1. Purpose: The purpose of this Section 11-04-09 is to establish requirements for the design, installation, and maintenance of landscapes that:
A. Conserve, protect and promote the City's natural environment and high quality of life;
B. Contribute ecologically and aesthetically to the prosperity of the City;
C. Achieve healthy, attractive, and safe environments based on recognized design and urban forestry principles;
D. Expand the tree canopy to reduce the heat island impact and mitigate climate impacts;
E. Improve pedestrian comfort;
F. Conserve water;
G. Integrate stormwater management and minimize polluted water;
H. Screen the visibility of less desirable uses and functions;
I. Preserve native vegetation and the appropriate use of native landscape materials; and
J. Reduce adverse impacts to wildlife.
2. Applicability: All applications for development or property use listed below shall comply with the provisions of this Section 11-04-09.
A. Development:
(1)
All new development involving the construction of new Multiple-Family Dwelling, mixed-use, and nonresidential buildings. Residential uses with four or fewer units in a single structure are exempt from these standards.
(2) The expansion and alteration of the gross floor area of an existing Multiple-Family Dwelling, mixed-use or nonresidential building by 50 percent or more.
B. Compliance With Existing Approvals Required: If an application under this Code does not otherwise require a change to the existing landscaping, fencing, walls, or screening on the lot or parcel, but the existing development is not in compliance with the landscaping, fencing, walls, or screening required by a previous permit or approval for that development, the City may require compliance with the terms of those prior approvals as a condition on the approval of the current application.
C. Existing Parking Lots:
(1) When existing parking lots are re-striped or a new coat is applied to the surfacing, the applicant shall replace and repair the existing landscaping to the standards that applied at the time the related building was constructed or the related use began operations.
(2) When the area of an existing parking lot is replaced or is expanded up to 25 percent, the applicant shall replace and repair the existing landscaping to the standards that applied at the time the related building was constructed or the related use began operations and shall install parking lot perimeter landscaping that complies with Section 11-04-09
.5.B(3).
(3) When the area of an existing parking lot is expanded by 26 percent or more, the applicant shall comply with all standards in this Section 11-04-09
regarding parking lot landscaping.
3. General Landscaping Standards:
A. Landscape Plan Required: A landscape plan is required for all activities subject to this Section 11-04-09, regardless of whether the application is for a Zoning Certificate, Certificate of Appropriateness, Conditional Use Permit, Variance, or Minor or Major Design Review.
B. Adopted Streetscape Plans: Where the City has adopted streetscape standards for any street bordering a project site, and there is a conflict between the adopted streetscape standards and the standards of this Section 11-04-09, the adopted streetscape standards shall apply.
C. Site Area Landscaping:
(1) Any part of a site not used for buildings, parking, driveways, walkways, utilities, or approved storage areas shall be retained or reclaimed to its natural state such that it is free of dust and noxious weeds or landscaped pursuant to the standards in this Section 11-04-09.
(2) Plants, walls, fences, buffering, and screening, located on adjacent properties do not satisfy landscape requirements for the subject property. All required landscaping shall be located on the property required to provide it pursuant to this Section 11-04-09.
(3) An approved protective curbing shall be required adjacent to all planting areas that border driveways, parking lots or vehicle use areas.
(4) If the location of any utility facility, utility easement, or service area required by adopted City or utility provider standards prevents the location of trees, shrubs, or other landscaping in locations required by this Section 11-04-09, the applicant shall be required to install an equivalent numbers of trees, shrubs, or landscaping in other landscaped areas of the site. If the required number of trees cannot be accommodated on the remaining available site area, the applicant shall satisfy the mitigation requirements under Section 11-04-09.8, Tree Preservation.
D. Landscape Material Standards:
(1) Approved Plant Materials:
(a) The latest edition of the Treasure Valley Tree Selection Guide, or any successor publication as determined by the Director of Parks and Recreation, is hereby adopted as the list of approved and recommended trees for on-site planting.
(b) Plant selection, establishment, and maintenance for storm water facilities shall comply with the Public Works Department Stormwater Plant Materials Resource Guide to the maximum extent practicable.
(c) New plant varieties are being produced every year and other species not listed in the above publications or species that are more disease resistant, pest resistant, or drought tolerant may also be approved by the Director of Parks and Recreation.
(2) Prohibited Plant Materials: The plants listed as Trees Not Permitted for Rights-of-Way Property Planting in the Treasure Valley Tree Selection Guide are prohibited from being planted along any street or within any parking lot subject to this Section 11-04-09.
(3) Minimum Plant Sizes:
(4) Plant Species Diversity:
(a) Trees: When five or more trees are to be planted to meet the requirements of any portion of this Section, a mix of species shall be provided as shown in Table 11-04.16
below:
(b) Other Plant Materials:
i. To improve pollinator habitat, at least 25 percent of planted areas shall include native flowering and nectar producing plant species.
ii. Where shrubs are required to be planted, up to 25 percent of the total number of required shrubs may be substituted with flowering perennials, grasses, or ferns.
(5) Non-Vegetative Materials:
(a) Non-vegetative materials, such as decorative rock, artificial grass, bark, and perma-bark, shall not count toward the minimum landscape requirement.
(b) The use of bark or other loose material shall be designed and located to prevent being displaced or washed out of the planting area.
(c) Non-vegetative material, including but not limited to rock mulch and decorative rock, may only be used to augment the landscape or around the base of trees and shrub groupings or flower beds, and shall not constitute the only ground cover in more than 20 percent of any area required to be landscaped.
(d) Planting areas using rock mulch or decorative rock shall have 50 percent of the ground surface covered by vegetation at plant maturity.
(e) Natural colors shall be used.
(6) Mulch:
(a) Organic mulch such as bark or soil aid shall be applied and maintained in all planting areas at a minimum two-inch depth, except that decorative rock mulch may be permitted as part of the approved landscape plan.
(b) Use of mulch as the only ground cover in required planting areas is prohibited.
(c) Impermeable plastic weed barrier under the mulch is prohibited.
E.
Water Conservation Standards: All required landscaping shall be designed to address the physical site characteristics of the property, the needs of those using the property, and the best water-conserving methods for a semi-arid continental climate. The landscape plan shall reduce water consumption through site design, plant selection, irrigation practices, and improved soil water holding capacity through amendment with compost, complying with the following xeriscaping and conservation standards:
(1) Soil Amendment: Prior to the installation of lawn or other plant materials in areas that have been disturbed or compacted by construction activity, soils shall be amended to increase soil water holding capacity. Proper soil amendment includes thoroughly loosening soils to a depth of six inches, adding compost as a soil amendment at a rate of four cubic yards per 1,000 square feet of total area to be planted, and thoroughly incorporating compost to a depth of at least two inches. Areas with existing native vegetation that remain undisturbed shall be exempt from the soil amendment requirement, provided that native soil and vegetation in such area is protected from disturbance and compaction during the construction process.
(2) Lawn Areas:
(a) Lawn areas shall be a drought-tolerant and/or adaptive sod or seed mix that is appropriate to the natural conditions found at the site, except that lawn species that require regular mowing or maintenance, such as Kentucky Bluegrass:
i. Shall not exceed 33 percent of the landscaped area on a site; and
ii. Shall not be used in median strips, parking strips, or difficult-to-maintain areas less than six feet in width.
(b) Lawn areas larger than 15,000 square feet shall have soil moisture sensors that are properly installed and adjusted.
(c) In all zoning districts, any area that does not provide recreational value or is used solely for decorative purposes is prohibited from using lawn that requires regular maintenance for landscape purposes. This prohibition includes but is not limited to the installation of Kentucky Bluegrass turf in roadway medians, traffic circles and roundabouts, street frontage areas located between detached sidewalks and curbs, and within parking lot landscaped islands or stormwater swales. Low ground cover alternatives shall be used to the maximum extent practicable.
(3) Plant Selection, Plant Location and Efficient Irrigation:
(a) Plants shall be placed based on adaptability to regional and micro climatic conditions, including shade, sun, and wind.
(b) Plants having similar water needs shall be grouped together in distinct hydrozones and spaced to minimize watering needs while maximizing growth and spread of plants.
(c) Native and other low-water-use plants shall be installed to the maximum extent practicable.
(d) Invasive, destructive, and exotic plants shall not be installed.
(4) Water Features: Water features such as fountains, waterfalls and ponds are discouraged, but if used shall comply with the following standards:
(a) The water used shall be recycled through the feature;
(b) The feature shall be designed to prevent leakage;
(c) Provisions for continued maintenance of the feature shall be identified in a narrative that accompanies the landscape plan; and
(d) Evidence of the right to use the water for this purpose is required when the water will be obtained from an irrigation ditch or a well.
F. Placement and Installation of Trees:
(1) Location and Spacing: All trees planted pursuant to this Section 11-04-09 shall comply with the following standards. Class I, II, and III trees are identified in the Treasure Valley Tree Selection Guide.
(a) For every 60 feet of perimeter landscape, one Class III tree shall be planted.
(b) Class III trees shall be spaced 40 to 50 feet apart, depending on mature crown spread.
(c) Class II trees may be used and spaced 25 to 45 feet apart, depending on mature crown spread.
(d) Class I trees shall be used where overhead power lines prohibit use of taller trees and may be used to mark entry points into a subdivision or to mark a special feature.
(e) Class I trees shall be spaced 15 to 30 feet apart, depending on mature crown spread.
(f) For design flexibility, trees may be grouped together or spaced evenly as desired. Unless Community Forestry approves an alternative spacing, trees shall be spaced no closer than 80 percent of the average mature width of the trees as demonstrated in the following examples:
(2) Curbing to Protect Tree s: All planting areas that border driveways, parking lots and other vehicle use areas shall be protected by curbing, wheel stops, or other protective devices located a minimum of 30 inches from all tree trunks.
(3) Avoiding Interference with Utilities: The following standards apply to the planting of trees near existing utilities and to trenching for new utilities near existing trees:
(a) Overhead Utilities: Class I may only be planted under or within 10 lateral feet of any overhead utility wires if approved by Community Forestry.
(b) Underground Utilities:
i. All trees shall be planted outside of any utility easement, unless written approval is obtained from the applicable agency.
ii. All trees shall be planted outside of any easement that contains a City sewer main, unless written approval is obtained from the City Engineer.
iii. If any utility easement precludes trees required by this Section, the width of the required buffer shall be increased to accommodate the required trees.
(c) Trenching: New underground utilities shall be located outside of the critical root zone of existing trees if trenched or be tunneled a minimum of three feet below existing grade within the tree's critical root zone. If trenching is to be done within the critical root zone, an air spade or hand trenching is required. No root two inches or larger shall be cut. This requirement is for placement of new utilities and does not affect the City's or the utility's ability to access existing utilities for repair, replacement, and maintenance.
(4) Avoidance of Irrigation and/or Drainage Easements:
(a) Any tree planted within any irrigation or drainage easement shall have written approval obtained from the agency holding the easement or managing facilities in the easement.
(b) If any irrigation or drainage easement precludes installation of any trees required by this Section 11-04-09, the width of the required buffer shall be increased to accommodate the required trees or, if the site cannot accommodate the additional buffer, the applicant shall meet all tree mitigation requirements in Section, Tree Preservation.
G. Berms:
(1) Berm slopes shall not exceed three to one (3:1, horizontal: vertical).
(2) Slopes shall not exceed four to one (4:1) on areas that require mowing.
H. Clear Areas:
(1) Trees, shrubs, and other landscaping shall not encroach into the minimum required clear height and width of primary or emergency vehicle access and shall preserve a minimum clear height of 80 inches above all pedestrian pathways.
(2) Trees, shrubs, and other landscaping shall not encroach into any pedestrian walkway, including but not limited to sidewalks and multi-use pathways.
(3) Landscaping shall not block the clear vision triangle at street intersections as determined by the ACHD.
(4) The clear vision triangle shall be kept free of visual barriers including vegetation, except deciduous trees pruned at least eight feet in height above the sidewalk and 14 feet above the roadway, and walls, signs, vehicles, solid fences, or other sight obstructions exceeding three feet in height.
I. Irrigation:
(1) Irrigation Required: All landscape areas requiring irrigation shall be served with an automatic underground irrigation system. Areas of landscaping that will not require supplemental watering after initial establishment are not required to have permanent irrigation.
(2) Irrigation Water Source:
(a) To the maximum extent practicable, all requirements for landscape irrigation for all forms of development and redevelopment shall be met through the use of non-potable surface water as defined by Idaho Code 67-6537.
(b) If non-potable surface water supply is available prior to an annexation of land or City approval of a change of use for the property pursuant to this Code, the use of such water shall be retained for landscaping irrigation purposes following such City approvals.
J. Installation:
(1) Certificate of Completion: Before issuance of the final Certificate of Occupancy, a licensed landscaping professional shall submit to the city certification that the landscaping has been installed in compliance with the approved plans. Certification shall demonstrate that a certified arborist has been consulted.
(2) Installation Schedule: All required landscaping, irrigation systems and site features shall be installed according to the approved landscape plan prior to issuance of a final Certificate of Occupancy.
(3) Extension of Time for Installation: Upon recommendation of the Planning Director, a temporary Certificate of Occupancy may be issued for a specified time period, not to exceed 180 days when:
(a) Due to weather or other circumstances, the landscaping or other required site amenities cannot be completed; and
(b) The applicant has provided surety to the City for the required improvements.
4. Street Frontage Landscaping:
A. Applicability: Street frontage landscaping shall be required to be installed between the curb and inside of sidewalk and between the sidewalk and each street-facing façade or parking lot, as applicable, of a primary Multiple-Family Dwelling, mixed-use, and nonresidential building. Street frontage landscaping between the sidewalk and street-facing facades shall not be required in the MX-1, MX-2, MX-3, MX-4, and MX-5 zoning districts where a landscape buffer would prevent the placement of a proposed building at the allowed front or street side setbacks.
B. Size and Location:
(1) Street frontage landscaping shall be installed along the full width of the required front setback.
(2) All required landscaping shall be located outside any public street right-of-way to the maximum extent practicable.
(3) The required planting area between the sidewalk and façade or parking lot shall be measured from the property line (after dedication of any public right-of-way) or from the back of the sidewalk, whichever is greater.
(4) Landscape buffer widths shall be a minimum of eight feet for Class II and III trees and ten feet for Class I trees, as measured from the inside of the sidewalk to the inside of the curb.
(5) Irrigated landscaping, by agreement with the Ada County Highway District (ACHD), is required in unpaved areas within the undeveloped public street right-of-way.
C. Street Trees: The following standards shall apply to all areas located between a detached sidewalk and a public street right-of-way. If an attached sidewalk is present, the following standards shall apply to the area located between the attached sidewalk and the closest primary building on the property.
(1) All required street frontage landscaping shall be planted with trees and shrubs, or other vegetative groundcover, not including turf that requires regular maintenance, with a minimum density of one tree per 40 lineal feet.
(2) The largest possible class of tree shall be planted in street frontage landscaping to the maximum extent practicable.
(3) Coniferous and evergreen trees are only allowed to be installed in planting areas between sidewalks and streets greater than 20 feet in width in width.
(4) Tree grates shall be a minimum of 36 square feet in size.
(5) Trees located in the public right-of-way shall be comply with Title 7, Chapter 3 of the Boise City Code.
