Watershell Catalogue Specto Ct August 2009

Introduction
Specto Civil Technology Inc.’s catalogue contains our range of Watershell storm water management
products. You will find detailed product descriptions as well as tender details, example drawings
and reference projects.
Specto Civil Technology Inc. is always available for advice and support during the design stages of
your projects.

Specifications and drawings are subject to change without prior notice as we continue to develop
our products.

© All rights reserved. No part of this publication may be reproduced in any form or by any means, electronic, mechanical,
photocopying, recording or otherwise, without the prior written permission of Specto Civil Technology Inc..

Registered trademark Watershell® is owned by Waterblock BV, Zundert, The Netherlands.
Specto Civil technology Inc. is the official Waterblock BV Distributor in North America.

Specto Civil Technology Inc. | T (604) 287 4327 | F (604) 287 4343 | info@watershell.ca | www.watershell.ca /v2.0

Contents
Catalogue - Watershell 2
- XPE Foam 4

1 Watershell modules 4 – 55 - Work description 5
1.1 Watershell modules installation 5
1.2 Concrete specification 6
1.3 Concrete pouring method 7

2 Watershell Atlantis - Work Description 8
2.1 Watershell Atlantis installation 8
2.3 Concrete pouring method 13

3 Infiltration Field – Summary 15
Infiltration Field – Projects 16
Infiltration Fields – Work Description 26
3.1 Preparation 26
3.2 Geotextile installation 28
3.3 Tile installation 28
3.4 Modules installation 29
3.5 Concrete reinforcement installation 29
3.6 XPE board installation 30
3.7 Installing inlet/ outlet pipes and inspection manholes 31
3.8 Backfill 32
Infiltration Field – Step by Step Work Description 34
Infiltration Field – Tender Description 36
Infiltration Field – Drawing Example 38

4 Infiltration Cellar - Summary 39
Infiltration Cellar – Projects 40
Infiltration Cellar – Tender Description 45
Infiltration Cellar – Drawing Example 48

5 Water Storage Cellar – Summary 49
Water Storage Cellar – Projects 50
Water Storage Cellar – Tender Description 60
Water Storage Cellar – Drawing Example 62

Specto Civil Technology Inc. | T (604) 287 4327 | F (604) 287 4343 | info@watershell.ca | www.watershell.ca

Contents
6 Root Bridge – Summary 63
Root Bridge – Projects 64
Root Bridge – Tender Description 68
Root Bridge - Drawing Example 70

7 Tree Environment Protection – Summary 71
Tree Environment Protection –Projects 72
Tree Environment Protection – Tender Description 79
Tree Environment Protection – Drawing Example 81

8 Light Weight Backfill – Summary 82
Light Weight Backfill – Projects 83
Light Weight Backfill – Tender Description 89

Specto Civil Technology Inc. | T (604) 287 4327 | F (604) 287 4343 | info@watershell.ca | www.watershell.ca

Catalogue - Watershell
Watershell is a plastic dome shaped module with fixed width and variable height. The modules create formwork for
concrete pouring. Due to its unique dome shape and ingenious joints a concrete construction arises with columns spaced
every 50 cm. A large cavity underneath the modules forms after concrete has hardened. The large number of columns
makes for a structure with very high load bearing capacity using a minimum of reinforcement and concrete. The modules
can be used as infiltration fields, infiltration cellars, root bridges, tree root environment protection, lightweight backfill and
raised floors. Watershell module measurements:

Watershell 4 - item # 2004
B L h H weight concrete Nett capacity
cm cm cm cm kg/pc m3/m2 m3/m2
50 x 50 10 3 4 0.770 0.004 0.036
Pallet 110 x 110 cm Applications
max height weight # of area • drainage
m kg pieces m2 • raised floors
1.10 310 400 100

50 x 50 26 4.5 8 1.240 0.012 0.063
max height weight # of area • root bridge
m kg pieces m2 • drainage
2.50 490 400 100 • raised floors

50 x 50 31 8 12 1.250 0.016 0.073
2.50 500 400 100 • raised floors

50 x 50 31 11 16 1.300 0.034 0.105
2.50 400 300 75 • raised floors



50 x 50 33 13 20 1.450 0.035 0.140
max height weight # of area • infiltration
m kg pieces m2 • water detention
2.50 450 300 75 • raised floors

50 x 50 34 21 27 1.650 0.040 0.205
2.50 510 300 75 • raised floors

50 x 50 30 29 35 1.850 0.056 0.269
2.50 570 300 100 • raised floors

50 x 50 32 34 40 2.000 0.060 0.315
2.50 620 300 75 • raised floors

50 x 50 35 39 45 2.100 0.065 0.350
2.50 650 300 75 • raised floors

50 x 50 35 44 55 2.400 0.090 0.395
max height weight # of area • Tree root protection
2.50 730 300 75 • raised floors

Specto Civil Technology Inc. | T (604) 287 4327 | F (604) 287 4343 | info@watershell.ca | www.watershell.ca 2 /v2.0

Watershell Atlantis 16 - item # 2016A
50 x 50 31 11 16 1.500 0.034 0.105
max height weight # of area • infiltration/water detention
m kg pieces m2 • tree root protection
2.50 460 300 75 • raised floors

Watershell Atlantis Column Base Support - item # 20CBS
max height weight # of area The column base is used to support the columns when using
the Watershell Atlantis system. The column base stabilizes the
m kg pieces m2
system and prevents concrete spills. De-aeration slots provide
2.50 460 300 75 an escape for trapped air.

Watershell Atlantis System
height column height pipe cutoff length concrete Nett capacity
cm cm cm m3/m2 m3/m2
75 59 58 0.055 0.673

100 84 83 0.064 0.913

125 109 108 0.073 1.154
150 134 133 0.082 1.394
175 159 158 0.091 1.635
196 (max.) 180 179 0.099 1.837


Catalogue - XPE Board
XPE Board Standard thickness (T): 35 mm (tolerance -0/+5mm)

Standard non woven geotextile: 150 grams Class III
Standard sizes: Board, 1 x 2.25 m
Roll, 1 x 10 m.
Roll, 2 x 65 m.
(tolerance on length and width -0/+3%)

RecyTop - item # 20.RT35

Application
• Drainage and protection
• Horizontal drainage grooves for extra drainage
• Standard 15 grooves

S-Foam - item # 20.SF

Application
• Protection and attenuation
• Flat surfaces
• Higher compaction than RecyTop for better
attenuation

NetFoam - item # 20.NF25

Application
• Protection
• One side has a HDPE mesh for higher strength and
better point load distribution

Layered product:
1. Geotextile
2. Mesh
3. Foam


1 Watershell 4-55 – Work Description
1. Watershell 4-55 - Work description

1.1 Watershell modules installation

Install the modules working from left to right, pointing the arrows on the modules in the same direction
(fig.1). Follow the modules’ indicated installation pattern. The modules’ rims overlap and connect
to create a strong solid form. To avoid height differences between the modules, the modules’ legs
should be joined together consistently and placed on a level floor.

Fig.1: Modules positioning pattern, leFt to right, arrows in one direction


1.2 Concrete specification

After installing the modules the formwork is ready to be filled with concrete. It is very important to
calculate the amount of concrete needed.
Concrete is poured into the formwork’s columns and on top of the modules to create the structure.

Concrete specification for Watershell modules (Watershell Atlantis System excluded):

• Concrete strength C20/25 mpa
• S3 consistency
• Granular stone Ø 4 – 32 mm with max Ø = 32 mm
• Chloride grade CL 0.40 reinforced concrete

The concrete cover layer will vary in thickness, steel reinforcement and concrete quality, dependant
on environment, load-bearing capacity and system geometry. Expansion joints may be needed and
have to be taken into account. Contact your local Watershell supplier for more information and/ or
engineering questions.

The amount of concrete needed to fill the formworks’ columns to the top of the modules depends
on the modules’ height. Table 1 depicts the amount of concrete in cubic metres needed with various
Watershell modules, excluding the amount needed for the concrete cover layer.

Watershell height cm Concrete amount m3

16 0.034
20 0.035
27 0.040
35 0.056
40 0.060
45 0.065
55 0.090

table 1: concrete aMounts in coluMns between Modules

For example:

The total amount of concrete needed with Watershell 45 and a flooring of 100 mm thickness:
0.065 m3/m2 + 0.1 m3/m2 = 0.165 m3/m2


1.3 Concrete pouring method

It is important to start pouring concrete in the middle of the floor in the centre of the module. Do
not pour concrete directly into the columns, but fill them from the centre of the modules at all times.
Work from the centre of the floor outwards concentrically (fig. 3). When using a concrete pump make
sure the flow is slow and consistent, preferably using the hose horizontally. Finish the floor and make
sure to avoid shrinkage of the floor after pouring.

Start pouring here
continuing in direction
of the arrows

Fig. 2: concrete pouring pattern


2 Watershell Atlantis – Work Description
2. Watershell Atlantis Work description

2.1 Watershell Atlantis installation

The Watershell Atlantis system differs from all other Watershell modules. The Watershell Atlantis
system consists of 500 mm x 500 mm dome shaped modules 160 mm in height. The connected
Atlantis modules form a concrete formwork system. Rigid pipes with a 110 mm Ø on a 500 mm x
500 mm grid carry the formwork system. The pipes’ lower ends are capped of with the Watershell
Atlantis column base supports (fig. 3). After concrete pouring the system has a raised concrete cover
supported by concrete columns.

Fig.3: watershell atlantis systeM with Modules, coluMns and coluMn base support.


2 Watershell Atlantis– Work Description
Installation conditions:
a) Construction length (L) and width (B) are multiples of 500 mm + 150 mm, as follows:
Length: L = Nl x 500 mm + 150 mm, Nl = number of modules lengthways
Width: B = Nb x 500 mm + 150 mm, Nb = number of modules sideways
For example (fig.3): L = 7 x 500 + 150 = 3650 mm and B = 5 x 500 + 150 = 2650 mm

b) Maximum inner height of the system is 1960 mm, with 1800 mm pipe columns and 160 mm
column supports. Fig. 4 shows a pipe cutoff length of 1490 mm.

Fig.4: pipe coluMns MeasureMents, MaxiMuM inner height 1960 MM.


Install modules working from left to right, pointing the arrows on the modules in the same direction
(fig.1). Follow the modules’ indicated installation pattern. The rigid plastic columns have a 110 mm
diameter and a 2 mm (max.) wall thickness and need to be cut to length perpendicularly, leaving
smooth and clean edges. The modules’ corner rims lock around the pipe. The column base support
is used to create columns with the Watershell Atlantis system. The column base support stabilizes
and supports the system and prevents concrete spills. De-aeration slots in the column base supports
make for excellent density.

Modules can be cut lengthways and refitted to size (fig.5).

Fig.5: Modules can be cut and reFitted to size


Modules can be cut and refitted to size even alongside an angled wall. To support the refitted
modules, 110 mm Ø holes are cut into the modules alongside to fit in the plastic columns. Secure
the columns in the holes with stainless steel wires (fig.6).

Fig.6: extra coluMns with angled walls


Expanded Polystyrene (EPS) insulation (100 mm (L). x 70-100 mm (W)) is used to fill the gap between
the Watershell Atlantis system and the system wall. Close any gaps with expanding foam (fig.6).
Larger projects can be fitted with cast in place holes to accommodate manholes, lids or covers
to access the Watershell Atlantis systems’ cavity. This way the Watershell Atlantis system is fully
inspectable and cleanable. These manholes usually measure 800 mm x 800 mm and are placed on
a 8 by 8 grid of columns (fig.7).

Fig.7: installation oF a 800x800 MM exclusion ForM in concrete Floor


2.2 Concrete specifications

After installing the modules, the system is ready to be filled with adequately flowing concrete. Concrete is
poured into the formwork’s columns and on top of the modules to create pedestal or raised flooring.

Concrete specification for Watershell Atlantis modules (columns to top rim of modules):

• Concrete strength C28/35
• Consistency: F5, fluid
• Granular stone Ø 4 – 16 mm, max Ø = 16 mm
• Chloride grade: CL 0.40 reinforced concrete

Use S3 or S4 concrete consistency for the top flooring with a max. granular Ø of 32 mm. Steel mesh
reinforcement is to be placed on top of spacers.
The necessary amount of concrete per m3 per m2 needed in a project is calculated with this formula:

s/1000 m3/m2 Floor thickness on top of modules
0.034 m3/m2 Amount in Watershell modules
h/1000 x 0.036 m3/m2 Amount in pipe columns

(s/1000) + (0.034) + (h/1000 x 0.036) m3/m2 Total amount

Concrete on top of the system outer walls has not been taken into account (fig. 4).

2.3 Concrete pouring method

Work from the centre of the floor outwards concentrically (fig.8). Compact concrete to specification,
but avoid using poker vibrators, especially inside the columns. Make sure to avoid shrinkage of the
concrete floor after pouring.



Fig.8: concrete pouring diagraM


3 Infiltration Field - Summary
Flood prevention, runoff water reuse and Infiltration Field Advantages:
storm water management are important
issues in environmentally sustainable urban • Simple and fast installation
developments. Watershell Infiltration systems • Inspectable and cleanable
offer flexible solutions to every storm water • High load bearing capacity
project. Runoff water is temporarily stored to • No backfill needed
reduce and mitigate the total runoff volume • Variable area, L x W x H
and maximize the amount of runoff returned to • High water bearing capacity up to 401 l/m2
shallow groundwater via recharge. It maintains • Relatively low cost
pre-development flow regimes, surface water • Multiple use of space
quality and local temperature ranges as well as • Large infiltrating area
restricts post-development peak runoff flow- • Low volume transport
rates to that of the pre-development stage. • Applicable with high groundwater levels
Infiltration systems are built in under parking • Great expertise and many reference
lots, squares, roads and parks. projects

Fig.9: watershell inFiltration systeM drawing exaMple

Notices, please consider: Watershell load bearing concrete thickness outer height water
type capacity D. floor D. tile mm bearing
• Watershed area kN mm mm capacity
• Runoff water quality m3/m2
• High peak runoff amount Watershell 27 none 80 45 395 0.234
• Groundwater levels (G.W.L.) Watershell 27 450 120 80 470 0.256
• Ground permeability Watershell 27 600 120 80 470 0.256
• Dissipating speed Watershell 35 none 80 45 475 0.298
• Available space Watershell 35 450 120 80 550 0.320
• Traffic load Watershell 35 600 120 0 550 0.320
• Ground cover Watershell 45 none 80 45 575 0.379
• Earth pressure allowance Watershell 45 450 120 80 650 0.401
Watershell 45 600 120 80 650 0.401
Contact your local Watershell system supplier for more information and/ or engineering
questions.


3 Infiltration Field - Projects
Principal: Municipality
Area: 50 m2
Water bearing capacity: 20 m3
Load bearing capacity: 450 kN
Material: Watershell 45

Geotextile, concrete tiles and Watershell modules Length 10 m x width 5 meters

Inlet pipe for storm water Installing spacers and steel mesh concrete reinforcement

To accommodate water by-laws in an urban area the storm water has to be diverted from the sewer
system. Storm water from roof tops and streets is collected and diverted into the Watershell infiltration
system. Storm water dissipates into the sub soil at a controlled rate. The amount of time it takes for
the system to totally infiltrate is dependant on the permeability of the surrounding soil.


Principal: IKEA
Area: 5,000 m2
Water bearing capacity: 1,940m3

Installing the modules System overview

Pouring concrete Load bearing within a week

IKEA built a new facility on 7.4 acres. The storm water amount generated from the impermeable
surfaces and the roof exceeded the amount the streams and canals could handle and by-laws
didn’t allow for this type of water to be dumped into existing open waters. IKEA had to come up
with a solution for the storm water issue. The solution presented to them was to create a 4 m
x 130 m infiltration system underneath the parking lot using the Watershell system. Storm water
collected from the parking lot and the roof is redirected into the infiltration system. Storm water
slowly dissipates into the sub soil. The system is able to accommodate peak rainfall and store up
to 1,940 m3 of water at a time.


Area: 500 m2

Installing the Watershell modules Steel mesh or rebar

Overview of the 500 m2 system Pouring concrete

This Municipality has chosen to divert storm water from the sewer systems. As the permeability of
the soil is very good they wanted a large infiltration system that could contain the water so it can
dissipate into the soil.
The finished system has a water bearing capacity of 720 liter/m2 because of the soil conditions. The
system built also had to accommodate the Municipality’s garbage facility and withstand heavy loads
like trucks and containers.


Area: 340 m2

Installing the Watershell modules Inlet

Modules with steel mesh and drainage material Finished flooring

When building new housing accommodations for a municipal institute, storm water from the roof
tops and parking lots had to be collected and stored underground to accommodate infiltration.
The solution was found by building a network of Watershell infiltration units under the parking lots.
This configuration allowed the storm water to dissipate within 12 hours after collection.


Area: 550 m2

Modules installed in different configurations Column top view

Sand between the fields accelerate dissipation Project overview

During the construction of a sub division the contractor had to build an infiltration system. The
object of the system was to create water balance between pre- and post-development stage. After
completion of the infiltration system the contractor used the concrete surface as a parking lot and
area to store material. In the end phase of the project the system was covered with a park and a
square keeping the system accessible.


Area: 100 m2

Manhole cover for accessibility and to collect water CCTV-inspection of the infiltration system
samples

Images taken from inside the system Images of the Watershell modules

This municipality built a storm water infiltration system under a large square. The system is constantly
monitored and the water quality is tested at regular intervals. A key component of monitoring is a
CCTV inspection. The system can be accessed via a manhole cover and the camera can be lowered
into the system. This infiltration system was built underneath a basketball court.


Area: 450 m2

Installing modules on a crushed lava stone foundation Drainage material as a perimeter

Infiltration system is the foundation for a bicycle path Pouring concrete

In a new suburb development the Municipality had a railway system installed. The storm water
collected on the roof and parking areas around the railway cannot be connected to the sewer system
or dumped into open water. The storm water is redirected into the Watershell system and a crushed
lava rock foundation doubles as a filter system for the runoff water. This purified water can dissipate
into the sub soil without causing an environmental risk.


Area: 750 m2

Positioning of the modules Materials storage

Sand in between the systems Pouring concrete

Within this Municipality it is mandatory to compensate the amount of impermeable surface area due
to construction of roads, parking lots or buildings by creating underground storm water storage. This
water has to be used to replenish the ground water table. The system was constructed 1.6 m below
the surface to accommodate a gravitational flow of storm water into the system. The system doubles
as a ground water drainage system in Winter and an infiltration system in Summer.


Principal: Church
Area: 113 m2

Positioning the modules Installing the rebar mesh

Infiltration system on the church grounds Cross section of the Watershell system

The Bishopdom requested a solution for their storm water problem. Water that came off of the roof
of the Cathedral contained large quantities of lead and copper elements. The church was required
to filter this polluted water and try and infiltrate the clean water into the sub soils. The solution
was found by placing the Watershell system on a foundation of crushed lava rock. The lava has
an excellent filter quality. The polluted storm water runs into the infiltration system and the water is
purified. The system was built underneath the church’s lawn.


Principal: Land Developer
Area: 2,050 m2

Digging the trench Installing the Watershell modules on a geotextile

Installing the reinforcement mesh System is ready for concrete pouring

A Land Development Company was building its office and maintenance buildings on 7.4 acres. To
comply with the municipal by-laws concerning urban runoff water the Land Developer had to build
a storm water infiltration system large enough to contain 800 m3 of runoff water. The contractor
wanted three separate infiltration systems each suitable for bearing heavy loads. Two systems of
240 m3 each and one system of 318 m3 were built. Each system has an overflow in case it exceeds
the maximum water bearing capacity. The overflow is forced out of the system and flows over the
road into the sewer system. This method of monitoring was chosen so it would be easily detected
when an overflow occurred.


3 Infiltration Field - Work Description
3 Infiltration Field - Work Description

3.1 Preparation

Surveying specifications and considerations:

• Use the most recent version of Call-Before-You-Dig data to localize any underground utility
infrastructure.
• Investigate load bearing capacity of the excavation for construction’s sub base and improve soil
conditions and/ or change construction to specification
• Investigate soil permeability conditions to calculate the hydraulic conductivity (K) of the soil and
dissipating speed
• Investigate groundwater conditions; to guarantee maximum infiltration field capacity, the system
has to be build above average groundwater level (GWL)

Installing:

• Excavation for construction’s outer measurement is 0.50 m wider than outer measurements of
the Watershell infiltration field
• Length (L) and width (W) of the infiltration field are in multiples of 0.50 m + 0.12 m.
These 0.12 m consist of the modules’ rims (2 x 0.02 m) and XPE-foam (2 x 0.04 m) on the outer
edges of the field
• Module height is variable, e.g. 27, 35, 40 and 45 cm
• Pouring concrete thickness and quality vary dependant on load bearing capacity needs and
ground cover
• The steel rebar mesh used is equally spaced crossed bars with a 6-100-100 mm diameter, but
can differ according to specification of the engineered construction and/ or the producer of the
steel mesh reinforcement.


3 Infiltration Fields - Work Description

Fig.10: cross-section oF the inFiltration Field

Fig.11: top view oF the inFiltration Field


3.2 Geotextile installation

The recommended geotextile Mirafi® HP370 or HP570 is installed on a sufficiently load bearing and
water permeable floor. This floor is fully prepared and equalized on the engineered depth with ± 1 cm
allowance. The total area of the geotextile is Length x Width (LxW) plus 4x Height of the XPE foam
board plus 0.5 m on every side. This way an overlap is created on the perimeter of the infiltration
field, thus avoiding sand leaching into the field (fig.12).

Fig.12: geotextile’s overlap around outer tiles and xpe FoaM board

3.3 Tile installation

The concrete tile’s thickness can vary from 45 mm to 80 mm dependant on the required load bearing
capacity of the infiltration field. The centre of the first tile is installed at the corner of the first Watershell
module, overlapping length and width wise (fig.2). Install tiles centre to centre every 50 cm. TIP: use a
piece of cut to size board as a spacer template. On location of the inlet pipe tiles have to be installed
connected forming a solid apron of at least 1 m2, thus preventing leaching of sand (fig.13).

Fig.13: the bottoM right corner oF the systeM shows connected tiles at the site oF the inlet


3.4 Module installation

Install modules from left to right, pointing the arrows on the modules in the same direction. Follow
the modules’ indicated installation plan. Pay special attention to assembling the legs of the modules,
they should always interlock.

Fig.14: Modules installation plan, leFt to right, arrows in one direction

3.5 Concrete reinforcement installation

Steel mesh reinforcement (Ø 6 x 100 x 100 mm) is installed using spacers on top of the modules with
a minimum of 250 mm overlap. If the infiltration field is subject to high traffic loads and ground cover
is limited, reinforcement of corner and or rim modules is advisable. After the installation of the steel
mesh, the structure is more stable and easier to walk on. The XPE board is installed after installing
the steel mesh. The steel mesh needs a spacing of 40 mm in reference to the XPE board to ensure
sufficient concrete cover on the perimeter (fig.15).

Fig.15: spacing oF the steel Mesh in reFerence to the xpe board with geotextile


3.6 XPE board installation

The XPE board ensures water is infiltrated into the surrounding soil and prevents sand leaching into
the system. XPE board is an essential part of the Watershell system and can not be replaced by other
materials. XPE board consists of recycled expanded polystyrene with a thin layer of geotextile on
one side and a green reinforcement mesh on the other. Its length is 1000 mm and its height varies
dependant on the height of the system (module’s height + concrete cover). Its thickness is 40 mm.
The green mesh side of the XPE board is installed on the outside of the field, the joints are installed
at the leg/ column of the modules, thus ensuring maximum earth pressure resistance (fig.16).

Fig.16: installing oF the xpe board’s joints at the Module’s coluMn

As mentioned in chapter 2, the geotextile around the system is installed around the outer tiles and
between the XPE boards and the modules. Modules on one side and sand footing on the outside
support the XPE boards. Just use your feet to create the sand footing (fig.17).

Fig.17: xpe board, green Mesh on the outside, supported by sand Footing


3.7 Installing inlet/ outlet pipes and inspection manholes

After installing the XPE board barrier connecting pipes and holes are installed. The system can
include inlet, outlet, de-aeration/ venting and overflow pipes. To seal of pipes and XPE board a
combination of polyurethane foam and concrete is used. An XPE board box is placed around the
pipe entrance spaced at 15 cm and sealed of with foam forming formwork to be filled with concrete.
This creates extra stability around the pipe’s inlet/ outlet (fig.18).

Fig.18: installing ForMwork For pipe inlets/ outlets

For easy access and inspection, formwork holes are installed in the system’s concrete cover to
accommodate manholes, see fig.19. Inspection and maintenance are essential characteristics of the
Watershell Infiltration fields.

Fig.19: Manhole For visual inspection and systeM Maintenance


3.8 Backfill

First backfill the perimeter to half the modules’ height to prevent shifting of the modules, then loosely
backfill to the rim of the XPE board. Walking on the systems backfill at this stage is strongly advised
against, the modules could shift. Backfill material is water permeable sand (fig.20).

Fig.20: loosely backFilled periMeter prior to concrete pouring

3.9 Concrete specification

After backfilling the side face, concrete can be poured into the structure. It is important to calculate
the concrete amount needed to completely fill up the system’s columns formed by the module’s legs
and the concrete top cover. Essential attributes of the concrete are:

Concrete specification for Watershell modules (Atlantis excluded):

Strength: C20/25
Grade S3 plasticity
Granular stone Ø 4 – 32 mm with Dmax Ø = 32 mm
Chloride grade CL 0.40 reinforced concrete

The concrete cover varies in thickness, steel mesh and concrete quality dependant on environment,
loading and geometry of the construction. Expansion joints have to be taken into account, follow the
structural engineer’s directions. Contact your local Watershell supplier for more information and/ or
engineering questions.

The amount (m3 per m2) of concrete needed to fill the formworks’ columns to the top of the modules
depends on the modules’ height. Table 2 depicts the amount of concrete in cubic meters needed
with various Watershell modules, excluding the amount needed for the concrete cover.


Watershell height cm Concrete amount m3

27 0.040
35 0.056
40 0.060
45 0.065

table 2: concrete aMount per watershell height cM

Work from the centre of the floor outwards concentrically (fig.21). When using a concrete pump
make sure the flow is slow and consistent, preferably using the hose horizontally. Finish the floor with
a trowel. Make sure to avoid shrinkage of the concrete floor after pouring.

Fig.21: concreting the coluMns concrete pouring pattern


3 Infiltration Fields - Step by Step Work Description

1. Excavate the area needed to build the system, use a 2. Install geotextile and space the concrete tiles
compacted layer of sand for adequate load bearing according to specification
capacity.

3. The Watershell System must be positioned with the 4. The XPE drainage mat is placed around the perimeter
columns on the tiles. and secured in place with sand.

5. The woven geotextile must be wrapped around the 6. The steel reinforcement mesh is placed on top of
XPE mat. spacers before concrete pouring.


3 Infiltration Fields - Step by Step Work Description

7. Inlets and outlets are created using the XPE board 8. Backfill the perimeter with sand and compact lightly.
to box in the pipes. In the detention system create an
apron with tiles at the inlet’s position.

9. Pour the concrete on the modules at a controlled rate 10. Fill the columns with concrete.
either with a concrete pump or excavator.

11. Trowel the concrete to create a smooth surface.
The system is ready for use after the concrete has
hardened.


4 Infiltration Cellar - Summary
Sustainable development strategies are of great Infiltration cellar advantages:
influence in new developments, constructions
and restructuring projects. Communities— • Simple and fast installation
large and small, rural and urban—are facing • Accessibility
many challenges associated with sustainable • Inspectable and cleanable
development, whether building houses, office • High load bearing capacity
buildings, industrial areas or infrastructure • No need for ground backfill
projects. The underground construction of • Variable height, length and width
infiltration cellars may help to meet a number of • High volume storage capacity
challenges. Runoff water is temporarily stored • Relatively low costs
in the Watershell system and can dissipate • Multiple space plan
either back into the soil, the sewer system or • Large infiltrating surface area
surface water at a controlled rate. Infiltration • Great expertise and many reference projects
cellars’ application possibilities are endless, for
example beneath parking lots, squares, roads
and green belts.

Watershell load bearing concrete thickness outer height water
Notices, please consider: type capacity D. floor D. tile mm bearing
kN mm mm capacity
• Connected surfaces m3/m2
• Runoff water quality Atlantis 1250 450 120 120 0.682
• Peak rainfall quantity Atlantis 1250 600 0 150 0.634
• Ground water level (GWL) Atlantis 1250 450 120 120 0.923
• Effluent rate Atlantis 1250 600 0 150 0.875
• Sediment or leaf traps Atlantis 1250 450 120 120 1.163
• Available area Atlantis 1250 600 0 150 1.115
• Traffic load Atlantis 1250 450 120 120 1.404
• Ground cover/backfill Atlantis 1250 600 0 150 1.356
• Allowed earth pressure Atlantis 1250 450 120 120 1.644
Atlantis 1250 600 0 150 1.596
Values are based on 600 mm ground coverage, Ø 8 x 150 x 150 steel mesh reinforcement and
sufficient load bearing capacity of the systems floor. Ground coverage of less than 600 mm can
influence reinforcement and/ or concrete D values. Please contact your local Watershell system
supplier for more information and/ or engineering questions.


4 Infiltration Cellar - Projects
Principal: Shipping Company
Area: 783 m2
Material: Watershell Atlantis

Positioning the modules Overview system

XPE Drainage material installed along perimeter Pouring concrete

A shipping company needed to build a large retention buffer on their premises. The contractor build
a cellar to retain storm water from roads and roofs. The storm water is buffered for a short period and
then disposed off via the storm sewer system. The cellar was built to accommodate 925 m3 of storm
water to avoid water problems during a rain cycle. The cellar has an external height of 1.5 m and the
sides were created using L-shaped retaining walls with XPE RT35 drainage mat around the whole
perimeter. The mat was used as an infiltration layer to replenish the surrounding soil. Watershell
Atlantis was placed on a concrete floor without rebar. The system was built with a 12 cm concrete cover.
The chamber was built under the company’s parking lot and has a 600 kN load bearing capacity,
which is comparable to a traffic load of a truck with three axles weighing 200 kN each.


Area: 350 m2

L-shaped retainer walls and concrete floor Manhole with sedimentation trap and controlled effluent

Overview infiltration chamber Overview after installing the modules

Near a retirement home a large infiltration system was built underneath the access road. The system
has a capacity of 380 m3 and a Nett water bearing capacity of 1,086 ltr/m2. The Watershell Atlantis
system was built on a reinforced concrete floor between a 1.5 m high retaining wall. The concrete
cover of the system was constructed using 12 cm of reinforced concrete. On the system a 95 cm
layer of sand was used to create a load bearing capacity of 600 kN. The retaining wall perimeter
wasn’t placed watertight so the drainage mat could accommodate water flow to the surrounding
soil. The cellar also has a water flow regulating system to have a controlled effluent to the regular
storm water sewer system. By creating a storm water cellar this way the principal has a system that
can accommodate large amounts of storm water and an acceptable dissipating rate. The cellar can
be accessed via a manhole for inspection and cleaning.


Area: 372 m2

Watershell Atlantis modules and retaining wall Water flow via the spacing of the retainer wall

Pipe lines going into the chamber Inside view of the system

The first infiltration cellar was constructed for a Municipality. This newly developed infiltration system
was used in a suburb. The storm water drains from roads and roof tops are collected and directed
towards the cellar that has a water bearing capacity of 600 m³ and only takes up 372 m². This results
in capacity of 1,620 ltr/m². The system was built using the Watershell Atlantis. This system also has
a high load bearing. The perimeter was created using water pervious prefab concrete elements. The
floor of the cellar consists of a permeable layer connected to a gravel sub layer. Infiltration is possible
via the bottom of the system. The biggest advantages of this type of system are the accessibility
via a manhole cover and the possibility of cleaning the system if needed. The internal height of the
system is 1.7 m (5.5 feet).


Area: 992 m2

Installing modules Modules, PVC columns and tiles

Overview system Concrete and inspection manholes

This large storm water infiltration system was built to divert storm water from the surrounding
buildings and keep the water out of the sewer system. The system consists of the Watershell Atlantis
modules stacked on PVC columns to create a large underground cavity and still be cleanable and
inspectable. Accessibility of the system is via a manhole. The project was constructed as a joint
venture between the contractor and the supplier. The perimeter was built using XPE drainage board
material. Another option to build the perimeter is using pre-fabricated concrete forms. This system
can withstand traffic loads up to 200 kN.


Area: 212 m2

Positioning of the retainer wall Pouring of the concrete floor (no reinforcement)

Installing the Watershell system Pouring of the concrete cover on the modules

This infiltration cellar was built as a result of a reconstruction of a large above ground parking lot.
This project required a storm water infiltration system that could double as a parking lot. This meant
that the concrete cover of the cellar must be able to withstand the load of the parked vehicles. The
storm water from the parking lot and surrounding buildings is diverted into the cellar and from there
it infiltrates into the soil at a controlled rate. Eventually two systems of 150 m³ each were built within
a week.


5 Water Storage Cellar - Summary
Just like infiltration fields and cellars, Water Water Storage Cellar advantages:
Storage Cellars may help to meet a number of
requirements and challenges associated with • Simple and quick installation process
sustainable development, whether building • Accessibility
houses, office buildings, industrial areas or • Inspectable and cleanable
infrastructure projects. Water is temporarily • High load bearing capacity
buffered and slowly dissipated to either sewer • No need for ground backfill
systems or open water. Application possibilities • Variable height, length and width
are endless, for example beneath green houses, • High volume storage capacity
as sprinkler system water buffer beneath (sports) • Relatively low costs
parks and office buildings. • Multiple space plan
• Great expertise and many reference projects

Notices, please consider: Watershell outer H inner H Traffic load D concrete water
type mm mm kN cover bearing
• Required storage volume mm capacity
• Ground water level (GWL) m3/m2
• Effluent rate Atlantis 1200 880 450 120 0.798
• Inlet amenities Atlantis 1200 850 00 150 0.769
• Outlet amenities Atlantis 1600 1280 450 120 1.182
• Access amenities Atlantis 1600 1250 00 150 1.154
• Available area Atlantis 2000 1680 450 120 1.567
• Traffic load Atlantis 2000 1650 00 150 1.538
• Ground cover/backfill Atlantis 2280 (max) 1960 450 120 1.837
• Allowed earth pressure Atlantis 2310 (max) 1960 00 150 1.837
Values are based on 600 mm ground coverage, Ø 8 x 150 x 150 steel mesh reinforcement and
sufficient load bearing capacity of the systems floor. Ground coverage of less than 600 mm can
influence reinforcement and/ or concrete D values. Please contact your local Watershell system
supplier for more information and/ or engineering questions.


5 Water Storage Cellar - Projects
Area: 2,225 m2

Installing Watershell against the concrete perimeter 2,225 m2 of modules with steel mesh reinforcement

Pouring concrete Sports field on the 630 m3 water detention cellar

During the redevelopment of an old industrial factory the Municipality wanted to build a park. They
devised a totally new concept for dealing with storm water by building a large 630 m³ storage cellar
under a sports field. By building the cellar under the field the Municipality was able reduce building
costs considerably but also solve a storm water issue. The main advantage for the field was that it
wouldn’t be affected by soil settlement.


Principal: Rose nursery
Area: 1,350 m2
Water bearing capacity: 1,200 m3

Positioning Watershell modules in concrete culvert Concrete floor under the modules

Watershell system based on arches and columns Pouring of the concrete

A Rose nursery needed a large storm water detention system to collect rain water runoff of their green
house. The system had to be able to detain 1,200 m³ of water and the available space was 1,350m².
The detention cellar also doubled as the foundation for the green house. Storm water is collected
and treated and then reused as irrigation for the plants. Research has proven that underground
storage of water results in better water quality, because of the lack of UV light and a constant water
temperature. The potential for algae growth is very low.


Area: 620 m2

Concrete floor and walls Building the test site

Top view test site Filling the columns with concrete

This cellar is used as a temporary storm water detention unit. The water is eventually pumped and
dispersed. During the build a test site was created to test the filling of the columns with concrete.
By using transparent pipes a visual inspection was possible. After hardening the pipes were cut and
tested to see how well the pipes were filled and how well compaction was achieved.


Area: 330 m2

Excavation for the water detention system Pouring of the flooring

Installing the hollow walls Installing the modules

A 550 m³ storm water detention cellar was built under a bicycle path. This path will also double as
a road for heavy traffic. Storm water from roof tops and the surrounding streets is collected and
then pumped at a controlled rate to open water. The cellar doubled as the foundation for the road
and bicycle path and has an internal size of 2.5 m x 130 m. (width x length). The walls are based on
hollow wall technology which means they have a cavity between the outer and inner shell.


Area: 308 m2

Floor with gutter Installing the Watershell Atlantis modules

Watertight concrete walls Pouring of the concrete cover of the system

In a suburb a Municipality wanted to create a storm water detention system to buffer the peak
amount and have it dissipate at a controlled rate. This meant the sewer system would be relieved of
the excess water. The natural soil was impervious so infiltration wasn’t a viable option. The stored
storm water would then be pumped up and dispersed into the nearby stream at an acceptable
rate.


