Public Inquiry - Stockeld Park/Hallam appeal.
The following position statement was appended to Mr Paul Crossan's closing statement on 20th Dec:
POSITION STATEMENT IN RELATION TO SURFACE AND GROUND WATER
Introduction
This position statement is produced further to the Inspector's request on Day 3 of the public inquiry, that the Appellants and Better Wetherby ("BW") summarise their respective positions in relation to surface and ground water issues. The Appellants and BW rely on their respective proofs of evidence, evidence in chief and through cross-examination, which seek to address the extent to which an existing hydrological relationship exists between the Appeal site and the Kirk Deighton SAC1 ("the SAC") and impacts of the proposed development. This position statement should be read in conjunction with that evidence. Further, the Appellant relies upon the Hydrological Assessment of May 2018 ("the HA") and the Ecology SOCG, the contents of the latter being agreed with the Council; and the position of Natural England, set out in the evidence.
Surface Water
The Appellants' position
Paragraph 2.3 of the Hydrological Rebuttal ("the Rebuttal") summarises the geological composition of the Site and its relationship with the SAC.
Paragraph 2.4 of the rebuttal describes local topography.
The SAC ponds lie in localised depressions on mudstone/limestone. The surface water runoff and catchment plan in Appendix 4 shows the surface water runoff routes, which flow perpendicular to the land contours. The indicative SAC/SSSI catchment provided in the HA is representative of the overland flow paths (represented by blue arrows) that provide surface water recharge to the SAC. Surface water runoff from the proposed development can be seen to contribute to a different catchment (represented by red arrows) flowing south of the SAC/SSSI and joining natural flow routes into west Wetherby.
Surface water runoff from the proposed development can therefore be seen not to contribute to the surface catchment of the SAC.
Surface water runoff is particularly relevant, due to the clay content of the soils. This is particularly so, when the ground is saturated during times of persistent rainfall. Viability of surface water runoff catchments is reinforced by the incomplete draining and lower permeability results of 7 out of 10 onsite soakaway tests (Section 8.2.6 of S.I. report Appendix 2), the alignment of surface water flow routes with Environment Agency surface water flood maps (Appendix 4 and Figure 1 — POE Appendix Point Al .2, and the Harrogate SFRA 178 surface water flood map brought in by BW) and there being between 0% and less than 25% risk of groundwater emergence indicating a low ground water table and impermeable soil conditions.
BW's Position
BW do not agree that Surface water runoff is significant factor, Natural England identify this character area as being predominantly free draining soils, important for aquifer recharge. Surface water ponds would tend to fill rapidly following heavy rainfall, the ponds all fill slowly after rainfall. Furthermore, there is no evidence of surface streams anywhere in the vicinity, this would be expected if water was flowing off such a large area.
We do agree that Appendix 4 indicates slope of land, and in the majority of the diagram could indicate direction of flow IF runoff was present. We would however contend that where the slope of land becomes negligible, at the east of the diagram, then there would not be any runoff and the water would tend to form a pond, or enter the local water table This is an area less than I metre higher than the SAC and is likely to be within the dip/hollow of limestone forming the SAC. The superficial covering here is "Glacio-fIuvial Terrace Deposits. Devensian - Sand and gravel" these are permeable and of unknown thickness, but are likely to enable water to flow into the SAC. The flow towards Wetherby is unsubstantiated and there is no indication of drainage channels or streams.
We note that Section 8.3 of the Appellants SI report, Appendix 2, identified that the 'small scale' of the soakaway results may not have intercepted joints, and that further work might identify the feasibility of using soakaways. The report (section 15.5.1) also identified that the majority of the site was on "granular residual soils", which we believe would be free draining in accordance with the Natural England Characterisation
Ground Water
Appellants' Position
Paragraph 2.5 of the Rebuttal refers to the underlying bedrock of the Site as being Lower Magnesium Limestone ("LML") bedrock, with a south easterly plunge (dip direction).
The East-West fault line shows a downthrow indicating the dropping of the bedrock north of the fault. The fault does not alter the direction of the dip but the fracturing of this sedimentary rock creates a preferential flow path along its length, directing flow South-East.
Any infiltration at the proposed development site through to the LML is therefore directed towards the River Wharfe.
To the extent that surface water originating from the proposed development infiltrates into the bedrock, groundwater flows will also follow the south easterly plunge (dip direction) away from the SAC.
Appendix 6 of the Rebuttal shows the groundwater flooding drop down menu and corresponding map. This demonstrates that the pond at "Field A" is fed by groundwater as the map area is highlighted in white which represents 0% risk of groundwater emergence. Rather, it is fed by surface water runoff.
