A428 Black Cat to Caxton Gibbet improvements
TR010044 Volume 6 6.3 Environmental Statement Appendix 13.6: Water Resources Data
Planning Act 2008 Regulation 5(2)(a) Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009
26 February 2021
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Infrastructure Planning
Planning Act 2008
The Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009
A428 Black Cat to Caxton Gibbet improvements Development Consent Order 202[ ]
Appendix 13.6: Water Resources Data
Regulation Number Regulation 5(2)(a) Planning Inspectorate Scheme TR010044 Reference Application Document Reference TR010044/APP/6.3
Author A428 Black Cat to Caxton Gibbet improvements Project Team, Highways England
Version Date Status of Version Rev 1 26 February 2021 DCO Application
Planning Inspectorate Scheme Ref: TR010044 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Table of contents
Chapter Pages 1 Introduction 1 1.1 Purpose of this report 1 2 Known Licenced Water Abstractions 2 3 Known Active Permitted Discharges to Water Bodies 5 4 Summary of geology, hydrogeology and soils 12 5 Details on key watercourses 13 5.1 River Great Ouse 13 5.2 Rockham Ditch 14 5.3 South Brook 25 5.4 Begwary Brook 36 5.5 Stone Brook 36 5.6 Hen Brook 37 5.7 Wintringham Brook 38 5.8 Fox Brook 39 5.9 Gallow Brook 39 5.10 West Brook 40 5.11 Bourn Brook 41 6 Summary of aquatic ecology 42 6.1 River Great Ouse 42 6.2 Stone Brook 43 6.3 Begwary Brook 43 6.4 Hen Brook 44 6.5 West Brook 44 6.6 Bourn Brook 45 6.7 Other watercourses 45
Table of Tables Table A1: Abstraction Licences
Table A2: Discharge Consents
Table A3: Known pollution incidents within 2 kilometres (1.2 miles) of the Scheme as provided by the EA
Planning Inspectorate Scheme Ref: TR010044 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
1 Introduction
1.1 Purpose of this report This appendix contains the details of abstractions, discharges, pollution incidents, descriptions of water bodies and their attributes, geology, hydrogeology and soils, and aquatic ecology for the study area and water bodies within the study area, as defined in Chapter 13, Road drainage and the water environment of the Environmental Statement [TR010044/APP/6.1]. Please refer to Chapter 13, Road drainage and the water environment of the Environmental Statement [TR010044/APP/6.1] for full details of reference sources, abbreviations and interpretation of this data and information. These are shown on Figure 13.1 of the Environmental Statement [TR010044/APP/6.2].
Planning Inspectorate Scheme Ref: TR010044 1 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
2 Known Licenced Water Abstractions
Table A1: Abstraction Licences (Source : EA)
Groundwater Licence Holder Figure (GW) or Name Licence Number Reason for Abstraction Reference Surface Water (SW)
Breedon Southern A1 AN/033/0012/010 GW Dewatering Limited
A2 6/33/12/*S/0019 SW Spray Irrigation - Direct L V DAVISON & SON
BURLINGTON A3 6/33/12/*S/0100 SW Spray Irrigation - Direct FARMS LTD
A4 6/33/12/*S/0152/R01 SW Spray Irrigation - Direct R P GATES & SONS
BURLINGTON A5 6/33/12/*S/0123 SW Spray Irrigation - Direct FARMS LTD
A6 6/33/12/*S/0035 SW Spray Irrigation - Direct S W BUMSTEAD
A7 6/33/19/*S/0047 SW Spray Irrigation - Direct L V DAVISON & SON
A8 6/33/19/*S/0136 SW Spray Irrigation - Direct Mr B Yousaf
A9 AN/033/0019/001/R01 SW Spray Irrigation - Direct J F and P J Quince
A10 AN/033/0019/002/R01 SW Spray Irrigation - Direct Mr B Yousaf
DA CR MR & PH A11 6/33/19/*S/0067 SW Spray Irrigation - Direct ZWETSLOOT
BURLINGTON A12 6/33/19/*S/0113 SW Spray Irrigation - Direct FARMS LTD
A13 6/33/19/*G/0114 GW Spray Irrigation - Direct J F and P J Quince
General Farming & A14 6/33/19/*G/0105 GW Domestic J F and P J Quince
DA CR MR & PH A15 6/33/19/*S/0089 SW Spray Irrigation - Direct ZWETSLOOT
A16 6/33/19/*S/0096 SW Spray Irrigation - Direct E J STOCKER
BATES BROS A17 6/33/20/*S/0013 SW Spray Irrigation - Direct (FARMS) LTD
Planning Inspectorate Scheme Ref: TR010044 2 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Groundwater Licence Holder Figure (GW) or Name Licence Number Reason for Abstraction Reference Surface Water (SW)
CHAWSTON A18 IRRIGATION 6/33/20/*S/0131/R01 SW Spray Irrigation - Direct MANAGEMENT
A19 6/33/20/*G/0031
A20 6/33/20/*G/0134 GW Spray Irrigation - Direct E WOOTTON
General Use Relating to A21 Secondary Category E F WOOTTON & 6/33/20/*S/0052 SW (Medium Loss) SON
S A MERTON- A22 JONES & R 6/33/20/*G/0039 GW Spray Irrigation - Direct MERTON-BARRETT
S A MERTON- A23 JONES & R 6/33/20/*S/0069 SW Spray Irrigation - Direct MERTON-BARRETT
Spray Irrigation - JOHN SHEARD A24 6/33/20/*S/0091 SW Storage (FARMS) LTD
WYBOSTON LAKES A25 AN/033/0020/009 GW Spray Irrigation - Direct LTD
RWE Generation UK A26 6/33/20/*S/0116/R01 SW Evaporative Cooling PLC
Hydroelectric Power Eaton Socon Hydro A27 AN/033/0020/001 SW Generation Limited
A28 6/33/20/*S/0030 SW Spray Irrigation - Direct P SQUIRE
Spray Irrigation - ST NEOTS GOLF A29 6/33/20/*S/0124 SW Storage CLUB
ST NEOTS GOLF A30 6/33/20/*S/0130A/R01 SW Spray Irrigation - Direct CLUB
HAIL WESTON A31 6/33/21/*S/0025 SW Spray Irrigation - Direct FARMS LTD
Spray Irrigation - A32 6/33/21/*S/0047 SW Storage T J R & J L PIGG
A33 6/33/21/*S/0009 SW Spray Irrigation - Direct G T RAMPLY & SON
Planning Inspectorate Scheme Ref: TR010044 3 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Groundwater Licence Holder Figure (GW) or Name Licence Number Reason for Abstraction Reference Surface Water (SW)
Make-Up Or Top Up HUNTINGDONSHIRE A34 6/33/22/*S/0039 SW Water DISTRICT COUNCIL
General Use Relating to A35 Secondary Category HUNTINGDONSHIRE AN/033/0022/001 GW (Very Low Loss) DISTRICT COUNCIL
Planning Inspectorate Scheme Ref: TR010044 4 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
3 Known Active Permitted Discharges to Water Bodies
Table A2: Known Active Permitted Discharges to Water Bodies (Source: EA)
Figure Licence Holder Discharge Type Receiving Waters Reference Number
Abbotsley Road D1 Pumping Pumping Station on Ditch (tributary of Hen AWCNF11485 Station Sewerage Network Brook)
Domestic property D2 PRCNF05022 North Farm (single) (incl. farm house) Fox Brook
WwTW (not water co) D3 (not STP at a private Ditch (tributary of Gallow PRCNF14832 Whitehall Farm premises) Brook)
WwTW (not water co) D4 Cambridgeshire (not STP at a private Ditch (tributary of Gallow PRCNF17425 Chemicals premises) Brook)
Domestic property Ditch (tributary of D5 EPRKP3822XC Manor Farm (single) (incl. farm house) Eastern Brook)
Pumping WwTW/Sewage D6 Station Treatment Works (water Ditch (tributary of AW1NF286 Conington company) Eastern Brook)
Farms (not house)/Crop D7 Brook End + Animal Rearing/Plant Ditch (tributary of Hen GWCLF30367 Farm Nursery Brook)
Caxton Road Pumping Station on D8 Pumping Sewerage Network Ditch (tributary of AWCNF11477 Station (water company) Eastern Brook)
Tempsford Water WwTW/Sewage D9 Recycling Treatment Works (water Ditch (tributary of Stone AWCNF1223 Centre company) Brook)
Roxton (School WwTW/Sewage D10 Lane) Pumping Treatment Works (water Ditch (tributary of River AWCNF11935 Station company) Great Ouse)
Black Cat Mineral/Gravel Ditch (tributary of River D11 EPRHP3724GA Roundabout Extraction/Quarrying Great Ouse)
Shop incl. Garden D12 Centre/Retail Trade (not Ditch (tributary of River PRCLF14267 Shell Fortune Motor Vehicle) Great Ouse)
Planning Inspectorate Scheme Ref: TR010044 5 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Figure Licence Holder Discharge Type Receiving Waters Reference Number
WwTW (not water co) D13 (not STP at a private PRCNF01483 Bridge Farm premises) South Brook
WwTW/Sewage D14 Treatment Works (water Ditch (tributary of River AW1NF950 Chawston STW company) Great Ouse)
WwTW/Sewage D15 Little Treatment Works (water Ditch (tributary of River AW1NF462A Barford STW company) Great Ouse)
WwTW (not water co) D16 Little Barford (not STP at a private PRCNF05375 Power Station premises) River Great Ouse
WwTW/Sewage D17 Treatment Works (water Ditch (tributary of River AW1NF2721 Roxton STW company) Great Ouse)
WwTW/Sewage D18 Treatment Works (water Ditch (tributary of River AW1NF759 Sandy STW company) Ivel)
Abbey Making of Paper+Paper Ditch (tributary of River D19 PR1NF2984 Corrugated Ltd Products Ivel)
Storm Tank/CSO on D20 Sewerage Network Ditch (tributary of River AW1NF907 Sandy (water company) Ivel)
Surface Water Storm Tank/CSO on D21 Outfall Sewer Sewerage Network Ditch (tributary of River AW1NF834 at Sandy (water company) Ivel)
WwTW (not water co) D22 (not STP at a private Ditch (tributary of River PRCNF14384 Highfield Farm premises) Ivel)
Domestic property D23 (multiple) (incl. farm Tributary of River Great EPRHB3690DK High Street houses) Ouse
WwTW/Sewage D24 Great Barford Treatment Works (water Tributary of River Great AW1NF1179A STW company) Ouse
Farms (not house)/Crop D25 Zwetslotts + Animal Rearing/Plant Ditch (tributary of River PRCNF14060 Nursery Nursery Ivel)
Planning Inspectorate Scheme Ref: TR010044 6 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Figure Licence Holder Discharge Type Receiving Waters Reference Number
Grange Road Pumping Station on D26 Pumping Sewerage Network Ditch (tributary of River AWCNF11079 Station (water company) Ivel)
Making of Other D27 Transport Tributary of River Great PR1NF1651 Roxton Road Equip/Ships/Trains/Bikes Ouse
WwTW/Sewage D28 Treatment Works (water AW1NF932 Royal Oak company) Tributary of Stone Brook
Storm Tank/CSO on D29 Tempsford Sewerage Network AW1NF1254 Depot (water company) Tributary of River Ivel
WwTW (not water co) D30 (not STP at a private PRCNF05125 Station Farm premises) Stone Brook
WwTW/Sewage D31 Tithe Farm Treatment Works (water Tributary of Colmworth AW1NF1584 STW company) Brook
Ermine Street Pumping Station on D32 Pumping Sewerage Network AWCNF11473 Station (water company) Bourn Brook
Barford Road Pumping Station on D33 Pumping Sewerage Network Drain (upstream of River AW1NF2244 Station (water company) Great Ouse)