Principal: Home Owner
Area: 55 m2
Load bearing capacity: 4 kN/m2

Installing modules on concrete floor Installing of the modules

After installation Project’s location

This water detention system was built on a home owner’s premises. As this area has a water
deficiency this home owner decided to build a storm water detention system to reuse the storm
water to irrigate the garden, flush toilets and wash the car.


Principal: Bus Company
Area: 140 m2

Installing modules Side view during installation

Close up of the modules against the concrete wall After positioning the system before pouring concrete

Storm water from the roof of one of the large buildings is redirected to the detention cellar. This water
is used to wash the busses. A bus washing facility was constructed on top of the detention cellar.


Principal: Akzo Nobel Factory
Area: 460 m2

Installing the modules in the concrete culvert Cellar’s dimensions are 57.5 x 8 m

Finished roof of the system, top view Accessibility to pump unit (capacity 30 m3/hour)

This project is a 700 m³ detention cellar built to accommodate storm water runoff from the surrounding
industrial area. The cellar was built under a major road running between buildings. Storm water from
roofs and roads are collected and dumped into the cellar using gravitational force. The water is then
transported over a distance of 600 meters and pumped into an open body of water. The pump has
a capacity of 30 m³/hour. The alternative to the cellar would have been a pond, but that would have
meant they needed about 3,200 m² of open space to dig it. The cellar saved space and could be
capitalized on because it was still usable space. This proved to be the most economical solution to
the question at hand.


Principal: Green house nursery
Area: 550 m2

Floor has been poured Concrete walls are ready

Installing the Watershell Atlantis system System ready for concrete pouring

The farmer chose to build a storm water detention system that can detain runoff water from the roof
of the green house and use it to irrigate the plants. By building a cellar they could create the needed
water storage without using valuable outside space. A pond or large tank would have been the
normal alternative. The water in the cellar is of very high quality and at constant temperature which
means no additional energy is needed to keep the water at a desired temperature.


Area: 355 m2

Empty concrete culvert with floor and walls Installing the Atlantis modules

Ready for concrete pouring Pouring concrete

This storm water cellar was build directly beneath the surface and was designed to detain storm
water so it could flow into the storm water sewer system at a controlled rate. The system is solely
based on gravitational flow. This provided the Municipality with an inexpensive method of storm
water management. The system was built under a road and is L-shaped.


6 Root Bridge - Summary
Cracked pavements, uprooted tree grates and Root Bridge Advantages:
turf paving can be hazardous for pedestrians,
bikers and traffic. Tree roots need air as well as • Simple and fast installation
water, which is why these roots search for cracks • Second grade on top of root system
in the pavement where rain or condensation form • Air pockets prevent uprooting
pockets and so cause damage to surrounding • High load bearing capacity (H20)
infrastructure. The Watershell root bridge • No ground cover necessary
application offers the solution to the root growth • Variable sizes, L x W x H
problems for mature as well as newly planted • Relatively low costs
trees by creating a second grade on top of the • Great aeration and watering
roots. An air pocket is constructed beneath • Finish concrete covers with variable designs
the pavement forming this second grade, thus • Great expertise and many reference projects
providing roots with enough air and water to
survive the harsh conditions of urban areas. A
Watershell root bridge prevents uprooting and
creates durable smooth surfaces to safely walk
and bike on.

Notices, please consider: Root bridges have no standard solutions. The concrete
cover needed is dependant on several variables and should
• Aeration be engineered for every system. On top of the concrete
• Irrigation / watering cover a diversity of paving can be used such as tiles, stone,
• Excavation depth asphalt, concrete printing or a layer of ground backfill. To
• Available space calculate the amount of reinforcement and concrete cover
• Traffic load thickness needed per system please contact your local
Watershell system supplier for more information.
• Backfill
• Allowable earth pressure


6 Root Bridges - Projects
Area: 100 m2
Water bearing capacity: n/a

Leveling soil around the tree Watershell system spaced around the tree

Paving consisting of natural stone Chestnut tree after completion of the project

In a Cultural park the Municipality wanted to preserve a heritage chestnut tree. The tree was in the
centre of the park and paving was going to be installed all around the tree. To provide the roots the
space to grow and still provide the necessary water and air the Municipality chose to use the root
bridge system. A water and aeration drain pipe provides the optimal environment for the roots.


Area: 70 m2

Installing the 8 cm high Watershell modules Concrete paving with stone print

Entrance to the building Sustainable root free driveway

A former military base in the center of the city was adapted to create living and working areas. The
entrance was a combination of heritage buildings and new construction with two heritage trees
flanking the driveway. The trees had to be preserved to maintain the natural landscaping around the
base. To prevent root damage to the driveway the Municipality constructed a root bridge system
using Watershell. The Watershell modules created a second layer on top of the roots to provide them
with the ability to grow without causing damage to the surrounding infrastructure. They used a stone
print in the concrete for maintenance free and sustainable paving.


Area: 225 m2
Material: Watershell 12 Modules

Spacers and rebar Modules on a foundation of concrete tiles

Watershell used as a road foundation Overview of the project

During a restructuring of a road near a railroad track the Municipality wanted to preserve an old tree.
The tree was located to near to the new road and could cause problems in the future. They decided
to create a root bridge system to provide the roots the space to grow with sufficient water and air.
The system was built using the Watershell 12 modules and a concrete cover.


Area: 355 m2

Installing the Watershell modules Modules with steel mesh on concrete tiles 50 cm center to
center

System overview before pouring concrete Root bridge after completion with a steel guard rail

The Municipality wanted to prevent tree roots from damaging the bicycle path after restructuring. They
estimated that the abutting four large trees would cause damage to the cycle path. By constructing a
root bridge they were able to prevent damage and thus save on maintenance costs in the future.


