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<br />~ COTTON, SHIRES & ASSOCIATES, INC. <br />.. CONSULTING ENGINEERS AND GEOLOGISTS <br /> <br />TO: <br /> <br />Marion Pavan <br />CITY OF PLEASANTON <br />Planning Department <br />200 Old Bernal A venue <br />Pleasanton, California 94566-0802 <br /> <br />July 12, 2006 <br />~~@~O~~[g) ROOll <br />JUL 2 1 Z006 <br /> <br />CITY OF PLEASANTON <br />PLANNING DEPT. <br /> <br />SUBJECT: <br /> <br />Supplemental Geologic and Geotechnical Peer Review <br />RE: Meadowlark (Austin Property) Development <br />Pleasanton, California <br /> <br />At your request, we have completed a supplemental geologic and geotechnical peer <br />review of the following document for the proposed residential development: <br /> <br />. Responses to Comments and Supplemental Recommendations, <br />Geologic/Geotechnical Investigation, Proposed Eight-Lot Meadowlark <br />Development, Foothill Road, Pleasanton, California, prepared by Berlogar <br />Geotechnical Consultants, dated June 14, 2006. <br /> <br />DISCUSSION <br /> <br />The letter referenced above is a response to our (Cotton, Shires and Associates, <br />Inc. - CSA) review letter dated June 9, 2006. The following section provides Berlogar <br />Geotechnical Consultants' (BGe) responses and recommendations to the issues discussed <br />in the June 9 review letter, and CSA review comments and recommendations. <br /> <br />CONCLUSIONS AND RECOMMENDED ACTION <br /> <br />1a. Stability of Older Landslide - BGC revised the 2003 stability analysis of the older <br />landslides using updated piezometric data as well as grading proposed on the <br />May 2006 grading plan. With raised water levels (3 feet higher than used in <br />2003), and with the proposed grading, the safety factor of the six surfaces <br />analyzed in 2003 decreased from 2% to 7%. The most critical surface (the same <br />surface critical surface found in the 2003 analysis) had a 2003 FS = 1.24, and a <br />2006 FS = 1.21. Based on these results, BGC believes the seismic displacements <br />estimated in 2003 of 0.75 feet to 4 feet will not change significantly, and the 150- <br />foot setback is still valid. <br /> <br />CSA Comment - The Project Geotechnical Consultant has adequately addressed <br />this issue. <br /> <br />Northern California Office <br />330 Village Lane <br />Los Gatas, CA 95030.7218 <br />(408) 354-5542 . Fax (408) 354'1852 <br />e.mail: losgatos@cottonshires.com <br /> <br />www.cottonshires.caDl <br /> <br />Central California Office <br />6417 Dogtown Road <br />San Andreas, CA 95249.9640 <br />(209)736-4252 . Fax (209)736-1212 <br />e-mail: cottonshires@starband.net <br />