TABLE D.1(i)(a): EMISSIONS TO SURFACE/GROUND WATERS (Primary Discharge Point)
Discharge Point Code: SW1(P)
Source of Emission: Athlone Waste Water Treatment Works
Location: Golden Island, Athlone, Co. Westmeath.
Grid Ref. (12 digit, 6E, 6N): 204152, 240545 Name of receiving waters: River Shannon River Basin District: Shannon Designation of receiving waters: SAC, SPA, NHA
Flow rate in receiving waters: (Regulation requiring the ESB to maintain a minimum flow over weir of) 12 m3.sec-1 Dry Weather Flow 22.4 m3.sec-1 95%ile flow
Emission Details:
(i) Volume emitted
Normal/day 6500 m3 Maximum/day .17,835 m3
Maximum rate/hour 729 m3 Period of emission (avg) min/hr hr/day 365 day/yr
Dry Weather Flow 0.046 m3/sec
Discharge Licence Application Form CD VersionAttach ANNEX – Standard Forms TABLE D.1(i)(b): EMISSIONS TO SURFACE/GROUND WATERS - Characteristics of the emission (Primary Discharge Point)
Discharge Point Code: SW1 (P)
Number Substance As discharged
Max. daily average 1 pH 7.82 2 Temperature 20.7 3 Electrical Conductivity(@25oC) 0.971 Max. daily average (mg/l) kg/day 4 Suspended Solids 32 215 5 Ammonia (as N) 23.6 105 6 Biochemical Oxygen Demand 23 103 7 Chemical Oxygen Demand 72 316 8 Total Nitrogen (as N) 34 217 9 Nitrite (as N) Not available Not available 10 Nitrate (as N) 2.8 13.1 11 Total Phosphorus (as P) 7.8 15 12 Orthophosphate (as P)Note 1 5.7 11
13 Sulphate (SO4) Not available Not available 14 Phenols (sum) Note 2 (ug/l) Not available Not available Note 1: For waste water samples this monitoring should be undertaken on a sample filtered on 0.45μm filter paper. Note 2: USEPA Method 604, AWWA Standard Method 6240, or equivalent. * Conductivity @ 25oC
Discharge Licence Application Form CD VersionAttach ANNEX – Standard Forms TABLE D.1(i)(c): DANGEROUS SUBSTANCE EMISSIONS TO SURFACE/GROUND WATERS
Primary Discharge Point - Characteristics of the emission
Discharge Point Code: SW1(P)
Number Substance As discharged
Max. daily average kg/day kg/year+ (μg/l)Note 1 1 Atrazine <0.01 Not detected Not detected 2 Dichloromethane <1 Not detected Not detected 3 Simazine <0.01 Not detected Not detected 4 Toluene <1 Not detected Not detected 5 Tributyltin (as Sn) Not Available Not Available Not Available 6 Xylenes <1 Not detected Not detected 7 Arsenic 1 0.006 2.19 8 Chromium 1 0.006 2.19 9 Copper 6 0.039 14.25 10 Cyanide 6 0.039 14.25 11 Fluoride <0.09 Not detected Not detected 12 Lead 1 0.006 2.19 13 Nickel 3 0.019 6.93 14 Zinc 57.3 0.372 135.78 15 Boron 252 1.638 597.87 16 Cadmium <0.09 Not detected Not detected 17 Mercury <0.2 Not detected Not detected 18 Selenium 2 0.013 4.745 19 Barium 15 0.097 35.40 Note 1: Only 1 composite sample taken on 21/11/2007 analysed for dangerous substances.
Discharge Licence Application Form CD VersionAttach ANNEX – Standard Forms TABLE D.1(ii)(a): EMISSIONS TO SURFACE/GROUND WATERS (Secondary Discharge Point) (1 table per discharge point)
Discharge Point Code: Not Applicable
Source of Emission:
Location:
Grid Ref. (12 digit, 6E, 6N): Name of receiving waters:
River Basin District:
Designation of receiving waters:
Flow rate in receiving waters: m3.sec-1 Dry Weather Flow m3.sec-1 95%ile flow
Emission Details:
(i) Volume emitted
Normal/day m3 Maximum/day m3
Maximum rate/hour m3 Period of emission min/hr hr/day day/yr (avg)
Dry Weather Flow m3/sec
Discharge Licence Application Form CD VersionAttach ANNEX – Standard Forms TABLE D.1(ii)(b): EMISSIONS TO SURFACE/GROUND WATERS - Characteristics of the emission (1 table per discharge point) (Secondary Discharge Point)
Discharge Point Code: Not Applicable
Number Substance As discharged
Max. daily average 1 pH 2 Temperature 3 Electrical Conductivity (@25oC) Max. daily average (mg/l) kg/day 4 Suspended Solids 5 Ammonia (as N) 6 Biochemical Oxygen Demand 7 Chemical Oxygen Demand 8 Total Nitrogen (as N) 9 Nitrite (as N) 10 Nitrate (as N) 11 Total Phosphorus (as P) Note 1 12 Orthophosphate (as P)
13 Sulphate (SO4) 14 Phenols (sum) Note 2 (ug/l) Note 1: For waste water samples this monitoring should be undertaken on a sample filtered on 0.45μm filter paper. Note 2: USEPA Method 604, AWWA Standard Method 6240, or equivalent.
Discharge Licence Application Form CD VersionAttach ANNEX – Standard Forms TABLE D.1(ii)(c): DANGEROUS SUBSTANCE EMISSIONS TO SURFACE/GROUND WATERS
Secondary Discharge Point - Characteristics of the emission (1 table per discharge point)
Discharge Point Code: Not Applicable
Number Substance As discharged
Max. daily kg/day kg/year average (μg/l) 1 Atrazine 2 Dichloromethane 3 Simazine 4 Toluene 5 Tributyltin 6 Xylenes 7 Arsenic 8 Chromium 9 Copper 10 Cyanide 11 Fluoride 12 Lead 13 Nickel 14 Zinc 15 Boron 16 Cadmium 17 Mercury 18 Selenium 19 Barium
Discharge Licence Application Form CD VersionAttach ANNEX – Standard Forms TABLE D.1(iii)(a): EMISSIONS TO SURFACE/GROUND WATERS (Storm Water Overflow) (1 table per discharge point)
Discharge Point Code: S.O.1
Source of Emission: Burgess Park SWO
Location: Golden Island Pumping Station discharge point
Grid Ref. (12 digit, 6E, 6N): 204156E, 241041N Name of receiving waters: River Shannon River Basin District: Shannon River Basin District Designation of receiving waters: SAC, SPA, NHA
Flow rate in receiving waters: (Automatic Data Logger 26027) 6 m3.sec-1 Dry Weather Flow 22.4 m3.sec-1 95%ile flow
Emission Details:
(i) Volume emitted
Normal/day 0m3 Maximum/day 1770m3
Maximum rate/hour 101m3 Period of emission min/hr 1 hr/day CHECK day/yr (avg)
Discharge Licence Application Form CD VersionAttach ANNEX – Standard Forms
TABLE D.1(iii)(a): EMISSIONS TO SURFACE/GROUND WATERS (Storm Water Overflow) (1 table per discharge point)
Discharge Point Code: S.O.2
Source of Emission: Love Lane SWO
Location: Love Lane
Grid Ref. (12 digit, 6E, 6N): 204828E, 241689N Name of receiving waters: Al River River Basin District: Shannon River Basin District Designation of receiving waters: Not Designated
Flow rate in receiving waters: Not Available m3.sec-1 Dry Weather Flow Not Available m3.sec-1 95%ile flow
Emission Details:
(i) Volume emitted
Normal/day 0m3 Maximum/day 0m3
Maximum rate/hour 0m3 Period of emission min/hr hr/day 0 day/yr (avg)
Discharge Licence Application Form CD VersionAttach ANNEX – Standard Forms
TABLE D.1(iii)(a): EMISSIONS TO SURFACE/GROUND WATERS (Storm Water Overflow) (1 table per discharge point)
Discharge Point Code: S.O.3
Source of Emission: Abbey Road Pumping Station SWO
Location: Abbey Road Pumping Station
Grid Ref. (12 digit, 6E, 6N): 203943E, 241685N Name of receiving waters: River Shannon River Basin District: Shannon River Basin District Designation of receiving waters: SAC, SPA, NHA
Flow rate in receiving waters: (Automatic Data Logger 26027) 6 m3.sec-1 Dry Weather Flow 22.4 m3.sec-1 95%ile flow
Emission Details:
(i) Volume emitted
Normal/day 0m3 Maximum/day 2567m3
Maximum rate/hour 325m3 Period of emission min/hr 1 hr/day 115 day/yr (avg)
Discharge Licence Application Form CD VersionAttach ANNEX – Standard Forms
TABLE D.1(iii)(a): EMISSIONS TO SURFACE/GROUND WATERS (Storm Water Overflow) (1 table per discharge point)
Discharge Point Code: S.O.4
Source of Emission: Coosan East Pumping Station
Location: Coosan
Grid Ref. (12 digit, 6E, 6N): 204328E, 242628N Name of receiving waters: River Shannon River Basin District: Shannon River Basin District Designation of receiving waters: SAC, SPA, NHA
Flow rate in receiving waters: (Automatic Data Logger 26027) 6 m3.sec-1 Dry Weather Flow 22.4 m3.sec-1 95%ile flow
Emission Details:
(i) Volume emitted
Normal/day 0m3 Maximum/day 31m3
Maximum rate/hour 17m3 Period of emission min/hr 1 hr/day 3 day/yr (avg)
Discharge Licence Application Form CD VersionAttach ANNEX – Standard Forms
TABLE D.1(iii)(a): EMISSIONS TO SURFACE/GROUND WATERS (Storm Water Overflow) (1 table per discharge point)
Discharge Point Code: S.O.5
Source of Emission: Coosan West Pumping Station
Location: Coosan
Grid Ref. (12 digit, 6E, 6N): 203685E, 242655N Name of receiving waters: River Shannon via Athlone Bypass Drain River Basin District: Shannon River Basin District Designation of receiving waters: SAC, SPA, NHA
Flow rate in receiving waters: (Automatic Data Logger 26027) 6 m3.sec-1 Dry Weather Flow 22.4 m3.sec-1 95%ile flow
Emission Details:
(i) Volume emitted
Normal/day 0m3 Maximum/day 3m3
Maximum rate/hour 10m3 Period of emission min/hr 0.3 hr/day 1 day/yr (avg)
Discharge Licence Application Form CD VersionAttach ANNEX – Standard Forms
TABLE D.1(iii)(a): EMISSIONS TO SURFACE/GROUND WATERS (Storm Water Overflow) (1 table per discharge point)
Discharge Point Code: S.O.6
Source of Emission: Roscommon Road Pumping Station
Location: Roscommon Road
Grid Ref. (12 digit, 6E, 6N): 202670E, 241883N Name of receiving waters: Surface Water Sewer outfalls to land drain draining to Athlone Canal River Basin District: Shannon River Basin District Designation of receiving waters: Partially designated SAC, SPA, NHA
Flow rate in receiving waters: Not Available m3.sec-1 Dry Weather Flow Not Available m3.sec-1 95%ile flow
Emission Details:
(i) Volume emitted
Normal/day 0m3 Maximum/day 6m3
Maximum rate/hour 11m3 Period of emission min/hr 0.3 hr/day 7 day/yr (avg)
Discharge Licence Application Form CD VersionAttach ANNEX – Standard Forms
TABLE D.1(iii)(a): EMISSIONS TO SURFACE/GROUND WATERS (Storm Water Overflow) (1 table per discharge point)
Discharge Point Code: S.O.7
Source of Emission: West Bank Pumping Station
Location: West Bank
Grid Ref. (12 digit, 6E, 6N): 203984E, 241226N Name of receiving waters: River Shannon via surface water pipe River Basin District: Shannon River Basin District Designation of receiving waters: SAC, SPA, NHA
Flow rate in receiving waters: (Automatic Data Logger 26027) 6 m3.sec-1 Dry Weather Flow 22.4 m3.sec-1 95%ile flow
Emission Details:
(i) Volume emitted
Normal/day 0m3 Maximum/day 3168m3
Maximum rate/hour 577m3 Period of emission min/hr 2 hr/day 116 day/yr (avg)
Discharge Licence Application Form CD VersionAttach ANNEX – Standard Forms
TABLE D.1(iii)(a): EMISSIONS TO SURFACE/GROUND WATERS (Storm Water Overflow) (1 table per discharge point)
Discharge Point Code: S.O.8
Source of Emission: Canal Lower, Clonoun Road SWO
Location: Clonoun Road
Grid Ref. (12 digit, 6E, 6N): 203629E, 240854N Name of receiving waters: Athlone Canal River Basin District: Shannon River Basin District Designation of receiving waters: Partially designated SPA, NHA, SAC
Flow rate in receiving waters: Not Available m3.sec-1 Dry Weather Flow Not Available m3.sec-1 95%ile flow
Emission Details:
(i) Volume emitted
Normal/day 0m3 Maximum/day 0m3
Maximum rate/hour 0m3 Period of emission min/hr hr/day 0 day/yr (avg)
Discharge Licence Application Form CD VersionAttach ANNEX – Standard Forms
TABLE D.1(iii)(a): EMISSIONS TO SURFACE/GROUND WATERS (Storm Water Overflow) (1 table per discharge point)
Discharge Point Code: S.O.9
Source of Emission: Canal Mid, Galway Road SWO
Location: Galway Road
Grid Ref. (12 digit, 6E, 6N): 203198E, 241781N Name of receiving waters: Athlone Canal River Basin District: Shannon River Basin District Designation of receiving waters: Partially designated SPA, NHA, SAC
Flow rate in receiving waters: Not Available (m3.sec-1 Dry Weather Flow Not Available m3.sec-1 95%ile flow
Emission Details:
(i) Volume emitted
Normal/day 0m3 Maximum/day 143m3
Maximum rate/hour 135m3 Period of emission min/hr 1.2 hr/day 6 day/yr (avg)
Discharge Licence Application Form CD VersionAttach ANNEX – Standard Forms
TABLE D.1(iii)(a): EMISSIONS TO SURFACE/GROUND WATERS (Storm Water Overflow) (1 table per discharge point)
Discharge Point Code: S.O.10
Source of Emission: Canal Upper, Iona Park SWO
Location: Canal Upper, Iona Park
Grid Ref. (12 digit, 6E, 6N): 203111E, 241984N Name of receiving waters: Athlone Canal River Basin District: Shannon River Basin District Designation of receiving waters: Partially designated SPA, NHA, SAC
Flow rate in receiving waters: Not Available m3.sec-1 Dry Weather Flow Not Available m3.sec-1 95%ile flow
Emission Details:
(i) Volume emitted
Normal/day 0m3 Maximum/day 0m3
Maximum rate/hour 0m3 Period of emission min/hr hr/day 0 day/yr (avg)
Discharge Licence Application Form CD VersionAttach ANNEX – Standard Forms
TABLE D.1(iii)(a): EMISSIONS TO SURFACE/GROUND WATERS (Storm Water Overflow) (1 table per discharge point)
Discharge Point Code: S.O.11
Source of Emission: Magazine Road SWO
Location: Magazine Road
Grid Ref. (12 digit, 6E, 6N): 203390E, 241990N Name of receiving waters: River Shannon River Basin District: Shannon River Basin District Designation of receiving waters: SPA, NHA, SAC
Flow rate in receiving waters: (Automatic Data Logger 26027) 6 m3.sec-1 Dry Weather Flow 22.4 m3.sec-1 95%ile flow
Emission Details:
(i) Volume emitted
Normal/day 0m3 Maximum/day 9m3
Maximum rate/hour 32m3 Period of emission min/hr 0.3 hr/day 1 day/yr (avg)
Discharge Licence Application Form CD VersionAttach ANNEX – Standard Forms
TABLE D.1(iii)(a): EMISSIONS TO SURFACE/GROUND WATERS (Storm Water Overflow) (1 table per discharge point)
Discharge Point Code: S.O.12
Source of Emission: Deer Park Road SWO
Location: Deer Park Road
Grid Ref. (12 digit, 6E, 6N): 203903E, 241098N Name of receiving waters: Shannon River River Basin District: Shannon River Basin District Designation of receiving waters: SPA, NHA, SAC
Flow rate in receiving waters: (Automatic Data Logger 26027) 6 m3.sec-1 Dry Weather Flow 22.4 m3.sec-1 95%ile flow
Emission Details:
(i) Volume emitted
Normal/day 0m3 Maximum/day 0m3
Maximum rate/hour 0m3 Period of emission min/hr hr/day 0 day/yr (avg)
Discharge Licence Application Form CD VersionAttach ANNEX – Standard Forms
TABLE D.1(iii)(a): EMISSIONS TO SURFACE/GROUND WATERS (Storm Water Overflow) (1 table per discharge point)
Discharge Point Code: S.O.13
Source of Emission: Northgate Street SWO
Location: Northgate Street
Grid Ref. (12 digit, 6E, 6N): 203968E, 241688N Name of receiving waters: Shannon River River Basin District: Shannon River Basin District Designation of receiving waters: SPA, NHA, SAC
Flow rate in receiving waters: (Automatic Data Logger 26027) 6 m3.sec-1 Dry Weather Flow 22.4 m3.sec-1 95%ile flow
Emission Details:
(i) Volume emitted
Normal/day 0m3 Maximum/day 0m3
Maximum rate/hour 0m3 Period of emission min/hr hr/day 0 day/yr (avg)
Discharge Licence Application Form CD VersionAttach ANNEX – Standard Forms
TABLE D.1(iii)(a): EMISSIONS TO SURFACE/GROUND WATERS (Storm Water Overflow) (1 table per discharge point)
Discharge Point Code: S.O.14
Source of Emission: Coosan Road SWO
Location: Coosan Road
Grid Ref. (12 digit, 6E, 6N): 203716, 242200 Name of receiving waters: River Shannon via surface water pipe River Basin District: Shannon River Basin District Designation of receiving waters: SPA, NHA, SAC
Flow rate in receiving waters: (Automatic Data Logger 26027) 6 m3.sec-1 Dry Weather Flow 22.4 m3.sec-1 95%ile flow
Emission Details:
(i) Volume emitted
Normal/day 0m3 Maximum/day 56m3
Maximum rate/hour 55m3 Period of emission min/hr 0.7 hr/day 9 day/yr (avg)
Discharge Licence Application Form CD VersionAttach ANNEX – Standard Forms
TABLE D.1(iii)(a): EMISSIONS TO SURFACE/GROUND WATERS (Storm Water Overflow) (1 table per discharge point)
Discharge Point Code: S.O.15
Source of Emission: Siphon SWO
Location: West Side
Grid Ref. (12 digit, 6E, 6N): 204040E, 240941N Name of receiving waters: Shannon River River Basin District: Shannon River Basin District Designation of receiving waters: SAC, SPA, NHA
Flow rate in receiving waters: (Automatic Data Logger 26027) 6 m3.sec-1 Dry Weather Flow 22.4 m3.sec-1 95%ile flow
Emission Details:
(i) Volume emitted
Normal/day 0m3 Maximum/day 6073m3
Maximum rate/hour 516m3 Period of emission min/hr 2 hr/day 91 day/yr (avg)
Discharge Licence Application Form CD VersionAttach ANNEX – Standard Forms
TABLE D.1(iii)(a): EMISSIONS TO SURFACE/GROUND WATERS (Storm Water Overflow) (1 table per discharge point)
Discharge Point Code: S.O.16
Source of Emission: Lower Road SWO
Location: Lower Road
Grid Ref. (12 digit, 6E, 6N): 204627E, 241342N Name of receiving waters: Al River River Basin District: Shannon River Basin District Designation of receiving waters: Not Designated
