Citygreen Strata Cell Specification

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Citygreen Strata Cell Specification

1

4/5/2011



Citygreen Strata Cell Specification

The purpose of this specification is to inform landscape architects and installers of the detailed
requirements for using the Citygreen
Strata Cell
system

effectively.

Strata Cell

is
a highly engineered solution
that enables street trees to flourish
and prevents heaving
of adjacent pavements and roads.

While the Strata Cell modules have very high strength capacity, the longevity of the pavement
stru
cture is contingent on all components being
correctly installed
in line with

relevant design
criteria.

The following Specification addresses each key step in the planning and installation processes.
Further information may be obtained from
www.citygreen.com

USA/Canada 1866 282 2743,
Australia +612 6578 8250.




Citygreen Strata Cell Specification

2

4/5/2011


Table of Contents

1.0

Definitions

................................
................................
................................
.............

4

2.0

Site Preliminaries

................................
................................
................................
...

5

2.01

P
roduct Storage

................................
................................
................................
..................

5

2.02

Services

................................
................................
................................
...............................

5

2.03

Tree Pit La
yout

................................
................................
................................
....................

5

2.04

Tree Pit Depths

................................
................................
................................
....................

5

2.05

Soil Analysis

................................
................................
................................
.........................

5

3.0

Tree Pit Excavation and Drainage

................................
................................
...........

6

3.01

Excavation

................................
................................
................................
...........................

6

3.02

Reinforcing Collar

................................
................................
................................
................

6

3.03

Drainage

................................
................................
................................
..............................

6

3.04

Sub
-
base
Preparation

................................
................................
................................
..........

6

3.05

Installation of Aggregate Sub
-
base below Strata Cell Matrix

................................
.............

6

4.0

Matrix Installation and Soil Filling

................................
................................
...........

7

4.01

Strata Cell Assembly

................................
................................
................................
............

7

4.
02

Lateral Pipes

................................
................................
................................
........................

7

4.03

Vertical Pipes

................................
................................
................................
.......................

7

4.04

Root/Moisture Barriers

................................
................................
................................
.......

7

4.05

Loading Matrix with Filler Soil

................................
................................
.............................

8

4.06

Filtergrid Separation/Reinforcement

................................
................................
..................

8

5.0

Compaction and Pavement Layers

................................
................................
..........

9

5.01

Reinforcing Collar

................................
................................
................................
................

9

5.02


Tree Pit Opening

................................
................................
................................
.................

9

5.03

Granular Base Course

................................
................................
................................
..........

9

6.
0

Materials

................................
................................
................................
.............

10

6.01

Strata Cell 60 Series

................................
................................
................................
..........

10

6.02

Strata Cell 45 Series

................................
................................
................................
..........

10

6.03

Strata Cell 30 Series

................................
................................
................................
..........

10

6.04

Filter Grid 3030

................................
................................
................................
.................

11

6.05

ReRoot Linear Root Barrier

................................
................................
...............................

11

6.06

RootStop Linear Root/ Moisture Barrier

................................
................................
...........

12

6.07

Aeration Pipes

................................
................................
................................
...................

13


Citygreen Strata Cell Specification

3

4/5/2011


6.08

Filler Soils

................................
................................
................................
..........................

13

6.09

Granular Base Course

................................
................................
................................
........

14

7.0

Addendum

................................
................................
................................
...........

15





Citygreen Strata Cell Specification

4

4/5/2011


1.0

Definitions

A.

Strata Cell:

Patented,
load
-
bearing
,

engineered plastic module with vertical and lateral
interlocks, for creating void space beneath pavements.


B.

Colo
u
red

Indicator Triangle:

Colo
u
red

insert in top face of Strata Cell module, used to
enable

correct alignment of modules. Indicator

verifies module strength.

C.

Strata Cell Matrix:

Assembled and interconnected volume of Strata Cell modules

D.

Lateral Pipe System:

Perforated pipe system for circulation of air, and distribution of
water and nutrients, connected to surface grating.

E.

Vertical Pi
pe System:

Large diameter plastic pipe system for inspection, circulation of air,
and connection to surface grate.

