economical way to add insulation to the floor slabs. There is no economic incentive to replace doors and frames with thermally broken units. Door weather-stripping can be installed or upgraded to seal the opening, minimizing infiltration. Heating System The heating plant consists of two oil-fired, low-pressure steam boilers. The steam is converted to hydronic heating water in two shell and tube steam/hot water heat exchangers. The hydronic heating system has a primary/secondary configuration and circulates a glycol antifreeze solution. Glycol pump HGFP-1 maintains system pressure by feeding glycol into the system. Primary pumps HWP-101/102 operate in a lead/standby configuration and circulate heating water through the heat exchangers. Secondary pump HWP-103 supplies the AHU-101 and 102 heating coils. Secondary pumps HWP-111A/B operate in a lead/standby configuration and supply the Jet Truck Garage unit heater. Secondary pumps HWP-112A/B operate in a lead/standby configuration and supply the SBR hydronic heating units. Secondary pumps HWP-114A/B operate in a lead/standby configuration and supply the Disinfection Building hydronic heating units. Analysis Both boilers are hot year-round. For most of the year, one boiler is capable of meeting the heating load. Keeping the unneeded second boiler on-line increases standby and cycling losses. Secondary pumps HWP-111A/B are very oversized for the heating loads of the Tanker Garage. Converting the secondary system to a single set of variable speed pumps will decrease pumping costs. None of the unit heaters has an automatic valve to shut off the heating water flow when heat is not required. The cabinet unit heater in the main entrance vestibule does not have a thermostat control. The vestibule was 75 F on a 35 F day, which is higher than needed. The Blower Room temperature is so warm that the cooling fans in the blower enclosures are operating even when the blower is not. City and Borough of Juneau 18 Mendenhall WWTP Energy Audit

21 Ventilation Systems West SBR: AHU-101 is a constant airflow cabinet fan that supplies full outside air. AHU-102 is a constant flow cabinet fan that exhausts air from the room. AHU-101 and AHU-102 have a recovery system that extracts heat from the AHU-102 exhaust air and preheats the AHU-101 supply air. Pump HWP-103 circulates water between the two heat recovery coils. Exhaust fan EF-112 is a constant airflow fan that provides additional exhaust. East SBR: AHU-103 is a constant airflow cabinet fan that supplies full outside air. AHU-104 is a constant flow cabinet fan exhausting air from the room. AHU-103 and AHU-104 have a heat recovery system that extracts heat from the AHU-104 exhaust air and preheats the AHU-102 supply air. Pump HWP-104 circulates water between the two heat recovery coils. Exhaust fan EF-111 is a constant airflow fan that provides additional exhaust. Blower Room: AHU-105 is a constant volume cabinet fan that supplies full outside air to the room. EF-101 is a constant flow system exhausting air from the room. Influent Pump Station: AHU-107 is a constant flow cabinet fan that supplies full outside air to the room. EF-113 is a constant flow in-line fan exhausting air from the room. Laboratory: AHU-109 is a constant flow cabinet fan supplying mixed air to the room. The unit has a mixing box, filter section, face and bypass dampers, heating coil, cooling coil, and supply fan. EF-108 is a constant flow in-line exhaust fan serving the lab canopy hoods. Offices: AHU-110 is a constant flow system supplying mixed air to the rooms. The unit has a mixing box, filter section, face and bypass dampers, heating coil, cooling coil, and supply fan. Four reheat coils provide zone temperature control. EF-105A is a ceiling exhaust fan serving the 2 nd Floor Men s Toilet. EF-105B is a ceiling exhaust fan serving the 2 nd Floor Women s Toilet. EF-105C is a ceiling exhaust fan serving the 1 st Floor Toilet. City and Borough of Juneau 19 Mendenhall WWTP Energy Audit

22 Pipe Gallery: AHU-112 is a constant airflow cabinet fan that supplies full outside air. AHU-112 has a heat recovery coil. AHU-114 is a constant flow cabinet fan exhausting air from the room. AHU-114 has a heat recovery coil. Pump HWP-105 circulates water in a heat recovery loop between the two heat recovery coils. Boiler Room: SF-116 is a constant flow cabinet fan that supplies full outside air to the room. EF-114 is a constant flow fan that transfers boiler room heat to the adjacent shop. MCC Room: EF-104 is a wall propeller fan that exhausts air from the room. A makeup air louver with automatic damper provides makeup air when the fan operates. Shop: EF-106 is a wall propeller fan exhausting air from the room. Electric Room: EF-107 is a wall propeller fan that exhausts air from the room. A makeup air louver with automatic damper provides makeup air when the fan operates. Pipe Gallery #2: EF-109 is an in-line fan that exhausts air from the room. A makeup air louver with heating coil provides tempered makeup air when the fan operates. Pipe Gallery #3: EF-110 is an in-line fan that exhausts air from the room. A makeup air louver with heating coil provides tempered makeup air when the fan operates. Analysis The airflow rates in the SBR Rooms and Blower Rooms are less than the 12 ACH that is required by current codes. As such, there is no opportunity to reduce airflow and save energy. The heat recovery loop between AHU-101 and AHU-102 is not in use. Restoring HWP-103 to operation and making the loops operational will reduce heating loads. The heat recovery loop between AHU-103 and AHU-104 is not in use. Restoring HWP-104 to operation and making the loops operational will reduce heating loads. There is no heat recovery loop installed for AHU-105 and EF-101. Adding heat recovery will save energy. Exhaust fans EF-105A/B/C are controlled from wall switches. Automatic control will ensure they are off when not needed. Exhaust Fans EF-111 and EF-112 were added in 1990 because the systems did not operate properly. The systems should be retrocommissioned and the EFs removed. Cooling System An air-cooled chiller supplies chilled water to the cooling coils in AHU-109 and AHU-110. Cooling pump HWP-108 circulates glycol chilled water to the coils. Cooling glycol feed pump CGFP-1 maintains system pressure by feeding glycol into the system. Analysis The chiller did not operate in It is reported to be in poor condition due to Freon leaks. City and Borough of Juneau 20 Mendenhall WWTP Energy Audit

23 Domestic Hot Water Heating An oil-fired, 86-gallon hot water heater supplies domestic hot water. Analysis The setpoint is set at 130 F. Turning it down to 120 F will reduce heat loss and protect from scalding. Fuel Oil System Two buried fuel oil tanks, located remotely from the building, supply fuel oil for the SBR boilers and the ABF boiler. Each tank has a submersible fuel oil pump, FOP-109 and FOP-110, which operates in a lead/standby configuration. The pumps circulate fuel between the boiler burners and the tanks. Analysis A fuel oil pump operates continuously. Installing a day tank in each boiler room will significantly reduce pump operation. HVAC Automatic Controls The HVAC system controls consist of an electric control system. Analysis The entire control system is out of calibration. Many thermostats setpoints are fully up or down and automatic valves and dampers are not controlled. The result is the building space temperatures are much higher than necessary, resulting in a considerable energy penalty due to the large outside airflow rates in the building. The lack of a central control and monitoring station makes it difficult to verify that the systems are operating properly. City and Borough of Juneau 21 Mendenhall WWTP Energy Audit

