Although a cloak of nostalgia hangs over the quarry-to-reservoir conversion, city officials embraced the opportunity to increase the city’s water reserves from an insufficient five to seven-day supply to a 30 to 90-day surplus.
According to Atlanta’s Senior Watershed Director, Ade Abon, “The increase in raw water reserves will prove crucial if ever the city experiences a day without water from the Chattahoochee River – its only source – with an economic impact of $250 million a day. We need this.”
Efforts then shifted to the painstaking process of coating the tubular interior surface with reinforced concrete and grouting. The resulting leak-proof, impermeable lining will contain the powerful sluice of river water.
As the connective tunnel took shape, construction began on the quarry and treatment plant buildings, which were needed to house the pump stations, office space, workshops, and electrical equipment. Although functional in nature, these structures will also blend into the Westside landscape.
Tom Steele, Senior Architect and Lead Designer for the Atlanta-based PRAD Group, explained how Echelon’s InsulTech pre-assembled single-wythe insulated masonry units fit his distinct specifications for both structures.
“Low-maintenance, cost-effective materials were a priority for both the Hemphill and Bellwood Quarry sites,” said Steele.
He found Echelon’s labor reducing and time saving CMU system to be a superior choice compared to traditional multi-step insulated cavity walls.
“It provided true continuous insulation, durability, and minimal maintenance we wanted to achieve, in a three-part system that resulted in dramatic savings,” Steele noted.
The system combines structural CMU, EPS foam insulation, air/water barrier and exterior veneer into a single 12 and a quarter inch unit, delivering above-code energy performance without sacrificing the masonry aesthetic.
To create this appealing visual, Steele chose a native precast concrete finish, which will cast a beautiful reflection on the adjacent reservoir surface. In an innovative move, the designer flipped the InsulTech 3-part block, so the Trendstone in Sundown color faced inward, for an attractive, polished effect.
The structure’s focal-point entranceway – bookended by two soaring pilasters – forms a gateway for the striking arched-glass doorway. The designer’s overall vision resulted in a magnificent blend of form and function.
“For the interior, it made sense to have hard surfaces that were insulated and had some thermal protection,” Steele explained, “since the space where the pumps operate will not be climate controlled with year-round temperatures ranging from 55 to 100 degrees Fahrenheit. InsulTech was perfect for this.”
While smaller in scale, this part of the project plant required some complex coordination by masons. Drew Lamberson, Project Manager and Estimator with Bibler Masonry Contractors, Inc. explained the situation.
“This was the first time InsulTech was used in Georgia, so we all benefitted from some training with the system,” said Lamberson.
Echelon provided in-person assistance throughout the build to help streamline installation of the innovative design.
Since these buildings will be visible to the public, Steele selected Trendstone and Mesastone architectural units – prefinished, integrally colored concrete blocks – as the outer faces for the InsulTech system. The units are manufactured with one or more faces ground to expose the variegated colors of the natural aggregates. A pre-applied clear satin gloss acrylic enhances moisture resistance and adds a glossy finish.
“If you see the buildings up close, you’re pleasantly surprised by the pattern you might find in the wall,” said Steele. “The InsulTech with the Trendstone and Mesastone finishes give them a nice feel. We want folks to know municipal funds are going toward something nice, especially since these are enduring structures.”
In the past, the PRAD Group has worked with the Atlanta Watershed Department on several projects to ensure that the city’s increased pavement areas get retrofitted with optimal storm water drainage solutions.
For the Hemphill accessway, Steele explained, “We chose Belgard’s Aqualine 9L Permeable Paver, a 9-inch by 9-inch profile, because the L-shaped paver fit the area well.”
The same Permeable Interlocking Concrete Pavers (PICPs) had been installed in a nearby Atlanta neighborhood, distinguishing it as the largest PICP retrofit project in North America.
“It also had the benefits of LEED points and drainage properties, as well as its ability to stand up to the regular heavy truck traffic. Aqualine 9L helps to keep the water on the site just long enough to actually seep back into the earth and prevent run-off," added Steele.
While Atlanta recorded record-breaking downpours this past winter, the Aqualine pavers kept the Hemphill accessway puddle-free. After inspecting the area, Watershed Director Abon confirmed, “The pavers look great and have held up well.”
“After the inner coating was completed, a purging of debris was necessary to remove any construction by-products.”
Other recently completed aspects of the initial phase included placement of a permanent plug at the entry point to hold back the forces of the Chattahoochee River. In addition, two slow-control shaft systems at entry and exit points were installed to regulate water flow between the river and the basin.
Once the reservoir is filled, reserves can then be channeled as needed to the nearby Hemphill Water Treatment Plant. Abon estimated the length of time to fill the gorge at five to six months. However, several variables will come into play including customer need, treatment plant capacity, and Mother Nature.
“The underground work was completed at the end of March, and the raw water release began in mid-April.” The water flowing into the new emergency reservoir will eventually hold 2.4 billion gallons of water.
This milestone event marks the completion of Phase I of Atlanta’s large-scale Westside overhaul. Although the Bellwood Reservoir is too small for recreational use, the ripple effects from this transformational endeavor will be felt throughout the City of Atlanta.
Phase II of the multi-phased effort broke ground this summer, as planners begin to shape the contours for Westside Park, a 280-acre multi-use recreational space predicted to attract droves of developers. With an injection of public and private funding, change is inevitable for the landscape of Atlanta’s long-neglected West Side. Park trails are configured to connect with the Atlanta BeltLine – a pedestrian/bike pathway designed to eventually loop around the entire metro area making the area even more accessible to Westside commuters.