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HomeMy WebLinkAboutItem 25_Talbot Hill Arborist ReportPSE Talbot Hill Substation Arborist Report K:\project\31900\31983H\ProjectDocs\Reports\Talbot Hill Arborist Report.doc 11241 willows road ne suite 200 redmond, wa 98052 phone (425) 822-4446 Assignment The arborist report is required to accompany a Renton Site Plan Review submittal. It is developed to convey specific information regarding the trees proposed for removal, tree protection for trees to be retained and supplemental tree planting suggestions. I am coordinating the integration of tree removal, tree retention and tree protection into the landscape plans of the stormwater pond. Assessment Methods The inventory of trees was performed on October 13, 2016. The inventory is tabulated in the tree table which includes an assignment of tree number, identification of tree species by common and botanical names, diameter at breast height (DBH) measurement, a condition assessment using five categories (Excellent, Good, Fair, Poor and Dead) based on visual tree inspection of each tree, comments specific to each trees condition and the proposal to either remove or retain the tree. In the case of trees with multiple stems, typically beaked hazelnut trees in this case, I’ve noted the approximate number of stems and the stems average size. Site description The site address is 3004 Beacon Way South. The location of the subject trees is along the south side and southeast corner of the PSE Talbot Hill Substation. The land surface is undulating with vegetation typical of upland plant species. See figure 1. The majority of the trees are in good shape with the exception of the willow and alder; they have been damaged by recent branch failures during the spring windstorms. To: Jeff McMeekin, PSE From: Tom Early, Otak, Inc. Date: December 13, 2016 Project No.: 31983.h Jeff McMeekin, PSE Page 2 Talbot Hill Arborist Report December 13, 2016 K:\project\31900\31983H\ProjectDocs\Reports\Talbot Hill Arborist Report.doc Figure 1: google aerial showing substation area of selective tree removal on left, area of tree removal for storm water facility on right and direction of tree numbering Work proposed The work proposed is in association with improvements to the PSE Talbot Hill substation. A stormwater detention pond is proposed to be constructed to the southeast of the substation, see figure 1 above. The grading of the stormwater pond will require significant trees to be removed, see the tree table for a list of significant and non-significant trees to be removed. The removal of these significant trees requires a landscape planting effort to bolster the view buffer planting between the neighbors to the south and the substation to meet the Renton Municipal Code 4-4-070, specifically section F.4.c and H.6.c which call for fully sight obscuring landscape visual buffer. The execution of this planting to meet the letter and intent of the code is challenging in that the nearest location available for planting is between a maintenance road and the clearance zone of overhead transmission lines managed by Seattle City Light, see figure 2. In light of these constraints the fully sight-obscuring landscaped visual buffer is proposed to be 20 feet in width in two locations and contain a mixture of trees and large shrubs, some of which will mature to 35 feet tall. Jeff McMeekin, PSE Page 3 Talbot Hill Arborist Report December 13, 2016 K:\project\31900\31983H\ProjectDocs\Reports\Talbot Hill Arborist Report.doc Figure 2: view buffer planting areas and challenges with