15_705_YOUN1 – Sisters Yard, Flood Risk Assessment of the Proposed Multi-Pitch Travellers Site Rev.02 – August 2016

FIGURE 2A – NSRI “Soilscape” Soil Types in the Sandycroft Area; Used to Indicate the Predominant Underlying Soil Types and Estimate Standard % Run-off of Rainfall (SPR), within the Local Catchment.

Key:

● – Loamy and Sandy soils with a naturally high groundwater and a peaty surface;

● – Slightly acid but base-rich Loamy and Clayey soils – slowly permeable and seasonally wet;

● – Free draining slightly acid Loamy soils; ● – River Dee;

The Site at Sisters Yard is located on an area of free-draining sub-soils, comprising Medium dense silty fine grained SAND, which extends for at least 750m radius from the Site and is assessed as having a Standard Percentage Runoff (SPR) of ~ 14.5%, from data on a site with very similar sub-surface geology.

15_705_YOUN1 – Sisters Yard, Deeside Flood Risk Assessment of the Proposed Multi-Pitch Travellers Site Rev.02 – August 2016

FIGURE 2B – BGS Borehole Logs in the Vicinity of the Site.

BH-SJ36NW251: A Borehole from June 1973, located ~65m N of the Site.

Groundwater Standing Water Level (SWL) - 2.6m bgl. 15_705_YOUN1 – Sisters Yard, Deeside Flood Risk Assessment of the Proposed Multi-Pitch Travellers Site Rev.02 – August 2016

BH-SJ36NW429: A Borehole from October 1980, located ~100m S of the Site

Groundwater SWL – 3.2m bgl. 15_705_YOUN1 – Sisters Yard, Deeside Flood Risk Assessment of the Proposed Multi-Pitch Travellers Site Rev.02 – August 2016

BH-SJ36NW259: A Borehole from June 1973, located ~145m NW of the Site.

Groundwater SWL – 2.7m bgl. 15_705_YOUN1 – Sisters Yard, Deeside Flood Risk Assessment of the Proposed Multi-Pitch Travellers Site Rev.02 – August 2016

BH-SJ36NW296: A Borehole from January 1987, located ~190m NE of the Site.

No Groundwater SWL was recorded for the upper Alluvial Deposits during construction of this Well. 15_705_YOUN1 – Sisters Yard, Deeside Flood Risk Assessment of the Proposed Multi-Pitch Travellers Site Rev.02 – August 2016

FIGURE 3 – Groundwater Vulnerability & Source Protection Zone Map.

Key:

● – Minor Aquifer, High; ● – Minor Aquifer, Low

● – Major Aquifer, High; ● – Major Aquifer, Intermediate;

● – Inner SPZ (Zone 1); ● – Outer SPZ (Zone 2); ● – Total Catchment (SPZ 3);

The Site is located in an area defined as a Minor Aquifer of High Vulnerability, located on free-draining sub-soils, which extends for at least 750m radius from the Site, beyond the western limit of a Total Catchment of a Major Aquifer for any Groundwater Abstraction in the area, with the nearest boundary of the Outer SPZ (Zone 2), approx. 2.0km to the south east. 15_705_YOUN1 – Sisters Yard, Deeside Flood Risk Assessment of the Proposed Multi-Pitch Travellers Site Rev.02 – August 2016

FIGURE 4A – River & Sea Levels.

The nearest water course to the Site is a drainage channel called Broughton Brook, which becomes the o Sandycroft Drain where it turns NE by 90 adjacent to the B5129 (see Figure 4B). This drainage channel runs alongside the north western boundary of the Site within a relatively deep narrow gorge, ~5m to the NW of the north western boundary and ~4-5m below the level of the Site at it’s nearest point, flowing in a SSW - NNE direction to the northwest of Station Road and joining up with a number of other drainage ditches from the west of the Site and alongside the railway lines <100m to the SW, that drain the area of Sandycroft, before eventually flowing into the River Dee at a point approx. 400m to the NE. Broughton Brook is Tidal up to and beyond the point it is adjacent to the Site, but is protected behind an existing Penstock Flood Gate located ~350m NE of the Site, near the entrance into the Willow Brook Park Retirement Homes complex and the outfall of the stream into the River Dee. 15_705_YOUN1 – Sisters Yard, Deeside Flood Risk Assessment of the Proposed Multi-Pitch Travellers Site Rev.02 – August 2016

FIGURE 4B – Streams and Drainage Channels in the Vicinity of the Site.

