Time Bypass

(Editor's note: This peek into the design of Frederick Memorial Hospital, Frederick, Md., is the beginning of an ongoing "project diary" that will break down different aspects of the hospital project's development from initial meetings with the architectural and hospital team, to permitting issues, to specifics about the major M/E systems, including special IAQ issues, construction and system t...

By Michael P. Sheerin, P.E., Healthcare Division Director, TLC Engineering for Architecture, Orlando, Fla. April 1, 2003

Renovations and expansions of hospitals are fairly routine. But transforming an aging facility from a bewildering array of zigzag corridors to a modern, high-tech hospital is another matter altogether. Such was the case with Frederick Memorial Hospital, a 233-bed hospital that was a composite of seven interconnected additions to its original 1902 wood-and-brick structure. Situated on a compact campus, the hospital was built to serve the budding agricultural areas west of Baltimore and northwest of the nation’s capital. Over the past decade, it has experienced steady admissions growth, as Frederick County evolved into a bedroom community for the rapidly developing I-270 technology corridor in the nearby Washington, D.C./Rockville, Md. area. In short, Frederick Memorial was quickly outgrowing its space and required major expansion.

Planners had considered building a replacement hospital but decided it was not fiscally sensible. First, the compact campus was integrated into the fabric of the community; it was centrally located and easily accessible from the city’s main thoroughfares. Second, major portions of the hospital were not in need of replacement—notably, the operating suite and laboratory. Finally, a new site, even if one were available, would significantly increase the project’s development costs.

Programmatic goals, however, identified the key needs: Improve the birthing/women’s center; expand the emergency department; expand the operating suite; and provide all-private patient rooms.

The question was how. The hospital’s winding, bustling corridors foreshadowed the challenges ahead. That premonition was realized when architect Noelker and Hull Assocs., Chambersburg, Pa., established the project’s underlying goal: Make the hospital as accessible and functional as if it were newly built.

Further analysis unveiled a clearer picture of what needed to be done: multi-phase construction that would include demolition and numerous additions, yet maintain use of all hospital departments and all patient beds, while expanding M/E/P system capacity as needed and ensuring reasonable public and construction access.

The design team condensed the project into three phases:

  • Expansion of the central energy plant (CEP).

  • Addition of new clinical areas.

  • Addition of a new patient tower/birthing center.

Each phase involved clustering the multi-phase design and construction activities into a distinct, biddable document package. A temporary intensive care unit relocation was later spun off for early design and construction as an opportunity for the design team to work out the kinks of decision-making and information flow on a smaller scale.

The tale of the tunnel

The focus in this preliminary examination of Frederick Memorial is on dealing with piping distribution affected by this maze and other plumbing-related matters. The next installment will look at the central plant and the specific systems installed within—a task that in and of itself took two and a half years to bring to fruition. But the backbone of the project, from an M/E/P perspective, was a new utility sub-tunnel that would connect the reconstructed plant with the rest of the hospital.

As noted, multiple additions created a tangle of corridors that also affected basement areas, because dense piping distribution at ceilings and walls impeded any new distribution.

The existing hospital’s limited sub-basement area did include a tunnel that connected a core juncture to the far end of a sizeable addition built in 1985. This structure provided a walkable pathway through the web of mechanical and electrical distribution mains, racked floor-to-ceiling. Other ancillary, crawlspace-dimensioned tunnels were also in place, but offered only limited functionality.

To consolidate these passageways—and meet the needs of the facility’s projected growth—the new sub-basement tunnel was conceived. Specifically, this sub-tunnel would provide the distribution path for chilled water, steam, condensate, medical gas, domestic water, natural gas, oxygen, normal power and emergency power, tapping off at locations determined at each phase.

Tunnel cross-sections were developed for the CEP project, with mechanical pipe racks on one side of a walkway path and electrical conduit racks—arranged emergency-over-normal—on the other. Overall tunnel dimensions were established and the racks were arranged with spaces for future use. A sump and floor-drain network was also incorporated.

The necessity to begin the tunnel installation presented a design challenge similar to the experience of selecting the major equipment going into the revised CEP— committing to design decisions of capacity, arrangement and size. This was slightly problematic in that phase 2 and 3 architectural information—the basis for M/E/P decision-making—was conceptual and schematic at best.

As a result, rough calculations for load estimates were developed based on benchmarking and on a heavy reliance on experience. In particular, the physical arrangement of the new rack system was based on the anticipated downstream connections with the future phases.

Best laid plans…

As is the case with many projects, the best laid plans of mice and men often go astray, and such was the experience with the hospital. To facilitate internal circulation as the central plant’s design was wrapping up and construction was starting in the spring of 2002—and plans for Phase 2 were getting underway—the architects determined it was necessary to put in a new corridor for material flow to and from the loading dock of the expansion into the existing hospital. While this made tremendous sense, the plan routed the corridor through the pipe-laden distribution rack in the basement level. After the shock and awe, the issue became how to best make it happen. While the existing rack, itself, was congested and offered no capacity to support expansion, it still served significant areas of the hospital, meaning new distribution was necessary.

The good news was that the planned sub-tunnel had the capacity to re-feed the affected systems. Unfortunately, it was distant from the proposed corridor tie-in point. Then inspiration struck: If a spur of the sub-tunnel were extended to a largely unusable space behind a stair tower, a pipe connection chase could be created.

Thus, the sub-basement tunnel design was refined to incorporate a “T” at the midpoint of the Phase 2 extension (see figure, upper right). This decision resulted in a lot of head scratching, as mechanical designers had to develop new cross-sections to maintain the walkways that would now also route through the tunnel’s mechanical pipe rack. All of the existing basement rack piping was reconnected to new services from the tunnel on the far side of the new corridor in the bi-level sub-basement and basement pipe chase. The abandoned piping and rack were then removed.