Flow rate in receiving waters: Not Available m3.sec-1 Dry Weather Flow Not Available m3.sec-1 95%ile flow
Emission Details:
(i) Volume emitted
Normal/day 0m3 Maximum/day 0m3
Maximum rate/hour 0m3 Period of emission min/hr hr/day 0 day/yr (avg)
Discharge Licence Application Form CD VersionAttach ANNEX – Standard Forms
TABLE D.1(iii)(a): EMISSIONS TO SURFACE/GROUND WATERS (Storm Water Overflow) (1 table per discharge point)
Discharge Point Code: S.O.17
Source of Emission: Lower Road / Castlemaine Street SWO
Location: Lower Road / Castlemaine Street
Grid Ref. (12 digit, 6E, 6N): 204719E, 241347N Name of receiving waters: Al River River Basin District: Shannon River Basin District Designation of receiving waters: Not Designated
Flow rate in receiving waters: Not Available m3.sec-1 Dry Weather Flow Not Available m3.sec-1 95%ile flow
Emission Details:
(i) Volume emitted
Normal/day 0m3 Maximum/day 0m3
Maximum rate/hour 0m3 Period of emission min/hr hr/day 0 day/yr (avg)
Discharge Licence Application Form CD VersionAttach ANNEX – Standard Forms
TABLE D.1(iii)(a): EMISSIONS TO SURFACE/GROUND WATERS (Storm Water Overflow) (1 table per discharge point)
Discharge Point Code: S.O.18
Source of Emission: Castlemaine Street SWO
Location: Castlemaine Street
Grid Ref. (12 digit, 6E, 6N): 204824E, 241254N Name of receiving waters: Al River River Basin District: Shannon River Basin District Designation of receiving waters: Not Designated
Flow rate in receiving waters: Not Available m3.sec-1 Dry Weather Flow Not Available m3.sec-1 95%ile flow
Emission Details:
(i) Volume emitted
Normal/day 0m3 Maximum/day 0m3
Maximum rate/hour 0m3 Period of emission min/hr hr/day 0 day/yr (avg)
Discharge Licence Application Form CD VersionAttach ANNEX – Standard Forms Modelling of Discharges from the Agglomeration Attachment D.1
The Section below outlining the modelling of discharges from the agglomerations has been extracted from the Athlone Drainage Study Review Preliminary Report 2004
1.1 Introduction
The initial and most important stage of any drainage area study is the collection and collation of all available data and the surveying of the existing infrastructure where deficiencies exist in the available data. It was decided at the commencement of the Study to undertake further surveys for model construction, model verification and the possible identification of required sewer remediation, in order to augment the information already available. The additional surveys undertaken were as follows;
• Topographical Survey; • Digital Mapping; • Manhole Survey; • Pumping Station Survey; • CCTV Survey and Sewer Defects Survey; • Flow and Rainfall Survey; • Impermeable Area Survey;
1.2 Collation of Existing Data
In liaison with the relevant departments of Westmeath County Council, all available relevant data for the study was assembled, which included:
• Previous reports on the study area; • Westmeath County Council Drainage Records; • Pumping Station Records & Design Data; • Topographical Information; • Digital Cadastral Mapping; • 1994 County Development Plan & 2000 Draft County Development Plan; • Planning Records; • Existing Flow & Rainfall Survey; and, • Other data relevant to the study.
The necessity for and extent of any further survey work was dependent upon the quality of the system data already available. Prior to the preparation of any survey contract documents a review of the data deficiencies and recommendations for further survey work was undertaken. It was subsequently decided to carry out the survey work specified below.
1.3 Topographical Survey
Limited topographical information of the study area was available. This included mapping from the Ordnance Survey Discovery Series complemented by spot levels from Ordnance Survey Mapping.
A survey of the area using airborne laser scanning was carried out in order to provide ground contours. Use was made of the survey data for plotting sewer sections and determining catchment boundaries.
Modelling of Discharges from the Agglomeration Attachment D.1
1.4 Digital Mapping
The Ordnance survey mapping of the catchment, which was made available in digital format, was supplemented by the aerial survey for the production of a digital ground model. The aerial survey was carried out by Aero Maps Ltd. 1.5 Manhole Database Survey
At the commencement of the Study, it became evident that Westmeath County Council records of the drainage configuration of the study area were limited. It was therefore proposed that a complete manhole survey of the study area be undertaken.
The survey was carried out by USA Ltd. following a short list tendering process. The survey commenced in November 2001. The data was presented in SUS25 format, and is accessible using the SUS25 or Mapdrain software. Record maps of the sewer runs were also produced.
Each manhole was assigned a unique reference, in line with the STC25 manhole referencing system. Manhole data, accessible from the database, includes the following:
• Location; • Cover Level and Type; • Shaft and Chamber Dimensions; • System Type (foul/combined/storm); • Incoming/outgoing pipe invert levels, shape, size etc.; and, • Upstream/downstream connectivity.
The existing trunk collection system contains approximately 3,100 manholes
The specification for the survey was in line with best practice and following the UK Water Industry ‘Model Contract Document for Manhole Location Surveys and the Production of Record Maps’. The manhole survey database was readily transferable into the hydraulic modelling software InfoWorks CS for model construction.
1.6 Pumping Station Survey
We are aware from our prior knowledge of the sewer network that the pumping stations serving the UDC area and Coosan East and Coosan West are under considerable strain at present. In light of proposed developments in the catchment and hence future demands on the pumping station a more complete survey of the pumping stations was necessary. A Mechanical & Electrical Survey of 8 of the town’s main pumping stations was carried out which comprised the following elements:
• Inspection of control panel – including physical condition and condition of wiring; • Drop Test – to ascertain the actual performance curve of the pumps, in all combinations; • Comparison of actual pump performance and the design performance curves for the pumps; • Capability for integration into telemetry system; and, • Condition of station with regard to siltation and build-up of grease.
The structural condition of the station was also examined, in order to ascertain the feasibility of station expansion, if necessary.
Modelling of Discharges from the Agglomeration Attachment D.1
1.7 CCTV Survey and Sewer Cleaning
Due to the perceived structural deficiencies in the existing network and uncertainty over the connectivity of the network, it was decided at the commencement of the Study that a remote camera inspection of the internal condition of the existing sewerage system was required. In order to execute the survey in full, it was also necessary to clean a large amount of the sewerage system.
The CCTV Survey and Cleaning Contract was carried out by USA Ltd. following a short list tendering process. The survey commenced in March 2002. The survey was carried out in accordance with the UK Water Industry ‘Model Contract Document for Sewer Condition Inspection’. Pan & Tilt cameras were used with the capability of surveying even small diameter pipes.
The CCTV survey information was provided in Examiner format, which is readily usable for sewer evaluation and interpretation. The survey videos were also provided in CD-ROM format.
Each sewer length was described in detail according to:
• Shape • Material • Use (foul/combined/storm) • Lengths between upstream and downstream manholes • Sewer defect (if any)
Remarks were recorded along the length of the survey according to silt levels, water level, obstructions, general condition and structural condition of the sewer. Surface water infiltration into the sewer through cracks or displaced joints was also noted.
