Sample Trigger Action Plan (TAP)
Doc Ref: APP113
Folder
183
3 February 2014
DCO-DT-APP-ZZ100-10000
Application for Development Consent
Application Reference Number: WWO10001Trigger Action Plan
1
Executive Summary
This Trigger Action Plan document has been prepared to set out the mitigation that will be provided to <School XX>, in the event that construction noise levels from the adjacent Thames Tideway Tunnel, <WW> worksite, exceed certain pre-defined Trigger Action Levels which could lead to a significant adverse effect on the users of the School.
Section 2 provides a glossary to explain the technical terms which are used in the document.
Section 3 sets out the purpose of the document more fully, defining the parties and policies to which this Plan relates.
Section 4 provides a general explanation of Trigger Action Plans, a description of the receptor to which this Plan relates and the works that the Plan relates to.
Section 5 sets out the mitigation that would be provided in the event that the Trigger Action Levels are exceeded (Note: current draft presents examples).
Section 6 defines the Trigger Action Levels for the School which would trigger the installation of the mitigation described in Section 5.
Section 7 sets out the programme for each of the mitigation items described in Section 5.
Section 8 sets out corrective measures, which will be put into place in the event that Trigger Action Levels, which have not been predicted to be exceeded, are exceeded in practice.
The Appendices provide more detailed information on each of the items within the plan itself. These are intended more for a technical readership, whereas the main body of the Plan is intended specifically for the beneficiaries of the scheme.
2
Glossary of Terms
The Infrastructure Provider
- The Infrastructure Provider as defined in article 2(1) of the DCO or, with the consent of the Secretary of State, another body who implements the DCO.
The Proposed Scheme
- TBC Best Practicable
Means
- “best practicable means” as defined in the Control of Pollution Act (1974), where:
“practicable” means reasonably practicable having regard among other things to local conditions and circumstances, to the current state of technical knowledge and to the financial implications
The “means” to be employed include the design, installation, maintenance and manner and periods of operation of plant and machinery, and the design,
construction and maintenance of buildings and acoustic structures.
Section 61 Consent - A prior consent for work on a construction site given by a local authority under Section 61 of the Control of Pollution Act (1974)
Lowest Observed Adverse Effect Level
- As defined in the Noise Policy Statement for England (March 2010), i.e. the level above which adverse effects on health and quality of life can be detected.
Significant Observed Adverse Effect Level
- As defined in the Noise Policy Statement for England (March 2010), i.e. the level above which significant adverse effects on health and quality of life occur.
The Policy - The Thames Tideway Tunnel (TTT) Non Statutory Off-site Mitigation and Compensation Policy
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Purpose
3.1.1 This is a Trigger Action Plan (TAP) for <School XX> (<School X>). 3.1.2 This TAP forms part of the Thames Tideway Tunnel (TTT) Non Statutory
Off-site Mitigation and Compensation Policy (‘the Policy’) and is
enforceable under the Policy. This TAP should be read in conjunction with the Policy.
3.1.3 This TAP defines noise trigger values for the onset of a potentially significant observed adverse effect on the occupants / users within the curtilage of the school, both inside and outside space. The mitigation that will be implemented in the event that the trigger values are predicted to be exceeded by noise generated by the construction of TTT is also defined in this TAP as is the programme for its installation.
3.1.4 This TAP is agreed by TWUL and either the landlord / owner of <School X> or the Independent Compensation Panel as defined in Appendix A. 3.1.5 The works that could give rise to noise that exceeds the values set
out in this TAP shall not be started until the mitigation required by this TAP is fully in place.
4
Introduction
4.1
Trigger Action Plans
4.1.1 Thames Water Utility Ltd (TWUL)1 acknowledges that the circumstances surrounding the potential airborne noise impacts of the construction works at the <WW> Worksite will mean that <School X> is potentially
significantly affected by noise.2
1
Thames Water Utilities Ltd (TWUL). The Draft Development Consent Order (DCO) contains an ability for TWUL to transfer powers to an Infrastructure Provider (as defined in article 2(1) of the DCO) and/or, with the consent of the Secretary of State, another body.
2
4.1.2 The specific mitigation to be provided, as a minimum, on site to reduce noise and vibration at all receptors is defined in each Code of Construction Practice (CoCP) Part B.
4.1.3 The Environmental Statement (ES), as revised during the examination process, sets out the potential residual significant noise and vibration effects taking account of the mitigation in the CoCP Part B.
