Favorite Build: Gary’s Insight on the Mill Creek Drainage Relief Tunnel

• August 28, 2026

August 28, 2026

Every project leaves an impression, but for Gary, Concrete Batch Plant Manager, one build stands above the rest. The Mill Creek Drainage Relief Tunnel in Dallas, Texas is the largest stormwater relief project in North America and the first stormwater tunnel of his career. Drainage problems along the alignment were identified as far back as 1970, and the storms that followed made the case impossible to ignore. A single May 1995 event flooded the Baylor Hospital emergency room and closed Interstate 30. Gary noted "I've applied my expertise of concrete toward something I haven't experienced at this magnitude previously, especially on heavy civil projects." The build asked him to hold that expertise steady across 130,000 cubic yards, and it proved that quality at scale is won one placement at a time.

A Project of Record Scale

• Five miles of tunnel driven through the Austin Chalk limestone formation, two miles at 37'7″ of excavation and three miles at 32'7″
• An unreinforced concrete liner 15 inches thick, totaling 130,000 cubic yards in the main tunnel and roughly 170,000 cubic yards across the full job
• Eight shafts ranging from 100 to 180 vertical feet in depth and from 14 to 45 feet in diameter
• Agitating hoppers carrying 13 cubic yards apiece at roughly 60,000 pounds fully loaded, feeding formwork that places up to 100 linear feet of liner per pour

Moving Concrete Miles Underground

What made the work demanding was not the volume alone. It was the distance between the plant and the pour. Every yard traveled as far as five miles underground before it reached the forms, and each load had to arrive with its strength and workability intact. A mix that stiffened in transit would idle the crew and the formwork waiting behind it.

Gary designed the mix to reach high strength as quickly as possible. Faster strength gain meant forms could be stripped and reset sooner, which kept the lining operation advancing down the tunnel. The harder requirement was repeatability. Every yard leaving the plant had to match the yard before it.

Getting to Every Time

Production did not start where it finished. The early placements surfaced problems that only appear at full scale, and the plant worked through them one pour at a time. "Since we started producing concrete for Mill Creek it hasn't always been as efficient as it is now," Gary said. "We overcame trials and tribulations with each placement until we were successful every time."

What he points to is that progression. The plant reached a point where a placement no longer produced surprises, and holding that line across 14,400 truckloads is its own kind of record.

Lessons That Carry Forward

The lesson Gary takes out of Mill Creek has less to do with mix design than with the people standing around it. Working under the project manager, he built the relationships that keep material moving, particularly with the construction materials testing team and the owner. Approval of a placement rests on those relationships as much as on the batch ticket.

"Work closely with the project team and develop a good relationship with the construction materials testing team and the owner to help move the project forward," Gary said.

Mill Creek was the second tunnel of his career and the first of its kind in North America. The mix designs will change on the next job. The habit of working across the table will not.