Strength In Numbers
Beginning in 2001, James Naylor, P.E., special projects manager at Marine Corps Base (MCB) Quantico, led the charge to modernize the base's ailing infrastructure with efficient, decentralized heating plants. The poor condition of the steam and condensate piping resulted in substantial energy loss, building damage, and a mounting deferred-maintenance liability.
Naylor opted for an energy savings performance contract (ESPC) strategy and designated the energy services company (ESCO) Select Energy Services, Inc. (SESI), to implement a program for installation and maintenance of new boilers and other heating equipment within various buildings.
Within three years, new heating plants serving 125 buildings (3.5 million sq ft) had been installed and placed in operation. The central steam system was decommissioned, and measurement and verification (M&V) confirms that the project saves more than $3.9 million/yr in costs for utilities and O&M. Taking utility cost escalation into account, the total savings over the life of the project will exceed $120 million.
The total ESPC cost, which MCB Quantico repays out of its utility budget as annual savings, is $31.5 million and includes construction as well as O&M over the 23-year contract term.
Pre-Implementation Facility ConditionsAs the USMC's premier enlisted- and officer-training academy in the Northeast, MCB Quantico occupies a 60,000-acre site in Quantico, VA that reaches into three counties. It hosts a number of facilities including Officer Candidates School, Marine Corps University, Marine Corps Air Facility, target ranges, and recreational areas. Buildings date back as far as 1919, with many listed as historically significant. Among the various building uses are housing, administration, education, multi-purpose, library, dining, recreation, storage, maintenance, and medical care.
The existing central steam plant originally burned coal but was later converted to use natural gas, with No. 2 fuel oil for backup. It was capable of producing 260,000 lbs/hr of steam at its distribution pressure of 125 psig.
The aging steam and condensate site-distribution piping developed significant leakage through connections, steam traps, and breaks, resulting in less than 20% of the supplied steam returning to the central plant as condensate. Many of these losses were evidenced by heavy steam plumes discharging continuously from manholes and vents. Conduction heat losses, inherent in any site steam-distribution system, worsened from damage, deterioration, and waterlogged pipe insulation.
The central plant used an annual average of 500,000 MBtu of natural gas and fuel oil, at a cost of $2.25 million. The steam and condensate losses resulted in a high makeup rate for water and associated costs for chemical treatment. In addition, the leaking steam and condensate also raised issues over environmental liability.
The steam systems inside the various buildings had deteriorated as well due to poor water quality and limited maintenance resources. Leaks resulted in building moisture damage, mold growth, and employee health concerns. A full restoration of the heating infrastructure would have required major expenditures to replace not only site-distribution piping, but also building heat exchangers, pressure-reducing stations, condensate-return units, and piping. "It was estimated that a modernization program would have cost a total of at least $57 million over the next 23 years," said Robert Calloway, P.E., regional manager for SESI.
The site-distribution piping supplied steam to the buildings, where it was converted (through shell-and-tube heat exchangers) or used directly for various types of comfort, process, and domestic water heating systems. Comfort/process systems included heating-water (as part of two-pipe and four-pipe systems), low-pressure steam (up to 15 psig), medium-pressure steam (16 to 125 psig), and water-source heat pumps.
The ProgramThe boiler decentralization project was implemented through an ESPC, whereby SESI has turnkey responsibility for the project's development, design, financing, construction, commissioning, O&M, performance, and energy-savings assurance. This approach has many advantages to the traditional design/bid/build delivery method, including: 1) preservation of capital funds for non-energy-related projects; 2) upgrade of critical infrastructure; 3) acceleration of improvements through D-B, avoiding the government's lengthy funding cycle for capital projects; 4) assistance to agencies in meeting federally mandated energy reduction goals; and 5) placement of primary responsibility on SESI for successful operational and energy-reduction performance.
