Road Gully Cleansing
Perth and Kinross Council · 28 August 2024
Back to Economy and Infrastructure Committee — 28 August 2024 and its agenda
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Perth And Kinross Council Economic and Infrastructure Committee 28 August 2024 ROAD GULLY CLEANSING Strategic Lead - Environment and Infrastructure (Report No. 24/233) 1. PURPOSE 1.1 Remit from Environment, Infrastructure & Economic Development Committee of 1 November 2023 to report on progress and performance on gully cleansing over the last few years. 1.2 This report will cover the gully function/disposal mechanism/cleansing/ capacity/performance and costs. It will further detail issues and barriers to achieving targets. 2. RECOMMENDATIONS 2.1 It is recommended that Committee: - (i) Note the content of this paper in relation to the gully cleansing activity performance, the actual purpose of a road gully, how it operates and its limitations in mitigating flooding occurring. (ii) Note no enhancement to the activity is recommended by officers but if any enhancement is required, then additional labour and financial resource will be required to achieve it. 3. STRUCTURE OF REPORT 3.1 This report is structured over the following sections: Section 4: Background/Main Issues Section 5: Proposals Section 6: Conclusion Appendices 4. BACKGROUND / MAIN ISSUES 4.1 There are 46,610 road gullies across the Councils 2481km of public road network. This number increases annually as new residential and commercial developments are adopted and gullies are found on the existing network and added to the asset register.
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4.2 Gullies are designed to collect rainfall which falls onto the public road and store that water to allow particulates to settle and separate out so reduced amounts are conveyed into the pipe/watercourse network. 4.3 Gullies are not designed as storage for floodwater with each modern pot having an approximate 90 litre/20gallon capacity. Their spacing is determined by the road surface area being drained and they are not designed to take water from surrounding land. 4.4 Gully cleansing aims to remove the particulates that have settled in the gully pot, not to remove water. 4.5 Most gullies are what we describe as ‘trapped’ and sit with water in them similar to a toilet, to prevent odours coming back out of the pipework. See Figure 1 below for general detail of a road gully. Figure 1 4.6 Gullies drain in a variety of ways: into the public sewer system (which is managed and maintained by Scottish Water) into a piped system managed and maintained by the Council that then discharges into a burn/watercourse/sewer into a roadside ditch – which is there to take road water not drainage from adjacent land into a soakaway, a stone filled receptacle or buried stone pile, that naturally percolates into ground, and is maintained by the Council (unless it is in private land) directly onto the surface of a verge/adjacent land and then just percolates into the ground. 4.7 Scottish Water do not typically permit new gullies to be connected into the sewerage system due to capacity issues and through National Planning
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Framework 4 – Policy 22(c)(ii) has a presumption against surface water connections to combined sewers. SEPA must be consulted on any proposal to discharge any new gullies to a watercourse/burn to determine any mitigation measures required to prevent pollution entering the natural environment. 4.8 Further, NPF4 – Policy 22(c)(i) states that ‘Development proposals will: not increase the risk of surface water flooding to others, or itself be at risk.’ In simple terms, a neutral or better approach is required. Specific details on acceptable designs of surface water management systems can be found in the PKC ‘Flood Risk and Flood Risk Assessments’ document (adopted March 2021)1. This includes information about the scale of rainfall event that is allowed to enable the system to surcharge, the scale of rainfall event that is allowed to enable the system to flood, and what the developers should do to manage the overland flows once the system is flooding. 4.9 Roadside drainage ditches, and those on private land, can be maintained without seeking permission from SEPA but excavated material must be disposed of appropriately due to the ‘contaminated’ nature of hydrocarbons and grits that are washed off road surfaces. 4.10 Gullies may often appear blocked in heavy downpours because the water is lying on the road surface. This can happen for a number of reasons: the capacity of the pipe system is exceeded (they are designed to take a certain amount of water), the rate at which water arrives at gullies is beyond what the gully can accept (so the water ‘skips’ over the top), or the gully is blinded by leaf litter / debris / silt (typically washed off hard surfaces and fills the gully pot). 4.11 Gullies are generally only blocked, and requiring a visit from the gully machine when the rain has stopped and capacity has returned to the system but the standing water does not drain away from the road surface. 