Normanby Road Early Works Erosion and Sediment Control Plan
CRL-MTE-RME-LKA-PLN-800010 Revision: 001 Date: 21 February 20 / 21 Huitanguru 20
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Erosion and Sediment Control Plan
Erosion and Sediment Control Plan CRL-MTE-RME-LKA-PLN-800010 This document is uncontrolled when printed. This document should be printed in colour
Revision Status Revision
Date
Version details
Prepared By
Approved By
Rev A00
25/11/19
Mana Whenua / CLG Review
Troy Brockbank
Peter Roan
Rev A01
28/11/19
Auckland Council Review
Troy Brockbank
Peter Roan
Rev 000
17/12/19
Final for submission
Troy Brockbank
Peter Roan
Rev 001
21/02/20
Final
Troy Brockbank
Peter Roan
Approval Status Name/Title
Signature
Date
Prepared by:
Troy Brockbank Kaitohutohu Matua Taiao
17/12/2019
Reviewed by:
Maree Drury Consenting Lead C5
17/12/2019
Approved by:
Peter Roan Consenting Lead – Link Alliance
17/12/2019
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Table of contents 1. Introduction ............................................................................................. 5 1.1
Overview of CRL works in Mt Eden ................................................................................ 5
1.2
Purpose of the ESCP ...................................................................................................... 6
1.3
Relevant Conditions ...................................................................................................... 6
1.4
ESCP Review and updates ............................................................................................ 10
2. Normanby Road Early Works ................................................................. 11 2.1
Overview of Works ...................................................................................................... 11
2.2
Topography and Drainage ........................................................................................... 11
2.3
Construction Methodology .......................................................................................... 14
2.4
Earthworks ................................................................................................................. 14
3. Erosion and Sediment Control and Management ................................... 18 3.1
Key Principles .............................................................................................................. 18
3.2
Erosion and Sediment Control Measures ...................................................................... 18
3.2.1.
General ESC Measures .................................................................................................. 18
3.2.2.
Asphalt Works and Concrete Pumping / Pouring ......................................................... 19
3.2.3.
Erosion and Sediment Source Control .......................................................................... 20
3.2.5.
Area A: 14-22 Boston Road, 11 Water Street and 28 Mt Eden Road............................ 21
3.2.6.
Area B: 32 Normanby Road........................................................................................... 21
3.2.7.
Area C: 8-10 Boston Road ............................................................................................. 22
3.2.8.
Area D: Normanby Road, Boston Road and Water Street Corridors ............................ 22
3.3
Monitoring During Construction .................................................................................. 22
3.4
Heavy Rainfall Response & Contingency Measures ....................................................... 23
3.5
Other Considerations .................................................................................................. 23
3.5.1.
Contamination .............................................................................................................. 23
3.5.2.
Dust Control .................................................................................................................. 24
3.6
Site Reinstatement ...................................................................................................... 24
4. Roles and Responsibilities, Training and Complaint Response ................ 25 4.1
Roles and Responsibilities ........................................................................................... 25
4.2
Training ...................................................................................................................... 25
4.3
Complaints .................................................................................................................. 25
Appendix A: Record of CLG and Auckland Council Comments ...................... 26 Page 3
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Erosion and Sediment Control Plan
Appendix B: ESCP Drawing ........................................................................... 27
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1.
Introduction
The City Rail Link (CRL) project comprises the construction, operation and maintenance of a 3.4 km underground passenger railway, running between Britomart Station and the North Auckland Rail Line (NAL) in the vicinity of Mt Eden Station. The CRL also involves the construction of two new underground stations at Aotea and Karangahape and a redeveloped Mt Eden Station (refer to Figure 1-1). The design and construction of the CRL infrastructure between Aotea and Mt Eden Stations is being delivered by the Link Alliance. This Erosion and Sediment Control Plan (ESCP) has been prepared in relation to early works along and in the vicinity of Normanby Road, hereafter referred as the ‘Normanby Road early works’.
Figure 1-1: CRL Route and Location
1.1 Overview of CRL works in Mt Eden The CRL works in the Mt Eden area involve the construction of the southern section of the tunnel structures and the tie-in to the existing NAL, including the construction of the redeveloped Mt Eden Station. The Mt Eden Active Construction Zone (ACZ) and Construction Support Areas (CSA) for the NAL Mt Eden section are generally located between State Highway 1 (SH1) to the east and Dominion Road to the west. The works in this area include: • • • • • Page 5
Construction of an underground grade separation structure near Mt Eden Station; A new Mt Eden Station building incorporating passenger linkages; Modifications to the existing Mt Eden Station platforms; Road over rail bridges at Mt Eden Road, Normanby Road and Ruru Street with sections of road realignment; Grade separation structures and the east- and west-facing connections for the existing and new rail lines to pass-over and connect with each other;
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Erosion and Sediment Control Plan • •
Pedestrian and cyclist bridge structures at Fenton Street and Porters Avenue; and New road linkages within the reinstated area post-construction.
