As required by the Federal Aviation Administration (FAA), the flight path to Moffett Federal Airfield must be clear of encroachments.  The City of Sunnyvale has been notified by NASA Ames Research Center that the 2005 biannual survey of the flight path airspace corridor indicated that twelve City Coast Redwood street trees were encroaching into the Moffett Field flight path and that these trees must be either pruned or removed.

Staff evaluated the trees in question and determined that height reduction pruning was the least expensive as well as the least environmentally and aesthetically objectionable.

This height reduction pruning would be considered a new service and is not currently funded in the Street Tree Services program.  Due to service level reduc­tions implemented in FY 2003-04, the Street Tree Services program does not have the staff or equipment to perform the required high pruning on these redwood trees.  Staff recommends that this work be contracted.  The estimated cost including a fifteen percent contingency is $16,675.

To maintain compliance with FAA regulations these redwood trees will require ongoing pruning every third year.  The ongoing funding of the required tree pruning will be included in the Budget review cycle for FY 2006/07.

BACKGROUND

In April 2005 the Street Tree Services program manager was notified by the Operations Engineer at NASA Ames Research Center – Moffett Federal Airfield, regarding Moffett Airfield flight path requirements.  Nasa informed the City that it was required by Federal Aviation Administration (FAA) regulations to survey the Moffett Field flight path for compliance to clearance standards every two years.  

As a result of the survey (See attachment A – Tree Site Listing) for 2005, twenty-five (25) Coast Redwood trees were identified as encroaching into the flight path airspace.  Of the twenty-five trees identified, twelve (12) Coast Redwood trees have been identified as being in the public right-of-way (ROW) and by default are City street trees. The remaining trees are off the ROW and are on private property. The trees on private property are the responsibility of the private property owners.       

EXISTING POLICY

The Land Use and Transportation Element comments on Moffett Federal Airfield.  Chapter 2, Community Conditions (p 57) states:

“Moffett Federal Airfield: Since the adoption of the Moffett Field Comprehensive Use Plan, there have been ongoing discussions regarding the potential uses of the Moffett Federal Airfield.  The City of Sunnyvale supports the continued federal ownership and operation of this facility.

The City will closely monitor any changes to the status of Moffett Federal Airfield.  The City will also continue to exert its influence to achieve the best outcome for the community.”

Community Development Element Section 2.5 – Community Design Sub-Element identifies desirable roadside features which include:

Goal 2.5B Create an attractive street environment which will compliment private and public properties and be comfortable for residents and visitors.

Policy 2.5B.1 Maintain and provide attractive landscaping in the public right-of-way to identify the different types of roadways and districts, make motorists more comfortable and improve the enjoyment of residential neighborhoods.

Action Statement 2.5B.1j.  Continue to plant and maintain street trees along the public right-of-way and identify areas which require replanting or replacement trees.

DISCUSSION

There are 1,023 Coast Redwood, Sequoia sempervirens, street trees in Sunnyvale, approximately twenty-five of these trees are in locations that are, or have the potential to grow into FAA regulated airspace. The redwood trees that have been identified by NASA Ames are on Benicia and Mary Avenues, south of the Sunnyvale Golf Course.

Of the twenty-five redwood street trees identified as encroaching into the Moffett flight path airspace, twelve of them are in the City right-of-way (ROW.)   The other thirteen redwood trees encroaching in the flight path are located on private property.  The private redwood trees are the responsibility of the individual private property owners to prune or remove in order to comply with FAA and PUC requirements

California PUC Code Sections 21655‑21660 (See Attachment B – CA PUC Regulations) pertain to the FAA requirements.  Code Section 21659 states that "No person shall construct or alter any structure or permit any natural growth to grow at a height which exceeds the obstruction standards set forth in the regulations of the Federal Aviation Administration relating to objects affecting navigable airspace".  The trees which have been identified by the 2005 NASA Ames survey as encroaching into the Moffett fight path airspace present a safety issue for aircraft and a liability issue for the City of Sunnyvale. 

The city arborists have evaluated this situation and have determined that the least expensive and the least environmental objectionable is to prune the affected redwood trees to such heights to remove the encroachment hazard.  Removal and replacement of the redwood trees with alternate, lower growing species was evaluated.  It was determined that even though redwood is a desirable wood species and would have a relative high value, the cost of removal in a urban setting exceeded the wood value.  Aesthetically and environmentally the removal of these redwood trees would negatively impact the community.

The redwood trees requiring height reduction for FAA regulation compliance range from ninety-nine to one hundred sixteen feet tall.  The height reductions required vary depending on the location of the tree.

The Street Tree Services program does not prune city street trees for height reduction.  Therefore, the height limit pruning for certain redwood trees on Benicia and Mary Avenues is a new service.  This is the first time that staff is aware of any street tree in Sunnyvale encroaching into the Moffett Federal Airfield air space.

With the Coast Redwood trees requiring height reduction being at or over one hundred feet tall, the current city equipment and staff are unable to prune at such heights.  Because of these inabilities the height reduction pruning is recommended to be contracted.

From staff experience with Coast Redwood trees and their growth and regrowth habits, redwood trees that have had their apical leader removed will resprout with many sprouts.  The growth of each of these sprouts is relatively short, one to two feet per year.  It will take approximately three years to grow five to six feet.  To maintain compliance with FAA regula­tions these redwood trees will require ongoing pruning every third year.

The original removal of ten to thirty feet of these redwood trees will require more effort and care than subsequent pruning.  The vegetative regrowth on these redwoods will be relatively small compared to the original pruning.

There are also trees on the Sunnyvale Golf Course that are in the Moffett flight path that also require pruning.  These are separate from the current 25 identified in need of pruning.  These city trees at the golf course that require pruning are on the portion of land owned by the United States of America and leased to the City of Sunnyvale. (See Attachment C – Parcel Map SV Golf Course North of Hwy 237)  As part of the lease agreement between the City of Sunnyvale and NASA Ames Research Center (See Attachment D – Golf Course Lease Agreement) per Article 5(b) NASA shall have the right to, and shall, trim trees below a height it determines necessary in order to facilitate safe operation of Moffett Federal Airfield.  Staff was informed by the Operations Engineer at NASA Ames Research Center that because there were so few trees on the City owned side in this area that it would be more expeditious for NASA to include the work to be done with no cost to the City as part of NASA’s tree trimming flight path clearance work. Trees outside of the Sunnyvale Golf Course are not maintained by NASA Ames.

Council approval of Budget Modification No. 15 would appropriate the required funds to complete the pruning requirements for this fiscal year.  The pruning of the Coast Redwood street trees will be done as soon as possible after Council approval.  The ongoing funding of the required tree pruning would be included in the Budget review cycle for FY 2006/07.

FISCAL IMPACT