Flood Risk Assessment and Drainage Statement

Transcription

1 Trinity College, Cambridge Proposed Relocation of Felixstowe Rifle Range, Land north of Nicholas Road, Trimley St Mary, Felixstowe

2 Quality Assurance Site name: Client name: Proposed Relocation of Felixstowe Rifle Range, Land north of Nicholas Road, Trimley St Mary, Felixstowe Trinity College, Cambridge Type of report: Flood Risk Assessment and Drainage Statement Prepared by: Jon Frith, Partner, Bidwells Consulting Engineers Signed Date Reviewed by: Richard Martin, Senior Civil Engineer, Bidwells Consulting Engineers Signed Date

3 Table of Contents 1 Introduction Development Description and Location Flood Hazards Flood Risk Management Measures Surface Water Drainage Strategy Foul Water Drainage Strategy Offsite Impacts Remaining Flood Risks Conclusions Appendices Appendix A - Appendix B - Appendix C - Appendix D - Appendix E - Appendix F - Topographical Survey Site Photos Development Area Plan Desktop Study Extracts Surface Water Drainage Calculations Indicative Drainage Layout

4 1 Introduction 1.1 Bidwells Consulting Engineers have been commissioned by the Bidwells Planning team on behalf of Trinity College to prepare a Flood Risk Assessment and Drainage Statement to support the Planning Application for the proposed relocation of Felixstowe Rifle Range to land north of Nicholas Road, Trimley St Mary, Felixstowe. This assessment report has been prepared in accordance with the National Planning Policy Framework (NPPF) and the NPPF Technical Guidance documents (retaining elements of PPS25). 1.2 The purpose of this report is to provide information on the flood risks associated with the application site and present appropriate mitigation measures for the proposed development. This is to enable the development to obtain Planning Permission without an objection from the Local Planning Authority or their consultees and demonstrate that the site, its occupants and the surrounding development is at the minimum risk of flooding. 1

5 2 Development Description and Location Location 2.1 The site is located to the south of Trimley St Mary and to the west of Felixstowe in Suffolk. The site can be identified by the Ordnance Survey Grid Reference , The site is shown in figures 3.1, 3.2 and the aerial photo 3.3 below. Figure 3.1 Large scale site location plan of the site, Figure 3.2 Small scale site location plan, 2

6 Figure Aerial photo Existing Site Layout 2.2 The development boundary encloses an area of 16,832m 2. The site is currently greenfield, with the northern boundary formed by earthwork bunding installed as part of the mitigation measures understood to be associated with nearby commercial development. The southern boundary is formed by an existing ditch separating the site from the embankment supporting the Felixstowe Port railway line. To the east of the development is greenfield up to where it meets the railway line that curves round to the north. The western boundary is defined by an area of tree planting separating the site from a bridal way. 2.3 A topographical survey of the existing site layout had been undertaken to GPS datum and is shown in Appendix A. The site currently has a fall from north to south with levels at the base of the earth bund along the northern boundary at approximately 16.5m. The levels along the southern boundary adjacent to the ditch being are approximately 11.5m. 2.4 The watercourse along the southern boundary is approximately 3m deep and 5m wide at the top of the bank. Sections of the watercourse have concrete bed and banks supporting headwalls controlling the flows in a southerly direction. To the south west of the site boundary the 3

7 watercourse is diverted under the railway embankment in a 1.2m diameter culvert. At the time of inspection, surface water was running freely through the watercourse and culvert. 2.5 See Appendix B for site photos. Proposed Development 2.6 The proposed development as shown in Appendix C comprises the relocation of Felixstowe Rifle Club including the adaption of the existing earth bunding to the north, as well as the installation of new earthwork bunding, two open rifle ranges both with permeable surfacing, a covered firing point, a club house, an air gun range and associated car parking. Access to the site will be via Bridal Way 14 to the south of the site, which in turn connects to Nicholas Road that abuts the ports container park. Geology 2.7 The Geo Insight data has been purchased for the site, extracts of which are included within Appendix D. Based on the British Geological Survey (BGS) 1:50,000 Digital Geological Map of Britain, the site is underlain with a bedrock of London Clay Formation Clay, Silt and Sand. There are no superficial deposits shown. The Geo Insight data records a permeability of the bedrock as ranging from moderate to very low. Hydrogeology 2.8 The Ground Sure Enviro Insight reports have been purchased for the site which indicate the site is underlain with a unproductive aquifer within the underlying bedrock The data indicates the site is not within a source protection zone and does not highlight any potable water abstraction licences within 500m of the site. Hydrology 2.10 A detailed river network map identifies the watercourse along the southern boundary is an unnamed Drain classified as a Tertiary River and it is shown to flow in a southerly direction (via a culvert under the railway embankment) into an unnamed Drain classified as a Secondary River that follows the route of Bridle Way 14. 4