Cambourne Pumping Station on D34 Main Pumping Sewerage Network Ditch (upstream of ASCNF11450 Station (water company) Bourn Brook)
Duck Lane Pumping Station on D35 Pumping Sewerage Network AWNNF2263 Station (water company) Hen Brook
Domestic property D36 (multiple) (incl. farm Ditch (upstream of PRCLF03347 The Oaks houses) Bourn Brook)
WwTW (not water co) D37 (not STP at a private PR1NF2098 Caravan Site premises) Wintringham Brook
Planning Inspectorate Scheme Ref: TR010044 7 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Figure Licence Holder Discharge Type Receiving Waters Reference Number
Cemetery Road Pumping Station on D38 Pumping Sewerage Network Drain (upstream of Hen AWCNF2783 Station (water company) Brook)
Brampton Pumping Station on D39 Pumping Sewerage Network AW1NF385 Station (water company) Wintringham Brook
Cemetery Lane Pumping Station on D40 Pumping Sewerage Network Drain (upstream of Hen AW1NF583 Station (water company) Brook)
St Neots – Storm Tank/CSO on D41 Market Square Sewerage Network AW1NF2577 CSO (water company) River Great Ouse
WwTW/Sewage D42 Treatment Works (water AWCNF6 Duloe STW company) Duloe Brook
Huntington Pumping Station on D43 Street Pumping Sewerage Network AWCNF2787 Station (water company) Gallow Brook
Yelling high Pumping Station on D44 Street Pumping Sewerage Network AWCNF2374 Station (water company) Tributary of West Brook
WwTW/Sewage D45 Hail Weston Treatment Works (water AWCNF1285 STW company) River Kym
Pollution Incidents The Environment Agency provided data on known pollution incidents within 2 kilometres (1.2 miles) of the Scheme in May 2019. During the period 2013-2019, there were 23 pollution incidents of Category 3 (minor) relating to the water environment and listed in Table A3 along with the receiving watercourses.
Planning Inspectorate Scheme Ref: TR010044 8 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Table A3: Known pollution incidents within 2 kilometres (1.2 miles) of the Scheme (Source: EA)
Probable Figure Notificati Cause of NGR Pollutant Receiving 13.1 Ref. on ID incident waters
P1 1102821 TL 287 624 Oils and Fuel Vandalism Ditch upstream of West Brook
P2 1329084 TL 278 604 Oils and Fuel Road Traffic Ditch (diesel) Accident (RTA) upstream of West Brook
P3 1419815 TL 162 537 Sewage Materials Sewer Failure or Tributary (crude sewage) Overflow immediately upstream of River Great Ouse
P4 1117088 TL 162 537 Sewage Materials Unauthorised Ditch (crude sewage) Discharge or upstream of Disposal River Great Ouse
P5 1368452 TL 154 541 Sewage Materials Abnormal Ditch (final effluent) Process upstream of Operation River Great Ouse
P6 1466405 TL 167 545 Sewage Materials Other Stone Brook (final effluent)
P7 1465101 TL 164 561 Sewage Materials Control Measure Ditch (final effluent) Failure upstream of Begwary Brook
P8 1542815 TL 164 562 Oils and Fuel Other Fire Begwary Brook
P9 1146018 TL 183 566 General Algal Activity Ditch Biodegradable upstream of Materials and River Great Wastes (algae) Ouse
P10 1515310 TL 184 576 Inorganic Control Measure River Great Chemicals/Product Failure Ouse s
P11 1351786 TL 154 541 Sewage Materials Septic Tank or Ditch (crude sewage) Sewage upstream of
Planning Inspectorate Scheme Ref: TR010044 9 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Probable Figure Notificati Cause of NGR Pollutant Receiving 13.1 Ref. on ID incident waters Treatment Plant River Great Failure Ouse
P12 1455747 TL 154 541 Sewage Materials Abnormal Ditch (final effluent) Process upstream of Operation River Great Ouse
P13 1368452 TL154 541 Sewage Materials Abnormal Ditch (final effluent) Process upstream of Operation River Great Ouse
P14 1376046 TL167 581 Specific Waste Unauthorised Ditch Materials Discharge or upstream of Disposal River Great Ouse
P15 1437224 TL167 584 Oils and Fuel Other Fire Ditch upstream of River Great Ouse
P16 1282433 TL173 586 Sewage Materials Sewer Failure or Ditch Overflow upstream of River Great Ouse
P17 1490530 TL173 586 Sewage Materials Sewer Failure or Ditch Overflow upstream of River Great Ouse
P18 1556550 TL175 586 Organic Not Identified River Great Chemicals/Product Ouse s
P19 1473981 TL188 591 Contaminated Other Fire Drain Water upstream of Hen Brook
P20 1480208 TL188 594 Sewage Materials Control System Drain Failure upstream of Hen Brook
P21 1344910 TL192 602 Pollutant Not Not Identified Drain Identified upstream of Fox Brook
Planning Inspectorate Scheme Ref: TR010044 10 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Probable Figure Notificati Cause of NGR Pollutant Receiving 13.1 Ref. on ID incident waters
P22 1347039 TL192 602 Pollutant Not Not Identified Drain Identified upstream of Fox Brook
P23 1329084 TL278 604 Oils and Fuel Road Traffic Ditches Accident (RTA) upstream of West Brook
The causes of the pollution incidents detailed in Table A3 range from road traffic accidents causing oil and fuel spillage adjacent to the A428, to crude sewage and final effluent pollution incidents. All of the incidents are categorised as minor, so are not expected to have had long term consequences to the receiving watercourses.
Planning Inspectorate Scheme Ref: TR010044 11 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
4 Summary of geology, hydrogeology and soils Geological data for the study area were obtained from the BGS online GeoIndex Viewer (Ref 13-43). The west of the study area (approximately west of Toseland Road between the villages of Weald/Croxton) is underlain by the bedrock of the Oxford Clay Formation and the Peterborough Member, while the east is underlain by the West Walton Formation and Ampthill Clay Formation (undifferentiated), and the Kimmeridge Clay Formation. These deposits of Jurassic origin consist of mudstone, siltstone and sandstone. To the south of the study area are the Cretaceous sandstone and mudstone deposits of the Lower Greensand Group. The Oxford Clay and the West Walton Formation are designated as unproductive strata. Superficial geology within the study area is dominated by the glacial diamicton of the Oadby Member, with alluvium and river terrace deposits surrounding the River Great Ouse and other smaller rivers. There are also small outcrops of glaciofluvial deposits located in the central and eastern parts of the study area of the Scheme. To the east of St Neots along the existing A428 towards Hen Brook, there is little or no superficial deposits other than along Hen Brook and the B1046. The glacial diamicton deposits are designated as unproductive aquifers, whereas the alluvium and river terrace deposits are designated Secondary A aquifers. Soil data for the study area were obtained from Cranfield University’s Soilscapes website (Ref 13-44). Soils within the study area largely consist of lime-rich loamy and clayey soils with impeded drainage. Surrounding the River Great Ouse are loamy and clayey floodplain soils with naturally high groundwater, and freely draining and slightly acid loamy soils. These correspond to areas of alluvial and river terrace deposits. Loamy soils can be readily eroded by water when they are exposed and vegetation removed, as can clay rich soils, especially when they dry out and become more friable.
Planning Inspectorate Scheme Ref: TR010044 12 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
5 Details on key watercourses 5.1 River Great Ouse The River Great Ouse is a large, lowland passively meandering single thread watercourse and flows in a south-west to north-easterly direction through the study area. The channel is approximately 20m wide at the proposed crossing location. The majority of the other key watercourses listed in Table 13-4 (except Bourn Brook) are tributaries of the River Great Ouse. According to the National River Flow Archive (Ref 13-71) there is a gauging station (Station 33039) on the River Great Ouse at Roxton, just upstream of St Neots and around 2 kilometres (1.2 miles) from the Scheme (TL 216 669). The gauging station was opened in 1972 and the catchment area upstream is approximately 1,660 kilometres2 (1031.5 miles2). According to the station information, the catchment regime is influenced by surface and groundwater abstraction/ recharge (for PWS, industry and agriculture) and some effluent returns. The data for this monitoring station has a Q95 flow (flow that is exceeded 95% of the time) of 2.19 m3/s. The Bedford Ouse is joined a short distance downstream by the River Ivel, thus increasing the flow significantly by the time the River Great Ouse reaches the existing Black Cat roundabout. The River Great Ouse is a Main River and designated under the WFD as ‘Ouse (Roxton to Earith)’ (GB105033047921) (Ref 13-45). The watercourse is designated from the confluence of the River Great Ouse and River Ivel near Roxton, to Earith where it becomes the Great Ouse transitional water body. It is designated as a heavily modified waterbody and is currently at Moderate Ecological Potential but failing to meet Good chemical status (2019) (Ref 13-45). The reasons for not achieving Good Ecological Potential are: a. Physical modification for recreation and flood protection impacting mitigation measures assessment. b. Point source pollution from continuous sewage discharge related to waste water treatment impacting phosphate. c. Diffuse source pollution from poor nutrient management relating to arable agriculture impacting phosphate. d. Diffuse source pollution from poor livestock management impacting phosphate. The River Great Ouse is failing to meet Good chemical status due to priority substances (Polybrominated diphenyl ethers (PBDE) and Perfluoro-octane sulphonate (PFOS)). During a review of baseline information, the only known socio-economic uses of the watercourses would be the navigational use of the River Great Ouse. There is a marina adjacent to the A1 with riverside moorings where the A1 crosses the River Great Ouse. The known fishing uses are located on specialist ponds/ fisheries and not on the watercourses themselves.
