An Audit of the Surface Water Outfalls in the River Ravensbourne - ‘Outfall Safari’

An audit of the surface water outfalls in the River Ravensbourne - ‘Outfall Safari’ December 2017 UK & Europe Conservation Programme Zoological Society of London Regent's Park London, NW1 4RY [email protected] www.zsl.org/conservation/regions/uk-europe/london’s-rivers Acknowledgements This project, funded by The Rivers Wetlands and Community Days Fund and City Bridge Trust, has been delivered in partnership with Thames21 with the support of the Environment Agency and Thames Water. It would not have been possible without the help of all the dedicated volunteers who collected the data. Introduction Misconnected wastewater pipework, cross-connected sewers and combined sewer overflows are a chronic source of pollution in urban rivers. An estimated 3% of properties in Greater London are misconnected (Dunk et al., 2008) sending pollution, via outfalls, into the nearest watercourse. There is currently no systematic surveying of outfalls in rivers to identify sources of pollution and to notify the relevant authorities. The ‘Outfall Safari’ is a survey method devised to address this evidence gathering and reporting gap. It was created by the Citizen Crane project steering group which consists of staff of Thames Water, Environment Agency (EA), Crane Valley Partnership, Friends of River Crane Environment, Frog Environmental and the Zoological Society of London (ZSL). It was first used on the River Crane in May 2016. Aims The aims of the River Ravensbourne Outfall Safari were to: Record and map the dry weather condition behaviour of surface water outfalls in the Ravensbourne catchment rivers; Assess and rank the impact of the outfalls and report those that are polluting to the Environment Agency and Thames Water; Build evidence on the scale of the problem of polluted surface water outfalls in Greater London; and Recruit more volunteers and further engage existing volunteers in the work of the Ravensbourne Catchment Partnership. 12 Method The survey of outfalls was conducted between 11th October and 9th November 2017. In total, 23 trained volunteers took part in the Outfall Safari. Volunteers were trained at the Lewisham Arts Café in Manor Park. Training, delivered by ZSL, Thames21 and Thames Water included: An overview of water quality issues in the River Ravensbourne; Information on outfalls and how they become polluted; Information on Thames Water’s surface water outfall team; Instruction on how to assess each outfall using the project App and how to upload information to the database; and A health and safety briefing and signing of the risk assessment. During the training, volunteers were assigned lengths of the River Ravensbourne to survey. Further coordination of survey dates and reaches was conducted by the volunteers on a closed Facebook group set up specifically for the Outfall Safari. Groups of volunteers were free to conduct the survey of their reach when convenient to them, within the survey period, provided there had been no rain for 48 hours prior to survey. A period of 48 hours of no rain is required before any survey work as rainfall and high surface water flows can obscure the negative impacts of outfalls by washing away sewage fungus, discoloured sediments and rag. Approximately 28.7km of the River Ravensbourne was surveyed by the Outfall Safari in total. Of this, 25.25km was surveyed by Thames21 and volunteers and 3.45km was surveyed by the Environment Agency (see Figure 1). Typically, the majority of the survey work for an Outfall Safari would be conducted from the riverside path, with only the occasional need to enter the river to properly assess and photograph outfalls. This is because Outfall Safari surveys are generally led by volunteers only, working in pairs (as a minimum) or groups. However, for the River Ravensbourne Outfall Safari volunteers were accompanied by Thames21 staff on surveys, as well as ZSL staff on some occasions. In these cases, and where river depths were low enough, surveys were conducted in- channel. The risk assessment for riverside outfall surveying highlighted the need to assess conditions in the river before entering it and stressed that volunteers should only enter the river channel if the level was lower than Wellington boot depth (c. 35cm). During the training volunteers were 13 also shown images of Giant Hogweed (Heracleum mantegazzianum). It was essential that volunteers could identify Hogweed before undertaking any survey work as it is a relatively common plant along the banks of rivers in Greater London and can burn and blister skin if touched. Waders and stabilising poles were used by in-channel survey teams. In addition to personal protective equipment (PPE) volunteers took a printed handout, designed to help with ranking the impacts of each outfall, and a smart phone or tablet loaded with a specially created data entry app. 14 Key – A Section A: Deptford Creek mouth to Deptford Bridge (TQ 37804 A 77753 to TQ 37426 77022) Section B: Deptford Bridge to Lewisham town centre (TQ 37416 B B F 76890 to TQ 38156 75895) Section C: Lewisham town centre to Catford, South Circular (TQ C 38142 75774 to TQ 37327 73569) G Section D: River Pool, South Circular to Southend Lane (TQ 37257 73384 to TQ 36965 71652) Section E: Southend Park to Cator Park (TQ 37051 71446 to TQ D H 36385 69987 and to TQ 36620 70047) I Section F: River Quaggy, Lee High Road to Cator Park (TQ 38403 75574 to TQ 40891 75026) Section G: Tudway Road to Dowding Drive (TQ 40968 74972 to TQ 41254 74703) E Section H: South Circular to Chinbrook Meadows (TQ 41302 74597 to TQ 41026 71834) Section I: River Ravensbourne, Linear Park to Ravensbourne Avenue (TQ 37276 73045 to TQ 39282 69556) O J Section J: Recreation Road to Glassmill Lane (TQ 396151 69268 to TQ 39844 69121) K Section K: Westmoreland Road to Hayes Road (TQ 40321 68500 Q to TQ 40424 68091) P L Section L: B265 to London South East Colleges, Bromley (TQ M 40614 67928 to TQ 41448 67176) N Section M: Bromley Common to Turpington Lane (TQ 41884 67258 to TQ 42117 67032) Section N: Crofton Road to Sparrow Drive (TQ 44105 65854 to TQ Legend River Surveyed 44383 66386) Section O: Clock House to Elmers End (TQ 36434 69457 to TQ 35917 68455 and TQ 35618 68724) Figure 1 – Map of Area of River Ravensbourne Surveyed Section P: Stone Park Avenue to Langley Sports Ground (TQ 37669 68424 to TQ 37692 67331) Section Q: Chaffinch Brook, railway to Fairford Avenue (TQ 35806 67936 to TQ 36039 67603) The App For ease of data collection from the river, the volunteers used an app created in Epicollect 5 (five.epicollect.net). Created by researchers at Imperial College, Epicollect is free and openly available. Once a project is set up in Epicollect it provides an app for remote data collection and upload, usable on GPS enabled smart phones, and a web portal to access and download the data. The outfall assessment form created in the app consisted of ten questions for volunteers to fill in at each outfall. The questions are taken directly from the form that Thames Water use for assessing the impact of outfalls and are shown in Table 1. Table 1 – Questions used in the Epicollect app to assess each outfall and their corresponding Impact Score Question Options EA score 1. Volunteer name 2. Date of survey 3. GPS location 4. Photo of the outfall 5. Description of the nearest landmark 6. Which bank is the outfall on (when looking downstream) 7. Ranking of the flow coming out of the outfall a. No Flow b. Trickle c. Low Flow d. Moderate Flow e. High Flow 8. Ranking of the visual impact of the outfall a. No visible effect 0 b. Within 2m of outfall 2 c. Impact 2 to 10m 4 d. Impact 10 to 30m 6 e. Impact greater than 30m 10 9. Ranking of the aesthetics of the outfall a. No odour or visible aesthetics 0 b. Faint smell, slight discolouration 2 c. Mild smell, mild discolouration, small 4 coverage of sewage fungus d. Strong smell, strong discolouration, large 6 coverage of sewage fungus and/ or litter e. Gross smell, gross sewage 10 10. Other signs of pollution Conversion of Outfall Assessment to Impact Scores To assist with prioritisation of the outfalls, the Environment Agency provided a method of converting the assessment data to a numeric impact score for each outfall. These scores are shown in the right hand column in Table 1. Reporting Volunteers are advised at the time of training that any outfall with an impact score ≥ 10, from the options in questions 8 and 9, should be reported directly from the river to the Environment Agency’s Incident Hotline and Thames Water. Both Thames Water and Environment Agency also receive a copy of this report. Data Processing Outfall data were checked to remove double entries and longitude and latitude coordinates were converted to National Grid References using www.gridreferencefinder.com. Results The volunteers photographed, located and assessed a total of 198 outfalls. Of this total 73 showed some signs of pollution and scored ˃ 0 and of these 38 had a score ≥ 4. The details of 31 outfalls with an impact score of ≥ 4 are given in Table 2. Six outfalls that volunteers scored ≥ 4 have not been included in Table 2 for further investigation (photo ID numbers 36, 60, 61, 122, 191 and 193). Those outfalls showed accumulations of a red-brown ‘slime’ (see Figure 2) that is likely to be a bacteria that proliferates by oxidising iron in the water (‘iron mould’) and is not related to misconnections. 12 Figure 2 - Examples of ‘Iron Mould’ Around Outfalls on the River Ravensbourne One outfall (photo ID number 150), located on the left bank near to 32 Mottingham Lane, SE12 9AN (TQ 41216 73656), is not included in Table 2 either as the pollution assessment indicated the presence of oil, rather than pollution as a result of a misconnection (impact score 4) (see Figure 3).

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