4.1.4 The Infrastructure Provider must deliver the works such that the residual noise and vibration effects are no worse than those reported in the ES2. 4.1.5 The Infrastructure Provider and its contractors are required by the CoCP,
Part A, to carry out the construction of the Proposed Scheme in a manner that will minimise the emission of noise and vibration as far as reasonably practicable. This may avoid or reduce the need for noise insulation, temporary re-housing or other off-site mitigation.
4.1.6 Since no further on-site mitigation is feasible at this stage of planning, this Trigger Action Plan (TAP) has been prepared for <School X> to define noise trigger values and the mitigation package that would be
implemented in the event that the trigger values were exceeded by noise generated by the Proposed Scheme. The TAP will ensure that the specific mitigation required is determined, and agreed, with all relevant consents in place such that, if required, it will be implemented quickly and be in place ahead of the works that give rise to the need for the mitigation.
4.2
Receptor
4.2.1 This is a Trigger Action Plan (TAP) for <School X>
4.2.2 The postal address for this property is: <School Address> 4.2.3 The property is a school and is owned by <Owner>.
Property use
4.2.4 Lessons at the school run from 09:00 to 15:30
4.2.5 There are also a number of after school clubs running every weekday. Typically these finish at 16:30 although some finish at 17:30. On Mondays and Fridays, there are also pre-school clubs which begin at 08:00.
Noise sensitive spaces
4.2.6 Appendix B provides site layout / floor plans. 4.2.7 Internal noise sensitive spaces in the property are:
a. New Building main hall (currently used for testing, as a gymnasium, and for assemblies and breakfast / lunchtimes), offices and reception area
b. Main Building – Ground Floor (reception classrooms)
c. Main Building – First Floor (classrooms, headteachers office and staffroom)
4.2.8 External noise sensitive spaces in the property are: a. Playground (occasionally used for teaching)
Existing noise / vibration levels
4.2.9 Monitoring of existing noise outside the property and inside the noise sensitive internal spaces as listed in paragraphs 4.2.7 and 4.2.8 was undertaken on <date>. Details of the surveys and survey results are presented in Appendix C.
Existing sound insulation and noise mitigation
4.2.10 Physical measurements were taken of the various building elements, including the glazing thicknesses. Details of the existing building fabric and sound insulation are presented in Appendix D.
4.2.11 Existing sound insulation and ventilation:
a. Based on the measurements taken on site, it is estimated that the sound insulation of the New Building is approximately 32 dB R’w when the automated windows are closed. This falls within the range of sound insulation performance that could would achieved under the Government’s Noise Insulation Regulations.
b. Based on the measurements taken on site, it is estimated that the sound insulation provided by the windows of the Main Building is approximately 20 dB R’w. For the windows this is lower than the sound insulation identified by the Noise Insulation Regulations.
4.3
TTT Works
4.3.1 This receptor is adjacent to the following TTT construction site: <WW>. 4.3.2 TTT works are scheduled to start at this site in October 2016, and are
planned to take be carried out in the following Phases:
Phase Description Scheduled start
1 Site set-up October 2016
2 CSO drop-shaft construction June 2017 3 Construction of other structures January 2018 4 Completion of works and site
restoration
September 2018
4.3.3 The TTT Environmental Statement, as revised during the DCO application examination period, reported that <School X> could be potentially
Construction activity Type of significant effect Duration of significant effect Estimated start date of significant effect
Site set-up and demolition
Noise 3 months October 2016 CSO drop-shaft
construction – D-walling
Noise 5 months June 2017
4.3.4 As required by the CoCP, the contractor is required to implement Best Practicable Means to minimise noise. The contractor’s proposals and associated noise assessment may therefore identify that off-site mitigation at this property is not required. This would be confirmed by the local authority the <Local Authority Name> as the contractor seeks prior
consent for its works under section 61 of the Control of Pollution Act 1974 (Section 61 Consent).
4.3.5 The owner and occupier of the property will be notified in writing no later than one week after the relevant local authority has given Section 61 Consent with a formal offer to provide mitigation as set out in this plan. As needed, the letter will set out when the Trigger Action Levels set in this plan are forecast to be exceeded and for how long they will be exceeded. The letter will also provide a reminder of the timescales for providing the triggered mitigation measure under this plan and the requirement for timely access to the property.
4.3.6 Further information is provided in the section 0 of this plan.
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Mitigation
5.1.1 Based upon the surveys undertaken the noise insulation packages that will be provided, should the trigger values in section 6 be exceeded, will
comprise of the following: a. New Building
i First Trigger Action Level (NB1)
It is considered impracticable to increase the performance of the current glazing. Therefore a mechanical ventilation solution would need to be provided to negate the requirement to open windows to provide sufficient ventilation and cooling.
