TO:
Honorable Mayor and Members of the City Council
THROUGH:
John Jalili, Interim City Manager
FROM:
Tony Olmos, Director of Public Works
Juan Price, Maintenance Superintendent
SUBJECT:Title
Submission of Citywide Street Tree Inventory And Tree Trimming Practices (Continued from the November 19, 2013, City Council Meeting) (Public Works Director Olmos).
RECEIVE REPORT AND PROVIDE DIRECTION
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Recommended Action
RECOMMENDATION:
Staff recommends that the City Council accept the citywide street tree inventory and direct staff to proceed with the development of a Street Tree Master Plan.
Body
FISCAL IMPLICATIONS:
Should the City Council direct staff to proceed with the development of a Street Tree Master Plan, staff will solicit proposals from qualified firms and will bring an agreement along with a proposed appropriation before City Council at a subsequent meeting.
BACKGROUND:
This report was continued from the November 19, 2013 City Council Meeting due to agenda length and time constraints.
As part of the 2013 Strategic Plan, Public Works was tasked with conducting an inventory of all City maintained trees. At the April 4, 2013, City Council meeting, City Council approved and awarded a three year tree trimming and tree inventory services contract to West Coast Arborists. During the meeting, staff received direction from City Council to include all street trees within the public right-of-way, including those currently maintained by adjacent property owners.
DISCUSSION:
WCA is a leading company in the arboriculture industry with expertise in tree trimming, tree inventories and preparation of urban tree master plans. As directed, WCA prepared a comprehensive Street Tree Inventory to include the following information:
- Total number of street trees, City and property owner maintained, cataloged by type, size, and condition
- Number of street tree candidate sites, i.e., vacant locations
- Trees recommended for removal and replacement due to structural or other defect
- Areas of existing or potential hardscape conflicts related to street trees
- Correlation of type of trees with hardscape conflicts
Street Tree Inventory
To highlight some key features, our GIS team has compiled several maps using the supplied data to demonstrate distribution patterns. Below is a brief overview of the attached graphics in the attachments:
Attachment A, labeled Tree Count and Findings, shows that there are 11,543 total trees in the public right-of-way. Of these, 4,173 are City maintained, the remaining 7,370 are maintained by adjacent property owners. There are 912 potential planting sites.
Attachments B, labeled Top Ten Tree Species shows the number and distribution of the ten most common tree species planted in Manhattan Beach.
Attachment C, labeled Top Hardscape Damage, shows trees with identified hardscape conflicts. These sites are showing some signs of hardscape displacement or visible cracking.
The information provided by the inventory is extremely valuable and will assist in:
- Assessing which tree species are appropriate for Manhattan Beach
- Provide a total inventory of the number, type, and current condition of City trees
- Identifies vacant sites as potential street tree installation sites
- Identifies candidate trees for replacement
- Identifies the number and location of trees most likely to cause sidewalk damage
- Accurately budget tree maintenance
- Chart a phased replacement program related to problematic street trees
All of this information is useful in assisting City leadership and staff in making data driven decisions concerning City trees.
Street Tree Master Plan
In addition to the inventory, the provided data is a necessary component in the development of a Citywide Street Tree Master Plan. Staff recommends the master plan should include the following elements:
- Recommend list of trees suitable for the climate and growing conditions in Manhattan Beach
- Address challenges associated with monoculture plantings versus mixed canopy strategies
- Recommend trees for specific conditions such as parkway width, soil condition, proximity to the ocean, and potential obstructions such as underground or overhead facilities
- Tree planting instructions for City staff, contractors, and developers
- A list of vacant street tree sites and recommended species to plant
- Tree maps by city maintenance district
- Review of the current street tree ordinance and suggested revisions
- A uniform tree pruning standard with instructions and parameters for proceeding with unique and/or non-standard situations
- Provisions for recurring maintenance costs associated with problematic trees
- Root pruning standards
- A fully developed maintenance program and refreshing of the tree inventory on a regular basis
- Review and recommend actions/guidelines regarding view obstructions
A Street Tree Master Plan and the included instructions would be of immediate value in working with City Maintained trees, but will prove invaluable should the City ultimately decide to actively manage all trees set within the City right- of- way in the future.
Hardscape Conflicts
The challenges associated with balancing risk, future repairs, and ongoing maintenance costs are intertwined with the City's street tree program. There is a direct link between street trees and hardscape conflicts within the City. Many City maintained trees are placed in tree wells, parkways or in close proximity to improvements. As trees mature, surface roots and general tree growth can cause many issues, mainly trip hazards. The canopies, if not managed properly over the life of the tree, can present traffic and pedestrian hazards due to lack of clearance or line of sight obstructions.
As sidewalk repairs are currently administered, adjacent property owners are responsible to maintain both trees and sidewalks. The City's annual sidewalk repair projects can sometimes become contentious due to resident responsibility for sidewalk and driveway repairs within the public rights of way. These issues are exacerbated in some instances due to multiple requests to make repairs to sidewalks or driveways while not allowing the removal of offending trees.
Many of the residential repair locations are adjacent to trees, and tree removal is sometimes required to safely make necessary repairs. Occasionally, large structural roots are removed and the tree is destabilized, and the tree must be removed for safety reasons. In spite of efforts to save trees from removal, structural deficits, facility damage or disease may not be discovered until the removal process is complete.
Tree Trimming Practice
Currently, City trees, excluding parkway trees, are trimmed on frequencies varying from one to three year intervals. Annual trimming usually includes palms, trees along Veterans Parkway adjacent to parking areas, Civic Center, and Streetscape. There are times a tree may require more or less trimming depending on species, individual growth habit, wind damage and proximity to pedestrians or vehicular traffic.
Questions have been raised regarding the City's decision to perform crown reduction and restoration to a number of trees in the Lot 8 parking lot. The trees that have been crown reduced are carrotwoods, and these trees have presented particular problems. West Coast Arborists was directed to perform the crown reduction to address the ongoing issued created by overcrowding. Recommended spacing is approximately 20 feet between specimens. When originally planted in circa 1990, the trees were small saplings and spaced from approximately 12 feet to as little as 6 feet center to center. Because of the close spacing, the canopies had become so thick as to stunt some trees. In 2013, 6 trees were removed from the area as they had completely been outcompeted by neighboring trees. Again, due to excessively close spacing, the interior of the trees had become very bare, and the trees have been growing in a distorted fashion, with branching becoming excessively long for the small caliper of the branches. Our observation and experience with this growth pattern is that when these cantilevered branches become fully leafed out and weighed down with fruiting bodies, breakage will occur.
When limb breakage occurs, it is often accompanied with large wounds and bark stripping. In addition to the wounding that often results from limb breakage, these trees are adjacent to a busy street and heavily used pedestrian pathway. In order to maintain the long term safety and health of the trees, the crown reduction and continuing crown restoration will ensure the long term health and appearance of the trees.
Crown reduction and restoration can be used judiciously in special circumstances to ameliorate the effects of spacing or location conflicts. The trees in Lot 8 will leaf out in short period of time, restoring a strong and aesthetically pleasing canopy.
CONCLUSION:
The City of Manhattan Beach possesses an urban forest consisting of 11,543 trees of varying species. Of these trees, approximately 36% are maintained by the City. The remaining 64% are maintained by adjacent property owners. 860 trees are identified as hardscape damaged, which constitutes approximately 7% of the current inventory.
Staff recommends that the City Council accept the citywide street tree inventory and direct staff to proceed with the development of a Street Tree Master Plan.
Attachments:
1. Tree Count and Findings
2. Top Ten Tree Species
3. Top Hardscape Damage