F.

Rootstop Root/Moisture Barriers:

Linear membranes to prevent root or moisture
penetration.

G.

ReRoot Barrier:

Linear root barriers with vertical

integral

root training ribs.

H.

Filler Soil:

Correctly balanced soil mix to provide optimum growth conditions for tree
root systems within Strata Cell matrix.

I.

Filtergrid

:

High strength geogrid bonded to filter fabric for reinforcement of granular
road base
.

J.

Tree Pit Opening:

The pavement opening
into

which the tree is planted.

K.

Granular Base Course:

Compacted granular material to approved regional standards for
support of pavement to relevant Pavement Load design.

L.

Tree Pit:

Excavated space filled with qualit
y soil media for tree planting.

M.

Reinforcing Collar:

A trench between Strata Cell matrix and surrounding soil, lined with
Filtergrid, filled with granular base course and compacted.

N.

CBR
:

California Bearing Ratio

O.

ASTM
:

American Society for Testing and
Materials (
www.astm.org
)





Citygreen Strata Cell Specification

5

4/5/2011


2
.0

Site Preliminaries

Assessment of site conditions and planning
for

installation.

2.01

Product Storage

Strata Cell modules
must
be transported and stored on Citygreen pallets with pallet wrap intact until
ready
for installation. Pallets
should
be positioned on firm level base, so as not to impede traffic or
work flow.

2.02

Services

Installer must obtain accurate service locations f
rom all providers and discuss potential conflicts with
tree pit location prior to commencement. Any amendments to tree pit numbers, dimensions or
location to be approved by the principal Landscape Architect in writing.

Installer

must observe statutory clea
rance and cover measurements for service pipes and conduits.

2.03

Tree Pit Layout

Tree pit locations and dimensions
, as detailed by the specifying Landscape Architect,

must
be
accurately surveyed and marked using string lines,
survey pegs and marking paint
. The L
andscape
Architect
is required
to inspect and approve the tree pit layout, relative to project details, including
granular collar detail.

2.04

Tree Pit Depths

Installer to confirm excavation depths from finished pavement

elevations, including provis
ion for
drainage and base course layers.

2
.05

Soil Analysis

Site soil analysis to be conducted by
a
Soil Analyst
and submitted to Landscape Architect to ensure
adequate drainage of surplus water from base of tree pit.

Where drainage is inadequate, provision
must
be made using land drains connected to main storm
-
water pipe, or grade to soakage pits.
Design of soakage pits to be approved by Landscape Architect, prior to commencement of works.




Citygreen Strata Cell Specification

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4/5/2011


3
.0

Tree Pit Excavation
and Drainage

Excavating the pit, providing adequate drainage and meeting required load
capacity at floor of tree pit.

3
.01

Excavation

Installer to excavate the t
ree pit accurately to
the
dimensions of
the
detail
ed

plans, allowing 200mm
(8”) additional cle
arance in length and width. Side walls of excavated pit to be clean, straight, and
within 15
°

of vertical.
T
ree pit length, width and diagonals at base of pit
to
be measured
to ensure
that correct dimensions are being obtained (measurements shown on tree p
it detail plus 200mm).
Installer to c
onfirm that correct depth has been provided, measuring from finished pavement level,
including any drainage layers. Base of tree pit should be flat
unless there is a drainage layer to be
provided,
in which case
the subg
rade surface
must
have a grade of 5%.

3
.0
2


Reinforcing Collar

The top perimeter of the tree pit
must
be further excavated to a depth of 300mm (12”) and to a
width of 200mm (10”), or
a width
sufficient to permit a narrow foot compacting plate
(reinforcing
collar)
to be
installed
. Sides and base of this excavation
must
be clean and straight.

3
.03


Drainage

Positive drainage to main storm
-
water service from base of tree pit is mandatory if the design
incorporates water harvesting and
is
strongly
recommended if the site soil is not well drained. The
base of

the

tree pit must be graded at 5% to the perforated collection pipe in trench.
This c
ollection
pipe

is

to be wrapped in filter sock and connected to
the
storm
-
water system. A 100mm (4”) layer of

clean aggregate
is
to be placed in base of tree pit and leveled.