During the works a mechanical supply ventilation strategy would be implemented in lieu of the natural ventilation if opening
windows meant that recommended internal sound level limits were exceeded. Either a new attenuated roof mounted fan to provide outside air to low level or an attenuated fan set connected to a weather louvre in place of one of the existing high level opening
windows performing the same function. This could be removed or maintained after the works.
As a further enhancement the fan set could include a DX cooling
coil to temper the air during hotter days. This may be attractive if they currently have overheating issues in the hall, as suggested by the wall fans.
ii Second Trigger Action Level (NB2)
Because it is impracticable to increase the performance of the glazing, relocation would be triggered at the second action level (detail to be agreed).
b. Main Building
i First Trigger Action Level (MB1) Glazing
There are two options for providing a first step-increase in the performance of the glazing for the main building which is in the St. Paul’s conservation area.
Option G1
The first would be to replace the existing sash windows with
double glazed units with applied mullions and transoms replicating the appearance of the original windows. Conversations with the conservation officer have indicated this would likely be acceptable providing slim double glazed units were used and the windows had timber frames.
Option G2.
The second option would be to secondary-glaze the existing windows. This would increase the sound insulation and therefore the external trigger level by a similar amount. It is understood that the preference of the school would be for secondary-glazing on condition that the system employed was easy to operate, clean and maintain, and that there was some provision for additional shelf space to make up for losing the sill space. As secondary glazing would be the preferred option for the council’s
conservation officer and likely provide the greatest acoustic benefit this option is thought the best approach.
This option is therefore recommended as it would provide the high level of acoustic protection, engagement has confirmed that it would be in principle acceptable to the school and local planning authority and it avoids some of the constraints on changing windows given that the School is in a conservation area. This option would also provide long term benefit in terms of improving noise and thermal insulation.
There are two potential options for providing ventilation and cooling, assuming that noise levels are high enough that the windows can no longer be opened:
Option V1
Part of the glazing will include a weather louvre section connected to an attenuated supply and extract fan mounted at high level within the classrooms to provide equivalent ventilation to each space. The fan will be controlled at various speeds (low in winter, higher in summer) and could even include connection to CO2 sensors to react to changing air quality. After the works the louvre section could be replaced by a vision glazing panel and the fans removed leaving a naturally ventilated solution as before. Option V2
Provide a central air handling unit at high level in the corridor of each of the three floors. From this unit, supply and extract ductwork is connected to each individual classroom space
providing ventilation. Cross talk attenuation will be required. After the works the unit could either be left in place or removed, allowing ventilation naturally through upgraded glazing. As an extra
enhancement a DX cooling coil could be provided within the AHU to provide slightly tempered air during the summer.
This is the recommended option because it would create less background noise in each individual classroom. While this option is contingent on there being enough area on each façade for louvres, the local authority’s conservation has expressed that they would look favourably on this option if it were a temporary
installation, and the louvres were coloured appropriately. ii Second Trigger Action Level (MB2)
The second action level would be to implement both the secondary and double glazing options above.
iii Third Trigger Action Level (MB3)
The third action level would involve either reprogramming the room usage within the school, or relocation (detail to be agreed). c. Playground
i First Trigger Action Level (PG1)
The first action level involves enhancing the existing school
boundary wall and ball stop fence to form a 4m high barrier which provides increased protection the playground. The barrier will also provide additional screening to the New Building and to the ground floor of the Main Building.
The ball stop fence and school gates would be clad for the duration of the works with a transparent material. [detailed design, finishes and drawings to be prepared]
ii Second Trigger Action Level (PG2)
The second action level would involve either stopping some works so that they did not exceed the levels when the outside area is used for teaching, or providing alternative outdoor teaching space <to be confirmed>.
5.1.2 Plans and drawings for the mitigation items are provided in Appendix F. 5.1.3 The following consents are required to install this insulation package.
Copies of the consents are provided at Appendix F.
Consent Required and granted?
Tenant ?
Planning permission ? Conservation area TBC Listed building N/A Building regulations ?
6
Trigger Action Levels
6.1
Noise
6.1.1 For non-residential property, property trigger values have been set based upon the current guidance for the design of new schools:
a. Building Bulletin 93 (2004). Department for Education.
6.1.2 Consistent with the Government’s noise policy (as defined in the Defra’s Noise Policy Statement for England, 2010) and emerging National Planning Practice Guidance, the design criteria set out in the above standards and specifications can be considered lowest observed adverse effect levels.
