. Timothy C. Ghirardelli C O N S U L T I N G A R B O R I S T S E R V I C E S Timothy C. Ghirardelli Consulting Arborist Services 1200 Mt. Diablo Blvd., Suite 204 Walnut Creek, CA 94596 Phone 925.899.8090 Southern Magnolia Tree Evaluation & Tree Protection Plan St. Mary s Catholic Church 2039 Mt. Diablo Blvd., Walnut Creek, CA June 11, 2015.......... Sustainable Solutions in the Urban Interface Since 1980 Certified Arborist #WE 0704 A
Southern Magnolia Tree Protection Plan St. Mary s Church, Walnut Creek 6/11/2014. Summary & Introduction I have been retained by St. Mary s Church to provide an evaluation of one 28-inch diameter Southern Magnolia tree (Magnolia grandiflora) to establish tree health and the suitability for retention within the proposed construction environment. This tree is measured at 54-inches above grade. My review is provided pursuant to guidelines defined in the Walnut Creek Municipal Code, Chapter 8, Ordinance No. 1966 that mandates protection for any project that affects existing trees to be retained. My review of the site occurred on June 9, 2014. The proposed project includes adding a new chapel and removing an existing building to accommodate the plan. The design proposal also includes a bioswale plan with parking and traffic flow reconfiguration adjacent to the tree. I have reviewed the Parking Lot Improvement Plans sheets 1-7 by DK Consulting. I have not reviewed Grading, Drainage, Landscape or Utilities plans. The Magnolia tree is healthy and suited to the long term. Leaf size and color are good. Tree vigor and canopy density appears good to excellent. There are no harmful pests or diseases at the time of my review. I ve had the opportunity to work with the design team to minimize adverse affects to tree health by eliminating four parking stalls on east and west sides of the tree and minimizing grading within the protected tree canopy. In my opinion, with the idea of additional efforts to further adjust parking lot elevations, this tree will likely undergo moderate and sustainable impacts depending on root discovery and avoidance during construction. Long term tree sustainability however will depend directly on application of the Tree Protection Plan provided. The following pages contain my review and the Tree Protection Plan. Timothy C. Ghirardelli CONSULTING ARBORIST--WC ISA CERTIFIED ARBORIST WE #0704 A 2
Southern Magnolia Tree Protection Plan St. Mary s Church, Walnut Creek 6/11/2014. Discussion Primary contributing elements to current tree health include the existing wooden deck that and surrounding fencing that protects the critical root zone within the tree canopy. The deck serves to protect tree roots from foot traffic that compacts soil and suffocates roots over time. The deck and fencing also serves to maintain cooler soil temperatures that allow roots to thrive. Minimizing disturbance of this area throughout construction is central to the long term health of the tree. Based on 10-ft. property boundary set-backs and proposed Chapel size, design limits mandate the 25-foot minimum distance needed for the parking lanes north side of the tree adjacent to the Chapel. The current design configuration results in grading and root loss at approximately 5.7 from the trunk of tree to the face of curb. DK Engineering states ground elevation is 174.69 where the curb is proposed with 173.39 as bottom of the AB layer. This would result in a roughly 15-inch cut below existing ground elevations. DK Engineering indicates that these elevations could be adjusted to further accommodate tree roots if needed. Raising parking lot elevations within the tree canopy area to accommodate the root zone would reduce tree impacts. Additionally reducing the thickness of the AB layer by 50% or 6-inches would also reduce root loss. Preliminary visual review of buttress roots on the north side of the tree are smaller in size than their east, west and south sides indicating proportionally fewer root zone impacts. And although aggressive root cutting is proposed on the north side, grading and root zone disturbances on the other three sides are minimal within the protected tree canopy. The proposed bioswale located on the south side of the tree is 9-feet wide and 6-feet deep at the lowest point with sloping sides. The bioswale begins approximately 20-feet from the trunk of tree approximately 3-feet beyond canopy edges with the deepest point approximately 6-feet away. The bioswale design will allow root migration into the system to symbiotically manage surface water and benefit the tree. The Landscape Plan should incorporate the Magnolia tree into the bioswale design as a single feature and include limited planting within the tree canopy area. 3 Timothy C. Ghirardelli Consulting Arborist 925.899.8090