Planning Inspectorate Scheme Ref: TR010044 13 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
5.2 Rockham Ditch Rockham Ditch is an ordinary watercourse which flows from its source located to the west of Roxton to its confluence with the River Great Ouse to the west of the existing Black Cat roundabout (refer to Figure 13.1 of the Environmental Statement [TR010044/APP/6.2]). Rockham Ditch was observed in four locations (downstream of its culverted crossings under the A421 and Bedford Rod, near to the Roxton Garden Centre, and downstream of the A1 towards its confluence with the River Great Ouse) during a site visit in November 2017 (NGR: TL 15345 55268 to TL 16311 54897). Between the A421 and A1 the watercourse was approximately 1m wide and incised with steep banks rising 2-3m in height to the surrounding fields. The watercourse is artificially straight. Water depth at the time of the site visit was 2- 3cm. There was a small amount of gravel (2-3cm diameter) and some accumulations of fine sediment in the channel. The ditch was largely overgrown with vegetation including brambles and nettles. The channel was much larger upstream of the Bedford Road culvert, being around 3m wide and 20cm deep. This suggests that flow is being impeded by the culvert leading to pooling upstream. The watercourse was also visited between the large culvert beneath the A1 on the periphery of the Black Cat Quarry and its confluence with the River Great Ouse (around 500m downstream of the large culvert). The A1 culvert was a circular, concrete culvert of around 1.5 metre in diameter. There was very little distinguishable flow through the culvert and it was full of fine sediment, with a significant amount of emergent macrophyte vegetation growing in the channel immediately downstream. Using Wallingford Hydrosolutions Ltd LowFlows software at a point within the watercourse in the area of the existing Black Cat roundabout, there is an estimated flow of 0.002 m3/s. The LowFlow Data for flows within Rockham Ditch are included in Table A4 below.
Planning Inspectorate Scheme Ref: TR010044 14 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Table A4: LowFlows data for Rockham Ditch in (m3/s)
Annual Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Q mean 0.01 0.023 0.02 0.017 0.011 0.007 0.004 0.003 0.003 0.003 0.007 0.011 0.016
Q(0.1) 0.237 0.141 0.199 0.131 0.117 0.123 0.071 0.038 0.085 0.102 0.254 0.172 0.154
Q(1) 0.098 0.111 0.106 0.091 0.06 0.045 0.02 0.012 0.015 0.018 0.08 0.088 0.098
Q(2) 0.068 0.095 0.082 0.075 0.048 0.026 0.012 0.008 0.009 0.012 0.05 0.068 0.073
Q(3) 0.054 0.077 0.067 0.065 0.041 0.02 0.01 0.007 0.007 0.01 0.032 0.059 0.062
Q(4) 0.045 0.07 0.063 0.056 0.037 0.017 0.009 0.006 0.006 0.008 0.025 0.052 0.055
Q(5) 0.038 0.064 0.057 0.049 0.033 0.014 0.008 0.005 0.005 0.007 0.021 0.043 0.051
Q(6) 0.033 0.058 0.054 0.045 0.03 0.013 0.007 0.005 0.005 0.006 0.018 0.039 0.046
Q(7) 0.03 0.055 0.047 0.04 0.027 0.011 0.007 0.005 0.005 0.005 0.015 0.034 0.042
Q(8) 0.026 0.053 0.044 0.036 0.025 0.011 0.006 0.004 0.004 0.005 0.014 0.03 0.039
Q(9) 0.024 0.05 0.041 0.033 0.024 0.01 0.006 0.004 0.004 0.005 0.012 0.026 0.035
Planning Inspectorate Scheme Ref: TR010044 15 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Annual Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Q(10) 0.022 0.047 0.038 0.031 0.022 0.01 0.006 0.004 0.004 0.004 0.011 0.024 0.033
Q(11) 0.02 0.044 0.036 0.029 0.021 0.009 0.005 0.004 0.004 0.004 0.01 0.022 0.031
Q(12) 0.018 0.042 0.034 0.028 0.02 0.009 0.005 0.004 0.004 0.004 0.009 0.019 0.03
Q(13) 0.017 0.04 0.032 0.026 0.018 0.008 0.005 0.004 0.003 0.004 0.009 0.018 0.028
Q(14) 0.016 0.037 0.031 0.025 0.017 0.008 0.005 0.004 0.003 0.004 0.008 0.016 0.027
Q(15) 0.015 0.036 0.029 0.023 0.017 0.008 0.005 0.004 0.003 0.004 0.008 0.015 0.025
Q(16) 0.014 0.035 0.028 0.022 0.016 0.008 0.005 0.003 0.003 0.003 0.007 0.014 0.024
Q(17) 0.013 0.034 0.027 0.021 0.015 0.007 0.005 0.003 0.003 0.003 0.007 0.013 0.023
Q(18) 0.012 0.032 0.026 0.02 0.014 0.007 0.005 0.003 0.003 0.003 0.007 0.012 0.022
Q(19) 0.012 0.03 0.024 0.019 0.014 0.007 0.004 0.003 0.003 0.003 0.006 0.011 0.021
Q(20) 0.011 0.029 0.023 0.018 0.013 0.007 0.004 0.003 0.003 0.003 0.006 0.01 0.02
Planning Inspectorate Scheme Ref: TR010044 16 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Annual Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Q(21) 0.011 0.028 0.023 0.017 0.012 0.007 0.004 0.003 0.003 0.003 0.006 0.01 0.019
Q(22) 0.01 0.027 0.022 0.017 0.012 0.007 0.004 0.003 0.003 0.003 0.005 0.009 0.018
Q(23) 0.01 0.026 0.021 0.016 0.011 0.006 0.004 0.003 0.003 0.003 0.005 0.009 0.017
Q(24) 0.009 0.025 0.02 0.016 0.011 0.006 0.004 0.003 0.003 0.003 0.005 0.008 0.016
Q(25) 0.009 0.024 0.019 0.015 0.011 0.006 0.004 0.003 0.003 0.003 0.005 0.008 0.016
Q(26) 0.009 0.023 0.019 0.015 0.01 0.006 0.004 0.003 0.003 0.003 0.005 0.008 0.015
Q(27) 0.008 0.023 0.018 0.014 0.01 0.006 0.004 0.003 0.003 0.003 0.004 0.007 0.015
Q(28) 0.008 0.022 0.018 0.014 0.01 0.006 0.004 0.003 0.003 0.003 0.004 0.007 0.014
Q(29) 0.008 0.021 0.017 0.014 0.01 0.006 0.004 0.003 0.003 0.003 0.004 0.007 0.014
Q(30) 0.008 0.021 0.017 0.013 0.009 0.006 0.004 0.003 0.003 0.003 0.004 0.007 0.013
Q(31) 0.007 0.02 0.016 0.013 0.009 0.006 0.004 0.003 0.003 0.003 0.004 0.006 0.013
Planning Inspectorate Scheme Ref: TR010044 17 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Annual Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Q(32) 0.007 0.019 0.016 0.013 0.009 0.006 0.004 0.003 0.003 0.003 0.004 0.006 0.013
Q(33) 0.007 0.019 0.016 0.012 0.009 0.005 0.004 0.003 0.003 0.003 0.004 0.006 0.012
Q(34) 0.007 0.018 0.015 0.012 0.008 0.005 0.004 0.003 0.003 0.003 0.004 0.006 0.012
Q(35) 0.007 0.017 0.015 0.012 0.008 0.005 0.004 0.003 0.003 0.003 0.004 0.006 0.011
Q(36) 0.006 0.017 0.014 0.012 0.008 0.005 0.004 0.003 0.003 0.003 0.003 0.006 0.011
Q(37) 0.006 0.017 0.014 0.011 0.008 0.005 0.003 0.003 0.002 0.003 0.003 0.005 0.011
Q(38) 0.006 0.016 0.014 0.011 0.008 0.005 0.003 0.003 0.002 0.002 0.003 0.005 0.01
Q(39) 0.006 0.016 0.013 0.011 0.008 0.005 0.003 0.003 0.002 0.002 0.003 0.005 0.01
Q(40) 0.006 0.015 0.013 0.011 0.008 0.005 0.003 0.003 0.002 0.002 0.003 0.005 0.01
Q(41) 0.005 0.015 0.013 0.01 0.008 0.005 0.003 0.003 0.002 0.002 0.003 0.005 0.01
Q(42) 0.005 0.014 0.012 0.01 0.007 0.005 0.003 0.003 0.002 0.002 0.003 0.005 0.009
Planning Inspectorate Scheme Ref: TR010044 18 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Annual Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Q(43) 0.005 0.014 0.012 0.01 0.007 0.005 0.003 0.003 0.002 0.002 0.003 0.005 0.009
Q(44) 0.005 0.013 0.012 0.01 0.007 0.005 0.003 0.003 0.002 0.002 0.003 0.005 0.009
Q(45) 0.005 0.013 0.012 0.01 0.007 0.005 0.003 0.003 0.002 0.002 0.003 0.005 0.009
Q(46) 0.005 0.013 0.011 0.01 0.007 0.005 0.003 0.002 0.002 0.002 0.003 0.004 0.009
Q(47) 0.005 0.012 0.011 0.01 0.007 0.005 0.003 0.002 0.002 0.002 0.003 0.004 0.008
