Installation Tips and Guide.
Copyright 11/2007. Northstar Vinyl Products, LLC. All Rights Reserved.
IMP ORTA NT NOTI CE
This Guide is purposely intended to be general in scope. It is meant to educate a sophisticated user
and builder of retaining walls on the finer points of constructing a sheet pile retaining wall using the
AquaTerra System which feature Northstar Synthetic Sheet Piling. This Guide does not contemplate
every condition that may be encountered, but rather serves as a baseline for understanding the
construction methodology. Inexperienced users are highly encouraged to gain a thorough
understanding of soils and the backfill compaction process before attempting to build a retaining
No warranty, either expressed or implied, is made herein to the suitability of this system or its
individual components for your project. Always defer to the recommendations of the engineer of
record, as this individual will have a more complete understanding of specific site conditions that
may affect the application.
Some of the techniques herein are considered the intellectual property of Northstar Vinyl Products,
LLC and/or Tensar International Corporation and may not be duplicated.
Northstar Vinyl Products, LLC and The Tensar International Corporation offer technical support and
can also arrange to provide you with signed and sealed engineering drawings for your project. If you
are interested in this support, please contact your Northstar or Tensar Representative.
One feature of the AquaTerra System is that Northstar’s sheet piling can either be driven
into soil or set in a trench. This Guide instructs on methods using a trench.
PHASES OF CONSTRUC TION
Setting Driving Guide
Preparing the AquaTerra GridSpines and Setting Sheet Piling
Preparing and Installing the Geogrid Reinforcements
Using conventional trenching equipment and
methods, prepared a trench at least 12” in
width and to a depth required by the
The wall line is along the front “finished”
wall of the trench.
When digging the trench, attempt to
Check the grade. Use crusher run or other
similar material to level the trench. Fig 1.1. The Battering Brace attaches quickly
to the Outrigger.
You are now ready to set Driving Guide into
The driving guide is temporary and mobile.
As you complete sections of the wall, you
can move the guide to the next location.
SETTING THE DRI VING GUIDE
Northstar suggests that you have enough
The installation of the driving guide is a
driving guide on hand to build at least 100
very important step in the process of
feet of driving guide at a time, as building
installing an AquaTerra wall. Once it is in
in 100-foot increments is an economical
place, setting the panels is extremely
1. Install the Uprights (3” steel pipes)
Northstar has devised an innovative and
on 12’ centers on the “finished” side of the
proprietary method for installing the sheet
trench wall. The placement of the uprights
piling and maintaining a positive batter in
should be approximately 10” from the
the wall. Although many of the components
trench wall and should be embedded 50%
are available locally, if needed, Northstar
deeper than the trench. Additional
can supply the components of the driving
embedment is required if the soil is weak.
guide. The Driving Guide is made up of
upright poles, Outriggers, Staging Arm, and
Battering Braces. (Figs 1 and 1.1)
Fig 1. The Outrigger Attachment and Upright Fig 2 Install Uprights forward of the trench wall.
PREPARING T HE A QUATERR A
2. Attach the Staging Arm on the GRIDSPINE AN D SETTIN G THE SHEET
Uprights. The Staging Arms are nothing PILING
more than a beam where sheet piling “rest”
after they are installed in the trench. While Sheet piling is a very popular construction
the sheet pilings are in a temporary item in the marine and heavy construction
position against the Staging Arms, they in a industries. Long sections of sheet piling are
slight negative batter position. (Fig 3.) hoisted and set into driving position using
cranes or long-reach excavators. Many
landscape contractors who are accustomed
to installing segmental block walls do not
own or have access to this type of
equipment and for this reason may be wary
of installing long sections of sheet piling.
The AquaTerra System was designed to
alleviate the need for cranes and long-reach
By design, sheet piling used in an
AquaTerra wall are about 45% shorter than
sheet piling that has to be driven in similar
applications. This benefit alone reduces
equipment requirements on a project. In
addition, if you have a bucket lift, the
Fig 3. Install the Staging Arms. AquaTerra system eliminates the need for
having to lift the sheet piling above
previously installed panels in order to
3. Install an Outrigger on each Upright.
thread them together. Here’s how to
An Outrigger has two components - an
prepare the GridSpines and set the sheet
Adjustment Arm (Fig 1) and a Batter Brace
(Fig 10). The Adjustment Arm allows you to
set a predetermined batter in the sheet
piling. The Batter Brace will hold the panels
Preparing the GridSpines:
in an unfettered battered position as you
backfill the wall. (Fig 4) 1. Using a 1” drill bit, drill each
GridSpine 1’ from each end. (Fig 5)
Fig. 5 Drill GridSpines 1’ from each end.
