APPENDIX B. Arborist Report

Transcription

1 APPENDIX B Arborist Report

2 December 14, 2017 Prometheus Real Estate Group, Inc. c/o Jonathan Stone 1900 South Norfolk Street, Suite 150 San Mateo, CA Re: Arborist Report for 303 Baldwin Ave, San Mateo Dear Jonathan, The arborist report addresses the proposed project at 303 Baldwin Ave. Per the City of San Mateo s Heritage Tree Ordinance Chapter and the Planning Application Guide, the scope of work includes: Tag, identify, measure and assess trees over 6 in diameter; note size and species of trees smaller than 6. Note trees that are considered Heritage, defined as: o Any bay (Umbellularia californica), buckeye (Aesculus spp.), oak (Quercus spp.), cedar (Cedrus), redwood (Sequoia) tree with a diameter of 10 or more measured at 48 above grade. o Any tree or stand of trees designated by City Council to be of special historical value or of significant community benefit. o A stand of trees, the nature of which makes each dependent on the others for survival. o Any other tree with a trunk diameter of 16 or more, measured at 48 above grade. Identify dripline locations and tree numbers on site plan. Assess proposed improvements for potential encroachment. Based on proposed encroachment, tree health, structure, and species susceptibility, make recommendations for preservation. Provide values of all trees that will be removed, using the Existing Tree Evaluation Schedule with Landscape Unit Values worksheet. Site Summary The property is located in downtown San Mateo at the intersection of Baldwin Avenue and Ellsworth Avenue. Currently it is home to Trag s Market, with a parking lot wrapping around three sides of the existing building. On-site trees consist of small specimens (crape myrtle, windmill palm, hackberry) in parking lot planters. The proposed project will demolish existing structures to construct a 5-story mixed-use building, with two levels of underground parking spanning the entire property. All on-site trees will need to be removed, and all seven street trees near the property will be replaced with new trees. Four Monterey pines on the adjacent residential property are presently causing major hardscape damage in the 303 Baldwin parking lot. Since the proposed underground parking requires excavation at the property line, significant root pruning will occur adjacent to the trees trunks Cabrilho Drive Martinez, CA Telephone (925) Fax (925)

3 The anticipated root encroachment greatly increases likelihood of tree failure and/or death, so I recommend the trees be removed with permission from the owner. It is my opinion that all fifteen (15) trees will need to be removed to accommodate the proposed project. Assumptions & Limitations This report is based on my site visit on 11/28/17 and the preliminary planning package provided by WRNS Studio dated 8/16/17. It was assumed that the proposed improvements and trees were accurately surveyed on the plans. Tree locations on my plan were plotted referencing the survey provided by BKF Engineers, dated 12/12/16. The health and structure of the trees were assessed visually from ground level. No drilling, root excavation, or aerial inspections were performed. Internal or non-detectable defects may exist, and could lead to part or whole tree failures. Due to the dynamic nature of trees and their environment, it is not possible for arborists to guarantee that trees will not fail in the future. Tree Inventory & Assessment Table #s: Each tree was assigned a number from #39-53; all trees except the neighbor s were physically tagged with a square metal tag. Their locations are given in the tree protection plan. Size: Trunk diameters in inches were calculated from the circumference measured at 48 above average grade. Health & Structural Condition Rating Dead: Dead or declining past chance of recovery. Poor (P): Stunted or declining canopy, poor foliar color, possible disease or insect issues. Severe structural defects that may or may not be correctable. Usually not a reliable specimen for preservation. Fair (F): Fair to moderate vigor. Minor structural defects that can be corrected. More susceptible to construction impacts than a tree in good condition. Good (G): Good vigor and color, with no obvious problems or defects. Generally more resilient to impacts. Very Good (VG): Exceptional specimen with excellent vigor and structure. Unusually nice. Age Young (Y): Within the first 20% of expected life span. High resiliency to encroachment. Mature (M): Between 20% - 80% of expected life span. Moderate resiliency to encroachment. Overmature (OM): In >80% of expected life span. Low resiliency to encroachment. Heritage (H): trees considered heritage per city ordinance (see page 1) Jennifer Tso, Certified Arborist 2