Q(48) 0.005 0.012 0.011 0.009 0.007 0.004 0.003 0.002 0.002 0.002 0.003 0.004 0.008
Q(49) 0.004 0.012 0.011 0.009 0.007 0.004 0.003 0.002 0.002 0.002 0.003 0.004 0.008
Q(50) 0.004 0.011 0.011 0.009 0.007 0.004 0.003 0.002 0.002 0.002 0.003 0.004 0.008
Q(51) 0.004 0.011 0.01 0.009 0.007 0.004 0.003 0.002 0.002 0.002 0.003 0.004 0.008
Q(52) 0.004 0.011 0.01 0.009 0.006 0.004 0.003 0.002 0.002 0.002 0.003 0.004 0.008
Q(53) 0.004 0.011 0.01 0.009 0.006 0.004 0.003 0.002 0.002 0.002 0.003 0.004 0.007
Planning Inspectorate Scheme Ref: TR010044 19 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Annual Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Q(54) 0.004 0.01 0.01 0.009 0.006 0.004 0.003 0.002 0.002 0.002 0.003 0.004 0.007
Q(55) 0.004 0.01 0.01 0.008 0.006 0.004 0.003 0.002 0.002 0.002 0.003 0.004 0.007
Q(56) 0.004 0.01 0.009 0.008 0.006 0.004 0.003 0.002 0.002 0.002 0.003 0.004 0.007
Q(57) 0.004 0.009 0.009 0.008 0.006 0.004 0.003 0.002 0.002 0.002 0.003 0.004 0.007
Q(58) 0.004 0.009 0.009 0.008 0.006 0.004 0.003 0.002 0.002 0.002 0.003 0.004 0.007
Q(59) 0.003 0.009 0.009 0.008 0.006 0.004 0.003 0.002 0.002 0.002 0.003 0.004 0.006
Q(60) 0.003 0.009 0.009 0.008 0.006 0.004 0.003 0.002 0.002 0.002 0.003 0.004 0.006
Q(61) 0.003 0.009 0.009 0.008 0.006 0.004 0.003 0.002 0.002 0.002 0.003 0.004 0.006
Q(62) 0.003 0.008 0.008 0.008 0.006 0.004 0.003 0.002 0.002 0.002 0.002 0.003 0.006
Q(63) 0.003 0.008 0.008 0.007 0.006 0.004 0.003 0.002 0.002 0.002 0.002 0.003 0.006
Q(64) 0.003 0.008 0.008 0.007 0.006 0.004 0.003 0.002 0.002 0.002 0.002 0.003 0.006
Planning Inspectorate Scheme Ref: TR010044 20 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Annual Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Q(65) 0.003 0.008 0.008 0.007 0.005 0.004 0.003 0.002 0.002 0.002 0.002 0.003 0.006
Q(66) 0.003 0.008 0.008 0.007 0.005 0.004 0.003 0.002 0.002 0.002 0.002 0.003 0.006
Q(67) 0.003 0.007 0.008 0.007 0.005 0.004 0.003 0.002 0.002 0.002 0.002 0.003 0.005
Q(68) 0.003 0.007 0.007 0.007 0.005 0.004 0.003 0.002 0.002 0.002 0.002 0.003 0.005
Q(69) 0.003 0.007 0.007 0.007 0.005 0.004 0.003 0.002 0.002 0.002 0.002 0.003 0.005
Q(70) 0.003 0.007 0.007 0.007 0.005 0.004 0.003 0.002 0.002 0.002 0.002 0.003 0.005
Q(71) 0.003 0.007 0.007 0.007 0.005 0.003 0.003 0.002 0.002 0.002 0.002 0.003 0.005
Q(72) 0.003 0.007 0.007 0.006 0.005 0.003 0.003 0.002 0.002 0.002 0.002 0.003 0.005
Q(73) 0.003 0.006 0.007 0.006 0.005 0.003 0.003 0.002 0.002 0.002 0.002 0.003 0.005
Q(74) 0.003 0.006 0.007 0.006 0.005 0.003 0.003 0.002 0.002 0.002 0.002 0.003 0.005
Q(75) 0.003 0.006 0.007 0.006 0.005 0.003 0.002 0.002 0.002 0.002 0.002 0.003 0.004
Planning Inspectorate Scheme Ref: TR010044 21 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Annual Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Q(76) 0.003 0.006 0.006 0.006 0.005 0.003 0.002 0.002 0.002 0.002 0.002 0.003 0.004
Q(77) 0.003 0.006 0.006 0.006 0.005 0.003 0.002 0.002 0.002 0.002 0.002 0.003 0.004
Q(78) 0.002 0.006 0.006 0.006 0.005 0.003 0.002 0.002 0.002 0.002 0.002 0.003 0.004
Q(79) 0.002 0.006 0.006 0.006 0.004 0.003 0.002 0.002 0.002 0.002 0.002 0.003 0.004
Q(80) 0.002 0.006 0.006 0.006 0.004 0.003 0.002 0.002 0.002 0.002 0.002 0.003 0.004
Q(81) 0.002 0.005 0.005 0.005 0.004 0.003 0.002 0.002 0.002 0.002 0.002 0.003 0.004
Q(82) 0.002 0.005 0.005 0.005 0.004 0.003 0.002 0.002 0.002 0.002 0.002 0.003 0.004
Q(83) 0.002 0.005 0.005 0.005 0.004 0.003 0.002 0.002 0.002 0.002 0.002 0.003 0.004
Q(84) 0.002 0.005 0.005 0.005 0.004 0.003 0.002 0.002 0.002 0.002 0.002 0.003 0.004
Q(85) 0.002 0.005 0.005 0.005 0.004 0.003 0.002 0.002 0.002 0.002 0.002 0.003 0.004
Q(86) 0.002 0.005 0.005 0.005 0.004 0.003 0.002 0.002 0.002 0.002 0.002 0.003 0.004
Planning Inspectorate Scheme Ref: TR010044 22 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Annual Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Q(87) 0.002 0.004 0.004 0.005 0.004 0.003 0.002 0.002 0.002 0.002 0.002 0.003 0.003
Q(88) 0.002 0.004 0.004 0.005 0.004 0.003 0.002 0.002 0.001 0.002 0.002 0.003 0.003
Q(89) 0.002 0.004 0.004 0.004 0.003 0.003 0.002 0.002 0.001 0.002 0.002 0.003 0.003
Q(90) 0.002 0.004 0.004 0.004 0.003 0.003 0.002 0.002 0.001 0.002 0.002 0.003 0.003
Q(91) 0.002 0.004 0.004 0.004 0.003 0.003 0.002 0.001 0.001 0.002 0.002 0.003 0.003
Q(92) 0.002 0.004 0.004 0.004 0.003 0.002 0.002 0.001 0.001 0.002 0.002 0.002 0.003
Q(93) 0.002 0.004 0.004 0.004 0.003 0.002 0.002 0.001 0.001 0.001 0.002 0.002 0.003
Q(94) 0.002 0.004 0.004 0.003 0.003 0.002 0.002 0.001 0.001 0.001 0.002 0.002 0.003
Q(95) 0.002 0.003 0.003 0.003 0.003 0.002 0.002 0.001 0.001 0.001 0.002 0.002 0.003
Q(96) 0.002 0.003 0.003 0.003 0.003 0.002 0.001 0.001 0.001 0.001 0.002 0.002 0.003
Q(97) 0.001 0.003 0.003 0.003 0.003 0.002 0.001 0.001 0.001 0.001 0.002 0.002 0.003
Planning Inspectorate Scheme Ref: TR010044 23 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Annual Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Q(98) 0.001 0.003 0.003 0.003 0.002 0.002 0.001 0.001 0.001 0.001 0.002 0.002 0.003
Q(99) 0.001 0.003 0.003 0.003 0.002 0.002 0.001 0.001 0.001 0.001 0.001 0.002 0.003
Q(99.9) 0.001 0.002 0.003 0.002 0.002 0.002 0.001 0.001 0.001 0.001 0.001 0.002 0.002
Planning Inspectorate Scheme Ref: TR010044 24 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
5.3 South Brook South Brook is an ordinary watercourse which is formed from the coalescence of various ditches between Roxton and Wilden. It flows towards the north-east to its confluence with the River Great Ouse (refer to Figure 13.1 of the Environmental Statement [TR010044/APP/6.2] to the north of the existing Black Cat roundabout). South Brook was observed to the east of the existing A1 crossing and at Chawston in November 2017 (between NGR TL 16307 55786 and TL 15320 55962). It flows beneath the A1 through a box culvert approximately 50m long and 3 metre wide. Immediately downstream of the culvert the watercourse is 5-6 metres wide but narrows to 4 metres further on. It has a section of solid concrete bed at this location, is artificially straightened, shows evidence of dredging and is incised with steep banks of up to 2 metres to the surrounding land, resulting in poor floodplain connectivity. There is a significant amount of emergent macrophyte vegetation. There are road outfalls entering the stream here from the A1. There was a small amount of gravel visible on the bed, and little fine sediment. Around 100m downstream of the A1 culvert the channel narrows to 2.5-3 metres in width. It remains an overwide channel but with narrower reaches leading to some patches of faster flow, with flow otherwise generally being extremely slow under normal flow conditions. Using Wallingford Hydrosolutions Ltd LowFlows software at a point within the watercourse downstream of the Scheme, there is an estimated flow of 0.014 m3/s. The LowFlow Data for flows within South Brook are included in Table A5 below.