The major stages of the ESPC process are: feasibility/development, implementation (i.e., design and construction), and performance period. During feasibility/development, SESI performed measurements to establish baseline energy use and cost, proposed a detailed scope of work and price, and calculated projected savings. As part of this effort, the government and SESI also agreed on the specific responsibilities of each party and performance parameters.
Implementation: Design ChallengesThe heating plants for each building were conceptually designed to match the type and load of the existing distribution system (piping, pumps, terminal equipment, and other components). The new heating plants were connected into the "head end" of the existing distribution systems, which remained in use. The types of heating-plant equipment and system configurations implemented were standardized to the extent practical; however, variations were necessary in adapting to diverse heating loads, steam-pressure requirements, system configurations, and other specific physical conditions that existed throughout the site.
"Despite the outward cookie-cutter appearance of many buildings, no two were the same from a mechanical design standpoint," said Robert Leftwich, P.E., project engineer for SESI. "It was also a challenge to trace out the buildings' existing heating systems to ensure that the proposed modifications didn't ‘orphan' isolated end-use equipment."
Ultimately, 117 boilers were installed in 77 buildings. Where possible, boilers were located within existing mechanical rooms. In many cases, life-safety codes required construction of a separate boiler room. Where indoor space was not available, SESI constructed building additions or used outdoor hot water boilers. Plants with multiple boilers provided redundancy in housing, medical care, and mission-critical facilities.
Although reusing existing distribution systems minimized cost, it did require SESI handling their "baggage," including residual scale from aging piping and poor water quality. This was especially true for the steam-based distribution systems, which the central plant previously fed. An ongoing program of flushing, chemical treatment, and makeup water softening, has greatly improved conditions and reduced the risk of deterioration in the new boilers. Meters for boiler plant makeup water were installed during construction and later found to be beneficial in identifying and quantifying losses from the original building distribution systems. Repairs of leaks were then necessary to successfully manage water treatment.
Hot water BoilersHot water boiler plants were installed in 53 buildings. The models selected were high-efficiency Evolution-series boilers, manufactured by Thermal Solutions Products, with capacities ranging from 500 to 2,000 kBtuhr (thousand British thermal units per hour). Where possible, the boilers were direct-vented to minimize cost and aesthetic impact. The boilers were outfitted with circulating pumps in a primary/secondary configuration with the building distribution pumps (Figure 1). To optimize performance and energy savings, the boilers were staged to reset hot-water supply temperature based on outdoor-air temperature and automatically shutdown when the outdoor-air temperature exceeds 60°F.
Steam BoilersSectional boilers manufactured by Smith Cast Iron Boilers, ranging in size from 500 to 2,500 kBtuhr, were used in 18 buildings where terminal equipment required low-pressure steam.
Medium-pressure steam plants were installed in six locations for comfort and process heating in mess halls, a medical clinic, the wastewater treatment plant, and airfield structures (hangars and other buildings). Boilers included Scotch Marine and vertical fire-tube boilers manufactured by Cleaver Brooks and Hurst Boiler and Welding Company, ranging in size from 35 to 100 bhp.
MCB Quantico had their own long-term plans in place to decentralize heating for the airfield through various construction projects. For the immediate need, however, SESI installed a 500-bhp plant, the largest under this project, which was delivered as three preassembled sea containers. This approach gives the plant the mobility to be used elsewhere when the airfield's decentralization is complete.
To optimize savings and steam boiler performance, the project also included a comprehensive survey of the remaining steam traps to identify and replace failed units. Venturi-style traps were installed because they require minimal maintenance and offered the best life-cycle value for this application. Another energy-saving feature was control to reduce output pressure in selected medium-pressure steam plants during unoccupied hours.
Unitary Heating EquipmentOther comfort-heating equipment installed included a variety of gas-fired infrared heaters, unit heaters, rooftop units, duct furnaces, makeup air units, and electric heat pumps.
