{"text_format":"1","workbook":"xlsx","n_sheets":9,"sheets":["Cover Sheet","Introduction & Conclusion","1.Risk assessment","2.Total vol. - Mitigation","3.Containment volume-Total vol.","4.Current asset evaluation","5.Containment type-Total vol.","Template Settings","Settings"],"not_rendered":{"charts":0,"images":26,"macros":1,"external_links":1,"defined_names":58,"comments":1,"pivot_tables":0},"unopened":[],"bounds":{"document_bytes":16777216,"sheet_cells":100000,"rows_first":2000,"rows_last":500,"rows_between":2000,"halvings":0,"cell_chars":16384,"cell_head_chars":4096},"cells_cut":0,"cells_raw":0,"read":"whole","date_system":"1900"}

{"sheet":"Cover Sheet","index":0,"n_rows":43,"n_cols":11,"rows_kept":43,"cut":false,"hidden":false,"merged":[[47,2,47,4],[48,2,48,4],[49,2,49,4],[42,2,42,4],[43,2,43,4],[44,2,44,4],[45,2,45,4],[46,2,46,4],[41,2,41,4],[26,1,27,1],[26,2,26,4],[26,5,26,7],[34,1,34,7],[35,1,35,2],[35,3,35,5],[35,6,35,7],[36,1,36,2],[36,3,36,5],[36,6,36,7],[38,1,38,7],[40,2,40,4],[25,2,25,7],[18,1,18,5],[18,6,18,7],[19,1,19,5],[19,6,19,7],[20,1,20,5],[20,6,20,7],[22,1,22,7],[23,1,23,3],[23,4,23,7],[24,1,24,3],[24,4,24,7],[15,1,15,5],[15,6,15,7],[16,1,16,5],[16,6,16,7],[17,1,17,5],[17,6,17,7],[13,3,13,7],[2,2,2,7],[3,2,3,7],[5,2,5,3],[5,5,5,7],[6,2,6,3],[6,5,6,7],[7,2,7,3],[7,5,7,7],[8,2,8,3],[8,5,8,7],[9,2,9,3]]}
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[null,"Project Information"]
[null,"Workbook Name:","IED Risk Register-Fullerton"]
[null,"Project Title:","SWS EMA - Lot 8 - EIA "]
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[null,"Section:","Industrial Emission Directive Permit",null,"Divn/Dept:",null,null,null,"Please select from the dropdown or for enter manually"]
[null,"Subject:","Risk Assessment",null,"Project Nr:",790101]
[null,"Project Manager:","Daniel Watson",null,"File Ref:","790101-MMD-IED-FUL-CA-C-001","790101-MMD-IED-CA-C-004","790101-MMD-IED-CA-C-004","Please use the format Project Number/PIMS Unique number (e.g. 123456/5) or project specific format"]
[null,"Originator","Tom Reynolds",null,"Calc Nr:"]
[null,"Checker","Anita Manns",null,"Nr Sheets:",5,null,null,"This is updated automatically as sheets are added/removed"]
[null,"Template Version","E"]
[null,"Design Phase"]
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[]
[]
[null,"Computer Applications Used",null,null,null,null,"Version/Date",null,"Please enter any other programs used as part of the calculation"]
[null,"Microsoft Excel",null,null,null,null,2108]
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[]
[]
[]
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[null,"Scope of Checking"]
[null,"Manual calculations",null,null,"Computer generated calculations"]
[null,null,null,null,null,null,null,null,"Enter a description of the checks that are required/have been performed"]
[]
[null,"Sheets","Calculations by",null,null,"Checked by"]
[null,null,"Name","Signature","Date","Name","Signature","Date","Please keep an audit list of the authors and checkers of each calculation sheet"]
[292574555,"1.Risk assessment","Hari Prasath","HP","2022-08-05","Ashwin Powar","AP","2022-08-05"]
[292575378,"2.Total vol. - Mitigation","Hari Prasath","HP","2022-08-05","Ashwin Powar","AP","2022-08-05"]
[292576031,"3.Containment volume-Total vol.","Hari Prasath","HP","2022-08-05","Ashwin Powar","AP","2022-08-05"]
[292576417,"4.Current asset evaluation","Hari Prasath","HP","2022-08-05","Ashwin Powar","AP","2022-08-05"]
[292576606,"5.Containment type-Total vol.","Tom Reynolds","TR","2025-01-22","Anita Manns","AM","2025-01-22"]
[]
[null,"Approved by"]
[null,"Approver",null,"Signature",null,null,"Date"]
[null,"Tom Reynolds",null,"TR",null,null,"2024-02-21"]
[]
[null,"Version History"]
[null,"Version","Description",null,null,"Originator","Checker","Date"]
[null,"P01","Initial Calculation",null,null,"Hari Prasath","Ashwin Powar","2022-08-15",null,"Latest Version","P03"]
[null,"P02","Worksheet 6 added by SW to reflect revised solution following additional spill modelling and cost estimation activities.",null,null,"Tom Reynolds","Tom Reynolds","2024-02-26",null,null,"2025-01-22"]
[null,"P03 ","Worksheet 6 consolidated into worksheet 5 for clarity.\nTank list added to worksheet 3. \nOther minor amendments to feedback.",null,null,"Tom Reynolds","Anita Manns","2025-01-22",null,"Last Checked","2025-01-22"]

{"sheet":"Introduction & Conclusion","index":1,"n_rows":22,"n_cols":3,"rows_kept":22,"cut":false,"hidden":false,"merged":[]}
[]
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[null,"Introduction"]
[null,"The IED permit application requires an assessment of the stored capacity, risk arising from a spill scenario and identification secondary containment solution to mitigate the risk.","Please introduce what this spreadsheet is"]
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[null,"Purpose"]
[null,"The aim of the study is to support Southern Water’s permitting and sludge treatment strategy","Please enter the purpose of the spreadsheet"]
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[null,"Required Output"]
[null,"A high-level desktop-based risk assessment using the ABDA classification tool to calculate the sites overall risk rating based on a Source-Pathway-Receptor Analysis. \nIdentification of appropriate containment solution.","Please define what the outputs of the spreadsheet should be"]
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[null,"Conclusions"]
[null,"The preferred option is outlined on worksheet 5 and comprises a number of local bunds.\n","If the spreadsheet/calculation has a conclusion please enter it here"]
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[null,"Assumptions"]
[null,"CIRIA 736 Proposal amended 201221, Clause 3.2 study, Points (7-18), Page 7.\n\n1.The failure risk is assessed for a Single tank\n2.Only the above ground volume is considered for failure","Please ensure all assumptions are stated\nPlease specify any assumptions that apply to the whole spreadsheet\nAssumptions on single sheets should be placed on the sheet\nAssumptions on a cell or range should be put next to the cell or in a comment on top of it"]
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[null,"Basic Design Information or Source and Reference"]
[null,"CIRIA report C736"]
[]
[]
[null,"Identify documents/technical records where output will be used"]

{"sheet":"1.Risk assessment","index":2,"n_rows":91,"n_cols":12,"rows_kept":91,"cut":false,"hidden":false,"merged":[[42,9,47,9],[43,1,43,2],[43,3,43,4],[44,1,44,2],[44,3,44,4],[41,1,41,2],[41,3,41,4],[42,1,42,2],[42,3,42,4],[42,8,47,8],[45,1,45,2],[45,3,45,4],[46,1,46,2],[46,3,46,4],[47,1,47,2],[47,3,47,4],[71,3,71,9],[48,1,48,2],[48,3,48,4],[49,1,49,2],[49,3,49,4],[50,3,50,4],[63,1,63,2],[66,3,66,9],[67,3,67,9],[68,3,68,9],[69,3,69,9],[70,3,70,9],[72,3,72,9],[73,3,73,9],[74,3,74,9],[82,1,82,2],[87,1,87,2]]}