3
.04

Sub
-
base Preparation

Base of tree pit must be free of debris and level.
Installer to c
heck CBR of the subgrade below the
proposed granular pavement layers to ensure it meets the
applica
ble

pavement design criteria. If the
subgrade is fill confirm th
at it is

compacted to a minimum of 95% of maximum dry density at
optimum moisture content in accordance with ASTM D 698 Standard Proctor Method.

C
ompact the subgrade

in natural ground with a minimum of three passes of a suitable vibrating
compacting machine or apply other compaction forces as needed to achieve the required subgrade
compaction rate.

Apply additional compaction forces at optimum water levels.

If an aggr
egate drainage layer is specified cover
top and sides
of
with a proprietary non
-
woven filter
fa
bric to engineer specifications and ensure the sides of the drainage layer are compacted against
the sides of the excavation to the density specified.

3.05

Insta
llation of Aggregate Sub
-
base below Strata Cell Matrix

Install aggregate sub
-
base to the depths indicated in the drawings

and c
ompact to a minimum of
95% of maximum dry density at optimum moisture content
,

in accordance with ASTM D 698
Standard Proctor Met
hod. Compact the subgrade with a minimum of three passes of a suitable
vibrating machine or apply other compaction forces as needed to achieve the required subgrade
compaction rate.


Citygreen Strata Cell Specification

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4/5/2011


4
.0

Matrix Installation and Soil Filling

Assembling the matrix and associ
ated components, filling with soil.

4
.01

Strata Cell Assembly


(
Refer

illustrated guide
s in Addendum
)

Check and confirm all tree pit dimensions and mark location of tree with surveyor pegs before
commencing assembly of Strata Cell matrix. Rectify any discrepancies or errors.

Ensure base of pit is level and free of debris. Place

the

first Strata Cell in le
ft corner of tree pit with
colored

indicator triangle pointing towards the corner.

Place second module next to the first one with
colored

indicator triangle aligned towards
corner

and
snap together, checking that the two connecting edges have matching numb
ers. Continue
connecting modules from left to right until the first row is complete, then start the second row and
complete from left to right, connecting all modules at adjacent edges, ensuring all numbers are
paired correctly and
colored

indicators are a
ligned, until first layer is complete.

The second layer is commenced by placing the first Strata Cell in left corner of tree pit with
colored

triangle pointing to left side of pit


i.e. counter
-
rotated 45
°

from the first layer. Connect th
is

module
to the
first module in layer below and then proceed to complete the second layer. Ensure that all
indicator triangles are aligned and all modules connect together firmly, laterally and vertically.

The third layer is assembled with
colored

indicators aligned as pe
r first layer and a fo
u
rth layer is
assembled as per the second layer, until the specified number of layers is in place.

An opening for the tree root ball (as detailed and dimensioned on the tree pit plans)
must be
provided within the matrix.

4
.02

Lateral

Pipes

As per tree pit design details, p
erforated aeration pipes
should
be installed within the top layer of
modules. The pipe must be laid in a complete connected circuit within 600mm (24”) of

the

outer
edge of
the
matrix. Junctions and risers
should
be f
itted at spacings of no more than 3.6 metres
(12’). Riser pipes to be trimmed to 150mm (6”) above finished pavement level and supported in

a

vertical position by temporary staking. Open ends of pipe to be sealed with caps or weather
-
proof
tape.

4
.03

Verti
cal Pipes

Where vertical aeration or inspection pipes are specified they should be placed within the large
central opening of the Strata Cell modules, in correct locations. Pipes should be trimmed to

a

length
of
150mm (6”) above finished pavement level.
Open ends of pipes to be sealed with caps or
weather
-
proof tape.

