The Kirkham Project proved an ideal opportunity to explore the feasibility of this novel approach. Nestled against the Mount Sutro Open Space Reserve in the Inner Sunset, the existing topography of the site requires excavation to create a new neighborhood that complies with the City of San Francisco’s Better Streets Program and will accommodate increased housing density, community open spaces and improved accessibility. Westlake Urban’s proposed development includes realigning 5th Avenue to create a new neighborhood of up to 445 housing units. The project will also include community plazas, gardens, and stairways to view overlooks of the Pacific Ocean and Golden Gate Bridge. The project addresses the City’s dire need for additional housing near a major employer (UCSF) and public transit, but some neighbors have expressed concerns about the construction truck traffic related to the the new development.

The Kirkham Project’s Development Manager, Naomi Porat of Alpha Group, connected with Watershed Materials and coordinated an in-depth feasibility analysis to determine the environmental, economic, and community advantages of on-site block fabrication as a means to reduce off-haul. She commented, “Many of our developments require trucks to haul the excess excavated material to offsite locations. As a long-time entrepreneur in the green building and prefab industries, I was on a mission to find a sustainable solution for The Kirkham Project when I met David Easton of Watershed Materials. I suggested the idea of an onsite pop-up plant as a possible solution. The concept resonated with David Easton as a way to bring this innovative technology to construction sites. Our preliminary feasibility analysis at The Kirkham Project was extremely promising and we are now engaged in further analyses to prove the concept and confirm that the methods and technology will work for the project.”

The feasibility analysis involves the following steps:

Soil Testing: excavate 1’ - 5’ deep boring depth for Watershed Materials to test in its Napa lab then produce sample blocks and a report summarizing mix designs, compressive strength and density. The Kirkham Project site’s excavation proved ideal for producing masonry units using Watershed Materials’ high compression manufacturing process. Sample blocks were produced with a compressive strength of 2,905 psi, significantly greater than conventional CMU blocks. Identification of Site Elements for Block Utilization: The development team identified the site elements that could incorporate masonry blocks as the primary building material, including landscape pavers, pedestrian pavers, retaining walls, foundation and garages. Take-Offs & Total Block Estimate: The architect, engineer and landscape architect prepared rough take-offs of the elements for block material. The development’s contractor is providing detailed square footage estimates for Watershed Materials to determine the total block utilization potential at the site. Cost Estimates & Business Case: The final step in the feasibility analysis is to estimate the total cost of purchasing and installing the blocks as an alternative to conventional building materials for each of these estimates. In addition, the cost of setting up the pop-up facility and producing on site is incorporated into the total cost of the project, and compared to the cost of off-hauling and trucking new materials to the site.

The Kirkham Project development team, in collaboration with Watershed Materials, summarized the compelling advantages and potential challenges of the on-site fabrication facility and block integration in the project: