August 13 2025, Planning Board Special Meeting Transcript - WEHI

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 20 Engineers, their manual, November 1994, it's EM, which is the engineering manual, 1110-1-2908, Engineering and Design Rock Foundations. I put a quote out here on Page 5 in the middle. "The calculated factor of safety is primarily dependent upon geometry of a potential failure as selected for analysis and the sheer strength representative of the potential failure surface. Other factors such as groundwater conditions and potential for erosion and seismic -- and highlighted -- I bolded this. The possible blasting use of the rock mass must also be addressed." The other thing they recommend, and it's on the second -- the bottom of the Page 5 is, "For major rock slopes where the consequence of failure is severe the minimum required calculated factor of safety is 2.0." So double what would be considered a just balanced at 1.0 where resisting factors -- resisting loads are equal to failure loads. But they recommend 2.0. "Other slopes that are not so consequential could be at a factor of safety as low as 1.3." However, based on my analysis and our understanding of the site and the proximity, especially the homes that are located literally on the toe of slope of Howell Drive, with those homes I would say that if there's a potential for damage to life of the property,