4
.04

Root/Moisture Barriers

Where
specified i
n the tree pit plans
,

a linear Rootstop Barrier
should
be installed. Typically this will
be placed between the Strata Cell matrix and the side wa
ll of the pit. Ensure the barrier is inserted to

Citygreen Strata Cell Specification

8

4/5/2011


the full depth of the pit and is not in contact with any sharp debris or stones
t
hat may puncture the
barrier. Any joins
must have a 150mm (6”)
overlap and

be

taped both sides using Rootstop tape over
clean
dry surfaces. The top edge of the Rootstop barrier
should
be trimmed with a sharp knife to
level with the top of the Strata Cell matrix.

4
.05

Loading Matrix with Filler Soil

En
sure that all required filler so
il testing and certification is complete to
the

satisfaction of
the
Landscape Architect prior to loading into

the

tree pit.

When matrix is fully assembled, with all specified piping and barriers in place, the filler soil can be
loaded into the matrix.

Soil should be placed
in the matrix
using an excava
tor bucket and spread
with rakes or shovels until the void spaces are filled. Ensure the outer trench for
the reinforcing
collar is kept clean and free of filler soil.

Matrix
is
to be vibrated using plate vibration or needle
vibration equipment

in order

to

shake soil into all voids.

Continue loading dry soil, raking out and vibrating, until matrix is filled.

Should the filler soil constituents and moisture content not permit the voids
to be
fully filled,
assemble the Strata Cell modules in layers and progr
essively fill
, layer by

layer.

Note:

In some instances an air layer is detailed in the top of the matrix. In this case soil is loaded,
spread and vibrated in smaller amounts, to ensure an even distribution of soil beneath the air layer.

4
.06

Filtergrid

Sepa
ration/Reinforcement

The outer trench for provision of
the
reinforcing
collar
should
be cleaned and all filler soil and debris
removed. Place the Filtergrid layer
on

the
top of matrix and cut to length, ensuring that the material
fully
covers the top
of the matrix, the upper side walls of the matrix, and the bottom of the adjacent
trench for
reinforcing
collar. Any material joins must be straight, free of debris and over
-
lapped
150mm (6”). Pipe penetrations to be prov
ided by means of two intersecting s
lits cut with a sharp
knife to form a cross.




Citygreen Strata Cell Specification

9

4/5/2011


5
.0

Compaction and

Pavement Layers

Enclosing the tree pi
t

and
placing

pavement layers, to comply with design
loads.

5
.01

Reinforcing

Collar

Load the granular base course material into the base of the collar trench ensuring the Filtergrid layer
is not displaced from the base of the trench. Compact the granular material in 150mm (6”) lifts until
the collar is level with the top of the matrix.

5
.
02

Tree Pit Opening

Confirm the exact required position of the tree pit opening from project details and with reference
to survey markers. Cut Filtergrid layer and fold back to expose the tree pit opening. Position form
-
work to provide for poured concrete

system, or other method as specified
i
n project details.

Place
ReRoot linear ribbed root barrier within the tree pit opening with vertical ribs facing inwards.
Ensure bottom edge of ReRoot barrier is placed on the Strata Cell matrix and upper edge is at
f
inished pavement level. Trim to suit with sharp knife. Ensure any joins are overlapped a minimum of
150mm (6”), are clean and dry and taped both sides with Root Stop tape.

5
.03

Granular Base Course

Load and spread granular base course material onto the Fi
ltergrid layer in an even depth of 100mm
(4”). Compact this layer with a vibrating plate compactor with a mass of 1200kg


1400kg/m
²

of base
plate, to specified compaction levels. Continue building compacted granular layers to required levels
including the

reinforcing collar.




Citygreen Strata Cell Specification

10

4/5/2011


6
.0

Materials

6
.01

Strata Cell 60 Series



Engineered plastic module
s

designed to
connect

together to create a matrix
, for use

beneath
pavements. The interconnected skeletal matrix provides in excess of 94% void space for
filling with soil media, or storing/ detaining storm water. Due to the high structural integrity
of the modules, these matri
c
es can be
used

close to trafficked
pavement surfaces
-

subject to
engineers’ certification.



100% recycled Polypropylene (PP) reinforced with fiberglass.



No steel components
-

corros
ion

free.



Ultimate Load Strength 624 kpa (90.5 psi), verified by laboratory crush tests.



