Biomass CHP Serves Ohio Veterans Well
Sure, it was an award-winning first biomass design for the VA. And yes, it’s a big efficiency improvement.
The installation of the Department of Veterans Affairs’ (VA) first operational biomass combined heat and power (CHP) plant at the Chillicothe, OH, VA Medical Center (VAMC) was among only 14 federal projects in the nation (and only 25 individuals, groups, and agencies overall) to win a 2013 Federal Energy and Water Management Award in recognition of its significant achievements in fiscal year (FY) 2012. Funded in part by the American Reinvestment and Recovery Act, the biomass facility is part of a $25.5-million design-build project to replace an aging boiler plant and steam distribution system with a new high-efficiency natural gas/oil-fired boiler plant. The project is a component of an extensive 40-yr plan to implement sustainable, cost-effective practices at the Chillicothe VAMC.
Over the course of the project, the design-build team collaborated on several mechanical, electrical and plumbing (MEP) design alternatives with favorable impacts on project costs, schedule, and functionality. These alternatives saved a total of more than $580,000 on various components of the project, allowing for reinvestment of project capital into higher-value equipment, construction of an enclosed facility for the emergency generator, and the addition of a 125-ton absorption chiller to one of the buildings on the campus, which uses the steam generated during the summer to increase energy efficiency.
Getting The Team Together
The project was managed by the U.S. Army Corps of Engineers (USACE) on behalf of the VA. It was awarded in September 2009 as a design-build contract to Bristol Design Build Services, LLC, in Anchorage, AK, a member of the Bristol Alliance of Companies, which are wholly owned subsidiaries of the Bristol Bay Native Corporation, a regional Alaska Native Corporation. Woolpert Engineering in Cincinnati was selected to provide the architectural, structural, mechanical, electrical, plumbing, and fire protection designs.
DeBra-Kuempel, an EMCOR Company, was selected to provide and install the mechanical, electrical, plumbing, HVAC, controls, fire sprinkler, communications, data, and alarm systems. DeBra-Kuempel actively participated in the equipment selection, pressurized oil delivery system design, process piping layout (including 3-D modeling), electrical design, plumbing layout, and controls design. The company also collaborated with S.A. Comunale, Inc., also an EMCOR company, and an industry leader in design, installation, inspection, and service of fire sprinkler and alarm systems. This project was notable for the extraordinary level of collaboration among the members of the project team — in particular, the openness to suggestions and evident value placed on the unique skill sets contributed by each discipline.
A Closer Look at the MEP Components
Comprising a 600-hp Wellons wood chip-burning biomass boiler and a 400-kW steam induction turbine generator, the award-winning biomass facility was put into service in May 2012. The biomass facility saved 10 million Btus of natural gas and more than $170,000 in fuel costs during the remainder of FY 2012 as compared with FY 2011, and it generated 576,000 kWh of electricity. In 2013, the biomass facility was maintained as the primary steam source for the VAMC, with the anticipation of increased savings in FY 2013 over FY 2012. Moreover, with the designer’s incorporation of an electrostatic precipitator, the facility exceeds Ohio Environmental Protection Agency standards for airborne particle removal.
The new natural gas/oil-fired boiler plant is designed to supply year-round steam to the VAMC, which comprises more than 30 buildings totaling approximately one million sq ft of space. The new plant includes three 700-hp Cleaver Brooks boilers, new gas service, two 30,000-gal underground fuel oil storage tanks with a pressurized oil delivery system as backup to the primary natural gas-fired process, new electrical service and distribution, a new reverse osmosis water system, and an Automated Logic control system integrated with the boiler-supplied controls.
Biomass Proves Feasible
Design-build projects are by their nature challenging in every respect, including design and installation of the MEP systems. This project was no exception. In particular, in April 2010, the USACE asked the Bristol design-build team to price a change order to add a new building to house a biomass facility equipped to their specifications at the Chillicothe VAMC.
The integration of this facility into this project came about as part of the VA’s renewable energy initiative. In 2008, the VA had screened its major facilities for the potential to use solar, wind, geothermal, and biomass energy, and the Chillicothe VAMC was identified as a potential site for biomass energy.
In November 2009, the U.S. Department of Agriculture Forest Service Wood Education and Resource Center (WERC) Technical Assistance Team was asked to provide support for the VAMC woody biomass project, including a final engineering and financial feasibility analysis. The WERC team concluded that a biomass CHP system had the potential to replace 89% of natural gas fuel usage and generate 1.6 million kWh of electricity a year. The WERC team presented their findings to the Bristol team and owner at the 50% design meeting for the new natural gas/oil-fired boiler plant. Based on these findings, the VAMC and USACE decided to proceed with the biomass facility at the Chillicothe site.
Meanwhile, construction had begun as scheduled in August 2010 on phase one of the project — the gas/oil-fired boiler plant — while the design of the biomass plant was completed. This allowed for a seamless transition of effort from one construction phase to the next. The continuity of the skilled craft workforce on both phases allowed commissioning to proceed on phase one while construction began on the biomass plant in December 2010.