Given the nature and scale of CRL works in Mt Eden, construction will be undertaken in a staged manner. This ESCP only relates to one component of the CRL Mt Eden works, the Normanby Road early works, as described in Section 2 below.
1.2
Purpose of the ESCP
This ESCP has been prepared to identify measures that will be implemented to mitigate and manage the potential adverse effects on the receiving environment from any erosion and sediment generation during the Normanby Road early works. This ESCP addresses the matters specified in Conditions 53-58, 65-72 and 167-168 of the regional land use consent R/LUC/2016/1890 and discharge permit R/REG/20161898. This ESCP forms part of the Construction Environmental Management Plan (CEMP) for the early works (refer to designation Conditions 21.1 (b) and (c) and resource consent Condition 35) and should be read in conjunction with the CEMP and other relevant early works Delivery Work Plans (DWP) and Management Plans (MP). The ESCP has been developed in consultation with the Maungawhau (Mt Eden) Community and Business Liaison Group (CLG) (as per resource consent Condition 19). Comments received from the CLG have been (where applicable and appropriate) incorporated in the ESCP, with an explanation provided where any comments have not been incorporated. A record of the consultation outcomes is provided in Appendix A of this ESCP.
1.3
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Relevant Conditions
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Erosion and Sediment Control Plan Table 1-1 identifies the resource consent conditions relevant to this ESCP and where they are addressed in the document.
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Erosion and Sediment Control Plan Table 1-1 Relevant ESCP conditions and location in the Plan
Condition No.
Condition
Relevant ESCP section
Land use consent R/LUC/2016/1890 conditions 53
At least 20 working days prior to the commencement of construction within a Construction Support Area (CSA) or ACZ, the Consent Holder shall submit to the Council (Team Leader Central Monitoring) for certification an ESCP which provides for the management of all bulk earthworks to minimise any discharge of debris, soil, sediment or sediment-laden water beyond the site to either land and/ or stormwater drainage systems.
This ESCP
54
The Consent Holder shall request the Council's (Team Leader Central Monitoring) determination as to whether the ESCP can be certified, in writing, within 10 working days of receipt of the ESCP. No construction activity shall commence until certification from Council is provided.
Noted
55
An ESCP shall include, but is not be limited to, the following matters: • identification of construction zones and construction support areas;
2.1, 2.3, 2.4
• specific erosion and sediment control works for each Active Construction Zone (location, dimensions, capacity supporting calculations and design drawings), which should be in line with Industry Best Practice that will meet or exceed the performance of measures detailed in TP90;
3
• catchment boundaries;
2.2
• the timing and duration of construction and operation of control works (in relation to the staging and sequencing of earthworks);
2.4 and CEMP
• details relating to the management of exposed areas;
3.2.3
• reference to the Flocculent Treatment Management Plan and confirmation of erosion and sediment control measures necessary to give effect to that plan;
Not required for early works
• reference to the Contaminated Soils Management Plan and confirmation of erosion and sediment control measures necessary to give effect to that plan; and
3.2.2 and 3.5.1
• monitoring and maintenance requirements, including information on complaint investigation and response procedures, training, and roles and responsibilities.
3.3, 3.4, 4 and CEMP
56
Any change to an ESCP shall be submitted to the Council (Team Leader Central Monitoring) for certification.
1.5
57
The Consent Holder shall request the Council's (Team Leader Central Monitoring) written determination as to whether the proposed change can be certified, to be provided within 10 working days of submission of the change. No activity reliant upon a change to the ESCP can be undertaken until the change has been certified.
Noted
58
The Consent Holder shall comply with the ESCP for the duration of the earthworks associated with the Project.
Noted
65
Prior to the commencement of bulk earthworks, a certificate signed by a Senior Qualified Person shall be submitted to the Council (Team Leader
Noted
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Erosion and Sediment Control Plan
Condition No.
Condition
Relevant ESCP section
Central Monitoring) to certify that the erosion and sediment controls (including diversion bunds, silt fences and sumps) have been constructed in accordance with the certified ESCP(s) as required by Condition 53 of this consent. 66
The certification from the Senior Qualified Person for these measures shall be supplied to the Council (Team Leader Central Monitoring) immediately upon completion of construction of those measures. Information supplied, if applicable, shall include:
Noted
• The contributing catchment area; • The shape of structure (dimensions of structure); • The position of inlets/outlets; and • The stabilisation of the structure. 67
The Consent Holder shall ensure that there shall be no deposition of earth, mud, dirt or other debris on any road or footpath resulting from bulk earthworks on the subject site. In the event that such deposition does occur, it shall immediately be removed. In no instance, shall roads or footpaths be washed down with water without appropriate erosion and sediment control measures in place to prevent contamination of the stormwater drainage system, watercourses or receiving waters.