[]
[1.1000000000000001,"Source"]
[]
[null,"Material","Physical properties","Maximum quantity","units","Storage","Flammability","Corrosive","Ecotoxicity (based on LD and quantity)","Hazard rating "]
[null,"Sludge Reception tank 01\n(picked as example, illustrative of wider site)","Sludge","265 m3 (approximately) - total volume for tank\n\n[As per IED Permit, Main Supporting Document 790101_MSD_Main_FUL,Page 3]","m3","Steel tank ","Medium","Low","Organic heavy - Nitrogen, \nPhosphorous, Ammonia, BOD, TSS, COD - Environmental hazard (algae blooms and death of organisms)\n\nPathogens - Human hazard (E.coli etc.)","M"]
[null,null,null,null,null,null,null,null,"Overall","M"]
[]
[1.2,"Pathway and Receptor"]
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[null,"Figure 1.1 Site Layout with Source-Pathway-Receptor",null,null,null,null,null,"Figure 1.2 Site picture of Sludge Reception tank 01"]
[]
[]
[null,"Pathway - the route from primary containment to receptor (extent of loss of containment)",null,"Time of concentration/ duration of source outside containment",null,"Hazard - Transport potential ",null,null,"Receptor","Hazard - Damage potential"]
[null,"The surrounding superficial alluvium and River Terrace deposits to the south and west have both been designated as Secondary A aquifers. The head deposits to the southeast have both been designated as a Secondary (undifferentiated) aquifer.\n\n[As per IED Permit, Site Condition report 790101_MSD_SCR_FUL,Page 3]",null,"Direct contamination but over an extended period of time",null,"M",null,null,"The River Anton is located 40m west of the site area, flowing south and joining the River Test 3.5 km downstream which in turn flows into the English Channel.A drain is present 10m west of the site and flows into the River Anton. North east  of the site (approximately 165m away), a drain associated with the disused oil well formerly operated by Star Energy Oil Uk Ltd is present exclusively within that site.\n\n\n[As per Site Condition Report 790101_MSD_SCR_FUL, Hydrology and flooding, Page 3]","H"]
[null,"If the permeable area were to get saturated (high groundwater) or became blocked with sludge, areas will act as impermeable and transport sludge downstream.",null,"Direct contamination but over an extended period of time",null,"M"]
[null,"The site is located in flood zone 1 and is at very low risk of flooding from rivers or sea.\n \n[As per IED Permit, Climate Change Risk Assessment, 79010_ERA_CCRA_FUL,Page 12]",null,"Direct contamination",null,"M"]
[null,"Existing underground services - ductwork, tunnels etc. (locations not known)",null,"Direct contamination but over an extended period of time",null,"L"]
[null,"Existing underground sludge pipework",null,"Direct contamination but over an extended period of time",null,"M"]
[null,"There is impermeable road surfacing around the tanks. Ground naturally drains to this area\n\nIf inventory is lost or cascaded onto the road (saturated permeable ground), sludge will be transported through the drainage channel to the head of the wastewater treatment works",null,"Minutes - hours",null,"L"]
[null,"If the drainage channel were to get blocked,  it may overflow locally to the permeable surrounding area.",null,"Minutes - hours",null,"M",null,null,"The site falls with two nitrate vulnerable zones; Hampshire Chalk (groundwater) and Hamble Estuary eutrophic NVZ (Trac) (eutrophic water). The decommissioned Test Valley environmentally sensitive area lies 131m southwest of the site. \n\n[As per Site Condition Report 790101_MSD_SCR_FUL,Sensitive land use, Page 3]","H"]
[null,"Risk of surface flooding on the site. The majority of the site is predominantly at a very low risk (<0.1% chance of flooding per year). However, several of the tanks as well as some isolated areas of the site are at medium (1-3.3%) or high (>3.3%) annual risk of flooding.\n\n[As per Climate Change Risk Assessment,790101_ERA_CCRA_FUL, Page 12]",null,"Minutes - N/A (dependant on flooding extent)",null,"M",null,null,"The majority of the site is \npredominantly at a very low risk (<0.1% chance of flooding per year) according to Environment Agency flood risk maps. However, several of the tanks as well as some isolated areas of the site are at medium (1-3.3%) or high (>3.3%) annual risk of flooding. This creates a risk that vital infrastructure becomes flooded as well as the risk of reduced access to some areas of the site.\n\n[As per Climate Change Risk Assessment,790101_ERA_CCRA_FUL, Page 9]","M"]
[null,null,null,"Overall",null,"M",null,null,"Overall","H"]
[]
[]
[null,"*Flooding in flood zone 3 only have a 1 in 100 year probability of happening in a year"]
[]
[]
[null,"Combination of Hazards",{"$f":"J6&F51&J51","v":"MMH"}]
[]
[]
[null,"Overall risk rating for zone (Ciria 736) ","H"]
[]
[]
[]
[1.3,"Frequency of loss of containment"]
[]
[]
[null,"Failure mode","Description","Existing consequence and mitigation measure",null,null,null,null,null,null,"Annual probability of loss of containment","Rating"]
[null,"Operational failure - tank (partial)","Overfilling/overflow of tank\n\nFoaming","Sludge is imported to the Site by tankers from approximately 30 sites on average by 5-6 29 m3 tankers daily. It is stored with the indigenous sludge in 2 No. sludge reception tanks before being pumped through 2 No. strain presses to 2 No. screened sludge storage tanks. In the event of overfilling/overflow or foaming conditions, the site is manned (7am – 5pm on weekdays, 7am – 1pm on Saturdays and 7am – 11am on Sundays) and so any loss of containment can be dealt with immediately and with tankers being on site within 2hrs, as part of an emergency response KPI with local tanker operator MTSR. Spills out of hours can be attended to within 1 hr.\n\nBoth clean and contaminated surface water is directed to a pumping station which recirculates it back into the system. The stormwater drainage of potentially contaminated areas from within the Site boundary is routed into the head of the works with no discharge outside of the site boundary. This allows site operations some time to deal with the leaks from operational failures. Flows exceeding the drainage system capacity will require mitigation with an improved inspection regime to catch spills prior to becoming significant.",null,null,null,null,null,null,"1 in 100 to 1 in 1 Million","M"]
[null,"Structural failure - tank (catastrophic)","Catastrophic failure due to significant external damage\n\nPotential to lose total volume if mixer pipework fails/break off of tank - has been a failure mode for digesters in the past","The tank is primarily located above ground with some portion below ground. For any loss of containment below ground, the sludge liquid will percolate into the permeable soil at a slow rate over a long period if not detected by the level or temperature alarms.\n\nIn the case of significant damage above ground, the total volume contained above ground could spill. \n\nIn the event of a catastrophic failure, sludge would flow in all directions. The sludge would predominantly flow to the southern boundary. There is an existing natural ground slope along the road towards the southern boundary where the sludge will flow by gravity.",null,null,null,null,null,null,"1 in 100 to 1 in 1 Million","M"]
[null,"Structural failure - tank (partial)","Most likely through defects formed in steel\n\nMost critical defects would at low level along the side of the tank walls or tank base. \n\nDefects would need to be large >6mm to allow for sludge to pass through freely. General screens at WwTW are 6-10mm, thus defects would need to be in the same range to allow for sludge to pass freely.\n\nRoof failure","Partial structural failure of the tank would mainly be through surface defects.  In the case of significant defects forming above ground, the volume contained above ground would seep through the defects. If the defects are significant, the tank could potentially lose the above ground volume over a long period of time if the level and temperature alarms are not functioning. However, this is unlikely. \n\nDue to operational presence on site, large drops in levels in the tanks and significant leaks above ground would be noticed. Significant defects below/above ground would also be easily spotted during the daily visual inspections. \n",null,null,null,null,null,null,"1 in 100 to 1 in 1 Million","M"]
[null,"Structural failure - pipework (catastrophic)","Loss of containment due to failure of above ground connecting pipework and rising mains","In the unlikely event where the above ground rising mains to the tank, heatamix pipework or de-gritting pipework fails and breaks off, a significant volume would spill out. Tanks have level and temperature alarms and so any required valve could be immediately shut off by operational staff.\n\nThe consequence of a catastrophic failure of containment is it's able to flow in all directions. Based on topography, sludge will cascade towards the south and eventually into the drainage system.\n\nTotal loss of containment is unlikely. A partial loss of containment would be more likely to occur.",null,null,null,null,null,null,"1 in 100 to 1 in 1 Million","M"]
[null,"Structural failure - pipework (partial)","Loss of containment most likely to occur where there are weak points in the pipework - Most likely through failures where pipe connects with the structure, bolts/sealant at pipe flanges/valves or along any pipe pitting.\n\nWeak point could be created through either human damage (during maintenance/operation), erosion (high velocities and silt content within the pipe) or environmental (corrosion)\n\nValve failure/seizure","Majority of pipework and connections are located above ground. Some of the pipework is located below ground or within the chambers below ground. \n\nIf loss of containment occurs underground (through leaks, joints and seals), sludge will percolate into the soil at a slow rate over a long period and localised wet areas will be present above ground.\n\nIf loss of containment occurs above ground through leaks or damage to pipework, due to the permeable stone around tank, sludge will also percolate into the soil at a slow rate over a long period.\n\nDue to operational presence on site, significant leaks (above or below) ground would be noticed and loss of containment would be mitigated through operational measures (closing of valves). \n\nTotal loss of containment is unlikely (partial loss of containment would be more likely to occur).",null,null,null,null,null,null,"1 in 100 to 1 in 1 Million","M"]
[null,"Vehicular impact (partial to catastrophic)","Impact from vehicles - damage to pipes or tank causing loss of containment","No known vehicle impacts - Bund exists around the tank\n\nHigh speed impact unlikely, but vehicle could damage pipework connected to tank (mixer pump) and cause a significant hole in the tank at low level. Could impact a potential weak point.",null,null,null,null,null,null,"< 1 in 1 Million","L"]
[null,"Vandalism","Vandalism of infrastructure - damage to pipes or tank causing loss of containment","No known vandalism to tanks or pipework.\n\nIf vandalism damage were to occur, total loss of containment is unlikely, but could occur if significant damage or on theft of mixer pumps and pipework. Partial loss of containment would be more likely to occur if slight damage was done.",null,null,null,null,null,null,"< 1 in 1 Million","L"]
[null,"Flooding","River flooding - Flood zone 2 and\nzone 3 - damage to pipes or tank causing loss of containment","The site is located adjacent to the River Anton to the west and south, and approximately 3.2 km from the River Test to the east. There are no recorded incidents of recent fluvial flood events at the site. The site is at very low risk of flooding from rivers or sea (<0.1% annual flood risk) and is located in flood zone 1.\n\n",null,null,null,null,null,null,"< 1 in 1 Million","L"]
[]
[null,"*Site is manned. Probability and frequency thus reduced"]
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[null,"Frequency of loss of containment (Ciria 736)","M"]
[]
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[1.4,"Overall zone hazard rating"]
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[null,"Overall zone hazard rating (Ciria 736)","High"]
[]
[]
[1.5,"Containment required"]
[]
[]
[null,"Containment required","Class 3"]

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[]
[]
[2.1,"Catastrophic/Partial failure - modes (loss of containment) "]
[]
[null,"The below proposed mitigation measures are recommended and should be read in conjunction with the proposed containment options in '5.Containment type-Total vol.' The risk rating after mitigation incorporates risk reduction due to the engineered containment options. Implementing the below measures will significantly reduce the probability and risk of failure from the tanks and significantly reduce the amount of secondary containment. As per CIRIA 736, the above will need to be implemented in conjunction with a good maintenance strategy as mentioned in Box 5.2,Page 60."]