7 Tree Environment Protection - Summary
Trees in urban areas grow in harsh conditions. Tree Environment Protection Advantages:
The underground and infrastructure conflicts
with the root growth and thus with the well being • Create a large space for the roots to grow
of the trees. The surrounding soil is heavily • Less maintenance of infrastructures
compacted by traffic and the roots have difficulty • Aeration layer prevents upward root growth
reaching water or getting air. With the Watershell • Aeration and irrigation of roots
system a tree environment can be created that • Roots accessible for sampling
suits its needs. When building the system a • Easy and fast construction
layer consisting of concrete is constructed. The • Create a second layer on top of the roots
soil under this layer will not compact and the • Aeration layer prevents pressure on the roots
roots have the ability to grow without causing • High load baring capacity (H20 loading)
damage. The space underneath the concrete • No backfill needed
cover is filled with soil with sufficient nutrients • Variable in size (LxWxH)
for the tree. The system itself is constructed as • For newly planted and old trees
a growth layer and the tree can flourish with no • Relatively low construction costs
limitations during its life. • Great expertise and many reference projects

Notices, please consider: Watershell Traffic Load D tile D concrete H outer Soil
type kN mm cover mm capacity
• Aeration mm m3/m2
• Irrigation / watering Watershell 55 450 80 120 750 0.495
• Ground water level (G.W.L.) Watershell 55 600 80 0 770 0.495
• Available space Atlantis 450 80 120 900 0.571
• Traffic Load Atlantis 600 80 0 900 0.551
• Allowable earth pressure Atlantis 450 80 120 1100 0.763
• Soil consistency Atlantis 600 80 0 1100 0.744
Atlantis 450 80 120 1300 0.955
Atlantis 600 80 0 1300 0.936
Values are based on Ø 8 x 150 x 150 steel mesh reinforcement and sufficient load bearing
capacity of the system’s floor. Please contact your local Watershell system supplier for more
information and/ or engineering questions.


7 Tree Environment Protection - Projects
Area: 1,530 m2
Capacity: 430 ltr of soil per m2

Installing the Modules with the cutouts Using a jig to fill the modules with soil

Tree planting location defined Tree environment protection system with XPE board
perimeter

When reconstructing a road in the Municipality they planted hundreds of new trees. The space in
which the tree roots can grow is often limited. By using the Watershell system around the tree base
and partly under the new road the roots were given sufficient space to grow without causing damage
to the road or utilities. This will enhance the tree’s life expectancy. Humus was filled between the
Watershell modules and the concrete top layer was poured to cover the system. This method of
construction also benefited the road as the shoulder was reinforced through the concrete layer.


Area: 600 m2
Material: Watershell 16 Atlantis

Using vacuum excavation to expose the roots Installing PVC columns on a tile foundation and installing
drains

Installing the Watershell modules Concrete top layer as foundation for path made from broken
shells

Due to the intensity of traffic traveling over the shell path the surrounding soil was compacted to
densely for the tree roots. The tree’s growth was seriously in danger. By using the Watershell as a
tree environment protection system the life expectancy of the trees has been extended. Some of the
trees are over 150 years old. The concrete top layer of the Watershell system is now the load bearing
system and compaction of the surrounding soil is no longer an issue. By using vacuum excavation
on this project the tree roots weren’t damaged during construction. The perforated concrete layer
on top now allows rainwater to get to the roots and the drain pipe placed between the roots before
backfilling is an ideal aeration system.


Area: 1,350 m2
Material: Watershell 16 Atlantis, outer height
system 90 cm (35 inches)

Installing PVC columns on a tile foundation Soil under the modules

Formwork for planting the trees Tree planting space after concrete pouring concrete

This reconstruction project is situated in an urban area with sub surface ground and above ground
infrastructure. To obtain sufficient sub surface space for the trees to grow the Municipality chose to
use the Watershell Atlantis system. The project was constructed in different stages and consisted of
1,350 m2 of the Watershell Atlantis system. This meant they needed 5,400 Watershell modules and
7,200 PVC columns with a height of 74 cm (29 inches). The system contains 750 liters of soil per
square meter and within this layer water drains and air drains have been installed to provide the roots
with the necessary air and water. On the 12 cm (4.7 inch) concrete top layer the contractor installed
a natural stone that can withstand loads up to 450 kN. This system provides the roots the space to
grow and the 10 cm (4 inch) space between the concrete top layer and the soil layer functions as a
natural root pressure barrier.


Area: 1,300 m2
Capacity: 1,430 ltr of soil per m2

Installing PVC columns Backfilling with soil

Watershell Atlantis on the PVC columns Overview of the end result

The first Tree Environment Protection project was completed in 2001. In a large city the system was
installed next to a streetcar rail under the streetcar stop. This was done to create a space for the
newly planted trees to grow. Every tree had approximately 50 m³ of soil to grow in. The soil has a
low load bearing capacity so the Watershell system had to cope with the loads to stop the soil from
being compacted. This system has proven to be the right step towards tree care.


Area: 172.5 m2

Installing the tile foundation and column base Backfilling the soil, columns are temporarily
supports capped

Installing the Watershell Atlantis modules Formwork around the inspection manhole

In a city center five tree environment protection systems were installed. The main arguments to do
this were that the soil layer wouldn’t compacted, the cobble stone paving wouldn’t get damaged
over time and the costs for installation were relatively low. Root pressure and collapsing and/ or
compacting soil are the most damaging factors for cobble stone pavements.


Area: 400 m2

Installation of the PVC columns on concrete Modules with formwork around the tree
foundation planting area

Pouring concrete on the modules Project overview

The Municipality wanted to create a new city plaza and plant 18 Lime trees. The problem the
Municipality had with just planting trees the traditional way was that they expected continued
compaction of the soil and that would lead to settlement of the plaza paving. The settlement would
cause high maintenance costs. The Watershell system was strong enough to bear the load of traffic
in the plaza and create the tree root protection needed. The trees would now have the life expectancy
the Municipality was looking for. Each tree had approximately 30 m³ of soil to grow in. The whole
project was completed within a two month period.


Area: 750 m2

Project overview Overview with tree planting spaces

Irrigation system was installed An 11 cm (4.3 inches) space between the soil
and the bottom of the Watershell modules

New trees are planted in a reconstructed shopping center plaza. To guarantee the life expectancy
of the trees the Municipality placed the Watershell system around the planting areas. This plaza
has heavy traffic load from trucks bringing supplies to the different stores. These loads would have
resulted in compaction of the surrounding soil. The Municipality also wanted an irrigation system
within the Watershell modules. The irrigation was installed just underneath the modules on top of
the soil. This open space is also ideal for aerating the roots. In total 33 trees are planted using the
Watershell Tree Environment Protection System.


Watershell Catalogue Specto Ct August 2009

Watershell Catalogue Specto Ct August 2009

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