20 ATTACHMENT 3 - Laserfiche WebLink

Updated Arborist Report HortScience I Bartlett Consulting Sarvana Chilla, 3987 Stanley Page 6 to be installed 10' to the west of the tree. The concrete driveway is 20' to the south and 20' to the west of the oak. In order to retain the tree, I recommend the following design changes: • No grading within 10' of the tree. • No grass to be installed within 10' of the tree. Low drought -tolerant plants that thrive in shading conditions could be considered. • No subsurface irrigation lines should be installed within 10' of the tree. • The use of gravel is acceptable for the driveway, however only when used over a biaxial geogrid material as the subgrade layer below aggregate. • The pavement section needs to be built up on top of existing grade so that no excavation occurs within the tree's root zone within the driveway area. Trees #11-15 were located on the northern property line. All were windmill palms and outside of impacts. However, there should be no grade change within 5' of the base of the trees. Trees #10 and 16 are outside of impacts. Tree #17 is an off-site valley oak with a canopy extending 5' onto the property. Tree #19 is an off-site walnut tree. The walnut had a canopy that extended onto the property by 9'. Care will need to be taken to prevent damage to the walnut tree canopy extending over the driveway from construction equipment. Based on my assessment of the plan, I recommend removing eight trees. One tree (#4) was in poor condition including one of the eight trees that would be impacted by construction. One tree (#6) recommended for removal qualifies as a Heritage tree. The following two trees need special considerations: • Following the recommendations, including the utilization of the biaxial Geogrid under the gravel on the driveway to the west of the tree will allow for preservation of valley oak #18, which qualifies as a Heritage tree. • Approach the neighbors about the future plans for off-site tree #1. This tree need to be protected against impacts from construction equipment and the new driveway. Preservation is recommended for nine trees, including two off-site trees (#17 and 19). These two trees (#17 and 19) qualify as Heritage trees. Trees recommended for preservation are located along the perimeter of the site or on the edges of the building envelopes. In summary, a total of eleven trees (#1, 10 - 18 and 19) can be retained and two are Heritage trees. One valley oak tree (#18) is a Heritage tree. Eight trees are within impacts and will need to be removed. One of the trees to be removed (#6) is a Heritage tree. Specific preservation requirements are provided in the Tree Preservation Guidelines. Appraisal of Value The City of Pleasanton requires that the value of trees to be preserved during construction be established and included as part of an Arborist Report. To establish the value of the trees, I employed the standard methods found in Guide for Plant Appraisal, 9th edition (published in 2000 by the International Society of Arboriculture, Savoy IL). In addition, I referred to Species Classification and Group Assignment (2004), a publication of the Western Chapter of the International Society of Arboriculture. These two documents outline the methods employed in tree appraisal. The value of landscape trees is based upon four factors: size, species, condition and location. Size is measured as trunk diameter, normally 54" above grade. The species factor considers the adaptability and appropriateness of the plant in the East Bay. The Species Classification and Group Assignment lists recommended species ratings and evaluations. Condition reflects the health and structural integrity of the tree at the time of my inspection. The location factor considers the site, placement and contribution of the tree in its surrounding landscape.