[]
[null,"Risk","Cause","Existing consequence and mitigation measure",null,null,null,null,null,null,"Existing zone risk rating","Proposed Mitigation",null,null,null,null,null,null,null,null,null,"Risk rating after mitigation"]
[null,null,"Operational failure - tank (partial)",{"$f":"'1.Risk assessment'!$D$68","v":"Sludge is imported to the Site by tankers from approximately 30 sites on average by 5-6 29 m3 tankers daily. It is stored with the indigenous sludge in 2 No. sludge reception tanks before being pumped through 2 No. strain presses to 2 No. screened sludge storage tanks. In the event of overfilling/overflow or foaming conditions, the site is manned (7am – 5pm on weekdays, 7am – 1pm on Saturdays and 7am – 11am on Sundays) and so any loss of containment can be dealt with immediately and with tankers being on site within 2hrs, as part of an emergency response KPI with local tanker operator MTSR. Spills out of hours can be attended to within 1 hr.\n\nBoth clean and contaminated surface water is directed to a pumping station which recirculates it back into the system. The stormwater drainage of potentially contaminated areas from within the Site boundary is routed into the head of the works with no discharge outside of the site boundary. This allows site operations some time to deal with the leaks from operational failures. Flows exceeding the drainage system capacity will require mitigation with an improved inspection regime to catch spills prior to becoming significant."},null,null,null,null,null,null,{"$f":"'1.Risk assessment'!L68","v":"M"},"All tanks undergo a delegated inspection regime and the process parameters are monitored and understood by site operatives.\n\nSite operators are on site (7am – 5pm on weekdays, 7am – 1pm on Saturdays and 7am – 11am on Sundays). Daily site inspection regime will consist of a site walkover. Any defects located will be escalated to site manager for a repair resolution to be determined. If there is not an immediate risk posed by the defective asset and large scale repair is required then, the asset planning team will be informed in order to plan the necessary repairs. Any reactive works required will be undertaken by Site Operations team. \n\nInspection/Frequency\n>Walk round the site, identify and clear up any waste materials: Daily\n>Note signs of any deterioration of tanks or surroundings: Daily\n>Note any small leaks or spills, fix them and clean them up immediately: Daily\n>Integrity/Condition assessment all key sludge assets - Drain tank and inspect condition: 10 yearly\n\nFurther mitigation\n >A proactive planned preventative maintenance (PPM) and replacement programme linked to asset lifespan. Site Manager ensures the PPM is implemented effectively to minimise the probability of equipment malfunction. \n >A robust leak detection and repair plan will be set out and enacted\n >The site will be monitored using a telemetry to monitor tank levels and process flows. Trigger levels will be assigned to risk rating and proportional response will be taken. Alarms that protect against a loss of containment will have a response time the same as for other emergencies (Approx. 1 hr).\n>Penstock valves will be placed at strategic SW chambers to reduce the risk of sludge flows getting in to the SW drainage system. An automated solution for closing them and also any need for regrading of surfaces to reduce risk will be looked into at detailed design.\n\nControl of substances hazardous to health (COSHH) assessment undertaken for all raw materials.",null,null,null,null,null,null,null,null,null,"L"]
[null,null,"Structural failure - tank (catastrophic)",{"$f":"'1.Risk assessment'!$D$69","v":"The tank is primarily located above ground with some portion below ground. For any loss of containment below ground, the sludge liquid will percolate into the permeable soil at a slow rate over a long period if not detected by the level or temperature alarms.\n\nIn the case of significant damage above ground, the total volume contained above ground could spill. \n\nIn the event of a catastrophic failure, sludge would flow in all directions. The sludge would predominantly flow to the southern boundary. There is an existing natural ground slope along the road towards the southern boundary where the sludge will flow by gravity."},null,null,null,null,null,null,{"$f":"'1.Risk assessment'!L69","v":"M"},"The above inspection and further mitigation proposals will be applicable to structural failure, also.\n\nAs part of proposed mitigation, regular daily inspections of the site drainage systems and other equipment are to be undertaken, with any repairs and maintenance carried out if necessary.",null,null,null,null,null,null,null,null,null,"L"]
[null,null,"Structural failure - tank (partial)",{"$f":"'1.Risk assessment'!$D$70","v":"Partial structural failure of the tank would mainly be through surface defects.  In the case of significant defects forming above ground, the volume contained above ground would seep through the defects. If the defects are significant, the tank could potentially lose the above ground volume over a long period of time if the level and temperature alarms are not functioning. However, this is unlikely. \n\nDue to operational presence on site, large drops in levels in the tanks and significant leaks above ground would be noticed. Significant defects below/above ground would also be easily spotted during the daily visual inspections. \n"},null,null,null,null,null,null,{"$f":"'1.Risk assessment'!L70","v":"M"},"The inspection and further mitigation proposals outlined as mitigation for Operational failure will be applicable to structural tank failure, also.\n\nTo minimise loss of containment underground, it is advised that the tanks be visually inspected on daily basis and structurally inspected with increased regularity. Falling head tests should also be regularly carried out to limit any potential leaks underground. Tank to be refurbished if necessary.\n\nPermeable areas around the tanks (gravel) and low lying grassed areas are also to be replaced with impermeable hardstanding to remove the pathway to the ground. Soakaways to be filled in (concrete) and all connected drainage to connect to liquor return.",null,null,null,null,null,null,null,null,null,"L"]
[null,null,"Structural failure - pipework (catastrophic)",{"$f":"'1.Risk assessment'!$D$71","v":"In the unlikely event where the above ground rising mains to the tank, heatamix pipework or de-gritting pipework fails and breaks off, a significant volume would spill out. Tanks have level and temperature alarms and so any required valve could be immediately shut off by operational staff.\n\nThe consequence of a catastrophic failure of containment is it's able to flow in all directions. Based on topography, sludge will cascade towards the south and eventually into the drainage system.\n\nTotal loss of containment is unlikely. A partial loss of containment would be more likely to occur."},null,null,null,null,null,null,{"$f":"'1.Risk assessment'!L71","v":"M"},"To mitigate the very unlikely occurrence where the above ground pipework could fail/collapse, the necessary pump controls (Low and high pressure switches to trip the pump) need to be put in place, if not already, if there is a sudden loss of pressure in the rising mains (feed, mixing, hot water pumps rising mains), the pumps should stop. \n\nAll above ground pipework and chambers to be visually inspected daily. Structural inspections and falling head testing should be undertaken with increased regularity to test for any leaks. Pipework and chambers to be refurbished or replaced, if necessary to BAT standards. \n\nPermeable areas around the tank (gravel) and low lying grassed areas is also to be replaced with impermeable hardstanding to remove the pathway to the ground. Soakaways to be filled in (concrete) and all connected drainage to connect to liquor return.",null,null,null,null,null,null,null,null,null,"L"]
[null,null,"Structural failure - pipework (partial)",{"$f":"'1.Risk assessment'!$D$72","v":"Majority of pipework and connections are located above ground. Some of the pipework is located below ground or within the chambers below ground. \n\nIf loss of containment occurs underground (through leaks, joints and seals), sludge will percolate into the soil at a slow rate over a long period and localised wet areas will be present above ground.\n\nIf loss of containment occurs above ground through leaks or damage to pipework, due to the permeable stone around tank, sludge will also percolate into the soil at a slow rate over a long period.\n\nDue to operational presence on site, significant leaks (above or below) ground would be noticed and loss of containment would be mitigated through operational measures (closing of valves). \n\nTotal loss of containment is unlikely (partial loss of containment would be more likely to occur)."},null,null,null,null,null,null,{"$f":"'1.Risk assessment'!L72","v":"M"},"To assess the condition of underground pipework and chambers, CCTV and leakage detection (falling head tests) should be done on a regular basis to check if any leakage is experienced.  All above ground pipework and chambers to be visually inspected on daily basis for any leaks. Pipework and chambers to be refurbished or replaced, if necessary to BAT standards.\n\nPermeable areas around the tanks (gravel) and low lying grassed areas is also to be replaced with impermeable hardstanding to remove the pathway to the ground. Soakaways to be filled in (concrete) and all connected drainage to connect to liquor return.",null,null,null,null,null,null,null,null,null,"L"]
[null,null,"Vehicular impact (partial to catastrophic)",{"$f":"'1.Risk assessment'!$D$73","v":"No known vehicle impacts - Bund exists around the tank\n\nHigh speed impact unlikely, but vehicle could damage pipework connected to tank (mixer pump) and cause a significant hole in the tank at low level. Could impact a potential weak point."},null,null,null,null,null,null,{"$f":"'1.Risk assessment'!L73","v":"L"},"If the existing bund lacks the structural integirty, they are to be replaced with new vehicle barriers or bollards.Potential for the fence installed to be stronger and to be able to withstand some vehicular impact. The likelihood of such occurrence is low.\n\nThis is to mitigate any potential impacts from vehicles and potential damage which could lead to loss of containment. ",null,null,null,null,null,null,null,null,null,"L"]
[null,null,"Vandalism",{"$f":"'1.Risk assessment'!$D$74","v":"No known vandalism to tanks or pipework.\n\nIf vandalism damage were to occur, total loss of containment is unlikely, but could occur if significant damage or on theft of mixer pumps and pipework. Partial loss of containment would be more likely to occur if slight damage was done."},null,null,null,null,null,null,{"$f":"'1.Risk assessment'!L74","v":"L"},"Access to the site is restricted by manually operated gates which are open during operating hours.The Site perimeter is comprised of three quarters 10ft chainlink fencing with barbed wire and one quarter 3 wired barked wire fencing with trees. The site is manned during opening hours (7am – 5pm on weekdays, 7am – 1pm on Saturdays and 7am – 11am on Sundays), and staff are on call from Millbrook and Slowhill. The site only has CCTV monitoring the cess plant. \n\n[As per Main Supporting Document 790101_MSD_Main_FUL, Site Security, Page 30]",null,null,null,null,null,null,null,null,null,"L"]
[null,null,"Flooding",{"$f":"'1.Risk assessment'!$D$75","v":"The site is located adjacent to the River Anton to the west and south, and approximately 3.2 km from the River Test to the east. There are no recorded incidents of recent fluvial flood events at the site. The site is at very low risk of flooding from rivers or sea (<0.1% annual flood risk) and is located in flood zone 1.\n\n"},null,null,null,null,null,null,{"$f":"'1.Risk assessment'!L75","v":"L"},"Ensure flood plan for site follows EA guidance.\n\nInclude provision of sump pump to keep site clear of floodwater.\n\nEnsure diesel generators are at sufficient height to ensure they are not at risk of flooding (coastal or otherwise)",null,null,null,null,null,null,null,null,null,"L"]

{"sheet":"3.Containment volume-Total vol.","index":4,"n_rows":57,"n_cols":5,"rows_kept":57,"cut":false,"hidden":false,"merged":[[36,1,36,4],[5,1,5,4]]}
[]
[]
[3.1,"Secondary containment volume requirement - Inventory volume (above ground)"]
[]
[]
[null,"Due to the site layout and topography the containment solutions are provided through a number of bunds as outlined on worksheet 5. The calculation for each bund is shown below."]