Domestic Water HeatersForty-eight domestic water heaters were also installed. They ranged from 4.5-kW, electric units (manufactured by State Water Heaters) to 2,800-kBtuhr gas-fired units, with 400-gal storage tanks (manufactured by PVI Industries). In the bachelors' enlisted quarters (BEQs), the heaters fed existing storage tanks, typically 1,000 gal, to meet the high demand of these facilities. In some cases, Evolution hot water "boilers" were also used for domestic water heating either directly, with models outfitted for domestic-water use, or indirectly, through heat exchangers.
Natural Gas DistributionSESI installed over seven miles of medium-density polyethylene piping for natural gas, along with conduit for fiber-optic cabling. Horizontal, directional drilling was used to thread piping past existing utilities, underground structures, railroads, streams, and other obstacles. "The area of decentralization is very congested by existing utilities, buildings, and traffic," said Naylor. "The use of directional drilling to install the natural gas system was done with no road closings, no impact on traffic movement and minimal utility disruption."
Propane/air StationAs a backup fuel source, SESI installed a propane/air station. This was necessary to maintain the interruptible service discount for the natural gas and minimize the site's vulnerability to utility loss. The 360,000 gal of gross storage capacity (six 60,000-gal tanks) is sufficient for a 7-day supply of backup fuel during the winter. This system allows stored liquid propane to be vaporized, mixed with compressed air, and then introduced into the natural gas main as a compatible fuel source for the gas-fired equipment. The mixture's specific gravity is accurately controlled to 1.299 to achieve identical burner/flame characteristics as natural gas. Its use required SESI to adjust the fuel-burning equipment to operate optimally under both natural gas and propane-air conditions.
When the local natural gas distributor, Columbia Gas, schedules MCB Quantico for curtailment, SESI brings the propane-air station on line. The propane/air pressure is gradually increased until it exceeds the natural gas pressure and closes the upstream check valve, thereby shutting off natural gas flow (Figure 2).
EMCSSESI supervises the boiler plants and propane air station through an energy management and control system (EMCS). Supervision includes: monitoring alarms, heating-water temperatures, and equipment status; trending natural gas use; and adjustments to operating schedules. The EMCS consists of a host/operator workstation, fiber-optic cable network, and Siemens Building Technologies' Apogee Series field panels. Boiler plants in remote buildings communicate through telephone modems.
The EMCS also monitors alarms for domestic water heaters in BEQs. During off-shift hours, a pager indicates alarms. "With our ability to monitor the operation of boilers and domestic water heaters, we can respond to alarms, correct malfunctions, and restore service usually before the tenants even know there is a problem," said Wyatt Wilson, site O&M manager for SESI.
The EMCS has also enabled SESI to minimize operating costs by reducing boiler-attendance requirements vs. unsupervised plants.
Implementation: Construction ChallengesThe project required extensive coordination with various MCB Quantico entities, such as building tenants, the environmental branch, facility maintenance department, and fire department. Coordination was also necessary with Columbia Gas, for natural gas service, and CSX, for utility railroad crossings.
Environmental review was required for emissions and architectural compliance. Despite the reduction in air-pollutant emissions that the project would achieve, its overall scale of fuel-burning capacity required MCB Quantico to obtain a new air-emissions permit from the Commonwealth of Virginia. Approval was also required for exterior flues and louvers for the many historically significant buildings.
The initial schedule anticipated a 24-month construction period. In order to meet MCB Quantico's goal of completion by the end of the current term for the central plant's service contract, however, SESI reduced the construction period to 12 months. The project team worked at a frantic pace with fast-track D-B delivery. The buildings were grouped under nine phases, with placement of equipment orders and construction beginning immediately upon design completion for each successive phase.
Shipments of prepurchased equipment were compressed such that, at one point, the 4,700-sq-ft staging warehouse was packed wall-to-wall with boilers, domestic water heaters, feedwater units, and other equipment.
Due to the scale and pace of the project, SESI engaged two primary subcontractors, Phillips Way, Inc., and Robertson Airtech, to ensure adequate manpower and price competitiveness in the construction of the heating plants. Other key subcontractors were Floyd Industrial Maintenance, Inc., for the propane/air station, natural gas piping, and fiber optic cabling, and Siemens Building Technologies for the EMCS.
