Page 218 - Des Moines - Zoning, Planning and Design Ch 134, 135

135-5. lANDScAPe AND StreetScAPe DRAFT

Site Trees

is available from the department of public works system of modular units, assembled to form a grid
forestry division. Exceptions to this list may be that supports pavement and traffic loads above while
approved by the city forester. maintaining non-compacted soil beneath for tree
B. Mix of Species. Planted trees shall be a diverse root growth.
combination of permitted species, where possible. B. Intent. Modular pavement support system is
intended to provide additional root growth area for
5.4.3 tree SPAciNG urban trees located within sidewalks or paved areas.
Trees shall be spaced per Table 5.4.4. The goal of the system is increase the life and health
of th trees.
5.4.4 tree MAiNteNANce
Tree trimming, fertilization, and other similar work shall c. Requirement. Trees do not meet the soil volumes
be performed by or under the management of an ISA and permeable area per tree in Table 5.4.5 for are
certified arborist. required to utilize the modular pavement support
system.
5.4.5 PerMeABle SUrFAce D. Submittals. Samples and specifications shall be
For each tree preserved or planted, a minimum amount submitted and the modular pavement support
of permeable surface area is required, unless otherwise system shall be approved by the city arborist prior to
stated in this ordinance. Refer to Table 5.4.5.for soil installation.
volumes and permeable area per tree.
e. Exception. The city forester may approve an
5.4.6 MODUlAr PAVeMeNt SUPPOrt SYSteM alternate system of support for trees that do not

A. Definition. Modular pavement support systems is a meet the requirements in Table 5.4.5 through the
type 1 design exception process.

Table 5.4.5. SOil VOlUMeS & PerMeABle AreA
Minimum
Soil
Typical Soil
Table 5.4.4. MiNiMUM tree Tree Size Permeable Surface Area Volume Measurements
Requirement
SPAciNG (minimum) (minimum) with 3-foot Soil
Depth
Tree Size Minimum Spacing 50 square feet
Street/ (e.g. 5’ x 10’);
Street Tree 30 feet Shade/ trees shall be no closer 1000 12 feet wide x
Overstory than 2 feet to any cubic feet 28 feet long
Shade/Overstory Tree 30 feet Tree concrete edge/surface
Ornamental/understory 15 feet 50 square feet
Tree (e.g. 5’ x 10’); 400 12 feet wide x
Small trees shall be no closer
Evergreen/Coniferous Tree 10 feet than 2 feet to any cubic feet 11 feet long
concrete edge/surface

135-5-6 DRAFT AuGuST 3, 2017