8 Flood Zone Delineation 2.11 The Environment Agency s (EA) indicative flood maps are shown in Figure 3.4 and 3.5 below and highlight the proposed development is located within Flood Zone 1. The maps indicate the closest area of Flood Zone 2 and 3 associated with tidal and fluvial flooding are located approximately 1km to the south and west of the development site. Figure 3.4 large scale indicative flood map Figure 3.5 small scale indicative flood map 5

9 Vulnerability Classification 2.12 The NPPF and the relevant technical guidance incorporates PPS25 Table D.2. This table provides a detailed list of which types of development fall into the vulnerability classifications, also defined within PPS25. This list is recognised as not being exclusive and provides guidance on the various uses and their subsequent flood risk vulnerability classification The proposed development comprises a rifle club and would be considered within the category of 'Leisure' and therefore falls into the classification of 'Less Vulnerable. Sequential and Exception Tests 2.14 The proposed development is classified as Less Vulnerable and is located within Flood Zone 1. Therefore in accordance with the NPPF Technical Guidance document, the Sequential and Exception Tests are not required to be undertaken by the Local Planning Authority as part of the planning process. 6

10 3 Flood Hazards Source of Flooding Fluvial 3.1 Fluvial flooding is flooding caused by rivers and occurs when the river channel capacity is exceeded by the flow. Most rivers have a natural floodplain which in built up areas is sometimes encroached upon by development. The closest area of Fluvial flood risk is approximately 1km to the west of the development and does therefore not present a risk to the site. Tidal 3.2 Tidal flooding from the sea occurs when high tides and storm surges raise the level of tidal waters above the level of the shore or river bank. They can be sudden and severe, but are dependent upon a number of factors. The closest area of Tidal flood risk is approximately 1km to the south and does therefore not present a flood risk to the site. Overland Flow 3.3 In areas of development it is possible during high intensity rainfall storms for surface water to not be able to soak into the ground or enter the man-made drainage system at a quick enough rate to cope with the volume of water. Where this occurs, the excess water can flow across land and potentially cause flooding. The topography of the site falls from the north to south. Land to the north of the site is separated by the earthwork bund and therefore there is no risk of overland flow from third party land. The risk of overland flow from the development site onto third party land is mitigated by the unnamed watercourse along the southern boundary that would intercept any flows. Groundwater 3.4 In areas where the level of groundwater is high, rainfall that soaks into the ground can raise it to a level where structures within the ground are at risk of flooding. Structures such as basements or detention ponds can be at risk, although this is dependent upon the ground conditions of the site. There is a risk of perched ground water in this area but this would be mitigated during detailed design of the underlying sub-base and drainage. Sewers 3.5 Flooding from sewers occurs when the quantity of water flowing into the sewers exceeds the capacity of the sewer and backs up to an extent where it floods out of manholes or gullies. Alternatively and more commonly, sewers flood when a blockage occurs in a pipe. This is more 7

11 likely on private sewers, but is usually less severe than flooding from larger public sewers which can cause extensive flooding due to the greater quantity of surface area which they drain. Artificial Sources 3.6 Non-natural or artificial sources of flooding can include reservoirs, canals and lakes where water is retained above the natural ground level and flooding may occur as a result of the facility being overwhelmed and/or as a result of dam or bank failure. There are no artificial sources of flooding in close proximity to the site and therefore there are no associated significant risks. Description of Flooding 3.7 The site is considered to be at a low risk of flooding, with the exception of the following; Given the limited extend of impermeable area sewer flooding is considered to be a medium to low risk and an appropriately detailed drainage system would need to be designed and constructed as part of the development proposal; Overland flow from the development to the south is considered a low risk associated with the relatively steep topography of the site. However, the vast majority of the proposed development is to be permeable and the ditch to the south of the site would intercept any overland flow. 3.8 PPPS25 Table D.3 (as part of the retained technical guidance to NPPF) highlights that less vulnerable development is permitted within Flood Zone 1 and therefore the focus of this report will be to implement an appropriate surface and foul water drainage strategy to mitigate the risk accordingly. Measures implemented into the design of the development to mitigate the potential effects of sewer flooding will also mitigate the potential effects of flooding from other sources, such as overland flow and the residual risk of sewer blockage. Access and Egress 3.9 The proposed development is located within Flood Zone 1 and therefore during fluvial and tidal storm events up to and including 1000 year storm event, access and egress have been classified as safe (over dry land). 8

12 4 Flood Risk Management Measures 4.1 To enable the site to be considered in line with the NPPF and the Technical Guidance, appropriate flood mitigation measures need to be in place. The measures laid out below are put forward as those that will be incorporated during the detailed design and operation of the development. Level Regime Finished Floor Level 4.2 The Finished Floor Levels (FFLs) of any proposed buildings will be at least 500mm above the top of bank level of the adjacent watercourse. External Levels 4.3 We are not aware of any historical flooding that impacts on the existing development that highlights that overland flow is not considered as a risk for this development. All proposed new hardstanding areas will be designed to fall away from the proposed buildings so that in the event of a sewer surcharging or overland flow flood event, the flood water will not enter the buildings but instead will be directed towards the watercourse along the southern boundary. Surface Water Drainage Strategy 4.4 The surface water drainage strategy for the proposed development will be carried out in accordance with Section 5 of this report. Foul Water Drainage Strategy 4.5 The foul water drainage strategy for the proposed development will be carried out in accordance with section 6 of this report. Detailed Design 4.6 It is proposed that the mitigation measures set out above are controlled by conditions to the planning consent which will be approved by the LPA and their consultees. 9

13 5 Surface Water Drainage Strategy Climate Change 5.1 There is one element of climate change that will affect flood risk at the application site which is the peak rainfall intensity. In accordance with Tables 4 and 5 of the NPPF Technical Guidance Document climate change is dependent upon the design life of the development. For a site intended for leisure use it is considered to take the range of which equates to a design life of years. 5.2 This will result in an increase to the peak rainfall intensity of 20% which has been incorporated into the surface water drainage strategy described overleaf. Surface Water Run Off Rate 5.3 The existing site layout consists of permeable undeveloped open grassland with a surface water discharge equal to the Greenfield run-off rates as shown in Table 6.1 below (with and without the effects of Climate Change). The flow rates have been calculated using the IH 124 method taking into account the existing site conditions. Return Period Existing Discharge Rate Existing Discharge Rate (+20%) 1 in 1 year 2.3 l/s 3.0 l/s 1 in 30 year 6.5 l/s 8.5 l/s 1 in 100 year 9.6 l/s 12.5 l/s Table 6.1 Existing Site Run-off Rates 5.4 The proposed development has an impermeable area of 810m2. Without any mitigation measures put in place the development would produce unrestricted flow rates via a piped outfall as shown in Table 6.2 below. Flow rates have been calculated using micro drainage design (Colbrook-White method) incorporating the FSR rainfall parameters for the site during a 15 minute winter event. 10

14 Return Period Proposed Piped Outfall Discharge Rate Proposed Piped Outfall Discharge Rate (+20%) 1 in 1 year 12.1 l/s 15.7 l/s 1 in 30 year 29.7 l/s 38.6 l/s 1 in 100 year 38.6 l/s 50.1 l/s Table 6.2 Potential Site Run-off Rates 5.5 As the impermeable area is small in comparison with the remaining site the site run-off rates have been calculated assuming an urbanisation factor of 10% to account for the roofs of the proposed buildings. This gives rise to a nominal increase in run-off rates as indicated within Table 6.3 below. Return Period Existing Discharge Rate Proposed Discharge Rate 1 in 1 year 2.3 l/s 2.8 l/s 1 in 1 year (+20%) 3.0 l/s 3.6 l/s 1 in 30 year 6.5 l/s 7.5 l/s 1 in 30 year (+20%) 8.5 l/s 9.8 l/s 1 in 100 year 9.6 l/s 10.6 l/s 1 in 100 year (+20%) 12.5 l/s 13.8 l/s Table 6.3 Existing Discharge Rates and Proposed Discharge Rates assuming a 10% urbanisation factor 5.6 Table 6.3 demonstrates that with the relatively small increase in impermeable area the resultant increase in discharge rates from the site is nominal. However, to mitigate this nominal increase in surface water run off a drainage strategy is proposed within Section 6 of the report. Proposed Surface Water Drainage Strategy 5.7 The development will incorporate a sustainable drainage system (SuDS) that suits the site conditions and location. All sites have constraining factors which mean that certain SuDS solutions may be restricted. The proposed surface water drainage strategy is highlighted on an indicative sketch included as Appendix F. 11

