O38 Email from Nov 13 2025 to Dec 9 2025 between Mr Kleinberg and Mr Seele

essentially i ignoring the presence of roots. Nonetheless, the FS indicates stability, and ‘reinforces your opinion that such an extraordinary analysis case of sloughing is unlikely to occur. 4. ACS as the designer of the Basins should, in our opinion, provide the evaluation to resolve the comment related to the impact of basin mounding on the slope. Langan performed the slope stability analysis using a design groundwater level that is higher in elevation in the soil and rock comprising the eastern slope than the high water level in the basins during any storm event. Because water in the basins cannot flow upward against gravity, there is no impact from mounding. I trust this satisfies your request. Mark Mark Seel Associate Principal / Vice President LANGAN Direct: 973.560.4986 Mobile: 724.263.2179 File Sharing Li www, langan.com Technical Excellence ¢ Practical Experience e Client Responsiveness NEW JERSEY NEW YORK CONNECTICUT MASSACHUSETTS PENNSYLVANIA VIRGINIA WASHINGTON, DC OHIO ILLINOIS NORTH GROuiNA. TENNESSEE FLORIDA TEXAS ARIZONA COLORADO UTAH WASHINGTON OREGON NEVADA CALIFOR ATHENS CALGARY DUBAI LONDON PANAMA From: Kleinberg, Sam <SKleinberg@cmeusal1.com> Sent: Friday, December 5, 2025 3:49 PM To: Mark Seel <mseel@langan.com>; pandersonpe@gmail.com Ce: MacNeill, Ryan <rmacneill@cmeusal.com>; Rizzo, Jordan <jrizzo@cmeusal.com>; Hernandez, Nelson <NHernandez@cmeusal.com>; Mazier, Alejandra <AMazier@cmeusal.com> Subject: RE: WEHI Hello Mark, Our initial comments are as follows: 1. A basis or reference should be provided for the selection of c=100 psf. For example see attached ref from “Biotechnical Slope Protection and Erosion Control” The values selected should be based on a representative estimate of the root area ratio. 2. The FS decreases quickly with depth. The analysis should, in our opinion be extended to at least 3 feet depth. 3. Based on our initial review safety factors of 1.2 would be appropriate for an extreme event.