Hydrological Assessment Report
Commissioned by
An Bord Pleanàla
with respect to
PW 3005 / JA0030
Lough Ennell Water Abstraction to Royal Canal
Consultant Dr. Pamela Bartley
August 2012 Hydro-G
50 Henry St.
Galway
091 449950
087 8072744
Project No.: 09245_L Ennell_RC
Report Status: Final_3
Report Title: An Bord Pleanàla, Westmeath County Council’s proposed abstraction from Lough Ennell to the Royal Canal.
Date: 27th August 2012
Prepared by: ______
Dr. Pamela Bartley
NOTES:
This report is for the use solely of the party to whom it is addressed and no responsibility is accepted to any third party.
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TABLE OF CONTENTS
1. Introduction ------1
2. Methodology ------2 2.1. Assessment of Information ------2 2.2. Request for Further Information & Assessment of Response ------2 2.3. Site Visit & Catchment Assessment ------2 2.4. Hydrological Information of Significance obtained at Oral Hearing------3
3. Hydro-G’s Evaluation of the Proposal ------4
4. Addressing Hydrological Concerns Expressed in Written & Oral Submissions -- 14
5. Conclusions ------16
References ------17
Appendix A Hydro-G’s Hydrological Calculations------18
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1. Introduction
Westmeath County Council made a proposal to take a supply of raw water from Lough Ennell at Ladestown, Mullingar to supply the Royal Canal. Objections were made to this proposal and were not withdrawn. Westmeath County Council then applied to An Bord Pleanàla for a Provisional Order declaring that their proposal come into force (WCC letter to An Bord Pleanàla dated 7 th December 2011). There are two An Bord Pleanàla references to this case: PW3005 relating to the EIS application and JA0030 relating to the abstraction order. The hydrological issues are the same and are dealt with in an integrated manner in my report.
My hydrological report is intended to aid An Bord Pleanàla in their assessment of the proposed Lough Ennell abstraction supply to the Royal Canal in that it provides expert opinion on the water aspects of the proposal. In addition to consideration of the hydrological implications of the abstraction, I have considered the potential of the proposal to affect the hydrogeological regime feeding dependent terrestrial habitats in the vicinity of Lough Ennell and the feeder stream from Lough Owel. For details relating to the proposal, readers are referred to the EIS and NIS accompanying the proposal by Westmeath County Council to abstract water from Lough Ennell, Co. Westmeath to supply the Royal Canal. An Bord Pleanàla has commissioned additional expert advice from an ecologist, Dr. Evelyn Moorkens. This hydrological report is intended to also aid the ecological assessment and readers are referred to Dr. Moorken’s report (August, 2012) for ecological details and independent ecological assessment.
The aims of my independent hydrological assessment and report are as follows:
a) Evaluate and comment on the justification and rationale for the Abstraction Order;
b) To assess the validity of the approach to hydrological assessment undertaken;
c) Outline and comment on the potential changes to the hydrology as we now understand it;
d) To assess the consequences for water quality, if any;
e) To provide a statement regarding the proposal and how it fits with the requirements of the Water Framework Directive;
f) Comment on potential impacts in affected watercourses in terms of different hydrological regimes such as low flows and floods;
g) Evaluate the proposed regulation of abstractions and flow from Lough Ennell and provide advice regarding the required conditions that should be attached to the sanctioning of the proposal, should that sanction be warranted;
h) Evaluate the proposals for the installation/construction phase and pipe design.
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2. Methodology
2.1. Assessment of Information
My initial assessment was informed by the application documentation, including the submitted EIS and Appropriate Assessment Report and submissions received from prescribed bodies and third parties. In addition, I relied upon my civil engineering background and knowledge of hydrology, hydrogeology, eco-hydrology, and groundwater dependent environments. I employed Irish research findings and nationally available datasets for hydrometric and hydrochemical details of significance to the proposal.
2.2. Request for Further Information & Assessment of Response
Given the interdependency of the water and ecological aspects of the proposal, I worked in collaboration with Dr. Moorkens in an assessment of the EIS and other case information and we determined that there were deficits in the information supplied, which prevented an integrated hydro-ecological, macro scale, evaluation of the proposal. Therefore, a request for further information was issued by An Bord Pleanàla (March, 2012).
Two written responses to the further information (10th April and 30th April) were received by An Bord Pleanàla and these were reviewed by the inspector responsible for this case (Ms. Mairead Kenny), Dr. Moorkens and I. The responses to the further information did not provide the additional information that I needed to complete my assessment of the sureness of the conclusions that could be drawn regarding the simulated hydrological regime that would result from the proposal, potential changes to the lake shore wetting extents and the consequent effects on groundwater dependent terrestrial ecosystems e.g. the designated Alkaline fens. The responses did not provide the details requested to support an independent analysis of hydrological changes in Lough Ennell. Drawings were submitted as requested but not at a suitable scale to facilitate my alternative assessment of impacts and changes of wetting extents of the lake, some items were partially answered with as much detail as the applicant “considered relevant”, items 8, 10, 11, 13, and 16 were not answered and items 5 and 16 both suggested a operation/management strategy that did not comply with the obligations of Statutory Instrument S.I. No. 477 of 2011 (European Communities (Birds and Natural Habitats) Regulations 2011). Further, the conclusions drawn from the hydrological simulation outputs were difficult to rationalise. The oral hearing arranged provided an opportunity to clarify many aspects of the proposal.
2.3. Site Visit & Catchment Assessment
Upon receipt of the Further Information and in light of the information deficits, Ms. Mairead Kenny, Dr. Evelyn Moorkens and I visited the site and the catchments of each Lough Ennell & Lough Owel on the 9 th May 2012. During a visual assessment of the catchment, I noted general catchment characteristics, hydrological patterns and anthropogenic pressures. I also recorded -2-
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Ms. Mairead Kenny, Dr. Evelyn Moorkens and I visited the site of the Clonsingle weir on the 21 st May 2012. It became obvious during our site visit that the central section wooden gate at Clonsingle was dysfunctional. At the oral hearing it was further determined that the current state of the weir was that control was not possible. In addition, we noted during our site visit that the turbulence downstream of the weir would appear to create a problematic environment for fish passage. We also made observations in the pattern of drainage and the disrepair of control structures on the Monaghanstown stream in the vicinity of Lough Ennell. Information gained in the catchment greatly filled knowledge gaps and provided physical context for information and clarifications that would be sought at the proposed oral hearing.