3.2
68
The operational effectiveness and efficiency of all erosion and sediment control measures specifically required as a condition of resource consent, including the certified ESCP referred to in Condition 53, shall be maintained throughout the duration of earthworks, or until the Project site is permanently stabilised against erosion.
3.3, 3.4, 3.5 and 3.6
69
The site shall be progressively stabilised against erosion at all stages of earthworks activity and shall be sequenced to minimise the discharge of contaminants to groundwater or surface water.
3.1 and 3.2
70
The Consent Holder shall ensure that the erosion and sediment control measures are constructed and maintained in accordance with TP90, except where a higher standard is detailed in an ESCP/FTMP, in which case the higher standard shall apply.
3
71
Sediment control measures shall be inspected on a weekly basis and after a significant storm event to ensure effective operation.
3.3
72
The Consent Holder shall ensure that all material removed from or delivered to the Project site shall be covered during transportation.
3.2.3
Discharge permit R/REG/2016/1898 167
In the event that any CSA requires an increase in area, the following information shall be provided to the Team Leader – Central Monitoring whose certification shall be requested prior to implementation:
Noted
a. Plans and drawings outlining the details of the modifications; and b. Supporting information that confirms how the proposal does not affect the capacity or performance of the existing structural and procedural controls. 168
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The Consent Holder shall ensure that the following structural controls are constructed for the following catchment areas and design standards and they are completed prior to discharges commencing from the site:
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3.2.4
Erosion and Sediment Control Plan
Condition No.
Condition Works/ Controls
Device Catchment Area
Design Requirements
2 x Settlement Tanks located on CSA 4
Activity area of grout plant (400m2), and segment storage yard (2660m2) on CSA 4 On all catch pits within CSA areas
Settlement Tanks sizing to be based on 2% of the contributing catchment
Inlet protection measures
2 x Settlement Tanks located in CSA 1, CSA 2, CSA 3, CSA 4 and CSA 5 Bunding of Environmentally Hazardous Substances 169
Relevant ESCP section
All Active Construction Zone (ACZ)
Design in accordance with Auckland Council Best Management Practice: Catch pit Protection Area (AC 2015). Settlement Tank sizing to be based on 2% of the contributing catchment
As required
110% largest container
In the event that any minor modifications to the structural system are required, the following information shall be provided to the Team Leader – Central Monitoring whose certification shall be requested prior to implementation:
Noted
a. Plans and drawings outlining the details of the modifications; and b. Supporting information that confirms how the proposal does not affect the capacity or performance of stormwater management system.
1.4
ESCP Review and updates
This ESCP is a live document that will be reviewed and updated as a result of a material change to the Normanby Road early works, or to address unforeseen adverse erosion and sediment runoff effects arising from construction, or unresolved complaints. Any material changes to this ESCP must be certified by Auckland Council prior to any on-site activity reliant upon the change commencing. Refer to Section 6.7 of the CEMP for further detail on the review and updating process.
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2.
Normanby Road Early Works
2.1
Overview of Works
The Normanby Road early works involve demolition of the building at 11 Water Street, establishment of a Construction Support Area, construction of a temporary pedestrian bridge across the NAL and two retaining walls, and diversion of temporary and permanent utilities (such as water, wastewater, stormwater, gas, electricity and communications) along and in the vicinity of Normanby Road. The early works are required in advance of the main construction works to provide adequate clearance between the CRL works and network utilities to enable construction of retaining walls, the Normanby Road grade separation bridge and the realigned Normanby Road / Boston Road / Nugent Street roundabout. The Normanby Road early works are planned to extend over eight months, between February 2020 and September 2020. Figure 2.1 shows the area of these works.
Figure 2-1: Extent of the Normanby Road early works area
Refer to the CEMP for a detailed description of the works.
2.2
Topography and Drainage
The Normanby Road early works area encompasses 7 stormwater sub-catchments. The catchments and their boundaries are shown on Figure 2-2. All drainage flows to Motions Creek via the existing and future stormwater system (Figure 2-3). Page 11
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Erosion and Sediment Control Plan The topography of the Normanby Rd early works area ranges in slope from 0.2% to 20%. The topography of the area will be altered with the lifting of Normanby Road for the grade separation of the road from the rail corridor as part of the subsequent main construction works.
Figure 2-2: Normanby Rd Early Works Stormwater Sub-Catchments
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Erosion and Sediment Control Plan
Figure 2-3: Motions Creek Catchment (Normanby Rd Early Works stormwater sub-catchments within blue box)
A large portion of Normanby Road is subject to the 1% Annual Exceedance Probability (AEP) floodplain and hence is a flood sensitive area. Overland flow paths (OLFPs) and flood sensitive areas in the Normanby Road early works area are shown in Figure 2-4 below.
Figure 2-4: Flood plains and OLFPs within the Normanby Road early works area
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Erosion and Sediment Control Plan The OLFPs in this area will be altered due to the change of alignment of Normanby Road with construction of the permanent road over rail bridge and grade separation. The impact of that change and how it will be managed during main works construction does not form part of this early works ESCP.