transmission line clearances and transmission line tower clearances We are also proposing to remove 11 significant trees to the west of the entrance driveway along the south side of the substation, see images 1 and 2. These trees are numbered 100 through 105, 108, 109, 113, 115 and 116. They are all Douglas fir trees. The majority of these trees are reaching a height in which their risk toward the substation is enhanced due to the prevalence of windblown limbs damaging equipment within the substation. The existing shrubs and smaller trees in this area are to remain to continue to provide their view buffer for the southern neighbors. Jeff McMeekin, PSE Page 4 Talbot Hill Arborist Report December 13, 2016 K:\project\31900\31983H\ProjectDocs\Reports\Talbot Hill Arborist Report.doc Image 1: proposed selective tree removals to reduce risk for substation, view from southeast corner of playfield looking to the north Image 2: view looking north-northeast from just north of 1507 Rolling Hills Avenue SE, dotted line indicates vegetation to remain and dashed line with transparent fill indicates vegetation to be removed Jeff McMeekin, PSE Page 5 Talbot Hill Arborist Report December 13, 2016 K:\project\31900\31983H\ProjectDocs\Reports\Talbot Hill Arborist Report.doc Tree protection recommendations Along with standard TESC measures, it is recommended that silt fence is used to mark the tree protection areas rather than duplicate the fencing required on-site. The silt fence should be placed at or outside of the trees dripline because it will need to be dug in to be correctly installed. In tree protection areas where silt fence is not proposed, 4 foot tall orange construction fence should be installed at the dripline or further from the trees to remain. This orange construction fence should be the same as the limits of disturbance. The area of proposed selective tree removals should not require tree protection fencing. Tree removals should be planned to control limb and main stem cuts to minimize damage to surrounding vegetation. Existing wildlife snags should be lowered in height to be less than their distance to the substation fence. Supplemental visual buffer plantings The visual buffer plantings include Vine Maple, Western Serviceberry, Beaked Hazelnut, California Wax Myrtle, Silk Tassel and Strawberry Trees planted at 6 feet triangular on-center spacing. The vine maple and western serviceberry are proposed to be 6 feet tall and the other plants are to be 5 gallon container at the time of installation. This visual buffer planting is 50% evergreen species to maximize the screening provided by the planting while also providing some variation to improve ecological services as well as aesthetics. Tom Early, Otak, Inc. Certified Arborist PN-5622A, Tree Risk Assessment Qualified Landscape Architect, Washington State # 1199 PSE Talbot HIll Substation Arborist Report Tree Table Trees at Stormwater Detention Pond Facility 1 of 4 Tree # Significant per RMC DBH Common Name Botanical Name Condition Comments Remove or Retain 1 Yes 10.5 Big Leaf Maple Acer macrophyllum Fair Remove 2 Yes 10.5 Big Leaf Maple Acer macrophyllum Fair Remove 3 Yes 12.5 Alder Alnus rubra Poor Remove 4 Yes 8 Alder Alnus rubra Poor Remove 5 No 4 Alder Alnus rubra Poor Remove 6 No 6 Alder Alnus rubra Poor Remove 7 Yes 12 Alder Alnus rubra Poor Remove 8 Yes 18 Alder Alnus rubra Poor Remove 9 No 6 Alder Alnus rubra Poor Remove 10 Yes 10 Alder Alnus rubra Poor Retain 11 Yes 28 Cottonwood Populus balsamifera Good Retain 12 Yes 6 Big Leaf Maple Acer macrophyllum Fair Retain 13 Yes 8 Big Leaf