5. Site Perimeter Buffers:
A. Arterial and Collector Street Buffering:
(1) Applicability: Where lots containing Single-Family Detached or Attached, Duplex, Triplex, Fourplex, Co-Housing, Cottage Village Dwellings or Manufactured Home Communities are adjacent to collector or arterial streets as shown on the current Ada County Highway District Master Street Map, the following landscape buffer standards apply.
(2) Frontage Road:
(a) Frontage roads, as permitted by the Ada County Highway District and separated from a collector or arterial street by a 10 foot wide landscape buffer, may be permitted.
(b) The landscape buffer shall be planted with trees and shrubs that at maturity will form a solid screen at least six feet high and a continuous tree canopy.
(3) Side and Rear Perimeters:
(a) If a non-buildable lot abutting an arterial or collector street is created pursuant to Section 11-04-04.4.E(2), Side and Rear Lot Line/Property Lines, it shall be landscaped pursuant to Subsection B below.
(b) If the buffer required by Section 11-04-04.4.E(2), Side and Rear Lot Line/Property Lines, is located within one or more platted lots, only the required side and/or rear setbacks on those lots (not the entire depth of the buffer shall be landscaped pursuant to Subsection B below.
(c) Fences and walls shall not be placed within the following areas:
i. The internal boundary of the required landscape buffer;
ii. A minimum of five feet from the back of attached sidewalks;
iii. At the back of sidewalks separated from the curb by landscaping (unless the fence is not higher than four feet tall); or
iv. 15 feet from back of curb.
B. Other Side and Rear Perimeter Buffers:
(1) Applicability: Side and rear landscape buffers shall be required for all boundaries of Multiple-Family Dwelling, mixed-use, and nonresidential developments that are not adjacent to collector or arterial streets as shown on the current Ada County Highway District Master Street Map.
(2) Size and Location: Landscape buffer widths shall be based on the required setbacks of the underlying zoning district or the minimum width to accommodate the required plantings at full maturity, whichever is greater. All required side and rear buffers shall be located within the property and shall be maintained by the property owner. Where a utility easement is present, buffers shall be located adjacent to but not interfere with the easement.
(3) Parking Lot/Vehicular Use Area Buffers:
(a) If an interior side or rear lot line/property line is adjacent to a parking lot or other vehicular use area including but not limited to vehicle sales areas, truck and bus parking areas and driveways the perimeter landscape strip shall be planted with one tree per 40 lineal feet.
(b) Species shall be selected from the Treasure Valley Tree Selection Guide or an alternative approved by Community Forestry.
(c) Clustering of trees is allowed, but clustered trees shall be spaced no closer than 80 percent of the average mature width of the trees, except as otherwise allowed by Community Forestry.
(d) In the event of a conflict between the standards in Subsection (a) above and the standards in Section 11-04-09.5.B(4), Lot Buffers Between Different Land Uses below, the standard requiring the more intense visual screen, as determined by the Planning Director, shall apply.
C. Lot Buffers Between Different Land Uses:
(1) Applicability: Lot buffers shall be required along the entire contiguous property lines between Residential uses and mixed-use or nonresidential uses.
(2) Required Landscaping: Required buffering shall be of one of the following four different types of landscaping, each of which has a defined purpose, but all of which shall be required to provide visual buffering to a height of eight feet above grade at maturity.
(a) Type A - Screened Separation: Type A landscaping is intended to function as a full screen and visual barrier.
(b) Type B - Filtered Screen: Type B landscaping is intended to function as a visual separator.
(c) Type C - Visual Enhancement: Type C landscaping is intended to function as a partial visual separator that softens the appearance of parking areas and building elevations.
(d) Type D - Other: Type D landscaping is all other landscaped areas that do not quality as Type A, B, or C landscaping.
(3) Standard Buffer Types:
(a) Each required standard buffer shall comply with the buffer widths and planting requirements in Table 11-04.17 below.
STANDARD | TYPE A | TYPE B | TYPE C | TYPE D |
PRIMARY PLANT MATERIALS [1] | A mix of primarily evergreen trees and shrubs | A mix of evergreen and deciduous trees and shrubs | Primarily deciduous trees | Native and low maintenance trees and shrubs, flower and perennial beds, and limited lawn areas |
PLANT SPACING | The selected plant materials and configuration shall provide full horizontal screening of the site feature or adjacent property within six years of installation. | Trees provided at the rate of one tree per 40 linear feet of landscape strip | Trees provided at the rate of one tree per 40 linear feet of landscape strip | N/A |
ADDITIONA L PLANTING MATERIALS | Groundcover | Groundcover | Shrubs and groundcover | N/A |
ALTERNATI VE LANDSCAPI NG | N/A | Alternative tree spacing will be considered provided the plant materials and configuration meet the intent of the standards within three years of planting. | Alternative tree spacing will be considered provided the plant materials and configuration meet the intent of the standards within three years of planting. | N/A |
Notes: [1] All buffer areas shall be comprised of, but not limited to, a mix of evergreen and deciduous trees, shrubs, lawn, or other vegetative groundcover. Fences, walls, and berms may also be incorporated into the buffer area. | ||||
(b) Standard buffer types A, B, C, and D shall be required in the adjacent use situations shown in Table 11-04.18 below.
i. Standard buffer types A, B, C, and D shall be required in the adjacent use situations shown in Table 11-04.18
below.