The structural performance of the system, based upon the CCTV survey, was then assessed using the WRC ‘Sewer Rehabilitation Manual, Third Edition’ internal condition grading system which determines whether the sewers in question require renewal or renovation. The manual provides a rigorous methodology by which the structural deficiencies in the sewerage network are identified from examination of the CCTV records. Sewer defects are graded 1 to 5, with Grade 5 being the most critical (collapse, blockage, etc) and in need of immediate attention. In general sewers with defects graded 4 or 5 should be dealt with in the short term (1 to 2 years).
Included in this and in the modelling study in general was an assessment of the infiltration of surface water into the wastewater network through faulty pipework or illegal connections etc. Any rehabilitation programme will include for the elimination of infiltration, where possible.
Data from the CCTV survey was also integrated into the InfoWorks model of the sewer systems.
1.8 Flow and Rainfall Survey
It was decided at the commencement of the Study to carry out a Flow and Rainfall Survey over the full Athlone Catchment. The survey was to be undertaken generally in accordance with ‘A Guide to Short Term Flow Surveys of Sewer Systems’ published by the WRC. Such surveys are short-term, with an initial survey period of five weeks that may be extended on an event dependent basis beyond this period. The aim of the survey was to monitor depth, flow and velocity data at a number of critical points in the sewerage system over two dry weather flow Modelling of Discharges from the Agglomeration Attachment D.1
days (weekday and weekend) and three significant rainfall events. The rainfall events are required to be of minimum set intensity and duration, with a minimum required response to rainfall at the flow monitoring sites. The required number of flow monitors was based upon a number of criteria, but were typically located at the following locations;
• overflows • cross-connections between foul and stormwater systems • downstream of critical sub-catchments • downstream of pumping stations, weirs etc • near major junctions with trunk sewers etc
It was also proposed to install or utilise existing monitoring equipment at the pumping stations during the survey, to record liquid levels in sumps and pump runtimes.
Rain gauges were distributed throughout the study area in order to capture the spatial variation of rainfall.
The flow and rainfall survey was carried out by Indepth Surveys between the 16th April 2002 and the 25th June 2002. It was necessary to extend the survey period beyond 5 weeks in order to acquire the required 3 significant rainfall events.
The survey used flow monitors in sewers, depth and pump monitors at pumping stations and raingauges in exposed locations. Flow monitors were located throughout the catchment at critical points in the collection system. The raingauges were spatially distributed throughout the catchment. The locations of all monitoring equipment (consisting 6 rain gauges, 60 flow monitors and 11 pump monitors) are shown on Drawings No 743/01/1013 and 1014 attached.
The survey provided data on the actual performance of the sewer system and these were used for verification of the constructed hydraulic models of the catchment. The verified model was used to determine dry weather flow conditions, assess infiltration to the system and assess the stormwater contribution to the system (see Section 3).
1.8.1 Rainfall Survey
Rainfall was monitored using the Casella Tipping Bucket raingauges, connected to a data logger. Each bucket tip was equal to 0.2mm depth of rainfall. Data were recorded at two- minute intervals and retrieved on a weekly basis.
The raingauge sites were chosen in accordance with WRc guidelines. The raingauges were positioned having considered the following guidelines:
• the site must not be sheltered from the true rainfall pattern by trees or buildings • the site must not be overexposed to high winds • the site must be secure from vandalism
The locations of the rainfall gauges are shown in Table 1.1.
Table 1.1 Location of Raingauges
Site No. Location Modelling of Discharges from the Agglomeration Attachment D.1
Site No. Location 1 Statoil Petrol Station, Roscommon Road 2 SDS/An Post, Coosan Road 3 Department of Education, Ballymahon Road 4 Golden Island PS 5 Our Lady's Bower School, Lower Road 6 Athlone Institute of Technology, Dublin Road
In order to satisfactorily verify the Hydraulic Model, 3 significant rainfall and 2 dry weather days were selected for further analysis. These Events are summarised in Table 1.2 below.
Table 1.2 Selected DWF & Rainfall Events
Event Ref Start Finish Duration Depth Max (mins) (mm) Intensity Date Time Date Time (mm/hr) Event 1 03/05/2002 00:00 04/05/2002 00:00 1440 Dry Day 1 Event 2 04/05/2002 00:00 05/05/2002 00:00 1440 Dry Day 2 Event 5 28/05/2002 13:00 29/05/2002 00:00 540 8.1 132 Event 6/7 14/06/2002 16:00 15/06/2002 03:00 660 8.8 54 Event 8 17/05/2002 09:00 18/05/2002 00:00 900 20.5 18 Event 10 27/04/2002 06:00 29/04/2002 12:00 3240 18 30
Rainfall Validation Criteria:
Rainfall data was retrieved and presented to P.H. McCarthy & Partners in weekly reports to allow for the assessment of the rainfall suitability for model verification. In determining the suitability of rainfall events for use in model verification WRc guidelines state that:
• Total depth should be greater than 5mm • Rainfall Intensity should be greater than 6mm/hour for more than 4 minutes • The period between the events should be sufficient for flow to return to dry weather conditions
The WRc also imposes the following limits on the variation between rainfall at adjacent gauge sites:
• Total depth of rainfall should not vary by more than 20% • There should be no more than a 15 minute shift peak time of each peak • There should be no more than 10% variation in the time interval between successive peaks and there should be no more than a 30% variation in mean intensity when measured over 6 minutes at the peaks
Modelling of Discharges from the Agglomeration Attachment D.1
1.8.2 Flow Survey
The flow monitors used were Sigma 911 Survey loggers, which measure depth with a pressure transducer and velocity using an ultrasonic transceiver. At pumping stations depth- only and current clamp monitors were installed. Data were recorded at two-minute intervals and retrieved from the monitors on a weekly basis for the duration of the survey.
The range of accurate measurement with such monitors is as follows:
• Depth: 100 mm to 500 mm • Velocity: 0.2 m/s to 2.0 m/s
Selection of Flow Monitor Sites
Sixty flow monitors were used in the Survey. Monitor sites were selected with reference to the WRc guidelines and in consultation with Westmeath County Council. In accordance with the WRc guidelines, sites with backdrops, bends or other obstructions were avoided. The monitor specifications were also considered, ensuring that adequate depths and velocities could be expected at all sites. Where possible, monitors were placed in the incoming sewer to the manhole where hydraulic conditions are more suitable for flow measurement than in outgoing sewers. When early interim reports were analysed, a number of sites were found to be providing inaccurate data due to inadequate flow conditions (depth of flow less than 100mm) and instruction was given to relocate these monitors to more suitable sites. In total, flow monitoring was carried out at sixty-six sites throughout the catchment.
The ‘Code of Practice for the Hydraulic Modelling of Sewer Systems’ published by the Wastewater Planning Users Group (WAPUG) identifies flow survey data requirements for hydraulic and model verification. In general, the operation of the flow monitors and raingauges was satisfactory. The response of the system at flow monitoring locations was generally good, however some of the smaller diameter sewers not attaining minimum flow requirements for verification during dry weather flows.
The location of all monitors used in the flow survey is shown in Table 1.3 below.
Table 1.3 Location of Flow Monitors
Monitor Pipe Diameter Location Site No. (mm) 1 † Galway Road 150 2 † Galway Road 150 3 † Galway Road 150 4 † Galway Road 150 5 † New housing estate, Galway Road 450 6 Iona Park 450 7 Iona Park 450 8 Galway Road 450 9 Galway Road 225 10 Galway Road 450 11 Battery Heights 225 Modelling of Discharges from the Agglomeration Attachment D.1
Monitor Pipe Diameter Location Site No. (mm) 12 Battery Heights 375 13 Battery Road 400 14 Battery Road 600 15 Meadows 450 16 Meadows 450 17 Meadows 375 18 Golden Island 450 19 Galway Road, adjacent Church 1050x1030 20 The Quay 1200x1000 21 The Quay 1200x1000 22 Golden Island, adjacent Shannon 525 23 Golden Island, adjacent Shannon 525 24 Griffith Street 450 25 Northgate Street 300 26 † Abbey Road/Northgate Street 300 27 Abbey Road 525 28 Abbey Road 300 29 Coosan Road 300 30 Coosan Road 300 31 Coosan West Pedestrian Underpass 300 32 Auburn Drive 525 33 Auburn Drive 450 34 Coosan Point Road 1050 35 Coosan Point Road 225 36 Relief Road (Ballymahon Road exit) 375 37 Golden Island 3400x1600 38 Golden Island 600 39 Golden Island 750 40 Lower Road/Castlemaine Street 350x350 41 Lower Road/Castlemaine Street 225 42 Lower Road/Castlemaine Street 300x300 43 Lower Road/Castlemaine Street 450 44 Pairc Chiarán 1500 45 Marist College 900 46 Marist College 300 47 Love Lane (end of) 1500 48 Love Lane (end of) 525 49 Retreat 300 50 Lissywollen 300 51 Lissywollen 300 Modelling of Discharges from the Agglomeration Attachment D.1
Monitor Pipe Diameter Location Site No. (mm) 52 Brooklawn 525 53 Brooklawn 300 54 Brooklawn 300 55 Dublin Road, Garrycastle Bridge 375 56 Dublin Road, Garrycastle Bridge 300 57 Dublin Road, Al River 600 58 Galway Road 450 59 Deer Park Road 375 60 Deer Park Road 375 72 ΅ Northgate Street 300 73 ΅ Galway Road 225 74 ΅ Galway Road 225 75 ΅ Galway Road 225 76 ΅ New housing estate, Galway Road 225 77 ΅ Roscommon Road 450 † Monitor relocated ΅ New site for relocated monitor
1.8.3 Pumping Stations
Depth monitors were installed in the wet wells of eleven pumping stations throughout the catchment. These are shown in Table 1.4.