Maintaining Service Continuity and Flexibility
The design-build team collaborated on several MEP design alternatives with favorable impacts on project costs, schedule, and functionality. For example, during phase one, Woolpert and DeBra-Kuempel collaborated on the design of new valving assemblies to enable the old boiler plant to be brought back on line at any time during construction of the new natural gas/oil-fired plant, if necessary, with a simple valve change-over. This allowed for continuity while facilitating the final decommissioning of the original plant on completion of the biomass installation. The existing boiler plant fed the VAMC campus via two utility trenches leaving the plant — one to the west and one to the north. The new boiler plant was under construction north of the existing boiler plant.
The new valving assemblies included an isolation valve in the valve pit at the tie-in to the north loop (read more about the north loop, below), which allowed the new plant to feed the north loop and back-feed the west loop through the existing boiler plant. Rather than conventional gate-valves, the design team decided on the use of high-performance triple-offset butterfly valves to optimize the steam distribution system while using less space in the valve pit. Another valving assembly was installed in a tight space at the southwest corner of the existing boiler plant to tie the new plant into the west loop.
Following one brief shutdown to install the valves, plant operators were able to seamlessly transition from generating and feeding steam to the entire campus either from the old or new boiler plant. These valving arrangements provided the VAMC with the flexibility either to tear down or repurpose the building.
Here is just one instance in which DeBra-Kuempel’s in-house CAD capabilities facilitated installation throughout the project. As the Bristol design team progressed from conceptual design through development of engineering and construction documents, DeBra-Kuempel’s CAD designer built a 3-D model of the piping systems and incorporated changes as they occurred. This allowed the team to identify and resolve potential conflicts among systems prior to construction, thereby streamlining the installation process. As a result, there were no adverse interactions requiring rework, which is further evidence of the value of this up-front investment.
The new natural gas/oil-fired boiler plant was completed and commissioned to VA standards in February 2012. The VAMC elected to decommission and demolish the existing boiler equipment to repurpose the old boiler plant building as a fire station.
Reconditioning North Utility Trench Generates Savings
Over the course of the project, DeBra-Kuempel offered several MEP design alternatives to the Bristol team, VA, and USACE, which contributed to capital and time savings and enhanced the functionality of the MEP systems. For example, the project design initially called for construction of a new utility trench running north from the existing boiler plant to the new plant, as it was believed that the existing utility trench had reached the end of its useful life. DeBra-Kuempel performed a site survey of existing conditions, including density checks of the existing piping. Among their findings, the team noted that some sections of the old condensate system, which had been installed approximately 20 years before, were composed of type K copper. This type of piping exceeded the specifications for condensate piping in the new utility tunnel.
Based on the results of this site survey, DeBra-Kuempel proposed an alternative to construction of a new utility tunnel: to fully recondition the existing north tunnel by replacing concrete lids, installing waterproof membrane material, installing new galvanized hangers and supports, and replacing piping based on density results. The design team and owner accepted this alternative. Existing asbestos insulation was abated from the existing steam and condensate lines, pipes were cleaned, new supports were installed, pipe was re-insulated, and new seals were installed. This alternative saved an estimated $400,000 on project costs and weeks on the schedule.
The team also collaborated on constructability of the utility tunnel and on the anchoring and support systems for expansion and contraction of the high-pressure steam lines in the biomass facility.
An Improved Backup Fuel Oil System
The VA requires a dual fuel natural gas/oil-fired boiler system to assure the reliability of the boiler plants in its facility inventory. The VA’s specifications for the oil delivery system did not allow submersible pumps to be used in the oil tanks; however, the VA accepted DeBra-Kuempel’s proposal of a variance for a cleaner, more cost-effective, efficient, and maintainable system. The design comprises a submersible pump system located outside the building and a pressurized oil loop with back-pressure control to eliminate the need for a secondary 600-gal storage system inside the boiler room. This system yielded estimated savings to the project of $80,000 and freed up approximately 100 sq ft of floor space in this one-level, 8,000-sq-ft boiler plant.
In addition, the VA was looking for a plan to pump out and dispose of the oil from the existing underground oil storage tanks before installation of the two new tanks. DeBra-Kuempel contracted for pumping out, filtration, and reconditioning the oil for use in the new tanks. Approximately 40,000 gal of oil were salvaged, saving approximately $100,000 (i.e., 70%) on the costs of oil disposal and resupply.
These are just a few examples of the effective collaboration and teamwork among the members of the design-build team on this award-winning project. The savings that accrued from these collaborative efforts allowed for reinvestment of project capital to provide added value for the VAMC. Moreover, the project was completed on time, within the budget, and with no contractor-initiated change orders.
With the completion of commissioning in June 2012, the VAMC biomass facility has become a model of success for the VA system’s renewable energy initiative and emblematic of the capabilities and dedication of everyone who contributed to the successful execution of this challenging project