ADJACENT USES AND ZONING | |||||||
PROPOSED NEW DEVELOPMENT | SINGLE-FAMILY DETACHED | EXISTING RESIDENTIAL IN NONRESIDENTIAL ZONING DISTRICT | NONRESIDENTIAL USE OR VACANT LOT IN NONRESIDENTIAL ZONING DISTRICT | STREET RIGHT-OF-WAY [2] | PUBLIC TRAIL OR OPEN SPACE | ||
WITH FENCE [1] | WITHOUT FENCE [1] | WITH FENCE [1] | WITHOUT FENCE [1] | ||||
ADJACENT USES AND ZONING | |||||||
PROPOSED NEW DEVELOPMENT | SINGLE-FAMILY DETACHED | EXISTING RESIDENTIAL IN NONRESIDENTIAL ZONING DISTRICT | NONRESIDENTIAL USE OR VACANT LOT IN NONRESIDENTIAL ZONING DISTRICT | STREET RIGHT-OF-WAY [2] | PUBLIC TRAIL OR OPEN SPACE | ||
WITH FENCE [1] | WITHOUT FENCE [1] | WITH FENCE [1] | WITHOUT FENCE [1] | ||||
SINGLE-FAMILY ATTACHED & MULTIPLE-FAMILY (UP TO 3 STORIES) | B or C | A | B or C | A | A, B, C, or D | A, B, C, or D (storefront building frontages are exempt) | A, B, C, or D |
OFFICE, COMMERCIAL, AND MIXED-USE (UP TO 3 STORIES) | B or C | A | B or C | A | A, B, C, or D (storefront building frontages are exempt) | ||
OFFICE, COMMERCIAL, AND MIXED-USE (> 3 STORIES) | B or C | A | B or C | A | |||
INDUSTRIAL | B or C | A | B or C | A | A, B, C, or D | ||
PARKING AREA | A or B | N/A | B or C | A | C | C | A, B, C, or D |
SERVICE, LOADING, OR WASTE MANAGEMENT AREA | A
| N/A
| A or B
| A or B except where designed as a shared service areas with adjacent property
| A
| A or B
| |
Notes: [1] Fence refers to a privacy fence placed at or near the property line and behind the landscaping. Fences shall have a maximum height of six feet in residential areas and eight feet in commercial/industrial areas. [2] Buffer width shall follow the minimum setback of the underlying zoning district or the minimum width to accommodate the required plantings at full maturity, whichever is greater. | |||||||
(4) Additional Standards:
(a) Where existing or proposed adjacent land uses cannot be adequately buffered with plant material(s), the City may require inclusion of a wall, fence, or other type of screen that mitigates noise and/or unsightly uses. If a wall or fence at least six feet tall is provided, the planting requirement may be reduced to at least one tree per 40 lineal feet, plus shrubs, lawn, or other vegetative groundcover, in lieu of the requirements of Subsections (2) and (3). Clustering of trees is allowed, but trees shall be spaced no closer than 80 percent of the average mature width of the trees, except as otherwise allowed by Community Forestry.
(b)
Chain-link fencing does not qualify as a screening material. If a chain link fence shall be installed for security or other reasons, the buffer shall still be landscaped as described in Subsections (2), (3), and (4).
(c) Landscaping and screens shall not eliminate required pedestrian access between Residential zoning districts and other districts or land uses.
(d) Landscaping and screens shall not conflict with utility easements.
6. Parking Lot Interior Landscaping:
A. Applicability: Interior parking lot landscaping shall be required in any parking lot with 10 spaces or more, including vehicle sales lots, as listed in Table 11-03.1
: Table of Allowed Uses.
B. Planter Design and Size:
(1) Landscaping shall be installed in planter islands or stormwater infiltration swales designed to allow infiltration and passive treatment of stormwater, as shown in Figure 4.29
.
(2) Planter islands or swales shall be a minimum of eight feet in width for Class II or III trees and 10 feet for Class I trees and shall be at least equal in length to the adjacent parking spaces. Dimensions are measured inside curbs.
C. Landscaping Locations:
(1) No linear grouping of parking spaces shall exceed 10 in a row, without an interior planter island or swale.
(2) Interior planter islands or swales shall be used to guide major traffic movement within the parking area.
(3) Terminal planter islands or swales shall be provided at the ends of rows of parking to protect parked vehicles and confine moving traffic to aisles and driveways.
(4) Interior planter islands or swales shall be distributed as evenly as practicable to reduce the visual impact of long rows of parked cars.
(5) Internal parking lot walkways shall include shade trees planted along at least one side of the walkway and spaced at a minimum of one tree per 30 linear feet.
D. Trees Required:
(1)
Each interior or terminal planter island or swale that serves a single row of parking spaces shall be landscaped in compliance with Type C landscaping as described in Section 11-04-09.5.C(2)(c) and at least one Class III tree.
(2) Each interior or terminal planter island or swale that serves a double row of parking spaces shall have at least two Class II trees and shall be covered with low shrubs or other vegetative groundcover.
(3) Class I trees shall only be allowed where a larger class of tree would create conflicts with overhead utility lines.
