Appendix F: Sediment Control Measures - NZ Transport Agency

Basin Bridge Project Page | 1

Draft Construction Environmental Management Plan

Appendix F

Appendix F: Sediment Control Measures

This Appendix outlines the following:

The scope of works likely to require sedimentation control and a high level

methodology.

Description of sedimentation control measures that could be used.

Sedimentation control methodology for the pile dewatering.

F1 Scope of Sediment Control Works

The likely sources of sediment from the construction of the Basin Bridge Project can be

broken down into two key areas:

Runoff from exposed surfaces (areas of fill and re-contouring).

Contaminated groundwater from excavations (piles and trenching).

The sediment control measures for the latter are addressed specifically in Section F3

below.

The areas of fill and re-contouring vary throughout the site and include:

Fill for abutments

Fill and retaining wall adjacent to Mitsubishi Motors

Construction of new areas of road pavement

Minor retaining walls and re-contouring as part of landscape works.

Foundations for new buildings

Preparation of car parking areas for surfacing

These areas will be treated using location and task specific methodologies and are

likely to include the following controls (refer to section F2 below for further detail):

All site entrances will be stabilised to prevent the transport of sediment from the

work site on to the road

Treatment of sheet run-off down-grade of works using silt fences and / or filter

socks.

Protection of inlets to the stormwater system using filter socks and other

appropriate mechanisms.



Appendix F

F2 Description of sedimentation control measures

Some of the methods that may be used in the avoidance and treatment of sediment are

listed in Table 1 below. Further information on these techniques is attached.

Table 1 – Potential erosion and sediment control measures

Technique Use Reference Further details

Stabilise

construction

entrance

Prevent the transport of

sediment from the work

site on to the road. All

construction site

entrances will be

stabilised.

Erosion and

Sediment

Control

Guidelines for

the Wellington

Region, 2006

Attachment 1

Silt fence Treatment of sheet

runoff from construction

areas. Such areas may be

the eastern and western

abutments.

Erosion and

Sediment

Control

Guidelines for

the Wellington

Region, 2006

Attachment 2

Filter sock Treatment of sheet

runoff from construction

areas and for treatment

of stormwater prior to

discharging into Council

stormwater system.

Auckland

Regional

Council

Guideline

Attachment 3

Stormwater inlet

protection

Treatment of water

entering stormwater

collection system

Canterbury

Regional

Council Erosion

and Sediment

Control

Guideline 2007

Attachment 4

Decanting earth

bunds

Treatment of

concentrated flow off

construction areas. This

will be areas up to

3,000m2 where there is

widespread disturbance.

Erosion and

Sediment

Control

Guidelines for

the Wellington

Region, 2006

Attachment 5

Settlement tanks Treatment of water and

sediment removed in the

excavation of the piers.

Attachment 6

Geotextile

Dewatering Tube

Treatment of water and

sediment removed in the

excavation of the piers.

Attachment 7



Appendix F

F3 Sedimentation control methodology for pile dewatering

The works to construct the piles will be undertaken in four stages. The description of

work at each stage is provided below. Refer to the plans attached (SC.01 and SC.02) for

further information.

Stage 1 – Site Establishment

i. Construction area will be fenced (chain link) and site entrances established.

ii. Depending on location, site entrances will be concrete, asphaltic concrete

(existing or new construction), or stabilised in accordance with GWRC erosion

and sediment control guidelines (section 4.8).

iii. Work areas within the construction area will also be stabilised with coarse

aggregate to prevent debris being tracked out of the construction area and

onto local roads.

iv. Silt fences, will be strategically placed down grade of the immediate work site

to prevent untreated stormwater run-off from the site entering the WCC

stormwater system.

v. An excavation around the location of the pile (approx. 15m x 5m x 0.5m) will

be created to act as a containment area for cementitious material – see stage 4.

vi. A skip or bunded area will be placed/constructed on site to temporarily store

material from the pile excavation.

vii. A dewatering tube or settlement tank will be located on site to use as a method

to allow suspended sediment to settle out.

The dewatering tube (if used) will be either placed in an excavation 500mm deep,

bunded, or sit inside a silt fence or filter sock to allow treated water to slowly soak

away into the surrounding ground.

Stage 2 – Pile Excavation

Once the site has been established, excavation of the piles will commence as follows:

i. Piles will be excavated using an auger.

ii. The soil will generally be wet and will be stored in a skip or bunded area near

the excavation. The material will then be taken away to an approved land fill in

a container with sealed bottom and sides so that no wet material discharges

during transportation.