2.3
Construction Methodology
The Normanby Road early works will be divided into stages as described in the CEMP and the Construction Staging Plans in Appendix B of the CEMP. The construction sequence is summarised in Table 2.1 below.
2.4
Earthworks
Earthworks associated with the Normanby Road early works will largely comprise: •
excavation associated with network utility diversions (involving open trenching using excavators and hydro excavation trucks and directional drilling); contouring to establish Construction Support Area (CSA); and excavation associated with the construction of one retaining wall and car park regrading at 32 Normanby Road.
• •
The approximate earthworks areas and volumes required for the early works by construction stage are outlined in Table 2.1 below. Table 2.1 Construction Sequencing, Approximate Earthworks Areas and Volumes
Stage
Sub-Stages
Construction sequence of works
Approx. earthworks area (m²)
Approx. earthworks volumes (mᶟ)
Stage 0
Demolition of the building at 11 Water Street.
1. Dismentle the roof, walls and base slab. 2. Minor contouring.
100
50
1. Clear site of weeds, trees, debris. 2. Place layer of clean aggregate. 3. Set up barriers, fencing, signs.
100
125
1. Remove seal. 2. Prepare foundation. 3. Build wall.
100
10
1. Cut and shred trees. 2. Demolish Fence.
200
150
Stage 1 1.1 – (Mar – • Establishment of CSA and Apr alternative car park for 32 2020) Normanby Road within the CSA. • Construction of one retaining wall at 32 Normanby Road. • Installation of permanent south sewer line along the south driveway of 22-24 Normanby Road. 1.2 – • Construction of one retaining wall at 32 Normanby Road. • Installation of south sewer line along Normanby Road. 1.3 –
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Erosion and Sediment Control Plan
Stage
Sub-Stages
Construction sequence of works
•
3. Dig out roots. 4. Place clean aggregate working surface.
•
Stage 2 (Apr – May 2020)
Demolition of northern boundary fence, kerb and tree removal at 32 Normanby Road. Excavation and installation of south sewer line along Normanby Road.
Approx. earthworks area (m²)
Approx. earthworks volumes (mᶟ)
1.4 – • Installation of permanent stormwater line across Normanby Road.
1. Cut seal. 2. Excavate trench. 3. Install pipes and Manholes. 4. Backfill and compact trench. 5. Reinstate road and footpaths.
250
500
1.5 – • Installation of south sewer manhole and tie in to existing sewer line along Normanby Road.
1. Cut seal. 2. Excavate trench. 3. Install pipes and Manholes. 4. Backfill and compact trench. 5. Reinstate road and footpaths.
20
40
1.6 – • Installation of permanent stormwater line across Normanby Road.
1. Cut seal. 2. Excavate trench. 3. Install pipes and Manholes. 4. Backfill and compact trench. 5. Reinstate road and footpaths.
40
130
1.7 – • Installation of permanent stormwater line and catch pits at 32 Normanby Road. • Installation of private stormwater connections at 32 Normanby Road.
1. Cut seal. 2. Excavate trench. 3. Install pipes and Manholes. 4. Backfill and compact trench.
140
300
1.8 – • Regrade car park area at 32 Normanby Road in stages.
1. Strip seal. 2. Fill aggregate in layers and compact.
1200
0
1. Level aggregate platform. 2. Compact.
80
180
20
120
2.1 – • Construction of piling platform and piling for the temporary bridge at 32 Normanby Road. • Installation of permanent north sewer line across Normanby Road.
1. Deliver piling rig. 2. Drill piles. 3. Concrete piles. 4. Remove piling rig.
1. Excavate trench. 2. Install pipes and Manholes. 3. Backfill and compact trench. 2.2 – Page 15
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1. Construct formwork.
Erosion and Sediment Control Plan
Stage
Sub-Stages
Construction sequence of works
•
2. Tie steel. 3. Pour concrete. 4. remove formwork.
•
Construction of pile cap, removal of piling platform and installation of permanent stormwater line at 32 Normanby Road. Construction of piling platform and piling for the temporary bridge at 14-22 Boston Road.
2.3 – • Construction of pile cap and removal of piling platform at 14-22 Boston Road. • Reinstatement of car park surface and line marking at 32 Normanby Road. 2.4 – • Removal of temporary car park at 14-22 Boston Road. • Installation of permanent north sewer line across 14-22 Boston Road, 11 Water Street 8-10 Boston Road and the road reserve of Water Street. Stage 3 3.1 – (Apr – • Construction of a retaining wall Jul at the south-western corner of 2020) the Normanby Road / Boston Road / Nugent Street roundabout. • Construction of temporary bridge foundations at 14-22 Boston Road and 32 Normanby Road. 3.2 – • Installation of span columns and span truss across the NAL rail corridor. • Installation of temporary utilities on span columns. Stage 4 4.1 – (Aug – • Installation of temporary gas, Sept water, power and 2020) communication lines from the Page 16
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Approx. earthworks area (m²)
Approx. earthworks volumes (mᶟ)
140
300
1. Excavate trench. 2. Install pipes and Manholes. 3. Backfill and compact trench.
350
500
1. Clear area. 2. Prepare foundation. 3. Build wall. 4. Backfill behind wall. 5. Compact Backfill.
150
250
1. Set up for Night works. Stop Trains. 2. Lift columns and secure in place. 3. Lift span and secure in place. 4. lift utilities and secure in place.