Maple Acer macrophyllum Fair Remove 14 No 5 Big Leaf Maple Acer macrophyllum Fair Remove 15 Yes 14 Alder Alnus rubra Poor Remove 16 Yes 10 Alder Alnus rubra Poor Remove 17 Yes 10 Alder Alnus rubra Poor Remove 18 Yes 10 Alder Alnus rubra Poor Retain 19 Yes 12 Alder Alnus rubra Poor Retain 20 Yes 10 Big Leaf Maple Acer macrophyllum Fair Remove 21 Yes 18 Douglas fir Pseudotsuga menziesii Fair sweeping trunk indicates fill placed while sapling Remove 22 Yes 13 Big Leaf Maple Acer macrophyllum Poor topped @12'Retain 23 Yes 29 Big Leaf Maple Acer macrophyllum Good Retain 24 Yes 6 Big Leaf Maple Acer macrophyllum Fair lost & regenerating main stem Retain 25 No 5 Big Leaf Maple Acer macrophyllum Good Retain 26 No 5 Big Leaf Maple Acer macrophyllum Poor lost main stem, regenerating with big natural sweep, suppressed by #23 Retain 27 Yes 6 Big Leaf Maple Acer macrophyllum Poor lost main stem regenerating with 3 acute attachments Retain 28 Yes 11 Beaked Hazelnut Corylus cornuta Good Retain 29 Yes 8 Big Leaf Maple Acer macrophyllum Fair Retain 30 Yes 14 Alder Alnus rubra Poor 10% live canopy ratio (LCR)Retain 31 Yes 13 Alder Alnus rubra Fair Retain 32 Yes 16 Alder Alnus rubra Dead currently a snag Retain 33 Yes 21 Douglas fir Pseudotsuga menziesii Good Retain 34 Yes 19 Douglas fir Pseudotsuga menziesii Good Retain 35 Yes 7 Beaked Hazelnut Corylus cornuta Good Retain 36 Yes 15 Douglas fir Pseudotsuga menziesii Good Retain 37 Yes 19 Douglas fir Pseudotsuga menziesii Good Retain 38 Yes 8 Pacific Dogwood Cornus nuttallii Good Retain 39 Yes 31 Douglas fir Pseudotsuga menziesii Good Retain 40 Yes 29 Douglas fir Pseudotsuga menziesii Good Retain 41 Yes 16.5 Douglas fir Pseudotsuga menziesii Good Retain 42 Yes 10.5 Pacific Dogwood Cornus nuttallii Fair thin canopy Retain PSE Talbot HIll Substation Arborist Report Tree Table Trees at Stormwater Detention Pond Facility 2 of 4 Tree # Significant per RMC DBH Common Name Botanical Name Condition Comments Remove or Retain 43 No 4.5 Beaked Hazelnut Corylus cornuta Good Retain 44 No 3 Beaked Hazelnut Corylus cornuta Good Retain 45 Yes 24 Douglas fir Pseudotsuga menziesii Good Retain 46 Yes 10.5 Douglas fir Pseudotsuga menziesii Fair lost leader, suppressed by tree #45 Retain 47 Yes 6 Big Leaf Maple Acer macrophyllum Good Retain 48 Yes 24 Douglas fir Pseudotsuga menziesii Good Retain 49 Yes 20 Douglas fir Pseudotsuga menziesii Good Remove 50 Yes 9.5 Willow Salix sitchensis Good Remove 51 Yes 11 Willow Salix sitchensis Fair 2 stems rising from failed stem on ground Remove 52 Yes 6 Willow Salix sitchensis Fair 10% LCR Remove 53 Yes 6 Willow Salix sitchensis Fair 10% LCR Remove 54 Yes 9 Willow Salix sitchensis Fair Access road clearance side-pruned Remove 55 Yes 8 Pacific Dogwood Cornus nuttallii Fair Canopy die-back and storm damage Remove 56 No 4 Beaked Hazelnut Corylus cornuta Good Remove 57 Yes 21.5 Douglas fir Pseudotsuga menziesii Good Remove 58 Yes 12.5 Douglas fir Pseudotsuga menziesii Fair Lost leader and suppressed by tree #57 Remove 59 No 5 Beaked Hazelnut Corylus cornuta Good Remove 60 Yes 26.5 Douglas fir Pseudotsuga menziesii Good Remove 61 Yes 20 Douglas fir Pseudotsuga menziesii Good Remove 62 Yes 21.5 Douglas fir Pseudotsuga menziesii Good Remove 63 Yes 17 Douglas fir Pseudotsuga menziesii Poor Included bark at base 3x stem diameter, suppressed by tree #64 Remove 64 Yes 33 Douglas fir Pseudotsuga menziesii Good Remove 65 Yes 32.3 Douglas fir Pseudotsuga menziesii Good Remove 66 Yes 24 Douglas fir Pseudotsuga menziesii Good Remove 67 No 3.5 Beaked Hazelnut Corylus cornuta Good Remove 68 Yes 26 Big