The groundwater flow plan in Figure I (Paragraph Al .2) of Mr Howard's proof of evidence is incorrect as it ignores the impermeable soil and ground in the northern half of the proposed development and assumes groundwater emergence feeding temporary ponds and the SAC, when the "Areas Susceptible to Ground Water Flooding" option of the SFRA map 178 (Appendix 6 of the rebuttal report) shows there to be between 0% and less than 25% risk of groundwater emergence in the area.
BW's Position
BW identified that the appellant was using an old and out of date Geological map in Appendix 6. The terminology related to Magnesian (not Magnesium) has not been in use for many years, and the map bore no resemblance to the ones used in the original hydrology report, for instance the major fault close to the site is not depicted. The latest map, as provided to the Inquiry, clearly shows a north-easterly dip (not plunge) of the bedrock. Permian (aka Magnesian) limestones transport water via fractures and fissures in a predominantly down dip direction, which would direct water straight towards the SAC. This NE dip clearly undermines much of the appellants information and suggests that water could not flow in a SE direction towards the River Wharfe.
The appellant suggested that this latest map 'perhaps' did not maintain historic information, we would suggest that this is both unfounded and unlikely.
We also provided a newly downloaded 'Harrogate SFRA 178 surface water flood map', we contend that this clearly shows a large risk (up to 75%) of Groundwater flooding in the area. This map can also be filtered to suggest no risk of surface water flooding.
Overall Conclusion
Appellants
Overall, the Appeal Site does not form part of the SAC/SSSI catchment either for groundwater or surface water flows. There is no objective evidence to refute that position. There is a very low likelihood, if at all, of water originating from the Appeal Site reaching the SAC/SSSI. The effect of the proposed development on the surface and groundwater flows would have no more than an insignificant/de minimis effect, if any.
BWP
I contend that the principal mode of drainage from the proposed site is via groundwater, and that the SAC/SSSI is directly 'downstream' of the site. We would also contend that any surface run-off, such as might occur in extremely heavy rainfall /thunderstorm events, is also likely to be predominantly directed to the SAC via a rise in the local water table near the SAC. I believe that the appellants 'evidence' is predominantly flawed and based on information gleaned from old or incorrect maps and that the proposed development is very likely to significantly reduce water inflow into the SAC; this would have a serious detrimental effect on the habitat
The following position statement was appended to Mr Paul Crossan's closing statement on 20th Dec:
POSITION STATEMENT IN RELATION TO SURFACE AND GROUND WATER
Introduction
This position statement is produced further to the Inspector's request on Day 3 of the public inquiry, that the Appellants and Better Wetherby ("BW") summarise their respective positions in relation to surface and ground water issues. The Appellants and BW rely on their respective proofs of evidence, evidence in chief and through cross-examination, which seek to address the extent to which an existing hydrological relationship exists between the Appeal site and the Kirk Deighton SAC1 ("the SAC") and impacts of the proposed development. This position statement should be read in conjunction with that evidence. Further, the Appellant relies upon the Hydrological Assessment of May 2018 ("the HA") and the Ecology SOCG, the contents of the latter being agreed with the Council; and the position of Natural England, set out in the evidence.
Surface Water
The Appellants' position
Paragraph 2.3 of the Hydrological Rebuttal ("the Rebuttal") summarises the geological composition of the Site and its relationship with the SAC.
Paragraph 2.4 of the rebuttal describes local topography.
The SAC ponds lie in localised depressions on mudstone/limestone. The surface water runoff and catchment plan in Appendix 4 shows the surface water runoff routes, which flow perpendicular to the land contours. The indicative SAC/SSSI catchment provided in the HA is representative of the overland flow paths (represented by blue arrows) that provide surface water recharge to the SAC. Surface water runoff from the proposed development can be seen to contribute to a different catchment (represented by red arrows) flowing south of the SAC/SSSI and joining natural flow routes into west Wetherby.
Surface water runoff from the proposed development can therefore be seen not to contribute to the surface catchment of the SAC.
Surface water runoff is particularly relevant, due to the clay content of the soils. This is particularly so, when the ground is saturated during times of persistent rainfall. Viability of surface water runoff catchments is reinforced by the incomplete draining and lower permeability results of 7 out of 10 onsite soakaway tests (Section 8.2.6 of S.I. report Appendix 2), the alignment of surface water flow routes with Environment Agency surface water flood maps (Appendix 4 and Figure 1 — POE Appendix Point Al .2, and the Harrogate SFRA 178 surface water flood map brought in by BW) and there being between 0% and less than 25% risk of groundwater emergence indicating a low ground water table and impermeable soil conditions.