4 # Species Size Health Structure Dripline N E S W Age H Comments Action 39 Hackberry (Celtis sp.) 9.5 F G-F M Street tree. Leaves have tip burn. Metal grate lifting out of planter. To be replaced with new street tree. 40 Hackberry 10 G-F F M Street tree. Metal grate lifting out of planter; roots growing over metal. To be replaced with new street tree. 41 Hackberry 10 G-F G-F M Street tree. Metal grate was removed and left on top of planter. To be replaced with new street tree. 42 Windmill palm (Trachycarpus fortunei) 18 G-F G M X 1.5' from adjacent crape myrtle. Trunk flush against curb of planter. Fronds have chlorotic spots. 7 clear trunk. In proposed building. 43 Crape myrtle (Lagerstroemia CV) 6.5 G G M In small parking lot planter. In proposed building. 44 Crape myrtle 6.5 G G M In small parking lot planter. Root crown covered by landscaping. In proposed building. 45 Hackberry 9 F F Y Planter curb raised 6" above adjacent sidewalk. Significant debris on sidewalk; sooty mold on remaining leaves. Slow to moderate growth. Leaf tip burn. Large girdling root around west side of tree. 6 from proposed building; in proposed patio. 46 Hackberry 10 G-F G-F M Street tree. Flush to metal grate; partially lifting up grate. To be replaced with new street tree. 47 Hackberry 10 F G-F M Street tree. Canopy shaped. Metal grate lifted by roots. To be replaced with new street tree. 48 Hackberry 10 F F M Street tree. Canopy shaped. Lifting metal grate, trunk is growing over edge of metal. To be replaced with new street tree. 49 Hackberry 9.5 F G-F M Street tree. Metal grate lifted. To be replaced with new street tree. Jennifer Tso, Certified Arborist 3

5 # Species Size Health Structure Dripline N E S W Age H Comments Action 50 Monterey Pine (Pinus radiata) 32 F-P F-P OM X Off-site, located at property line. Diameter estimated. Major flagging and tip dieback throughout canopy. Severe hardscape damage. Large co-dominant stems at 10. Proposed concrete paving up to trunk; proposed underground parking up to property line. High encroachment anticipated. Remove (requires owner s approval). 51 Monterey Pine 12 F-P F-P M Off-site, located at property line. Diameter estimated. 25% live crown ratio at best. Stunted and nearly suppressed by adjacent trees. Proposed concrete paving up to trunk; proposed underground parking up to property line. High encroachment anticipated. 52 Monterey Pine 32 G-F F-P M X Off-site, located at property line. Diameter estimated. Large co-dominant stems at 10. Minor flagging of branches. Severe hardscape damage; asphalt lifted nearly 1. Severe deformation of shared fence. Some scaffold branches topped with large vertical stems. Lifting up concrete slabs on apartment s side. Proposed concrete paving up to trunk; proposed underground parking up to property line. High encroachment anticipated. 53 Monterey Pine 18 G-F F-P M X Off-site, located at property line. Diameter estimated. Co-dominant stems at 10'. Significant hardscape damage. Shaded by adjacent pine. Proposed concrete paving up to trunk; proposed underground parking up to property line. High encroachment anticipated. Remove (requires owner s approval). Remove (requires owner s approval). Remove (requires owner s approval). Jennifer Tso, Certified Arborist 4

6 Discussion & Recommendations All on-site trees are located in the proposed building footprint or within the proposed patio area by the building. These trees will need to be removed to accommodate the proposed structure. Additionally, nearby street trees will be removed and replaced per City request. Four Monterey pines (50-53, Figure 1) were planted on the northwest neighbor s property, next to the shared fence. Two large pines (52, 53) are in good to fair condition, although they were planted too close together. Another large pine (50) is showing symptoms associated with pine pitch canker, such as flagging of branches throughout the canopy. The last pine (51) has remained small with a narrow canopy due to suppression by adjacent pines. The larger pines are close to peak maturity and have attained massive trunks. Since they were planted next to the property line, their trunks have pushed the fence out approximately 6. The roots are also massive, lifting the parking lot s asphalt surface nearly 12 by the largest pine. Since the proposed underground parking lot abuts the property line, all roots on the southwest side of the trees will need to be removed during excavation. The structural stability of the trees will be severely compromised, and the pines are likely to fall over and/or die. Figure 1. Monterey pines 50-53, planted next to property line fence. Large mature trees are typically worthy of saving due to their current and future benefits. However, Monterey pines are fairly short lived outside their native range (average years), and are highly susceptible to pine pitch canker and red turpentine beetle. (I was not able to inspect the trunks for red turpentine beetle, but large infestations can kill pines within a month or two.) They are also susceptible to drought stress and do not recover well. I do not consider the trees to be worthy of redesign efforts based on their longevity, susceptibility to stress and diseases, current structure and health, and location between two buildings. If saved, their canopies would also require a significant amount of clearance pruning that presents additional stress. Based on the proposed improvements, I recommend that all trees in the vicinity of the project be removed. This includes on-site trees, street trees, and Monterey pines on the adjacent property. Sincerely, Jennifer Tso Certified Arborist #WE-10270A Tree Risk Assessor Qualified Jennifer Tso, Certified Arborist 5

7 Figure 2 (Clockwise from top left) Pines # Flagging of branches is visible in canopy of #50. Trees appear to not have been maintained. Jennifer Tso, Certified Arborist 6

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