[]
["Screened Sludge Tanks Bund"]
[null,"Tank Ref.","Total Tank Volume (m3)","Above ground Volume (m³)","Notes"]
[null,"Screened sludge storage tank 1",1000,750]
[null,"Screened sludge storage tank 2",1000,750]
[null,null,"Secondary containment volume of 110% of largest equals",{"$f":"D11*1.1","v":825.00000000000011},"m³"]
[]
["Sludge Reception Tanks Bund"]
[null,"Tank Ref.","Total Tank Volume (m3)","Above ground Volume (m³)","Notes"]
[null,"Sludge reception Tank 1",260,260]
[null,"Sludge reception Tank 2",260,260]
[null,null,"Secondary containment volume of 110% of largest equals",{"$f":"D17*1.1","v":286},"m³"]
[]
["Liquor Buffer tanks bund"]
[null,"Tank Ref.","Total Tank Volume (m3)","Above ground Volume (m³)","Notes"]
[null,"Liquor buffer tank 1",340,80]
[null,"Liquor buffer tank 2",340,80]
[null,"Liquor buffer tank 3",340,80]
[null,null,"Secondary containment volume of 110% of largest equals",{"$f":"D24*1.1","v":88},"m³"]
[]
["Polymer make up and storage"]
[null,"Tank Ref.","Total Tank Volume (m3)","Above ground Volume (m³)","Notes"]
[null,"Centrifuge Polymer storage & make up tank",2,2]
[null,"Drum Thickener Polymer storage & make up tank",2,2]
[null,null,"Secondary containment volume of 110% of largest equals",{"$f":"D30*1.1","v":2.2000000000000002},"m³"]
[null,"Each tank is to be considered individually as they are not co-located. Calculation illustrates containment required for each."]
[null,"Tanks are within bunded areas but detailed survey information is required to determine compliance to the required standards."]
[null,"Calculation provided to demonstrate/confirm the containment volume required for each."]
[]
[]
[null,"The following tanks are below the ground. As such no containment volume calculation to CIRIA C736 is specifically applicable.\nHowever this is not a do-nothing solution, impermeable surface and containment walls will be provided to mitigate the environmental risk from overtopping of the tank(s), see worksheet 5 for details.\nTank volumes and above ground volumes are provided for completeness."]
[]
["Digestors Bund"]
[null,"Tank Ref.","Total Tank Volume (m3)","Above ground Volume (m³)","Notes"]
[null,"Digestor 1",950,0]
[null,"Digestor 2",950,0]
[null,"Digestor 3",950,0]
[]
["Post Digestion storage tanks (PDST) Bund"]
[null,"Tank Ref.","Total Tank Volume (m3)","Above ground Volume (m³)","Notes"]
[null,"Post digestion storage tank 1",287,0]
[null,"Post digestion storage tank 2",287,0]
[]
["Centrifuge liquor buffer bund"]
[null,"Tank Ref.","Total Tank Volume (m3)","Above ground Volume (m³)","Notes"]
[null,"Centrifuge liquor buffer tank 1",115,0]
[null,"Centrifuge liquor buffer tank 2",{"$f":"C52","v":115},0]
[]
["Thickened sludge storage tank"]
[null,"Tank Ref.","Total Tank Volume (m3)","Above ground Volume (m³)","Notes"]
[null,"Thickened sludge storage tank",260,0]

{"sheet":"4.Current asset evaluation","index":5,"n_rows":26,"n_cols":3,"rows_kept":26,"cut":false,"hidden":false,"merged":[]}
[]
[]
[null,"Sludge reception tank selected as representative of wider site conditions"]
[]
[4.0999999999999996,"Current Asset Evaluation","Sludge Reception tank 01"]
[null,"Description","Approximately 780 m3 of sludge is imported to the Site by tankers from approximately 30 sites on average by 5-6 29 m3 tankers daily. It is stored with the indigenous sludge in 2 No. sludge reception tanks before being pumped through 2 No. strain presses to 2 No. screened sludge storage tanks."]
[null,"Number of tanks","1 (Risk assessed for one tank only)"]
[null,"Volume of tank","265 m3 (approximately) - total volume for tank"]
[null,"Material of tank","Steel"]
[null,"Above/below ground?","Above ground tank with some portion below ground"]
[null,"Pipe material","All connecting pipework is thick-walled – some above ground and some below ground."]
[null,"Drainage for zone","The drainage is directed towards the Eastern direction\n\n[As per Fullerton WTW Drainage, 720116/M104/1403]"]
[null,"Year of construction","-"]
[null,"Surrounding area","Gravel"]
[]
[null,"Pump rate - to Sludge Reception tank 01","-"]
[null,"Pump rate - from  Sludge Reception tank 01","-"]
[]
[]
[null,"Is asset fit for purpose?","The tanks were originally designed and constructed to hold sludge and has been operating with no notable concerns.  \n\nTank has not undergone a change of use"]
[null,"Condition of the tank\n\nAny tank failures - cracks, flaking, corrosion, overflows, overfilling?","no structural concern"]
[null,"Condition of pipework\n\nPipe leaks, corrosion?","No visible issues/leaks reported by operational staff"]
[null,"Protection of assets ","The existing bund needs to be tested for integrity. If found defective, new vehicular protection/bollards needs to be provided."]