(4) Deciduous shade trees shall be pruned to a minimum height of eight feet above the adjacent parking areas. Evergreen trees are prohibited in interior planters.
E. Lights Prohibited: Light poles and fixtures shall be located outside of landscape planter islands, landscape buffers or swales that contain required trees.
7. Building Foundation Planting: All street-facing building elevations, except for those in the MX-5 zoning district and those located within 20 feet of the front lot line/property line in the MX-1, MX-2, MX-3, and MX-4 zoning districts, shall have landscaping along any exposed foundation except those portions of the buildings that provide access for pedestrians or buildings to the building. Foundation landscaping shall comply with the following standards:
A.
The landscaped area shall be at least three feet wide and shall not impede the passage of pedestrians on the adjacent sidewalk.
B. There shall be at least one three-gallon shrub for every three feet of linear foundation.
C. Ground cover plants shall fully cover the remainder of the landscaped area.
8. Tree Preservation: All development shall comply with the following standards.
A. Credit Towards Required Landscaping: Existing trees that are retained or relocated on site may count toward the required landscaping.
B. Parking Reduction: Healthy desirable trees may be preserved in exchange for a parking reduction as set forth in Section 11-04-08.7.D, Tree Preservation.
C. Mitigation Trees:
(1) Each healthy desirable tree with four inch caliper or greater that is removed shall be replaced with one or more trees with a combined caliper equal to the caliper of the tree that was removed.
(2) Each required replacement tree shall be of one-and-one-half inch caliper or greater.
(3) Required replacement trees shall be located either on-site or off-site based on the recommendation of the City Forester.
D. Protection During Construction:
(1) Applicants shall coordinate with Community Forestry during construction to ensure adequate tree protection. Trees within a construction area shall be evaluated by a certified arborist, and a tree inventory of the site should be used to develop a tree protection plan that includes tree descriptions, protection fences, protection of root zones, and other information identified by the City Forester.
(2) Existing trees that are retained shall be protected from damage to bark, branches, and roots during construction. Protection barriers around existing trees are required for the duration of construction. Protection barriers shall be an immovable metal fence with no door or access within the tree protection zone and a minimum height of six feet, and shall be installed prior to construction with adequate signage.
(3) Irrigation shall be provided within the tree protection zone throughout the duration of construction and shall be removed, when appropriate, in conjunction with the installation of permanent irrigation. Acceptable irrigation delivery methods include but are not limited to drip irrigation, above ground sprinklers, soaker hoses, or tanks.
(4) Construction within the tree protection zone of existing trees shall be avoided to the maximum extent practicable, but where construction activities shall occur, they shall comply with the following standards:
(a) Between six and 12 inches of mulch/wood chips or four inches of mulch with ground protection mats on top shall be used to reduce soil compaction.
(b) Trunk protection shall be installed to the maximum extent practicable for trees that are near impervious surfaces, or where vehicles or pedestrians performing work within the tree protection zone may cause damage.
(c) Impervious surfaces may be allowed at a distance from the trunk of a retained tree not less than the diameter at breast height plus five feet.
(d) If excavation is required within the critical root zone, air spading, hand digging, and/or boring methods shall be used, and if root pruning within the critical root zone is required, pruning shall be performed by hand, to the maximum extent practicable.
(e) Grade changes within the critical root zone of existing trees shall be avoided to the maximum extent practicable and are only permitted following a recommendation by the City Forester or a certified Arborist.
(f) Tree pruning for clearance shall be performed by a certified Arborist prior to construction.
(g) New underground utilities to be placed within the critical root zone of existing trees shall be installed as pursuant to Section 11-04-09.3.F(3)(c), Trenching.
9. Stormwater Integration:
A. Purpose: The purpose of this Section 11-04-09
.9 is to encourage the incorporation of vegetated, well-designed stormwater filtration swales into landscape areas where topography and hydrologic features allow. Such integrated site designs improve water quality and provide a natural, effective form of flood and water pollution control. Landscape areas that incorporate stormwater swales shall generally be in addition to the landscaping required by this Section.
B. Design Standards: New Multiple-Family Dwelling, mixed-use, and nonresidential development shall comply with the following standards to the maximum extent practicable, after initial consultation with Planning and Development Services and Public Works Departments regarding the appropriateness of the site and initial designs. Additional information regarding stormwater system design is provided in the Boise Stormwater Design Manual and Stormwater Plant Materials Resource Guide, that are available from the Public Works Department.
(1) Street Swales: Except for Industrial Uses, as listed in Table 11-03.1
: Table of Allowed Uses, swales shall not be located in required landscape buffers along streets. Swales located along streets within required landscape buffers may be approved through the Alternative Compliance process in Section 11-04-09
.11. Swales located within street buffers shall meet the following standards:
(a) Swales shall not exceed twelve inches in storage depth;
(b) The beginning of the swale slope hall be separated from the edge of the sidewalk by a minimum of two feet;
(c) Street trees shall be provided as required by this Section;
(d) Rapid sand infiltration windows shall be integrated for timely drainage of stormwater; and
(e) No infiltration basins are allowed.
(2) Perimeter Buffers: Swales located within required buffers in side and rear yards shall meet the following standards:
(a) Swales shall not exceed 18 inches in storage depth;
(b) Trees shall be provided as required by this Section; and
(c) Rapid sand infiltration windows shall be integrated for timely drainage of stormwater.
