lakeland dairies co -operative society ltd. bailieboro · environmental impact statement (eis) –...

Environmental Impact Statement (EIS) – Lakeland Dairies Co

Lakeland Dairies Co-Operative Society Ltd - Lear, Bailieborough, Co. Cavan Lear, Bailieborough, Co. Cavan

Lakeland Dairies Co

Environmental Impact Statement

Lakeland Dairies Co-operative Society Ltd.

Bailieboro


Appendix

Flood Risk Assessment

152

operative Society Ltd.

Bailieboro


Appendix B


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Location: Bailie Foods, Bailieboro, Co.

Prepared for: Nevin Traynor, Traynor Environmental Ltd.

Prepared by:

Colin O’Reilly BAgrSc, PhD

Date: 16/07/14

Reference no. 1264

Lakeland Dairies Co-Operative Society Ltd - Lear, Bailieborough, Co. Cavan


Bailie Foods, Bailieboro, Co. Cavan

Nevin Traynor, Traynor Environmental Ltd.

Lear, Bailieborough, Co. Cavan

10.0

10.1

Introduction

The following flood risk assessment has been prepared by Colin O’Reilly BAgrSc PhD, of Envirologic

Traynor of Traynor Environmental Ltd.

This report is intended to satisfy the requirements of Cavan County Council, Environmental Protection Agency and Office of

Public Works, relating to a proposed development at Bailieboro, Co

be incorporated into the current food processing activities at the site. A re

facilitate the proposed development. The flood risk assessment will form pa

As per the Flood Risk Management Guidelines (2008), where flood risk may be an issue for any proposed development, a flood

risk assessment (FRA) should be carried out that is appropriate to the scale and nature of

arising. The flood risk assessment outlined herein is intended to be sufficiently detailed to quantify the risks and effects

flooding, necessary mitigation measures, together with recommendations on how to best manage

the document ‘The Planning System and Flood Risk Management (2008)’ the flood risk assessment will consist of the following

sections:

• site description

• site layout

• S-P-R model; sequential approach; justification test

• determination of flood level

• mitigation measures

• conclusions

A site walkover and survey of local hydrology was performed by Envirologic on 8th

Site Description

Site Location

Bailie Foods is a creamery and food processing plant located along the

of Bailieboro. The site is divided on each site of the road, with approximately 5 hectares on the western side and 3 hectare

on the eastern side.

The site is located within a typically drumlin landscape in east Cavan. The local drumlin hills peak at 160

that appear to be elongated along a northwest orientation though this is not entirely consistent. Site topography rises from

136 mOD at the southeastern boundary up to 141 mOD at

mid-slope within a carved river valley.

Maximum elevations in the area are observed at Taghart (290 mOD), 5 km to the northeast, and Corraweelis (339 mOD), 5 km

to the southeast. Lowest elevations are observed in the many valleys, and intermediate loughs.

General land use in the surrounding area is predominantly grassland, supporting dairy, beef and sheep farming. The Castle

Estate to the northwest has been afforested, and minor forestry pla

pitches are situated adjacent to the southeast border. Agriculture declines approaching Bailieboro with the periphery of the

town defined by a large supermarket 800 m south of the site. Housing densit

The following flood risk assessment has been prepared by Colin O’Reilly BAgrSc PhD, of Envirologic Ltd., on behalf of Nevin


Public Works, relating to a proposed development at Bailieboro, Co. Cavan. The proposed development is a dryer which will

be incorporated into the current food processing activities at the site. A re-alignment of the River Lear is necessary to

facilitate the proposed development. The flood risk assessment will form part of an Environmental Impact Statement.


risk assessment (FRA) should be carried out that is appropriate to the scale and nature of the development and the risks

arising. The flood risk assessment outlined herein is intended to be sufficiently detailed to quantify the risks and effects

flooding, necessary mitigation measures, together with recommendations on how to best manage any residual risks. As per


R model; sequential approach; justification test

A site walkover and survey of local hydrology was performed by Envirologic on 8th-9th June 2014.

Bailie Foods is a creamery and food processing plant located along the R178, connecting Bailieboro with Shercock, 1 km north

of Bailieboro. The site is divided on each site of the road, with approximately 5 hectares on the western side and 3 hectare

cape in east Cavan. The local drumlin hills peak at 160-180 mOD with tails


136 mOD at the southeastern boundary up to 141 mOD at the northwestern boundary. Site position is on the toe


ations are observed in the many valleys, and intermediate loughs.


Estate to the northwest has been afforested, and minor forestry plantations exist to the northeast of the site. Two GAA


town defined by a large supermarket 800 m south of the site. Housing density in the immediate surrounds of the site is low.

153

Ltd., on behalf of Nevin


. Cavan. The proposed development is a dryer which will

alignment of the River Lear is necessary to

rt of an Environmental Impact Statement.


the development and the risks

arising. The flood risk assessment outlined herein is intended to be sufficiently detailed to quantify the risks and effects of any

any residual risks. As per


R178, connecting Bailieboro with Shercock, 1 km north

of Bailieboro. The site is divided on each site of the road, with approximately 5 hectares on the western side and 3 hectares

180 mOD with tails


the northwestern boundary. Site position is on the toe-slope to



ntations exist to the northeast of the site. Two GAA


y in the immediate surrounds of the site is low.