BW's Position
BW do not agree that Surface water runoff is significant factor, Natural England identify this character area as being predominantly free draining soils, important for aquifer recharge. Surface water ponds would tend to fill rapidly following heavy rainfall, the ponds all fill slowly after rainfall. Furthermore, there is no evidence of surface streams anywhere in the vicinity, this would be expected if water was flowing off such a large area.
We do agree that Appendix 4 indicates slope of land, and in the majority of the diagram could indicate direction of flow IF runoff was present. We would however contend that where the slope of land becomes negligible, at the east of the diagram, then there would not be any runoff and the water would tend to form a pond, or enter the local water table This is an area less than I metre higher than the SAC and is likely to be within the dip/hollow of limestone forming the SAC. The superficial covering here is "Glacio-fIuvial Terrace Deposits. Devensian - Sand and gravel" these are permeable and of unknown thickness, but are likely to enable water to flow into the SAC. The flow towards Wetherby is unsubstantiated and there is no indication of drainage channels or streams.
We note that Section 8.3 of the Appellants SI report, Appendix 2, identified that the 'small scale' of the soakaway results may not have intercepted joints, and that further work might identify the feasibility of using soakaways. The report (section 15.5.1) also identified that the majority of the site was on "granular residual soils", which we believe would be free draining in accordance with the Natural England Characterisation
Ground Water
Appellants' Position
Paragraph 2.5 of the Rebuttal refers to the underlying bedrock of the Site as being Lower Magnesium Limestone ("LML") bedrock, with a south easterly plunge (dip direction).
The East-West fault line shows a downthrow indicating the dropping of the bedrock north of the fault. The fault does not alter the direction of the dip but the fracturing of this sedimentary rock creates a preferential flow path along its length, directing flow South-East.
Any infiltration at the proposed development site through to the LML is therefore directed towards the River Wharfe.
To the extent that surface water originating from the proposed development infiltrates into the bedrock, groundwater flows will also follow the south easterly plunge (dip direction) away from the SAC.
Appendix 6 of the Rebuttal shows the groundwater flooding drop down menu and corresponding map. This demonstrates that the pond at "Field A" is fed by groundwater as the map area is highlighted in white which represents 0% risk of groundwater emergence. Rather, it is fed by surface water runoff.
The groundwater flow plan in Figure I (Paragraph Al .2) of Mr Howard's proof of evidence is incorrect as it ignores the impermeable soil and ground in the northern half of the proposed development and assumes groundwater emergence feeding temporary ponds and the SAC, when the "Areas Susceptible to Ground Water Flooding" option of the SFRA map 178 (Appendix 6 of the rebuttal report) shows there to be between 0% and less than 25% risk of groundwater emergence in the area.
BW's Position
BW identified that the appellant was using an old and out of date Geological map in Appendix 6. The terminology related to Magnesian (not Magnesium) has not been in use for many years, and the map bore no resemblance to the ones used in the original hydrology report, for instance the major fault close to the site is not depicted. The latest map, as provided to the Inquiry, clearly shows a north-easterly dip (not plunge) of the bedrock. Permian (aka Magnesian) limestones transport water via fractures and fissures in a predominantly down dip direction, which would direct water straight towards the SAC. This NE dip clearly undermines much of the appellants information and suggests that water could not flow in a SE direction towards the River Wharfe.
The appellant suggested that this latest map 'perhaps' did not maintain historic information, we would suggest that this is both unfounded and unlikely.
We also provided a newly downloaded 'Harrogate SFRA 178 surface water flood map', we contend that this clearly shows a large risk (up to 75%) of Groundwater flooding in the area. This map can also be filtered to suggest no risk of surface water flooding.
Overall Conclusion
Appellants
Overall, the Appeal Site does not form part of the SAC/SSSI catchment either for groundwater or surface water flows. There is no objective evidence to refute that position. There is a very low likelihood, if at all, of water originating from the Appeal Site reaching the SAC/SSSI. The effect of the proposed development on the surface and groundwater flows would have no more than an insignificant/de minimis effect, if any.
BWP
I contend that the principal mode of drainage from the proposed site is via groundwater, and that the SAC/SSSI is directly 'downstream' of the site. We would also contend that any surface run-off, such as might occur in extremely heavy rainfall /thunderstorm events, is also likely to be predominantly directed to the SAC via a rise in the local water table near the SAC. I believe that the appellants 'evidence' is predominantly flawed and based on information gleaned from old or incorrect maps and that the proposed development is very likely to significantly reduce water inflow into the SAC; this would have a serious detrimental effect on the habitat
