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Description and Purpose. All cut or filled slopes except slopes not exceeding five feet in vertical height or such graded slopes designated as "Native Slopes" (Section 17.06.132.050) shall be planted with permanent ground cover, adequately interspersed with shrubs and trees to protect the slopes against erosion and shall be irrigated with a permanent sprinkler system to promote and sustain growth of said plantings. (Ord. 3411 § 2 (part); April 1, 1975.)
.010 Landscaped slopes shall be categorized for protection and beautification depending on their location and utilization and as described in Sections 17.06.132.010, .020, .030, .040 and .050. The category designated by the landscape architect, subject to review and approval by the City Engineer, will be indicated on each sheet of submitted landscape and irrigation plans indicating both the boundaries and the total area for each category.
.020 Planting materials shall be selected in the recommended list for all cut and fill slopes in the hillside areas. Substitutions for listed recommended planting varieties may be made provided that both the material physical area and size are specified and that such data be supported by recognized horticultural documentation. Substitutions shall be subject to review and approval by the City Engineer, in consultation with the City Arborist, and shall be non-invasive and fire-resistant species with low-water demand. Removal of existing Eucalyptus Trees and/or any other trees that were previously categorized as Specimen Trees and/or Recommended Trees on slopes greater than 15-feet, will require review and approval of the City Engineer for slope stability purposes.
.030 Recommended slope trees are outlined in Table I. Recommended slope shrubs are outlined in Table II. Recommended ground covers are outlined in Table III. Recommended procedures for designing slopes are outlined in Table IV.
(Ord. 3411 § 2 (part); April 1, 1975: Ord. 6447 § 1; November 20, 2018.)
.010 Show Slopes. Those which would include slopes adjacent to or abutting arterial highways with elevations equal to or greater than said highways, entryways into developments, lot front setback areas, side portions of lot areas with slopes less than fifteen feet in vertical height or model complexes, etc., which need immediate and profuse beautification and protection.
.0101 Trees. Show slopes shall be provided with a minimum of forty percent tree coverage, except that all trees planted on slopes less than fifteen feet in vertical height are to be planted no greater than forty feet on center and are to be five gallon size minimum or at least six feet in height at the time of certification. All other slope trees shall be planted using one hundred percent one gallon size varieties or larger and thirty percent five gallon varieties or larger. Trees required adjacent to arterial highways (Section 17.08.354) may be included in the coverage requirement provided they meet all the provisions of the above section.
.0102 Shrubs. Show slopes shall be provided with a minimum of fifty percent shrub coverage. Such slopes must be planted with one gallon minimum size shrubs and must be a minimum of twelve inches in height or a minimum of twelve inches in spread at the time of planting.
.0103 Ground Cover. Slopes may be hand planted with spacing twelve inches on center to insure one hundred percent coverage in one year from the time of planting or may be planted by hydro-seeding utilizing approved mixtures which will insure one hundred percent coverage within one year.
.020 Living Area Slopes. Those which would include slopes adjacent to or abutting arterial highways with elevations lower than said highways, between groups of continuous lots such as those of a planned unit development, side portions of lot areas with slopes greater than fifteen feet or rear portions of lot areas not adjacent to a street.
.0201 Trees. Living area slopes shall be provided with a minimum of thirty percent tree coverage. Such slopes shall be planted with one hundred percent one gallon size or larger trees and thirty percent five gallon size or larger trees.
.0202 Shrubs. Living area slopes shall be provided with a minimum of fifty percent shrub coverage. Such slopes shall be planted with one gallon minimum size shrubs.
.0203 Ground Cover. Slopes may be hand planted with spacing twelve inches on-center to insure one hundred percent coverage in one year from the time of planting or may be planted by hydro-seeding utilizing approved mixtures which will insure one hundred percent coverage within one year.
.030 Community Slopes. Those which would include slopes adjacent to schools, parks, commercial sites, etc., side yard and rear portions of lot areas adjacent to local streets or slopes which may be viewed from arterial highways.
.0301 Trees. Community slopes shall be provided with a minimum of forty percent tree coverage. Such slopes shall be planted with one hundred percent one gallon size or larger trees and thirty percent five gallon size or larger trees.
.0302 Shrubs. Community slopes shall be provided with a minimum of thirty percent shrub coverage. Such slopes shall be planted with one gallon minimum size shrubs.