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Environmental Impact Statement (EIS) – Lakeland Dairies Co-Operative Society Ltd - Lear, Bailieborough, Co. Cavan 154

Site Layout & Proposed Works

Milk is received at the creamery on the western side of the local road. Raw product is pumped to the eastern site for

processing. An ESB substation is located adjacent to the eastern site boundary. The majority of the site area is in

hardstanding.

The eastern site is quite flat. The proposed development area is in the southeastern corner of the eastern site. Relevant site

elevations are as follows:

• road at site entrance = 136.1 mOD

• site entrance = 136.4 mOD

• front car park = 136.9 mOD

• factory finished floor level = 137.0 mOD

• security hut finished floor level = 137.0 mOD

• chemical bund top = 137.8 mOD

• hardstanding on southern boundary = 136.9 mOD

• hardstanding on eastern boundary = 135.5 - 136.0 mOD

• bund top to ESB substation = 135.87 mOD

• yard to north used by haulage vehicles = 136.1 - 136.7 mOD

The western site slopes from the road to the northwest. Relevant site elevations are as follows:

• road at site entrance = 136.4 mOD

• hardstanding on southern boundary = 134.5 mOD

• ground level at on-site well = 140.26 mOD

Process water is sourced from a combination of Castle Lough (900 m3 d

-1) and an on-site groundwater well. Liquid effluent

from the processing facility is transferred to the wastewater treatment plant. Treated effluent is currently discharged to the

River Lear to the north of the site at a rate of 650 m3 d

-1. Cooling water condensate is transferred to the River Lear on the

eastern site boundary at a rate of 1,450 m3 d

-13.

From the recent review of the IED license an increase has been granted for the WWTP discharge to 1,300 m3 d

-1. The cooling

water amount of 1,450 m3 d

-1 per day will remain the same. The new combined discharge will be transferred to Castle Lough

as a single discharge (2,750 m3 d

-1). No date has been confirmed for this alteration.

A series of ponds to the north of the site are used to store fire water.

10.2 Geology & Hydrogeology

Soils

Deep poorly-drained acidic mineral soils dominate the landscape. This soil unit occupies much of east and central Cavan. It is

classified by Gardiner and Radford (1980) as a wet, mineral, organic drumlin soil composed of an imperfectly to poorly drained

surface water gley of loam to clay loam texture and of medium base status. Surface structure is a weak crumb, becoming

massive at about 30 cm, below which soil consistence is plastic and root penetration poor. Drainage impedance is attributed

to the heavy texture. The retentive nature of the subsoil predisposes it to periodic water saturation, and a seasonal ‘perched’

water table results. The main soil (40%) in the association consists of a moderately well-drained acid brown earth of loam to

clay loam texture. This soil is shallower and freer draining in places, usually, but not exclusively, on elevated ground.

The River Lear is flanked by alluvium, deposited as part of historical flood plains and this infers it is a naturally formed channel.

Some very low-lying lands, such as those to the west of the western side have fully degraded to peat due to their landscape

position and constant waterlogging. These peats surround the fringes of Castle Lough.

Subsoils

Drumlins consist of a thick cover of boulder clay deposited in the form of small hills, typically oval in plan. These heavy boulder

clays are derived from Palaeazoic sandstones and shales. Subsoil depth is deeper in the valleys, thinning considerably on

elevated areas and steeper slopes.

Bedrock & Structural Geology

The site is underlain by the Shercock Formation, described as fine to coarse grained turbidite. This bedrock is classified as

Silurian metasediments and volcanics, which form part of the Longford-Down inlier. Structural faulting is on a southeast-

northwest plane although no major faulting occurs within the vicinity of the site.

Aquifer Classification

The underlying aquifer is classified as generally unproductive bedrock except for local zones. The GSI estimate the maximum

recharge at the site to be in the region of 100 mm.

Groundwater vulnerability at the site is classified as High. Vulnerability declines to Moderate and Low on raised grounds as a

function of unsaturated subsoil depth.

A groundwater well is in use at the site with an estimated abstraction of 180 m3 d

-1 (GSI, 2004).

10.3 Hydrology

Catchment Description

The River Lear is the primary watercourse in the area, and is the watercourse being subjected to realignment. The catchment

of the River Lear to Lear Bridge is 20.9 km2. The river is formed from a collection of first order streams that rise on elevated

grounds to the northeast and east, at Taghart (O’Reilly Concrete quarry which has an active discharge) and Leiter, respectively.

Surface water elevations in the wider area, as surveyed on 8th July 2014, are shown in Figure 2.

The river flows westwards through agricultural lands in Pottle Lower. The stream receives a discharge from the on-site

wastewater treatment plant, before passing through a section flanked by open lagoons which were previously integrated

constructed wetlands, used as part of the treatment process. Hydraulic gradient through this section is low. The river then

flows south adjacent to the eastern site boundary. The river receives flow from a small stream to the eastern side of two GAA

pitches through a concrete culvert before itself passing through 3 parallel concrete culverts. Surface water elevations in the

vicinity of the site, as surveyed on 9th July 2014, are shown in Figure 3.

The stream continues westwards, passing beneath Lear Bridge at the site entrance and adjacent to the southern site

boundary. The river enters a forested area 800 m northwest of the site entrance before flowing into Castle Lough a further

400 m downstream.

Surface waters continue to flow southwest through a series of interconnected open sections and lakes, through Killinkere,

before entering Lough Ramor in Virginia. The outfall of Lough Ramor forms the Blackwater River which enters the River Boyne

at a confluence in Navan, and discharges to the Irish Sea at Drogheda.

The relevant catchment sizes are as follows:

• WWTP discharge point = 18.7 km2

• Upgradient junction of original and current channel = 19.4 km2

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• Tri-culvert on eastern site boundary = 20.9 km

• Lear Bridge (upstream) = 20.9 km

• Lear Bridge (downstream) = 22.6 km

• Castle Lough = 26.1 km

10.4 Flooding History

There is no known history of flooding at the site. Consultation of the OPW flood maps show that there are no mapped

historical flood events in the vicinity of the site. The nearest mapped flood events are at:

1. Beckscourt - 800 m to the south,

2. Bailieboro Lake - 1.3 km to the southwest, which floods a significant area every year after heavy rainfall.

3. Drumlon - 2.7 km northeast, low lying lands which are prone to flooding every year after heavy rainfall.

None of these locations prone to annual flooding are within the River Lear catchment to the site.

Historical OS six inch maps show no clear evidence of flooding in the vicinity of the site.

Plate 1 shows Map 321 of the Preliminary Flood Risk Assessment (OPW

pluvial flooding. There is no apparent risk of fluvial flooding during extreme flood events.

10.5 Sequential Test

The sequential approach is used to

accordance with the Guidelines (DoEHLG, 2008). As shown in Plate 2, Zone A, applied to areas with a high probability of

flooding, defines areas with the highest

Development in this zone should be avoided and/or only considered in exceptional circumstances. Development should only

be permitted in areas at risk of flooding when th

also meet the objectives of proper planning and sustainable development. Zone B is applied to areas with a moderate


culvert on eastern site boundary = 20.9 km2

Lear Bridge (upstream) = 20.9 km2

Lear Bridge (downstream) = 22.6 km2

Castle Lough = 26.1 km2



800 m to the south, which occurs annually on low-lying lands;

1.3 km to the southwest, which floods a significant area every year after heavy rainfall.

2.7 km northeast, low lying lands which are prone to flooding every year after heavy rainfall.

one of these locations prone to annual flooding are within the River Lear catchment to the site.


Plate 1 shows Map 321 of the Preliminary Flood Risk Assessment (OPW, 2011). There are no areas shown to be at risk of


Plate 1 pFRA Map (site location marked in red)

The sequential approach is used to assess flood risk at the site and, where there is variability, to assign appropriate zones in


flooding, defines areas with the highest risk of flooding from rivers (i.e. more than 1% probability or more than 1 in 100).


be permitted in areas at risk of flooding when there are no alternative, reasonable sites available in areas at lower risk that





1.3 km to the southwest, which floods a significant area every year after heavy rainfall.

2.7 km northeast, low lying lands which are prone to flooding every year after heavy rainfall.

one of these locations prone to annual flooding are within the River Lear catchment to the site.


, 2011). There are no areas shown to be at risk of


assess flood risk at the site and, where there is variability, to assign appropriate zones in


risk of flooding from rivers (i.e. more than 1% probability or more than 1 in 100).


ere are no alternative, reasonable sites available in areas at lower risk that


10.6

10.7

probability of flooding from rivers. (i.e. a 0.1% to 1% pro

probability of flooding. The Flood Risk Assessment will clarify within which zone the site lies.

Plate 2 - Use of the sequential approach to assign flood risk zones (DoEHLG, 2008)

Justification Test

The proposed development consists of an industrial unit in the southeastern corner of the site. The proposed development is

deemed to be relevant in relation to the ongoing activities at the site. As such the process is advanced t

that, in line with the Guidelines (DoEHLG, 2008), the flood risk assessment should demonstrate:

1. the development will not increase flood risk elsewhere and, if possible will reduce overall flood risk;

2. the development proposal includes measures to minimise flood risk to people, property and the economy and the

environment as far as reasonably possible and to ensure that residual risks to the area and/or development can be

managed to an acceptable level as regards the adequacy of existing

implementation and funding of any future flood risk management measures;

3. it is justified that there are wider sustainability grounds for appropriate development and flood risk can be reduced

overall;

4. the development will ensure effective management of residual risks.

S-P-R Model

The flood risk assessment is carried out using the source

is used to identify the sources of flood water, the peopl

the flood water reaches those receptors. Consideration will be given to the predominant sources, pathways and receptors in

terms of the influence they have on site flooding, or the man

on site are shown in Table 1.

probability of flooding from rivers. (i.e. a 0.1% to 1% probability or between 1 in 100 and 1 in 1000), with Zone C having a low

probability of flooding. The Flood Risk Assessment will clarify within which zone the site lies.

Use of the sequential approach to assign flood risk zones (DoEHLG, 2008)


deemed to be relevant in relation to the ongoing activities at the site. As such the process is advanced to Part 2 which states

that, in line with the Guidelines (DoEHLG, 2008), the flood risk assessment should demonstrate:

the development will not increase flood risk elsewhere and, if possible will reduce overall flood risk;

measures to minimise flood risk to people, property and the economy and the


managed to an acceptable level as regards the adequacy of existing flood protection measures of the design,

implementation and funding of any future flood risk management measures;

it is justified that there are wider sustainability grounds for appropriate development and flood risk can be reduced

t will ensure effective management of residual risks.

The flood risk assessment is carried out using the source-pathway-receptor (S-P-R) model, as outlined below. The S

is used to identify the sources of flood water, the people and assets affected by potential flooding, and the pathways by which


terms of the influence they have on site flooding, or the manner in which they may be impacted. The primary water sources

155

bability or between 1 in 100 and 1 in 1000), with Zone C having a low


o Part 2 which states

measures to minimise flood risk to people, property and the economy and the


flood protection measures of the design,

it is justified that there are wider sustainability grounds for appropriate development and flood risk can be reduced

R) model, as outlined below. The S-P-R model

e and assets affected by potential flooding, and the pathways by which


ner in which they may be impacted. The primary water sources

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Table 1 – Preliminary S-P-R

Sources Pathways Receptors

Storm rainfall event

(1 in 100 year)

pluvial flooding finished floor level of

existing factory

River Lear fluvial flooding finished floor level of

proposed factory

Stormwater from

hardstanding

site stormwater network River Lear

Outfall from urban storm

network

municipal stormwater

network

ESB substation

firewater retention ponds bunded chemical stores

WWTP discharge

Flooding mechanisms will be looked at in more detail to quantify risk to the current channel under the current scenario, and

any change in flood risk to the surrounds due to proposed stream re-alignment works. Mitigation measures will then be

applied as appropriate.

10.8 Flooding Mechanisms

It is clear that the River Lear is the primary source of potential flooding to the site. It is necessary to assess fluvial flood risk

from this watercourse. This will be done by firstly determining flood flows in the river as it passes the site, and subsequently

compiling a model which will allow determination of flood levels when this flood flow is passed through a series of surveyed

cross sections. The model will be adjusted to simulate the re-alignment of the River Lear to the east of the site.

Gauged Method

The most accurate method for determining flood flows is through statistical interpretation of historical data collected at a

hydrometric station on the watercourse in question. There is no hydrometric gauge on the River Lear in the area upgradient of

Castle Lough. Disused hydrometric gauges were observed on the River Lear at Lear Bridge and the treated effluent outfall. No

historical data exist for these gauges.

Ungauged Method

The median annual maximum flood magnitude, QMED, as outlined in the FSU (Nicholson and Bree, 2013) is now preferred as

opposed to the Qbar parameter as described in the FSR (1975). The median is less sensitive to large extreme floods and to

flood measurement error in general. The estimation method for ungauged locations is based on a regression analysis relating

to observed QMED to physical catchment descriptors (PCDs) at gauged locations in Ireland, given by the following equation:

QMEDrural = 1.237 x 10-5

. AREA0.937

. BFIsoil-0.922

. SAAR1.306

. FARL2.217

. DRAIND0.341

. S0.185

. (1 + ARTDRAIN2) 0.408

The PCDs applicable to the subject site are shown in Table 2.

Table 2 – Physical catchment descriptors applicable to the subject site

PCD Description Units Subject site

value

km2 21.50

AREA catchment area mm 1,031

SAAR average annual rainfall 0.48

BFIsoil baseflow index dervied from soils data 1.00

FARL flood attenuation from reservoirs and lakes km km2 0.84

DRAIND ratio of river network to catchment area m km-1

7.32

S1085 slope of the main stream between the 10 and 85

percentiles of the main stream

0.00

ARTDRAIN2 proportion of the river netwrrok that is included

in drainage schemes

QMED 4.96

A principle of the FSU is the concept of a pivotal site, which is defined as the gauging station that is considered most relevant

to a particular flood estimation problem at the subject site, and is used to adjust the QMED rural estimate. In this case the

downstream gauging station at Virginia Hatchery was used as the pivotal site. The procedure is to infer an adjustment factor

to the QMEDrural estimate by examining the performance of the regression model at the pivotal site. This adjustment factor

yields the following QMED at the site:

QMEDrural, adjusted = 3.40 m3 s

-1

The QMED equation has a factorial standard error of 1.37, which means that there is approximately a 66% chance of lying

between 0.73 and 1.37 times the estimate, hence:

QMED = 3.40 m3 s

-1 x 1.37

QMED = 4.66 m3 s

-1

The return-period flood flow (QT) is determined by an index flood method, whereby a growth factor as determined from an

EV1 distribution plot is applied. In this case:

