The campus landscape should adhere to the tenets of the 1909 Olmsted Plan, in order to maximize the plants' visual qualities and reinforce the campus organization and function.

Plant material selection, placement, and maintenance should focus on the appropriateness to the adjacent land use as well as the materials’ ability to reinforce the campus character.

  1. BACKGROUND
    1. Oregon State University’s historic campus core in Corvallis is based on a plan created in 1909 by the renowned Olmsted Brothers of Boston and is known as one of the most significant public landscapes in the State of Oregon. Its organization, harmony of materials, and maturity give it a sense of substantial quality. It is critical that future development maintain and expand upon the historic development patterns established by the Olmstead Plan and further refined by the Campus Master Plan, regardless of the scale of a campus improvement.
    2. In order to ensure that campus remains cohesive in character as it grows, each increment of growth should embody the qualities of the existing core. This approach requires consistency in the development of buildings and grounds and sensitivity to the scale and character of outdoor space.
    3. Campus streets provide the organizational framework for campus development. In addition to accommodating vehicular, pedestrian, and bicycle circulation, they provide tree-lined open space corridors through campus.
    4. Building placement is used to reinforce the open space corridors and quadrangles through uniform setbacks and sufficient spacing between structures. Primary outdoor gathering places, including courts, plazas, and gardens, are located near building entries.
    5. Quadrangles, framed by buildings, provide the primary usable open space on campus. They are strictly pedestrian oriented with walkways connecting building entries.  Pedestrian corridors link the quadrangles to the campus street grid and to other campus open spaces.

  2. PLANTING
    1. Organization
      1. The historic Olmsted pattern of planting should be reestablished and adapted to support current building uses and site requirements. As the campus core expands, planting should be of similar character to that of the historic core.
      2. Large deciduous trees planted in continuous and uniform rows (allées) should line campus streets.
      3. Primary open spaces such as quadrangles should be planted in open lawn framed and highlighted with large coniferous and deciduous trees.
      4. Plantings at building foundations should ideally respond directly to the adjacent architecture. Shrubs should not be taller than the building's visual base, or obscure the views from primary windows and entries. Shrub beds adjacent to the building should generally have widths approximately 20% of the building's height.
    2. Spatial Definition
      1. Plants should be used to define building entries, create outdoor space and assist in focusing pedestrian circulation.
      2. Plants alone will not deter pedestrian desire lines or provide significant barriers to circulation. Therefore, plants should be used in conjunction with good site design, effective circulation systems and other elements such as masonry walls.
    3. Planting Design
      1. Landscape design and components shall be planned for low ongoing maintenance requirements and reduced life cycle costs.
        1. Planting designs should specify plant species and varieties that are appropriate for the particular climate and growing conditions of the proposed planting location. Plants shall be grouped with like water requirements on same irrigation zone.
        2. Specialty plantings, including perennials, should occur primarily in courts and special gardens. Plants should be selected based on the University’s ability to maintain them.
        3. A clear space of at least 12” should be provided around all building foundations and foundation drains.
        4. The landscape plan and specified plant species shall be approved by the OSU FS Landscape Manager or designee prior to the acceptance of the landscape plan.
        5. Any changes to the plan requested by the OSU FS Landscape Manager or designee following a review of the plan shall be completed before final approval of the project will be granted.
      2. The landscape design must accommodate the mature size of the plants selected.
        1. Plant materials should remain appropriate in their location as they mature and reach ultimate size.
        2. Draft planting plans shall utilize plant symbols that represent the mature size of the specified plant material.
      3. The landscape design must accommodate fire department access to buildings at maturity.
        1. 36” of clear space must be provided around all hydrants and FDC connections at plant and tree maturity.
        2. The landscape design at maturity must allow for ladder truck access to the building.
      4. Continuous plantings of large street trees should remain a primary method of linking the campus together. Tree types and spacing should be consistent within large defined areas. Breaks in species should occur at significant intersections or where there is an obvious change in the character of the surrounding street or architectural context.
      5. Groundcovers, flowering trees, and deciduous and evergreen shrubs should be used primarily at the base of buildings to provide seasonal color and variation, reinforce the building's architectural style, and soften the building's bulk and mass.
      6. When adjacent to buildings, trees should be chosen and located to allow sun penetration to the building during the winter and shading during the summer.
      7. Tree plantings and replacements shall be coordinated with an Electrical Designer to avoid conflicts with exterior light poles.
      8. All landscape specifications shall meet or exceed the International Society of Arboriculture development guidelines for soil preparation and planting