50.8 cm (20 inch) x 50
.8cm (20 inch) x 25cm (10 inches) in height



0.0645 m³ (2.2778 ft³) per module



15.3 modules/ m³ 11.853 modules/ yrd³


6
.02

Strata Cell 45 Series




Engineered plastic module
s

designed to
connect

together to create a matrix
, for use

beneath
pavements. The int
erconnected skeletal matrix provides in excess of 94% void space for
filling with soil media, or storing/ detaining storm water. Due to the high structural integrity
of the modules, these matri
c
es can be
used

close to trafficked pavement surfaces
-

subject
to
engineers’ certification.



100% recycled Polypropylene (PP) reinforced with fiberglass.



No steel components
-

corrosi
on

free.



Ultimate Load Strength 450 kpa (65.26 psi), verified by laboratory crush tests.



50.8 cm (20 inch) x 50.8cm (20 inch) x 25cm (10
inches) in height



0.0645 m³ (2.2778 ft³) per module



15.3 modules/ m³ 11.853 modules/ yrd³


6
.03

Strata Cell 30 Series



Engineered plastic module
s

designed to
connect

together to create a matrix
, for use

beneath
pavements. The interconnected skeletal matrix provides in excess of 94% void space for
filling with soil media, or storing/ detaining storm water. Due to the high structural integrity
of the modules, these matri
c
es can be
used

close to trafficked
pavement surfaces
-

subject to
engineers’ certification.



100% recycled Polypropylene (PP)



No steel components
-

corrosi
on

free.



Ultimate Load Strength 306 kpa (44.38 psi), verified by laboratory crush tests.



50.8 cm (20 inch) x 50.8cm (20 inch) x 25cm (10
inches) in height



0.0645 m³ (2.2778 ft³) per module



15.3 modules/ m³ 11.853 modules/ yrd³


Citygreen Strata Cell Specification

11

4/5/2011


6
.04

Filter Grid 3030

Composite of a laid geogrid made of stretched, monolithic polypropylene (PP) flat bars with welded
junctions and a mechanical bonded filter geo
textile welded within the geogrid structure, used for
reinforcement in many fields of civil engineering including road construction, landfill and hydraulic
engineering.

Property

Test Method*

Unit

30/30 Q1

151 GRK 3

Geogrid

30/30 Q1

Raw material

-

-

Polypropylene (PP),
white

Mass per unit area

EN ISO 9864

g/m
²

200

Max. tensile strength, md /
cmd**

EN ISO 10319

kN/m


30/




䕬Eng慴aon⁡ om楮慬a
獴牥ng瑨ⰠmT /⁣mT⨪

䕎⁉协‱0319

%

≤8 / ≤8

呥n獩s攠s瑲敮t瑨⁡琠2┠
敬eng慴aonⰠmT ⁣mT⨪

䕎⁉协
10319

歎/m

12 / 12

呥n獩s攠s瑲敮t瑨⁡琠5┠
敬eng慴aonⰠmT ⁣mT⨪

䕎⁉协‱0319

歎/m

24 / 24

䅰敲瑵牥⁳楺攬T⁸⁣mT**

-

mm⁸ mm

䅰p牯砮″2⁸″2

P牯Tuc瑩tn⁳ 散楦楣e
敬eng慴aon

-

%

O

Geotextile

151 GRK 3

Raw material

-

-

Polypropylene (PP),
white

Mass
per unit area

EN ISO 9864

g/m
²

≥150

M慸⸠a敮獩e攠獴牥ng瑨ⰠmT /
捭T**

䕎⁉协‱0319

歎/m

7⸵./ 11.0

䕬Eng慴aon⁡ m慸a⁴敮獩e攠
獴牥ng瑨ⰠmT /⁣mT⨪

䕎⁉协‱0319

%

40 / 30

Pun捴畲攠co牣e

䕎⁉协‱2236

N

1ⰶ70

D楳i污捥m敮e⁡ 獴慴楣
pun捴畲攠c瑲敮t瑨


䥓传12236





D整散eo爠r敳e敤

-

-

奥Y

副汬⁤ m敮獩on猬⁷楤瑨⁸t
汥lg瑨

-

m⁸

4⸷.⁸ 100

*

based on, ** md = machine direction, cmd = cross machine direction


6
.05

ReRoot
Linear Root Barrier



Linear root deflecting barriers to be used in proximity to
tree root ball to protect all
pavement layers. Vertical, integral ribs guide tree roots down into StrataCell matrix beneath
pavement.



