1920 GRAND AVE 2016-01-01 MF Import

hardpan. Runoff is described as rapid, the available water capacity is low, and the hazard of�nrater erosion is moderate to hioh Xerorthents are described as areas where the surface layer, subsoil and substratum have been greatly disturbed, removed or replaced with other material. Properties of these areas can vary greatly within short distances, and should be examined by a geotechnical engineer to determine on-site capabilities. Tree Condition Eva/uaHon For this assessment, the above ground poRions of the remaining standing trees were examined in accordance with the protocol and methodology contained in Evaluation of Hazard Trees in Urban Areas (Matheny and Clark, 1994). No inspection of beluw- ground portions of the trees were performed for this report. The inspection also included visual examination of stumps on the steep slope (as viewed from above) and examination of the cut trees, which remain on the property. The trees inspected are primarily big-leaf maple, and range from approximately 13"-22 diameter at breast height (DBH). Standing trees exhibit a spread of approximately 30' and a height of approximately 50-80'. DBH, height and spread of cut trees is di�cult to determine. Based on the size of the downed logs, the cut trees are within the same size range as the remaining trees. Virtually all the big-leaf maple cut on the site exhibit interior decay, which can be seen both on the remaining stumps and on cut logs remaining on-site (see enclosed photos). This condition is very common in big-leaf maple, and frequently Ieads to limb breakage and tree failure. The amount of decay present (based on a visual examination) ranges from 10-40°h. In addition, from the position of remaining stumps and uncut trees, it is apparent that trees on the slope were leaning significantly downslope, towards the railroad tracks. Big-leaf maples with interior decay and leaning growth are at a high risk of failure, from both breakage and windthrow. Conclusion and Recommendadons In order for trees to present a hazard, two components must be present. There must be a tree with the potential to fail, and a target (person or�tructure) that would be injured or damaged by the failing tree. Both components are present in this situation. The trees removed from and remaining on the slope were/are leaning and the remaining trees are likely to suffer from the same internal decay as the cut trees, considering they are the same species and are approximately the same age. A target (the railroad line) is also present within range of many of the trees on the slope. The target cannot be moved, and is subject to frequent use. The remaining trees which are leaning or are over 8" DBH present an unacceptable risk of damage to life and property in this situation, and should be removed. In addition, there is one remaining Douglas fir at the north end of the top of the slope that has been topped or damaged at some point in the past. The tree currently has multiple central leaders, and likely has interior decay from the wound to the crown (similar to the cut Douglas fir). This tree is in close proximity to an existing residence, and will be in close proximity to the proposed development on-site, and is recommended for removal. It is recommended that the big-leaf maple stumps be left in the ground, to avoid disturbance to the unstable soils on the slope and to provide some additional stzbilization by the presence of live roots. It is likely that many of the big-leaf maple � �3