Broughton Brook originates from a small stream at Harwarden Golf Course and flows ~1.5km SE through a small reservoir before turning NE to drain the area to the S & SW of Airport. It then flows N & NE until it enters a straightened channel running alongside Manor Lane to the junction with Road and then WNW within a channel alongside the B5129 Chester Road until just past the junction with Station Road, where it is directed towards the NE and is renamed the Sandycroft Drain, flowing within a straightened channel to the NW of Station Road towards the River Dee, joining up with other drainage channels from the area and directed around the railway lines ~ 90m SW of the Site, before passing the Site <5m to the NW of the boundary and continuing NE towards the River Dee to outfall at a point ~400m NE of the Site. Other drainage channels named the Pentre Drain North & South continue alongside the B5129 ad drain the land south easterly towards the Sandycroft Drain and north westerly towards the A494, where it turns NE into a channel named the Queensferry Drain, that flows alongside the eastern boundary of the A494, until this main drainage channel also outfalls into the River Dee.

15_705_YOUN1 – Sisters Yard, Deeside Flood Risk Assessment of the Proposed Multi-Pitch Travellers Site Rev.02 – August 2016

5A – Flood Zones Map for Planning from Rivers & Sea.

●– Areas of a Floodplain which are developed but served by significant infrastructure, including Flood Defences - Flood Zone C1 (Based on EA Climate Change Flood Zone 2);

●– Areas of a Floodplain without any significant infrastructure, including Flood Defences - Flood Zone C2 (Based on EA Climate Change Flood Zone 2);

●– Areas Prone to Flooding in the past based on sediment evidence - Flood Zone B;

The Site is shown as wholly located with a Flood Zone C1, which would be subject to an annual probability of flooding from Rivers & Sea as <1 in 1,000, without the presence of the flood defences along the channel of the River Dee channel. The presence of the flood defences effectively eliminate a number of the potential Flood Risk scenarios for the Broughton Brook/ Sandycroft Drain to flood, including much of the risk of inundation of the area around Sandycroft by tidal flooding across a wide area, which is protected against by the Levees along the Dee Channel. There is a potential for Extreme Tides to overtop the NW Levee along the Dee Channel that could cause Flooding beyond the estuary end of Sandycroft Drain, either due to inland flow of tidal waters, or due to drainage water from the surrounding area to the west, south and south east adding to the depth of tidal water in the Sandycroft Drain and adjoining land, becoming hydraulically locked in the channel and unable to discharge into the River Dee until the tide recedes and creating a flood either side of this (and other) drainage channel. Flooding as a result of a surge of Tidal Waters directly up the Sandycroft Drain up to the Site is prevented by the presence of a simple Penstock/ Clack Valve Flood Gate ~350m NE of the Site on the northern end of Sandycroft Drain.

15_705_YOUN1 – Sisters Yard, Deeside Flood Risk Assessment of the Proposed Multi-Pitch Travellers Site Rev.02 – August 2016

FIGURE 5B – Flood Risk Map from Rivers & Sea.

●– Very Low Risk Areas Prone to Flooding – <1 in 1,000/yr Probability;

●– Low Risk Areas Prone to Flooding - >1 in 1,000/yr but <1 in 100/yr Probability;

●– Medium Risk Areas Prone to Flooding - >1 in 100/yr but <1 in 30/yr Probability;

●– High Risk Areas Prone to Flooding – >1 in 30/yr Probability;

When accounted for the Flood Defences along the River Dee Channel and the Flood Gate at the N end of the Sandycroft Drain, the Site is located entirely in a Low Flood Risk Area, although there is a small area of High Risk of Flooding adjacent to the Site’s NW boundary, but this does not impinge on the Site and is only shown as a small square because the Flood Map is completed as a series of pixels and at it’s lowest scale one (1) pixel is filled in, as the flood risk shown relates to water within the channel of the Broughton Brook/ Sandycroft Drain, which can become swollen due to very heavy seasonal rainfall and excess discharges of groundwater following very wet weather into the drainage network of this part of Queensferry and is predicted to occur within the 30yr return period. Blockage of the Sandycroft Drain by large volumes of debris flowing in the swollen stream following a peak rainfall event at the bridges upstream & downstream of the Site, is not a realistic flood scenario as the water flow in the stream will always be slow under any circumstances, due to the low lying topography of the area of Sandycroft.

N.B: The latest flood modelling predictions for >1in100yr FLE’s undertaken by the EA in the area of the Site, incorporate allowances for Climate Change effects over the coming 100yrs. 15_705_YOUN1 – Sisters Yard, Deeside Flood Risk Assessment of the Proposed Multi-Pitch Travellers Site Rev.02 – August 2016

FIGURE 5C – Modelled Flood Event Map for the Defended 100yr + Climate Change Return Period around the Site.

