Completed Construction/Grand Opening 2012
Larkspur, CA
Slab on Grade Building resting on Piles
12,500 sq ft footprint

Terra-Petra proposed a “peer review” design of the passive methane gas mitigation system on behalf of the architect. The design engineer felt that this was a reasonable request and agreed to the review. We took no exceptions to the impermeable methane barrier membrane and venting materials specified by the engineer, however, due to the proposed foundation design we suggested alternative details for routing the horizontal vent pipe and terminating the membrane system under the building (among other comments). The design engineer not only accepted our peer review comments, but also decided to contract with us directly to serve as their methane mitigation consultant. Working together we developed a new set of details that would provide for a more efficient installation. It also reduced the number of mobilizations by the installing contractor, minimized coordination with other trades, reduced the amount of vent pipe and membrane to be installed by 20% and provided an overall cost savings to the project. Terra-Petra has since formed a professional relationship with this engineering firm and together we have completed a second soil gas mitigation design. This new building opened for business in January 2012 (construction started in the fall of 2010).