24 Lighting Table 3-2: Lighting Fixtures and Lamps Room Fixture No. / Type Lamp No. / Type Control Remarks Office Area 106 / Recessed 4 / T8 Switch West SBR 14 / Pendant 1 /100w HPS Switch 50% delamped 6 / Pendent 1 / 250 HPS Switch 4 / Suspended 1 / 250w HPS Switch East SBR 14 / Pendant 1 /100w HPS Switch 50% delamped 6 / Pendent 1 / 250 HPS Switch 4 / Suspended 1 / 250w HPS Switch Blower Room 18 / Pendant 1 / 250w HPS Switch 50% delamped MCC Room 12 / Suspended 2 / T8 Switch Stairway 3 / surface 2 / T12 Always on Inefficient Grit Clarifier 6 / Pendant 1 /100w HPS Switch Influent Pump Station 6 / Pendant 1 /100w HPS Switch Pipe Gallery 12 / suspended 2 / T12 Switch Inefficient Tool Room 2 / Surface 2 / T8 Switch Electrical Room 5 / Suspended 2 / T8 Switch 1 st Floor Toilet 1 / Recessed 2 / T8 Switch Boiler Room 16 / Suspended 2 / T8 Switch Shop 47 / Suspended 2 / T8 Switch Generator 15 / Suspended 2 / T8 Switch Exterior 10 / Wall 1 / 70w HPS Photocell Analysis The remaining interior T12 and incandescent lighting has a much lower efficacy than T8 or CFL lighting. Much of the lighting is on continuously, even in seldom-occupied areas like the Boiler Room and Pipe Gallery. Turning off lighting will reduce energy. City and Borough of Juneau 22 Mendenhall WWTP Energy Audit

25 Electrical Equipment There is a refrigerated water cooler in the 2nf floor hallway. The lab has a dryer and a furnace for testing samples. There is a top loading washing machine in the Laundry Room. Analysis The water supply in Juneau is sufficiently cool enough that a refrigerated cooler is not necessary. The lab fryer and furnace is continually hot at 105 C and 530 C, respectively, even though the equipment is only in use during the normal workweek. Turning it off at night and on weekends will save energy. The top-loading washing machine is less efficient and uses more water than a front-loading washing machine. Backup Generator The backup generator discharges cooling air through an exhaust duct and louver. Analysis The uninsulated exhaust duct and louver losses heat to outside. Insulating the duct will reduce the heat loss. Transformers The building electric supply is 480V. The following transformers step down the 480V building power to obtain 208V/120V power. Table 3-3: Transformers Transformer Size Remarks Loadcenter LC1 30 kva Less efficient Loadcenter LC2 10 kva No replacement Loadcenter LC3 15 kva Less efficient Loadcenter LC5 15 kva Less efficient Loadcenter LC6 25 kva Less efficient Centrifuge 20 kva Not in service Shop 45 kva Less efficient Fuel Oil Pump FOP kva No replacement Fuel Oil Pump FOP kva No replacement Analysis The larger transformers are less efficient than current equipment. City and Borough of Juneau 23 Mendenhall WWTP Energy Audit

26 Motors Table 3-4: Motors Service Horsepower Efficiency NEMA Premium Remarks HWP Less efficient HWP Less efficient HWP Less efficient HWP Less efficient HWP Less efficient HWP-112A Less efficient HWP-112B Less efficient HWP-111A Less efficient HWP-111B Less efficient HWP-114A Less efficient HWP-114B Less efficient AHU Less efficient AHU Less efficient AHU Less efficient AHU Less efficient AHU Less efficient AHU Less efficient AHU Less efficient AHU Less efficient AHU Less efficient AHU Less efficient EF Less efficient EF Less efficient 1. New motor efficiency is based on NEMA Premium MG-1 efficiency motors. Analysis Replacing the less efficient motors with NEMA Premium efficient motors will reduce energy consumption. Some specialized service motors may not be available as NEMA Premium. City and Borough of Juneau 24 Mendenhall WWTP Energy Audit

27 DISINFECTION BUILDING Building Envelope Table 3-5: Building Envelope Component (inside to outside) R-value Remarks Walls FRP Panel; 2x6 wood studs with batt; metal siding R-19 Windows Mtl frame; double pane R-1.5 Low R-value; no thermal break Roof Attic with batt insulation R-30 Low R-value Floor slab concrete slab on grade R-2 No insulation Perimeter concrete footing, 2 rigid R-10 Low R-value Doors Entrance Insulated metal door and frame R-5 Poor weather-stripping Overhead Insulated metal door R-4 Analysis The walls and roofs are under insulated. Insulation can be added but the cost of removing items from the surfaces, adding insulation, and installing wallboard is prohibitive to obtaining a life cycle savings. The floor slabs are under insulated. However, there is no economical way to add insulation to the floor slabs. There is no economic incentive to replace doors and frames with thermally broken units. Door weather-stripping can be installed or upgraded to seal the opening, minimizing infiltration. Heating System The building is heated by the SBR Building boilers. Hydronic heating water circulates through unit heaters located in each building. Wall thermostats control all of the unit heaters. The thermostat setpoints vary from 52 F to 70 F. Analysis The unit heaters do not have an automatic valve to turn off the hydronic flow when heating is not required. Reducing the heating setpoint to 55 F will save energy while maintaining sufficient warmth to prevent freezing and control humidity. The Jet Truck Garage overhead door and unit heater are not interlocked to turn off the heat when the door is open. City and Borough of Juneau 25 Mendenhall WWTP Energy Audit

28 Cooling System Several of the rooms have a wall mounted exhaust fan with a backdraft damper and louver and a makeup air louver with backdraft damper. The fan operates when the room temperature exceeds the setpoint. Analysis Several of the backdraft dampers do not seal tightly. Lighting Table 3-6: Lighting Fixtures and Lamps Room Fixture No. / Type Lamp No. / Type Control Remarks Interior Rooms 23 / Suspended 2 / T8 Switch UV Room 3 / Suspended 1 / 150w HPS Switch 1 / Suspended 2 / T8 - Always on Tanker Garage 3 / Suspended 1 / 150w HPS Switch Exterior 8 / Surface 1 / 50w HPS Photocell Transformers The building electric supply is 480V power. A 75 kva transformer steps down the 480V building power to obtain 208V/120V power. Analysis The transformer is less efficient than current equipment. City and Borough of Juneau 26 Mendenhall WWTP Energy Audit

29 BELT FILTER PRESS BUILDING Building Envelope Table 3-7: Building Envelope Component (inside to outside) R-value Remarks 1 st Fl. Wall Gyp. bd.; 2 rigid; CMU block; metal siding R-12 Low R-value 2 nd Fl. Wall 6 metal studs, insulated wall panel R-8 Low R-value Roof Metal frame, insulated roof panel R-14 Low R-value Floor slab concrete slab on grade R-2 No insulation Perimeter concrete footing, 2 rigid R-10 Low R-value Analysis The walls and roofs are under insulated. Insulation can be added but the cost of removing items from the surfaces, adding insulation, and installing wallboard is prohibitive to obtaining a life cycle savings. The floor slabs are under insulated. However, there is no economical way to add insulation to the floor slabs. Heating System Heat is supplied by the ABF Building boiler. Hydronic heating water circulates through unit heaters. Wall thermostats control all of the unit heaters. Analysis The unit heaters do not have automatic valves to turn off the hydronic flow when heat is not needed. Lighting Table 3-8: Lighting Fixtures and Lamps Room Fixture No. / Type Lamp No. / Type Control Remarks Interior Rooms 23 / Suspended 2 / T8 Switch UV Room 3 / Suspended 1 / 150w HPS Switch 1 / Suspended 2 / T8 - Always on Tanker Garage 3 / Suspended 1 / 150w HPS Switch Exterior 8 / Surface 1 / 50w HPS Photocell City and Borough of Juneau 27 Mendenhall WWTP Energy Audit