Southern Magnolia Tree Protection Plan St. Mary s Church, Walnut Creek 6/11/2014. Construction Impact Evaluation Most nutrient and water absorbing roots that sustain the tree can be found in the top 6 to 12 inches of soil. Raising or lowering grades just 4 to 6 inches, or trenching and compacting soils with equipment within natural tree canopies will all affect tree health and longevity. Construction impact ratings are intended to serve as a guideline for evaluating the long term sustainability of trees as a result of impacts. Trees are evaluated to determine the potential impact of construction relative to their location on the site plan. Tree impact ratings are estimated and limited to the plan set provided. The rating system measures to canopy edges to establish the critical root zone. Viewing canopy edges as one hundred percent of the critical root zone, proposed impacts are rated in percentages of root loss to the critical area. The more root loss that occurs to a tree, the less it will be able to survive. Tree species, age, health and vigor influence impact ratings. High Impact Trees in the High Impact category are considered to be at, or beyond the maximum range of root loss for that specimen. Trees in this category are unlikely to sustain the proposed impacts for the long term. A significant change in the proposed plan is required in order to retain the tree. Specific recommendations are required from the Arborist to reduce proposed impacts. Grade cuts, fills and/or alterations that result in root loss to 30% and greater of the critical root zone. Moderate Impact Trees in the Moderate Impact category are considered to be within the range of sustainable root loss for that specimen. Trees in this category undergo alterations that require specific recommendations from the Arborist to reduce proposed impacts. Grade cuts, fills and/or alterations that result in root loss to less than 30% of the root zone. Low Impact Trees in the Low Impact category are considered to be well within the acceptable range of root loss for that specimen. Trees in this category may require specific recommendations from the Arborist to reduce proposed impacts. Grade cuts, fills at canopy edges or beyond and/or supervised alterations within the canopy. 4 Timothy C. Ghirardelli Consulting Arborist 925. 899.8090
Southern Magnolia Tree Protection Plan St. Mary s Church, Walnut Creek 6/11/2014. Tree Protection Plan A. The proposed plans for demolition and construction at St. Mary s Church call for canopy encroachments that have the potential to directly affect tree health. This Tree Protection Plan is provided to mitigate impacts to the tree that will occur as a result of proposed alterations. B. Any tree to be retained within the construction envelope will require the following prescribed treatments prior to, during and after construction activities. A good working relationship between the Arborist and contractor and a clear understanding of contractor issues relative to arboricultural issues is essential to avoid any debilitating tree damage. C. The Project Arborist shall be on site for each phase where alterations occur within the canopy of trees selected to remain. 48-hour advance notice is required prior to any approved alterations within the canopy of protected trees. Summary tree protection guidelines to navigate with the Project Arborist: 1) Pre-construction: Prior to any alterations, review the site with the Project Arborist prior to alterations to identify specific site limitations such as vehicle access and material handling and equipment storage. Review specific methods needed to retain the tree selected to remain. Discuss protective tree fencing within the limits of the site that are also sustainable to the tree. 2) Grading: Raising or lowering grades within the protected tree canopy is the single most destructive process to the tree. Retain the Project Arborist prior to grading to monitor all grading activities. 3) Trenching: Severing roots can destabilize tree structure and result in rapid decline. Retain the Project Arborist prior to trenching for all underground activity to monitor construction and implement root protection procedures. 4) Landscaping: Any landscape plantings proposed within the canopy of the existing tree shall require review. Trenching for irrigation, hardscape construction and the installation of incompatible plants can be just as traumatic to tree health as any of the above can be. Retain the Project Arborist prior to planting, trenching for utilities or drainage to monitor construction activity and implement root protection procedures. 5