Modelling of the 100yr (Fluvial) Flood Events accounting for Climate Change has been undertaken by the EA and presented on the Map of the area shown above. This clearly shows that the area to the south of the B5129 Chester Road is predicted to flood at a return period of

●– Extent of Flood Zone 3 (Probability >1 in 100/yr FEL), allowing for Climate Change; 15_705_YOUN1 – Sisters Yard, Deeside Flood Risk Assessment of the Proposed Multi-Pitch Travellers Site Rev.02 – August 2016

FIGURE 5D – Modelled Flood Event Map for the Defended 1,000yr ( Climate Change Return Period around the Site.

Modelling of the 1,000yr (Fluvial) Flood Events has been undertaken by the EA and presented on the Map of the area shown above. This clearly shows that the area to the south of the B5129 Chester Road and a large part of the area to the north up to the Railway Lines directly to the south of the Site are predicted to flood at a return period of

●– Extent of Flood Zone 2 (Probability >1 in 1,000/yr FEL), allowing for Climate Change; 15_705_YOUN1 – Sisters Yard, Deeside Flood Risk Assessment of the Proposed Multi-Pitch Travellers Site Rev.02 – August 2016

FIGURE 5E – Flood Events Outlines from the Historical Record

The Historical Flood Event Map shows the extent of flooding during two (2) recent flood events in 1964 and September 1976. In both cases water flowing in the drainage channels exceeded the capacity and spilled out of the channels covering the adjacent land. In the case of the 1964 event, both Broughton Brook and the Sandycroft Drain flooded, with widespread surface water covering the area of the Airport and to the north & South of Broughton Brook and the adjacent B5129, with flood water extending up to the railway lines to the south of the Site and to the east of Station Road, but no further. So the extent of flooding was ~120m south of the Site at it’s nearest point.

In the later Flood Event of September 1976, again the capacity of the drainage channels was exceeded and area,s adjacent to both the Queensferry Drain and Broughton Brook/ Sandycroft Drain were again flooded, with surface water lying at a depth of ~225mm adjacent to Queensferry Drain and upto 90% of the fields adjacent to Broughton Brook and to the east of Station Water submerged or mostly covered with surface ponding. Again the closest this flooding got to the Site was back across the railway at the corner of the field nearest Station Road and the Railway Line, where the abutments of the Station Road bridge cross the railway lines, which is again ~120m south of Site at it’s nearest point. 15_705_YOUN1 – Sisters Yard, Deeside Flood Risk Assessment of the Proposed Multi-Pitch Travellers Site Rev.02 – August 2016

FIGURE 6A – Flood Risk from Surface Water.

●– Very Low Risk of Surface Water Flooding – <1 in 1,000/yr Probability;

●– Low Risk of Surface Water Flooding - >1 in 1,000/yr but <1 in 100/yr Probability;

●– Medium Risk of Surface Water Flooding - >1 in 100/yr but <1 in 30/yr Probability;

●– High Risk of Surface Water Flooding – >1 in 30/yr Probability;

The Site is located wholly in an area of Very Low Risk of Surface Water Flooding (SWF), due to the nature of the underlying Geology that is a Medium dense fine grained SAND, which has a relatively high -7 -4 permeability, with a Hydraulic Conductivity K in the range 2*10 to 2*10 m/s that will readily allow the infiltration of even the highest rainfall event. However the adjacent drainage channel of the Broughton Brook/ Sandycroft Ditch is prone to Low Risk of SWF at the banks adjacent to the Site, because the water course can become swollen due to very heavy seasonal rainfall and excess discharges of groundwater following very wet weather into the drainage network of this part of Queensferry which is predicted to result in flooding at the upper bank level of Broughton Brook every 100+ years, but not to impinge on the Site. A greater risk of SWF is predicted where the channel is restricted in a culvert passing beneath the road bridges at various points along Broughton Brook, with the nearest being at Factory Road between points 25m and 75m to the NE of the Site at the nearest point. 15_705_YOUN1 – Sisters Yard, Deeside Flood Risk Assessment of the Proposed Multi-Pitch Travellers Site Rev.02 – August 2016

FIGURE 6B – Flood Risk from Reservoirs.

