15 ATTACHMENT 9 - Laserfiche WebLink

Project No. 9929.G Response to Peer Review/I630 Vineyard Ave., Pleasanton, CA 12 March 2007 Evaluation of Suspected Landslide in Vicinity of Proposed Lot 6 Based on landslide mapping by Nielson (1975), AKA identified a landslide on the southeast side of the property in the vicinity of proposed Lot 6. To evaluate the presence or absence of the suspected landslide identified by AKA, we reviewed published geological work, performed a field reconnaissance and excavated two test pits (TP-1 and TP-2}. Based on a review of the Nielsen maps, it appears that the entire slide or the majority of the slide is off site to the adjoining Heinz property. It appears that the northerly extent of the mapped slide is along a small ridge that trends the length of the southeast property line. The test pits were excavated to determine if landslide deposits are present within lot 6. No evidence of landsliding was observed in either test pit. A strike and dip was obtained in TP-2 (N30W/24NE) that coincides with Livermore Gravel bedding. This is generally similar with bedding orientations on the Preliminary Geologic Map of the Livermore Quadrangle mapped by Dibblee (1980) and the orientations of the bedding measured in test pit, TP-3. At the time of our test pit fieldwork in May 2004, the neighboring property to the southeast, (Heinz property) was being graded and based on discussions with a representative of Engeo Incorporated, the geotechnical engineer of record for the development, no landslide mitigation measures were being performed in the area of question. It is our opinion the mapped slide does not exist on the subject site. Based on discussions with the property owner, Mr. Sarich, the pond was present when he purchased the property in February 2000, and since that tune has never observed any seepage in the pond area. Based on his observations, the water that collects in the pond is due to runoff during the rainy season and the pond is dry generally for 8 to 9 months of the year. At the time of our site visits, seepage in the pond was never observed. The aerial photos reviewed in reference 1 are as follows; 5/5/78 1: l 2,000 AV ] 498-02-15/17 8/18/88 1:12,000 AV 3368-27-45/46 It is anticipated that the pond will be removed as part of the development, however, the final grading plans are not available. Should the pond be removed, the pond embankment and any