15 Infiltration Drainage 5.8 In accordance with PPS25 (a retained element of the technical guidance to NPPF) infiltration drainage has been considered at an early stage as the development drainage strategy. The Geo Insight data identifies there are no superficial deposits on site and that the underlying bedrock is London Clay Formation Clay, Silt and Sand. The Geo Insight data highlights that the anticipated permeability of the underlying soils ranges from moderate to very low. 5.9 Ground conditions within the site are therefore not thought to be appropriate to support the use of high intensity infiltration drainage techniques such as soakaways. During the detailed design infiltration testing should be undertaken in accordance with BRE365 to obtain the soil infiltration rate for the site. Should percolation tests show that soil conditions are suitable for infiltration devices, the drainage strategy could be designed to meet the following design criteria. Contain a critical 1:100 year storm event with a 20% increase in rainfall intensity to allow for the effects of climate change; Have a half drain time of less than 1440 minute (1 day) unless additional storage is provided to contain subsequent storm events; Establish the long term maintenance and ownership of the drainage system Given the expected infiltration rate within the London Clay Formation it is likely that the use of a Type B permeable paving solution (with gravel finish) will be the most appropriate form of infiltration drainage. Given the anticipated low permeability rates of he London Clay the depth of permeable sub-base is expected to be between 350 and 450mm thick and this would be verified by site specific infiltration testing. The Type B system would be detailed to have a network of perforated pipes at high level within the permeable sub-base that would act as an overflow into the adjacent watercourse. Pollution Control 5.11 Pollution control measures should be put in place during the detailed design in accordance with CIRIA 697 to reduce the risk of contaminates entering the watercourse or ground water table. The private roads/drives and adoptable highway will present the highest pollution risk from this source and some of the pollution control measures for these area could include the use of: permeable paving (gravel finish with permeable sub-base); catchpit manholes; T-shaped outlet pipes on the final manholes prior to discharging into the permeable subbase construction to the permeable paving. 12

16 5.12 The pollution control measures listed above form part of the positive drainage network that will drain the proposed development. Further pollution control measure could also be implemented in to the drainage strategy with the careful selection of SuDS techniques subject to detailed design and site specific infiltration testing. 13

17 6 Foul Water Drainage Strategy 6.1 Foul water flows are expected to be very low for the site. There are no public sewers in close proximity to the site. And it is therefore proposed to discharge to a package treatment plant with an overflow into the network of perforated pipes under the car park. This will filter the run off before potentially overflowing to the watercourse during an extreme storm event if the permeable subbase is saturated. 6.2 As the scheme progresses to detailed design the Environment Agency would be contacted in relation to the requirements for a permit to discharge for the package treatment system. The location of the package treatment plant has been indicated on the drainage layout included within Appendix F and indicates a location adjacent to the car park to ease maintenance access.. 14

18 7 Offsite Impacts Impact of Development and Hydrological Morphology 7.1 The application site is located within Flood Zone 1 and therefore the proposed development is not located within the fluvial path of any watercourse and will not occupy any critical flood plain storage. Therefore the development will have no major impact on the hydrological morphology of the surrounding area. Impact and Surface Water Drainage 7.2 The impermeable area generated by the proposed development is approximately 810m2 more than the existing (fully permeable) site. The proposed surface water drainage strategy as detailed within Section 5 of this report is likely to comprise the following:- Using an urbanisation factor on the existing discharge rates highlights that the relatively small increase in impermeable areas results in a nominal increase in the site run-off discharge rates. To mitigate the nominal increase in discharge rates it is proposed that the roof to the new buildings discharge via catchpit manholes into the permeable sub-base underlying the proposed permeable car park through a network of perforated pipes. The car park will be Type B permeable paving system (such as gravel) with a depth of subbase between mm to provide attenuation for the run off from the proposed buildings. The final depth of sub-base is subject to onsite infiltration testing. A network of perforated pipes would be placed in the upper layer of the permeable sub-base to act as an overflow to discharge to the adjacent watercourse;. 15