30 Transformers The building is supplied with 480V power for the UV equipment. A 75 kva transformer is installed to step down the 480V building power to obtain 208V/120V power. Analysis The transformer is less efficient than current equipment. ABF PLANT Building Envelope Table 3-9: Building Envelope Component (inside to outside) R-value Remarks Walls Metal frame; 2 fiberglass insulation; metal siding R-8 Low R-value Roof Metal frame; 2 fiberglass insulation; metal roof R-8 Low R-value Floor slab Concrete slab-on-grade R-2 No insulation Perimeter Concrete footing; 2 rigid, inside face R-10 Doors Uninsulated metal door and frame R-1 Low R-value; no thermal break; no weatherstripping OH Door Uninsulated metal door and frame R-1 Low R-value; no thermal break; no weatherstripping Analysis The walls and roofs are under insulated. Insulation can be added but the cost of removing items from the surfaces, adding insulation, and installing wallboard is prohibitive to obtaining a life cycle savings. The floor slabs are under insulated. However, there is no economical way to add insulation to the floor slabs. There is no economic incentive to replace doors and frames with thermally broken units. Door weather-stripping can be installed or upgraded to seal the opening, minimizing infiltration. Heating System An oil-fired boiler supplies hydronic heating water to the ABF Building and the Belt Filter Press Building. Pumps CP-1 and CP-2 circulate hydronic heating water to unit heaters located in the building. Wall thermostats, set at 65 F, control all of the unit heaters. City and Borough of Juneau 28 Mendenhall WWTP Energy Audit

31 Analysis There is uninsulated hydronic heating piping in the boiler room. Given the poor thermal envelope of the building, reducing the indoor temperature to 55 F will save significant amount of energy. Ventilation Systems There are several cooling exhaust systems with louvers. These systems are no longer operational. Analysis The exhaust ducts, fans, and louvers are not sealed and there are noticeable leaks to the outside. Remove the units and seal the openings to minimize heat loss. Lighting Table 3-10: Lighting Fixtures and Lamps Room Fixture No. / Type Lamp No. / Type Control Remarks Plant 21 / Pendent 1 / 250w HPS Switch - Work bench 5 / Suspended 2 / T8 Switch - JET TRUCK GARAGE Building Envelope Table 3-11: Building Envelope Component (inside to outside) R-value Remarks Walls Gyp. bd.; 2x6 with batt; metal siding R-19 Roof Attic with batt insulation R-30 Low R-value Floor slab concrete slab on grade R-2 No insulation Perimeter concrete footing, 2 rigid R-10 Low R-value Doors OH Door Insulated metal door R-2 Low R-value; No thermal break; No weatherstripping Door Insulated metal frame and door R-3 Low R-value; No thermal break; No bottom weather-stripping City and Borough of Juneau 29 Mendenhall WWTP Energy Audit

32 Analysis The walls and roofs are under insulated. Insulation can be added but the cost of removing items from the surfaces, adding insulation, and installing wallboard is prohibitive to obtaining a life cycle savings. The floor slabs are under insulated. However, there is no economical way to add insulation to the floor slabs. There is no economic incentive to replace doors and frames with thermally broken units. Door weather-stripping can be installed or upgraded to seal the opening, minimizing infiltration. Heating System The SBR Building boiler heats the building. Hydronic heating water circulates through a unit heater controlled by a wall thermostat. The setpoint is 60 F. Analysis The unit heater does not have an automatic valve to turn off the hydronic flow when heat is not needed. The thermostat is inaccurate; the room was 71 F. Lighting Table 3-12: Lighting Fixtures and Lamps Room Fixture No. / Type Lamp No. / Type Control Remarks Garage 8 / Surface 2 / T12 Switch 8 lamps LUBE OIL BUILDING Building Envelope There is no data on the building envelope. Heating System Two electric unit heaters keep the building warm. The building temperature is 57 F. City and Borough of Juneau 30 Mendenhall WWTP Energy Audit

33 Lighting Table 3-13: Lighting Fixtures and Lamps Room Fixture No. / Type Lamp No. / Type Control Remarks Garage 4 / Surface 1 / 75w HPS Switch COLLECTIONS BUILDING Building Envelope Table 3-14: Building Envelope Component (inside to outside) R-value Remarks Walls 8 concrete block R-2 Low R-value Windows Wood casement; single pane R-1.0 Low R-value; poor weather-stripping Roof Wood roof deck, 1 rigid, built-up roof R-7 Low R-value Floor slab concrete slab on grade R-2 No insulation Perimeter concrete footing, 1 rigid R-5 Low R-value Doors Main Entrance Insulated metal door and frame; single pane window R-1.5 Low R-value; no thermal break; no weatherstripping Break Room Insulated metal door and frame; single pane window R-1.5 Low R-value; no thermal break; no weatherstripping Back Office Insulated metal door and frame R-5 No weather-stripping Back Door Insulated metal door and frame; single pane window R-1.5 Low R-value; no thermal break; no weatherstripping Analysis The walls and roofs are under-insulated. Adding insulation to the exterior is the best option for improving the walls. The floor slabs are under insulated. However, there is no economical way to add insulation to the floor slabs. There is no economic incentive to replace doors and frames with thermally broken units. Door weather-stripping can be installed or upgraded to seal the opening, minimizing infiltration. City and Borough of Juneau 31 Mendenhall WWTP Energy Audit

34 Heating System The ABF Plant boiler heats the building. Hydronic heating water circulates through baseboard and unit heaters. Electric heaters also supply supplemental heating on cold days. Wall thermostats control the hydronic heaters. Integral thermostats control the electric heaters. The thermostat setpoints varied from 70 F to 75 F. Analysis The hydronic and electric heaters have separate thermostats set at different temperatures. Larger hydronic heaters controlled by a single thermostat will improve thermal comfort and temperature control. The unit heaters do not have automatic valves to turn off the hydronic flow when heat is not needed. Domestic Hot Water System An electric hot water heater supplies the building. Analysis The heater is located in a cold room. Adding an insulating blanket will reduce heat loss. The unit heaters do not have an automatic valve to turn off the hydronic flow when heat is not needed. Lighting Table 3-15: Lighting Fixtures and Lamps Room Fixture No. / Type Lamp No. / Type Control Interior Rooms 33 / Surface 2 / T12 Switch City and Borough of Juneau 32 Mendenhall WWTP Energy Audit