2.4. Hydrological Information of Significance obtained at Oral Hearing
The information gained at the oral hearing clarified all my issues regarding hydrology and the proposed regimes for both the abstraction and discharge from Lough Ennell, and the consequent potential effects. The most significant pieces of hydrological information gained at the oral hearing were as follows:
o That there is currently no control of or regulation of water levels in the lake. Water flows from Lough Ennell through the Clonsingle weir with no control of discharge from Lough Ennell to the River Brosna. o The uncontrolled discharge condition is further exasperated by the fact that the River Brosna acts as an enhanced drainage mechanism for Lough Ennell because of the drainage works deepening of the Brosna’s channel carried out by the OPW on the River Brosna in the 1950’s. o As part of the proposal by Westmeath County Council (WCC), to use Lough Ennell as a source of water for supply to the Royal Canal, it is proposed to refurbish the existing Clonsingle weir and in the process they will install a remote controlled gate.
The missing piece of information, prior to the hearing, was that there is currently no control of discharge from the lake. It is this aspect of the proposal that supports the conclusions drawn that an abstraction is feasible because they are going to stop the uncontrolled draining of the lake and instead use this water for their purpose of supplying water to the Royal Canal. The proposal is stated in the EIS as follows: “As part of this abstraction scheme, it is proposed to replace the existing vertical sluice gate with an automatic overshot gate which would allow full control of the lake levels and a continuous record of the outflow from Lough Ennell. The proposed sluice gate upgrade would significantly improve the existing situation of water level control at the outlet.” (EIS, September 2011, Vol 2, Page 104, RPS).” It is my opinion that the words “ significantly improve ” presented in the EIS did not convey the fact that there is currently no control and that the water currently lost from the lake will be retained and harvested for the Royal Canal.
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3. Hydro-G’s Evaluation of the Proposal
The context facilitating conclusion on the hydrological assessment rests on the most significant hydrological revelation of the oral hearing, which is that there is currently no control of discharge from the lake. The abstraction, for the purposes of supplying the Royal Canal, becomes feasible by the implementation of control of the discharge from the lake.
The aims of the independent hydrological assessment and report were as outlined in Section 1, and I now present my responses to each of the stated aims as follows:
a) Evaluate and comment on the justification and rationale for the Abstraction Order;
The obligation on Westmeath County Council to provide water for the Royal Canal has been clearly outlined in all documentation accompanying this case before An Bord Pleanàla. The requirement and legal obligation on Westmeath County Council to supply water to the Royal Canal was again clearly outlined in the opening statements of the Oral Hearing. Lough Owel is the current source of water for supply to The Royal Canal. Calculations and experience in recent years demonstrate that there is excessive pressure on the available water volumes in Lough Owel because it is currently relied upon to provide water to the population of Mullingar, the fish farm at Cullion and The Royal Canal. It is noted that the Royal Canal has only re-opened in the last number of years and therefore it is a recent increased pressure on Lough Owel. Lough Owel is also a designated European Site and important recreational resource. Justification for an abstraction from Lough Ennell has been presented in the context of water resources available in Westmeath County and water volumes within practical distance of the Royal Canal’s summit level;
The ‘Opening Statement’ of the Oral Hearing, presented by Mr. Mc Mullen (Solicitor) on behalf of Westmeath County Council, provides the legal rationale for their seeking of this “Provisional Order for the Lough Ennell Water Abstraction pursuant to the Water Supplies Act, 1942 as amended by the Water Services Act, 2007 and the Planning & Development Act 2000”;
The proposal (Abstraction Order application) to use Lough Ennell as the source of water for the Royal Canal was supported by an EIS. I conclude that the proposal is hydrologicaly justified on the following basis:
The evidence given at the Oral Hearing and the discussions that ensued between those representing An Bord Pleanàla and the applicant and its consultants, those who made written and oral submissions with respect to the application and persons at the hearing representing Prescribed Bodies such as NPWS and Inland Fisheries Ireland;
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The supporting background reports and additional information that was supplied by Waterways Ireland. An Bord Pleanàla, in its written requests for Further Information, had requested copies of all ESBI and RPS reports that had been created in the Investigation of Additional Water Supplies for the Royal Canal. However, the responses to Further Information were not accompanied with complete copies of the reports requested. At the Oral Hearing, An Bord Pleanàla initiated discussions that concerned details contained in these reports and Waterways Ireland subsequently obtained complete copies and delivered four number reports on the second day of the Oral Hearing (ESBI, 1998; ESBI, 2005; ESBI, 2009 and Waterways Ireland, 2004). These reports provided useful information that aids my conclusion that the proposal to use Lough Ennell as the water supply source is the most justifiable source. The proposal is further supported by explanations, by Mr. Nigel Russell, Director of Services for Waterways Ireland, relating to their experiences in recent operation of the Royal Canal, his assessment of the potential significance of other water inputs, the influence of the natural terrain through which the Royal Canal is constructed and attempts to repair leakages.
Overall I conclude that given that the proposers have calculated that Lough Ennell has the reservoir storage available to supply the water volumes required for the Royal Canal, the carbon footprint of infrastructure and future energy costs associated with the alternatives investigated suggest that Lough Ennell is the most justified source at present. The applicant has now supplied enough information to support the proposal that Lough Ennell can supply water within a justifiable range of lake water levels and has requested the sanction for an ‘operate and evaluate’ strategy by management committee. Waterways Ireland have heavily invested in ESBI’s analyses of water supply for the Royal Canal and the reports (ESBI, 1998 – 2009) detail alternatives that are available, albeit less favoured. These alternatives shall be available in the future if practical, operational experience in the abstraction from Lough Ennell is evaluated to either
(a) Result in a negative impact, in terms of its designation as a European Site,
or
(b) Fail to satisfy the requirements of the Royal Canal.
For now, the information suggests that Lough Ennell has the hydrological capacity to supply the Royal Canal and maintain water levels within the historical range of water levels recorded at the lake. Dr. Moorkens (August, 2012) shall address ecological issues and assessments.
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b) To assess the validity of the approach to hydrological assessment undertaken; o I conclude that the hydrological calculation methodology is valid, and the assessment conclusions drawn are justifiable, now that we have established the following:
o That Lough Ennell has the reservoir storage capacity for most/average scenarios and that it will have even more reservoir storage capacity by the proposed reconstruction and automation of the sluice gate control at the Clonsingle weir; and
o That the minimum water level proposed can be controlled and that the specification of a maximum level is a design aspiration because Lough Ennell’s water levels, in reality, can overspill the actual crest level at Clonsingle weir at whatever height the upgradient recharge feeding the lake system dictates. Therefore, maximum water levels will be as nature dictates and trends will be as naturally experienced historical lake levels.
c) Outline and comment on the potential changes to the hydrology as we now understand it; o Discussions that ensued, during the formal proceedings of the hearing, between myself and Mr. Tom Quigley of RPS allowed me to have confidence that the viability of the proposal to extract water from Lough Ennell for supply of water to the Royal Canal is dependent upon proper management and control of the weir at the existing structure of the weir at Clonsingle. This weir is currently not in efficient function or any function really. It is a physical structure but no weir control is possible at the moment. The current weir is in disrepair and the middle control gate requires manual manipulation, if manipulation is even possible. Part of the proposal involves re-engineering of the weir. It has now been clarified that the abstraction volumes proposed in the RPS submission will result in a range of water levels that is within the range currently experienced by the site. This clarified issues causing hydrological confusion in the EIS.
o In the course of the hearing I collated the values and range of water levels historically experienced and those proposed. This pictorial, hand drawn representation was circulated to all parties in the oral hearing demonstrates that the proposed operating range is within the levels experienced and that the minimum water level proposed will result in more water in the lake than historically experienced during low flow conditions. This provides the basis for most of the assessments required.