4.12 Weed growth in the gully frame is not necessarily an indication that the gully is blocked, nor indeed that it has missed a gully cleanse allowing the weeds to grow. 4.13 Tayside Contracts (TC) carry out the gully cleansing operation across the public road network utilising 4 machines based in Perth (2), Blairgowrie and Aberfeldy. 4.14 The gully operative forces clean water into the pot to dislodge the sludge and sucks out the dirty sludge until such time as the pot is clear. They then rinse and flush the pot and outlet pipe. 4.15 Gully waste is deposited at a reed bed facility near Almondbank where the water naturally cleanses as it drains through the reed beds, leaving the solids to be uplifted and taken to approved landfill. 4.16 Gully machine operators are directed on a day to day basis by the local Assistant Road Maintenance Officer (ARMO). 1 PKC - Flood Risk and Flood Risk Assessments: https://tinyurl.com/PKC-FRA
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4.17 Gully cleansing is recorded, in real time, on a tablet and since 2023/24 data is stored within the Road Asset Management system (RMS). 4.18 In early 2000’s all gullies were cleansed annually however this was considered unaffordable and unnecessary as not all gullies required this frequency. 4.19 In 2015 an exercise using commercial software was undertaken to gather information about gully location, type, and condition on arrival. It was intended this data would enable a more targeted approach to cleanse only those that showed up as exceeding 50% blocked on arrival. 4.20 The project had limited success for a number of reasons: Period of time taken to gather the data and establish trends No real pattern obvious around why and when a gully would fill with debris Apparent requirement for example to cleanse 3 in a street and leave other 36 yet need to return short period later to ones not cleansed Fielding complaints about not cleaning all gullies whilst in one location Time taken to travel between settlements/streets exceeding time taken actually cleansing gullies Time taken “physically digging” gullies out due to debris build up over longer period Issues opening covers to access the gully pot as it had been left so long – with many requiring frame/cover removal and replacement System required manual interrogation to establish outputs, which could be extracted by gully motor and month but not by ward as detailed in Appendix 1 4.21 As targeted cleansing was not effective and global annual cleansing not achievable, the following operational regime was implemented in 2019: A Class roads – annual cleanse Linear and channel drains – annual cleanse Flood susceptible – annual cleanse Manholes – every three years Chokes (gullies / manholes, linear etc) and observed high silt levels – as known 100% clean by ward – Biennially 4.22 Blocked gullies are routinely picked up by Assistant Roads Maintenance Officer (ARMO) and a cleanse arranged and reports are also received via MyPKC of blocked gullies. Many of these reports are not blocked however it is not possible for the ARMO to respond to every notification. ARMO will continue to monitor and arrange cleanses as required without contacting the notifier. 4.23 In order to maximise outputs, each ARMO directs the gully machine operator to a location to cleanse all gullies Monday to Thursday. Each gully takes a
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variable time to cleanse due to levels of siltation, but by cleansing in a specific location (village/settlement/area) daily travel time is minimised and output maximised. Fridays are used to attend to reported/observed blocked gullies, again trying to target by location albeit this is not so efficient due to the disparate nature of blockages. 4.24 Historic performance numbers for cleansing gullies is as follows: - 2018/19 2019/20 2020/21 (* figures from 1 July 2020 only) 2021/22 2022/23 2023/24 22,308 22103 *20,777 22,675 #18,922 22,208 # recording system down for several months requiring manual records to be kept 4.25 Flood susceptible areas have been identified and are included on an annual cleanse. These can be on the A Class network and so would be cleansed anyway but are often on other classes of road. Not everywhere that has experienced flooding is included but those that are: Alyth Rattray Pitlochry (nr Co-Op) Cargill Feus Rd Marshall Pl Bridgend Queens St/Windsor Terrace Back St / Burnbank / Earnbank in Br of Earn Invergowrie (specific streets) Milnathort 4.26 Since April 2023 a cleansing monitor is available and outputs can be measured by month (each gully cleanse is date/timestamped) across wards. Appendix 2 details outputs across all wards for financial year 2023/24 and to end July 2024, and this will enable yearly comparisons moving forward. As can be seen outputs during winter are lower as the water in the gully motor freezes, resulting in the machine operating less efficiently. Additionally, flood events considerably reduce outputs as the gully machines are directed to reactively deal with blockages which increases travelling (non-productive) time. 4.27 A visual interrogation of the system also details gully location and cleansing history. It is intended this be made publicly available when sufficient data is held and when technically feasible/resources permit. Appendix 3 is an extract from ward 11 with cleansing history shown.