Planning Inspectorate Scheme Ref: TR010044 25 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Table A5: LowFlows data for South Brook (in m3/s)
Annual Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Qmean 0.102 0.221 0.191 0.167 0.114 0.07 0.041 0.028 0.029 0.032 0.069 0.108 0.163
Q(0.1) 2.266 1.387 2.412 1.295 1.107 1.221 0.818 0.553 1.021 1.159 1.919 1.505 1.668
Q(1) 0.981 1.061 0.986 0.919 0.656 0.571 0.34 0.163 0.218 0.261 0.84 0.864 0.951
Q(2) 0.707 0.891 0.797 0.778 0.513 0.318 0.199 0.113 0.131 0.174 0.521 0.726 0.742
Q(3) 0.568 0.759 0.711 0.682 0.445 0.257 0.156 0.084 0.099 0.125 0.373 0.621 0.669
Q(4) 0.476 0.696 0.632 0.6 0.395 0.224 0.129 0.074 0.083 0.104 0.273 0.506 0.58
Q(5) 0.401 0.643 0.59 0.499 0.347 0.177 0.109 0.066 0.071 0.092 0.236 0.415 0.529
Q(6) 0.351 0.61 0.545 0.466 0.324 0.157 0.096 0.058 0.064 0.081 0.196 0.365 0.486
Q(7) 0.313 0.562 0.48 0.421 0.295 0.142 0.084 0.054 0.057 0.067 0.173 0.321 0.439
Q(8) 0.279 0.537 0.452 0.381 0.279 0.129 0.075 0.05 0.053 0.059 0.154 0.284 0.41
Q(9) 0.255 0.492 0.427 0.35 0.266 0.119 0.07 0.048 0.048 0.054 0.139 0.246 0.386
Planning Inspectorate Scheme Ref: TR010044 26 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Annual Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Q(10) 0.234 0.473 0.399 0.33 0.251 0.113 0.064 0.046 0.045 0.05 0.125 0.226 0.354
Q(11) 0.215 0.459 0.377 0.306 0.234 0.107 0.059 0.044 0.042 0.045 0.114 0.206 0.336
Q(12) 0.197 0.433 0.361 0.292 0.22 0.101 0.056 0.042 0.039 0.043 0.103 0.187 0.315
Q(13) 0.182 0.404 0.333 0.282 0.208 0.097 0.054 0.041 0.037 0.04 0.093 0.168 0.3
Q(14) 0.17 0.39 0.309 0.264 0.195 0.093 0.051 0.039 0.036 0.037 0.088 0.157 0.277
Q(15) 0.158 0.369 0.298 0.249 0.185 0.09 0.048 0.037 0.034 0.035 0.082 0.147 0.263
Q(16) 0.148 0.357 0.287 0.239 0.175 0.088 0.047 0.035 0.033 0.033 0.077 0.134 0.253
Q(17) 0.139 0.343 0.271 0.223 0.167 0.084 0.045 0.035 0.032 0.032 0.072 0.124 0.241
Q(18) 0.13 0.327 0.255 0.214 0.158 0.081 0.044 0.034 0.031 0.031 0.069 0.116 0.231
Q(19) 0.123 0.312 0.244 0.203 0.151 0.079 0.043 0.033 0.03 0.029 0.064 0.108 0.221
Q(20) 0.116 0.303 0.237 0.194 0.144 0.075 0.042 0.033 0.029 0.028 0.059 0.1 0.212
Planning Inspectorate Scheme Ref: TR010044 27 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Annual Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Q(21) 0.11 0.289 0.229 0.184 0.135 0.073 0.041 0.032 0.028 0.027 0.056 0.095 0.202
Q(22) 0.105 0.275 0.216 0.179 0.128 0.071 0.04 0.031 0.028 0.027 0.052 0.09 0.192
Q(23) 0.1 0.268 0.209 0.172 0.122 0.07 0.039 0.03 0.027 0.026 0.049 0.086 0.183
Q(24) 0.096 0.259 0.2 0.166 0.117 0.068 0.038 0.03 0.027 0.025 0.047 0.082 0.178
Q(25) 0.091 0.248 0.191 0.162 0.112 0.065 0.037 0.029 0.026 0.024 0.045 0.079 0.169
Q(26) 0.088 0.242 0.189 0.155 0.109 0.063 0.036 0.028 0.026 0.024 0.042 0.076 0.161
Q(27) 0.085 0.232 0.182 0.15 0.105 0.062 0.036 0.028 0.025 0.024 0.041 0.072 0.152
Q(28) 0.081 0.228 0.18 0.145 0.103 0.061 0.035 0.028 0.024 0.023 0.039 0.069 0.148
Q(29) 0.078 0.217 0.17 0.14 0.1 0.059 0.035 0.027 0.024 0.023 0.038 0.067 0.142
Q(30) 0.075 0.211 0.164 0.137 0.097 0.056 0.034 0.027 0.023 0.022 0.036 0.065 0.14
Q(31) 0.073 0.205 0.16 0.133 0.092 0.055 0.034 0.026 0.023 0.022 0.035 0.063 0.134
Planning Inspectorate Scheme Ref: TR010044 28 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Annual Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Q(32) 0.071 0.197 0.153 0.13 0.089 0.055 0.033 0.026 0.023 0.022 0.034 0.06 0.128
Q(33) 0.068 0.19 0.149 0.126 0.087 0.053 0.033 0.026 0.022 0.022 0.032 0.057 0.121
Q(34) 0.066 0.188 0.146 0.123 0.085 0.052 0.032 0.025 0.022 0.021 0.031 0.054 0.118
Q(35) 0.064 0.181 0.143 0.12 0.082 0.051 0.032 0.025 0.022 0.021 0.03 0.051 0.114
Q(36) 0.062 0.176 0.138 0.116 0.08 0.05 0.032 0.024 0.021 0.021 0.029 0.049 0.11
Q(37) 0.059 0.171 0.136 0.111 0.079 0.047 0.031 0.024 0.021 0.021 0.028 0.047 0.107
Q(38) 0.057 0.165 0.131 0.108 0.078 0.046 0.031 0.024 0.021 0.021 0.027 0.046 0.104
Q(39) 0.055 0.159 0.127 0.107 0.076 0.046 0.031 0.024 0.021 0.02 0.027 0.045 0.102
Q(40) 0.054 0.151 0.123 0.105 0.075 0.045 0.03 0.023 0.021 0.02 0.026 0.043 0.098
Q(41) 0.052 0.147 0.121 0.101 0.074 0.044 0.029 0.023 0.021 0.02 0.026 0.042 0.096
Q(42) 0.05 0.145 0.118 0.099 0.072 0.044 0.029 0.023 0.02 0.02 0.025 0.041 0.094
Planning Inspectorate Scheme Ref: TR010044 29 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Annual Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Q(43) 0.048 0.141 0.115 0.098 0.072 0.043 0.029 0.022 0.02 0.02 0.025 0.04 0.091
Q(44) 0.046 0.137 0.111 0.096 0.07 0.042 0.028 0.022 0.02 0.019 0.024 0.039 0.089
Q(45) 0.045 0.132 0.108 0.094 0.068 0.041 0.028 0.022 0.02 0.019 0.023 0.037 0.087
Q(46) 0.044 0.127 0.106 0.092 0.067 0.04 0.028 0.022 0.02 0.019 0.023 0.037 0.085
Q(47) 0.042 0.124 0.105 0.09 0.066 0.039 0.027 0.022 0.019 0.019 0.022 0.036 0.082
Q(48) 0.041 0.12 0.103 0.089 0.065 0.038 0.027 0.021 0.019 0.019 0.022 0.035 0.08
Q(49) 0.039 0.117 0.1 0.087 0.064 0.038 0.027 0.021 0.019 0.019 0.022 0.035 0.078
Q(50) 0.038 0.112 0.098 0.086 0.063 0.037 0.026 0.021 0.019 0.019 0.022 0.034 0.077
Q(51) 0.037 0.11 0.095 0.084 0.062 0.036 0.026 0.021 0.019 0.018 0.022 0.034 0.075
Q(52) 0.036 0.106 0.093 0.081 0.061 0.036 0.026 0.021 0.018 0.018 0.021 0.033 0.073
Q(53) 0.035 0.102 0.091 0.08 0.059 0.036 0.025 0.021 0.018 0.018 0.021 0.032 0.071
Planning Inspectorate Scheme Ref: TR010044 30 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Annual Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Q(54) 0.034 0.099 0.091 0.079 0.058 0.035 0.025 0.021 0.018 0.018 0.021 0.032 0.07
Q(55) 0.033 0.097 0.088 0.077 0.057 0.035 0.025 0.02 0.018 0.018 0.021 0.031 0.068
Q(56) 0.032 0.095 0.086 0.076 0.057 0.034 0.025 0.02 0.018 0.018 0.02 0.031 0.066
Q(57) 0.032 0.09 0.085 0.075 0.056 0.034 0.024 0.02 0.018 0.018 0.02 0.03 0.065
Q(58) 0.031 0.088 0.083 0.074 0.055 0.034 0.024 0.02 0.018 0.018 0.02 0.03 0.063
Q(59) 0.03 0.086 0.081 0.073 0.053 0.033 0.024 0.02 0.017 0.017 0.02 0.029 0.061
Q(60) 0.029 0.083 0.08 0.072 0.052 0.033 0.023 0.02 0.017 0.017 0.02 0.029 0.06
Q(61) 0.028 0.08 0.078 0.071 0.052 0.032 0.023 0.019 0.017 0.017 0.02 0.028 0.058
Q(62) 0.028 0.078 0.077 0.069 0.05 0.032 0.023 0.019 0.017 0.017 0.019 0.028 0.057
Q(63) 0.027 0.074 0.076 0.068 0.049 0.031 0.023 0.019 0.017 0.017 0.019 0.028 0.055
Q(64) 0.027 0.073 0.074 0.067 0.049 0.031 0.022 0.019 0.017 0.017 0.019 0.027 0.054
Planning Inspectorate Scheme Ref: TR010044 31 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Annual Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Q(65) 0.026 0.072 0.073 0.066 0.048 0.03 0.022 0.019 0.017 0.017 0.019 0.027 0.052
Q(66) 0.026 0.072 0.071 0.065 0.046 0.03 0.022 0.018 0.016 0.017 0.018 0.027 0.051
Q(67) 0.025 0.07 0.069 0.064 0.045 0.029 0.022 0.018 0.016 0.017 0.018 0.026 0.05
Q(68) 0.024 0.067 0.068 0.062 0.044 0.029 0.021 0.018 0.016 0.016 0.018 0.026 0.049
Q(69) 0.024 0.065 0.066 0.061 0.043 0.029 0.021 0.018 0.016 0.016 0.018 0.025 0.047
Q(70) 0.023 0.063 0.065 0.06 0.042 0.028 0.021 0.018 0.016 0.016 0.018 0.025 0.046
Q(71) 0.023 0.062 0.064 0.057 0.041 0.028 0.021 0.017 0.016 0.016 0.017 0.024 0.044
Q(72) 0.022 0.061 0.063 0.056 0.041 0.028 0.021 0.017 0.016 0.016 0.017 0.024 0.043
Q(73) 0.022 0.06 0.062 0.055 0.04 0.027 0.021 0.017 0.015 0.016 0.017 0.024 0.041
Q(74) 0.022 0.058 0.06 0.054 0.039 0.027 0.021 0.017 0.015 0.016 0.017 0.024 0.04
Q(75) 0.021 0.056 0.058 0.053 0.038 0.027 0.02 0.017 0.015 0.016 0.017 0.023 0.039
Planning Inspectorate Scheme Ref: TR010044 32 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Annual Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Q(76) 0.021 0.055 0.056 0.052 0.037 0.027 0.02 0.016 0.015 0.015 0.017 0.023 0.038