0
0
1. Excavate Trench. 2. Install Utilities. 3. Connect Utilities. 4. Backfill and Compact Trench.
80
150
1. Deliver piling rig. 2. Drill piles. 3. Concrete piles. 4. Remove piling rig. 1. Construct formwork. 2. Tie steel. 3. Pour concrete. 4. Remove formwork. 1. Level Aggregate. 2. Compact. 3. Reseal. 4. Line mark carpark.
Erosion and Sediment Control Plan
Stage
Sub-Stages
•
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temporary bridge to existing lines. Installation of screens on the temporary bridge.
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Construction sequence of works
5. Reinstate Road and Footpath. 6. Lift screens into place. 7. Bolt screens.
Approx. earthworks area (m²)
Approx. earthworks volumes (mᶟ)
Erosion and Sediment Control Plan
3.
Erosion and Sediment Control and Management
Erosion and sediment control measures will be designed, installed and maintained in accordance with Auckland Council “Erosion and Sediment Control Guide for Land Disturbing Activities in the Auckland Region”, Guideline Document 005 (GD05). It is noted that GD05 has superseded Auckland Council Technical Publication 90 (TP90) “Erosion and sediment control guidelines for land disturbing activities in the Auckland Region”, which is referred to in the resource consent conditions.
3.1
Key Principles
Key erosion and sediment control principles applicable to the early works are as follows: •
Selection of construction methodologies and staging of construction to limit the duration and area of earthworks exposed to erosion at any given time. Minimise the total area of disturbance by keeping the area of earthworks to a minimum and progressive stabilisation of exposed areas. Avoidance of OLFPs where practicable. Protection and stabilisation of steep slopes through the use of clean water diversion bunds (CWD), and vegetative covers. Stabilisation of exposed surface areas as soon as practicable. This may include one or more of the following measures:
• • • •
• •
• •
Application of granular material, straw mulch, hydro-seeding or grassing (either temporarily or permanently). Installation of downslope perimeter controls or diversions around and within the construction area, to detain and treat sediment laden runoff and prevent contamination of the existing stormwater system and receiving environment. Adoption of specific construction practices within the construction area to minimise sedimentation generation during trenching.
Regular inspection and maintenance of sediment control devices.
3.2
Erosion and Sediment Control Measures
3.2.1.
General ESC Measures
Erosion and sediment control measures (ESCM) will be installed prior to the start of any vegetation clearance, site set up or earthworks. The mitigation measures will remain in place until reinstatement of active working areas is complete. ESCM identified in Table 3-1 shall be implemented throughout the construction area as illustrated in the ESCP Drawing in Appendix B. All ESCMs shall be designed and maintained in accordance with GD05. Table 3-1 General Erosion and Sediment Control Measures
ESCM
Application
Catchpit/ Stormwater inlet protection
•
Page 18
•
Cover catchpit grates and inlets with geotextile to filter sediment laden runoff before discharge into the stormwater network; or Other proprietary catchpit protection systems, such as silt/filter sock, sand logs, coir logs and hay bales.
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Erosion and Sediment Control Plan ESCM
Application
Diversion channel/bund
• • • •
Filter socks
• •
Install to divert runoff from external catchments entering construction areas or for conveyance of sediment laden runoff within construction areas. Hot mix diversion bunds can be used where kerb and channels have been removed or on impervious surfaces. Diversion bunds must have sufficient capacity to carry the flow safely from a 5% AEP storm, with 300mm freeboard, in accordance with GD05. Filter socks can be used to intercept and impound runoff before it enters a catchpit or other stormwater inlet. Can be used to reduce the velocity of runoff flows within a channel, as a check dam. Contain and impound discharges from pumped stormwater or concrete wash water (as a turkey nest to promote settlement).
Sand logs/coir logs/hay bales
•
Use in carriageway to divert clean water from construction site where there is steep terrain uphill or unfavourable carriageway cross fall.
Dewatering required)
•
Dewatering devices will be used to pump out any water that collects within open trenches or excavation areas or for sediment control devices for maintenance. A minimum of 100mm water clarity is required to pump out of the works area. If this cannot be achieved, the water shall be pumped to settlement tanks or to a tanker and removed offsite.
(if
•
Settlement Tanks
• • •
Stabilised entrance surface
and
• • •
3.2.2.
Settlement tank sizing is based upon 2% of the exposed area. Water quality standards must be met before discharging to an existing stormwater inlet, whereby pH ranges are between 5.5 to 8.5 and clarity is greater than 100mm. The settlement tanks will be emptied using a vacuum truck when full, and the sediment-laden runoff is to be disposed offsite. Install at egress points for construction outside of the carriageway. Any cut or exposed surfaces within the construction area can be stabilised with aggregates. All aggregates should comply with minimum thickness of 150mm with 50-150mm washed aggregate sizing.
Asphalt Works and Concrete Pumping / Pouring
The amount of concrete and asphalt works are expected to be small scale during the Normanby Road early works. The environmental risk of concrete or asphalt works is high, and it is recommended that drainage channels are completely isolated during these works. If this is not practicable, careful placement of sandbags or bunds should be implemented. Other recommended controls are: • Delay concreting works when bad weather is forecast, if practicable. • Minimise the volume of water used on site (e.g. in dust suppression, concrete cutting) so there is less to control. • Use concrete saws that can have a vacuum attached to minimise the amount of dust produced during cutting, OR use a wet/dry vacuum, to collect all concrete or asphalt contaminated material or runoff on site. • If the above is not practical, divert all runoff to the construction pit/ trench or unsealed ground, away from OLFPs. Runoff or wash water contaminated with concrete fines / dust is highly alkaline and cannot be diluted, therefore, all captured runoff from concrete cutting and/or cement mixing must be treated or disposed off-site. Page 19
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Erosion and Sediment Control Plan • •
Wash all equipment and tools in a designated site wash out area. Do not allow concrete trucks or concrete pumpers to wash out on site unless there is a designated wash area. Use tarpaulin sheets under concrete pumps and delivery chutes to capture any spills.
•
3.2.3.
Erosion and Sediment Source Control
The erosion and sediment source controls listed in Table 3-2 have been identified as applicable to all of the early works area. Table 3-2 General source control measures applicable to the works area for elimination and/or minimisation of erosion and sediment generation
Source/Activity
Source Control Measure
General site management
• • •
• • Soil Management & Stockpiles
• • • •
• • Sediment transport due to runoff from external catchments entering the construction site
•
Open trench work
•
•
•
• Erosion due to runoff travelling over reinstated ground
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Ensure OLFPs are unobstructed and stabilised (if required), if practicable. Check the weather forecast and plan accordingly if there is to be heavy rainfall/wind; Stabilise work areas with high sediment generation potential as soon as practicable by placing geotextile and covering with clean hardfill or other approved method; Regularly sweep or remove any accumulated sediment associated with the works; Refer to the Air Quality Delivery Work Plan (AQ DWP) with regards to dusty exposed working areas to minimise wind distribution of sediments. Soil removal using hydro excavation will be disposed of at an approved offsite facility. All soil removed should be placed in covered trucks for off-site transport. Stockpiles are to be in construction areas serviced by ESCMs only. Stockpiles of fine material shall be dampened or covered to reduce the potential for windblown sediments or the generation of sediment laden runoff, refer to the AQ DWP for details. Stockpiles shall be located away from OLFPs. Hazardous construction materials (if any) shall be stored in an isolated and bunded area in accordance with the CEMP. Construct diversion bunds/channel to divert runoff from external catchments entering land disturbance sites; and Use clean water diversions (e.g. sandbags, compacted earth, bund) where there is steep terrain uphill of the works area to reduce the volume of water requiring management. Cut and Cover methodology shall be adopted. Backfill and compact trenches as soon as possible in an immediate and progressive manner; Exposed areas shall be stabilised as soon as possible and at the end of each day’s operations. This can include aggregate for carriageway and footpath areas and topsoil, seed and mulch/geotextile for landscaping and berm areas. Dewatering of trenches and/or excavations must be pumped to a retention device (settlement device) and/or removal. Do not remove ESCMs until the reinstatement of active working areas is established.
Erosion and Sediment Control Plan
3.2.5.
Area A: 14-22 Boston Road, 11 Water Street and 28 Mt Eden Road
Area A footprint (5,768m2) and ESCMs are depicted in the ESCP Drawing attached in Appendix B. This section describes the erosion and sediment control measures that will be implemented for construction work within Area A, which includes 14-22 Boston Road, 11 Water Street and partly within 28 Mt Eden Road (demolition of building at 11 Water Street, CSA establishment, alternative car park developed, south sewer line diversion, and temporary bridge foundation and piling). The proposed erosion and sediment controls that will be implemented during the works are as follows: •
Stabilised entrance is required at two existing entry/exit locations - Normanby Road and Water Street to ensure that sediment is not transported out of the construction area. Catchpit inlet protection will be required at stormwater catchpit within the work area which discharges into the existing stormwater network. Silt fence is required to be installed along the downstream boundary to capture coarse sediments carried in sheet flow and temporarily impound sediment-laden runoff, slowing down the flow rate and allowing sediment to settle out of the water. Diversion bund to divert clean water away from the construction zone to a stormwater inlet and dirty water to the two settlement tanks. Clean water and dirty water diversion (CWD and DWD) must have sufficient capacity to carry the flow safely from a 5% AEP storm. Two settlement tanks (total capacity 115m3) will be placed in the south west corner of Normanby CSA 5 to service the wheel wash for trucks and runoff within CSA. The settlement tanks will be emptied using a vacuum truck when full and the sediment-laden runoff will be disposed of at an appropriate off-site location. Two in-line settlement tanks are proposed, designed to service at minimum 2% of the contributing catchment area with tank sizing outlined in Table 3 3.