.0303 Ground Cover. Slopes may be hand planted with spacing twelve inches on-center to insure one hundred percent coverage in one year from the time of planting or may be planted by hydro-seeding utilizing approved mixtures which will insure one hundred percent coverage within one year.
.040 Transitional Slopes. Those which would include slopes immediately adjacent to permanent natural (native) areas, casements, extremely difficult natural terrain, undevelopable land, etc., or railroad rights-of-way and freeways.
.0401 Trees. Transitional slopes shall be provided with a minimum of twenty percent tree coverage except that trees planted on slopes less than fifteen feet in vertical height are to be planted no greater than forty feet on center. Such slopes shall be planted with one hundred percent one gallon size or larger trees and thirty percent minimum five gallon size trees.
Trees required adjacent to freeways, expressways and railroad rights-of-way (Section 17.08.354) may be included in the coverage requirement, provided the material used complies to show slope recommended varieties, would meet all the provisions of the above section and are planted on the slope abutting the top of said slope.
.0402 Shrubs. Transitional slopes shall be provided with a minimum of fifty percent shrub coverage. Such slopes must be planted with one gallon minimum size shrubs. Up to forty percent tree coverage may be substituted for shrub coverage where desired.
.0403 Ground Cover. Slopes may be hand planted with spacing twelve inches on-center to insure one hundred percent coverage in one year from the time of planting or may be planted by hydro-seeding utilizing approved mixtures which will insure one hundred percent coverage within one year.
.050 Native Slopes. Those would include slopes immediately adjacent to public recreational areas such as golf courses, permanent native preserves and lakes, etc. This slope designation requires the prior approval of the Development Services Department.
.0501 Native slopes shall be planted with native and indigenous plant materials, sprinkled with a temporary irrigation system and maintained by the developer until such time as the plantings are permanently established. Said slopes may be planted in their entirety by means of hydro-seeding. (Ord. 3411 § 2 (part); April 1, 1975.)
Planting specifications for trees, shrubs and ground covers are to be included in the landscape plans. Minimum requirements would include:
.010 Pit Excavation and Fill. All plants shall have pits excavated at least one and one-half times the diameter and depth of the container or root ball. Backfill shall contain excavated native solid and a prepared mix with specified additives and amendments as specified in the soils laboratory report.
.020 Staking. Each tree shall be securely fastened to a stake using one inch minimum hose ties or secured by a three wire tie-down system. Staked trees shall be securely supported using three inch redwood or pine poles, or equivalent, with a minimum height of six feet above grade.
.030 Material Removal. All stones or rocks over two inches in size, construction refuse and other deleterious material shall be removed from the slopes to be planted. After completion of the planting, all rubbish and surplus material shall be removed. (Ord. 3411 § 2 (part); April 1, 1975.)
The soil condition and quality on all graded slopes must provide an optimum growing environment for plant materials in order to promote rapid and healthy plant growth for an extended period.
.010 Soil Tests. Fertility soil samples of all slopes shall be taken and a report prepared by a recognized professional soils laboratory.
.020 Soil Additives and Amendments. Soil conditioners such as nitrohumus, nitrolized redwood, fir or pine shaving, etc., nitrous additives such as nitrogen, phosphorous, potash, soil sulfurs, etc. and other soil elements shall be added in the amounts prescribed by the soils laboratory.
.030 Weed Control. Pre-emergent herbicides shall be employed on all slopes except those which are hydro-seeded and post-emergent contact herbicides shall be employed on all planted slopes to destroy the majority of prevalent annual grasses and broadleaf weeds. Application methods and rates shall be outlined by the responsible landscape architect, and should include prewatering slopes daily to allow maximum weed seed germination prior to post-emergent control.
.040 Nurse Crop. A temporary ground cover may be seeded to provide immediate or temporary slope protection on slopes. The nurse crop must be a noncompeting variety or mix that will allow permanent ground cover and shrubs to prevail. Such temporary ground cover may be hydro-seeded.
.050 Irrigation Application. Maximum irrigation application rates shall be specified for each graded slope. Application periods, as a function of precipitation rates, shall be specified in the soils laboratory report. Periods between such applications shall be specified by the responsible landscape architect. (Ord. 3411 § 2 (part); April 1, 1975.)
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