19 8 Remaining Flood Risks 8.1 The main residual flood risks to be considered is that from the proposed blockage/surcharging of sewers which cross the site. Should the maintenance of these structures not be undertaken then there is an increased risk that they could cause flooding. Risk Management Responsibility 8.2 The maintenance and repair of the private sewer network within the site can be dealt with by the maintenance regime to be undertaken by the Client. Maintenance Regimes 8.3 The recommended maintenance regime for the private storm and foul water drainage system is set out below: Maintenance Regime Inspection and clearance of all gullies, channel drains, Inspection Chambers (IC) and Catchpit Manholes to be undertaken on an annual basis; Inspection and clearance of all gutters and filter meshes to be undertaken on an annual basis. 8.4 The maintenance regime recommended above is put in place to minimise the risk of blockages occurring and to prevent water surcharging from the inspection chamber. However if flooding from the drainage system occurs then the cause should be identified and dealt with immediately. 16

20 9 Conclusions 9.1 This Flood Risk and Drainage Assessment demonstrates that the proposed development: 1) is not subject to the sequential and exception tests during the planning process. 2) is at a low risk of flooding from all sources. 3) will provide a suitable surface water drainage strategy to drain the site and reduce flood risk overall. 4) will provide a suitable foul water drainage strategy to drain the site. 9.2 The report has been undertaken in accordance with the Technical Guidance documents of Planning Policy Statement (PPS) 25 and the National Planning Policy Framework (NPPF). 17

21 Appendix A Topographical Survey

22 S SY SY OVERGROWTH OVERGROWTH GRASS GRASS

23 Appendix B Site Photos

24 Flood Risk & Drainage Statement Photo 1 View looking west along southern boundary Photo m culvert to west of site Photo 3 Culvert cutfall to the south of railway Photo 4 View of unnamed watercourse along embankment southern boundary Photo 5 View looking north from southern boundary Photo 6 View looking west along northern boundary

25 Appendix C Proposed Development Location Plan and Layout

26 S1 S2 A 25/10/11 Updated in accordance with Rifle Club comments TPN bh J n NOTES rev. date description drn chk'd Do not scale from this drawing, use figured dimensions only. All dimensions to be checked on site. All drawings to be read in conjunction with other contract documentation. Any discrepancies to be reported to the Contract Administrator before any work commences. Copyright Bidwells LLP K 14 A 50m range with 10no firing points 100 yard range with 10no firing points Proposed rifle club premises G 05/04/13 Site boundary amended TPN bh F 05/02/13 Revised following discussions with Acoustic Consultant - Revised Planning Issue TPN bh E 10/07/12 Preliminary Planning Issue TPN bh D 02/12/11 Red and blue ownership boundaries added TPN bh C 21/11/11 Minor amendments to position of clubhouse and air gun range TPN bh B 25/10/11 Position of 100 yard range adjusted in accordance with Rifle Club comments TPN bh 14 L B C Proposed landscaping within site boundary area to be as detailed by Terra Firma Landscape Architects, see drawings No and Proposed indoor range Existing air gun range (to be relocated from current rifle club premises) number one legg street chelmsford cm1 1js client: Trinity College Cambridge title: Site Location Plan drawn TPN project: Rifle Club Premises Trimley St Mary, Felixstowe status: chk'd planning bh discipline project no. dwg no. rev. building surveying U date: 26/09/11 A1 1:1250 G

27 17.29 C1 C OVERGROWTH Sand Catcher A A GRASS B1 B A A Sand Catcher Shaded areas indicate bunds to be formed to ranges A A3 S SY SY A Indoor Range 7m x 54m FFL A Dashed lines indicate 3m high acoustic fencing to top of side bunds A A Covered Firing Point FFL Club House/ Armoury FFL C C Air Gun Range FFL Car Park B B NOTE: For details of landscaping to site refer to Terra Firma Landscape Architects drawings No and n LEGEND: Indicates existing level Indicates proposed level H 05/04/13 Site boundary amended TPN bh G 05/02/13 Layout revised following further consultation with Acoustic Consultant TPN bh F 20/11/12 Layout revised following consultation with Acoustic Consultant TPN bh E 10/07/12 Car parking added. Planning Issue TPN bh D 02/12/11 Size of air gun range adjusted TPN bh C 21/11/11 Minor amendments to position of clubhouse and air gun range and proposed TPN bh levels added B 25/10/11 Position of 100 yard range adjusted in accordance with Rifle Club comments TPN bh A 25/10/11 Updated in accordance with Rifle Club comments TPN bh rev. date description drn chk'd NOTES Do not scale from this drawing, use figured dimensions only. All dimensions to be checked on site. All drawings to be read in conjunction with other contract documentation. Any discrepancies to be reported to the Contract Administrator before any work commences. Copyright Bidwells LLP client: project: discipline Trinity College Cambridge Rifle Club Premises Trimley St Mary, Felixstowe number one legg street chelmsford cm1 1js title: status: project no. Block Plan planning dwg no. building surveying U drawn TPN chk'd rev. bh date: 28/09/11 A3 1:500 H