(3) Materials and Design:
(a) Gravel, rock, or cobble on the surface of swales shall not exceed 20 percent of the surface area of the bottom of the swale. Cobble may be incorporated into required landscape areas if designed as a dry creek bed or other design feature.
(b) Stormwater swales shall be vegetated with appropriate plant materials. Plant materials shall be a species that are able to withstand the anticipated changes in soil wetness and moisture levels. Examples of appropriate plants materials include, but are not limited to:
i. Trees: River Birch (Betula nigra), American Hornbeam (Carpinus caroliniana), Sweetgum (Liquidambar styraciflua), Cottonwood (populus trichocarpa), Willow (Salix spp), Sycamore (Platanus occidentalis) and Mountain Alder (Alnus tenuifolia).
ii. Shrubs: Red Osier Dogwood (Cornus sericea), Serviceberry (Amelanchier alnifolia), Rhododendrons (Rhododendron sp.), American Cranberry Bush (Viburnum trilobum), Golden Currant (Ribes aureum) and Drummond Willow (Salix drummondiana).
iii. Groundcovers: Sedges (Carex sp.), Spike Rush (Eleocharus acicularis), Maiden Grass (Miscanthus sp.), and Fountain Grass (Pennisetum sp.).
iv. Comprehensive List: A comprehensive and updated list of appropriate plant materials can be found on the City website and should be consulted.
(c) Organic mulch shall not be used adjacent to the flow path. Plant material shall be installed adjacent to the flow path and infiltration area to aid in capturing sediment and reducing clogging.
(d) Open water ponds and holding areas with a permanent water level are not permitted in required landscape or buffer areas, except along Interstate-84. However, ponds that are aesthetically designed with special grading and vegetative features may be approved as provided for through Alternative Compliance.
(e) Slopes shall not exceed three to one (3:1, horizontal: vertical).
10. Fences, Walls, and Screening:
A. Permitted Fencing and Screening Materials:
(1) In Historic Districts, a Certificate of Appropriateness is required for fences made with any material other than wood or wrought iron.
(2) Electric fences are prohibited.
(3) Barbed wire is permitted only in the I-1 and I-2 zoning districts unless the Planning Director determines that it is necessary for public safety and security related to a specific use, and only as the top section of a security fence. Barbed wire shall be located at least 72 inches above grade.
(4) Walls, lattices, and screens shall be considered to be fences.
(5) Boxes, sheet metal scraps, old or decayed wood, broken masonry blocks, or other unsightly materials are prohibited.
(6) Chain-link fencing shall not qualify as a screening material.
B. Permitted Fences:
(1) In Residential and Mixed-Use zoning districts, maximum fence heights are as follows:
(a) Solid fences to a height of 36 inches or open-vision fences to height of 48 inches may be built within the front yard setback. Open-vision may include slatted fences where the gap width is at least 50 percent of the slat width.
(b) Fences to a height of 72 inches may be built within the setbacks along the rear and side property lines. The Planning Director may authorize a greater height if the Planning Director determines the additional height is necessary for public safety and security related to a specific use.
(c) Fences between the front setback and the front of the building may be built to a height of forty-eight inches, except that the Planning Director may approve a greater height to appropriately screen windows from headlights or other disruptive lighting impacts from the street.
(d) One ornamental gate or entryway in a front or street side setback may be allowed to exceed the fence height limits, provided the gate or entryway does not exceed eight feet in height by six feet in width, and is not located within a clear vision triangle.
(2) Standards Applicable to All Fences:
(a) The property owner installing the fence shall locate the fence entirely on their property or within an easement unless agreements are made with the abutting property owners.
(b) If a fence is to be erected upon and within public right-of-way, approval shall also be obtained from the ACHD.
(c) In Mixed-Use zoning districts, concrete and masonry walls of any height and fences over seven feet tall shall be approved by the Building Department.
(d) Fences, walls, or plantings on or within the clear vision triangle shall be limited to 36 inches in height.
(e) Multiple fences, railings, and/ or privacy screens within setbacks shall be separated by a minimum distance of five feet in order to be considered separate
(f) All fences shall be maintained in accordance with Section 11-04-013.1, Landscaping, Buffering, and Screening Maintenance.
C. Retaining Walls: The following shall apply to retaining walls located within setbacks:
(1) Individual retaining walls shall not exceed 36 inches in height when located within a front setback or clear vision triangle.
(2) Individual retaining walls shall not exceed 72 inches in height when located within any other setback.
(3) Walls shall be separated by a minimum distance of five feet in order to be considered as separate walls.
(4) If the wall is located in the HS-O district, multiple walls with a combined height that exceeds the height allowed in the setback may be approved through the Category 2 Hillside Development Permit process if the design complies with the following conditions:
(a) The additional height is necessary and appropriate because of the size, configuration, topography, or other unique characteristics of the property;
(b) The Planning Director and City Engineer have jointly determined that the height, location, and grading for the walls are the minimum necessary for reasonable development of the property;
(c) The additional height will not have any substantial detrimental effect on adjacent or nearby properties;
(d) Terraces between the walls are of sufficient width and depth to accommodate landscaping or other techniques designed to reduce the visual impact. Conditions requiring such techniques shall be incorporated into the permit; and
(e) Clear vision triangles are free of obstructions that exceed 36 inches in height.
