22 ATTACHMENT 02 - Laserfiche WebLink

• Introduction Assignment Berlogar Geotechnical Consultants (BGC) requested Ralph Osterling Consultants,Inc. s` (ROC) to complete a tree assessment report of certain trees located on property adjacent to Silver Oaks Court. This report is limited to 21 trees called out by BGC and an additional four trees ROC observed to be possibly relevant to the project. Survey Methods A visual assessment of the trees was made from the ground. No samples were collected for laboratory analysis nor were the trees climbed as neither were part of the assignment. The trees were affixed with blue numerical aluminum tags for reference purposes in the report and the Tree Location Map. The numerical tags were affixed on the north facing side of the trunk approximately five to six feet above grade when physically possible. The trunk diameter of trees was measured with a diameter tape at the height of 4.5 feet above ground level as specified in Chapter 17.16 'Tree Preservation',section 17.16.006 'Definitions' of the municipal code for the City of Pleasanton Observations and Discussion On 22 September 2010,ROC visited the subject property to complete the requested tree assessment. The property was observed to be former pasture land and without residential structures. Mature blue oaks are the dominate tree species. A total of 25 trees composed of 3 tree species were assessed;blue oak (23),black oak (1) and valley oak (1). Please refer to Table 1 -Summary of Tree Species for additional information. The subject trees were assessed for structure, health and overall condition. Table 2- Evaluation Factors for Determining Overall Tree Condition defines the characteristics for each rating. Table 4-Tree Assessment Chart includes the condition ratings for each assessed tree. Two trees,both blue oaks were observed to have suffered major limb failures. Tree 6 lost approximately one third of its canopy with its limb failure. The failed limb remains attached to the trunk and appears stable. One half of the canopy for tree 8 was lost with its limb failure. Debris and the failed limb were removed from the vicinity of tree 8. A large crack is visible from the face of the wound extending to the base of the tree. Assessed trees were also rated as to suitability for preservation. Nineteen trees were rated high in suitability for preservation and six were determined to be moderate in suitability for preservation.