35 Section 4 Wastewater Treatment Process The Mendenhall Wastewater Treatment Facility processed 800 million gallons of influent in Wastewater flows through the following process: Influent Pump Station: The influent flows into the plant, solids are ground and a sieve removes rags. The flow settles in the influent well and the influent pumps lift it to tea cup strainers that remove the grit. The grit falls into a grit clarifier that removes it for disposal. Sequencing Batch Reactors (SBRs): From the influent pump station, the water distributes to one of eight SBRs where it is treated using aeration blowers and jet circulation pumps. UV Treatment: When an SBR completes a reaction cycle, the water decants to the UV treatment channel prior to discharge to the Mendenhall River. Sludge Process: Sludge from the SBRs is stored in the sludge storage tank. The sludge is dewatered in a belt filter press and trucked to the JDWWTP for incineration. INFLUENT PUMP STATION The wastewater flows into the influent pump station and passes through a grinder that breaks up solids and a sieve that catches rags. A rag screw removes the rags from the flow upstream of the wet well. Influent pumps lift the flow into centrifugal tea cups, which separates grit from the flow; the grit drops into a grit snail clarifier where it is dewatered. The wastewater flows to a distribution box that distributes it the SBRs. Analysis There are five influent pumps of equal capacity. They operate in sequence, typically with one pump capable of handling the flow, except for an average of one hour per day when two pumps operate. During periods of low flow, the lead pump cycles on and off with influent well water elevation. Variable speed pumps would be able to operate based on actual flow, saving energy and demand charges. SEQUENCING BATCH REACTORS There are eight SBR tanks where treatment occurs. The reaction process consists of aeration by air blowers and jet pumps and settling periods. Upon completion of the react cycle, the water decants to the UV treatment. Analysis A consultant is working with plant operators to optimize the treatment process. City and Borough of Juneau 33 Mendenhall WWTP Energy Audit

36 UV TREATMENT The treated water flows through a channel where it is treated with UV radiation. Analysis The UV system consists of three banks of UV lights. The system is sized so that two banks are able to treat the water with the third as backup. Turning off one bank will reduce energy consumption. If the decant flow was lowered so decanting occurs nearly continuously and lower flow rates, one bank may be sufficient to disinfect the effluent. A recirculating pump maintains the water level over the lamps when there is no flow. This pump operates because the weir gate that maintains the water elevation is leaking. Repairing the gate would reduce pump operation. SLUDGE TREATMENT A sludge tank aerates the sludge with an air blower and jet pump. The sludge transfers via a sludge grinder to the belt filter press for dewatering into a dry cake. The cake is trucked to the JDWWTP for incineration. Analysis The amount of sludge has increased in recent years from 500 to 800 dry metric tons per year. The increase is due to operational changes in 2005 that included taking the centrifuge and thickened sludge tank out of service. A review of the changes is warranted in consideration of the increased sludge production. City and Borough of Juneau 34 Mendenhall WWTP Energy Audit

37 MOTORS Table 4-1: Motors Service Horsepower Efficiency NEMA Premium Remarks Influent Pump Station Influent Pumps P1I-P5I 50 n/a 94.1 Integral with pump Auger Monster Less efficient Rag Screw Less efficient SBR Basins Blowers Jet Pumps P1J-P8J 36 n/a 94.1 Integral with pump Sludge Pumps P1S-P8J 16 n/a 92.4 Integral with pump Sludge Tank Blower Less efficient Secondary Grinder Less efficient Decant Pumps P1WS-P2WS 5 n/a 89.5 Integral with pump Transfer Pumps P3WS-P4WS Less efficient Transfer Pump P5WS Less efficient UV Treatment Recirculation Pumps Other Control Air Compressor Less efficient NPW Pump North Less efficient NPW Pump South Less efficient NPW Booster Pump Less efficient NPW Air Compressor Less efficient NPW Chlorinator Less efficient 1. New motor efficiency is based on NEMA Premium MG-1 efficiency motors. 2. No motor data available; motor efficiency assumed. Analysis Many of the motors are operated a significant number of hours each year to warrant replacement with a NEMA Premium motor. Some specialized service motors may not be available as NEMA Premium. City and Borough of Juneau 35 Mendenhall WWTP Energy Audit

38 This page intentionally left blank City and Borough of Juneau 36 Mendenhall WWTP Energy Audit

39 Section 5 Energy Conservation Opportunities Behavioral or Operational Energy Conservation Opportunities Top priority should be given to the following behavioral or operational ECOs that require minimal investment and offer immediate savings. The ECOs are listed from highest to lowest priority. ECO-1: Reduce Blower Room Temperature Purpose: The temperature in the blower room was 68 F on the day of the energy audit. Each blower enclosure has a cooling fan that circulates cooling air when the enclosure temperature exceeds 65 F. The temperature in the blower room causes the cooling fans to operate, even when the blower is off. Reducing the blower room temperature will minimize blower cooling fan energy and save heating energy. Scope: Turn down the setpoint in the SBR Building blower room. Recommendation: This ECO is recommended without additional analysis. ECO-2: Reduce Heating Setpoints Purpose: The temperature in many of the intermittently occupied rooms was F, which is much higher than needed to control humidity and provide thermal comfort. Reducing the temperature will save heating energy. Scope: Reduce the temperature of all intermittently occupied rooms. Recommendation: This ECO is recommended without additional analysis. ECO-3: Turn Off Unneeded Lighting Purpose: Throughout the plant, the lighting in some rooms is left on when rooms are not occupied. Turning off lighting will reduce energy use. Scope: Turn off lighting in unoccupied rooms. Recommendation: This ECO is recommended without additional analysis. ECO-4: Reduce Unoccupied Room Temperatures Purpose: The building temperature is constant even though the building is unoccupied during nights and weekends. Setting back the temperature during this time will reduce heating energy by 10-15%. Scope: Use a night setback control to turn down the temperature at night and restore the occupied temperature prior to building occupancy each day. This ECO is applicable to all buildings. Recommendation: This ECO is recommended without additional analysis. City and Borough of Juneau 37 Mendenhall WWTP Energy Audit

40 ECO-5: Review Sludge Treatment Process Purpose: The sludge treatment process changed in 2005, resulting in a 60% increase in the number of dry tons incinerated at the JDWWTP. A review of incinerator fuel oil records for the incinerator show that fuel oil consumption increased by 7,000 gallons, or 8%. Scope: Review the change in sludge treatment process and determine if the increase in fuel oil consumption is reasonable. Recommendation: This ECO is recommended without additional analysis. ECO-6: Optimize SBR Blower Operation Purpose: The SBR blowers are currently being modulated on a times sequence. Optimizing blower operation with dissolve oxygen control is likely to reduce blower airflow and save energy. Scope: Optimize blower operations by using DO control to vary the blower airflow rate. Analysis: It is not possible to estimate the extent that DO control will reduce blower airflow. If DO control reduces blower airflow by 10%, this ECO will annually reduce electric use by 24,000 kwh, and energy costs by $1,500. If DO control reduces blower airflow by 20%, this ECO will annually reduce electric use by 72,000 kwh, and energy costs by $4,600. Blower Output Construction Maintenance Energy Total Life Cycle Cost 10% Reduction $1,000 $0 ($28,600) ($27,700) 20% Reduction $1,000 $0 ($84,600) ($83,700) Note: Negative numbers, in parenthesis, represent savings. Recommendation: This ECO is recommended. ECO-7: Discontinue Lube Oil Building Heat Purpose: The Lube Oil Building is a thermally inefficient structure that is heated to store lubricants. If the lubricants were stored in another heated building, the Lube Oil Building could be unheated. Scope: Move the materials that require heat to another building and turn off the heat in the Lube Oil Building. Recommendation: This ECO is recommended without additional analysis. ECO-8: Install Interlocks on Overhead Door with Heaters Purpose: A considerable amount of heat escapes when overhead doors are open. Interlocking the heaters so they turn off while the doors are open will reduce the heat loss, especially on occasions where the doors are left open for long periods. Scope: Interlock the heaters with overhead doors so the heaters are off when the doors are open. This ECO is applicable to the SBR Building, ABF Plant, UV Building, Tanker Truck Building, and Lube Oil Building. Recommendation: This ECO is recommended without analysis. Interlocking overhead doors is good practice. City and Borough of Juneau 38 Mendenhall WWTP Energy Audit