  3. PLANTS
    1. Plant material must meet or exceed specifications documented in American Standards for Nursery Stock, ANSI Z60.1-2004, published by the American Nursery and Landscape Association.
    2. Plant material must be free of weeds in containers or root balls. Emerging weed infestations may be cause for rejection prior to planting or within the warranty period.
    3. Prohibited plants include all plants listed as noxious plants by the Oregon Department of Agriculture and the United States Department of Agriculture.
    4. Trees listed as prohibited street trees in Chapter 4.2 of the Corvallis Land Development Code shall be prohibited as street trees.  The Landscape Manager or designee may approve exceptions to this rule for locations on OSU-owned streets.
    5. All shrubs and trees must be labeled with original nursery I.D. tag and shall be true to form and description.
    6. An inspection point shall be provided for the project landscape architect or OSU FS Landscape Manager or designee to select or approve trees at:
      1. the nursery prior to digging
      2. arrival at project site
      3. plant layout and installation
    7. Trees shall be a minimum of 2” caliper.
      1. The OSU FS Landscape Manager or designee may grant an exception to the minimum size for unusual species, or availability.
      2. All trees smaller than 2” must be triple staked.
    8. Trees shall be planted in a manner consistent with standard Detail 1 -Tree Planting (See Diagram 32 80 00 Irrigation at end of the Section).
    9. Irrigation shall be provided as indicated in standard Detail 2- Tree Root Watering System (See Diagram 32 80 00BTree Root Warning System at end of this Section)

  4. TURF
    1. The minimum mowing equipment width is 60”. Turf areas must be designed to be maintained with this equipment.
    2. Seed shall be Perennial Rye grass blend.
    3. Perennial Rye grass blend may be substituted upon approval from the OSU FS Landscape Manager or designee.
    4. The allowable grass seeding period for OSU campus is March 15 through October 15, as soil conditions permit.  Planting outside of this period requires approval by the OSU FS Landscape Manager or designee.
    5. A minimum 10” wide concrete mow band shall be installed at finish grade adjacent to all structures. A minimum 20” wide mow band shall be installed beneath all fences.  Materials other than concrete may be approved by the OSU FS Landscape Manager or designee.
    6. No plastic or metal edging shall be permitted or used around planting areas to separate planting areas from lawn.

  5. SOIL
    1. The OSU FS Landscape Manager or designee shall determine if any existing top soil is suitable for reuse prior to the preparation of the landscape plan.
      1. The Designer shall contact the OSU Project Manager to receive approval to utilize the existing top soil in the landscape plan.
      2. All existing top soil approved for reuse shall be used to the greatest extent practicable.
    2. Separate top soil (maximum 18” depth) from subsoil during excavation and protect from contamination or compaction.  Stockpile and cover reserved soil at a location approved by OSU Project Manager and OSU FS Landscape Manager or designee.
    3. The Contractor shall protect existing topsoil and subsoil from compaction during construction.
      1. The Contractor is responsible for alleviating any and all unavoidable soil compaction before topsoil placement or irrigation system installation.
      2. Any mulch or base rock installed as part of the construction process or used to prevent soil compaction shall be removed from planting areas and turf areas prior to the placement of top soil.
    4. Imported soil is subject to OSU approval and shall conform to USDA soil texture class “loam” certified within one calendar year.
      1. Imported soil depth minimum when placed on subsoil is:
        1. 12” for turf areas with no trees.
        2. 24” for turf areas containing shrubs.
        3. 36” when placed over rock or fill materials.
        4. 36” minimum where trees are planted.
        5. Alternative imported soil depth may be proposed where there are site constraints subject to approval by OSU FS Landscape Manager or designee.
        6. Scarify subsoil and blend subsoil with first lift of imported soil. Install soil in 6” compacted lifts not to exceed 85%.
      2. The Contractor shall provide OSU a test sample for textural class determination prior to the installation any imported soil.
        1. The test shall be performed utilizing wet sieve soil texture analysis by OSU Central Analytical Lab or other OSU approved lab.
        2. Provide a minimum of two soil samples with the accompanying soil test report from samples obtained randomly throughout the source field location or stockpile.
        3. Submit approved test results at least four weeks prior to soil placement
    5. Athletic play areas may include USDA soil texture class sandy loam or other specified soil as approved by OSU FS Landscape Manager or designee.
    6. Soil must be free of contaminants and noxious weeds.
      1. If noxious weeds are present, Contractor shall eradicate following the guidelines in Pacific Northwest Weed Management Handbook or the recommendations of the Oregon Department of Agriculture. Control measures shall continue monthly on all emerging weeds for a period of one year from final acceptance.
    7. Incorporate organic matter homogeneously throughout the planting area.
    8. Remove all rock from planting areas prior to topsoil placement.
    9. Provide an inspection point for project landscape architect or OSU FS Landscape Manager or designee for:
      1. subsoil preparation;
      2. irrigation installation and as-built mark-ups before covering with soil; and
      3. topsoil/amendment incorporation and finish grades.