As the heating plants were installed and brought online, steam service from the central plant was progressively disconnected and secured. At the last boiler plant, gas service was installed just one day prior the plant's scheduled startup. This last plant was, in turn, successfully started and brought online the morning of central plant's scheduled closure.
Design and installation plans required continuous adjustment in response to other renovation, new construction, and demolition projects in various stages of development. Communication and flexibility were the keys to making appropriate and timely course corrections against a moving target. In a case where a building scheduled for demolition required only short-term heating, SESI rented a temporary packaged steam boiler plant as a cost-effective solution. Unplanned events kept the project team on their toes throughout construction: groundwater flooding in basement mechanical rooms, discovery of existing hazardous materials, and even Hurricane Isabelle. One afternoon during the winter, the new gas main was ruptured as a result of excavation for another project. SESI repaired the main and reset affected boilers in approximately 50 buildings in order to restore operation by 7 a.m. the next morning.
"The decentralization portion of this project was very well coordinated by SESI," said Naylor. "All buildings were occupied during the conversion from central steam to gas-fired boilers. The conversions done during cold weather were scheduled for little, if any, disruption to the occupants. Most occupants never realized that their buildings were converted to the new systems."
Performance PeriodThe 23-year performance period includes contractual O&M obligations for PM, trouble-call response, boiler inspection certifications, and M&V. Using a flue-gas analyzer, SESI annually measures combustion efficiency on their fuel-burning equipment to ensure that the equipment continues to achieve the predetermined efficiencies.
Maintaining customer satisfaction additionally requires ongoing O&M and engineering support to coordinate with renovation projects and site utility excavation. SESI also provides natural gas service connections for new buildings.
After the success of the boiler plant decentralization project, Naylor looks forward to the potential of additional ESPC projects at MCB Quantico. But for now, the natural gas use has been cut by more than 50%, and the steam plumes are gone.
Sidebar: Planning for O&MBecause SESI would be responsible for the operational performance of all installed heating systems, natural gas piping, the propane air station, and EMCS throughout the 23-year performance period at the MCB Quantico, particular attention to O&M was critical in design, specification, and budgeting. To achieve the best overall life-cycle value for the project, a balance was sought between not only the installation cost, but also the reliability, durability, and maintainability of the equipment and systems.
Access and clearances for servicing equipment were essential. "When the maintenance chief taking over the project is part of your organization and reports to the same boss as you," said Robert Leftwich, P.E., project engineer for SESI, "you think twice before cramming a boiler into a phone booth." Other important features incorporated during the implementation phase included provisions for remote monitoring, chemical treatment, and piping taps for temporary backup connections. Equipment, such as cast-iron steam boilers, was selected for long life.
O&M demands for the project began in the implementation phase with the startup of the first heating plant and grew rapidly as each additional plant was brought into service. In the transition, the O&M crew participated in commissioning, received factory training on various equipment, and set up a Maximo CMMS to schedule PM activities.
The first full heating season ('04/'05 winter) was extremely hectic, as O&M staff gained familiarity and worked out bugs from the newly installed systems. "Maintaining the heating plants for over 100 buildings has proven to be very challenging," said Wyatt Wilson, site O&M manager for SESI. "However, with the highly-skilled on-site staff, our performance exceeds expectations and ensures a comfortable working environment for our customers." Although improvements and adjustments are ongoing, the pace of work settled out by the second heating season and unplanned activities are now minimal. The O&M operating budget anticipates replacement of many equipment items, particularly hot water boilers, domestic water heaters, and pumps, prior to completion of the 23-year performance period.
SESI currently has an on-site staff of seven and selected service subcontractors to conduct PM, repair and replacement, boiler plant attendances, water treatment, M&V, and support for other activities that involve the ESPC equipment and systems, such as seasonal heating/cooling plant switchovers and outage requests.