Table 1.4 Location of Pump Monitors
Site No. Pumping Station
61 Roscommon Road PS 62 Deer Park PS 63 Priory Park PS, Coosan Road 64 Golden Island PS 65 Abbey Road PS 66 Abbey Road Storm Overflow PS 67 West Bank PS, The Quay 68 Coosan West PS, Coosan Road 69 Coosan East PS, Coosan Point Road 70 Mayfield Grove PS, Ballymahon Road 71 Woodville Grange PS, Cornamaddy
Modelling of Discharges from the Agglomeration Attachment D.1
1.9 Impermeable Area Survey
The study area is drained by separate and combined sewers and an investigation is required to determine the connectivity of the sub-catchments areas to each system. For the purposes of modelling the systems and any subsequent separation of the two systems there needs to be an understanding of:
• drained impermeable surfaces – identified as roofs and roads separately • drained permeable surfaces, including land drains
At the commencement of the Study, it was decided that there would be sufficient information available from existing records, the manhole survey, the flow & rainfall survey and the CCTV survey in order to carry out a desktop assessment of the impermeable areas in the catchment. A walkover survey of the town was also carried out which examined the drainage patterns of developments of differing ages. In general, older estates will be more combined in nature than newer developments. The older town centre areas are usually fully combined.
Data from this assessment can be overlaid on the sewerage network, contour information and sub-catchment plans in the InfoWorks environment, to readily assess the dynamics of each sub-catchment and the entire study area.
Details of Modelling of Discharges from the Agglomeration Attachment D1
2 OVERALL MODELLING METHODOLOGY
2.1 Introduction
Upon receipt of all of the survey information described in Section 1, a detailed structural and hydraulic model of the sewerage system was constructed and analysed. This section of the Report describes the software used and outlines the methodology used to build, verify and analyse the Athlone Hydraulic Model.
2.2 Model Construction
2.2.1 Software
P.H. McCarthy & Partners utilise two Wallingford Software products for the hydraulic modelling of collection systems – HydroWorks PM and InfoWorks CS. The products are mutually compatible, with InfoWorks CS including a GIS (Geographical Information System) capability that can be used to superimpose the models on digital mapping. The software is compatible with the GIS software MapInfo. This proves a useful tool for model construction, network analysis and the presentation of results. InfoWorks CS v5.0 was used in this Study for model construction, verification and system analysis.
2.2.2 Sewer Data
The models are constructed following the ‘Code of Practice for the Hydraulic Modelling of Sewer Systems’, as published by the Wastewater Planning Users Group (WAPUG). Data used to construct the structure of the model included the Westmeath County Council drainage records and the SUS Manhole Survey described in Section 1. The Council records and manhole survey were subject to a validation check on site and any errors reported.
The manhole database is delivered in SUS25 format from the Survey Contractor and is converted into InfoWorks format. Any gaps or anomalies in the data is reported and re-surveyed if necessary. Where manholes were impossible to locate or open, their data can be interpolated from neighbouring manholes using the InfoWorks inferring tool.
Prior to performing any hydraulic runs, the model information must be validated to highlight any potential errors in the data such as missing information, decreasing diameters and negative gradients.
2.2.3 Other Survey Data
As well as providing an assessment of the existing structural condition of the pipework, the CCTV survey data provides information such as sediment depths, hydraulic roughness and infiltration and also provides a check of the physical sewer data. It is possible to import the relevant information directly from the Examiner software or any spreadsheet format.
Athlone Waste Water Discharge Licence Application Details of Modelling of Discharges from the Agglomeration Attachment D1
Data from the pumping station survey is also input into the model at this stage.
Although the data from the Flow Survey is primarily used in the model verification stage the information provided can also give a good indication of the degree of surface water infiltration (direct or otherwise) into the combined sewer upstream of the monitor. Observed flows downstream of pumping stations will also give an indication of the pumping rate and frequency of pumping, where this information does not already exist.
2.2.4 Sub-Catchments
The impermeable area assessment, in conjunction with contour information, site visits and an examination of records will be used to delineate sub-catchment boundaries. A drainage sub-catchment contains information on the following: • Foul loading – calculated from the number of houses, and other properties in the sub-catchmment • Surface water loading – determined by the extent of impermeable and permeable areas in the sub-catchment. The impermeable area / permeable area contribution will be ascertained from digital cadastre of the catchment and the impermeable area survey or desktop assessment • Node Reference – The manhole on the hydraulic model to which the above loadings will drain
For most modelling situations and for large models in particular, it is not necessary to assign a sub-catchment to every node in the model.
2.2.5 Final Validated Model
Following construction and validation of the hydraulic model and inputting of the drainage sub-catchments, the model is ready for verification and further analysis.
2.3 Model Verification
Verification of the hydraulic models is essential to establish confidence in the physical data and in the loading data input into the model and hence, in the results predicted by the model. In order to confirm that the model correctly represents the real system these hydraulic models will be verified, with the use of flow and rainfall data. The model is verified for the following:
• Dry weather flow verification using 2 dry weather Events selected from the Flow and Rainfall Survey • Storm flow verification using 3 rainfall Events from the Flow and Rainfall Survey • Historical verification against documented and anecdotal evidence of flooding and surcharging
Athlone Waste Water Discharge Licence Application Details of Modelling of Discharges from the Agglomeration Attachment D1
Model verification against flow survey data is achieved by comparing the flows predicted by the model, when subjected to a known event, with the actual flows measured in the sewer network for the same event. Corrections are made to the model during the verification process only where the flow monitor is known to be recording accurately, and where the physical condition of the sewers and the contributing impermeable areas are independently checked. When agreement is achieved between the model and the flow survey or where a satisfactory explanation can be given for disparity in the results, the model is considered verified.
The Code of Practice For The Hydraulic Modelling of Sewer Systems (ref.3.1) states that the modelled flows/depths compared with the observed flows/depths should meet the following criteria:
1) Peak flow rate + 25 % to - 15 %
2) Volume of flow + 20 % to - 10 % over the period for which the observed flows are expected to be accurate
3) Surcharge should be +0.5 m to - 0.1 m
4) The general shape of the two hydrographs should be similar and should continue until substantial recession has occurred
If the above criteria are met for two out of the three rainfall storms, the Model may be considered verified.
2.3.1 Dry Weather Flow Verification
This process involves checking that the predicted diurnally varying dry weather flow discharge rate for the catchment matches the observed data from days when no rainfall was recorded. The procedure also includes checking that there is correlation between predicted and observed depths of flow. This is particularly useful as it can provide information on problems such as negative gradients and silt in pipelines, which are indicated in observed data when the depth of flow is greater than would be expected for the flow rate concerned. The model can thus be amended to incorporate such findings if there is supporting information to justify any variation to the original model data.
Dry weather flow verification also provides information obtained on the diurnal variation of dry weather flow. This information can be used to optimise catchment management, for example by using attenuation to reduce the flow to full treatment.
In addition, the dry weather flow verification will enable infiltration rates to be quantified throughout the system. Such a survey could lead to the identification of cost-effective means of significantly reducing the infiltration flows in the sewer system, thereby reducing the need for new pipework as part of proposed improvement options.
Athlone Waste Water Discharge Licence Application Details of Modelling of Discharges from the Agglomeration Attachment D1
It should be noted that due to restrictions in the flow monitoring equipment, it is usually impossible to adequately verify against dry weather flows for upstream monitors where the flows are very low (see accuracy range in Section 1).
2.3.2 Storm Flow Verification
The second stage in the verification process is storm flow verification, where recorded flows are compared with computer-predicted flows and depths at each of the flow monitor sites when the recorded rainfall is applied to the model. Models are normally verified using a minimum of three significant rainfall events, in accordance with the code of practice.
Verification is the iterative process of running the InfoWorks model and comparing plotted results to the observed data. Each run’s results are analysed and any legitimate changes are made to the sewer system data file to improve the correlation between predicted and observed.
Changes are only made to the sewer system model if there is supporting information to justify any variation to the original model data. The accuracy is ultimately dependent on the adequacy of the existing information, the accuracy of the flow survey data, the suitability of the recorded rainfall events and any limitations of the InfoWorks model in simulating the particular sewerage system.