  6. SOIL VOLUMES
    1. All trees shall be provided with the minimum available soil volume required to support healthy tree and tree root growth at maturity. 
      1. The minimum required available soil volume shall be determined using the canopy diameter of the selected species at maturity and Figure 32 90 01- Soil Volume Chart below.
      2. To be considered available, soils:
        1. must be within a 50’ radius of the tree’s trunk;
        2. must not be growth limiting soils; and
        3. must be directly connected to the tree by a continuous path that is 3’ in depth and a minimum 3’ in width.
      3. In locations where soil testing has determined that growth limiting soils are present, to count as available soils, tree growth limiting soils must be either:
        1. removed and replaced to a depth of 3’ with imported soils that meet the standards for imported soils listed above; or
        2. amended to a depth of 3’; method to be determined by OSU FS Landscape Manager or designee.
    2. The required available soil volume may be provided in open soil areas or in covered soil areas.
      1. Open soil areas are unpaved areas within a 50’ radius of the tree.
        1. To be considered available soil volumes, open soil areas must meet the criteria for available soil volumes listed in Section 32 90 00 6.A.ii.
        2. Open soil volumes shall be calculated (in cubic feet) by measuring the open soil area (in square feet) times a demonstrated soil depth of 3’.
      2. Covered soil areas are soil areas within a 50’ radius of the tree that are under pavement.
        1. To be considered available soil volumes, covered soil areas:
          1. must meet the criteria for available soil volumes listed in Section 32 90 00 6.A.ii, and
          2. must be part of a tree well installation that meets the criteria listed in Section 32 90 00 7.
        2. Covered soil volumes shall be calculated (in cubic feet) by measuring the covered soil area (in square feet) times a demonstrated soil depth of 3’.
        3. Where covered soils volumes are used to meet the minimum soil volume requirements the following shall apply:
          1. Paving constructed over covered soil volumes shall be reinforced or supported to prevent settlement and cracking of the paving (i.e. vehicle-rated concrete, reinforced concrete, soil cell systems, grid systems, structural soil, permeable/porous paving systems).
          2. Soil compaction shall be limited to 85% for standard soils or 98% for structural soils.
    3. All trees shall be provided with a minimum open soil area measuring at least 6’ by 6’, surrounding the trunk of the tree.  OSU standard tree grates may be used within this area. Refer to Detail 32 90 00 7.D Tree Grate Detail.  Alternate proposals may be used if approved by the OSU Project Manager and the OSU FS Landscape Manager or designee.
    4. The available soil volume for a tree shall be calculated by adding the available open soil volume (per Section 32 90 00 6.B.i) to the available covered soil volume (per Section 32 90 00 6.B.ii). Calculations shall be made in cubic feet.
    5. Soil volumes are considered “available” to a tree only when demonstrated to be available by the soil volume plan and associated details. (See Diagram 32 80 00 Required Soil volume to Canopy/Trunk Diameter Ratio at end of this Section).

  7. TREE WELL PLANTING STANDARDS
    1. A tree well is an assembly of materials used to create a tree planting area that provides the required minimum available soil volume to promote healthy tree and tree root growth in locations where the minimum available soil volume cannot be provided in open soil areas
    2. Trees shall be planted in tree wells
      1. when covered soil volumes are necessary to provide the required available soil volume, or
      2. when trees are planted along streets and tree wells are required per Corvallis Land Development Code Chapter 3.36.
    3. Tree wells shall conform to the following standards:
      1. Trees shall be provided the minimum soil volume required for the selected species’ canopy diameter as shown in Figure 32 90 01 - Soil Volume Chart .The canopy diameter of the selected species at maturity should be used.
      2. Paving constructed over covered soil volumes shall be reinforced or supported to prevent settlement and cracking of the paving.
        1. Vehicle-rated concrete, reinforced concrete, soil cell systems, grid systems, or other hardscape systems may be used.
        2. Systems or techniques for tree well design not listed above may be used if approved by the OSU Project Manager and the OSU FS Landscape Manager or designee.
      3. Soil compaction shall be limited to 85% for standard soils or 98% for structural soils.
      4. Irrigation shall be provided as indicated in standard Detail 2 - Tree Planting.
    4. Where tree grates are required or specified, an OSU standard tree grate shall be used: (See Diagram 32 80 00 Tree Grate at end of the Section).  Alternate tree grates may be used if approved by the OSU Project Manager and the OSU FS Landscape Manager or designee.

  8. SOIL VOLUME PLAN REQUIREMENTS
    1. A soil volume plan shall be required for any tree to be planted if a covered soil volume is proposed to be used to meet any portion of the minimum available soil.
    2. The soil volume plan shall be reviewed and approved by the OSU Project Manager and the OSU FS Landscape Manager or designee.
    3. A soil volume plan shall be developed by a registered landscape architect that includes all of the following elements:
      1. Date of drawing or last revision;
      2. North arrow;
      3. Bar scale;
      4. Site address or assessor’s parcel number;
      5. The name, address, telephone number, email address and license number of the project landscape architect;
      6. The location of property lines;
      7. The location of proposed building footprints, utilities and irrigation, streets and other paved areas;
      8. The assigned numbers of all street trees to be planted, corresponding to the soil volume calculation table;
      9. The location of each open soil volume area and each covered soil volume area considered “available” for each tree; and
      10. A table showing the soil volume calculation for each street tree to be planted.

 

Diagram 32 80 00A Tree Planting Detail


 


 

Diagram 32 80 00B Tree Root Watering System 


 


Diagram 32 80 00C Soil Volumne


 


 

Diagram 32 80 00D Tree Gate Detail

Last Updated: 
07/31/2018