D. Screening:
(1) Applicability: This Section 11-04-09
.10.D shall apply to all Multiple-Family Dwelling, mixed-use, and nonresidential development in all districts, except the I-2 zoning district when not adjacent to residential uses.
(2) Parking and Storage Areas: All parking and storage areas including vehicle sales areas, truck parking areas, bus parking areas, and service drives shall comply with the following standards:
(a) A solid Type B screen at least five feet deep, with a height not less than eight feet shall be provided when a parking lot is adjacent to the side and/or rear yard of a residential land use.
(3) Service Areas:
(a) All developments shall comply with all applicable regulations, ordinances, and design standards for solid waste adopted by the City, including specifics around site design and solid waste service. If there is a conflict between the requirements of this Section and solid waste design standards, the Planning Director in consultation with the Director of Public Works shall determine which standard shall apply.
(b) Service areas visible from the street, pathway, public space, or parking area shall be enclosed and screened around their perimeter by a durable wall or fence at least six feet high.
(c) Developments shall use materials and detailing consistent with primary structures on-site. Acceptable materials include brick, concrete block, or stone.
(d) The sides and rear of the enclosure shall be screened with Type A, B, or C as described in Section 11-04-09
.
5.C(2), at least five feet deep in locations visible from the street, dwelling units, customer parking areas, or pathways to soften the views of the screening element and add visual interest.
(e) Collection points shall be located and configured so that the enclosure gate swing does not obstruct pedestrian or vehicle traffic or does not require that a hauling truck project into any public right-of -way.
(4) Mechanical and Utility Equipment:
(a) Roof-Mounted:
i. Roof-mounted mechanical equipment shall be integrated into the building's overall design so as not to be visible from five feet above ground on any lot line/property line, and from any adjacent public rights-of-way or open spaces to the maximum extent practicable.
ii. Where integration to avoid visibility is not practicable, roof-mounted mechanical equipment shall be screened from view from five feet above ground on any lot line/property line, and from any adjacent public rights-of-way or open spaces using parapet walls or an enclosure using one of the primary building façade colors to surround the equipment.
(b) Ground-Mounted: Ground-mounted mechanical equipment located within view of customer entrances and public rights-of-way or open spaces shall be integrated into the overall site design, the architectural design of the building, and screened from public view using one or a combination of the following:
i. A decorative wall, fence or enclosure that is constructed of one of the primary materials and colors used on the adjacent façade of the building, and of a height that is not less than the height of the equipment to be screened; or
ii. Landscaping that is of sufficient height at maturity and of opacity to effectively soften and screen views of the equipment, and that is integrated into the overall landscape plan.
11. Alternative Compliance:
B. Process:
(1) General: The applicant shall request Alternative Compliance in conjunction with the submittal of a Zoning Certificate, Conditional Use Permit, or Design Review application, or upon the determination that the development does not comply with the specific provisions of this Section 11-04-09, at the applicant's option. The request will be considered by the same approval body as the base application. The request shall specify:
(a) The specific requirements that are proposed to be modified;
(b) The reasons for the modification; and
(c) A demonstration of how the alternative means for compliance meets the requirements' intended purpose.
(2) Stormwater Swales: Stormwater swales within front setbacks can be approved administratively provided that the landscape plans approved by the applicable approval body are not changed substantially and comply with Section 11-04-09.9. A landscape plan with swale construction details that incorporates the landscape design shall be submitted for the staff level review.
C. Standard: The proposed alternative means for compliance with the specific requirements shall demonstrate that the alternative provides an equal or superior means of meeting the intent and purpose of the regulation.
D. Required Findings: An application for Alternative Compliance may be approved if the Planning Director determines that:
(1) Strict adherence or application of the requirements is not practicable because one of the following conditions exist:
(a) Topography, soil, vegetation, or other site conditions are such that full compliance is impossible or impractical;
(b) The site involves space limitations or an unusually shaped lot;
(c) Safety considerations;
(d) Other regulatory agencies or departments having jurisdiction are requiring design standards that conflict with the requirements of this Section;
(e) The proposed design includes innovative design features based on "new urbanism," "neotraditional design," or other site designs that promote walkable and mixed use neighborhoods; or
(f) Environmental quality benefits.
(2) The Alternative Compliance provides an equal or superior means for meeting the requirements; and
(3) The alternative means will not be detrimental to the public welfare or adversely affect the uses and character of surrounding properties.
12. Compliance with Design Standards:
A. In addition to the standards required by this Section 11-04-09
, all Multiple-Family Dwelling, mixed-use, and nonresidential development shall comply with the standards and other mandatory content in the Citywide or Downtown Design Standards and Guidelines, as applicable in the area where the property is located.
B. In the event of a conflict between the standards in this Section 11-04-09
and applicable standards in the Citywide or Downtown Design Standards and Guidelines, the provision requiring the higher level of visual building quality and interest, as determined by the Planning Director, shall apply.
(Ord. 27-23, 7-18-2023, eff. 12-1-2023; amd. Ord. 43-23, 12-5-2023)