41 ECO-9: Install SBR Building Main Entrance Heater Thermostat Purpose: The cabinet unit heater in the main entrance of the SBR Building does not have a thermostat to control the heat output. It supplies heat continuously during the heating season, but is turned off the rest of the year. Installing thermostatic control will limit the heat output. Scope: Install a thermostat and control valve to modulate the heat output of the cabinet unit heater. Recommendation: This ECO is recommended without additional analysis. Thermostatic control of the heater is good practice. ECO-10: Convert HVAC Systems to DDC Controls Purpose: The automatic control systems in the SBR Building are not providing adequate control. Many thermostats are turned fully up or down, a sign of a loss of control. The building s fuel consumption is high due to poor control strategies and lack of good thermal control. Consideration should also be given in a plant-wide DDC control system that will give maintenance personnel a central interface for monitoring the facilities. Scope: Convert the facility to a central DC control system. Estimated cost for the SBR Building is $310,000 and $430,000 for the entire facility. Develop optimized control strategies that incorporate the following: Optimal Operating Schedules Reducing Outside Air Flow using Humidity Monitoring Scheduled Ventilation Control Ventilation Supply Air Reset Control HVAC Occupancy Sensor Control Temperature Setback Recommendation: This ECO is recommended without additional analysis. ECO-11: Insulate Heating Piping Purpose: Insulating heating piping decreases heat loss and has a short payback. Scope: Add pipe insulation to the heating piping in the ABF Plant boiler room and the Tanker Truck Garage. Recommendation: This ECO is recommended without additional analysis. ECO-12: Replace ABF Boiler Operating Thermostat Purpose: Boilers are more efficient if they operate for long operating cycles and long off cycles. The ABF boiler efficiency can be improved by increasing the operating thermostat differential and by installing a modulating burner. The existing burner is not modulating and the control is operating the boiler on a 10 F differential. A new operating thermostat with a larger differential is needed. Scope: Install a modulating burner and a new boiler controller and set the operating range from F. Recommendation: This ECO is recommended without additional analysis. City and Borough of Juneau 39 Mendenhall WWTP Energy Audit

42 ECO-13: Adjust Disinfection Building Backdraft Dampers Purpose: The Disinfection Building has backdraft dampers for the exhaust fans and makeup air louvers that do not seal tightly when the fan is off. Adjusting the dampers so they seal tightly will reduce infiltration. Scope: Adjust the Disinfection Building backdraft dampers for the exhaust fans and makeup air louvers so they seal tightly when the fan is off. Recommendation: This ECO is recommended without additional analysis. ECO-14: Seal ABF Plant Exhaust Louvers and Ducts Purpose: The ABF Plant has numerous wall and roof penetrations for exhaust fans that are no longer in use. The unsealed penetrations allow heated air to escape to outdoors. Scope: Seal the wall and roof duct penetrations in the ABF Plant. Recommendation: This ECO is recommended without additional analysis. ECO-15: Evaluate Feasibility of Eliminating the ABF Plant Boiler Purpose: The SBR Boilers supply the SBR Building, Tanker Truck Building, and Lube Oil Building. The ABF Plant Boiler supplies the ABF Plant and Collections Building. By implementing many of the ECOs that reduce heating loads, the SBR boilers should have sufficient capacity to supply the entire facility. Scope: Connect the ABF Plant and Collections Building heating loads to the SBR Building boilers. Analysis: This ECO is only feasible if ECOs once ECOs that reduce heating loads are implemented. An analysis of the feasibility of supplying all loads by the SBR boilers is beyond the scope of this energy audit. Recommendation: Aggressive implementation of heating ECOs is recommended to improve the feasibility of this ECO. ECO-16: Turn Off SBR Building Water Cooler Purpose: The SBR Building has a drinking fountain with a cooling unit. Juneau s water supply is sufficiently cold enough that mechanical chilling is not needed. Turning off the cooler will reduce energy use. Scope: Turn off the water cooler. Recommendation: This ECO is recommended without additional analysis. ECO-17: Reduce SBR Building Air Compressor Pressure Purpose: The air compressor maintains the storage tank at sufficient pressure for the influent control valves. The valves will soon be replaced with lower pressure actuators. The air compressor pressure should be turned down once the actuators are replaced to save energy. Scope: Reduce the operating pressure of the air compressor when the influent valves are replaced. Recommendation: This ECO is recommended without additional analysis. City and Borough of Juneau 40 Mendenhall WWTP Energy Audit

43 ECO-18: Insulate Collections Building Hot Water Tanks Purpose: The hot water tank in the Collections Building is located in a cold room that increases tank heat loss. Wrapping the tank in an insulating blanket will decrease heat loss. Scope: Wrap the hot water heater in an insulating blanket. Recommendation: This ECO is recommended without additional analysis. ECO-19: Reduce SBR Building HW Temperature Purpose: The hot water tank supplies 130 F hot water to the fixtures. Reducing the setpoint to 120 F will reduce tank heat loss and piping heat loss and minimize scalding potential. Scope: Reduce the hot water heater setpoint to 120 F. Recommendation: This ECO is recommended without additional analysis. ECO-20: Install Lighting Occupancy Sensor Control Purpose: Occupancy sensors automatically turn off lighting in unoccupied rooms, saving energy. They are proven energy saving devices. Scope: Install occupancy sensors to control lighting in offices, toilet rooms, laboratory, etc. Recommendation: This ECO is recommended without additional analysis. ECO-21: Adjust and Monitor Exterior Lighting Photocells Purpose: Several exterior light fixtures remain on during daylight hours. Adjusting or replacing the internal photocell on each fixture so it turns off during daytime will save lighting energy. Scope: Adjust the exterior lighting photocells so the lamps are off during the day. This ECO is applicable to the UV Building. Recommendation: This ECO is recommended without additional analysis. ECO-22: Turn Off Lab Dryer and Furnace Purpose: The lab dryer and furnace are kept continuously hot even though they are only used during normal Monday to Friday work hours. Turning them off overnight and on weekends will save energy. Scope: Turn off the dryer and furnace overnight and on weekends. Recommendation: This ECO is recommended without additional analysis. ECO-23: Turn Off Idle Computers Purpose: Computers and peripheral equipment is often left on continuously. Turning them off during non-working hours will save energy. Scope: Turn off computers and peripheral equipment during non-working hours. Recommendation: This ECO is recommended without additional analysis. City and Borough of Juneau 41 Mendenhall WWTP Energy Audit