Stage 3 – Pile Cleaning

i. Prior to placing concrete, the bottom of the pile will need to be clean of all

loose/wet material. It is assumed that approximately 1m3

to 2m3

of material will

be involved in this exercise. A bucket auger will be used to remove this

material.

ii. Material will be placed in a skip or bunded area for removal to an approved

landfill at a later stage.



Appendix F

Stage 4 – Concrete Pour/Dewatering

A steel metal hopper with a pipe leading to the bottom of the pile will be used for

placing concrete under water (called a tremie). The foot of the pipe is always below the

top of the concrete in the pile and the top of the concrete in the pipe above the water

level in the pile. Placing concrete by tremie prevents the segregation of concrete. A

pump (for dewatering) will be located near the top of the pile.

Concrete will be pumped into the pile through the tremie. Ground water from the pile

will be displaced at the top. This water will be discharged/collected or treated in the

following manner:

i. By visual inspection, the clean water (from the top) will be discharged directly

to the stormwater system (bypassing mixing with any sediment laden

construction water).

ii. Dirty water not suitable for immediate discharge (as identified in the Resource

Consent, operational conditions) will be pumped to either a settlement tank or

a geotextile dewatering tube. This water will be left to let the suspended solids

settle out before discharging into the stormwater system (settlement tank), or

left to filter through the dewatering tube and into the surrounding ground (see

stage 1, item 7). The encaptured solids will be periodically removed to an

approved landfill.

The dirty water from the pile will be monitored for pH levels. Once the pH levels

reach 8.5 we will advance to step iii.

iii. Cementitious material (water with a pH greater than 8.5) will be left to flow over

the pile casing and into the excavation around the set of piles. This cement

laden water will be left to sit in the base of the excavation. Water will filter into

the ground and the cement residue will form a layer of cement paste on the top

surface. This material will be taken to an approved landfill.

Approximately 30m3 of displaced water (per pile) will be treated as a result of the

placement of concrete in the pile. It is assumed that 10m3

of displaced water will be

handled in each of operations i, ii and iii above. The size of the settlement tank and

dewatering tube will be of a size to hold at least 25m3

of displaced water.



Appendix F

Attachment 1: Stabilised Construction Entrances

Extract from Erosion and sediment control guidelines for the Wellington Region;2006,

Greater Wellington Regional Council.

4.8 Stabilised Construction Entrance

Plate 9: Stabilised construction entrance

a. Definition

A stabilised pad of aggregate on a filter cloth base located at any point where traffic

will be entering or leaving a construction site (see Figure 9).

b. Purpose

To prevent site access points from becoming sediment sources and to assist in

minimising dust generation and disturbance of areas adjacent to the road

frontage by giving a defined entry/exit point.

c. Application

Use a stabilised construction entrance at all points of construction site ingress

and egress with a construction plan limiting traffic to these entrances only.

They are particularly useful on small construction sites but can be utilised for

all projects.

d. Design

Clear the entrance and exit area of all vegetation, roots and other unsuitable

material.

Place aggregate to the specifications below (see Table 6).



Appendix F

Provide drainage to carry runoff from the stabilised construction entrance to a

sediment control measure.

Table 6: Stabilised construction entrance aggregate

Aggregate Size 50-75mm Washed Aggregate

Thickness 150mm Minimum

Length 10m Minimum

Width 4m Minimum

e. Maintenance

Maintain the stabilised construction entrance in a condition to prevent

sediment from leaving the construction site. After each rainfall inspect any

structure used to trap sediment from the stabilised construction entrance and

clean out as necessary.

When wheel washing is also required, ensure this is done on an area stabilised

with aggregate which drains to an approved sediment retention facility



Appendix F

Attachment 2: Silt Fence

Extract from Erosion and sediment control guidelines for the Wellington Region;2006.


5.3 Silt Fence

Plate 14: Silt Fence

a. Definition

A temporary barrier of woven geotextile fabric used to intercept sediment laden runoff

from small areas of soil disturbance (see Figure 20).

b. Purpose

Silt fences should only be used to intercept sheet flow. Do not use silt fences to reduce

the velocity of flows in channels or place them where they will intercept concentrated

flow.

c. Application

On low gradient sites or in confined areas where the contributing catchment is

small, i.e., short steep batter fills and around waterbodies.