[null,"Control/monitoring/alarming measures in place?","All tanks undergo a delegated inspection regime and the process parameters are monitored and understood by site operatives"]
[null,"Secondary containment provided?","Bund exists around the tank"]
[null,"Secondary containment condition?","-"]

{"sheet":"5.Containment type-Total vol.","index":6,"n_rows":205,"n_cols":13,"rows_kept":205,"cut":false,"hidden":false,"merged":[[134,1,134,10],[135,1,135,10],[136,1,136,10],[127,1,127,10],[128,1,128,10],[129,1,129,10],[130,1,130,10],[131,1,131,10],[98,1,98,10],[147,1,147,10],[148,1,148,10],[149,1,149,10],[142,1,142,10],[143,1,143,10],[144,1,144,10],[145,1,145,10],[146,1,146,10],[104,1,104,10],[105,1,105,10],[139,1,139,10],[140,1,140,10],[141,1,141,10],[132,1,132,10],[133,1,133,10],[118,1,118,10],[119,1,119,10],[120,1,120,10],[121,1,121,10],[126,1,126,10],[122,1,122,10],[4,1,5,10],[93,1,93,10],[94,1,94,10],[96,1,96,10],[153,1,153,10],[106,1,106,10],[111,1,111,10],[108,1,108,10],[109,1,109,10],[110,1,110,10],[112,1,112,10],[113,1,113,10],[117,1,117,10],[115,1,115,10],[116,1,116,10],[107,1,107,10],[159,1,159,10],[160,1,160,10],[161,1,161,10],[162,1,162,10],[59,12,60,12],[114,1,114,10],[97,1,97,10],[100,1,100,10],[95,1,95,10],[152,1,152,10],[99,1,99,10],[102,1,102,10],[101,1,101,10],[103,1,103,10],[123,1,123,10],[124,1,124,10],[154,1,154,10],[155,1,155,10],[156,1,156,10],[157,1,157,10],[158,1,158,10],[192,2,192,10],[193,2,193,10],[194,2,194,10],[195,2,195,10],[163,1,163,10],[164,1,164,10],[165,1,165,10],[166,1,166,10],[167,1,167,10],[168,1,168,10],[169,1,169,10],[170,1,170,10],[171,1,171,10],[172,1,172,10],[173,1,173,10],[174,1,174,10],[190,1,190,10],[191,1,191,10],[201,1,201,10],[202,1,202,10],[203,1,203,10],[209,1,209,10],[204,1,204,10],[205,1,205,10],[206,1,206,10],[207,1,207,10],[208,1,208,10],[196,1,196,10],[197,1,197,10],[198,1,198,10],[199,1,199,10],[200,1,200,10]]}
[]
[]
[5.0999999999999996,"Containment to be provided"]
[]
[null,"Based on a 'High' site risk rating for the zone, all tertiary options in Section 5.4 are based on Class 3 containment which includes impermeable lining to protect soil and groundwater infiltration."]
[]
[]
[null,null,null,null,null,null,null,null,null,null,null,null,"Typical Bund section view"]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[null,null,null,null,null,null,null,null,null,null,null,null,"Typical reinforced concrete wall section view"]
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[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
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[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[5.3,"Site overview"]
[null,"Overview of whole site",null,null,null,null,null,null,null,null,"Main STC area"]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[null,null,null,null,null,null,null,null,null,"See 790101_MSD_SiteLayoutPlan_FUL for more detail of asset type/location "]
[]
[]
[5.4,"Containment Solutions"]
[]
[null,"Due to the site topography with respect to the location of the relevant tanks the solution for this site is a number of smaller discreet bunds as outlined below. "]
[null,"In this scenario the '110% rule' applies for each bund, see worksheet 3 for calculations. Above-ground volumes are used in line with CIRIA C736 and reflecting a practical spill scenario."]
[null,"New impermeable surfaces will be provided to existing gravel and grass areas as required to provide an appropriate bund floor."]
[]
[]
[]
[null,"Sludge Reception Tanks"]
[null,"The sludge import tanks are within a small concreted area with small wall but this does not meet CIRIA requirements. \nA bund extension will be constructed to provide the required containment of 110% of one tank. This area is broadly level and there is sufficient space to provide a containment solution utilising new walls and new impermeable surface.\nThe specific final shape of this bund remains subject to surveys, an illustrative shape and size is provided to the right.\nSome local re-grading for drainage falls will be completed and impermeable membrane installed. Walls will be constructed to provide the required containment volume."]
[]
[]
[]
[null,"Screened Sludge Tanks Bund"]
[null,"The screened sludge tanks are partially buried but have above ground volume that requires a new containment solution.\nThese will be provided with a new bund to contain 110% of the above ground volume (see worksheet 3).\nNew concrete bund walls are required and new impermeable surface will be installed within the bund. \nThe unusual shape of the bund (illustrated to the right) looks to minimise the wall height within the site constraints whilst providing the required containment volume.\nThe area is constrained by roads (which are required to remain for access and emergency response) and land ownership extent.\nThis bund cannot be combined with digestor bund due to existing topography of a significant ground level difference. \nThe uncommon shape remains subject to constructability review in destailed structural design wherby the contained volume will maintained and determine the final wall height. Some re-grading of the area to provide a more level surface (but including drainage falls) will provide some additional capacity but walls are anticipated to be around 1.5m tall."]
[]
[]
[]
[]
[]
[null,"Liquor Buffer tanks bund"]
[null,"The liquor buffer tanks are used for liquor storage prior to return to the WtW.\nThe tanks are largely buried but a proprtion is above ground (see worksheet 3 for containment calculation).\nContainment will be provided by way of allowing a spill to spread across the area illustrated to the right. Examination and remediation of existing hardstanding is required, and some new impermeable areas are required to extend the area.\nA short wall will be installed around the perimeter, on the southern end where vehicle acces is required a speed hump will be used."]
[null,"A steep slope to the north of the bund illustrated restricts the practicality of using this area. "]
[]
[]
[]
[null,"Polymer make up and storage"]
[null,"Two polymer make up (mixing bagged poly with water) and storage (day tank) facilites are used on site. \nThese are for the centrifuge and drum thickeners and are located within the respective buildings.\nThis is a propriety system whereby a vertical tank is split vertically into two halves, the top half for mixing polymer which then passes usable product to the bottom half for draw off for process use (illustrated to the right wherby the tanks are on the right). The full volume has been used for containment calculations (on worksheet 3).\nThey are within an exisiting bunded area with concrete floors however the containment calculation has not yet been verified to CIRIA requirements. The bund walls will be increased in height to provide the required containment volume. Drainage solutions will be amended where required to ensure appropriate solution and operational control (these are indoor so no rainfall expected in the bunds).\nThe liquor buffer tanks solution (above) will provide adequate containment for the drum thickener poly unit, however for operational safety it is prefereable to restrict the spread of polymer to a much smaller area.\n"]
[]
[]
[]
[]
[null,"Solutions for the below-ground tanks are outlined below."]
[]
[null,"Digestors Bund"]
[null,"The digestors are buried with only the tank roof being visible above ground. As such there is no related above ground storage volume against which to undertake CIRIA C736 containment calculations. The risk over overfill of the tank is minimised through the use of insrumentation and controls, however in recognition of EA guidance, improvements to the surrounding impermeable area will be undertaken and a small wall created around the perimeter to contain any potential over topping of the tanks. The tanks are adjacent to a step embankment, detailed survey os required to confirm the location but is to be at teh extent of teh existing hardstanding and is planed to be ~300mm tall."]