Tree Protection Plan Broadway Plaza Walnut Creek 6/11/2014 1. Root Zone Protection Prior to, and During Construction 1.1 Prior to any approved demolition or construction activity, assign a confined, dedicated area for material and equipment storage away from the established tree canopy and the immediate project area. 1.2 Remove the existing wooden deck by hand under Project Arborist direction. Leave existing leaf litter within the canopy as possible to maintain natural conditions. 1.3 To be determined--apply a 4 to 6 inch layer of mulch to the available root zone within the protected tree canopy to reduce soil temperatures, maintain soil moisture and soil fertility. 1.4 Under the direction of the Project Arborist, install chain-link fencing or approved equal at canopy perimeters prior to any demolition, grading or construction to establish and maintain the Tree Protection Zone (TPZ). 1.5 Install a small, closable 24-36-inch wide serviceable access point into the protected tree canopy area. 1.6 Fencing shall be a minimum of 6-feet high with 2-inch diameter steel posts on 8-10-foot centers driven directly into the ground. 1.7 Pursuant to City of Walnut Creek Guidelines, attach a weather proof sign, minimum 8.5-inch x 11-inch with the wording Tree Protection Zone-This fence shall not be removed without prior approval of the Project Arborist-a violation of this order shall result in a stop work order. Include contact name and number. 1.8 Prior to the start of construction, install/supply a dedicated surface-installed irrigation line to maintain adequate soil moisture and alleviate stresses from root loss. The irrigation system shall consist of ¾ inch Schedule 40-PVC with the capable water pressure to deliver up to 4 spray heads designed to cover the protected root zone. The irrigation system shall be placed on a (battery or electric) controller and timed as necessary by the Project Arborist. The irrigation system may be incorporated into the permanent landscape design. 2 Root Pruning Prior to Grading 2.1 Hand paint to mark the ground where approved grade cuts are to occur for Curbs, Parking surface and Bioswale at canopy edges for Project Arborist review. Hand trench under Project Arborist direction exposing roots to the depth of grade cuts. Cut all roots up to 2- inches in diameter by hand using loppers and hand saws. Roots larger than 2-inches in diameter shall be cut with a chain saw. 3. Pruning Prior to Demolition & Construction 3.1 Any pruning and clearance work directly related to demolition and construction shall occur under Project Arborist direction prior to construction. 3.2 All pruning shall be completed by approved Certified Arborists familiar with the most recent editions of the American National Standard for Tree Care Operations (Z133.1) and Pruning (A-300) and Best Management Practices for Pruning published the International Society of Arboriculture. 6
Tree Protection Plan Broadway Plaza Walnut Creek 6/11/2014 4. Landscape Construction 4.1 Planting shall remain no closer than 10-feet from the tree trunk. Plants shall be 1 to 5 gallon in size, drought tolerant, and compatible with the tree. 4.2 Planting pits shall be dug by hand and avoid disturbance of roots 2-inches in diameter and greater. 4.3 Rototilling, soil disturbance or import soil shall not occur within the protected tree canopy. 5. Hand Trench Conduits, Electrical, Plumbing, Drainage 5.1 All underground conduits planned within 5-feet of the protected tree canopy shall be hand trenched or rerouted under Project Arborist direction. No underground conduits shall be routed within the protected tree canopy. Hand trenching leaves roots 2-inches and larger undisturbed. Soil is removed from under and around tree roots to form the necessary trench. 5.2 Roots larger than 2-inches may only be removed with the approval of the Project Arborist. 5.3 Roots less than 2 inches must be pruned with loppers or hand saw. 6. Arborist s Supplemental Reports 6.1 Submit supplemental reports to satisfy City of Walnut Creek requirements to be determined: 1- The Project Arborist s observations of the site; 2. Any and all work that was performed in the Tree Protection Zone; 3. Recommendations for future work and monitoring to include washing off foliage, pest or disease problems and treatments. 6.2 At Project Completion--Verify compliance with the City of Walnut Creek and Project Arborist s Tree Protection Plan requirements and any additional recommendations. 7