QT = QMED x XT

Q100 = 4.66 m3 s

-1 x 2.65

Q100 = 12.35 m3 s

-1

Finally, a climate change growth factor of 20% is applied:

Q100 = 12.35 x 1.2

Q100 = 14.8 m3 s

-1

For comparison purposes, the Q100 flood flow was also calculated using the FSR 6-variable equation, as provided by the Flood

Studies Report (NERC, 1975):

QBAR = c x AREA0.94

. STMFRQ0.27

. SOIL1.23

. RSMD1.03

. S10850.16

. (1 - LAKE) -0.85

where:

QBAR = 1 in 1 year flow (m3 s

-1)

c = regression coefficient specific to Ireland = 0.0172

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AREA = catchment area (km2) = 21.5

STMFRQ = stream frequency in terms of the average number of stream junctions per km2

= 11/21.5 = 0.51

S1085 = representative channel slope (in m km-1

) defined by points 10% and 85% upstream from the outflow

point of the catchment = (144.15 - 133.37) / 1.96 = 5.5

SOIL = soil index determined from five soil types defined by the winter rainfall acceptance potential (WRAP)

= 0.45

SAAR = 1031 mm

RSMD = net one day five year rainfall minus the soil moisture deficit (mm) = 2.48 x √SAAR - 40 = 39.63

LAKE = index of lake area as proportion of total area = 0.005%

Using this method, the 1 in 1 year flow at the culvert becomes:

QBAR = 0.0172 x 21.50.94

x 0.510.27

x 0.451.23

x 39.61.03

x 5.50.16

. (0.995) -0.85

QBAR = 5.61 m3 s

-1

A series of growth factors for flood flows of varying recurrence intervals were determined for Ireland (Cunnane and Lynn,

1975); the Q100 multiplier is 1.96. Other factors applied are factorial error (1.5) and climate change (1.2). Therefore, for the

stream as it passes through the site, the 100-year flood flow becomes:

Q100 = 19.8 m3 s

-1

The two estimates are within 25% of one another and deemed valid. The more up to date FSU estimate of 14.8 m3 s

-1 will be

used in the hydraulic model.

10.9 Hydraulic Model

A hydraulic model was compiled using ISIS software, which was then used to simulate water level at different points along the

River Lear under different flow regimes. The model was compiled using 18 cross sections on the River Lear, the locations of

which are shown in Figure 4. Cross-sectional profiles are presented in Appendix A, with the view looking through the

upgradient to downgradient plane in each case. The node network (the arrangement of cross sections in the model) is

presented in Appendix B.

Manning’s coefficient of 0.035 was used for riverbank sections, with a coefficient of 0.014 applied to culverted sections. The

conveyance capacity of all surveyed cross sections along the stream were assessed for suitability to transmit Q100 flood flows.

The predicted surface water elevations are presented in Table 2.

Due to the lack of gauging station data on the River Lear, the flow on 8th July 2014 was unknown. For the validation

procedure, the flow rate which returned the least difference to observed water levels was 0.2 m3 s

-1. The error range was less

than 0.16 m in the sections upgradient of Lear Bridge. A slightly larger error is observed at the downgradient side of Lear

Bridge. The model was deemed to be valid for the purposes of this assessment, and is deemed to be accurate for the stretch

of river that is the focus of this study.

For the flood simulation, the downgradient boundary condition was taken to be 134 mOD. A high water mark of 132.8 mOD

was observed on the shoreline of Castle Lough but this was considered too low to use as the downgradient boundary.

Flow through current channel

The model predicts that under Q100 flood conditions the sections at the upper end (CS1 and CS2) and lower end of the

surveyed channel (CS16 and CS17) are incapable of transmitting flood flows. These sections are within wider valley landscapes

that weren’t surveyed fully due to overgrowth. These wider valley sections are considered capable of transmitting flood flows.

There are no receptors at risk of flooding in the upgradient section. The creamery activities downgradient of Lear Bridge are

potentially at risk. More detailed surveyed of this stretch and the adjacent fields would be required to quantify this risk more

accurately. Mitigation measures such as a low boundary wall on the southern site boundary of the western site may be

appropriate in this section. The model does not account for any flow diverted from hardstanding in Bailieboro town (which

appears to enter the watercourse via a 1.0 m diameter concrete culvert immediately downgradient of Lear Bridge). This was

outside the remit of the study.

The 3 culverts in parallel (adjacent to the ESB substation) reach capacity during Q100 flows (flood height is 0.12 m above culvert

top). The remainder of the cross section at the upgradient and downgradient ends of these culverts are adequate to transmit

flood flow. Flood flows do not overtop the kerbing that defines hardstanding areas.

Flow through reinstated channel

The simulation shows that under normal conditions, there is a slight increase in river elevation (0.2 m) when the existing

channel is infilled, and the original channel is recommissioned. This is likely due to a slightly smaller cross section in the

original channel (as shown in Appendix A - CS6, CS7, CS8).

Under flood conditions the increase in river elevation through the reinstated channel is estimated as 0.1 m.

In both the current and reinstated channels, the main river channel overtops during flood flows. Flow overtops to the low-

lying field area between the two channels, which acts as a floodplain. This is deemed to be acceptable.

