Mill 19 Turns a Dead Steel Mill Into Pittsburgh's Robotics Hub

By Daniel Okafor

A steel frame that once carried one of Pittsburgh's largest mills now carries solar panels. Mill 19, the former Jones and Laughlin steel plant in Hazelwood, has been rebuilt as a hub for technology, robotics and advanced manufacturing. Its tenants include Carnegie Mellon University and the Advanced Robotics for Manufacturing Institute.

The conversion is the work of the Regional Industrial Development Corporation of Southwestern Pennsylvania (RIDC), a non-profit developer. RIDC is redeveloping the wider Hazelwood Green site. John Buechli, RIDC's senior construction manager, frames the project against the collapse of Pittsburgh steel in the 1970s and 1980s. That collapse, he said, "left a hole that needed to be filled." He added: "Our mission is to bring jobs and money back to these areas."

How adaptive reuse works here

The designers kept the mill's steel skeleton instead of demolishing it. The practice is called adaptive reuse. It keeps the metal out of landfill and preserves the memory of a site that ranked among the city's biggest steel producers. New solar arrays now hang from the old frame.

Three new buildings sit inside the original footprint. Architecture firms MSR Design and R3A led them. The buildings house classrooms, offices and labs. They use passive design to cut energy consumption.

The salvage numbers are concrete. Landscape architects recovered 100,000 sq ft of the factory's concrete floor. Concrete rubble became landscape elements and furniture. Salvaged steel became railings, play equipment and benches.

Who shaped the landscape

Two studios, Ten x Ten Studio and Dirt Studio, designed the outdoor areas. Their brief was to draw people in and make them comfortable, said Maura Rockcastle, Ten x Ten's principal and co-founder. But comfort did not mean erasing the industrial scale. Rockcastle said she wants human-scaled landscapes "without getting rid of the power of the big stuff."

A quarter-mile channel planted with native trees and grasses filters stormwater and keeps it out of the sewer system. It also softens the structure visually. The outdoor spaces alternate between open and enclosed. "We were able to create all these intimate pockets that were all very different," Rockcastle said. "The character of the planting around them also changes as you move through that water system."

Why the designers kept the past visible

The site's history drove the material choices. "The stance that we were taking early on is that these materials, these stories, have value," Rockcastle said of the industrial past. "You don't need to remove or erase them."

Julie Bargmann, principal of Dirt, put it in stronger terms. "I think the best projects that are industrial adaptive reuse will give you that feeling of, like: 'Oh my God, so much happened here that we don't know about — we should honor it,'" she said.

Bargmann also stressed public access. "What's kind of groovy with these industrial sites is that they have an identity and long connection to a community," she said, referring to Hazelwood residents and Pittsburgh at large. "So we always advocate for keeping it open and accessible" to people beyond the tenants.

What comes next for Hazelwood Green

Hazelwood Green is still under construction. More housing is planned. Buechli wants to open retail and commercial space there in the future. The designers' stated goal is that the district becomes a local destination, not just a workplace for the robotics labs and university offices inside Mill 19's frame. The bet is that reused steel and salvaged concrete can anchor the same economic recovery their original construction once symbolized.