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o There was some confusion regarding a proposed minimum water level of 78.487m OD (Malin) in the submission and paper copy of an email dated 16 th May 2012, time 15:28) presented by Mr. David Hogan, Director of Services, WCC. It is clear from my pictorial, hand drawn representation of collated values, and range of water levels historically experienced and those proposed, that this 78.487m OD (Malin) level is lower than that presented by the consultants acting for WCC and is lower than the historical minimum level recorded at the lake. However, Mr. David Hogan subsequently confirmed that WCC would accept and adhere to any conditioned minimum water level that An Bord Pleanàla deems appropriate. Therefore, I suggest that at this stage, with the information that the consultants for WCC could mathematically support, An Bord Pleanàla should consider, for the purposes of Appropriate Assessment, 79.146 m OD as the minimum water level envisaged at the Clonsingle weir, and consequently in Lough Ennell. This is the simulated minimum water level to which the water level shall drop to whilst supporting fish pass flows of 0.29m3/s following cessation of abstraction, for the purposes of supply of water to the Royal Canal, at the main weir crest level of 79.325 m OD Malin.
o It has been determined that the alkaline fens are of a topographical elevation that related to lake water levels prior to the OPW’s drainage works in the 1950’s and therefore these habitats have existed within the range of water levels proposed and are not dependent upon flooding at the extreme water levels. In addition, I have assessed that the proposal does not have potential to affect groundwater delivery to these systems.
d) To assess the consequences for water quality, if any; o The proposal presents a reduced threat for nutrient enrichment compared to the unregulated minimum water level, as is the current situation. The proposal to regulate water retention in Lough Ennell means that there will be more water in the Lake and therefore less potential for enrichment. Nutrient mass loading to the lake will remain the same but there will be more water in the Lake and therefore enrichment potential is reduced.
o The proposal does not have the potential to negatively affect the assimilation capacity of Lough Ennell because the proposed operating range is within the levels experienced and that the minimum water level proposed will result in more water in the lake than historically experienced during low flow conditions. There is, therefore, no potential for impact or deterioration in ‘Status’.
o Further discussions, during the formal proceedings of the hearing, on the evidence by Dr. William O Connor relating to the hydrology of the River Brosna provided justification for the inferred conclusions previously presented in the EIS. I have
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independently assessed the DWF and other hydrological characteristics of the River Brosna and I am satisfied that the proposal shall not deleteriously affect long term water quality in the downstream receptors. A minimum compensation flow of 0.29m3/sec, which will be maintained in the fish pass rate, concurs with the existing minimum flow condition expected for the River Brosna immediately downstream of Lough Ennell (determined by interpolation of contributing areas, OPW data and EPA HydroTOOL data).
o With respect to the facts that water delivered to the Royal Canal will now be from Lough Ennell rather than Lough Owel and that the latter, historical source, has a better water ‘status’ than Lough Ennell, my assessment is that ‘status’ is comprised of many components – not just hydrochemical quality of water. Therefore, I suggest that the Royal Canal’s quality shall not be compromised because the proposed control of Lough Ennell and the consequent improvements in water quality that shall eventually result in a water quality not hydrochemically dissimilar to that supplied from Lough Owel.
e) To provide a statement regarding the proposal and how it fits with the requirements of the Water Framework Directive; o www.wfdireland.ie suggests that Lough Owel (IE_SH_26_703) = Good Status and that Lough Ennell (IE_SH_25_188) = Moderate Status, restore 2021.
o The proposed operating range is within the levels historically experienced and the minimum water level proposed will result in more water in the Lough Ennell than historically experienced during low flow conditions. There is, therefore, no potential for impact or deterioration in ‘Status’. The proposal actually presents opportunity to improve water quality in Lough Ennell and therefore will assist the WFD objective to ‘restore’.
f) Comment on potential impacts in affected watercourses in terms of different hydrological regimes such as low flows and floods; o I suggest that the applicant has demonstrated by mathematical calculations presented by Mr. Quigley, that the control of the weir at Clonsingle is feasible, abstraction of water for the Royal Canal is sustainable and shall result in a water level range between 79.471 m OD (max) and 79.146 m OD (min).
o Given that the proposed operating range of 79.471 m OD (max) to 79.146 m OD (min) level is within the range currently experienced, it is envisaged that there is no potential to create a negative impact. The proposed 79.146 m OD minimum -8-
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water level value is greater than the historically observed minimum. It is this low flow condition that poses the anthropogenic threat to the water dependent features of interest. Therefore, in principle, the proposal presents a positive scenario for the low flow condition. The high flow condition is dictated by nature and rainfall.
o Under the proposed management regime, the minimum water level will be similar to those levels experienced in the most recent datasets presented for 2010. Therefore, the applicant has dispelled my concerns that the abstraction proposal would have potential to cause some areas of the lake margin and their associated protected habitats to dry out. Discussions at the oral hearing allowed me to determine that there was no potential to cause change or deterioration when operating within the proposed range of water levels at Clonsingle weir of 79.471 m OD (max) to 79.146 m OD (min).
o By holding back water behind Clonsingle weir, but allowing a minimum compensation flow of 0.29m3/s through for fish pass, WCC and their consultants have determined that they can supply the Royal Canal with the water required, on an average calculation basis. Consideration of the significance of the term ’average’ is important. In the course of discussions during the formal sessions of the oral hearing it was fully explained and demonstrated how the supply volume is sustainable, there is no question that the volume of water is available in Lough Ennell, on average. However, not only have we now confirmed that the volume of water is available, they have presented a justifiable set of water levels (min and max) that are associated with the abstraction volumes. Numerous ecological consultants for the applicant provided rationale for support of the range of water levels at Clonsingle weir of 79.471 m OD (max) to 79.146 m OD (min). Discussions facilitated hydrological acceptance of the presented methodology modelling the hydrological flow through the system. Accounting for the abstraction volume ranges expected, they have presented a range of expected water levels and have demonstrated mathematically that Lough Ennell can act as a source of supply to the Royal Canal.