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4.28 Ditch clearing was, until the early 2000’s, carried out on an approximate 10- year cycle. Reductions in budget and staffing resource has resulted in no proactive ditch clearing taking place and limited reactive cleaning since 2008, with only problem locations cleared when resources are available. This prevents water discharging from gullies and channels cut through the verge (offlets) from getting into the ditch and draining away. 4.29 The RMP maintain some piped systems, mainly in the rural / village / settlement contexts. These are not jetted or cleansed and are only attended to if the system ceases to function as intended. This can be caused by a blockage in the pipe or at the outlet from the pipe and these localised issues will receive attention to get the system operational again. Other piped systems are generally managed and maintained by Scottish Water and the Council is not responsible / funded / resourced for any aspect of maintenance of this asset. Pipes / culverts / drains and watercourses that run through private land, that carry surface water are the responsibility of the property / landowner to maintain; this is the principle of ‘riparian ownership’2. Where this falls to private property owners, it is not always known to them that they have certain responsibilities. The Council will assist by way of providing advice in these situations where possible but are typically unable to act on private ground. 4.30 Typically, combined sewer and foul sewer systems are ‘adopted’ by Scottish Water, and the maintenance of them is their responsibility. Some surface water sewers are adopted by Scottish Water, but others are either the responsibility of the landowner(s) or Perth and Kinross Council. This latter aspect often involves a degree of research to identify the owner prior to undertaking any works. 4.31 The Council area was previously split into 12 geographic areas each with a Roads supervisor and 4 Road Superintendents managing them. From 2008 this has reduced to 2 Superintendents (now Road Maintenance Officers) and 7 supervisors (now ARMO). With the increased size of area for each ARMO and increased workload, the opportunity to engage proactively and build up relationships with adjacent landowners has been reduced. 4.32 Over the past few decades reduced manpower and increasing size of agricultural vehicles has meant farmers have changed away from contour ploughing / against the slope, which created furrows running counter to the slope (which reduced the flow of water/soil downhill). Much of the ploughing is now counter contour / with the slope of the land and results in water cascading down the furrows and straight onto the neighbouring land (road / gardens / properties), along with soil/stones/crops etc. 2 Scottish Government – Clearance and Repair to Reduce Flood Risk: Local Authority Guidance: https://tinyurl.com/SG-LAG
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4.33 Landowner discussions have been restarted in neighbouring Council areas, between them and the Council itself. The same approach is needed in Perth and Kinross, to re-engage and restate responsibilities of landowners that border private developments to minimise the impacts of runoff of water and other material. It is acknowledged that the ‘Higher Owner’ is not legally obliged to provide defence to the ‘Lower Owner’ by undertaking specific works in this regard, however, it could be argued that by working the land, the landowners may be considered to have ‘overstretched’ their rights and have altered the route of natural drainage in the area3. The Council have no remit to ‘force’ landowner to adjust their practices (unless specific conditions are met per the Flood Risk Management (Scotland) Act 2009), so are reliant on understanding and informal agreements between all parties. 4.34 Other agencies involved here include SEPA and Scottish Water. The former is the ‘warn and inform agency’ with regards to provision of flood alerts and warnings for members of the public and the Council. SEPA is not permitted to undertake any works to mitigate flooding impacts as they happen, but they are a statutory consultee in the Planning process and provide comment on flooding and surface water management. 4.35 Scottish Water are responsible for provision of potable water, and more pertinently maintaining (many) sewerage systems. It is a common misunderstanding that drainage systems (adopted by Scottish Water) must take all water landing on it. In line with the Council guidance1 (derived from Scottish Water’s Sewers for Scotland – v4 document4), surface water drainage systems are designed to accept the 1:30yr magnitude event without surcharging, and the 1:100yr magnitude event with surcharging but without flooding, and the 1:200yr magnitude event plus a 35% allowance for climate change can flood but the water should be managed in a way to not impact gardens / finished floor levels of properties. Safe dry access and egress is to be maintained at all times during flood events (see Section 7.2.1 of footnote 4). 4.36 The Gully Cleaning budget forms part of the wider Roads Revenue, Routine and Cyclic (R&C) budget. A general budget split and for monitoring purposes approximately £340k per annum (35% of R&C) has historically been aligned to gully cleaning. This is often insufficient to meet requirements with other elements of the R&C budget (temporary defect repairs, lining, drainage, signs etc) required to be reduced in year to balance the overall R&C budget. 4.37 The following table indicate spend on gully cleansing over the last 4 years. 20/21 21/22 22/23 23/24 Allocation (£) 334K 340k 436k 436k** Spend (£) 252k* 437k 444k £443k Number cleansed 20,777 22,675 18,922*** 22,208 *Covid affected spend **£42k R&C budget uplift all allocated to gully cleansing *** recording system down for several months requiring manual records to be kept 3 Harper-Macleod – Common Law Flooding: https://tinyurl.com/CLawFlood 4 Scottish Water – Sewers for Scotland v4: https://tinyurl.com/S4Sv4
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5. PROPOSALS 5.1 Continue to cleanse gullies utilising the plant and workforce of TC in accordance with current regime. 5.2 Continue to monitor and report against the target cleanse programme. 5.3 Budget and market availability permitting, hire in additional gully cleansing capacity to achieve targets. 5.4 As a result of some structural changes in the Flooding team, newly established Watercourse Inspector posts, once filled, will provide some additional capacity to engage with landowners and farmers. Whilst inspecting watercourses on private land these officers will discuss mitigations to prevent uncontrolled run-off to neighbouring land, be that private or public land. 5.5 In addition the Flood Liaison Officer in the RMP will engage with landowners and farmers at known regular overland flow locations that impact on the road network. 6. CONCLUSION 6.1 Without a recurring increase in revenue budget allocation it is not possible to proactively cleanse additional gullies, piped systems and ditches beyond the existing levels highlighted in para 4.24. 6.2 Officers and TC road workers will continue to endeavour to cleanse as many gullies as possible based on the most efficient and effective use of the resources at the Council’s disposal. 6.3 It should be acknowledged that taking resources from planned works to travel the Council area (lost travel time) to cleanse a gully that is potentially not blocked impacts on the workforces’ ability to achieve targets. Support is required for officers to use available resources efficiently and effectively. 6.4 It should be recognised that gullies are not in place to prevent flooding but to collect routine rainfall in a controlled manner and despatch water as pipework capacity allows. Gullies could be cleansed at an increased frequency however ultimately the capacity of the drainage network will always be the limiting factor for dispersing excess surface water.