The model shows that there will be no significant difference in river elevation resulting from reinstating the original channel.

Design Flood Levels

The design flood level for the Q100 event in the River Lear as it passes the proposed development area within the site is 135.2

mOD. There is a satisfactory freeboard (clearance) as follows:

• 0.73 m to kerbtop;

• 0.72 m to bund to ESB substation;

• 1.94 m to existing finished floor level.

10.10 Mitigation

The following mitigation measures are proposed:

• maintenance works on the river banks will need to be carried out regularly to ensure the conveyance capacity of the

River Lear is maintained as it passes adjacent to the site. Areas requiring specific attention include the upgradient

side of the culvert as CS10.

• ensure the kerbing that defines the hardstanding on site is continuous, with no missing sections. This is a simple way

to ensure an extra 150 mm protection against flooding.

• any bunding on site should have a minimum top elevation of 135.87 mOD.

• the proposed development removes approximately 68 m2 of existing available flood plain. Whilst this area is

considered marginal, an equivalent flood plain area should be created as part of development works to ensure no

net loss of available flood plain area.

• the model does not show any requirement to increase cross-sectional area of the original channel. However it is

heavily overgrown as shown in Plate 3 below, and the model does not fully account for this vegetation. This channel

needs to be cleaned using an excavator. The conveyance capacity may be increased during cleaning works.

• a summary method statement to cover stream restoration works is presented in Appendix C.

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10.11 Summary

Proposed development works at Bailie Foods require diversion of the River Lear to its original route. This justified the

requirement for a site specific flood risk assessment.

A hydraulic model of the existing River Lear route showed that during 1 in 100 year flood flows, there is no flooding to loca

receptors. A low-lying field adjacent to the riverbank is shown to be

was updated to simulate backfilling of the existing channel and re

increase in surface water elevations during normal or flood flows.

There are no receptors at risk of flooding from the River Lear between the site and Castle Lough. Based on the fact that the

site is not at risk of fluvial flooding the sequential test can be revisited to show that the site lies in a Zone C category.

between the site and the river will not be affected by the development in terms of flood risk. It can be concluded that the

proposed development will not have a negative impact, in terms of flood risk, on the local drainage network, on local private

property, or to the surrounding environment and human health.

10.12 References

Cunnane and Lynn. 1975. Flood estimation following the Flood Studies Report.

DoEHLG, 2008. The Planning System and Flood Risk Management. Department of Environment,

Government, Dublin.

FSR. 1975. Flood Studies Report (in five volumes). NERC, London.

Gardiner, M.J., Radford, T, 1980. Soil associations of Ireland and their land use potential. National Soil Survey of Irelan

Institute of Hydrology. 1993. Flood Studies Report (in five volumes), 3rd binding. Institute of Hydrology, Wallingford.

Nicholson, O. and Bree, T. 2013. The Flood Studies Update

National Hydrology Conference


Plate 3 - Original channel cross section at CS8


requirement for a site specific flood risk assessment. There is no evidence of historical flooding at the site.

A hydraulic model of the existing River Lear route showed that during 1 in 100 year flood flows, there is no flooding to loca

lying field adjacent to the riverbank is shown to become an active flood plain during peak flows. The model

was updated to simulate backfilling of the existing channel and re-opening of the original channel. This showed no significant

increase in surface water elevations during normal or flood flows.

re are no receptors at risk of flooding from the River Lear between the site and Castle Lough. Based on the fact that the

site is not at risk of fluvial flooding the sequential test can be revisited to show that the site lies in a Zone C category.



operty, or to the surrounding environment and human health.

Cunnane and Lynn. 1975. Flood estimation following the Flood Studies Report.

DoEHLG, 2008. The Planning System and Flood Risk Management. Department of Environment,

FSR. 1975. Flood Studies Report (in five volumes). NERC, London.

Gardiner, M.J., Radford, T, 1980. Soil associations of Ireland and their land use potential. National Soil Survey of Irelan

y. 1993. Flood Studies Report (in five volumes), 3rd binding. Institute of Hydrology, Wallingford.

Nicholson, O. and Bree, T. 2013. The Flood Studies Update - What are the improvements since the 1975 Flood Studies Report.

National Hydrology Conference 2013.



There is no evidence of historical flooding at the site.

A hydraulic model of the existing River Lear route showed that during 1 in 100 year flood flows, there is no flooding to local

come an active flood plain during peak flows. The model

opening of the original channel. This showed no significant

re are no receptors at risk of flooding from the River Lear between the site and Castle Lough. Based on the fact that the

site is not at risk of fluvial flooding the sequential test can be revisited to show that the site lies in a Zone C category. The area



DoEHLG, 2008. The Planning System and Flood Risk Management. Department of Environment, Heritage and Local

Gardiner, M.J., Radford, T, 1980. Soil associations of Ireland and their land use potential. National Soil Survey of Ireland.

y. 1993. Flood Studies Report (in five volumes), 3rd binding. Institute of Hydrology, Wallingford.

What are the improvements since the 1975 Flood Studies Report.