o While they have specified a maximum expected water level of the expected operating range, we have determined, by discussion and evaluation during oral hearing, that it is not possible to specify what the maximum level will be because weather conditions will dictate the maximum water level. An Bord Pleanàla should not be concerned that the maximum water level value cannot be defined. The maximum water level will be whatever the elements determine it to be. That is the lake’s natural system.
o It is the minimum water level that is of critical significance to the lake habitat, protected species etc. The applicant has now provided enough evidence and demonstrated, with information presented at the oral hearing, that the minimum -9-
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water level expected is 79.146 m OD: This level is ~0.3 m higher than the minimum water level than has been experienced during lowest flow conditions at the site in the last ten years – this is good for the lake, and it is ~0.5m higher than the 60 yr historical minimum observed (1956). Numerous ecologists for the applicant and national stakeholders NPWS confirmed that the proposed regulation of the lake would be a good thing in that it afforded more stability in the habitats and returned the lake to a more natural type of lake condition. The proposed narrowing of the annual fluctuation range from the ~1m current/historical experience range to the proposed ~0.3m simulated range means that the lake extent will never be smaller than is currently experienced and it will retain its maximum flow condition/inundation characteristic also. In addition to the positive aspects of this proposed regulation on lake quality and its designated species and habitats, I assess this to be good for the groundwater dependent terrestrial ecosystems (GWDTEs) in the vicinity of and on the lake margins. From a hydrogeological perspective, it is most likely that the groundwater flow characteristic of the GWDTEs will be stabilised by the proposed regime.
o I have calculated that with respect to worst case hydrological scenarios, the volume of water stored in Lough Ennell shall facilitate flows to the River Brosna as follows:
based on the operating range of water abstraction ceasing at the 79.325 m OD Malin crest level and for no input of any water to Lough Ennell under a drought scenario, the envisaged 79.146 m OD Malin minimum level will facilitate maintenance of the fish pass flow proposed (0.29 m3/s) to be sustained for >60 consecutive days;
based on the operating range of water abstraction ceasing at the 79.325 m OD Malin crest level and for no input of any water to Lough Ennell under a drought scenario, the maintenance of the fish pass flow proposed (0.29 m3/s) could be sustained for >250 consecutive days if water levels in Lough Ennell dropped to the minimum recorded level (1956);
based on there being no rainfall and influent streamflow contributions to Lough Ennell from a starting point of the maximum proposed operating level of 79.471 m OD Malin, the maintenance of the fish pass flow proposed (0.29 m3/s) could be sustained for >350 consecutive days;
The above calculations are purely to demonstrate that proposal before An Bord Pleanàla is justifiable, hydrologicaly, in that the number of days scenario in which there would be no influent flows to Lough Ennell is unlikely ever to be 60 consecutive days.
o With respect to potential for flooding downstream in the River Brosna, Dr. William O Connor provided evidence that alleviated my hydrological concerns. In summary, the River Brosna has an artificial cross-section, the river has been
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deepened, the flow and characteristic of the habitat and species has been altered already. The proposal does not have potential to cause deterioration in its ecology or status.
o The flow through the Clonsingle weir is not controlled at all now. The regulation of the weir, as proposed, will still allow enough water down the system. The proposers were adamant that the fish pass flow rate (0.29m3/s) and Denil type fish pass is appropriate for our river systems in this country. While IFI initially expressed serious concern regarding fish pass design, by the end of the discussions conducted during the oral hearing IFI appeared to be more or less in agreement with the proposals. They expected that, by the end of their planned negotiations and discussions with WCC, they would arrive at a workable solution. In any case the weir will be subject to ministerial review prior to its approval and IFI have scope for dictating requirements in this regard.
g) Evaluate the proposed regulation of abstractions and flow from Lough Ennell and provide advice regarding the required conditions that should be attached to the sanctioning of the proposal, should that sanction be warranted;
o I suggest that the applicant has demonstrated by the mathematical calculations presented by Mr. Tom Quigley, of RPS consulting engineers acting for the applicant, that the control of the weir at Clonsingle is feasible and the abstraction of water for the Royal Canal is sustainable. The minimum lake water level at Clonsingle is simulated to be 79.146 m OD. However, the EIS main Report (RPS, EIS, Vol. 2., page 47, 2011) states that “the simulation assumes that only fish pass flows are allowed out of Lough Ennell once the water level drops below the main weir crest”. The same point is presented in that EIS on pages 46 and 48. Therefore, I suggest that An Bord Pleanàla explicitly inserts a Condition that the abstraction of water from Lough Ennell to supply the Royal Canal must cease once the water level in Lough Ennell drops below the main weir crest level: that is 79.325 m OD water level. Upon recovery of water levels to levels greater than the Clonsingle weir crest level, i.e. >79.325 m OD Malin, pumping to the Royal Canal from Lough Ennell can recommence. This must be a condition of the abstraction order. Otherwise, there is potential for damage to the European Site in the absence of operational information. Upon cessation of abstraction when water levels drop below the main weir crest level, Lough Ennell then has capacity for further lowering of water levels to the scientifically supported proposed simulated minimum water level of 79.146 m OD in order to maintain minimum fish pass flows to the River Brosna. WCC & NPWS have each acknowledged that it is only by Management Committee and experience that the correct sluice gate management programme can be put in place. However, it would have been contrary to the requirements of the Habitats Regulations 2011 for An Bord -11-
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Pleanàla to allow an abstraction volume without a condition on the minimum water level value that has been proven to not have potential for damage. The applicant/IFI/NPWS/WI have agreed to establish a Management Committee and work collaboratively to manage the water levels and responses in the lake, charophytes, effects on the alkaline fens etc. By conditioning the water level at which abstraction must cease (i.e. 79.325 m OD at Clonsingle Weir), An Bord Pleanàla can have comfort in the fact that it has been demonstrated by calculation that the abstraction associated with that water level is feasible and sustainable. I have provided some mathematical validation in Appendix A to support the practicality and feasibility for the Condition to cease abstraction at the water level of 79.325 m OD at Clonsingle Weir.
o What would be the effect on the ability of the Royal Canal to stay open if pumping must cease on certain days? This question could not be answered by the applicant, Waterways Ireland or any of the applicant’s consultants. By limiting permission to abstract only when Lough Ennell’s water level is at or greater than crest level at Clonsingle weir we are facilitating the proposal’s request to allow a Management Committee to operate and manage the system and we are also adhering to our obligations with respect to the Habitats Regulations 2011.
o Useful information was supplied by Mr. Greg Duggan, Senior Engineer (WCC) when he provided justification that Lough Ennell did not have to be the only source of water to the Royal Canal in the future because Lough Owel could have capacity again if there was an alleviation of public water abstraction reliance from Lough Owel in the future. He explained the public water supply sources in Westmeath and he outlined that with respect to alleviating public water supply abstraction pressure on Lough Owel in the future, WCC has approval for and the ability to implement the Killinure Lough abstraction. It was also suggested that the Shannon/Dublin Scheme may also provide some public water supply and relief in the future. It was also confirmed by WCC that the existing feeder from Lough Owel shall continue to be operational and WCC will guarantee a volume of 0.5MGD (0.026m3/s) down that feeder. In this way, the hydraulic connectivity between Lough Owel and the Royal Canal is maintained and the ecological interests in the lands in the vicinity of the feeder are sustained.