Continuous rolls to minimize joins and possible penetration.



Widths to suit application and pavement depth


Citygreen Strata Cell Specification

12

4/5/2011




100um thickness



100% High density Polyethylene
.
This resin meets FDA regulation 177.1520 for food
packaging.

Nominal physical properties:

PROPERTY*

ASTM D

UNIT

VALUE

Density

1505

g/cm
³

0.952

Melt Index

1238

g/10 min

0.35

ESCR,F



Condition B

1693

h

50

Tensile Yield
Strength

638 @ 50mm/min

MPa

27

Elongation at Break

638 @ 50mm/min

%

>
600

Brittleness Temperature

746

°
C

<
-
90

Flexural Modulus

790

MPa

1310

Shore Hardness D

2240

-

66

*

Physical properties reported herein were determined on compression molded specimens

prepared in
accordance with Procedure C of ASTM D 1928.


6
.06


RootStop
Linear Root/ Moisture Barrier



F
or use within or
to line

the main tree

pit, where moisture or roots must be prevented from
entering an external zone. Commonly used to protect critical
services, or road based
courses.



Continuous rolls to minimize joins and possible penetration.



Widths to suit application and pavement depth



100% High density Polyethylene. This resin meets FDA regulati
on 177.1520 for food
packaging.




Citygreen Strata Cell Specification

13

4/5/2011


Nominal physical
properties:

PROPERTY*

ASTM D

UNIT

VALUE

Density

1505

g/cm
³

0.952

Melt Index

1238

g/10 min

0.35

ESCR,F



Condition B

1693

h

50

Tensile Yield Strength

638 @ 50mm/min

MPa

27

Elongation at Break

638 @ 50mm/min

%

>
600

Brittleness Temperature

746

°
C

<
-
90

Flexural Modulus

790

MPa

1310

Shore Hardness D

2240

-

66

*

Physical properties reported herein were determined on compression molded specimens prepared in
accordance with Procedure C of ASTM D 1928.


6
.07


Aeration Pipes



Flexible, perforated pipe system
for optimizing oxygen exchange within the tree

pit soil. This
lateral pipe system is connected to the surface by means of T
-
pieces and riser pipes and also
forms the means of distribution for harvested storm water, and supplementary irrigation or
nutrient
dosing.



100% High density Polyethylene pipe



Moulded T
-
Pieces and junctions



Cast aluminum ventilation grilles with tamper
-
resistant grating.


6
.08


Filler Soils

Refer addendum:
Filler Soil Specification for Strata Cell Tree Pit.docx




Citygreen Strata Cell Specification

14

4/5/2011


6
.09


Granular Base
Course

Granular material meeting the standard below, or equivalent (approved by specifying Landscape
Architect

in consultation with qualified Civil or Geotechnical Engineer
):



ASTM D1241
-
07, Type 1, Gradation B Standard Specification for Materials for Soil
-
Aggregate
Sub base, Base, and Surface Courses.

a.

Type I mixtures shall consist of stone, gravel, or slag with natural or crushed
sand and fine mineral particles passing a No. 200 sieve.

Sieve

Percent Passing

37.5mm (1.5”)

100

25mm (1”)


-


9.5mm (3/8”)


-


4⸷.mm
No 4)


-


2⸰mm
No‱0)


-


425

m

⡎o‴0)


-




m

⡎o 200)

5
-






Citygreen Strata Cell Specification

15

4/5/2011


7
.0

Addendum



Strata Cell Connection Procedure Layers 1 & 3.pdf



Strata Cell Connection Procedure Layers 2 & 4.pdf



Citygreen Urban LEED


Performance Assessment.pdf



Filler Soil Specification for Strata Cell Tree Pit.docx