OPW, 2009. Report of the Flood Policy Review Group. Office of Public Works, Dublin.

OPW, 2012. The National preliminary flood risk assessment (pfra): Designation of the areas of further assessment. Office of

Public Works, Dublin, March 2012.

Appendices

Appendix A – Cross Sectional Profiles

Appendix B – Node Network

Appendix C – Summary Method Statement for Stream Reinstatement Works

Figures

OPW, 2009. Report of the Flood Policy Review Group. Office of Public Works, Dublin.


Summary Method Statement for Stream Reinstatement Works

158


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Cross Sectional Profiles


Appendix A

Cross Sectional Profiles


CS1

FRA: Lakeland Dairies Co

FRA: Lakeland Dairies Co-Operative Society Ltd. (Bailieboro)

159

Operative Society Ltd. (Bailieboro)

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CS2 FRA: Lakeland Dairies Co-Operative Society Ltd. (Bailieboro)




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Appendix B

Node Network


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Summary

Stream Reinstatement Works


Appendix C

Summary Method Statement for



Method Statement

- River Lear channel re

Prepared for:

Prepared by:

Project Reference No.:

14th

July 2014

INTRODUCTION

The following method statement has been prepared by Colin O’Reilly BAgrSc PhD, of Envirologic Ltd., on behalf of Lakeland Dai

operative Society Ltd. (Bailieboro).

Fisheries Ireland for peer review prior to works commencing.

The method statement intends to describe programme of works relating to re

Bailieboro,

accommodate further development at the Bailie Foods processing facility.

The aim of this programme of works are as follows:

COFFERDAM

A cofferedam will be installed at the northernmost end of the original channel to create a dry working environment. The coff

ensure all waters enter only the existi

low.

A simple earth

positioned on the downstream side of the cofferdam to trap sediment. The earthen cofferdam can be excavated upon completion of

The channel bed can be cleaned and covered with pea gravel following removal of the cofferdam.

Method Statement for


Method Statement

River Lear channel re-alignment @ Bailie Foods, Bailieboro, Co. Cavan

Prepared for: Lakeland Dairies Co-operative Society Ltd. (Bailieboro)

Prepared by: Colin O'Reilly B.Agr.Sc., Ph.D., Envirologic Ltd.

Project Reference No.: 1164

July 2014

INTRODUCTION


operative Society Ltd. (Bailieboro). It shall be made available to Cavan County Council,

Fisheries Ireland for peer review prior to works commencing.

The method statement intends to describe programme of works relating to re

Bailieboro, outlining in broad terms the manner in which the different aspects of the work will be undertaken


aim of this programme of works are as follows:

a) Recommission original channel and divert flow from channel currently in use to original channel;

b) Ensure there is no resulting increase in potential flood risk to upgradient and downgradient receptors;

c) Maximise potential for development of ecological habitat in the recommissioned channel, with a focus on brown trout. This

will include suitability for fish passage, and provision of areas suitable for spawning;

d) Minmise the amount of damage to existing habitat wh

COFFERDAM


ensure all waters enter only the existing channel whilst works are taking place. During low flows the pressure against the cofferdam will be

A simple earth-type cofferdam is deemed suitable given the low depth and low velocity of water in the existing channel. A straw bale will b

itioned on the downstream side of the cofferdam to trap sediment. The earthen cofferdam can be excavated upon completion of


alignment @ Bailie Foods, Bailieboro, Co. Cavan

operative Society Ltd. (Bailieboro)


t shall be made available to Cavan County Council, National Parks and Wildlife Service, and Inland

The method statement intends to describe programme of works relating to re-alignment of the River Lear upstream of the Shercock Road,

outlining in broad terms the manner in which the different aspects of the work will be undertaken. These works are required to


Recommission original channel and divert flow from channel currently in use to original channel;

Ensure there is no resulting increase in potential flood risk to upgradient and downgradient receptors;

e potential for development of ecological habitat in the recommissioned channel, with a focus on brown trout. This

will include suitability for fish passage, and provision of areas suitable for spawning;

Minmise the amount of damage to existing habitat when diverting flow from channel currently in use to original channel.


ng channel whilst works are taking place. During low flows the pressure against the cofferdam will be

type cofferdam is deemed suitable given the low depth and low velocity of water in the existing channel. A straw bale will b

itioned on the downstream side of the cofferdam to trap sediment. The earthen cofferdam can be excavated upon completion of


165

The following method statement has been prepared by Colin O’Reilly BAgrSc PhD, of Envirologic Ltd., on behalf of Lakeland Dairies Co-

National Parks and Wildlife Service, and Inland

er Lear upstream of the Shercock Road,

. These works are required to

e potential for development of ecological habitat in the recommissioned channel, with a focus on brown trout. This

en diverting flow from channel currently in use to original channel.

A cofferedam will be installed at the northernmost end of the original channel to create a dry working environment. The cofferdam will

ng channel whilst works are taking place. During low flows the pressure against the cofferdam will be

type cofferdam is deemed suitable given the low depth and low velocity of water in the existing channel. A straw bale will be

itioned on the downstream side of the cofferdam to trap sediment. The earthen cofferdam can be excavated upon completion of works.