It is considered inadvisable to force fit and possibly provide an invalid model to satisfy verification criteria. If the plot comparisons are obtained that are outside the accuracy required, detailed explanations will be provided why this is the case. It is then a judgement whether the factor of safety of the model should be increased to compensate and give a safer model.
2.3.3 Historical Verification
Verification with historical data is achieved by comparing known historical operational problems with model simulation results for a known range of storm intensities. This process involves discussions with local engineers, the town foreman and those staff involved with the day-to-day running of the sewerage scheme. Although it is impossible to exactly determine the size of the flooding etc involved, this process serves as a good indication of the overall accuracy of the model.
2.4 Hydraulic Analysis of the Existing System
Following verification of the sewer system hydraulic model, the existing system is analysed using 1-year and 5-year return period rainfall events, incorporating a critical duration assessment. This would highlight the existing weaknesses in the system and would address the level of protection of the existing system against flooding and surcharging from dry weather flow to extreme rainfall design storms, including an assessment of the existing overflow to receiving waters.
The hydraulic performance of the system is measured under three headings:
Athlone Waste Water Discharge Licence Application Details of Modelling of Discharges from the Agglomeration Attachment D1
• Public health / flooding • Structural Integrity • Receiving water quality
The performance of the existing systems will be assessed in accordance with the performance criteria, for the full range of design storms. This work would provide a complete picture of the capabilities of the systems.
At this stage the effect of the contribution to the system from stormwater and infiltration is also assessed. This will demonstrate the loss of capacity in the foul system, due stormwater ingress and readily demonstrate the effects of network rationalisation.
2.5 Identification of Remedial Works
With the use of the verified model of the existing collection systems it will be possible to identify the most appropriate course of action for network rationalisation:
• Removal and / or reduction of stormwater inputs to the foul system (having regard for the effect of this work on the stormwater and downstream receiving waters) • Maximisation of the Existing System Capacity – having regard to sedimentation problems, throttles in the system etc. • Augmentation of System Capacity – through duplication, storage etc.
The CCTV Survey and subsequent Sewer Defects Survey in conjunction with the data from the Impermeable Area Study will identify the precise localities where sewer remediation would be concentrated. The structural grading of the networks will provide a priority programming of remediation works for the study area.
2.6 Inclusion of Future Developments
Based on the requirements of the latest Westmeath and Athlone Development Plans, an assessment is made of the likely areas in and around the town, which are, or are likely to be, zoned for development in the lifetime of the project. With the scale of these proposed developments (residential and industrial), it is likely that demands on the collection systems will be substantial and these will need to be examined in a coherent and integrated manner.
Prior to any detailed analysis of upgrading works to the existing sewerage system, it is necessary to add the loadings from these future areas to the verified hydraulic model to ensure that any drainage solution will be able to cater for both existing and future loading scenarios. It is assumed for this Study that only the foul flows from future developments will be included in the model and that surface water runoffs will be dealt with through attenuation measures or other Sustainable Urban Drainage Systems (SUDS).
Athlone Waste Water Discharge Licence Application Details of Modelling of Discharges from the Agglomeration Attachment D1
2.7 Identification and Development of Optimum Drainage Solution
In consultation with Westmeath County Council a range of possible staged development scenarios will be identified and preferred options selected.
After adding in the future development areas into the verified hydraulic model of the existing system a number of drainage solutions to cater for existing and future loadings can be readily modelled. This work will be reported to the County Council for consultation and will include project programming and scheme costings.
Based on the feedback from Westmeath County Council the optimum drainage solution would be further developed. The proposed model of the catchment will provide appropriate sizing of the conduits and storage facilities required within the existing system, which will be able to cater for a range of development scenarios. Drainage routes for connection of future areas to the existing system will be identified. Any further required investigations necessary would be identified at this stage.
Furthermore we recognise that the impact of the surface water runoff due to the proposed substantial urbanisation of the town needs to be carefully considered. In this regard the stormwater system will be assessed in terms of existing capacity and the most appropriate stormwater management strategies.
2.8 Stormwater Management Strategy
We understand that a formal stormwater management strategy has not been adopted to-date for Athlone and environs. It is proposed to undertake to provide Westmeath County Council with a strategy to be applied to surface water discharges to sewers and watercourses from new developments. Such a strategy would result in the reduction of the frequency of flooding, especially during extreme rainfall events. Best management practices (BMP) for controlling stormwater runoff typically include:
• The reduction of flows entering the drainage system – with the use of detention basins, grass swales, porous paving etc. • The attenuation of flows entering the sewer or watercourse – with the use of roof storage etc. • Attenuation in the drainage system – with the use of oversized sewers, on-line tanks, off-line tanks etc.
The verified hydraulic model will be used to provide appropriate sizings for conduits, storage facilities etc.
Athlone Waste Water Discharge Licence Application Details of Modelling of Discharges from the Agglomeration Attachment D1
2.9 Environmental Impacts
As well as the provision of adequate conveyance measures to cater for the future flows, the verified hydraulic will be used to predict the volume and frequency of overflow from Combined Sewer Overflows (CSOs) and Pumping Stations to receiving waters. Recommendations will take full cognisance of all the relevant legislation.
3 HYDRAULIC MODELLING OF EXISTING SEWERAGE SYSTEM
3.1 Introduction
A detailed survey of over 3,100 manholes in Athlone was carried out by USA Ltd. The survey database was submitted in SUS25 format and converted to the InfoWorks format, where it was validated, verified and analysed. A description of these processes as applied to the Athlone model is included hereunder.
The initial manhole database contained a number of gaps and anomalies, the majority of which were reconciled by re-survey. Any remaining data problems were rectified in InfoWorks by inferring data from neighbouring manholes and pipes. Once all errors in the data were rectified, the model could then be verified.
The overall model of the Athlone sewer network is summarised in Table 3.1 Table 3.1 Existing Model Details
FOUL / SURFACE MODEL ITEM TOTAL COMBINED WATER Manholes (No.) 1,790 1,319 3,109 Sewers (m) 68,693 57,660 126,352 <=225 (m) 45,457 20,717 66,174 225 – 300 (m) 10,223 9,339 19,562 300 – 450 (m) 6,492 8,090 14,582 450 – 600 (m) 4,109 5,937 10,046 600 – 750 (m) 956 2,501 3,457 >750 (m) 1,456 11,076 12,532 Sub-Catchments (No.) 907 742 1,649 Pumping Stations (No.) 10 0 10 Overflows (No.) 10 0 10 Outfalls (No.) 13* 44 57
* - Includes Outfalls from CSOs and Pumping Stations
Athlone Waste Water Discharge Licence Application Details of Modelling of Discharges from the Agglomeration Attachment D1
3.2 Foul/Combined Sewer System
The Athlone Main Drainage area is served by a single foul drainage system which combines gravity sewers and pumping stations and which outfalls to a main pumping station at Golden Island from where all flows are pumped to a wastewater treatment plant at Loughandonning south east of the town. Although many of the newer estates on the environs of the town are drained separately (i.e. surface water runoff discharging to surface water sewers), much of the older part of the town towards the centre is partially or fully combined and must cater for storm flows as well as foul loading.
The main catchments are described hereunder;
3.3 West Side
The Urban Council Area on the west side of the Shannon is served by a combined pumped and gravity system which discharges to the head of a twin siphon pipeline under the Shannon and onwards to the Golden Island Pumping Station. The west side catchment can be considered to consist of 3 sub-catchments that area.
3.3.1 West Side / Canal Sewer
A gravity sewer runs from the western extremity of the town on the Galway Road, over 3km and eventually connects into the siphon. The sewer ranges in size from 225mm to 450mm at its outfall. It runs west east along the Galway Road before turning south and running alongside the Canal over a distance of 1200m approximately. The last section of sewer runs through marshy ground (River Shannon flood plain) and outfalls into the siphon chamber on the west bank of the river. There are 3 overflows off the sewer into the Canal and one overflow at the Siphon inlet chamber described further in this section.
The sewer serves all of the roadside properties on the Galway Road and a number of estates (Ardbrae, Iona Park, Battery Heights) en route. It also serves the Deer Park Road/Parnell Square catchment. Included in this is another overflow on Deer Park Road to the Shannon.
3.3.2 West Side Pumping Station
A gravity sewer runs from John Mitchell’s Terrace/Battery Heights for a distance of 1200m before outfalling into the recently constructed West Side Pumping Station, located off Clonoun Road adjacent to the Canal. The sewer ranges in size from 225mm to 400mm at its outfall into the pumping station. The pumping station, which described further in this Section, pumps foul flows forward to the siphon chamber on the west bank of the Shannon.
The sewer serves part of the Battery Heights Estate as well as John Mitchell’s Terrace, Ave Maria Terrace, St. Anne’s Terrace, St. Paul’s Terrace.