• •
•
•
Table 3-3 Settlement Tank Sizing for Normanby CSA 5
Stage Number
Settlement Tank Sediment Retention
/
Normanby CSA 5
(Sediment Retention) SR containing 2 in-line tanks (included in the water treatment area)
Contributing Area (m2) 5,768m2
Catchment
Minimum Settlement Tank Volume (m3) * 115m3
* Minimum volume for settlement retention device is calculated as 2% of the contributing catchment area.
3.2.6.
Area B: 32 Normanby Road
ESCMs for Area B are depicted in ESCP Drawing attached in Appendix B. This section describes the erosion and sediment control measures that will be implemented for construction work within Area B, being 32 Normanby Road (land adjoining NAL). Works within 32 Normanby Road comprise removal of vegetation and fence along the northern boundary, upgrade to the stormwater network to alleviate flooding, installation of private stormwater connections, construction of one 1.8m retaining wall to the south of the vehicle access, construction of the temporary bridge foundation and piling and regrading of the carpark. The proposed erosion and sediment controls for the avoidance and mitigation of the sedimentation of the area are as follows:
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Erosion and Sediment Control Plan •
Catchpit inlet protection will be required at each stormwater catchpit within the works area which discharges into the existing stormwater network.
•
Cut and cover construction methodology throughout. All disturbed area will be stabilised with mulch, gravel, geotextile or clean aggregate as appropriate at the end of each day.
3.2.7.
Area C: 8-10 Boston Road
ESCMs for Area C are depicted in ESCP Drawing attached in Appendix B. This section describes the erosion and sediment control measures that will be implemented for construction work within Area C, being 8-10 Boston Road (land adjoining NAL). Works within Area C comprise south sewer line diversion, private connections, and re-establishment of surfaces. As the Area C works are within the sealed carpark and adjacent impervious areas, the ESCMs proposed are: •
Catchpit inlet protection will be required at each stormwater catchpit within the works area which discharges into the existing stormwater network.
•
Cut and cover construction methodology throughout. All disturbed area will be stabilised with mulch, gravel, geotextile or clean aggregate as appropriate at the end of each day.
3.2.8.
Area D: Normanby Road, Boston Road and Water Street Corridors
ESCMs for Area D are depicted in ESCP Drawing attached in Appendix B. This section describes the erosion and sediment control measures that will be implemented for construction work within the road corridors, of Normanby Road, Boston Road and Water Street. Works within these road corridors comprise diversion of sewer, water, stormwater, gas, power and communication lines along Normanby road and diversion of water main connection into the footpath at Boston Road. As the Area D works are with the sealed road corridor, the ESCMs proposed are: •
Catchpit inlet protection will be required at each stormwater catch pit within the works area which discharges into the existing stormwater network.
•
Cut and cover construction methodology throughout. All disturbed area will be stabilised with mulch, gravel, geotextile or clean aggregate as appropriate at the end of each day.
3.3
Monitoring During Construction
All site-specific erosion and sediment control measures will be inspected on a weekly basis and after rainfall events by the Link Alliance. Inspection will include, but will not be limited to, the requirements outlined in Table 3-4. Table 3-4 Monitoring Requirements for ESCM
Erosion Control
and
Sediment
Catchpit / Stormwater Inlet Protection
Inspection/Maintenance Requirements
Frequency
•
Daily, before & after rainfall
•
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Check for damage, blockages and leaks – repair immediately. Remove accumulated sediment immediately.
Erosion and Sediment Control Plan Erosion Control Clean & Diversion Channels
and
Sediment
Dirty Water Bunds and
Inspection/Maintenance Requirements
Frequency
•
Check for scour and areas where a breach may or has occurred – repair immediately. Remove sediment build up deposited in the DWD channel. Check for low spots, formation of gullies or debris – repair immediately.
Weekly & after rainfall
Check quantity of aggregate and geotextile for sediment build up and deterioration – apply more aggregate as required. Check aggregate thickness and if not GD05 to specification then apply more aggregates or change as required.
Weekly & after rainfall
Check if the tank is full, then empty using vacuum truck and the sediment-laden runoff to be disposed offsite.
Weekly rainfall
• •
Stabilised Entranceway and Surface
•
•
Settlement Tanks
3.4
•
and
after
Heavy Rainfall Response & Contingency Measures
The Normanby Road early works are planned to extend over 7 months, between March 2020 and September 2020. High intensity rainfall events can occur during the summer months as well as prolonged rain events during winter months. The Link Alliance shall monitor weather forecasts, inspect all erosion and sediment control measures for adequacy, and undertake any remedial works required prior to forecasted rain events.