Q(77) 0.021 0.053 0.055 0.05 0.037 0.026 0.02 0.016 0.015 0.015 0.017 0.023 0.036
Q(78) 0.02 0.052 0.054 0.049 0.036 0.026 0.02 0.016 0.015 0.015 0.017 0.022 0.035
Q(79) 0.02 0.051 0.053 0.048 0.036 0.026 0.02 0.016 0.014 0.015 0.016 0.022 0.034
Q(80) 0.02 0.049 0.051 0.046 0.035 0.025 0.019 0.015 0.014 0.015 0.016 0.022 0.034
Q(81) 0.019 0.048 0.05 0.045 0.034 0.025 0.019 0.015 0.014 0.015 0.016 0.022 0.033
Q(82) 0.019 0.047 0.048 0.044 0.034 0.025 0.019 0.015 0.014 0.015 0.016 0.022 0.031
Q(83) 0.019 0.045 0.047 0.043 0.033 0.024 0.018 0.015 0.014 0.015 0.016 0.021 0.03
Q(84) 0.018 0.044 0.046 0.042 0.032 0.024 0.018 0.015 0.014 0.015 0.016 0.021 0.029
Q(85) 0.018 0.042 0.044 0.04 0.031 0.023 0.018 0.014 0.013 0.014 0.016 0.021 0.028
Q(86) 0.017 0.04 0.043 0.038 0.03 0.023 0.017 0.014 0.013 0.014 0.015 0.021 0.028
Planning Inspectorate Scheme Ref: TR010044 33 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Annual Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Q(87) 0.017 0.038 0.041 0.036 0.029 0.022 0.017 0.014 0.013 0.014 0.015 0.02 0.027
Q(88) 0.017 0.036 0.039 0.035 0.028 0.022 0.017 0.013 0.013 0.014 0.015 0.02 0.027
Q(89) 0.016 0.034 0.037 0.035 0.027 0.021 0.016 0.013 0.012 0.014 0.015 0.02 0.026
Q(90) 0.016 0.033 0.036 0.033 0.027 0.021 0.016 0.013 0.012 0.013 0.015 0.02 0.025
Q(91) 0.016 0.031 0.035 0.032 0.025 0.021 0.015 0.013 0.012 0.013 0.015 0.019 0.025
Q(92) 0.015 0.03 0.034 0.03 0.025 0.02 0.015 0.012 0.011 0.012 0.014 0.019 0.024
Q(93) 0.015 0.029 0.032 0.029 0.024 0.019 0.014 0.012 0.011 0.012 0.014 0.019 0.023
Q(94) 0.014 0.028 0.03 0.028 0.023 0.019 0.014 0.011 0.011 0.012 0.014 0.019 0.023
Q(95) 0.014 0.027 0.028 0.028 0.023 0.018 0.014 0.011 0.011 0.012 0.014 0.019 0.021
Q(96) 0.013 0.026 0.027 0.027 0.022 0.018 0.013 0.01 0.01 0.011 0.013 0.018 0.021
Q(97) 0.012 0.025 0.026 0.026 0.021 0.016 0.012 0.01 0.009 0.011 0.013 0.018 0.021
Planning Inspectorate Scheme Ref: TR010044 34 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Annual Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Q(98) 0.011 0.024 0.025 0.024 0.021 0.015 0.012 0.008 0.009 0.011 0.012 0.017 0.02
Q(99) 0.01 0.022 0.023 0.023 0.015 0.013 0.01 0.006 0.007 0.01 0.011 0.016 0.019
Q(99.9) 0.005 0.014 0.021 0.018 0.013 0.01 0.007 0.004 0.005 0.008 0.009 0.013 0.013
Planning Inspectorate Scheme Ref: TR010044 35 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
5.4 Begwary Brook Begwary Brook is an ordinary watercourse and is designated under the Anglian RBMP (Ref 13-45) as ‘Begwary Brook’ (GB105033043230) (Ref 13-45). This is shown on Figure 13.1 of the Environmental Statement [TR010044/APP/6.2] to the north of the existing Black Cat roundabout. The watercourse is designated from its source at Channels End to its confluence with the River Great Ouse. The channel was observed in September 2019 between Roxton Road north of Chawston and Morris Walk south of Wyboston (NGR TL 15061 56662 and TL 15821 56778). Observations of the channel were difficult due to the dense riparian vegetation surrounding the channel. The channel is estimated to be approximately 3 metres wide and incised by around 2 metres deep. The ‘Begwary Brook’ water body is designated as a heavily modified under the WFD and appears to have been straightened and over-deepened. It is currently at Good Ecological Potential but failing to meet Good Chemical Status (2019) (Ref 13-45). The reason for not achieving Good Ecological Potential is due to the invertebrate’s quality element and due to the following pressures and risks: Diffuse source pollution from poor soil management associated with arable agriculture impacting invertebrates. Natural conditions impacting invertebrates. Physical modifications for land drainage impacting invertebrates. Begwary Brook is failing to meet Good chemical status due to priority substances (PBDE and PFOS). Using Wallingford Hydrosolutions Ltd LowFlows software at a point within the watercourse downstream of the Scheme, there is an estimated flow of 0.002 m3/s. 5.5 Stone Brook Stone Brook is an ordinary watercourse and is designated under the Anglian RBMP (Ref 13-45) as ‘Stone Brook’ (GB105033038190) (Ref 13-45). This is shown on Figure 13.1 of the Environmental Statement [TR010044/APP/6.2] to the south-east of the existing Black Cat roundabout. The watercourse is designated from its source, east of Sandy, to its confluence with the River Great Ouse. Tributaries StB2 to StB6 extend northwards from Stone Brook itself to within the Order Limits. Tributary StB1 extends from Barford Road area westwards to Stone Brook.
Planning Inspectorate Scheme Ref: TR010044 36 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Stone Brook was observed from the existing Barford Road (B1043) crossing at Stone Bridge, approximately 200 metres downstream of a sewage treatment works outfall, to its confluence with the River Great Ouse (NGR TL 16716 54541 to TL 16781 55320). The channel appears to have been realigned, straightened, and is over-deep resulting in limited evidence of any bedforms. Flows were very slow, impeded by in channel vegetation, especially upstream and immediately downstream of Stone Bridge, and ponding from the River Great Ouse further downstream (illustrated by the marginal emergent vegetation, rooted floating macrophytes and floating duckweed (lemna sp.). Reeds were abundant at the edges of the channel, contributing to the slow flows. The channel was approximately 1-2 metres wide upstream of the Stone Bridge crossing, and approximately 3-4 metres wide near the confluence with the River Great Ouse. The banks were in excess of 2 metres high, resulting in the brook being disconnected from the floodplain, which is dominated by arable fields. The brook was very turbid indicating an abundance of fine sediment. Himalayan balsam was present in the riparian zone. The ‘Stone Brook’ water body is designated as heavily modified under the WFD. It is currently at Moderate Ecological Potential but failing to meet Good chemical status including invertebrates, ammonia, dissolved oxygen and phosphate levels all not being Good, and not all mitigation measures having been implemented (2019) (Ref 13-45). The reasons for these parameters not being good are due to the following pressures and risks: a. Point source pollution from continuous sewage discharge impacting ammonia, dissolved oxygen, phosphate and invertebrates. b. Diffuse source pollution related to poor nutrient management impacting phosphate and invertebrates. c. Physical modifications for land drainage impacting invertebrates. d. Drought impacting dissolved oxygen. Stone Brook is failing to meet Good chemical status due to priority substances (PBDE and PFOS). Using Wallingford Hydrosolutions Ltd LowFlows software at a point within a tributary to the watercourse downstream of the Scheme, there is an estimated flow of 0.001 m3/s. 5.6 Hen Brook Hen Brook is a Main River and designated under the Anglian RBMP (Ref 13-45) as ‘Abbotsley and Hen Brooks’ (GB105033043240) (Ref 13-45). This is shown on Figure 13.1 of the Environmental Statement [TR010044/APP/6.2] to the south- east of St Neots. The watercourse is designated from its source to the south-west of Great Gransden, where it is named Waresley Dean Brook, to its confluence with the River Great Ouse, where it is named Hen Brook. The watercourse becomes known as Abbotsley Brook downstream of the confluence with Little Brook, eventually becoming Hen Brook downstream of the crossing of Hall Lane. Tributaries to Hen Brook, HB1 to HB4, are located to the south of Hen Brook itself.