In hot water

Although the majority of the new infrastructure needed to support the expanded hospital was placed in the CEP to better serve the building, certain systems were still located within the hospital, itself. For instance, the heating and hot water system for the expansion areas is situated in a basement mechanical room, centrally located to distribute to the various expansion areas. Generated by multiple steam-to-water, shell-and-tube heat exchangers, the heating water system is a variable-temperature, variable-flow system with distribution pumps equipped with variable-speed drives circulating 180r system, consisting of four semi-instantaneous-type steam-to-water generators set at 110ºF, is placed adjacent to the heating water system, sensibly sharing low-pressure steam and condensate mains. More importantly, the new domestic hot-water system is in close proximity to hot water tanks and associated hot water main distribution. Although the tanks, which use immersion-type steam generators, are being taken out of service, continuity of the hot-water main distribution required connecting the new system to the existing system.

Abandoning the hot-water tanks also reduces the potential for the domestic hot-water system to harbor microbiological agents, such as Legionella, which can be especially dangerous to hospital patients afflicted with weakened immune systems. A copper-silver (Cu-Ag) ionization system was also incorporated into the domestic water supply to the domestic hot-water system to further minimize that risk. Cu-Ag ionization works by regulating an electric current between copper and silver electrodes, causing copper and silver ions to be released into the water. These ions attach to particles of opposite polarity, typically microorganisms, and neutralize them.

Previously, the hospital had used a gas-chlorination domestic water treatment program, but experienced problems from piping and joint degradation of the galvanized hot-water piping that was used in some older building areas. Research and discussion with the hospital staff led to the use of the Cu-Ag method. These areas were noted in the facility assessment, and new domestic hot-water mains, where feasible, were routed to replace these troubled pipes.

Specialty piping matters

In regard to other internal piping systems, the decision was made to install new medical vacuum and medical air systems that would be sized to support the entire hospital. These systems were tied into their existing counterparts, which in turn, were valved off, but left in place to provide an alternate source of limited capacity should it be necessary—the backup that hospital facility folks can’t resist.

With three 15-hp oil-less reciprocating compressors, dual refrigerant air dryers and dew point and CO monitoring, the medical-air system isn’t likely to need much backup. As demand increases with the completion of the various project areas, the system will respond by operating first one, then two compressors as necessary to meet capacity. The third compressor is held in reserve for redundancy, and automatic controls ensure equal compressor runtime.

The new oil-sealed liquid ring medical vacuum system, with triplex 20-hp compressors and a 200-gal. receiver, provides similar flexibility to respond to the evolving facility’s demands. It also helped the hospital’s administrators get their building construction permit. (Look for more about how water conservation affected permitting in an upcoming installment).

New nitrogen and nitrous-oxide gas manifolds were installed to meet the capacity of the expanded surgical suite. Each system consists of two banks of six 254-cu.-ft. cylinders, with an automatic changeover control to ensure uninterrupted service. Space was also allocated for the future addition of a CO 2 manifold.


In the end—of at least phase 2—important medical care spaces were created along with some important spaces for people and computer equipment. A grand concourse entry, complete with drive-through drop-off canopy and vaulted, sky-lighted reception space, provides a focal point and reference point for patients and visitors. The new main corridor extends, without zigs or zags, directly into the core of the hospital. This main corridor will intersect a similar corridor in phase 3 to create a concise, navigable public way. Burrowing such space through the existing building necessitated offsets for numerous plumbing and risers, and the re-fit of HVAC, fire sprinklers and lighting in the affected areas.

“Project 2000,” as it was dubbed by the hospital from the outset of planning, turned out to be a misnomer from a chronological standpoint. But the name still conjures the spirit of hopefulness that welcomed the new millennium and the hospital’s new readiness to serve Frederick County into its second century.

Hospital Expansion Costs and Numbers at Glance

Phase Demolition (sq. ft) Construction Area (sq. ft) Construction Cost
New Renovated
CEP 3,270 6,750 5,930 $7.5 Million
Phase 2 43,000 111,340 65,950 $27.4 Million
Phase 3 84,665 171,225 62,680 $43 Million

She’s Gonna Blow—Tower Sump Crisis

The hospital’s original cooling towers drained into a pair of 2,000-gallon remote sumps—essentially rectangular vertical condenser water storage tanks. One was located in the chiller room, the other outside at grade due to space constraints. This arrangement allowed the towers to operate without basin heaters. This scheme was left in place, as at first, it seemed a reasonable, cost-saving decision. Upon inspection, however, it was revealed that the elements had taken a toll on the exterior-mounted sump’s structural integrity. Moving the sump produced further stresses, and when it was finally re-filled with water, it presented a frightening bulge at mid-section. The sump was drained, angle iron bracing was added inside and the sump returned to rectilinear form.

Concerns about sump capacity during peak cooling load conditions and the dynamic impact of multiple condenser water pumps operating resulted in a simple solution: Flood the tower’s basins in the summer months. The additional condenser water available for circulation ensures that the condensed water pumps won’t run “dry” and will provide a larger, more stable heat sink. A two-stage make-up water assembly was employed. A float assembly controls winter fill mode in one of the remote sumps. Summer mode, on the other hand, is engaged by manually opening a valve leading to make-up connections at each cooling tower. The winter mode float stays satisfied, as the remote sumps become fully flooded along with the tower basins.

The remote sumps’ air vents extend above the cooling tower basin level, because the static water level could otherwise allow the water to flood out.