3.5
Other Considerations
3.5.1.
Contamination
In accordance with the Contamination Delivery Work Plan (CDWP), refer Appendix M of the CEMP, the early works area contains uncontrolled fill and the current/historical surrounding commercial/industrial land use activities present a risk of contaminated soil being encountered during land disturbance activities. Until further contaminated land investigation works are undertaken, it must be assumed that the uncontrolled fill contains elevated concentrations of contaminants. Section 4.2 of the CDWP outlines additional erosion control measures that will be implemented during all land disturbance activities, including cleaning up spillages of soil during placement in trucks as soon as practicable to avoid contaminated soil being trafficked by trucks and transported off-site. Any groundwater that is encountered during earthworks will be considered potentially contaminated until otherwise tested. Groundwater will be collected and discharged in accordance with a Trade Waste Permit or discharge to the stormwater system, where sampling has been undertaken and results show compliance with 50 times the Australian and New Zealand Environment Conservation Council (ANZECC) Guidelines for Fresh and Marine Water Quality (2000) (ANZECC, 2000).
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Erosion and Sediment Control Plan During all land disturbance activities, site staff will actively monitor active work areas for the conditions/materials specified in the CDWP. Section 6 of the CDWP outlines the measures to be implemented if suspected contaminated material is discovered.
3.5.2.
Dust Control
Land disturbance activities shall be undertaken in accordance with the AQ DWP (Appendix I of the CEMP) in order to minimise the potential for dust generation.
3.6
Site Reinstatement
Decommissioning of ESCM shall only occur once the active works areas are permanently stabilised. Due care will be taken during the removal process so as not to mobilise any sediment.
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Erosion and Sediment Control Plan
4.
Roles and Responsibilities, Training and Complaint Response 4.1 Roles and Responsibilities
The key environmental management roles during construction are outlined in the CEMP. However, all site personnel will be responsible for following the requirements of this ESCP during the Normanby Road early works.
4.2 Training All site staff will undergo general environmental awareness training and training about their responsibilities relating to this ESCP. Training requirements are described in detail in the CEMP. Specific training requirements relating to this ESCP are outlined in Table 4.1. Table 4.1: ESCP training requirements
Training requirements
Frequency
Attendance
Training on ESCP requirements and resource consent conditions.
As required and during new staff induction
All new site staff
Tool box meetings on site to include erosion and sediment control as a standard agenda item.
Weekly tool box meetings, or as required (e.g. start of new substantial activity)
All site staff
Construction, maintenance and inspections of erosion and sediment control devices
As required
Site supervisors and staff site with erosion and sediment control management responsibilities
4.3 Complaints Any complaints received during the early works shall be recorded and promptly investigated to identify and resolve the cause of the complaint in accordance with the complaints response protocol detailed in the early works Communication and Consultation Plan (Appendix X of the CEMP).
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Erosion and Sediment Control Plan
Appendix A: Record of CLG and Auckland Council Comments A1 CLG comments A CLG was held at 97 Mt Eden Rd on 25 November 2019. Erosion and Sediment control measures were explained in relation to the trenching activity and works within the construction yard. No specific concerns were raised.
A2 Auckland Council Comments The Auckland Council reviewer has found the plans to be consistent with the relevant resource consent and designation conditions.
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Erosion and Sediment Control Plan
Appendix B: ESCP Drawing
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DB
CWD
Key
CW
D
D CW
CW D
Wheel Wash
ar P e
icl eh
V
DB
CW
DB
DB
SF
DB Stabilised Construction Entrance Catchpit Protection
DB
D
CWD
Wheel Wash
DB
CW
DB
Silt Fence
DB
CW D
CWD
Diversion Bund
DB
g kin
DB 5,768.3 sq m
D
Clean water Diversion
CWD
DB
DB
Designation Boundry
Runoff Storage Tank
DB
Cut and Cover Area
SF
SF
Spoil Pile Aggregate Stock Pile Catchment Area
59.6 sq m
Concrete Wash Area
Discharge treated runoff to Stormwater inlet. Protect Manhole from untreated site runoff.
Temporary Culvert Dirty water flow Treated water
Catchment Area = 5768 m2 Tanks 2% minimum volume = 115 m3 Client :
Link Alliance has prepared this document for the sole use of the client and for a specific purpose, each as expressly stated in the document. No other party should rely on this document without the written consent of Link Alliance. Link Alliance undertakes no duty, nor accepts any responsibility, to any third party who may rely upon or use this document.
A00
P Young
10/10/19
Construction Staging P Young
Normanby Road Early Works P Young
COMPANY NUMBER : 6267870
Creator ID : CRL-EFC-CON- LKA-DRG
Erosion and Sediment Control Plan CRL
EFC
CON
LKA
DRG
800000
A00