o I therefore determine that the scheme is justified: public water supply from Lough Owel to Mullingar is ensured and by the time that the Lough Ennell abstraction has been managed by the proposed management committee for a season or two, WCC has the approvals and funding to implement the Killinure scheme and the relief of pressure on Lough Owel shall be such that any shortfall or low flow days in which the gates at the Clonsingle weir downstream of Lough Ennell have been closed and supply from Lough Ennell to the Royal Canal has ceased – at that stage, the gravity fed feeder from Lough Owel can be re-engaged if necessary in order to continue to sustain the Royal Canal. -12-
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h) Evaluate the proposals for the installation/construction phase and pipe design;
o Proposals as per information provided in the EIS, September 2011, Volume 2, Page 15, “3.3 Proposed Works” are acceptable.
o In oral evidence, Mr. Kevin O’Sullivan, of RPS on behalf of Westmeath County Council, confirmed that with respect to “ Intake works ”: 1) The laying of pipeline will not involve piling in the lake bed; 2) During the horizontal drilling proposed for the pipeline, control of sediment will be carefully considered; and 3) The use of bentonite slurries will not be compulsory to aid drilling progression and keep the drill hole open. Therefore, our concerns regarding breakthrough of bentonite in lake water when the drill hole emerges at the intake point within the lake are allayed. NPWS further commented at the oral hearing that it was not concerned with the use of bentonite due to the inert nature of the material.
I suggest that it is important that a dewatering pump will be onsite during the construction phase so that, if an emergency arises during drilling, there will be no delay in pumping sediment laden waters to appropriate areas at the land surface.
o With respect to “ Lake Outlet Modifications ”: The proposed outlet modifications will be carried out at Clonsingle are acceptable.
o With respect to the “Fish Pass”: As previously stated, The fish pass flow rate (0.29m3/s) and Denil type pass is appropriate for our river systems in this country. While initially concerned, by the end of the discussions conducted during the hearing IFI appeared to be more or less in agreement with the proposals and expect that by the end of the discussions, that their planned meeting and negotiations with WCC would arrive at a workable solution – in any case the weir will be subject to ministerial review prior to its approval and IFI have scope for dictating requirements in this regard.
o With respect to “River Flow Measurement” : from a civil engineering/hydrological perspective, the proposals are acceptable. However, the ecological considerations shall be addressed by Dr. Moorkens.
o With respect to modifications proposed for the Monaghanstown stream from a hydrological perspective, the proposals are acceptable in that the purpose, as expanded on in oral hearing evidence of Mr. Kevin O’Sullivan, of RPS on behalf of Westmeath County Council, is to add to the hydrological volume at the Clonsingle stream. The IFI have raised concerns over reversal of flow in the Monaghanstown stream. Ecological and fish life considerations shall be addressed by Dr. Moorkens.
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4. Addressing Hydrological Concerns Expressed in Written & Oral Submissions
Written objections and submissions were received by both Westmeath County Council (2011) and An Bord Pleanàla (2012). Erry Mills had lodged a written objection to Westmeath County Council (2011) and they verbally expanded on their concerns to An Bord Pleanàla at the oral hearing.
I assess that the majority of concerns raised in submissions by objectors are appeased by the same fact that facilitated my conclusion on the hydrological assessment. It was the most significant hydrological revelation of the oral hearing: that there is currently no control of discharge from the lake. The abstraction, for the purposes of supplying the Royal Canal, becomes feasible by the implementation of control of the discharge from the lake. The proposed re-engineering of the control at Clonsingle weir shall alleviate the historical low lake levels cited by many objectors. I have detailed, in Section 3 of my report, how the proposal shall also create a situation that should alleviate the nutrient enrichment in Lough Ennell, which is a common thread in many objections. Westmeath County Council addressed each of the objector’s concerns in a letter (signed by Mr. Hugh O Reilly, Director of Services, Water Services & Environment) addressed to An Bord Pleanàla, dated 6 th December 2012 (sic), which we assume to be dated 6 th December 2011. I support the calculations and opinion presented. I offer that it was not clear prior to the oral hearing that there was currently no control on discharge from Lough Ennell and that the deepening of the channel of the River Brosna, downstream of Lough Ennell had exasperated drainage flow from Lough Ennell.
The written submission of the EPA (dated 3 rd February, 2012) to An Bord Pleanàla makes many suggestions and recommendations regarding how the assessment could have been improved upon with more detail and clarity but the EPA essentially concludes that Lough Ennell can support the abstraction if a careful management regime is imposed. I have detailed the main obligation in water level range control to be assigned to the management committee in Section 3 (g) of this report and further discuss in the next paragraph. I also reference the EPA’s Hydrological Evaluation and other comments in my hydrological calculations presented in Appendix A.
The written submission of the Department of Arts, Heritage and the Gaeltacht (dated 25 th November, 2011) focuses on ecological and archaeological rather than hydrological issues. Therefore, I refer readers to the ecologist’s report on behalf of An Bord Pleanàla (Moorkens, 2012) and the record of the oral hearing in which Mr. Jim Ryan (NPWS) provides opinion.
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The written submission of the OPW (dated 21 st November, 2011) addresses flood management, which Westmeath County Council are remitted to manage in any event. I am therefore satisfied that this issue is appropriately dealt with.
With specific reference to the issues raised by Erry Mills, I believe that the issue regarding potential impacts arising from the request of the proposal to supply up to 9.6MGD to the Royal Canal in the summertime operational period becomes defunct when we consider that the mathematically supported water level range of 79.471 m OD (max) to 79.146 m OD (min) is justified and within the current range of water levels experienced at the lake. I am recommending that An Bord Pleanàla imposes a hydrological management Condition to the management committee for the Lough Ennell abstraction as follows: Water abstraction is permitted for water level >79.325 m OD Malin , which is to be measured at Clonsingle weir by continuous automatic recording. Water abstraction from Lough Ennell must cease when water levels reach 79.325 m OD Malin . Therefore from a hydrological and ecological perspective I assess that requests and statements regarding the proposed volumes to be abstracted from Lough Ennell to supply the Royal Canal become defunct because abstraction volumes will be dictated by Lough Ennell’s water level being >79.325 m OD Malin .
