Old world charm will meet modern technology once construction of the reimagined Main Fountain Garden in Pennsylvania’s Longwood Gardens – one of the premier horticultural display gardens in the United States – is complete. This $90 million project involves replacing the aging infrastructure supporting the Gardens and providing new engineered systems and enhancements to the landscape, site, and fountains while retaining the European aesthetic intended by Pierre S. du Pont, garden founder and designer. Plans call for restoration of the historic gardens and rectangular basin building and the preservation of the existing pump room for use as a museum.
Urban played an integral role on this project by providing civil, site, mechanical, electrical, and plumbing engineering services, as a subconsultant to the project designer. Longwood’s goal is to enhance the visitor experience and elevate recognition as a world-class destination. To meet these goals, maintenance functions need to occur underground, through a network of tunnels. The engineering challenge was to provide heating, cooling, and dehumidification services that would be invisible and inaudible to garden visitors. Our solution was an offsite geothermal condenser water loop system.
The new structure, which houses the fountain equipment and horticultural and facilities workrooms, is ventilated from an underground mechanical room using a concealed air intake. The entire underground network of tunnels and remote pumping control rooms is ventilated, conditioned, and de-humidified to allow for operation of the fountains during colder weather. The roof of the new structure forms the basin for the main fountain display. A benefit is that the ventilation system can be isolated during fireworks displays to prevent contaminated air from entering the building.
A critical part of the project was replacement of 80-year-old underground utilities, which were deteriorating and failing. These utilities crossed the site selected for construction of the new underground pump rooms. To allow the vast excavation to occur without disrupting other attractions at Longwood, the utilities were rerouted around the site.
Other utility work included redesigning the site power distribution to provide a higher voltage than the current electrical distribution center provides. Our design includes a distribution sectionalizer that will provide capacity to meet the future electrical needs identified in the Garden’s 40-year master plan. In addition, we are designing a new electrical substation on an adjacent site to provide back-up power for the new fountains and other facilities identified in the master plan.
We also worked with Longwood to reduce the environmental impacts of the revitalized garden — one way was specifying engineered soils and pervious surface materials to reduce the site’s stormwater runoff. Another sustainable design feature is the geothermal loop, which heats and cools the facility without burning fossil fuels.