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Author Name Designation Contact Details Stuart D’All Road Maintenance Partnership Manager 01738 475000 ComCommitteeReports@pkc.gov.uk Approved Name Designation Date Fraser Crofts Strategic Lead – Environment & Infrastructure 19 August 2024 APPENDICES Appendix 1 - Previous System Cleanse Monitor Outputs Appendix 2 – Cleanse Monitor 2023/24 Appendix 3 - Visual Representation
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ANNEX 1. IMPLICATIONS, ASSESSMENTS, CONSULTATION AND COMMUNICATION Strategic Implications Yes / None Community Plan / Single Outcome Agreement Yes Corporate Plan Yes Resource Implications Financial Yes Workforce Yes Asset Management (land, property, IST) None Assessments Equality Impact Assessment None Strategic Environmental Assessment None Sustainability (community, economic, environmental) None Legal and Governance None Risk Yes Consultation Internal None External None Communication Communications Plan None 1. Strategic Implications Community Plan / Single Outcome Agreement 1.1 Gully cleansing is part of the Councils statutory duties as Roads Authority, under the Road (Scotland) Act 1984, to manage and maintain all such roads in their area as are for the time being entered in their list of public roads. 1.2 Gully cleansing increases road safety by removing the potential of standing water on the road and consequential road traffic accidents or other loss/damage that could occur. Corporate Plan 1.3 The Council’s Corporate Plan for Securing the Future 2018 and Beyond lays out five Objectives which provide clear strategic direction, inform decisions at a corporate and service level and shape resources allocation. This report impacts on the following:- i) Promoting a prosperous, inclusive and sustainable economy ii) Supporting people to lead and independent, healthy and active life iii) Creating a safe and sustainable place for future generations 2. Resource Implications
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Financial 2.1 Gully cleansing is funded from an overall revenue budget for routine and cyclic activities incurred in maintaining the road network. 2.2 An enhanced cleansing regime is not possible within existing financial allocations. Additional non-recurring allocations will have minimal impact due to nature of the activity and difficulty engaging 3rd party private hire companies. Workforce 2.3 The staff and the operatives of Tayside Contracts and the Council who provide the service, have finite time to deliver this aspect of the overall service. Any additional outputs required would need to be adequately resourced. 3. Assessments Equality Impact Assessment 3.1 No assessment has been carried out into this activity. Strategic Environmental Assessment 3.2 No assessment has been carried out into this activity. Gully arisings have been treated through a reed bed system to remove pollutants prior to the water going back into the ecological system for in excess of 15 years and no change is proposed. Sustainability 3.3 No assessment has been carried out into this activity. Risk 3.4 The Council as Roads Authority have a statutory duty as set out in Roads Authority, under the Road (Scotland) Act 1984, to manage and maintain all such roads in their area as are for the time being entered in their list of public roads. 3.5 This activity enables the Council to meet its statutory obligations and minimise exposure to risk by cleansing gullies within the constraints of its finite resources. During severe weather, the Council will endeavour to mitigate the impacts by cleansing gullies likely to impact property flooding, as quickly as possible. 4. Consultation
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Internal 4.1 Nil. 5. Communication 5.1 Nil. 2. BACKGROUND PAPERS 2.1 Well Managed Highway Infrastructure 2016 2.2 Road (Scotland) Act 1984