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CLEANING ORIGINAL CHANNEL

The banks and bed of the original channel are heavily overgrown and require cleaning. This is necessary to ensure the cross sectional area

provides adequate conveyance capacity to transmit flood flows. All vegetation and excess silt in the original channel will be removed using an

excavator.

Material removed from the channel will be used to increase bank height on the western side of the stream.

It is acknowledged that there will be a temporary adverse impact to habitat associated with the removal of this vegetation. Once new

vegetation is established, the longer term impact will be positive.

CHANNEL ROUTE

There will be no straight sections in the recommissioned route, which is approximately 200 m in length. The gradient across the channel route

is very low which limits the potential of introducing oxygen to the stream by way of cascades and turbulent zones. Velocity, and turbulence,

can be increased slightly at minor narrowed sections in the low flow channel, as per Figure 1.

Rows of larger stones/boulders will be placed on the stream bed in flatter sections to creat riffles. The channel will be deepened on the outer

side of any bends to create pools.

The upgradient invert of the existing culvert shall be submerged to a depth of 300 mm during low flow conditions. This was confirmed during

recent site visit.

Figure 1 – Narrow river channel in low flow (IFI & OPW, 2010)

CHANNEL CROSS SECTION

The width of the river channel will be reduced from the river bed to a height of 300 mm. This reduced width will be around 0.5 – 1.0 m. This

has the effect of maintaining higher velocities in the wetted channel during normal and low flow regimes. The upper section of the profile will

be wider, to provide a conveyance capacity capable of transmitting flood flows. A schematic is presented in Figure 2. The exact channel

dimensions will be confirmed following completion of flood risk assessment.

Figure 2 – Schematic of stream cross sectional profile (ERFB, 2011)

The inside of channel bends will be landscaped with sloping marginal benches, as shown in Figures 3 and 4.

Figure 3 – Channel bend cross section

Figure 4 – Channel bend cross section

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CHANNEL BED

The stream bed will be covered with a 200 mm depth of clean (i.e. washed), smooth, rounded, pea gravel (less than 10 mm diameter). This

will help to promote the formation of gravel riffles which make suitable spawning grounds for brown trout (see example in Figure 5). Gravel

will be deposited onto the river bed using an excavator. Boulders shall be spaced out intermittently along the low flow channel.

Figure 5 – Gravel bed

CHANNEL BANK VEGETATION

Any excavated soils will be stockpiled temporarily and used to cap the banks of the rehabilitated channel. This will promote establishment of

vegetation.

The rehabilitated channel bank will be planted with native species that can be controlled/maintained to ensure conveyance capacity of

channel is not significantly reduced by overgrowth in future. Grass and juvenile, native trees are deemed suitable. Trees will provide cover to

pooled sections of the river channel.

Gradients should be such that no bank failure or slippages will occur in future.

CHANNEL OPENING

Works on the original channel will commence at the southernmost end, and proceed northwards. Once the original channel has been fully

restored, the eastern bank of the current channel will be opened to allow water entry.

The final section to be removed, i.e. the cofferdam, will be used to dam the existing channel in the same way and to full bank height. The

current channel will then be infilled.

HYDROCARBONS

Hydrocarbon spill kits will be on-site during works. Any fuels and lubricants will be stored in bunded compounds. Refuelling will be carried

out safely and securely away from the river environs. Machinery will be fully inspected prior to, and during, the course of works for suitability.

Support vehicles will remain on the tarmac / hard-core roadway.

The work area will be accessed from the hard-core roadway adjacent to the ESB substation. There will be no machinery in the stream

channel.

There will be no use of concrete or cement during restoration works.

TIMING OF WORKS

All works within the river channel shall be carried out between the months of August to September 2014, to coincide with low stream flows

and to avoid interference with spawning runs.

No tree cutting works are proposed. Bank maintenance works further upstream would be beneficial. This would primarily involve the

removal of scrub. These works should take place between October and March.

Following opening of the original channel, water flow will be maintained in the current channel for a minimum period of 24 hours, to facilitate

downstream migration of any insects/fish. Water supply will be from a fire hydrant located next to the existing channel.

FRESHWATER PEARL MUSSELS

Standard precautionary measures to be practiced for protection against risk of invasive species, particularly freshwater pearl mussels. Any

machinery, including excavator and dumper will be cleaned with a pressure washer prior to arriving on site, and upon leaving site.

References

ERFB, 2011. Requirements for the protection of fisheries habitat during construction and development works at river sites. Eastern Regional

Fisheries Board.

IFI, OPW, 2010. The Environmental River Enhancement Programme. Inland Fisheries Ireland and Office of Public Works.

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Fig .1 - Surface Water Catchment Map

Fig .2 - Regional Surface Water Levels

Fig .3 - Local Surface Water Levels

Fig .4 - Cross Section Locations Maps

Fig .5 - Channel Re


Figures

Surface Water Catchment Map

Regional Surface Water Levels

Local Surface Water Levels

Cross Section Locations Maps

Channel Re-Alignment


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