Athlone Waste Water Discharge Licence Application Details of Modelling of Discharges from the Agglomeration Attachment D1
3.3.3 West Bank Pumping Station
A gravity sewer runs over a distance of 1000m from the Railway bridge, along the front of the Barracks on Grace Road, along The Quays and outfalls into the West Bank Pumping Station, located adjacent to the lock gates on the Shannon. The pumping station, described further in this Section, pumps foul flows forward to the siphon chamber on the west bank of the Shannon. The sewer, also known as the West Bank culvert, is mainly of old brick construction and is predominantly egg- shaped. The sewer ranges in size from a 1200 x 820mm arch to a 940 x 550mm oval at its outfall. There is a high level overflow to the Shannon immediately upstream of the West Bank pumping station, which limits the flow into this facility.
There are a number of problems associated with this sewer, not least of which is the degree of infiltration of ground water into the sewer which causes overloading of the West Bank pumping station during the winter months.
The sewer serves the Barracks and other properties on Grace Road as well as Barrack Street, High Street and Excise Street.
3.4 East Side
The Urban Council Area on the west side of the Shannon is served by a combined pumped and gravity system which eventually discharges into the Golden Island Pumping Station. The east side catchment can be considered to consist of 4 sub- catchments.
3.4.1 Abbey Road/Coosan West
This area is served by a gravity sewer that runs north-south along Coosan Road under the bypass and outfalls into Coosan West pumping station. From there all flows are pumped to the head of a gravity sewer in Tormey Villas which runs southwards along Coosan Road before outfalling into Abbey Road pumping station. The sewer ranges in size from 150mm to 300mm at its outfall into Abbey Road. There is one overflow off the sewer downstream of the Coosan West rising main connection. This and the Coosan West pumping station are described further on in this Section.
The sewer serves all of the properties along Coosan Road as well as Priory Park, Clonbrusk Estate and Assumption Road.
3.4.2 Abbey Road/Coosan East
This area is served by a gravity sewer which runs northeast-southwest from Two Mile Road to the north of the bypass, runs under the bypass and outfalls into Coosan East pumping station, which is located off Coosan Point Road immediately south of the bypass. From there all flows are pumped to the head of a gravity sewer further south along Coosan Point Road - this sewer then runs southwards through
Athlone Waste Water Discharge Licence Application Details of Modelling of Discharges from the Agglomeration Attachment D1
Beechpark Estate, Auburn Drive and Coosan Point Road before outfalling into Abbey Road pumping station. The sewer ranges in size from 150mm to 525mm at its outfall into Abbey Road.
The sewer serves all of the properties along One Mile Road north of the bypass and a number of estates along Coosan Point Road (Arcadia, Beechpark, Auburn Drive). A secondary gravity sewer serves the Ballymahon Road and One Mile Round and outfalls into the main sewer in Beechpark.
3.4.3 Abbey Road/Burgess Park
Abbey Road pumping station consists of foul and storm wet wells, separated by a weir. While the storm pumps convey excess storm flows directly to the Shannon, foul flows are pumped to the head of a gravity sewer on Northgate Street which runs from there, along the Strand and Burgess Park before outfalling into Golden Island pumping station. As well as the 2 catchments described above there is another gravity sewer entering the Abbey Road facility serving the St Brigids Terrace, St Francis Terrace estates off Lucas Lane and also serving Northgate Street. As well as storm pumps, there are 2 high level overflows in or adjacent to the Abbey Road facility – these are described later. There is also an overflow in Burgess Park on the downstream gravity sewer which overflows excess storm flows to the Shannon.
The downstream gravity sewer, which ranges from 300mm diameter at the connection of the Abbey Road rising main, to 600mm at its outfall serves the Strand and Church Street areas as well as Griffith Street and Burgess Park.
3.4.4 St Mel’s Culvert
The newer development areas east of the town drain through a series of trunk sewers constructed as part of the Athlone Main Drainage Scheme designed by P.H. McCarthy & Partners and completed in 1994.
The St Mel’s Culvert runs from St Mel’s Park off Love lane immediately south of the railway line, along Love Lane, Lower Road, and Costello Street before outfalling into Golden Island pumping station. The sewer is approximately 900mm in diameter over its 1200m length. There are a number of overflows from this culvert to a higher level parallel surface water culvert.
The culvert serves much of the east of the town including the Auburn Heights and Retreat Park area, Brideswell and Castlemaine Street.
3.4.5 South East
A gravity sewer runs from the Dublin Road and Garrycastle Bridge in the south eastern extremity of the town and outfalls into the St Mel’s culvert immediately upstream of Golden Island. The sewer varies in size from 150mm to 600m at its outfall.
Athlone Waste Water Discharge Licence Application Details of Modelling of Discharges from the Agglomeration Attachment D1
The culvert serves the south east of the town including the Willow Park area, Cartrontroy Heights, Esker Glen and Brooklawn.
3.5 Surface Water Sewer System
The surface water system consists of approximately 40 separate networks ranging from a maximum network of approximately 200 manholes to single pipe outfalls. As mentioned earlier, most separate drainage occurs in the eastern part of the town with much of the centre and western areas being partially or fully combined.
The main surface water outlets to the Shannon are:
• A stream that flows from Garrycastle in a westerly direction north of the railway and enters the Shannon. Much of this stream has been culverted through the new development areas. As part of the Main Drainage Scheme this stream was intercepted at St. Mel’s Park north of the town and flows were diverted to a new box culvert that discharges to the Shannon at Golden Island. This is connected via a series of overflows to the St Mel’s foul culvert that runs parallel.
• The Garrycastle Stream that commences at Crosswood about 5 to 6 kilometres east of Athlone. The stream crossed the Dublin Road at Garrycastle Bridge and drained through Bunnavalley skirting the southern limit of developed parts of the urban and county areas eventually entering the Shannon at Golden Island south of the town.
3.6 Sub-Catchments
The overall area of the Athlone catchment is approximately 1,300 hectares. The catchment is divided into approximately 1650 sub-catchments as follows:
• 900 foul sub-catchments containing information on population, infiltration flows and industrial trade flows • 750 storm sub-catchments with information on impermeable and permeable runoff areas contributing to both the foul and surface water sewerage systems The amount of area draining to each system was estimated from the following sources:
• on-site walkover survey, • Aerial Photography, • Flow Survey, • CCTV Survey of connections.
3.7 Pumping Stations
Athlone Waste Water Discharge Licence Application Details of Modelling of Discharges from the Agglomeration Attachment D1
The network consists of a number of pumping stations, eleven of which were included in the model.
3.7.1 West Bank Pumping Station
The West Bank Pumping Station is located on the west side of the River Shannon and the Canal. The pumping station serves approximately 600 P.E. The pumping station has two submersible pumps, duty and standby. The pump rate is estimated at 33 l/s pumping to the siphon across the River Shannon to the Golden Island Pumping Station. The Pumping Station Survey reported that the pumping station was in poor condition with debris present in the wet well affecting the operation of the pumps. The survey also reported that the non-return valve sticks on occasion.
3.7.2 West Side Pumping Station
The West Side Pumping Station is located on the west side on the banks of the River Shannon on ‘The Quay’. The pumping station was constructed in 2001. The pumping station serves approximately 1060 P.E. The pumping station has two pumps, duty and standby with a 2 wet well construction. The pump rate is estimated at 42 l/s pumping to the siphon across the River Shannon to the Golden Island Pumping Station.
3.7.3 Woodville Grange Pumping Station
The Woodville Grange Pumping Station is located north east of Athlone in the townland of Lissywollen. The pumping station serves approximately 200 P.E. The pump rate is estimated at 5 l/s pumping to the combined 300mm diameter sewer upstream of the relief road.
3.7.4 Abbey Road Pumping Station
The Abbey Road pumping station is located in Abbey Road next to the Marina and the River Shannon. The pumping station serves approximately 6800 P.E. The Abbey Road Pumping Station consists of foul and storm wet wells, separated by a weir. Foul flows are pumped to the head of a gravity sewer on Northgate Street which runs from there, along the Strand and Burgess Park into Golden Island Pumping Station. The storm pumps convey excess storm flows directly to the Shannon. The foul wet well has two pumps operating single duty only. The pump rate is estimated at 58 l/s. The storm wet well one storm pump with a pump rate estimated at 93 l/s pumping to the River Shannon. The Abbey Road Pumping Station is generally in poor condition with debris around the site and insecure covers. Cleaning and maintenance of the wet wells is difficult.
3.7.5 Coosan East Pumping Station
The Coosan East Pumping Station is located north of Athlone in the townland of Coosan. The pumping station serves approximately 740 P.E. The pumping station has two submersible pumps, duty and assist. The pump rate is estimated at 9 l/s
Athlone Waste Water Discharge Licence Application Details of Modelling of Discharges from the Agglomeration Attachment D1
pumping to a 225mm diameter sewer contributing to the Abbey Road Pumping Station. The pumping station is generally in good condition however the overflow flap valve is fixed open.
3.7.6 Coosan West Pumping Station
The Coosan West Pumping Station is located north of Athlone in Tormey Villas off Coosan Road. The pumping station serves approximately 1280 P.E. The pumping station has two submersible pumps, duty and assist. The pump rate is estimated at 12l/s pumping to a 225mm diameter sewer contributing to the Abbey Road Pumping Station. The pumping station is generally in good condition however the control kiosk is in poor condition.