[null,"The concrete digestors are buried and have level monitoring but we acknowledge the guidance provided regarding the need for containment on the basis of risk of overfilling in this scenario. These are in an area that has existing, largely level, hardstanding surface between the tanks with slopes on the external sides.\nA survey of the existing impermeable surface will be completed and remedial works undertaken to provide containment up to a new 300mm concrete bund wall installed to contain any spills. The approximate extent of the bund wall is illustrated below (red lines) and remains subject detailed survey and detailed design solutions as the position is sensitive to local topographic variations.\nThis approach will be supported by tank integrity inspections to a revised written scheme of examination in line with BAT requirements."]
[]
[]
[null,"Post Digestion storage tanks (PDST)"]
[null,"The PDSTs are similarly buried and have level detection, these will be provided with new walls of 600mm height and new impermeable surface (yellow shading).\nAn alternative solution that utilises some existing adjacent hardstanding areas and kerbs would allow a large spill to spread around the buildings and concrete areas shown in the image below (detail of remediation remains subject to survey). This requires further survey to ensure the operational impacts are understood and will be reviewed in detailed design as it is likely to offer a more cost effective solution.\nThis bund cannot be combined with the digestors due to existing topography and significant height difference."]
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[]
[]
[]
[]
[]
[]
[]
[null,"Centrifuge liquor buffer bund"]
[null,"The centrifuge liquor buffer tanks are underground cylindrical concrete tanks that provide buffer storage capacity, specifically for the liquor from the centrifuges. No specific CIRIA C736 calacultion applies but in recognition of the risk of level detection devices failing and overtopping the tanks a new impermeable surface and a short wall of ~300mm will be installed."]
[null,"Note: These cannot be combined with the PDST bund due to existing topography (these tanks being significantly lower)."]
[]
[]
[]
[null,"Thickened sludge storage tank"]
[null,"The thickened sludge storage tank forms part of the drum thickener building structure, it is an underground rectangular concrete tank.\nNo specific CIRIA C736 calacultion applies but in recognition of the risk of level detection devices failing and overtopping the tanks a new kerb will be installed around the existing concrete surface to contain any spillages. The required drainage improvements to co-ordinate this wil general surface drainage will be completed."]
[null,"Note: the tank shown in the top of this image is not used/out of service so does not form part of containment calculations. "]
[]
[]
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[]
[null,"The solution outlined is in line with planned scope, however design solutions are subject ot ongoing survey outcomes and detailed evaluation of a number of emerging operational considerations to determination the overall most appropriate solution for a given bund. \nFurther design may determine the need for additoinal features which may include measures to ensure teh exclusion of buidlings in spill areas, lagoons or altered bund boundary lines."]
[null,"The wall type remains subject to confirmation following further detailed design development and contractor input. \nThe current preferred solution is for new earth bank with concrete canvas liner where space allows, and concrete walls where space is constrained.\nAdditional wall types are available and form part of the ongoing design development considerations to ensure the most appropriate solution is adopted. These are typically formed of a structural wall element (pre-formed concrete blocks, sheet piles, gabion cages) with a liner. Until the full review has been completed and appropriate competent person has signed them off this remains subject to context-specific evaluation."]
[null,"New impermeable surfaces meeting the required 10^-9m/s impermeability will be installed in line with CIRIA C736. \nThis is planned to be primarily concrete canvas but some localised area may require reinforced concrete or be more suited to alternative solutions from table 8.2 of CIRIA C736.\nNew impermeable areas will provide a continuous surface over the area identified as within the bund, this includes existing grass or gravel areas between tanks and equipment. Details for tie in to existing structures to ensure an appropriate containment solution will either be to manufacturers details or developed on specifically for the application.\nSome existing surfaces will be utilised, the extent remains subject to detailed survey and identification of appropriate remediation to ensure it meets an appropriate standard."]
[null,"In the event of a spill the contained sludge and any rainwater will not be returned to the works inlet. It is proposed that sludge tankers will be utilised to empty the bund with suction hoses. This will form part of revised spill procedure based on the final design and further assessment and planning.\nThe scope includes new sumps, electrical pumps, sample points and the required pipework to return the rainwater to the works inlet. The location of sumps and pipework routes will be identified in detailed design. \nThe rainfall containment volume accounts for 24hours at AEL rainfall. Noting the CIRIA C736 requirement for 8 days at AEL, further design and operational planning will determine the detail of a recovery scenario (re. tanker removal vs rainfall accumulation), the outcome of this will inform the final allowance for freeboard for rain and the findings will be reflected in the final wall heights."]
[null,"CIRIA C736 requires rainfall allowance in capacity calculations for 10% AEP rainfall for; 24 hours [prior to the incident], the duration of the incident, eight days [after the incident] (or other period appropriate to the particular site circumstances).\nThe final wall heights will include for appropriate freeboard and rainwater containment volumes based on the completion of design and calculations.\nA rainwater allowance of up to 136mm in line with a worst-case region 3 rainfall for 24 hours plus 8 days will be applied to the final wall height. \nThe solutions shall remain 'as drawn' but the wall height will vary to accommodate the final calculation.\n"]
[null,"Additionally a firefighting foam allowance of >100mm is required if the contents are combustible. These products are not combustible so this allowance does not need to be applied.\nSurge allowance of 250/750mm is recommended in line with CIRIA C736 table 6.3.\nThe final confirmed height of walls including freeboard allowance remains subject to detailed design and final calculations.\nNo bunds are covered so rainfall is relevant.\nAn operator action for starting the bund drain pumps daily as required aligns to the 24 hours pre-incident requirement.\nThe duration of the event depends on the severity (partial failure/catastrophic) but it is considered feasible to utilise road tankers (for holding) to empty bunds at any given point. These are used widely by the company. The CIRIA C736 allowance for 8 days post incident rainwater capacity is considered in relation to the ability to manage water levels post-incident. In this scenario it is considered feasible to remove the spill from the bund and into tankers in the event of significant rain."]
[null,"The allowance for post incident rainwater is anticipated to be related to particular site circumstances as CIRIA C736 allows.\nThis requires completion of the design and [it is anticipated] this will be part of further discussion(s) with local EA officers to gain agreement.\nFurther design and operational planning will determine the detail of a recovery scenario (i.e.. calculations for tanker attendance time, pump rate for removal vs rainfall accumulation), the outcome of this will inform the final allowance for freeboard for rain and the findings will be reflected in the final wall heights.\n"]
[null,"No allowance for firefighting foam capacity has been made as the substances under consideration are not flammable.  As such, fire is not a scenario that is considered practically feasible and is considered to align to CIRIA C736 figure 4.3 for non-combustible contents\nThis remains subject to acceptance by the Environment Agency in design development and acceptance of improvement condition plans. Should it be deemed required an allowance can be made on wall heights to accommodate this."]
