Street Magnolia - Regulated Tree. Before working in this area contact City Arborist at 650-496-5953
CITY OF PALO ALTO
TREE TECHNICAL MANUAL STANDARDS AND SPECIFICATIONS
SECTION 2.00 - PROTECTION OF TREES DURING CONSTRUCTION Size and type of fence
All trees to be preserved shall be protected with five or six (5’ - 6’) foot high chain link fences. Fences are to be mounted on two inch diameter galvanized iron posts, driven into the ground to a depth of at least 2-feet at no more than 10-foot spacing (see Public Works Department Detail #505, Appendix K). This detail shall appear on grading, demolition and improvement plans.
5.45 WATERING SCHEDULE
Newly installed trees planted, including drought tolerant species, are dependent upon supplemental irrigation until established, typically for two years. Periods of extreme heat, wind or drought may require more or less water than recommended in these specifications. The method and amount that is applied may vary depending upon soil composition, heat, wind, planted in turf or ground cover, periods of abnormal rainfall or in poorly drained soils (see Drainage, Section 3.40-C). The watering of protected or designated trees or their replacements shall follow these standards:
A. New trees
During the establishment period (1-2 years) trees should be watered thoroughly to their root depth as frequently as needed. A watering schedule is to be submitted at the preconstruction meeting. The schedule is to include watering frequency and quantity. The minimum standards shall be as follows:
1-3 months in the ground: 4 times per month or as necessary
4-6 months in the ground: 2 times per month or as necessary
7-12 months in the ground: 1 time per month or as necessary
B. Mature trees
Most species: 1 time per month during irrigation season (usually March through September) Coast Live Oak, Valley Oak and Blue Oak: deep water in May and September — do not water during other months. For oaks already in the vicinity of irrigated conditions, automatic sprinklers or regular
watering shall not be allowed to spray on or within three feet of the trunk. The water shall not be allowed to pool or drain towards the trunk.
C. Watering Methods
The following options shall fulfill the watering requirements. One or more of the following may be utilized dependent upon unique circumstances subject to the City Arborist determination. The options are as follows:
1. Automated Watering Systems. All new street trees planted within the right-of-way and designated trees shall be provided with one of the following automatic watering systems. All tree irrigation is to be consistent with current Landscape Water Efficiency Standards for the City of Palo Alto. Other city maintained systems shall be per Parks Department specifications. notes: Bubbler heads (Preferred). One or two bubbler heads mounted on flexible tubing are to be placed adjacent to or on top of the root ball. The placement of bubbler within an aeration tube is not allowed.
Drip Loop system. A continuous loop of drip tubing circling around the trunk at a point two-thirds out from the trunk to the edge of the root ball (for new trees 36-inch box size and greater, a second loop of drip tubing is required at a point just beyond the root ball on native soil).
Hand watering systems. Recommended for trees that are part of a development project that must be watered to insure tree survival during the course of construction until automatic irrigation is installed.
Flood watering. Newly installed trees must be ‘flood or basin watered’ on top of the root ball to allow the water to infiltrate through the root zone.
Subsurface injections using a hydraulic spray pump (practical for use in hard, compacted soils or steep hillsides).
Soaker hose. Slow, deep watering using a garden type soaker hose.
Wetting agent. A root ball that has been allowed to dry out beyond the wilting point shall require the addition of a wetting agent to the water (such as Aqua-grow or equivalent).
Unless otherwise specified, the volume of water applied at each irrigation should be in the range of 10-gallons per inch of trunk diameter when measured at 54-inches above natural grade. The final decision of whether to water or not should be based on accurate soil probe samples that are taken from the root ball.