With a population of nearly 66,000, Eau Claire is the ninth largest city in the state of Wisconsin and it takes its name from the original French name, “Eaux Claires,” meaning “Clear Waters.” This is an appropriate reference, as it sits at the junction of the Chippewa and Eau Claire Rivers. As part of the city’s recent revitalization project, the Pablo Center at the Confluence, a local arts venue designed by Holzman Moss Bottino of New York, NY, was erected and its architecture is a striking representation of local building materials, including hornblende stone.

The arts center is only a portion of a larger redevelopment effort to unite the arts, enterprise and education to the site, rejuvenating the historic downtown while elevating the quality of residents’ life. Project Manager Gilbert Oh, AIA, LEED AP of Holzman Moss Bottino Architecture explained that the design objective was “to create an active center for entertainment and cultural enrichment that reflects the natural and artistic beauty of Eau Claire.”

The conception of the new Pablo Center at the Confluence was a collaboration between multiple public and private entities, including the City of Eau Claire, Eau Claire County, Chippewa County and multiple local private donors. Additional constituent groups include the University of Wisconsin – Eau Claire Department of Theatre Arts; Visit Eau Claire; regional music organizations and many local theatrical companies. They were involved from the early programming and conceptual design phases and remained actively engaged throughout the building’s construction. Additionally, a majority of them assisted in the public fundraising process, which entailed focused community and donor presentations with a wide range of materials presented from renderings to building products.

The exterior facade of the facility is a prominent display of Aqua Grantique, a blue-green hornblende stone supplied by Krukowski Stone Company, Inc. “As a local material, the stone is one of the elements and materials that physically reflect the region,” said Oh. “It is also a distinctive material throughout its large expanses — highlighting its importance with the community and its importance in the redevelopment of downtown Eau Claire.

“The hornblende stone was found in an exploration of local materials in the state of Wisconsin,” the architect went on to explain. “The quarry is just a few hours’ drive from the site. The dark stone was selected because of its distinctive veining and subtle variations in color. Masonry is a common facade material for the historic building fabric in downtown Eau Claire, though the dark stone stands out against the lighter colored stone and red clay brick typically used.”

A visit to the quarry

Malcolm Holzman, FAIA, Partner at Holzman Moss Bottino Architecture, explained how his visit to Krukowski Stone Company to examine the material in person was a critical part of finalizing the stone selection. But before a trip to the quarry was planned, there was initial research, which included reading information on the company’s website, telephone calls, additional detailed conversations and reviewing small samples of the stone that had been shipped to the firm’s office. According to Holzman, this was important to establish that the product met the design and budget criteria.

“Krukowski quarries and fabricates a variety of stone types,” said Holzman, adding that he took the trip with Evan Delli Paoli from the firm. “In the showroom, we met Joanie Krukowski-Whitt. Her brother, Jeff, founded the company in 1978. Evan and I carefully examined the sample material panels on display in the showroom. The most striking was called ‘Aqua Grantique,’ a hornblende/gneiss; dense, very dark and almost black with random white veins. We were told it was most frequently used for commercial and high-end residential projects. This material was well priced and unlike granite from Wisconsin, within our budget.”

After viewing the hornblende stone in the showroom, the architects went to the nearby quarry. “Although the site was icy, it allowed us to see the material in place,” explained Holzman. “This was important, as it provided an understanding that large blocks would be difficult to extract and fabricate. We examined cut faces at extraction points in the quarry and the overall color and veining was relatively consistent.”

Afterwards, Holzman and Paoli made a stop at the fabrication facility where they were introduced to the owner, Jeff Krukowski. They were able to see a block of hornblende sawn into slabs and then split into smaller pieces. “We inspected the split surfaces to understand the dimensional variation along the length and width of any given piece,” said the architect. “The tolerances were acceptable for a veneered cavity wall installation. We requested samples for further review at our office.

“Following a thorough consideration of the stone, we decided it would provide special character to the exterior facade of the Pablo Center at the Confluence in Eau Claire,” Holzman continued. “This performing arts project had a modest budget and a considerable amount of the funding was being privately raised. Although the material was more expensive than brick, it provided a distinct appearance. At the client workshop following the quarry and fabrication tour, we presented the hornblende as a primary exterior finish. Two large sample blocks were delivered from Mosinee for the review. Considerable interest and discussion followed. Almost to a person, none of the client design committee members were familiar with the stone, including the contractor even though the quarry was only 50 miles away. This presentation precipitated continuing discussions at following meetings.”

Holzman explained that there was considerable deliberation, which resulted in the hornblende stone being illustrated in the construction documents and project renderings. “During and just after bidding, the contractor had questions,” he said. “Did we know how much hornblende weighed? How could a mortar joint be maintained with a split-face material? And he had others.”

The height of each block was also a topic of debate, according to Holzman. “The cost estimate for the total project was satisfactory, but value engineering was needed since fundraising wasn’t complete,” he said. Working with Strang, Inc., the local Architect of Record, the design team sought out ways to keep the stone in the project. “The hornblende was an obvious target,” said Holzman. “After many months of discussion, questions persisted: Could brick be used? Could less expensive stone be used? Could smaller pieces be used? It was decided that a member of the design/steering committee should visit the Krukowski operation. Following this tour, the stone became part of the project. Construction logic then dictated the remainder of the process.”

Constructing the arts center

Approximately 25,200 square feet of the hornblende stone was used for the 144,300-square-foot building which is stationed on an 84,400-square-foot site. Each piece has a sawn height of 3 ½ inches, with lengths varying from 6 to 36 inches and depths between 3 to 5 inches.

According to Oh, the masonry face was split-face, which created the varied depth range. “Stone pieces had to be carefully selected to avoid visible flat sawn faces from above; mortar had to be carefully applied to maintain a consistent recess from the staggered face of the stone; and a minimum air gap behind the stone needed to be maintained for proper ventilation,” he said. “The size and weight of the pieces for installers was also a consideration in selecting the final size of the pieces. In the end, the pieces ended up being more manageable than feared by the installers.

“The design team made multiple site visits to review the free-standing mock-up and worked with the construction team to strategize final construction method,” Oh continued. “Photos were reviewed regularly to ensure installation remained consistent and per agreed upon methods. Mortar joints and how the corners came together, including the selection of corner pieces, were two critical items reviewed.”

Contrasting against the dark stone surface, wave-like copper-clad projections and canopy mirror the movement of the adjacent rivers. Grand expanses of glazing offer framed views of the rivers and city, further solidifying the sense of connectedness between the Pablo Center at the Confluence and its site.

According to Holzman, the dark stone and dark mortar permits the stone building surfaces to appear as large textured planes. “They are the foreground character of the building,” he said. “It sets off the large windows with small colored inserts in the multi-story openings. He added that it minimizes the dark metal clad mechanical enclosures and accentuates the copper waves — enclosing special interior spaces — that protrude from the facades.

“The copper will transition from a bright reflective surface, to a matte brown, and finally to a patinated green in a few decades,” he said. “The stone will darken slightly over time to reveal the final personality of the project.”

The Pablo Center at the Confluence, which features two major performance spaces — RCU Hall, a 1,200-seat multipurpose venue, and the JAMF Theater, a 400-seat flexible theater, as well as four additional rehearsal/presentation rooms — was completed in a little under two years. “For the grand opening, mementos were made for major donors and contributors to the project from the stone with the name of the project and individual’s name etched into the top,” said Oh. “We have had a very positive reaction among users/occupants, community members, the construction and design teams.”