[null,"Overfilling tanks has not been modelled as the operational control processes (level gauges, SCADA etc) are thought to be sufficiently robust to demonstrate this spill scenario requires less containment than a catastrophic tank failure scenario. Additionally the tank modelled is the largest tank and tank transfers are only completed from single tank to single tank. Surveys in relation to level gauges etc to address BAT 19 and subsequent analysis of findings will determine if this correct."]
[null,"Surge allowance will be made on a standardised basis of additional height on the bund wall."]
[null,"The use of flood gates has been excluded from the solution on the basis their operation is not guaranteed to be timed correctly, presents a single point of failure and may adversely impede any response scenario."]
[null,"The distance of tanks from walls means jetting to outside of the bunded area is unlikely, this remains subject to further evaluation and calculation in the next stage of design including consideration of tank types and the orientation (e.g. concrete tanks, other buildings/existing fences etc). Should a jetting risk be determined appropriate mitigating measures will be implemented as part of the overall solution to ensure any liquids remain within the bunded area."]
[null,"New sumps and pumps will be located to accommodate the drainage falls."]
[null,"The drainage solution for the area will be reviewed and further intrusive surveys completed to ensure any existing drainage that may be utilised is of good condition and retains water in line with the bunding requirements. It is anticipated that extensive drainage modifications will be required to ensure all bunded areas are captured and surface water dealt with in line with BAT. This requires additional design work to determine the most appropriate solution.\nAny existing soak aways (or similar) within a bunded area will be removed and appropriate BAT compliant drainage solutions provided.\nThis includes provision of a means of isolation of the existing drainage from returning to the WtW/head of works in the event of a spillage.\nRoof areas where BAT permits for uncontaminated rainwater to be directed to the ground (outside the bund) will be considered to reduce the amount of water flowing in drains or returned to the WtW."]
[null,"Existing pits, chambers and other existing assets in the bunded area will be reviewed on a local basis to determine the most appropriate solution to provide appropriate containment.\nThis is anticipated to require the replacement of pit covers with water tight/sealed versions to ensure containment. This is not reflected in CIRIA C736 but is considered appropriate and the wholesale removal of pit and ducts, underground chambers and pipework is cost-prohibitive."]
[null,"No retrofitted leak detection under existing tanks is proposed, alternative solutions to manage the risk will be developed. This will include tank inspections, tank periodic hydrotesting and (subject to contamination hydrogeologist review of the application) boreholes to monitor for leakage.\nThe basis for this is that retrofitting may cause settlement issues or create voids under tanks which would counter the objective of the leak detection. Additionally most tanks have either a concrete tank base, or a concrete foundation under the tank base, thus providing an appropriate impermeable surface in line with CIRIA C736."]
[null,"All pipework would be within the bund and thus provided with appropriate containment. Existing underground pipework would not be replaced wholesale but will be tested/inspected and appropriate solutions developed based on the findings. \nOver time the underground pipework would be replaced with above-ground pipework as and when other projects require changes to the site layout/operation. Where pipework is not within the bunded area a case by case review will determine an appropriate means of leak detection and secondary containment (based on factors like insulation, condition, routing, pumped/gravity system)."]
[null,"This solution incorporates all process areas, thus a failure of equipment within the process area would be appropriately contained within the bunded area."]
[null,"Existing walls and kerbs will be utilised for spill areas, these will undergo a detailed survey to identify appropriate remediation which will be completed to provide an appropriate containment 'wall'. Speed humps will be installed on the roads to reduce the spread of any smaller spills."]
[null,"Spill modelling has not been completed for all tanks as CIRIA C736 does not require this, nor is it thought required as part of normal good practice. The containment of all tanks and the suitability of the design for this scenario has been assured through consideration of existing topo and consideration of the flows in a given area relative to the volume of the tanks in consideration."]
[null,"Provisional DSEAR guidance suggests any methane present would disperse rapidly and not present a potentially explosive atmosphere. Further evaluation of this will be undertaken in design and may determine the need for design changes which would be incorporated to the solution outlined."]
[]
[null,"Modelling notes."]
[null,"The model was built in Infoworks ICM 2021.9 and provides a 2D output of a 3D scenario"]
[null,"The model utilised a combination of LiDAR / Digital Terrain Model data with topographical survey data as an additional reference"]
[null,"A mesh was created by the modeller to represent the topography of the existing site"]
[null,"Drainage was excluded on the basis that modification of drainage systems will be required to ensure no links to outside the bund."]
[null,"Building areas were excluded from containment volume areas - assumes no flooding of internal areas of the building"]
[null,"The whole area is treated as impermeable surface reflecting the required final state for the bund floor"]
[null,"Levels and wall heights represent 'settled' levels"]
[null,"Rainfall has been accounted for in the model scenarios - however this will be verified in relation to final wall heights (see design development)"]
[]
[]
[null,"Solution Development Notes with respect to the wider context within which IED will be delivered"]
[]
[null,"The design for the containment continues to progress and remains subject to further development."]
[null,"The design will require sign off by a competent civil or structural engineer."]
[null,"CIRIA C736 compliance is the objective (and BAT is the referenced requirement). \nA few elements regarding CIRIA C736 details in the context of this application will be reviewed by a qualified engineer for suitability and as outlined in CIRIA C736 we will look to discuss this with the EA as our regulator. \nSome queries are in line with additional guidance offered by the Agency in other forums (TaF, Defra meetings et. al.).\nThis may include:\n\n\n\n\n\n\n"]
[null,"Accounting for rainfall accumulation in bunds will be reviewed in further detail to determine final wall heights - this will look to consider:"]
[null,null,"Operational process in no-spill scenario for daily removal of rainwater and return to head of works (inc. determining the presence of spilled sludge)"]
[null,null,"Emergency response in spill scenario for removal of sludge (likely using road tankers and suction)"]
[null,null,"Allowance for climate change in rainfall calculations"]
[null,null,"Duration of AEL rainfall required to be accommodated with respect to CIRIA C736 and the final operational basis for normal and spill scenarios"]
[null,"Steel plating over joints as the origin of this (within CIRIA C736) was in related to a fire scenario for hydrocarbon storage and may not be required for STC/sludge facility/storage."]
[null,"The relationship between the risk assessment 'CIRIA classification' and the details for the solutions proposed, particularly differentiating between Class two and class three requirements."]
[null,"The use of Concrete Canvas (as it is not listed in CIRIA C736 table 8.2 but can be demonstrated to meet the 10^-9m/s impermeability requirement)"]
[null,"The need for sub-surface 1m impermeable soil based on type of stored material (re. CIRIA C736 figure 8.4) and the requirement for under-bund lead detection (class 3). An alternative solution with lower carbon impact may be proposed for the sub-surface and based on SMR in-situ remediation solution. "]
[null,"Where existing surfaces are proposed to be utilised the details in CIRIA C736 may not be fully achieved as retrofitting of water bars is not considered feasible. A suitably qualified person will be required to approve any proposed solutions."]
[null,"The use of sealed covers for existing pits as not clearly defined in CIRIA C736 but considered to be an effective and realistic solution"]
[null,"The context in which IED will be delivered at this site will look to reflect the wider guidance provided around IED implementation."]
[null,"The following points are considered relevant factors in provision of the final solution implemented at the site:"]
[null,"Wording of improvement conditions and agreement for acceptable solutions with Local Agency Installation Officers only being possible upon receipt of permit/draft permit"]

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