June 30, 2015 St. Mary s Catholic Church 2039 Mt. Diablo Blvd., Walnut Creek, CA RE: ADDENDUM TO ARBORIST REPORT DATED JUNE 11, 2014 The following revisions to the Arborist Report dated June 11, 2014 are provided pursuant to the subsequent City comments letter dated June 18, 2014. The exhibit on the following page defines Tree Protection Zone. Superseding revisions are provided to the Tree Protection Plan in the earlier June 11, 2014 document. Elements of improvement over the last submittal influencing tree health are directed to the following: Grading at the north side of the Magnolia tree: The proposed building elevations limit flexibility of curb elevations with respect to drainage. However engineering was able to marginally adjust elevations reducing the vertical cut below grade to 173.80 versus the previous 173.39. Hand trenching at the face of cut to observe roots as directed in the enclosed Tree Protection Plan will provide direction to the necessary mitigation. Bioswale size reduction: Four fewer parking spaces removed from within the tree canopy allow a reduction in bioswale size. Engineering is reportedly able to adjust the size of the bioswale at the south side of the tree and concentrate the size reduction at the edges of the tree canopy rather than over the larger design. Design elements are in-process and I have not reviewed updated plans that show this modification. Timothy C. Ghirardelli CONSULTING ARBORIST WC ISA CERTIFIED ARBORIST WE #0704 A Page 1 of 5 Sustainable Solutions in the Urban Interface Since 1980 1200 MT. DIABLO BLVD.,, SUITE 204, WALNUT CREEK, CA 94596 PHONE (925) 899.8090
Tree Protection Zone Page 2 of 5
Tree Protection Plan A. The proposed plans for demolition and construction at St. Mary s Church call for canopy encroachments that have the potential to directly affect tree health. This Tree Protection Plan is provided to mitigate impacts to the tree that will occur as a result of proposed alterations. B. Any tree to be retained within the construction envelope will require the following prescribed treatments prior to, during and after construction activities. A good working relationship between the Arborist and contractor and a clear understanding of contractor issues relative to arboricultural issues is essential to avoid any debilitating tree damage. C. The Project Arborist shall be on site for each phase where alterations occur within the canopy of trees selected to remain. 48-hour advance notice is required prior to any approved alterations within the canopy of protected trees. Summary tree protection guidelines to navigate with the Project Arborist: 1) Pre-construction: Prior to any alterations, review the site with the Project Arborist prior to alterations to identify specific site limitations such as vehicle access and material handling and equipment storage. Review specific methods needed to retain the tree selected to remain. Discuss protective tree fencing within the limits of the site that are also sustainable to the tree. 2) Grading: Raising or lowering grades within the protected tree canopy is the single most destructive process to the tree. Retain the Project Arborist prior to grading to monitor all grading activities. 3) Trenching: Severing roots can destabilize tree structure and result in rapid decline. Retain the Project Arborist prior to trenching for all underground activity to monitor construction and implement root protection procedures. 4) Landscaping: Any landscape plantings proposed within the canopy of the existing tree shall require review. Trenching for irrigation, hardscape construction and the installation of incompatible plants can be just as traumatic to tree health as any of the above can be. Retain the Project Arborist prior to planting, trenching for utilities or drainage to monitor construction activity and implement root protection procedures. Page 3 of 5