28 Appendix D Extracts of geological and hydrological data

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45 Appendix E Surface Water Drainage Calculations

46 Bidwells Page 1 Stonecross Trinity College Trumpington High Street Felixstowe Rifle Range Cambridge CB2 9SU Trimley St Mary Date March 2012 Designed by RSM File Checked by Elstree Computing Ltd Source Control W.12.6 ICP SUDS Mean Annual Flood Input Return Period (years) 1 SAAR (mm) 550 Urban Area (ha) Soil Region Number Region 5 Results l/s QBAR Rural 2.7 QBAR Urban 2.7 Q1 year 2.3 Q1 year 2.3 Q30 years 6.5 Q100 years Micro Drainage Ltd

47 Bidwells Page 2 Stonecross Trinity College Trumpington High Street Felixstowe Rifle Range Cambridge CB2 9SU Trimley St Mary Date Designed by RSM File Checked by Elstree Computing Ltd Source Control W.12.6 ICP SUDS Mean Annual Flood Input Return Period (years) 1 SAAR (mm) 550 Urban Area (ha) Soil Region Number Region 5 Results l/s QBAR Rural 2.7 QBAR Urban 3.2 Q1 year 2.8 Q1 year 2.8 Q30 years 7.5 Q100 years Micro Drainage Ltd

48 Appendix F Indicative Drainage Layout

49 OVERGROWTH GRASS S SY SY OVERGROWTH INDICATES PERMEABLE SURFACE AND EARH BUNDS INDICATES FOUL WATER DRAINAGE SYSTEM DISCHARGING TO PACKAGE TREATMENT PLANT WITH DISCHARGE TO NETWORK OF PERFORATED PIPES GRASS INDICATES IMPERMEABLE ROOF AREA (APPROXIMATELY 810m2) TO DISCHARGE TO BELOW GROUND DRAINAGE SYSTEM THAT LINKS VIA CATCHPIT MANHOLE TO THE NETWORK OF PERFORATED PIPES UNDER THE CAR PARK TYPE B PERMEABLE PAVING SYSTEM (GRAVEL SURFACE OVER mm DEPTH OF PERMEABLE SUB-BASE) TO ALLOW INFILTRATION INTO THE UNDERLYING SOILS (ASSUMED TO BE LIMITED BY LOW TO MODERATE PERMEABILITY OF SOILS) WITH A NETWORK OF PERMEABLE PIPES TO OVERFLOW INTO ADJACENT WATERCOURSE UNNAMED WATERCOURSE FLOWING IN A SOUTHERLY DIRECTION INDICATIVE FOUL WATER DRAINAGE NETWORK INDICATIVE SURFACE WATER DRAINAGE NETWORK DESIGNED NOT TO FLOOD DURING 1 IN 100 YEAR STORM EVENT (+ 20%) n DISCHARGE FROM OVERFLOW TO PERMEABLE PAVING INTO UNNAMED WATERCOURSE. UNCONTROLLED DISCHARGE AS CALCULATED FLOW RATES LESS THAN 5l/s. THE DRAINAGE LAYOUT SHOWN IS SUBJECT TO DETAILED DESIGN AND IS INTENDED TO SHOW THE SURFACE WATER DRAINAGE PRINCIPLES AND THE POLLUTION MITIGATION MEASURES NOTES Do not scale from this drawing, use figured dimensions 16 upper king street norwich nr3 1ha only. All dimensions to be checked on site. All drawings to be read in conjunction with other contract documentation. Any discrepancies to be reported to the Contract client: project: TRINITY COLLEGE AND FELIXSTOWE RIFLE CLUB RELOCATION OF FELIXSTOWE RIFLE CLUB title: status: INDICATIVE DRAINAGE STRATEGY PRELIMINARY drawn PW chk'd JF date: A3 1: /--/ rev. date description drn chk'd Administrator before any work commences. Copyright Bidwells LLP discipline project no. dwg no. CIVIL ENGINEERING - SK-100 rev. P1