Leaf Maple Acer macrophyllum Good Remove 69 Yes 42 Cottonwood Populus balsamifera Good Tree has reached maturity-sudden limb drop potential is high Remove 70 Yes 32 Cottonwood Populus balsamifera Good Suppressed by 42" cottonwood (#69), natural west lean 5°Remove 71 Yes 6 Beaked Hazelnut Corylus cornuta Good Remove 72 Yes 6 Beaked Hazelnut Corylus cornuta Good Remove 73 Yes 22 Alder Alnus rubra Poor Main stem die-back ~20%Remove 74 Yes 24 Alder Alnus rubra Fair Remove 75 No 6 Alder Alnus rubra Poor Suppressed by tree #74 Remove 76 No 6 Alder Alnus rubra Poor 15% LCR and upper canopy die-back Remove 77 No 6 Alder Alnus rubra Fair Remove 78 No 6 Alder Alnus rubra Fair Remove 79 No 6 Alder Alnus rubra Fair Remove 80 Yes 9 Alder Alnus rubra Fair Remove 81 Yes 12 Alder Alnus rubra Poor Dying Remove 82 Yes 18 Cottonwood Populus balsamifera Good Remove 83 Yes 18 Cottonwood Populus balsamifera Good Remove 84 Yes 7 Willow Salix sitchensis Poor Transmission line clearance pruned Remove PSE Talbot HIll Substation Arborist Report Tree Table Trees at Stormwater Detention Pond Facility 3 of 4 Tree # Significant per RMC DBH Common Name Botanical Name Condition Comments Remove or Retain 85 Yes 17 Willow Salix sitchensis Poor Transmission line clearance pruned Remove 86 Yes 8 Beaked Hazelnut Corylus cornuta Good Remove 87 No 5.5 Beaked Hazelnut Corylus cornuta Good Remove 88 Yes 11 Hawthorn Crataegus douglasii Fair Suppressed by 32" willow (#89)Remove 89 Yes 32 Willow Salix sitchensis Good Remove 90 Yes 8 Willow Salix sitchensis Poor Suppressed by 14" willow (#91)Remove 91 Yes 14 Willow Salix sitchensis Fair Canopy die-back and storm damage Remove 92 Yes 16 Willow Salix sitchensis Poor Storm damage to 30% of canopy Remove 93 No 6 Alder Alnus rubra Fair Remove 94 No 6 Alder Alnus rubra Fair Remove 95 Yes 8 Alder Alnus rubra Fair Remove 96 Yes 6 Willow Salix sitchensis Fair Remove 97 Yes 18 Willow Salix sitchensis Fair Remove 98 Yes 12 Willow Salix sitchensis Good Remove 99 Yes 14 Willow Salix sitchensis Poor Remove Total Significant Trees 80 Total to Significant Trees to Retain 28 Total to Significant Trees to Remove 52 PSE Talbot HIll Substation Arborist Report Tree Table Selective Tree Removal to Southwest of PSE Substation 4 of 4 Tree # Significant per RMC DBH Common Name Botanical Name Condition Comments Remove or Retain 100 Yes 23 Douglas fir Pseudotsuga menziesii Good Remove 101 Yes 19 Douglas fir Pseudotsuga menziesii Good Remove 102 Yes 8 Douglas fir Pseudotsuga menziesii Fair Suppressed by tree #103 Remove 103 Yes 25 Douglas fir Pseudotsuga menziesii Good Remove 104 Yes 11 Douglas fir Pseudotsuga menziesii Good Remove 105 Yes 24 Douglas fir Pseudotsuga menziesii Good Remove 106 Yes 20 Big leaf maple Acer macrophyllum Good Retain 107 Yes 23 Big leaf maple Acer macrophyllum Poor Topped @ 30'Retain 108 Yes 28 Douglas fir Pseudotsuga menziesii Poor Topped @ 50'Remove 109 Yes 20 Douglas fir Pseudotsuga menziesii Poor Two stems with union at 42" topped @ 50'Remove 110 Yes 16 Madrone Arbutus menziesii Good Retain 111 Yes 8 Pacific dogwood Cornus nuttallii Good Retain 112 Yes 8 Pacific dogwood Cornus nuttallii Good Retain 113 Yes 32 Douglas fir Pseudotsuga menziesii Dead snag that was topped @ 65' and still poses a risk to substation Remove 114 Yes 12 Douglas fir Pseudotsuga menziesii Dead snag Retain 115 Yes 24 Douglas fir Pseudotsuga menziesii Good Remove 116 Yes 16 Douglas fir Pseudotsuga menziesii Fair Suppressed by 24" Douglas fir (#115)Remove Total Significant Trees 17 Total to Significant Trees to Retain 6 Total to Significant Trees to Remove 11