6.1.3 The lowest observed adverse effect levels (LOAEL) have been scaled to
significant observed adverse effect levels (SOAEL) by taking the higher
of (a) the existing ambient noise level + 3 dB(A), and (b) the upper limit from the relevant guidance plus 5 dB(A).
6.1.4 Action under this plan is triggered if the predicted or measured
construction noise level exceeds the outdoor trigger level at the property during at least ten days out of any period of fifteen consecutive days or alternatively during 40 days in any 6 month period.
The contractor will use the permanent monitoring location defined on plan XXX. All noise predictions will also be made to this point as part of s.61 consent applications. Appendix X presents how noise levels at this prediction / monitoring location should be adjusted to the worst effected window on the New and Main Buildings
6.1.5 The mitigation will be provided at against increasing trigger values is defined as follows <example data>:
Noise trigger level (dB LAeq,1hr) Play Ground New Building Main Building 60 PG1 65 MB1 70 NB1 75 MB2 80 NB2 85 MB3 .
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Programme
7.1.1 Based on the surveys undertaken, the programme for providing the noise insulation and ventilation triggered under this plan is set out below. The starting date is the date on which the local authority provides Section 61 Consent for the works.
7.1.2 The installation will need to take place at a time when it will not
detrimentally affect the operation of the school, i.e. during school holidays. Based on the likely extent of any such works it is likely that this will need to take place during school holidays.
a. Issue formal offer [day of consent] b. Acceptance of the offer [2 weeks] c. Arrange access [1 week]
d. Installation of mitigation [<define>]
8
Corrective Action
8.1.1 If the Section 61 consent approvals confirm that mitigation under this plan is not triggered but during the works measured construction noise levels exceed a trigger value in this plan then either
a. The relevant construction activity will be stopped until the mitigation has been implemented, or
b. The relevant construction activity will be modified to keep the level of exposure below the trigger value until the mitigation has been
implemented.
8.1.2 The course of action will be agreed with the local authority as a variation to the Section 61 Consent as defined by the CoCP.
8.1.3
The beneficiary of this plan will be informed of the exceedence and the course of action agreed with the local authority as soon as practicable [define time limit – 1 day?].Appendices
Appendix A: Agreement and approval of this TAP Appendix B: Site layout / floor plans etc
Appendix C: Survey of existing noise / vibration levels
Appendix D: Sound insulation of existing building fabric, windows and penetrations
Appendix E: Plans and drawings for noise insulation or other mitigation Appendix F: Consents and permissions
C. Existing Noise and Vibration Levels
Existing noise sources that affect this property are trains running through the nearby railway station, road traffic on local roads and the westerly arrivals flightpath for Heathrow Airport.
Building Bulleting 93 is the recognised national guidance document for the design of new-build schools. Although this is an existing school, the document provides a useful means of benchmarking the existing spaces.
a. Internal
Existing noise levels in the internal noise sensitive spaces in the property are:
New Building
Noise levels measurements were made in the new building with the ventilation fans operating. The ambient noise level measured in the new building main hall was 46 dB(A). This is significantly above the recommended upper limits for gymnasiums, assembly halls and quiet study areas from Building Bulleting 93, which are 40 dB(A), 35 dB(A) and 35 dB(A), respectively.
The noise level measured in the office was 37 dB(A). This is slightly below the recommended upper limit from Building Bulletin 93 for offices, 40 dB(A).
Main Building
Ground FloorThe ambient noise level measured in a ground floor classroom facing the site was 36 dB(A). This is marginally above the recommended upper limit of 35 dB(A) for nursery and primary school classrooms from Building Bulletin 93.
First Floor
The ambient noise level measured in a first floor classroom facing the site was
36 dB(A). This is marginally above the recommended upper limit of 35 dB(A)
for nursery and primary school classrooms from Building Bulletin 93.
Second Floor
The ambient noise level measured in a ground floor classroom facing the site was 39 dB(A). This is appreciably above the recommended upper limit of 35 dB(A) for nursery and primary school classrooms from Building Bulletin 93.
b. External
The existing ambient noise level measured outside the school for the
environmental statement was 59 dB(A). Building Bulletin 93 does not specify a recommended maximum external level for schools. However, it is
understood that a pending revision to the document by the Department for Education may specify that there should be at least one area suitable for teaching activities where ambient noise levels are below 50 dB(A). The noise measured level in the playground therefore indicates that the noise level in the playground does not currently meet this recommended level.
D. Existing Sound Insulation
a. New Building
The new building is approximately 6m high with a central clear span, External walls are rendered and the building has an aluminium double glazed curtain wall to the North elevation (which faces the proposed site) and clerestory windows to the east and west. The clerestory window are operable and the curtain wall has bottom hung windows clamped into the framing profiles 1000mm above finished floor level. There are two aluminium double glazed door to outside with weather seals.
