Case Study: Methane Consulting - Twin Cities Police Headquarters Larkspur, CA
12,500 SF | Slab-on-Grade on Piles
THE CHALLENGE
A passive methane mitigation system had already been designed for a complex slab-on-grade building supported by piles. The architect requested a peer review—smart move, because pile-supported slabs + methane systems = coordination headaches.
The risk:
- Inefficient installation
- Excess material usage
- Trade coordination conflicts
- Higher overall project cost
SOLUTION
Terra-Petra conducted a peer review of the methane mitigation design.
- Validated core system components to ensure no unnecessary redesign elements
- Identified inefficiencies in vent piping + membrane termination due to the pile foundation system
- Redesigned horizontal vent routing + membrane detailing for constructibility
- Collaborated directly with the design engineer
OUTCOME
- ~20% reduction in vent piping and membrane materials
- Fewer contractor mobilizations
- Simplified coordinationacross trades
- Lower overall installation cost
- Project delivered and operational (opened January 2012)
TAKEAWAY
Good methane design isn’t just about compliance—it’s about constructibility and cost control.
Most firms stop at “it works.” Terra-Petra drives to “it works efficiently in the real world.”