To delineate the limit of disturbance on earthworks sites such as riparian areas

or bush reserves.

Do not install silt fences across waterbodies or in areas of concentrated flow.

d. Design



Appendix F

Excavate a trench minimum 100mm wide and 200mm deep) along the

proposed line of the silt fence. Install the support posts on the downslope edge

of the trench and silt fence fabric on the upslope side of the support posts to

the full depth of the trench. Backfill the trench with compacted soil.

Place supporting posts or waratahs approximately 3m apart and 0.4m deep.

Ensure the top height of the fence is 400mm above ground level.

To attach fabric, double over and fasten to the support wire and posts with wire

ties or cloth fastening clips at 150mm spacings.

Join lengths of silt fence together by doubling over fabric ends around the

supporting posts (wooden posts/battens). Staple the fabric ends to the batten

and butt two battens together.

Maximum slope lengths, spacing of returns and angles for silt fences are shown

in Table 9.

Install silt fence wings at either end projecting upslope to a sufficient height to

prevent outflanking.

Table 9 – Silt fence design criteria

Slope

(%)

Slope Length (m) Spacing of

Returns

(m)

Length (m)

<2% Unlimited NA Unlimited

2-10% 40 60 300

10-20% 30 50 230

20-33% 20 40 150

33-50% 15 30 75

>50% 6 20 40

e. Construction Considerations

Always install silt fences along the contour. Where this is not possible or where

there are long sections of silt fence, install short silt fence returns projecting

upslope from the main fence to minimise concentration of flows. Silt fence

returns are a minimum 2m in length and can incorporate a tie back. They are

constructed by continuing the silt fence around the return and doubling back,

eliminating joins.

Where impounded flow may overtop the silt fence make provision for a rip-rap

splash pad or other outlet protection device.

If water ponds behind a silt fence, provide extra support with tie backs from

the silt fence to a central stable point on the upward side. Extra support can

also be provided by stringing a wire between support stakes and connecting

the filter fabric to this wire.



Appendix F

Use supporting posts of tanalised timber (50mm x 50mm), or steel waratahs at

least 1.5m in length.

Reinforce the top of the silt fence fabric with a wire support made of galvanised

wire (minimum diameter of 2.5mm). Tension the wire using permanent wire

strainers attached to angled waratahs at the end of the silt fence.

Use of silt fences in catchments of more than 0.5 ha requires consideration of

other site control measure

f. Maintenance

Inspect silt fences at least once a week and after each rainfall.

Make any necessary repairs when bulges occur or when sediment accumulation

reaches half way up the fabric height. Remove sediment deposits as necessary

to a secure area.

Any areas of collapse, decomposition or ineffectiveness need to be

replaced.

Do not remove the silt fence until the catchment area has been stabilised.

When the silt fence is removed stabilise the area occupied by the fence.



Appendix F

Attachment 3: Filter Sock (Publication of Auckland Regional Council)



Appendix F



Appendix F



Appendix F



Appendix F



Appendix F

Attachment 4: Stormwater Inlet protection

Extract from Erosion and Sediment Control Guideline 2007- A better way of managing

earthworks and the environment. Environment Canterbury; Report No.: R06/23

7.2.6 Stormwater inlet protection

Description and purpose

Stormwater inlet sediment control devices are used to intercept and treat sediment-

laden runoff before it enters a reticulated stormwater system and before subsequent

discharge into a receiving environment. Inlet protection may take various forms

depending upon the type of inlet to be protected.

Control measures are installed in areas of concentrated flow (the roadside kerb and

channel) and will usually have to contend with significant flow velocities, although their

sediment retention efficiency is usually low. Stormwater inlet protection is, therefore, a

secondary, or supplementary sediment control measure and should not be used as a

stand-alone technique.

Accordingly, stormwater inlet protection devices must be used in conjunction with a

full range of other erosion and sediment control management practices that have been

strategically deployed in an integrated approach. Take care with these control devices

to ensure that they do not cause secondary flooding: their aim is to remove as much

sediment as possible from site runoff and allow water to flow past the retention

measure to enter the stormwater system further downhill.

Where to use it

DO use stormwater inlet sediment control devices as an integral component of a

much broader and more comprehensive erosion and sediment control system.

DO use on areas with low sediment yields and runoff volume.



Appendix F

DON’T completely block the storm drain system; always include a bypass arrangement.

DON’T use straw bales in roadside water tables or around stormwater inlets because

they

are easily broken and straw can block the inlet to the stormwater system.

DON’T use sediment fencing around stormwater inlets.

Limitations

Stormwater inlet protection:

is only useful in very small catchments;

should not be used as a stand-alone technique (although at times this is

navoidable);

measures have relatively low sediment removal efficiency and low hydraulic

capacity;

measures have very limited sediment storage capacity; extremely high

maintenance requirements;

measures and/or debris may partially block the stormwater system, increasing

the likelihood of localised flooding;

often leaks, particularly against the kerb;

measures may cause stormwater and sediments to pond on footpaths,

carriageways or newly constructed pavements;

are easily damaged by vehicles and/or construction equipment; and

pose potential public safety issues, particularly if not removed following

construction.

Design criteria

Maximum catchment area of 0.25 hectares to each inlet; stormwater inlet

treatments should be limited to areas with a general slope of less than five

percent, and the area immediately around the inlet should be less than one

percent.

Do not completely block the stormwater system; always include a bypass

arrangement.

Devices must not be used near the edge of fill material and must not divert

water over cut or fill slopes, or away from the storm drain inlet.

Stormwater inlet protection around stormwater inlets in the low points of the

road must be set back to allow the drain to function normally during periods of

heavy rain (see Figure 7.19).

Stormwater inlet protection must not cover or block stormwater inlets, as storm

flows may be deflected around the inlet; instead use small sediment traps like

sandbags placed in the kerb and channel upslope of the inlet (see Figure 7.20).

Height of sediment control devices around stormwater inlets must be kept to

less than 300 millimetres so that runoff does not cause local flooding and/or is

not inadvertently directed into nearby catchments.



Appendix F

An earthen bund placed immediately downslope of the device may hold ponded

water around the inlet and prevent it from bypassing the drain.

Figure 7.19 Typ ical concret e b lock and gravel st o rm d rain in let p ro t ect ion at

road low p o in t s ( So urce Inst it u t ion o f Engineers, Aust ralia, 1996)



Appendix F

Figure 7.20 Typical sandbag storm drain inlet protection for stormwater inlets (Source

Institution of Engineers, Australia, 1996)

Figure 7.21 Typical excavated catchpit inlet protection (Source Institution of Engineers,

Australia, 1996)



Appendix F

Construction specifications

Construction methodology and detail will vary according to the type of inlet

protection measures proposed in the erosion and sediment control plan.

Always ensure an emergency spillway or bypass facility is included on all

devices.

Ensure the device will not cause water to bypass the storm drain system and/or

does not divert water away from its intended flow path.

Ensure the location and/or operation of the device will not cause a public safety

issue.

Keep all stockpiles or loose sediments away from roadside water tables.

There are an increasing number o f p rop r iet ary p rod uct s now availab le t h at

can und er t ake t h is f un ct ion .

Performance inspection and maintenance

Inspect daily and during and after each rainfall event and look

for blockage of the drain inlet by sediments, debris or sediment control

materials that may have been damaged during the storm event;

check for leaks in the facility which may affect its performance;

check to see that the control device has not inadvertently directed water away

from the drain and/or has not caused localised flooding; augment or modify as

required;

clean up all accumulated sediments immediately;

repair, augment and/or modify control devices as required; and

ensure all above-slope stockpiles or loose sediment is away from the roadside

water table.

Decommissioning

Decommissioning and removal procedures will vary according to the type of

inlet protection measures proposed in the erosion and sediment control plan.

Remove all accumulated sediments and dispose of them appropriately.

Remove control measure and reuse or recycle materials wherever possible.

Stabilise any areas disturbed as part of the removal process.

Useful tips



Appendix F

Stormwater drain inlet

protection measures

must not cover or block

inlets on-grade; use

small sediment traps

placed in the kerb and

channel upslope of the

inlet.

Stormwater and

sediments will pond on

footpaths, arriageways or

newly constructed

avements unless

provision is made to

bypass flows at a suitable

height.

Stormwater inlet

protection around inlets

at road low points must

be set back to allow the

drain to function

normally during periods

of heavy rain.

Additional support

should be provided to

ensure gravel-filled

sausage is not pushed

into the inlet by the force

of the water.

Height of sediment

control devices around

catchpit inlets must be

kept to less than 300mm

so that runoff does not

cause local flooding

and/or is not

inadvertently directed

into adjacent catchments.

Re-use or recycle

material found around

the site wherever

possible.



Appendix F

Attachment 5: Decanting earth bund

Extract from Erosion and sediment control guidelines for the Wellington Region; 2006.


5.6 Decanting Earth Bund

a. Definition

A temporary berm or ridge of compacted earth constructed to create impoundment

areas where ponding of runoff can occur and suspended material can settle before

runoff is discharged (see Figure 23).

b. Purpose

Used to intercept sediment-laden runoff and reduce the amount of sediment leaving

the site by detaining sediment-laden runoff.

c. Application

Earth bunds can be constructed across disturbed areas and around construction sites

and subdivisions. Keep them in place until the disturbed areas are permanently

stabilised or adequately replaced. Earth bunds are particularly useful for controlling

runoff after topsoiling and grassing before vegetation becomes established. Where

works are occurring within the berm area, compact the topsoil over the berm area as a

bund adjacent and parallel to the berm. This will act as an impoundment area and

controlled outfall while also keeping overland flow away from the construction area.

d. Design

Earth bunds require a constructed outlet structure and spillway as specified for

sediment retention ponds (see Section 5.1). Alternatively, construct an outlet of

perforated pipe connected to a non-perforated pipe that passes through the

earth bund and either discharges to a gutter or directly to a stormwater inlet.

The section of pipe within the impoundment area should be supported by

means of a rigid post, allowing filtration to occur.

Make sure the top opening of the perforated pipe is 150mm lower than the

stabilised spillway.

The section of pipe leading through the earth bund and continuing downslope

below the earth bund is non-perforated.

The maximum contributing catchment should not exceed 0.3 ha.

Position the decant inlet to provide 5% live storage volume with a minimum

distance of 5m of flat ground (or under vertical) from the outlet. Otherwise

raise the outlet so the dead storage level extends out at least this far.

e. Maintenance

After each rainfall event check the level of accumulated sediment which may cause

overtopping of the bund. If scouring is evident (after heavy rain), armour discharge

points to prevent bund collapse.



Appendix F

Attachment 6: Settlement tanks

A common practice in the construction of foundations is to dewater the foundation to

make construction easier. The water from foundation construction activities may have

significant sediment loading which is not suitable for the discharge directly to

stormwater without treatment.

An effective treatment method is to pump this water into a settling tank and allow

gravity to settle the sediment out prior to discharge to stormwater. In some instances

gravity separation is sufficient to reach a suitable discharge standard. Where this

occurs chemical flocculation can be used settle out the suspended sediment. A number

of flocculation chemicals are readily available and if applied correctly have no adverse

effects on the Environment.

Photos 1 and 2 below show the settling tank used for the construction of the Paramata

Duplicate Bridge on State Highway 1. The water and sediment from the casing to form

the piles were pumped into the sediment tank. The black arrow in photo 1 shows how

the incoming sediment is discharged intothe bottom of the tank. The clean water

decanted from the top of the tank and is discharged out of the shown by the blue

arrow. In this instance the discharged was into Porirua Harbour.

Photo 1: Interior of settling tank



Appendix F

Photo 2 shows the size of the tank which is approximately 20m3. The tanks are

emptied on a regular basis. Usually the tanks are emptied when 20% of storage is

taken up with deposited sediment.

Photo 2: Exterior of settling tank



Appendix F

Attachment 7: Geotextile Dewatering Tube

A common practice in the construction of foundations is to dewater the foundation to

make construction easier. The water from foundation construction activities may have

significant sediment loading which is not suitable for the discharge directly to

stormwater without treatment.

An effective treatment method is to pump this water into a geotextile dewatering tube.

The geotextile dewatering tube allows for the slow release of water free of sediment

which is retained within the tube.

Following the release of the majority of the water, the tubes can be reused in the same

location for further dewatering of adjacent excavations / piles.

On completion of dewatering works in a certain area, the tubes are left in place to

allow the final consolidation of sediment as the remaining water seeps or evaporates

from the tubes. The tubes and sediment are then removed for disposal in an

appropriate landfill.

Photo 3 below shows a series of geotextile dewatering tubes being used to dewater a

wastewater pond.

Photo 3: Geotextile Dewatering Tube



Appendix F

Attachment 8: Sediment Control – Pile Construction Dewatering

NEW STORMWATER CULVERT FROM

TUNNEL TO CAMBRIDGE TERRACE

NEW MANHOLE

S1

S2

S3 S4

S

5

EXISTING SUMP

EXISTING

SUMP

E

X

IS

T

IN

G

K

&

C

N

E

W

K

&

C

BUCKLE STREET

CA

MB

RID

GE

T

ER

RA

CE

KE

NT

T

ER

RA

CE

N

O

R

T

H

FOR REPORT

SC.01

SEDIMENTATION CONTROLPILE CONSTRUCTION DEWATERINGSHEET 1 of 2

BASIN BRIDGE PROJECT

R0

LEGEND

ROAD SUMP

SITE ENTRY/EXIT

SEDIMENT RETENTION TANK

CHAINLINK FENCE - SITE BOUNDARY

CONCRETE BARRIER

BUILDING WALL

DISCHARGE FLOW

PILE GROUP ARRANGEMENT

EXCAVATION AROUND PILE

NOTES

1. A GEOTEXTILE DEWATERING TUBE IS AN ALTERNATIVE SYSTEM TO THE

SETTLEMENT TANK. IF THE DEWATERING TUBE IS USED IN PLACE OF THE

SETTLEMENT TANK, THE TUBE WILL BE PROTECTED BY ONE OF THE

FOLLOWING MEASURES:

- EARTH BUND, APPROX 500mm HIGH

- PLACED IN 500mm DEEP DEPRESSION BELOW EXISTING GROUND LINE

- FILTER SOCK

- SILT FENCE

2. CONSTRUCTION AREAS TO BE STABILISED IN ACCORDANCE WITH GWRC

EROSION AND SEDIMENT CONTROL GUIDELINES FOR THE REGION.

3. SILT FENCES TO BE PLACED DOWNHILL OF CONSTRUCTION AREAS TO

CATCH STORMWATER RUN-OFF.

SEQUENCE OF WORKS

STAGE 1 - PILING FOR S1, S2 & S4.

STAGE 2 - PILING FOR S8.

STAGE 3 - PILING FOR S3, S5, S6 & S7.

0

SCALE. 1:500 @ A3

5 10 15 20 25 30

S

5

S

6

S

7

S

8

NEW SUMP (PART OF

NEW ROAD ALIGNMENT)

EXISTING SUMP

ELLICE STREET

HA

NIA

S

TR

EE

T

BR

OU

GH

AM

S

TR

EE

T

PATERSON STREET

DU

FF

ER

IN

S

TR

EE

T

N

O

R

T

H

FOR REPORT

SC.02

SEDIMENTATION CONTROLPILE CONSTRUCTION DEWATERINGSHEET 2 of 2

BASIN BRIDGE PROJECT

R0

LEGEND

ROAD SUMP

SITE ENTRY/EXIT

SEDIMENT RETENTION TANK

CHAINLINK FENCE - SITE BOUNDARY

CONCRETE BARRIER

BUILDING WALL

DISCHARGE FLOW

PILE GROUP ARRANGEMENT

EXCAVATION AROUND PILE

NOTES

1. A GEOTEXTILE DEWATERING TUBE IS AN ALTERNATIVE SYSTEM TO THE

SETTLEMENT TANK. IF THE DEWATERING TUBE IS USED IN PLACE OF THE

SETTLEMENT TANK, THE TUBE WILL BE PROTECTED BY ONE OF THE

FOLLOWING MEASURES:

- EARTH BUND, APPROX 500mm HIGH

- PLACED IN 500mm DEEP DEPRESSION BELOW EXISTING GROUND LINE

- FILTER SOCK

- SILT FENCE

2. CONSTRUCTION AREAS TO BE STABILISED IN ACCORDANCE WITH GWRC

EROSION AND SEDIMENT CONTROL GUIDELINES FOR THE REGION.

3. SILT FENCES TO BE PLACED DOWNHILL OF CONSTRUCTION AREAS TO

CATCH STORMWATER RUN-OFF.

SEQUENCE OF WORKS

STAGE 1 - PILING FOR S1, S2 & S4.

STAGE 2 - PILING FOR S8.

STAGE 3 - PILING FOR S3, S5, S6 & S7.

0

SCALE. 1:500 @ A3

5 10 15 20 25 30

Documents

Appendix F: Sediment Control Measures - NZ Transport Agency