Planning Inspectorate Scheme Ref: TR010044 37 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
The channel was observed in November 2017 and again in September 2019 either side of the existing A428 crossing (NGR: TL 20161 58512 to TL 19647 58986). Hen Brook was visited at the existing A428 crossing and at the proposed crossing location which is to the east of the existing crossing. Here the channel was observed to be 2 metres wide and 25cm deep during low flow conditions in 2017. The bed was predominantly covered with fine sediment with some very fine gravel in patches. The channel had steep banks of around 2-3metres up to the adjacent arable fields, giving poor connectivity to the floodplain. Flow is impeded in several places to create ponding. There are some submerged macrophytes and a surface scum indicative of organics. The crossing beneath the existing A428 is a box culvert of around 5 metres width. Flow backs up above the culvert creating a ponded area. Downstream of the culvert an abundance of emergent reed vegetation was found, filtering out fine sediment to some degree. The channel was observed to narrow back to around 2 metres wide and flow increased in this narrower length. During the site visit in 2019, there was little/ no visible flow downstream of the culvert. Himalayan Balsam was seen to be present on the banks. The ‘Abbotsley and Hen Brooks’ water body is designated as heavily modified under the WFD. It is currently at Moderate Ecological Potential but failing to meet Good chemical status (2019) (Ref 13-45). It is at Moderate Ecological Potential due to invertebrates, dissolved oxygen and phosphate quality elements, and because not all mitigation measures have been implemented. Known pressures and risks acting on this water body include: a. Physical modifications for flood protection (impacting mitigation measures assessment, invertebrates and dissolved oxygen), land drainage and urbanisation (impacting mitigation measures assessment and invertebrates). b. Point source pollution from continuous sewage discharge impacting invertebrates, dissolved oxygen and phosphate. c. Diffuse source pollution from poor nutrient management impacting invertebrates, dissolved oxygen and phosphate. d. Flows from land drainage impacting dissolved oxygen. e. Drought impacting dissolved oxygen. Hen Brook is failing to meet Good chemical status due to priority substances (PBDE). Using Wallingford Hydrosolutions Ltd LowFlows software at a point within the watercourse downstream of the Scheme, there is an estimated flow of 0.002 m3/s. 5.7 Wintringham Brook Wintringham Brook is an ordinary watercourse which flows generally in a westerly direction from its source located southeast of Croxton to its confluence with Fox Brook at St Neots. This is shown on Figure 13.1 of the Environmental Statement [TR010044/APP/6.2] to the south-east of St Neots.
Planning Inspectorate Scheme Ref: TR010044 38 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Wintringham Brook was observed to the south-east of the existing A428 crossing (NGR: TL 20920 58977 to TL 20172 59222). The brook has been straightened along field boundaries for agricultural drainage and was noted to be overly deep (approximately 2 metres from bank top) and overly wide (approximately 3 metres). The brook was dry during the site visit in 2019. The channel and banks were found to be heavily vegetated, and there was a buffer strip either side of the watercourse from the arable agricultural land. There is a small piped culverted crossing for farm access close to the proposed crossing point. Further downstream the watercourse is heavily culverted through St Neots towards its confluence with Fox Brook. Using Wallingford Hydrosolutions Ltd LowFlows software at a point within the watercourse downstream of the Scheme, there is an estimated flow of 0.002 m3/s. Further downstream prior to entry into Hen Brook, it is an estimate 0.005 m3/s. Wintringham Brook Tributary extends north and eastwards to the south of the existing Cambridge Road junction. WB1 tributary flows into Wintringham Brook. 5.8 Fox Brook Fox Brook is a Main River which flows from its source located to the east of St Neots, to its confluence with the River Great Ouse (refer to Figure 13.1 of the Environmental Statement [TR010044/APP/6.2] to the east of St Neots). Fox Brook was observed during a site visit in November 2017 and again in September 2019 north of the existing A428 where it would be crossed by the Scheme (NGR: TL 22993 60207 to TL 22711 60340). Three tributaries, labelled FxB1 to FxB3, flow northwards into Fox Brook. Fox Brook rises to the north of Weald (TL 23374 60184), and takes a westerly course towards St Neots, where it discharges into Hen Brook (TL 18557 60060) shortly upstream of the River Great Ouse. Fox Brook is approximately 5.4 kilometres (3.4 miles) long and runs north of the existing A428 where it is proposed to be crossed (approximately TL 22870 60254). Here it is culverted beneath a public bridleway. There was no flow at this location during the initial walkover with the channel consisting of a series of small ponded areas. The channel was noted to be around 1 metre wide and the bed had accumulations of fine sediment. The watercourse is very straight and appears to be highly modified for agricultural drainage. It has deep banks rising around 2 metres from the bed to the adjacent arable fields. The existing culvert beneath the bridleway is around 10 metres length and is a pipe of around 0.5 metre in diameter. 5.9 Gallow Brook Gallow Brook forms from the coalescence of several ditches to the north of Croxton (TL 25499 60457). It flows in a generally westerly direction towards Little Paxton to finally discharge into the River Great Ouse at TL 19504 62323 (refer to Figure 13.1 of the Environmental Statement [TR010044/APP/6.2] to the north- east of St Neots). Gallow Brook is approximately 7.5 kilometres (4.7 miles) long. There is one proposed crossing of Gallow Brook at TL 23716 60694 and a crossing of a tributary (GB3) at approximately TL24810 60740. There are two other tributaries of Gallow Brook, which are referred to as GB1 and GB2, respectively.
Planning Inspectorate Scheme Ref: TR010044 39 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Gallow Brook was observed in November 2017 (and then subsequently for water quality sampling) at the crossing of Toseland Road (NGR: TL 24603 60987 to TL 24243 60937), where it flows beneath the road through a 0.5 metre pipe culvert. There is a downstream pool round 5 metres wide, which then narrows to what is essentially a field drain of around 1m in width as it runs through arable land. The bed is covered with fine sediment. The stream is overgrown and only a small trickle of flow was coming through the culvert during the majority of site visits, while it was dry in August 2018. A road outfall enters the brook through a 0.5 metre pipe downstream of the culvert and a large amount of sediment has accumulated beneath the outfall. The watercourse is ponded in places due to dams created by woody debris, restricting flow when the prevailing conditions are dry. There was poor connectivity to the adjacent fields with banks rising 1.5-2 metres from the watercourse. Using Wallingford Hydrosolutions Ltd LowFlows software at a point within the watercourse downstream of the Scheme, there is an estimated flow of 0.002 m3/s. 5.10 West Brook The study area north of the existing A428 east of Croxton includes the headwaters of the West Brook catchment. These headwaters (ordinary watercourses) flow northwards and coalesce to form West Brook, which becomes a Main River downstream of the A1198 near Hilton (approximately 8 kilometres (5 miles) downstream) (refer to Figure 13.1 of the Environmental Statement [TR010044/APP/6.2]). There are several tributaries to West Brook within the study area, which are referred to as WstB1 to WstB3, Nill Well Brook, and WstB5. West Brook was observed during the September 2019 site visit at the crossing of High Street in Yelling (NGR: TL 2604 6258), where it is culverted beneath the road (NGR: TL 26058 62659 to TL 26075 62500). It is clearly ephemeral, being mainly dry in September 2019, with some areas of standing water. The bed was observed to be heavily vegetated, channel width was around 1 metre, except where it widened beneath the road crossing to around 4 metres, and the bed was covered in fine sediment. The banks rise 1-2 metres from the channel bed at this location. There are existing drainage outfalls for road runoff. West Brook is designated under the Anglian RBMP as ‘West Brook’ (GB105033042730) (Ref 13-45). The West Brook WFD water body is designated as heavily modified. It is currently at Moderate Ecological Potential but failing to meet Good chemical status. It is at Moderate Ecological Potential due to phosphates and not all mitigation measures having been implemented. Known pressures and risks acting on this water body include: a. Physical modifications for flood protection and land drainage impacting invertebrates. b. Point source pollution from continuous sewage discharge and private sewage treatment impacting phosphate. c. Diffuse source pollution relating to livestock and poor nutrient management impacting phosphate.
Planning Inspectorate Scheme Ref: TR010044 40 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
West Brook is failing to meet Good chemical status due to priority substances (PBDE and PFOS). Using Wallingford Hydrosolutions Ltd LowFlows software at a point within the watercourse downstream of the Scheme before entry into West Brook, there is an estimated flow of 0.004 m3/s. 5.11 Bourn Brook Bourn Brook is an ordinary watercourse and rises from a number of small headwater ditches to the south of the existing A428 between Eltisley and the existing Caxton Gibbet roundabout (where it is known as Eastern Brook). The main stem is not affected by the Scheme, although there may be the need to extend existing culverts for some first order ditches in the vicinity of Pastures Farm (at the very head of the catchment on the divide with West Brook to the north). Bourn Brook is designated under the Anglian RBMP as ‘Bourn Brook’ (GB105033042690) (Ref 13-45). This is shown on Figure 13.1 of the Environmental Statement [TR010044/APP/6.2] to the south of the existing Caxton Gibbet roundabout. The main stem of this Water Framework Directive (WFD) designated watercourse is designated from its source in Eltisley to its confluence with the River Cam. The ‘Bourn Brook’ water body is designated as a heavily modified under the WFD. It is currently at Moderate Ecological Potential and failing to meet Good chemical status (2019) (Ref 13-45). It is at Moderate Ecological Potential due to fish and phosphate quality elements and not all mitigation measures having been implemented. Known pressures and risks acting on this water body include: a. Point source pollution from continuous sewage discharge impacting phosphate. b. Diffuse source pollution from poor nutrient management impacting phosphate. c. Physical modifications for flood protection impacting mitigation measures assessment and fish. d. Physical modifications for land drainage impacting fish due to sediment, hydrology and morphology pressures. Bourn Brook is failing to meet Good chemical status due to priority substances (PBDE and PFOS). Using Wallingford Hydrosolutions Ltd LowFlows software at a point within the watercourse downstream of the Scheme, there is an estimated flow of 0.001 m3/s.