Fig 4. Install the Outriggers.
6. Slide the composite rods through
the adjacent GridSpines, locking all the
Setting the Sheet Piling: panels together in one unit (Fig. 8)
Using a Bucket Lift:
1. Place two sheet piles adjacent to
one another in the trench and allow them
to rest against the Staging Arm. (Fig 6)
Fig 8. Insert composite rod through the upper
and lower holes.
7. Repeat until you reach the end of
your Driving Guide (Fig. 9)
Fig 6. Align first two sheets against Staging Arm.
2. Insert an AquaTerra GridSpine,
interlocking the two panels together. The
GridSpine will slide easily down to the
bottom of the trench.
Fig 9. All sheets are in place and resting along
the Staging Arm.
Fig 7. Insert GridSpine to join panels.
3. Insert a composite rod into the
lower and upper holes in the GridSpine.
4. Install the next pair of sheet piling in
a similar manner.
5. Check to make sure the sheet piles
are plumb and in alignment with each other.
8. Determine the adjustment to be
made to the Adjustment Arms on the
Outriggers to attain the proper starting
batter. Adjust the Batter Braces and tighten
them to the Outrigger. (Figs 10 & 11).
Fig 11. Sheet Piling is laid back against the
10. In six to ten foot increments, fill the
trench with stone, alternating the fill from
back to front. Pay close attention to insure
that the toe of the wall does not move
Fig 10. Fix the Batter Brace to Outrigger based
during this process.
on predetermined batter.
You are now ready to install the geogrid
PREPARING A ND INSTALLI NG THE
GEOGRID REIN FORCE ME NTS
It is recommended that geogrid
reinforcements be attached to the sheet pile
wall using a Tensar Bodkin connection.
A Bodkin connector (shown below) is a
plastic strip that provides a mechanical
connection to the sheet pile wall.
Fig 11. Sheet piling is now ready to be placed
in final position.
9. Once the Outriggers are in position
and Batter Braces are fixed, carefully lean
the sheet piling away from the Staging Arm
towards’ the Batter Braces on the Outrigger.
The entire unit of sheet piling should come
to rest against the Batter Braces, in their
batter position (Fig. 11).
Begin by marking (with spray paint) a line
across the backs of the sheet piling where
each grid course is located.
Using a 1” drill bit, drill each GridSpine as and “rake” the soil towards’ the
close to the spine’s “bulb” as possible. You ends of the reinforcements.
may want to drill several grid course Once the soil backfill has been
locations at one time. placed, 12” of stone should be
placed behind the wall to obtain
needed compaction and adequate
TIP: For a quick geogrid installation, you can
drainage during heavy rain events.
precut the geogrid sections and install the
Bodkin connection, leaving a loop in the end Though distances between the grid
of the geogrid section. courses may be greater, backfill in
uniform 1’ lifts.
That section of grid can then be brought to
Do not operate heavy compaction
the site, pushed against the sheet pile and
equipment within three feet of the
the connector rod slipped through the loop
in the geogrid.
Compact within three feet of the
Attach the geogrid sections to the wall on wall using handheld compaction
the immediate “working” course. equipment.
After each lift, inspect the battered
Using a pitchfork or other type of tool, position of the wall. Eventually, the
tension the geogrid and apply approximately sheet piles should begin to move
one yard of fill on the grid while it is away from the Batter Brace. You
tensioned. You can then remove the should not see much movement
pitchfork and repeat the process on the from backfilling the lower courses,
adjacent geogrid section. but may see some movement as
you approach the top elevation of
Once all geogrid sections along the working the wall.
course are in place, you can now begin After each lift, inspect the toe of the
backfilling. wall to insure it has not moved.
If there is movement at the toe,
stop the process and contact your
BAC KFILLI NG engineer for instructions.
Obtaining the proper soil compaction is
perhaps the most important aspect for
successful retaining wall construction. If
this is your first soil-reinforced wall, be sure
to have expert advice and follow proper
instructions and procedures.
Because there is comprehensive data
available from Tensar and other industry
publications, a discussion on proper backfill
techniques is not part of this Guide.
However, because AquaTerra is a unique
system, here are a few considerations:
To insure proper tensioning in the
geogrid, always start the backfilling
A 14’ wall using lightweight vinyl has zero
process by placing the soil backfill 3 deflection after being backfilled with native
feet from the back face of the wall Alabama clay.
For More Information Contact:
Northstar Vinyl Products, LLC
Tensar International Corporation
COPYRIGHT 2007. Northstar Vinyl Products, LLC. All Rights Reserved. Tensar and Bodkin
connectors are registered trademarks of Tensar International Corporation.