3.7.7 Golden Island Pumping Station
The Golden Island Pumping Station is located south of Athlone. The pumping station serves approximately 18090 P.E. pumping all flows from the Athlone network to the Wastewater Treatment Works. The pumping station has two pumps, duty and standby with a two well construction. The pump rate is estimated at 209 l/s. The pumping station was constructed in 1994 but much of the automatic equipment is now unserviceable. There is space for a further pump.
3.7.8 Mayfield Grove Pumping Station
The Mayfield Grove Pumping Station is located in the north east of Athlone in Mayfield Grove. The pumping station serves approximately 312 P.E. The pumping station has two submersible pumps, duty and assist installed in 1998. The pump rate is estimated at 9 l/s pumping to a 225mm diameter sewer contributing to the Abbey Road Pumping Station. There is no benching in the wet well due to previous damage to the pumping station.
3.7.9 Priory Park
The Priory Park Pumping Station is located north of Athlone in Priory Park off Coosan Road. The pumping station serves approximately 150 P.E. The pump rate is estimated at 2l/s pumping to a 225mm diameter sewer contributing to the Abbey Road Pumping Station.
3.7.10 Roscommon Road
The Roscommon Road Pumping Station is located opposite No.1 Roscommon Road, north west of Athlone. The pumping station serves approximately 60 P.E. The pumping station has two submersible pumps, duty and standby. The pump rate is estimated at 6 l/s pumping to a 450mm diameter sewer contributing to the Canal Sewer. The pumping station is generally in poor condition with an overgrown site and insecure covers and control panel.
Athlone Waste Water Discharge Licence Application Details of Modelling of Discharges from the Agglomeration Attachment D1
3.8 Overflows
A number of overflows were surveyed. The overflows have all been included in the model, as follows:
3.8.1 Upper Canal Overflow, Iona Park, West Side
The Iona Park overflow is one of three overflows to the Canal. The overflow is located in Iona Park north west of Athlone. The spill flows overflow from the 450mm diameter Canal Sewer over a weir and static screen.
3.8.2 Mid Canal Overflow, Galway Road, West Side
The second canal overflow to the canal downstream of Iona Park is located by the bridge on the Galway Road. The spill flows overflow from the 450mm diameter Canal Sewer via a high level overflow pipe.
3.8.3 Lower Canal Overflow, Clonoun Road, West Side, upstream of Siphon
The Clonoun Road overflow to the canal at the lower end of the Canal Sewer is located upstream from the siphon. The spill flows overflow from the 450mm diameter Canal Sewer via a high level overflow pipe.
3.8.4 Siphon Overflow, West Side
There is an overflow located immediately upstream of the siphon spilling to the River Shannon. The spill flows overflow from the 450mm diameter sewer over a weir and through a non return valve. A slice valve controls the flow to the siphon, allowing all flows to overflow directly to the River Shannon if this value is closed.
3.8.5 Magazine Road Industrial Estate Overflow
An overflow located in the Industrial Estate off Magazine Road overflows to the River Shannon. The spill flows overflow from the 225mm diameter foul sewer over a weir.
3.8.6 Deer Park Road Overflow, West Side
The overflow is located adjacent to No.9 Deer Park Road. The spill flows overflow from the 375mm diameter foul sewer over a weir. West Bank Pumping Station Overflow
The West Bank Pumping Station is located on the west side of the River Shannon and the Canal. During significant rainfall events when the pump capacity is exceeded flows surcharge back to the overflow upstream. The spill flows overflow via a non return value.
Athlone Waste Water Discharge Licence Application Details of Modelling of Discharges from the Agglomeration Attachment D1
3.8.7 Abbey Road Pumping Station Overflow
The Abbey Road pumping station is located in Abbey Road next to the Marina and the River Shannon. The Abbey Road Pumping Station consists of foul and storm wet wells, separated by a weir. The storm wet well has one storm pump with a pump rate estimated at 93 l/s pumping to the River Shannon.
3.8.8 Coosan East Pumping Station Overflow
The Coosan East Pumping Station is located north of Athlone in the townland of Coosan. During significant rainfall events when the pump capacity is exceeded flows overflow to the Athlone Bypass Drain which discharges to the River Shannon.
3.8.9 Coosan West Pumping Station Overflow
The Coosan West Pumping Station is located north of Athlone in Tormey Villas off Coosan Road. During significant rainfall events when the pump capacity is exceeded flows overflow to the Athlone Bypass Drain which discharges to the River Shannon
3.8.10 Coosan Road Overflow
The Coosan Road overflow is located downstream of the Coosan West Pumping Station on Coosan Road. The spill flows overflow from the 300mm diameter foul sewer over a weir.
3.8.11 Burgess Park
The Burgess Park overflow is located in Burgess Park upstream from the Golden Island Pumping Station. This is the only overflow for the Golden Island Pumping Station. During significant rainfall events when the pump capacity is exceeded flows surcharge back to the overflow upstream. The spill flows overflow from the 600mm diameter sewer over a weir and through a non return valve. A slice valve controls the flow to the pumping station, allowing all flows to overflow directly to the River Shannon if this value is closed.
3.8.12 Roscommon Road Pumping Station
The Roscommon Road Pumping Station is located on Roscommon Road on the west side of Athlone west of the canal. During significant rainfall events when the pump capacity is exceeded flows overflow via a high level non return valve to a 600mm surface water sewer discharging to a surface water drain 400m west of the canal. . 3.8.13 Northgate Street SWO
Northgate Street SWO is located in Northgate Street upstream of Abbey Road. The spill flows overflow from the 300mm diameter sewer via a high level 300mm diameter overflow sewer, approximately 140m, to the River Shannon
Athlone Waste Water Discharge Licence Application Details of Modelling of Discharges from the Agglomeration Attachment D1
3.8.14 Lower Road SWO
Lower Road SWO is located in Lower Road north of Golden Island. The SWO is on the 750mm diameter foul sewer in St. Mel’s Culvert. The spill flows overflow from the 750mm diameter sewer via a high level non return valve to the 3m by 1.6m storm sewer in St. Mel’s Culvert. The storm sewer in St. Mel’s Culvert discharges to the Al River at Golden Island approximately 560m upstream of The River Shannon.
3.8.15 Lower Road/Castlemaine Street SWO
Lower Road/Castlemaine Street SWO is located in the junction of Lower Road and Castlemaine Street north of Golden Island. The 450mm diameter sewer on Castlemaine Street connects at a high level to the 750mm diameter foul sewer in St. Mel’s Culvert. The spill flows overflow from the 450mm diameter sewer via a high level non return valve to the 3m by 1.6m storm sewer in St. Mel’s Culvert. The storm sewer in St. Mel’s Culvert discharges to the Al River at Golden Island approximately 560m upstream of The River Shannon.
3.8.16 Castlemaine Street SWO
Castlemaine Street SWO is located in Castlemaine Street east of Golden Island. The spill flows overflow from the 375mm diameter sewer via a high level pipe to the Al River at Ankers Bower approximately 760m upstream of The River Shannon.
3.8.17 Love Lane SWO
Love Lane SWO is located in Love Lane adjacent to St. Mel’s Park. The 450mm diameter sewer on Love Lane connections at a high level to the 750mm diameter foul sewer in St. Mel’s Culvert. The spill flows overflow from the 450mm diameter sewer via a non return valve to the 3m by 1.6m storm sewer in St. Mel’s Culvert. The storm sewer in St. Mel’s Culvert discharges to the Al River at Golden Island approximately 560m upstream of The River Shannon. .
3.8.18 West Bank Pumping Station SWO
The West Bank Pumping Station is located on the west side of the River Shannon and the Canal. During significant rainfall events when the pump capacity is exceeded flows surcharge back to the overflow upstream. The spill flows overflow via a non return value. There is also a high level non return valve.
3.9 Verification of Existing Hydraulic Model
Model Verification against flow survey data is achieved by comparing the flows predicted by the model, when subjected to a known event, with the actual flows measured in the sewer network for the same event.
Athlone Waste Water Discharge Licence Application Details of Modelling of Discharges from the Agglomeration Attachment D1
3.9.1 Historical Verification
The performance of the hydraulic model of the existing system has been analysed under design rainfall conditions to identify its hydraulic weaknesses under existing loading conditions.
The verified model showed that there were a number of overflows operating frequently and there were a number of areas in Athlone where the potential for flooding exists.
Discussions with local staff from both Westmeath County Council and Athlone UDC confirmed that the following sites are problematic
• Flooding of Lower Road/Retreat Park • Flooding of The Strand • Flooding of Deer Park Road • Flooding of Coosan Point Road/St. Kieran’s Terrace • Flooding of Mayfield Grove • Infiltration to the West Bank Pumping Station • Overflows from Abbey Road Pumping Station • Overflows from Burgess Park • Surcharging upstream of the Golden Island Pumping Station
The verified model is predicting the known problems in the network of overflows, flooding and surcharging. This increases confidence in the model.
Athlone Waste Water Discharge Licence Application