Planning Inspectorate Scheme Ref: TR010044 41 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
6 Summary of aquatic ecology 6.1 River Great Ouse The River Great Ouse is a County Wildlife Site (CWS). The riparian habitats within the study area comprise a mix of emergent and marginal vegetation and trees and shrubs, mainly willows. The invasive non-native Himalayan (Indian) Balsam was found in the margins of the right bank. Otter (Lutra lutra) and Mink (Mustela lutreola) are present, but not Water Vole (Arvicola amphibius). As there will be no direct impact on the channel of the River Great Ouse from the crossing due to the construction of a clear span bridge structure that will be set back at least 8m from the banks, no field surveys were undertaken of fish or aquatic macroinvertebrates. However, data provided by the EA has been reviewed and is described below. The fish assemblage of the River Great Ouse is typical of many modified rivers in lowland England with an abundance of coarse fish. Barbel (Barbus barbus) are noted as being particularly prevalent, and the protected fish species European Eel (Anguilla anguilla), Bullhead (Cottus gobio) and Spined Loach (Cobitis taenia) are also found here. European bullhead and spined loach are Annex II species under the Habitats Directive (Council Directive 92/43/EEC) (Ref 13-63). European Eels are a protected species under the Eels (England and Wales) Regulations 2009 (Ref 13-15) and Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) (Ref 13-67). In terms of aquatic macroinvertebrates, the River Great Ouse is known to support Scarce Chaser (Libellula fulva), a nationally rare and potentially threatened dragonfly species (listed as a Red Data Book species) which is restricted in Bedfordshire to one short length of the River Great Ouse as it leaves the county at Wyboston and in a few of the nearby lakes. It has been known for many years to breed along the River Great Ouse from St. Neots to the Ouse Washes in Cambridgeshire. Macroinvertebrate data was provided by the EA for the River Great Ouse at Eaton Socon Mill, west of Eynesbury (TL 17571 58529). The invertebrate data includes Average Score Per Taxa (ASPT) and Biological Monitoring Working Party (BMWP) scores, which together can be used to evaluate sensitivity of macroinvertebrate communities to pollution (mainly organic pollution and nutrient enrichment). The BMWP scores reflect the sensitivity of macroinvertebrates to oxygen depletion, with scores below 10 suggesting that the watercourse is heavily polluted, and BMWP scores above 100 indicating water that is unpolluted. The most recent sample from the River Great Ouse taken in May 2019 had an ASPT value of 4.62 (out of a range of 0 to 10) and a BMWP score of 97, suggesting moderate pollution levels. No macrophyte survey data was provided by the EA for the River Great Ouse.
Planning Inspectorate Scheme Ref: TR010044 42 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
6.2 Stone Brook There is no data available on the UK Government website (Ref 13-68) for fish surveys of Stone Brook and none has been provided by the EA for this watercourse. Macroinvertebrate data was obtained from the UK Government data website (Ref 13-68) for Stone Brook at the B1043 crossing (TL 16625 54596). The most recent samples were from 2016 when 17 taxa were recorded on the 12 May and 12 taxa on the 19 October. The May samples had a BMWP score of 69 and an ASPT score of 4.06, indicative of moderate pollution levels. The October samples had a BMWP score was 39 and ASPT was 3.25. There are clearly significant pressures from pollution on Stone Brook which worsened later in the year. Macrophyte survey data was obtained from the UK Government data website for Stone Brook at Stone Bridge on the B1043 (TL 16625 54596). Stone Brook was most recently sampled in September 2013, with a RMNI score of 8.12, again indicating nutrient enrichment, which as noted at other watercourses is likely to be driven in part by the surrounding agricultural land uses. The assemblage was dominated by Elodea nuttallii, Cladophora, and Callitriche obtusangula. 6.3 Begwary Brook There is no data available on the UK Government website (Ref 13-68) for fish surveys of Begwary Brook and none has been provided by the EA for this watercourse. Macroinvertebrate data was obtained from the UK Government data website (Ref 13-68) for Begwary Brook at the A1 crossing in Wyboston, shortly upstream of the River Great Ouse (TL 16373 56440). The most recent samples were from 2018 when 18 taxa were recorded on two occasions. On 1 May 2018, Begwary Brook had a BMWP score of 83 and an ASPT score of 4.61. On 22 October 2018 the BMWP score was 93 and ASPT was 5.17. These values appeared to be relatively consistent between the two sampling periods and indicate moderate pollution levels. Macrophyte survey data was provided by the EA for Begwary Brook near Top Farm (TL 15044 56652). Begwary Brook was most recently sampled in June 2013, with a RMNI score of 8.46, indicating nutrient enrichment. The assemblage was dominated by Apium nodiflorum and Mentha. Evidence of Otter (Lutra lutra) was recorded along Begwary Brook during ecological surveys.
Planning Inspectorate Scheme Ref: TR010044 43 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
6.4 Hen Brook The section of Hen Brook that is potentially affected by the Scheme is heavily modified. The River Habitat Survey found evidence that it had been over- deepened and re-aligned through more than 33% of the length surveyed, which limits its value as an aquatic habitat. In addition, the downstream stretch of the survey area was culverted for approximately 30 metres. The Brook supports a range of species, including fish, aquatic invertebrates and various wetland plants in an otherwise managed agricultural landscape making the biodiversity value of the Hen Brook of local importance. The fish species caught on Hen Brook are typical of this habitat type, with no protected or invasive non-native fish species reported. No further surveys were recommended. However, fish survey data was available from the UK Government website for Hen Brook at Duck Lane in St Neots (TL 18576 59970), collected in April 2011. The Hen Brook survey location is approximately 1.9 kilometres (1.2 miles) downstream of the proposed crossing. The survey results were overwhelmingly dominated by roach (Rutilus rutilus), chub (Leuciscus cephalus), bleak (Alburnus alburnus), dace (Leuciscus leuciscus), gudgeon (Gobio gobio), perch (Perca fluviatilus), pike (Esox Lucius), rudd (Scardinius erythrophthalmus), silver bream (Blicca bjoerkna), common bream (Abramis brama) and tench (Tinca tinca) were also present in lower numbers. Macrophyte survey data was provided by the EA for Hen Brook at Cromwell Road, Eynsbury (TL 18951 59402). Hen Brook was most recently sampled in July 2016, with a River Macrophyte Nutrient Index (RMNI) score of 8.03. This indicates nutrient enrichment, likely to be driven in part by the adjacent agricultural land uses, including the probable widespread use of fertilisers. Vaucheria, Enteromorpha flexuosa and Elodea nuttallii were the most abundant taxa. Macroinvertebrate data was provided by the EA for Hen Brook at Cromwell Road, Eynesbury (TL 18951 59402). Hen Brook was also most recently surveyed in October 2018, with an ASPT score of 4.12 and BMWP score of 70 being recorded, with a previous survey in May 2018 having an ASPT score of 4.88 and BMWP of 78. This indicates more significant levels of pollution than that in the downstream River Great Ouse. A potential resting site for Otter (Lutra lutra) was identified during aquatic surveys on Hen Brook although no evidence of use could be confirmed. 6.5 West Brook Data available on the UK Government website (Ref 13-68) indicates that the most recent fish sample on West Brook was in 2012 at Turnpike Bridge (TL 31307 68636), in the village of Fenstanton. A single catch sample found roach to be dominant (124 specimens), with 3-spined stickleback (Gasterosteus aculeatus) being next most abundant (17 specimens). Other species present included European Eel (Anguilla Anguilla), dace, perch, 10-spined stickleback (Pungitius pungitius), minnow (Phoxinus phoxinus), rudd and chub. As noted above, European Eel is a protected species.
Planning Inspectorate Scheme Ref: TR010044 44 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
Macroinvertebrate data was obtained from the UK Government data website (Ref 13-68) for West Brook, where samples were taken at Fenstanton (TL 31572 68840). The most recent samples were from 2018 when 18 taxa were recorded on the 18 April and 16 taxa on the 2 November. The April samples had a BMWP score of 83 and an ASPT score of 4.61, and the October samples had a BMWP score was 81 and ASPT was 5.06. These values show a moderate pollution pressure on this watercourse throughout the year. Specific species data is not available within this dataset. Macrophyte survey data was obtained from the UK Government data website (Ref 13-68) for West Brook at Westend Road, Fenstanton (TL 30953 68268). West Brook was most recently sampled in July 2016, with a RMNI score of 7.94. This indicate nutrient enrichment, which is likely to be driven in part by the surrounding agricultural land uses, including the probable widespread use of fertilisers. Specific species data is not available within this dataset. 6.6 Bourn Brook Data available on the UK Government website (Ref 13-68Ref 13-68) indicates that the most recent fish sample on Bourn Brook was in 2019 at Westfield Farm (TL 38352 54840), to the south of Comberton. A catch depletion sample identified 1 stone loach (Barbatula barbatula), 33 minnow and ten bullhead (Cottus gobio). Bullhead is an Annex II species under the Habitats Directive (Ref 13-63). Macroinvertebrate data was obtained from the UK Government data website for Bourn Brook at the Caldecote road culvert, which is the closest monitoring location to the Scheme (TL 34692 56087). The most recent samples were from 2013 when 19 taxa were recorded on two occasions. On 28 May 2013, Bourn Brook had a BMWP score of 91 and an ASPT score of 4.79. On 11 October 2013 the BMWP score was 92 and ASPT was 4.84. These values appeared to be relatively consistent between the two sampling periods and indicate moderate pollution levels. Macrophyte survey data was obtained from the UK Government website for Bourn Brook (Ref 13-68) at the nearest sampling location at TL 33105 56379. Bourn Brook was most recently sampled here in June 2012, with a RMNI score of 8.11, indicating nutrient enrichment. No specific species data was available with this dataset. 6.7 Other watercourses Limited ecological information is available for the other watercourses in the study area as they are not regularly surveyed by the EA. However, all watercourses in the study area were surveyed for Water Vole (Arvicola amphibius), Otter (Lutra lutra) and Mink (Mustela lutreola). Evidence of Otter (Lutra lutra) was noted on South Brook.
Planning Inspectorate Scheme Ref: TR010044 45 Application Document Ref: TR010044/APP/6.3
A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 13.6: Water Resources Data
There were no past records of Water Vole (Arvicola amphibius) for any of the watercourses in a 1 kilometre (0.6 mile) radius search area of the Scheme for the past 10 years, apart from waterbodies 500-900 metres south-east of the existing Caxton Gibbet roundabout in 2009 and 2010 and surveys of Bourn Airfield in 2017-18, both of which are in a different catchment from the majority of the Survey Area. Surveys in July and August 2018 and April/May 2019 confirmed likely absence of Water Voles (Arvicola amphibius) within the Survey Area.
Planning Inspectorate Scheme Ref: TR010044 46 Application Document Ref: TR010044/APP/6.3