44 ECO-24: Insulate SBR Building Emergency Generator Ductwork Purpose: The ductwork connected to the generator discharge is uninsulated, increasing heat loss through the ductwork to the outdoors. Insulating the ductwork will reduce heat loss. Scope: Insulate the generator exhaust ductwork. Recommendation: This ECO is recommended without additional analysis. ECO-25: Install Water-Conserving Aerators and Shower Heads Purpose: The plumbing fixtures do not have water-conserving aerators and shower heads. Installing water-conserving aerators and shower head will reduce hot water consumption. Scope: Install water-conserving aerators and shower heads. Recommendation: This ECO is recommended without additional analysis. ECO-26: Install Automatic Controls for EF-105A/B/C Purpose: Exhaust Fans EF-105A/B/C supply the toilet rooms and are controlled by wall switches. Automatic control of the fans will ensure they only operate during occupied periods. Scope: Provide scheduled automatic control of Exhaust Fans EF-105A/B/C. Recommendation: This ECO is recommended without additional analysis. ECO-27: Test, Adjust, and Balance HVAC Systems Purpose: Mechanical systems are dynamic systems where operating parameters such as air balancing, water balancing can change over time. Observations by building occupants and operators indicate that the systems are no longer balanced. Scope: Test, adjust, and balance the mechanical systems. Recommendation: This ECO is recommended without additional analysis. ECO-28: Retrocommission SBR Building HVAC Systems Purpose: The commissioning process provides verification that the building systems operate as intended. Reportedly, the SBR Building systems were not properly commissioned as there were problems from the beginning. Retrocommissioning the system will ensure they are operating properly and as efficiently as possible. Scope: Retrocommission the HVAC systems. Recommendation: This ECO is recommended without additional analysis. ECO-29: Weather-strip Exterior Doors Purpose: The weather-stripping on many of the doors is poor or does not exist. Adding weatherstripping will reduce heat loss and minimize infiltration of damp air into the building. Scope: Replace or add door weather-stripping. This ECO is applicable to nearly all doors. Recommendation: This ECO is recommended without additional analysis. City and Borough of Juneau 42 Mendenhall WWTP Energy Audit

45 High Priority Energy Conservation Opportunities High priority ECOs provide a high life cycle savings for the relative investment. The ECOs are listed from highest to lowest priority. ECO-30: Turn off SBR Lag Boiler Purpose: Hot boilers have jacket, standby, and cycling losses of 1-3% of their input rating. The losses can be 100% of the input energy if the boiler is not supplying heat to the building. Turning off unneeded boilers will improve the seasonal efficiency of the heating pant. Scope: Turn off the SBR lag boiler from March to November when there is no risk of freezing the building if the lead boiler fails. Analysis: This ECO will annually reduce fuel oil use by 2,880 gallons, and energy costs by $5,500. Construction Maintenance Energy Total Life Cycle Cost $200 $9,300 ($155,100) ($145,600) Note: Negative numbers, in parenthesis, represent savings. Recommendation: This ECO is recommended. ECO-31: Turn off Boilers During Summer Purpose: Boilers of the size in the SBR and ABF Buildings have jacket, standby, and cycling losses of 1% of their input rating. The losses can be 100% of the input energy if the boiler is not supplying heat to the building. Turning off boilers will improve the seasonal efficiency of the heating plant. Scope: Turn off the SBR and ABF boilers when heat is not needed from June 1 to September 1. Analysis: This ECO will annually reduce fuel oil use by 1,800 gallons, and energy costs by $3,400. Construction Maintenance Energy Total Life Cycle Cost $200 $13,900 ($97,000) ($82,900) Note: Negative numbers, in parenthesis, represent savings. Recommendation: This ECO is recommended. City and Borough of Juneau 43 Mendenhall WWTP Energy Audit

46 ECO-32: Reduce UV Output to Two Banks Purpose: The UV system has three banks of lamps that operate continuously. The system is sized so two banks are capable of providing sufficient disinfection at current decanting flow rates. If the decanting flow rate is reduced, resulting in a more continuous effluent flow rate, one bank may be sufficient. Either operation will result in energy savings. Scope: Reduce UV system output to two banks or reduce the decant flow and reduce to one bank. Analysis: Trojan UV states that no depreciation in lamp life will occur as long as the lamp cycles are limited to three per day. The proposed strategy is daily operation of each lamp to limit the accumulation of growth. For one bank operation, each bank would operate steady for 8 hours per day. For two-bank operation, each bank would operate steady for 16 hours per day. Reducing UV output will also increase the service life of each lamp. If two banks are operated, this ECO will annually reduce electric use by 109,000 kwh, electric demand by 150 kw, and energy costs by $8,300. If decant flow rates are reduced so one bank is operated, this ECO will annually reduce electric use by 218,000 kwh, electric demand by 300 kw, and energy costs by $16,700. UV Output Construction Maintenance Energy Total Life Cycle Cost Two Banks $1,000 ($67,600) ($154,700) ($221,300) One Bank $1,900 ($135,200) ($309,400) ($442,700) Note: Negative numbers, in parenthesis, represent savings. Recommendation: This ECO is recommended. ECO-33: Repair SBR Building AHU-101/AHU-102 Heat Recovery Purpose: The heat recovery loop between AHU-101 and AHU-102 has been removed from service. Restoring the heat recovery will significantly reduce energy consumption. Scope: Return the AHU-101/102 heat recovery loop to operation. Analysis: This ECO will annually reduce fuel oil use by 9,900 gallons, and energy costs by $18,000. Construction Maintenance Energy Total Life Cycle Cost $2,500 $2,300 ($521,600) ($516,800) Note: Negative numbers, in parenthesis, represent savings. Recommendation: This ECO is recommended. City and Borough of Juneau 44 Mendenhall WWTP Energy Audit

47 ECO-34: Repair SBR Building AHU-103/104 Heat Recovery Purpose: The heat recovery loop between AHU-103 and AHU-104 has been removed from service. Restoring the heat recovery will significantly reduce energy consumption. Scope: Return the AHU-103/104 heat recovery loop to operation. Analysis: This ECO will annually reduce fuel oil use by 9,900 gallons, and energy costs by $18,000. Construction Maintenance Energy Total Life Cycle Cost $2,500 $2,300 ($521,600) ($516,800) Note: Negative numbers, in parenthesis, represent savings. Recommendation: This ECO is recommended. ECO-35: Install ABF Plant Boiler Room Heat Recovery Purpose: The ABF Plant boiler room is hot due to heat gain from the boiler. Install a fan to distribute the heat to adjacent spaces. Scope: Install a wall and fan to transfer the boiler heat to the ABF Plant. Analysis: This ECO will annually reduce fuel oil use by 1,100 gallons, and energy costs by $2,000. Construction Maintenance Energy Total Life Cycle Cost $2,500 $1,200 ($57,300) ($53,600) Note: Negative numbers, in parenthesis, represent savings. Recommendation: This ECO is recommended. ECO-36: Replace Clothes Washer Purpose: A top-loading washing machine is less-efficient and uses more water than a front-loading model. Replacing the washing machine with a front-loading model saves energy and hot water. Scope: Replace the clothes washer with a front-loading model. Analysis: This ECO will annually reduce electric use by 6,100 kwh and energy costs by $370. Recommendation: This ECO is recommended. Construction Maintenance Energy Total Life Cycle Cost $800 $0 ($6,800) ($6,000) Note: Negative numbers, in parenthesis, represent savings. City and Borough of Juneau 45 Mendenhall WWTP Energy Audit

