The University of Vermont Medical Center (UVMMC) is the largest employer in the Green Mountain State. Situated on the top of a hill, this campus is surrounded by quiet neighborhoods. Over time, the hospital has expanded and the loading dock has seen an ever-increasing frequency of deliveries at all hours of the day. The neighborhood at the bottom of the hill along East Avenue was being subjected to loud noise from commuter busses and delivery trucks. The noise was being projected directly at the second level of these homes.
The hospital knew that the result of this project would be a sound absorption wall and they knew through an existing relationship with Engineering Ventures that modern innovative design techniques would be able to create something that is both functional as well as aesthetically pleasing.
This is also true from the neighborhood’s point of view. Although their main concern was to limit the volume of noise generated from the hospital, they also did not want to see a large monolithic concrete wall on top of the slope. The landscape design by Wagner Hodgson neatly blends the wall into the natural surroundings using creative planting techniques to go above and beyond a simple concrete wall.
The Sound Wall was proposed at the eastern edge of the hospital campus, at the top of a well-established, forested east-facing slope leading down to East Avenue and the adjacent neighborhood. The design created a sound barrier between the UVMMC loading dock and cooling towers at the top of the slope from the immediately adjacent neighborhood to the east.
The wall design consists of articulating sound absorptive panels placed between steel posts and is supported by cast in place, drilled shaft foundations. This strategy creates the least disturbance to the surrounding vegetation and numerous existing utility corridors. Both sides of the wall are engineered to be sound absorptive to ensure audial separation of the Medical Center and neighbors to the east.
To minimize the length of the wall and to work with the existing roadway and topography, the north and south ends of the wall pivot inward slightly toward the west, connected by a long straight section.
Approaching the wall along Mary Fletcher Drive from the north and south ends, dense, native plantings mask the ends of the wall, and help to create a transition between the forested slope and the wall’s twelve-foot height. These plantings at the wall’s ends include hardy, low-maintenance deciduous trees, shrubs, ornamental grasses, and perennials. The wall’s articulating panels set the rhythm of planting along the wall’s length.
Beyond the planted transitions, there is continuous band of planting along the middle straight section of the wall. To visually reduce the scale and expanse of the wall, every other panel is recessed and planted with salt-tolerant, low-growing shrubs and vines that will grow to the top of the wall. Plantings at the north end of the wall will be visible looking south from Colchester Avenue; plantings at the south end of the wall will be visible from East Avenue.
The location of the wall is in between the edge of Mary Fletcher Drive and the top of slope of the hill leading down to East Avenue. The tightest section left 6 feet from the edge of road to the top of slope. The hill itself consists mostly of fill material dating back to the original creation of Mary Fletcher Drive. Extensive historical research and underground utility location was performed to determine the locations of existing live underground utilities and old abandoned utilities.
Soil borings determined that there is more than 15 feet of sandy fill material before reaching natural subgrade material suitable to support loading from the piers and rotation due to live wind loads. We coordinated with Sanborn Head to design the piers. During installation the contractors used a combination of auger drilling and vacuum drilling to avoid critical live utilities to the hospital. Because of the quality of background research, only one issue was encountered while drilling the borings. The auger hit a solid concrete block approximately 10’ below grade. It was determined to be part of the historical fill material and did not cause any problems. The narrow constraint between Mary Fletcher drive and the slope proved challenging to not only cast the piers, but to prevent erosion down slope.
The wall construction brought multiple professional disciplines together to achieve a common goal. RSG performed noise control studies. Sanborn Head performed geotechnical design. Wagner Hodgson performed landscape design to minimize the visual impact of the wall. E4H consulted architecturally on the wall to avoid a monolithic concrete structure as seen on the side of highways. Engineering Ventures performed the civil site layout as well as the structural design of the wall itself.