With specific reference to the issue raised by JA Shaw & Co, Solicitors, on behalf of Cooley Distilleries, which is that they require a maintenance of a certain flow rate to enable the wheel at Kilbeggan to be kept turning at all stages. They refer to communications with Waterways Ireland that “guarantee the minimum flow from Lough Ennell to be measured at Newell’s Bridge to be 500 l/s….”. However, the minimum compensation fish pass flow proposed at the Lough Ennell outlet control at Clonsingle weir is actually 0.29 m3/s (equating to 290 l/s). Newell’s Bridge is a short distance downstream of Clonsingle weir. Therefore, I would not expect that the intermediate catchment area will result in an increase in minimum flow from 290 l/s to 500 l/s. I have presented simple calculations in Appendix A that account for catchment and Monaghanstown Stream contributions and also detail what might be expected further downstream. My evaluation is that I disagree that the proposers can “guarantee the minimum flow from Lough Ennell to be measured at Newell’s Bridge to be 500 l/s”. The 500 l/s that Shaw and Co. ltd. reference in their correspondence is the actual value for Dry Weather Flow (DWF) at Ballynagore hydrometric station (EPA Hydrometric database Stn. No. 25124 DWF = 0.5 m3/s), which is 5 km streamlength, approximately, downstream of Newell’s Bridge. This 500l/s DWF at Ballynagore hydrometric station is the existing actual minimum flow at a location that is 6 km streamlength, approximately, upstream of the Cooley Distilleries wheel at Kilbeggan. I therefore conclude that despite the apparent confusion in reference to the location at which this minimum flow will occur, the proposal should not affect the ability of the wheel at Kilbeggan to be kept turning at all stages because the justification for the proposal for abstraction rests on the maintenance of Lough Ennell water levels and flows within the historical ranges observed. With respect to the minimum flow that can be expected in the River Brosna upgradient of the wheel at Kilbeggan I note that the EPA submission on this case states that “Stn. No. 25124 Ballynagore has been revised down to a lower figure of 0.427 m3/s by the EPA” (page 3, 3 rd February, 2012). The EPA acknowledges that the River Brosna is already heavily regulated due to hydro-electric development at a number of mills in the catchment. -15-
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5. Conclusions
My overall conclusion, following oral hearing, is that the proposers have now justified the presented hydrology, hydrogeology, assimilation capacity and flooding risk assessments and that the methods applied are appropriate. The scheme has been justified in the context of legal obligations to supply water to the Royal Canal, legal requirements forming the basis of the application for the Abstraction Order for Lough Ennell and the required assessments to demonstrate that Lough Ennell can act as the source of water to the Royal Canal.
The proposed hydrological management condition that I recommend that An Bord Pleanàla must assign to the management committee for the Lough Ennell abstraction is as follows:
Water abstraction is permitted for Lough Ennell water level >79.325 m OD Malin , which is to be measured at Clonsingle weir by continuous automatic recording. Water abstraction for the purpose of supply of water to the Royal Canal from Lough Ennell must cease when water levels reach 79.325 m OD Malin .
With respect to the issue of whether this management condition presents a realistic regime for sustained supply of water to the Royal Canal, I suggest that the applicant has proposed that Lough Ennell can supply water within this range and has requested the sanction for an ‘operate and evaluate’ by management committee. I have provided independent calculations to demonstrate viability of this management condition in Appendix A. NPWS have endorsed a ‘operate and evaluate’ approach. The ‘operate and evaluate’ proposal for the applicant’s presented operational water level range of 79.471 m OD (max) to 79.146 m OD (min) is justified in the context of the hydraulic ability of the Lough Ennell system and the controls proposed. However, in reality, An Bord Pleanàla should not set a maximum operational value as it is not required for protection of the integrity of the European Site, neither is it feasible to control the maximum water level. If the management committee evaluates, after a year or two of operation, that the minimum water level condition as specified cannot sustain either the Royal Canal, in time of water shortage or high lock usage (summer), or the fish pass requirements and downstream Brosna River environment, then the land area and elevation freeboard is available at Clonsingle Weir for a new application that can be presented for evaluation in which operational data is evaluated and appropriately assessed. Westmeath County Council have other water supply sources that will relieve reliance on Lough Owel in the future. Therefore, Lough Ennell will not have to be the only source of water to the Royal Canal in the future.
Signed: ______Date: ___27th August 2012__
Dr. Pamela Bartley BEng, MSc, PhD, MIEI
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References
EPA (2012) Observations from the EPA in relation to the Royal canal Water Supply Scheme from lough Ennell, ladestown, Kilpatrick Bridge and Clonsingle, co Westmeath (25. JA0030). EPA, Office of Climate, Licensing & Resource Use, Wexford. Dated 3 rd February 2012.
ESBI (1998) Investigation of Additional Water Supplies for the Royal Canal. Final Report. ESB International Report No PA626-R1-3.
ESBI (2005) Royal Canal Water Supply – Additional Works. ESB International Report No P4D402A – R002- 0002. March 2005.
ESBI (2009) Royal Canal Water Supply – Cost Update and Groundwater Assessment. ESB International Report No P4D402A – R005-0001. Environment Group, ESBI Engineering and Facility Management ltd., November 2009.
King, J.J & Champ, W.S.T. (2000) Baseline Water Quality Investigations on Lough Carra, Western Ireland, with reference to Water Chemistry, Phytoplankton and Aquatic Plants. Biology and Environment, proceedings of the Royal Irish Academy, Vol. 100B, No. 1, 13 -25 92000), Royal Irish Academy.
Heritage Council (2005) Integrating Policies for Ireland’s Inland Waterways. ISSN 1393 – 6808. The Heritage Council of Ireland Series ISBN 1 901137 77 5.
RPS (2011) Lough Ennell. Abstraction Supply to Royal Canal Environmental Impact Statement. EIS 3 no. Vols. September 2011.
Waterways Ireland (2004) Investigation of Additional Water Supplies for the Royal Canal. ‘Summary of Options’. February 2004.
Waterways Ireland (2012) Royal canal water supply scheme from Lough Ennell to Ladestown – REF 25: JA0030. Submission dated 30 th April 2012.
Written Submissions to An Bord Pleanàla (2012) :Department of Arts, Heritage and the Gaeltacht; Office of Public Works; Noel and Bernie Fay; Peter and Maureen Ganly; Derry Kilroy; Peter Sweetman and Associates.
Written Submissions/Objections to Westmeath County Council (2011): Peppard, Kilroy, JA Shaw & Co, Solicitors on behalf of Cooley Distillery, Lough Ennell Trout Preservation Society, Ganley, Ery Mill, Clara, Co. Offaly.