1. Root Zone Protection Prior to, and During Construction 1.1 Prior to any approved demolition or construction activity, assign a confined, dedicated area for material and equipment storage away from the tree canopy and the immediate project area. 1.2 Remove the existing wooden deck by hand under Project Arborist direction. Leave existing leaf litter within the canopy as possible to maintain natural conditions. 1.3 To be determined--apply a 4 to 6 inch layer of mulch to the available root zone within the tree canopy to reduce soil temperatures, maintain soil moisture and soil fertility. 1.4 Establish the Tree Protection Zone--Under the direction of the Project Arborist, install chain-link fencing or approved equal at canopy edges where no grading is to occur prior to any demolition, grading or construction to establish and maintain the Tree Protection Zone (TPZ). 1.5 Install a small, closable 24-36-inch wide serviceable access point into the protected tree canopy area. 1.6 Fencing shall be a minimum of 6-feet high with 2-inch diameter steel posts on 8-10-foot centers driven directly into the ground. 1.7 Pursuant to City of Walnut Creek Guidelines, attach a weather proof sign, minimum 8.5-inch x 11-inch with the wording Tree Protection Zone-This fence shall not be removed without prior approval of the Project Arborist-a violation of this order shall result in a stop work order. Include contact name and number. 1.8 Prior to the start of construction, install/supply a dedicated surface-installed irrigation line to maintain adequate soil moisture and alleviate stresses from root loss. The irrigation system shall consist of ¾ inch Schedule 40-PVC with the capable water pressure to deliver up to 4 spray heads designed to cover the protected root zone. The irrigation system shall be placed on a (battery or electric) controller and timed as necessary by the Project Arborist. The irrigation system may be incorporated into the permanent landscape design. 2 Construction outside the TPZ Inside the tree canopy 2.1 ROOTS-Prior to grading at the north side of the tree, hand trench at face of cut to expose roots to be pruned under Project Arborist direction. Spray paint ground to identify the area where approved grade cuts are to occur for curbs, parking surface and bioswale. 2.2 Expose roots to the depth of proposed cut. Prune roots as directed: 2.3 Cut all roots up to 2-inches in diameter by hand using loppers and hand saws. Roots larger than 2-inches in diameter shall be cut with a chain saw. 2.4 CLEARANCE PRUNING-Perform overhead clearance pruning as directed in Section 3 on the following page. 2.5 GRADING AND FILL MATERIALS-minimize compaction of the AB layer without mechanical vibration to allow a more favorable root zone environment and subsequent root migration into the new material. Page 4 of 5
3. Pruning Prior to Demolition & Construction 3.1 Any pruning and clearance work directly related to demolition and construction shall occur under Project Arborist direction prior to construction. 3.2 All pruning shall be completed by approved Certified Arborists familiar with the most recent editions of the American National Standard for Tree Care Operations (Z133.1) and Pruning (A-300) and Best Management Practices for Pruning published the International Society of Arboriculture. 4. Landscape Construction 4.1 Planting shall remain no closer than 10-feet from the tree trunk. Plants shall be 1 to 5 gallon in size, drought tolerant, and compatible with the tree. 4.2 Planting pits shall be dug by hand and avoid disturbance of roots 2-inches in diameter and greater. 4.3 Rototilling, soil disturbance or import soil shall not occur within the protected tree canopy. 5. Hand Trench Conduits, Electrical, Plumbing, Drainage 5.1 All underground conduits planned within 5-feet of the protected tree canopy shall be hand trenched or rerouted under Project Arborist direction. No underground conduits shall be routed within the protected tree canopy. Hand trenching leaves roots 2-inches and larger undisturbed. Soil is removed from under and around tree roots to form the necessary trench. 5.2 Roots larger than 2-inches may only be removed with the approval of the Project Arborist. 5.3 Roots less than 2 inches must be pruned with loppers or hand saw. 6. Arborist s Supplemental Reports 6.1 Submit supplemental reports to satisfy City of Walnut Creek requirements to be determined: 1-The Project Arborist s observations of the site; 2. Any and all work that was performed in the Tree Protection Zone; 3. Recommendations for future work and monitoring to include washing off foliage, pest or disease problems and treatments. 6.2 At Project Completion--Verify compliance with the City of Walnut Creek and Project Arborist s Tree Protection Plan requirements and any additional recommendations. Page 5 of 5