48 ECO-37: Install SBR Building AHU-105 Heat Recovery System Purpose: AHU-105 supplies 12,450 cfm of ventilation air to the Blower Room. Adding a heat recovery loop that transfers heat from the exhaust air will save energy. Scope: Install a heat recovery coil in AHU-105. Return EF-101 to service and install a heat recovery coil in the inlet duct. Install a heat recovery loop between the two coils and provide controls. Analysis: This ECO will annually reduce fuel oil use by 7,000 gallons, and energy costs by $9,700. Construction Maintenance Energy Total Life Cycle Cost $51,500 $2,300 ($309,800) ($256,000) Note: Negative numbers, in parenthesis, represent savings. Recommendation: This ECO is recommended. ECO-38: Install Unit Heater Automatic Valves Purpose: The unit heater coil is kept continuously hot, even when heat is not required. Installing an automatic valve that shuts of heating supply flow when heat is not needed will reduce standby losses. Scope: Install automatic valves in the unit heater heating supply with thermostat control. This ECO is applicable to all buildings. Analysis: This ECO will annually reduce fuel oil use by 660 gallons, and energy costs by $1,300. Construction Maintenance Energy Total Life Cycle Cost $11,100 $0 ($69,300) ($58,200) Note: Negative numbers, in parenthesis, represent savings. Recommendation: This ECO is recommended. ECO-39: Replace HVAC Motors Purpose: Motor efficiencies have improved in recent years with the acceptance of the NEMA Premium MG-1 standard. Replacing less efficient motors with NEMA Premium motor will reduce energy and demand costs. Scope: Replace motors the following motors with NEMA Premium energy efficient motors: HWP- 101/102, HWP-103/104, HWP-111A/B, HWP-114A/B, AHU-101,, AHU-102, AHU-103, AHU-104, AHU-105,, AHU-107. Analysis: This ECO will annually reduce electric use by 28,000 kwh, electric demand by 39 kw, and energy costs by $2,100. Construction Maintenance Energy Total Life Cycle Cost $13,100 $0 ($39,400) ($26,300) Note: Negative numbers, in parenthesis, represent savings. Recommendation: This ECO is recommended. City and Borough of Juneau 46 Mendenhall WWTP Energy Audit

49 Medium Priority Energy Conservation Opportunities Medium priority ECOs provide life cycle energy savings that exceed the investment cost required to implement the change. These ECOs have a lower priority because the cost of implementation is high or the savings is minimal. ECO-40: Convert to Variable Speed Hydronic Pumping Purpose: The SBR Building hydronic heating system uses constant speed pumps to circulate heating water. These pumps consume nearly the same amount of energy year-round. Variable speed pumps allow pumping energy to decrease as heating loads decrease. The SBR Building boilers serve a large enough load that variable speed pumps can significantly reduce pumping costs. Scope: Replace the secondary constant speed pumps with one pair of variable speed pumps. Analysis: This ECO will annually reduce electric use by 45,000 kwh, electric demand by 45 kw, and energy costs by $3,300. Construction Maintenance Energy Total Life Cycle Cost $29,100 ($4,600) ($60,800) ($36,300) Note: Negative numbers, in parenthesis, represent savings. Recommendation: This ECO is recommended. ECO-41: Insulate Collections Building Walls Purpose: The walls in the Collections Building are significantly under-insulated. Adding insulation to the wall exterior and residing the building will reduce energy costs. Scope: Add insulation and metal cladding to the exterior of the Collections Building walls. Cover or provide access to some electrical conduits. Analysis: This ECO will, on an annual basis, reduce fuel oil use by 1,600 gallons, and energy costs by $3,000. Construction Maintenance Energy Total Life Cycle Cost $42,400 $0 ($84,000) ($41,600) Note: Negative numbers, in parenthesis, represent savings. Recommendation: This ECO is recommended. ECO-42: Install SBR Building MCC Room Heat Recovery Purpose: The electrical equipment in the MCC Room generates considerable amounts of heat. This heat is discharged outdoors by an exhaust fan. Modifying the system so that the warm air is supplied to adjacent rooms when they need heat or to an SBR Room will reduce energy use. Scope: Modify the MCC Room cooling system to supply the warm air to adjacent exterior rooms. Analysis: This ECO will annually reduce fuel oil use by 900 gallons, and energy costs by $1,800. Construction Maintenance Energy Total Life Cycle Cost $26,000 $2,300 ($49,700) ($21,400) Note: Negative numbers, in parenthesis, represent savings. Recommendation: This ECO is recommended. City and Borough of Juneau 47 Mendenhall WWTP Energy Audit

50 ECO-43: Replace Collections Building Windows Purpose: The Collections Building has inefficient single pane windows. Replacing the windows will save energy and improve occupant comfort. Scope: Replace the single pane windows in the collections building. Analysis: This ECO will, on an annual basis, reduce fuel oil use by 220 gallons, and energy costs by $400. Construction Maintenance Energy Total Life Cycle Cost $7,000 $0 ($11,700) ($4,700) Note: Negative numbers, in parenthesis, represent savings. Recommendation: This ECO is recommended. ECO-44: Replace Process Motors Purpose: Motor efficiencies have improved in recent years with the acceptance of the NEMA Premium MG-1 standard. Replacing less efficient motors with NEMA Premium motor will reduce energy and demand costs. Scope: Replace the following motors with NEMA Premium energy efficient motors: Auger Monster; Rag Screw; Secondary Grinder; Sludge Pump P5WS; NPW Pumps; NPW Booster; NPW Chlorinator. Analysis: This ECO will annually reduce electric use by 9,278 kwh, electric demand by 28 kw, and energy costs by $860. Construction Maintenance Energy Total Life Cycle Cost $10,000 $0 ($15,800) ($5,800) Note: Negative numbers, in parenthesis, represent savings. Recommendation: This ECO is recommended. ECO-45: Insulate Collections Building Roof Purpose: The Collections Building roof is significantly under insulated. Typically, adding insulation to a roof does not provide a life cycle savings. However, the roof is so under insulated that energy savings may offset the insulation cost. Scope: Add insulation and a new roof membrane to the Collections Building roof. Analysis: This ECO will, on an annual basis, reduce fuel oil use by 640 gallons, and energy costs by $1,200. Construction Maintenance Energy Total Life Cycle Cost $23,800 $0 ($34,700) ($10,900) Note: Negative numbers, in parenthesis, represent savings. Recommendation: This ECO is recommended. City and Borough of Juneau 48 Mendenhall WWTP Energy Audit

51 ECO-46: Upgrade SBR Building Lighting Purpose: The SBR Building has a few T12 lighting fixtures that have lower efficacy than newer technologies such as T8 and T5 lighting. Reballasting and relamping the fixtures with T8 lamps will save energy. Scope: Reballast and relamp existing fixtures with T8 lamps. Analysis: This ECO will annually reduce electric use by 980 kwh and energy costs by $60. Construction Maintenance Energy Total Life Cycle Cost $1,100 $0 ($1,600) ($500) Note: Negative numbers, in parenthesis, represent savings. Recommendation: This ECO is recommended. ECO-47: Replace Older Transformers Purpose: The step down transformers in the buildings have lower efficiencies than modern, energy efficient transformers. Replacing the transformers will save electricity. Scope: Replace older dry-type transformers with newer energy efficient models. This ECO is applicable to the SBR Building and UV Building. Analysis: This ECO will annually reduce electric use by 41,800 kwh, electric demand by 60 kw, and energy costs by $3,200. Construction Maintenance Energy Total Life Cycle Cost $48,300 $0 ($59,800) ($11,500) Note: Negative numbers, in parenthesis, represent savings. Recommendation: This ECO is recommended. Low Priority Energy Conservation Opportunities Low priority ECOs do not offer a life cycle energy savings and are not recommended. ECO-48: Replace Influent Pumps, Install VFDs Purpose: The influent pumps are the original pumps. Replacing the pumps with more efficient modern pumps will reduce energy costs. The influent pumps cycle on and off to maintain wet well levels. Variable speed operation would minimize energy and demand changes by matching the pump output to the influent flow rate. Scope: Replace the three influent pumps and install VFDs. Analysis: This ECO will annually reduce electric use by 28,000 kwh, electric demand by 378 kw, and energy costs by $48,000. Unfortunately, an investment in new pumps and VFDs does not provide a life cycle savings. Construction Maintenance Energy Total Life Cycle Cost $150,000 $0 ($101,700) $48,300 Note: Negative numbers, in parenthesis, represent savings. Recommendation: This ECO is not recommended. City and Borough of Juneau 49 Mendenhall WWTP Energy Audit