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Appendix A Hydro-G’s Hydrological Calculations
1. Dealing with Newell’s Bridge and guaranteed flow volume … Working on Dry Weather Flow as the worst case scenario (DWF) and Fisheries Interests?….0.29 m3/s guaranteed minimum fish pass flow + let us add to this the expected DWF from the intermediate catchment area between Clonsingle and Newell’s Bridge (186 km 2 minus 138 km2 = 48 km2)…
a. Now all the data I have for all hydrometric stations for which there are DWF data suggests that on average… we can expect no more from DWF than 0.001m3/s for each km2 of catchment (AVERAGE)… so… 48km2 x 0.001m3/s/km2 = 0.048 m3/s and add this to 0.29 = 0.34 m3/s…. this intermediate catchment area between Clonsingle and Newell’s Bridge, which is 48km2 and includes the 35km2 attributed to Monaghanstown stream…. So – I do disagree that 0.5m3/s is guaranteed at Newell’s Bridge…. Even if we were to take the 0.34m3/s and add August’s minimum historical flow average data (table 4.2) for the Monaghanstown stream = 0.05 m3/s – the max value we could get at Newel’s bridge is 0.34 m3/s +0.05 m3/s = 0.39 m3/s which is still short of 0.5m3/s. So, I disagree with 0.5 m3/s guaranteed for Newell’s Bridge assertion of oral hearing evidences…
b. now the actual DWF ratio for many points on the Brosna suggests that we can get 0.0016 m3/s DWF per km2 – but even at that…0.29 + (48 km2 * 0.0016 m3/s of DWF / km2 catchment = 0.0768 m3/s) = 0.366 m3/s DOES NOT EQUAL 0.5 m3/s….at Newell’s Bridge … So, I still disagree….
2. Now, onto the concerns of Fisheries… for these low flow scenarios…. Ballynagore = what we have DWF data for…. Historical… actual = 0.5m3/s…. this has been enough for the FB to date… lets take the intermediate catchment between Clonsingle and Ballynagore ….. difference in area = (219 km2- 138km2 = 81 km2)… they are going to guarantee Fish pass flow of 0.29 m3/s… add to it the DWF component attributed to the 81 km2 catchment…. At 0.001m3/s DWF / km2 = 0.29 + (81*.001) = 0.37 m3/s WORST CASE SCENARIO BASED ON NATIONAL DWF STATISTICS… but based on DWF ratios for the artificially behaving Brosna…. Fish Pass Flow of 0.29 m3/s +(0.0016 m3/s DWF/km2 * 81km2) = 0.42 m3/s DWF at Ballynagore … still short of 0.5 m3/s DWF recorded at Ballynagore BUT I THINK ITS within an acceptable range in terms of daily flow volume and considering that this scenario is a Minimum Minimum….. DWF…. My calculations concur with the revised values suggested by the EPA February 2012 submission. Dr. Moorkens shall address potential impacts in her assessment.
With Respect to the Ability of Lough Ennell to supply water within the proposed operating range of 79.79.471m OD and 79.146m OD and the necessary Condition that abstraction for the purposes of supply to the Royal canal ceases upon water levels reaching the level of 79.325m OD at Clonsingle weir crest level:
a. I deem that it is practical and that my rough calculations support RPS model. I have completed calculations based on the proposed storage volume between their ENVISAGED/Aspirational MAX of 79.471m OD and crest level of 79.325m OD = water height available = 0.146m. The available storage volume associated with the plan area of the lake and 0.146m = 1715500m3) …. And taking into account outflow minimum fish pass of 0.29m3/s (25056 m3/d):
i. Taking low flow historical data provided in Table 4.2 (EIS, 2011, RPS) and acknowledging the EPA’s point about these being spot measurements: August Cumulative inflows to Lough Ennell upstream of Clonsingle weir = 0.395 m3/s… Fish pass takes 0.29 m3/s of this inflow… leaves us with a 0.105 m3/s (9072 m3/d) balance for us to give to the RC Abstraction … And in August WI estimates that they may need 9.6 MGD (43,632 m3/d)….. Therefore, each day we get 9072 m3/d from inflows and we need to rely on 34,560 m3 storage in Lough Ennell to supply RC -18-
Hydro-G Ref 09245_L Ennell_RC An Bord Pleanàla, PW3005 / JA0030: Lough Ennell
Hydro-G (43,632 – 9072 = 34,560 m3)… if 0.146m = 1715500 m3 storage volume…. Then 1715500/34560 = 49 consecutive days of 9.6 MGD supply volume…. EIS, WIs and Mr Kevin O Sullivan’s evidence states that they might need 9.6 MGD only in July and August (62 days)… Cursory data suggests that at times of minimum august influent flows.. they can meet that demand 49 days of 62….so, it is only POTENTAILLY 13 days of the year that may be problematic if the Lough Ennell Abstraction is limited to crest weir level. …. I don’t believe that they would need 9.6 MGD EACH and EVERY day in July and August… so, working on the caveats that their max level is aspirational… because nature could give us more… and that there will be other rainfall events to replenish storage during this high usage time… AND that there is going to be a guaranteed flow each day down the feeder from Lough Owel to the RC…. I think that the figures stack up… the model is justifiable… The calculations I present here are for the worst case scenario of influent flows of 0.395 m3/s cumulative (table 4.2, EIS).
ii. Relative to the max volume of abstraction proposed as 9.6 MGD, the next highest proposed abstraction rate is 6.8 MGD (30,909 m3/d = Sept/Oct: and the influent flows to Lough Ennell are 0.56 m3/s in September (48,384 m3/d) and 1.96 m3/s in October (169344 m3/d) … so, September is the most conservative dataset… we need 0.29 m3/s of 0.56 m3/s in September… that leaves us a balance available from the influents of 0.27 m3/s (23,328 m3/d) to supply the RC requirement of 6.8 m3/d (30,909 m3/d)…. The shortfall of 7581 m3/d… where shall we get this… what if August was very dry and we had been abstracting 9.6 MGD to give the RC… therefore, we are at crest level…. Option (A) – the influents alone shall allow WL to rise enough above crest level to allow us to supply the RC with 23,328 m3/d (which is approximately the 5MGD that WCC are obliged to supply the Canal) .. or Option B … we rest for a few days and wait for the system to replenish….there is going to be some rain…. So how many days of shortfall in supply to the RC or how much rain must fall on Lough Ennell so that water level rises above crest level enough to supply the full estimated 6.8 MGD requirement… that’s where you need the RPS model…. Because there will be weir overspill of replenishing water… and all that accumulates due to influent flows will not stay in Lough Ennell above weir crest level… BUT, we get back to the eternal circular fact of this case… requests based on volumes required by the RC have no basis in the context of the Habitats Directive or the Habitats Regulations 2011… the volumes available to WIs and WCC are dictated by the volumes available in the lake…. In order to ensure that no potential for damage to the integrity of the European site exists… the consultants have proposed that their simulations show that Lough Ennell can support the requirements of the RC when L Ennell’s storage capacity is relied upon AND when only fish pass flows are allowed once WL in Lough Ennell drops below crest level… On a simplified basis…. I have created Table A1 in order to evaluate WCC’s consultant’s assertions….. The result of my work in the creation of Table A1 is to conclude that the proposed protective water level range and cessation of abstraction at weir level provides a justifiable and workable management scenario for protection of the integrity of Lough Ennell as a European site and the practicality of supply of water to the Royal Canal.
