Member Spotlight: How Gary Chen Rebuilt a 1960s Brick Manhole System in Sacramento

Each month, the Manhole Recovery community highlights a member whose work represents excellence in manhole rehabilitation. This month’s spotlight features Gary Chen, infrastructure rehabilitation manager for Sacramento Regional County Sanitation District.

Background

When Gary Chen inherited responsibility for Sacramento Regional’s oldest service area — a collection system built primarily in the late 1950s and 1960s with brick construction — he faced a challenge that many engineers in older cities know well: infrastructure that predates modern standards by decades, with deterioration that has compounded quietly for years.

“The oldest manholes in our system were brick, set in lime mortar, with no liner systems,” Gary explains. “They’d survived longer than anyone expected, but the combination of age and H2S exposure had created structural deterioration that our CCTV crews were flagging in inspection after inspection.”

The Challenge: Brick Manholes in an H2S Environment

Brick manholes present unique rehabilitation challenges compared to precast concrete. The mortar joints between bricks are the primary failure point — H2S-driven sulfuric acid attacks the lime mortar aggressively, eventually reaching the brick itself and creating the “rotten egg” crumbling structure that field crews know as advanced H2S deterioration.

“Our first challenge was the surface prep,” Gary says. “On precast concrete, you have a relatively uniform substrate. On brick, you have mortar joints at different depths, bricks at different heights, varying moisture conditions. Getting an adhesive coating system to perform consistently across that heterogeneous surface was the first technical problem to solve.”

The Solution: Cementitious Rebuild + High-Build Polyurea

After working with both the Manhole Recovery community forum and his material suppliers, Gary’s team settled on a two-step approach for the most severely deteriorated brick manholes: first, a cementitious structural rebuild to create a uniform, sound substrate, then a high-build polyurea application to create the impermeable protective barrier.

“The cementitious step is critical for brick,” Gary emphasizes. “You’re not just filling mortar joints — you’re creating a continuous, uniform substrate that the polyurea can bond to predictably. If you skip it and go straight to polyurea on deteriorated brick, you’re going to have adhesion problems.”

For manholes with less severe deterioration (MACP Grade 2), Gary’s team developed a protocol using a penetrating epoxy consolidant on the brick surface before polyurea application — creating a chemical bond between the coating and the brick matrix without requiring the full cementitious rebuild step.

Results and Lessons

Over three years, Gary’s program has rehabilitated 312 brick manholes with zero post-installation adhesion failures at annual QC inspections. Five-year flow monitoring data shows a 7% reduction in wet-weather I/I in the rehabilitated service area — consistent with the program’s I/I reduction goals.

“The lesson I’d share with anyone facing brick manholes is: don’t assume the rehabilitation approach that works for precast concrete will work the same way for brick. Understand your substrate, test your system on a representative sample of the worst conditions in your inventory, and build the QC protocol that matches the substrate’s variability.”

Gary will be presenting the full technical details of this program, including the substrate preparation protocol and QC test results, at the Manhole Recovery Annual Forum in Nashville this October. He’s also offered to answer questions in the community forum — search for “Gary Chen brick manhole thread” to find the discussion.

Connect With Gary

Gary is an active member of the Manhole Recovery community and welcomes questions from other engineers working with brick or block manhole infrastructure. Join the community to connect.

Want to be featured in a future Member Spotlight? Contact us to share your story.

Related reading: Comparing Rehabilitation Methods | H2S Corrosion Science | Case Studies Library