52 ECO-49: Install Boiler Daytanks Purpose: The fuel oil system that supplies the boilers consists of two buried fuel tanks with submersible fuel oil pumps. One pump operates continuously to supply fuel to the boilers. Installing boiler daytanks will allow the pumps to operate only a fraction of each day to refill the daytanks. Scope: Install a daytank and controls in the SBR Building and ABF Plant Boiler Room. Tie the daytank controls into the fuel pump starters to operate the lead fuel pump to fill a daytank. Analysis: This ECO will annually reduce electric use by 9,800 kwh, electric demand by 12 kw, and energy costs by $740. However, it does not provide a life cycle savings due to the cost of control wiring and interface with the fuel pump starters. Construction Maintenance Energy Total Life Cycle Cost $16,500 $4,600 ($13,600) $7,500 Note: Negative numbers, in parenthesis, represent savings. Recommendation: This ECO is not recommended. ECO-50: Replace Influent Pumps Purpose: The influent pumps are the original pumps. Replacing the pumps with more efficient modern pumps will reduce energy costs. Scope: Replace three influent pumps with more efficient pumps. Analysis: The water-to-wire efficiency of the existing and proposed pumps is 63% and 69%, respectively. This ECO will annually reduce electric use by 25,000 kwh, electric demand by 41 kw, and energy costs by $2,000. Unfortunately, an investment in new pumps does not provide a life cycle savings. Construction Maintenance Energy Total Life Cycle Cost $112,500 $0 ($37,200) $75,300 Note: Negative numbers, in parenthesis, represent savings. Recommendation: This ECO is not recommended. ECO-51: SBR Building AHU-112/114 Heat Recovery Purpose: The heat recovery loop between AHU-112 and AHU-114 has been removed from service. The fans are currently used sparingly. If fan use increases in the future, restoring the heat recovery will reduce energy consumption. Scope: If the operating hours of AHU-112/114 increase significantly in the future, return the heat recovery loop to operation. Recommendation: This ECO is not recommended unless the number of AHU-112/114 operating hours is increased. City and Borough of Juneau 50 Mendenhall WWTP Energy Audit

53 ECO-52: Replace Exterior Doors Purpose: Many of the metal doors and frames are not thermally broken. This allows a direct conducive path of heat to the outside, significantly reducing the door R-value. Replacing the doors and frames with thermally broken units will reduce heat loss. Scope: Replace non-thermally broken doors and frames. This ECO is applicable to nearly all doors. Recommendation: This ECO is not recommended. Past analysis has shown that energy savings will not offset the costs of replacing the doors and frames. ECO-53: Install Collections Building Arctic Entrance Purpose: Arctic entrances save energy by reducing infiltration when exterior doors are opened. They offer the greatest savings on heavily used doors. The main entrance and side entrance at the Collections Buildings is heavily used and worthy of having an arctic entrance. Scope: Install an arctic entrance at the main entrance of the Collection s Building Analysis: An arctic entrance requires sufficient length between the inner and outer doors so one shuts before the other opens. The building is space constrained indoors and on the site so that this distance is not readily available. Recommendation: This ECO is not recommended. City and Borough of Juneau 51 Mendenhall WWTP Energy Audit

54 This page intentionally left blank City and Borough of Juneau 52 Mendenhall WWTP Energy Audit

55 Appendix A Energy Use Data City and Borough of Juneau Mendenhall WWTP Energy Audit

56 This page intentionally left blank City and Borough of Juneau Mendenhall WWTP Energy Audit

57 25200 Amalga Harbor Road Tel/Fax: Juneau, Alaska Electric Use Data March 27, 2009 Mendenhall Wastewater Treatment Plant ELECTRIC RATE AEL&P Electric Rate 34 On-Peak Nov-May Off-peak Jun-Oct Electricity ($ / kwh ) Demand ( $ / kw ) Customer Charge ( $ / mo ) Power Cost Adjustment ( $ / kwh ) Regulatory Cost Charge ( $ / kwh ) Sales Tax ( % ) 0.0% 0.0% ELECTRICAL CONSUMPTION AND DEMAND Month kwh kw kwh kw kwh kw kwh kw Average Jan 319, , , , ,081,660 Feb 300, , , , ,085,020 Mar 305, , , , ,033,500 Apr 325, , , , ,046,140 May 280, , , , ,860 Jun 293, , , , ,006,440 Jul 328, , , , ,028,800 Aug 303, , , , ,084,260 Sep 308, , , , ,068,160 Oct 339, , , , ,096,360 Nov 270, , , , ,102,080 Dec 263, , , , ,071,500 Total 3,638,600 3,093,100 3,075,920 2,876,160 3,170,945 Average 303, , , , ,245 Load Factor 70.7% 67.7% 71.9% 68.2% 520 ELECTRIC BILLING DETAILS Electrical costs are based on the current electric rates Month Energy Demand Cust & Tax Total Energy Demand Cust & Tax Total % Change Jan 16,313 6, ,650 14,275 5, , % Feb 15,904 5, ,295 17,483 6, , % Mar 15,755 4, ,709 14,650 5, , % Apr 14,067 5, ,609 14,946 5, , % May 16,575 5, ,208 12,310 5, , % Jun 14,964 3, ,496 13,061 3, , % Jul 12,817 3, ,268 12,873 3, , % Aug 16,323 3, ,892 14,392 3, , % Sep 13,736 3, ,363 13,839 3, , % Oct 14,983 3, ,080 13,389 3, , % Nov 18,233 6, ,639 16,298 5, , % Dec 16,259 5, ,354 16,368 6, , % Total $ 185,929 $ 57,443 $ 1,191 $ 244,562 $ 173,883 $ 56,985 $ 1,191 $ 232, % Average $ 15,494 $ 4,787 $ 99 $ 20,380 $ 14,490 $ 4,749 $ 99 $ 19, % Cost ($/kwh) % 25% 1% % Page 1

58 25200 Amalga Harbor Road Tel/Fax: Juneau, Alaska Yearly Comparison March 27, 2009 Mendenhall Wastewater Treatment Plant 400,000 Energy Use Comparison 350, ,000 kwh 250, , , ,000 50, Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 700 Energy Demand Comparison kw Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Page 2

59 25200 Amalga Harbor Road Tel/Fax: Juneau, Alaska Annual Comparison March 27, 2009 Mendenhall Wastewater Treatment Plant Energy Cost Breakdown $ 25,000 $ 20,000 $ 15,000 $ 10,000 $ 5,000 $ 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Energy (kwh) Costs Demand (kw) Costs Customer Charge and Taxes Energy and Demand Comparison 300, , Energy Use (kwh) 200, , , Demand (kw) 50,000 Energy Demand Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 0 Page 3