The glazing for the new building is composed of 6mm / 16mm / 6mm double glazing for the glazed façade and 6mm / 20mm / 4mm double glazing on the external door.
The building is joined to the school reception and office via a short corridor an office face the school. The office has masonry wall with timber framed
punched windows facing the proposed site. The windows are double glazed with timber frames and have operable lights at high level.
The school lobby/ reception area has a lobby facing the proposed site with double glazed doors which open to the playground. There are three double glazed skylights to the area.
Based on the measurements taken on site, it is estimated that the sound insulation of the New Building is approximately 32 dB R’w when the automated windows are closed. This is about the same as the sound insulation identified by the Noise Insulation Regulations.
Extract ventilation served by a mechanical extract fan is on the roof ducted from a high level grille at the centre of the hall ceiling. Outside air is brought in by perimeter windows which are opened automatically. There are also
recirculating wall mounted fans which are running constantly to provide air movement from the back of the hall to improve the perception of comfort. On the basis of the survey it is not considered reasonably practicable to
provide improved sound insulation. The means for providing the additional ventilation and cooling is described in section 5.
b. Main Building
For the windows this is lower than the sound insulation identified by the Noise Insulation Regulations.
The main school building is a 3-storey typical Victorian-era school with loadbearing solid brick walls and large timber sash windows, some with circular vents in the window panes. The sash windows are glazed with a single layer of 3mm thick glass. The window are 1700 x 2000mm on the top floor with clerestory window in the pitched roof, 2900 x 1400mm on the middle floor and 2850 x 1400mm on the ground floor. There are a number of timber framed double access door at ground level to the classrooms.
On the basis of the survey information, improving the sound insulation of the windows would provide substantial additional protection against TTT
construction noise. The means for providing the additional noise insulation is described in the next section.
The current means of providing ventilation is by using the circular vents and opening windows. There is no mechanical ventilation for the building. The layout of each floor consists of a number of classrooms and staff rooms arranged around a central corridor. Most of these spaces are heated by radiators.
Ventilation and cooling to the classrooms is provided by opening the windows. Therefore improving the sound insulation of the windows would have to be supported by provision of additional ventilation / cooling and measures to reduce solar gain.
Based on the measurements taken on site, it is estimated that the sound insulation provided by the windows is approximately 20 dB R’w.
On the basis of the survey it is practicable to provide additional ventilation / cooling. The means for providing the additional ventilation is described in section 5.
c. Playground
Some existing protection of the playground is provided by the boundary wall. However this wall does not extend to the corner of the site and therefore would not provide significant mitigation from construction noise.
E. Trigger Levels for Noise Sensitive Spaces
a. Main Building
The noise levels to trigger the three levels of action under this plan for the Main Building are set 1m in front of the closest façade of the Main Building facing the TTT construction works, and are defined below for the time period 07:00 to 19:00: First Level (MB1) Second Level (MB2) Third Level (MB3) Indoor SOAEL, dB LpAeq,T 40 40 40 plus --Sound insulation 15 35 45 Façade correction 3 3 3 -- equals -- Outdoor SOAEL, dB LpAeq,T (A) 58 78 88 Outdoor existing facade ambient dB LpAeq,T (B) 62 62 62
The higher of (A) or (B) defines the trigger value
Outdoor façade trigger value dB LpAeq,T (B)
62 78 88
b. New Building
The noise levels to trigger the two levels of action under this plan for the New Building are set 1m in front of the closest façade of the New Building facing the TTT construction works, and are defined below for the time period 07:00 to 19:00:
First Level (NB1) Second Level (NB2)
Indoor SOAEL, dB LpAeq,T 49 52 plus --Sound insulation 15 32 Façade correction 3 3 -- equals -- Outdoor SOAEL, dB LpAeq,T (A) 67 84
First Level (NB1) Second Level (NB2) Outdoor existing
facade ambient dB LpAeq,T (B)
62 62
The higher of (A) or (B) defines the trigger value
Outdoor façade trigger value dB LpAeq,T (B)
67 84
c. Playground
The noise levels to trigger each action under this plan for the Playground are set at the boundary of the school, and are defined below for the time period 07:00 to 19:00:
First and Second Level (PG1 and PG2) Outdoor SOAEL, dB LpAeq,T (A) 62 Outdoor existing ambient dB LpAeq,T (B) 59
The higher of (A) or (B) defines the trigger value
Outdoor freefield trigger value dB LpAeq,T (B)
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