The Site is not located within an area either likely to be flooded by a reservoir failure or even in an area of elevated potential risk of flooding from a reservoir and is not within <1.0km of any such flood risk within the same catchment, with the nearest boundary to a Reservoir Flood Risk Area approx. 800m NE of the Site across the River Dee Channel and within a different catchment.

N.B: This map shows the largest area that might be flooded if a reservoir was to fail, which is a Worst Case Scenario that is highly unlikely to occur, such that any actual flood would not cover the extent of the prediction. ●– Max. Extent of Flooding; 15_705_YOUN1 – Sisters Yard, Deeside Flood Risk Assessment of the Proposed Multi-Pitch Travellers Site Rev.02 – August 2016

FIGURE 7 – Flood Warning Areas.

The Site is located within a Flood Warning Area, associated with the flooding of the River Dee Channel and it’s tributaries/ drainage channels associated with the drainage of the Sandycroft area. The extent of the Flood Warning Area is associated with predictions of Tidal Flooding of the area at times of very high tide, in the absence of the existing Flood Defences, combined with extreme fluvial flow in the drainage channels causing overspill, when both water flows meet and combine. However, the Site is within an area which is protected by substantial Raised Levees along the banks of the River Dee Channel and a Flood Gate installed on Broughton Brook at a point ~350m NE of the Site, near it’s outfall into the River Dee, which has recently been upgraded to a Penstock Flood Gate at the northern outfall of Sanydroft Drain with the River Dee, monitored by CCTV, along with the water height and flow rate through the gate and could be closed remotely if necessary to prevent tidal waters inundating Broughton Brook, from the existing clack valve Flood Gate that is fitted to various other drainage channels in the area. Either of these Flood Gates offer adequate protection to the area behind the flood defences, preventing any tidal inundation of the drainage channel and preventing any flood upstream. The Flood Gate on Broughton Brook is one of a number on the drainage channels along this part of the River Dee, which together with the Raised Levees along the banks of the Dee Channel afford the area a substantial series of Flood Protection Measures, that are maintained and periodically improved by Natural Resources , to which all the properties within the protected area can benefit from, along the ~16km stretch of the from to the SE up to Connah's Quay in the NW, with Sandycroft roughly in the centre of this defended area.

● – Flood Warning Area; ● – Flood Alert Area; 15_705_YOUN1 – Sisters Yard, Deeside Flood Risk Assessment of the Proposed Multi-Pitch Travellers Site Rev.02 – August 2016

FIGURE 8A: Flood Protection Area from Tidal Defences

The Site is located well within an area benefiting from protection from Fluvial Flooding due to inundation of the various drainage channels in the area and a build-up and overspill of drainage water in the channels, by the installation and maintenance of either Penstock or Clack Valve Flood Gates at the ends of the various channels nearest the River Dee, as in the case of the Flood Gate on the Broughton Brook/ Sandycroft Ditch, together with Raised Levees along both banks of the River Dee Channel for a considerable distance upstream and downstream of Sandycroft. The extend of the Flood Protection Area extends south to at least the B5129 Chester Road east and in some cases beyond. But due to the simple nature of these flood defences, their construction and maintenance, they can be considered as permanent features and not just Flood Alleviation measures. Therefore, development of land for housing or other Higher Vulnerability Use within the protected zone of a Flood Zone C1 would be acceptable, including developments like the 3no Traveller’s Pitches with Mobile Homes, Dayrooms and Touring Caravans, proposed at the Site.

15_705_YOUN1 – Sisters Yard, Deeside Flood Risk Assessment of the Proposed Multi-Pitch Travellers Site Rev.02 – August 2016

FIGURE 8B – Flood Defences Map of Risk Management Assets

The Flood Gate was a simple one way flap gate (Clack Valve), located to the north of a short concrete housing and channel structure that removes any major debris or larger particles of soil/ gravel from channel flow before it enters the flood gate, which has been upgraded recently to a Penstock Flood Gate that can be monitored and remotely closed, this allowing the stream to flow into the River Dee, but closed shut if tidal water reaches the gate at High Tide and remains closed until the waters recede after the high tide event. The flood gate is routinely maintained by checking and replacing the door seals, greasing the hinges and clearing any build-up of tidal/ fluvial silts from the door seals and housing. 15_705_YOUN1 – Sisters Yard, Deeside Flood Risk Assessment of the Proposed Multi-Pitch Travellers Site Rev.02 – August 2016

FIGURE 9 – Location & Direction of the Emergency Escape Route along Station Road to the Railway Bridge ~5 to 6m above the Elevation of the Site and only ~130m walk SW of the Site Gateway.

FIGURE 10 – Flood Hazard: Safety Categories.