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Table A1 Hydro-G’s alternative hydrological calculations May Jun Jul Aug Sep Oct EIS Table 4.2 Cumulative monthly flows (m3/s) into Lough Ennell 0.82 0.454 0.419 0.395 0.56 1.96 EIS Table 4.2 Cumulative monthly flows (m3/day) into Lough Ennell [A] 70848 39226 36202 34128 48384 169344
Fish pass Minimum Flow out (m3/s) 0.29 0.29 0.29 0.29 0.29 0.29 Fish pass Minimum Flow out (m3/day) [B] 25056 25056 25056 25056 25056 25056
Balance available to supply Royal Canal (m3/d) [A -B] Consideration of INFLUENTS only 45,792 14,170 11,146 9,072 23,328 144,288
RC 5 MGD requirement 5 5 5 5 5 5 RC Requirement m3/d 22,272 22,272 22,272 22,272 22,272 22,272 SHORTFALL (m3/d) Required of Storage Volume in event of 5MGD every day none 8,102 11,126 13,200 none none
2011 EIS & Oral Hearing Submissions (RPS) requested RC Requirement MGD 5 5 9.6 9.6 6.8 6.8 2011 EIS & Oral Hearing Submissions (RPS) requested RC Requirement m3/d 22,272 22,272 43,636 43,636 30,909 30,909 SHORTFALL Required of Storage Volume (m3/d) none 8,102 32,490 34,564 7,581 none
? What data can we use to evaluate where the shortfalls shall be obtained…ie. potential volume in storage in the system attributed to carry over of surplus storage on a daily basis? we cannot look at historical water levels because those data are for a Lake in which there was an uncontrolled discharge and therefore, no potential to build up storage. The EPA (written submission, 3rd February 2012) have provided validation of teh proposal regarding storage mm and available yield (page 2, EPA, 2012) - but their calculations relate to 632mm and 332 mm Storage. The operating range proposed at oral hearing was 79.471 m OD (maximum aspirational, because nature shall dictate actual max) to 79.146 m OD simulated minimum BUT abstraction to the Royal canal shall cease at 79.325m OD (EIS 2011, pages 46, 47 and 48, Volume 2, main Report). Therefore the storage available is 79.471 - 79.325 = 146 mm. In any case, the EPA's independent 'Hydrological Evaluation' values for yield avaialble can be factored for 146mm Storage and their data still supports the ability of Lough Ennell to provide the yield for the abstraction (i.e. 146mm/632mm *18.65 MGD = 4.3 MGD and 146mm/332mm *14.63 MGD = 6.4 MGD and the average abstraction will equate to 4 MGD as presented in Mr. Kevin O Sullivan's Oral Hearing Evidence - therefore we are wit
Note the yield available for different storage heights is not linear because of the Lapworth Chart methodology used by the EPA - that is acceptable). However, these verifications rely on average Abstraction data.
However, Oral Evidence Mr. Tom Quigley of RPS (page 3, bottom two paragraphs) …. If the proposed regime was in place…. Extrapolating historical data on water levels suggests that minimum water level would be 79.322 m OD and maximum water level would be 79.471 m OD.. So, I assume RPS's model gives them an expected simulated daily water level thatt has allowed them to determine the available storage when the operating regime is in place.... But in terms of data that i have available to me... in the absence of the detail of the RPS model....let's look at Rainfall purely falling on the actual lake's surface area....
LAKE SURFACE AREA (m2) 11750000
We know that average annual RF = 917 mm/yr… so, in theory we have >1mm RF per day…. Actual Met EIREANN Statistics for mullingar report that in July and August there are ~ 11 days when RF >1mm/d and ~ 4 days when RF > 5 mm /d 1mm/d Rafinfal contributes (m3) over lake surface only 11750
SHORTFALL BASED on 2011 EIS requested Volumes & 1mm /d RF none none 20,740 22,814 none none SHORTFALL BASED on 2011 EIS requested Volumes & 2mm /d RF none none 8,990 11,064 none none
SHORTFALL (m3/d) Required of Storage Volume in event of 5MGD every day and 1 mm/d RF none none none 1,450 none none SHORTFALL (m3/d) Required of Storage Volume in event of 5MGD every day and 2 mm/d RF none none none none none none
These are very simplified calculations because, with the data available to me, specifically spot measurements relating to 1975 AFF data, I cannot set up the same model as RPS in which the carry over volumes built up in storage can be devoted to abstraction in following days…. But my main conclusion is the same... RPS state that L Ennell can support abstraction to RC within the specified range of 79.146 m and 79.471 m (this is acceptable) and they state on many occasions in the EIS that their simulation relies on abstraction ceases at weir crest level.... I can follow their calculations and model to a certain extent and therefore I would suggest to ABP to accept it... but i cannot provide an independent simulation that demonstrates the storage volumes carry over to ensure sustained supply at the high demand of the RC and low hydrological supply in August . I can supply back of envelloppe calculations that show that if we start from the MAX envisaged WL of 79.471 m then we have 0.146m of freeboard above the weir and that gives us 1715500m3 volume of water in storage available to make up those Shortfalls... worst case scenario = Max WL is there in May.. and if we sum each day's shorfall (increasing as we move through to August....)
Summing Jun, July, August Shortfalls… assuming no rainfall at all… and assuming WCC abstract those daily volumes as requested in 2011 EIS & at Oral Hearing…. Cummaltive shorfall Total (m3) Jun - Sept 2,557,291 Available storage volume (m3) 1,715,500 butMISSING I am not HYDROLOGICAL overly concerned… COMPONENT because (m3) I have NO Rainfall included here… and Mullingar 1979–2008 avera841,791ges Met Eireann tells us that in the Jun - Sept period we shall have at least 16 days with > 5mm Rain and if I INCLUDE ONLY THESE > 5 mm RF DAYS and calulate the volume of rain that shall fall on the lake surface only, not counting rainfall contributions from catchments to the streams feeding Lough Ennell...... I have accounted for my missing hydrological component...AND THERE will be other days with even greater RF... Met Eireann Mullingar report (1979 - 2008). m3 volume created by 16 no. raindays with >5 mm RF over 11.75 km2 lake area (Jun - Sept historical data Met Eireann) 940,000
Conclusion Proposed protective water level range and cessation of abstraction at weir level provides a justifiable and workable management scenario for protection of the integrity of Lough Ennell as a European site and the practicality of supply of water to the Royal Canal.
Signed: ______Date: ___27 th August 2012__
Dr. Pamela Bartley BEng, MSc, PhD, MIEI
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