UK Spill Seminar October 2018

1. Consequences of Spills on Public Drinking Water Supply and Expectations from Responders UK Spill Seminar October 2018 James Bucknall – Water Quality Scientist Portsmouth Water

2. Presentation contents: Introduction to Portsmouth Water, groundwater flow and drinking water supply systems Domestic heating oil spills and their distribution The impact of spills on Portsmouth Water’s operations Portsmouth Water’s expectations from responders Portsmouth Water awareness campaign and oil tank replacement scheme

3. Introduction to Portsmouth Water • Area covered - 868Km2 • Length of mains: 3,297 km • 316,000 domestic properties • 16,500 business properties • 725,000 population • Average daily distribution input: 169 million litres per day

4. Water Resources at Portsmouth Water • Water resources: • 18 Chalk groundwater abstractions – boreholes/wells • 50% contribution to supply • 1 karstic Chalk groundwater spring system – 28 individual springs utilised • 35% contribution to supply • 1 river abstraction – Chalk groundwater fed • 15% contribution to supply

5. Solution features in the Chalk • Clay deposits concentrate flow of surface water • Clay makes water acidic • Acidic water enlarges fractures • Allow for very rapid travel groundwater flow • Tracer tests = >2.5km/d

6. Chalk Groundwater flow – dual permeability • Source Protection Zones do not consider rapid flow • Groundwater in chalk flows via 2 different mechanisms: • Matrix - SLOW • Fractures and fissures - FAST • Tracer studies have proven that fracture and fissure flow can exceed 2.5km/d in some localised areas

7. Typical Portsmouth Water Supply System • Water companies operate multiple, discreet ‘Supply Systems’ to provide clean, wholesome water to their consumers • A ‘Supply System’ is defined as a group of assets that are connected from catchments through to consumers taps to indicate the transfer of water from source to tap for a discreet area of the drinking water supplier’s water network • Assets include: • Groundwater and surface water catchments • Treatment works • Raw water reservoirs • Service reservoirs – treated water • Distribution network

8. Typical Portsmouth Water Supply System Catchment 3 Catchment 1 Catchment 2 20 ML/D 10 ML/D 10 ML/D Treatment works 3 Treatment works 2 Treatment works 1 Supply System Transfer Service Reservoirs (typically 3 on one site) Service Reservoir 25 ML/D requirement Water Supply Zone 15 ML/D production headroom

9. Distribution and location of domestic heating oil spills

10. An on-going problem - Domestic heating oil storage • Our groundwater catchments are rural areas - no connections to mains gas - high frequency of domestic heating oil storage (kerosene) • Home owners do not know that they live in SPZs and the risk that their oil storage poses to groundwater • No regulations in domestic setting to protect environment in sensitive areas – only advice (EA & OFTEC) • Failure to invest in system maintenance by home owners • Direct pathways to groundwater – soakaways, boreholes and ornamental wells

11. Direct pathway to groundwater • Ornamental well in Kitchen • 500 litres of kerosene entered groundwater • Kerosene detected in another well south of spill location

12. The impact of spills on Portsmouth Water’s operations • Long term shut down of one or more works - reduces production headroom and lowers resilience and increased likelihood of customers experiencing an interruption to supply. • Compounded by high demand (good weather) and drought • Significant input of staff time over the long term • Postponement of planned maintenance • Consultancy support costs – H20geo • Additional hydrocarbon monitoring – VOC • Potential for catastrophic loss of source – loss of resilience/increased risk of No Supply situation/new resource development (multiple million pound projects) • Scoping of new treatment requirements /monitoring - hydrocarbon treatment difficult • CAPEX • OPEX

13. Portsmouth Waters expectations from spill responders • What do we need from Spill Responders? • Early notification to the Environment Agency and Portsmouth Water • Full consideration of groundwater from the outset of the incident • A rapid, open, risk-based response – escalated response if SPZ1 and SPZ2 • How is this achieved? • Sharing of information and communication between PW and the Home-Owner, Spill Company (Consultant), Insurers, Loss Adjustor, Environment Agency and Environmental health • Preparation of a preliminary risk assessment including a Conceptual Site Model (CSM) including S-P-R model and potential linkages. • Scope of Anticipated Work • Detailed Report • Verification/Monitoring Report

14. Awareness campaign and tank replacement scheme • 2013 • Information leaflet sent to properties in SPZ1, that are not on mains gas. • 2014 – 2016 • Revised leaflet with offer of half price tank inspection by OFTEC registered technician for properties in SPZ1. Supported by OFTEC. • 2017 – 2019 • Subsidised oil tank, pipework and supporting base replacement for properties in SPZ1 whose tank is a risk to groundwater. Supported by OFTEC. • 2020 – 2025 • Subsidy scheme to be extended to include SPZ2 – additional 2500 properties and increased budget

18. Closing remarks • Groundwater a vital resource. However, it is often out of sight and out of mind • Groundwater must be considered during initial site assessments – the local community may rely on groundwater for drinking water • Early notification and a rapid, open, risk-based response is essential • Responders actions can help prevent the catastrophic loss of a public drinking water source • Other Water Companies may not be able to operate with as high network resilience as ourselves • Thankyou for listening • j.bucknall@portsmouthwater.co.uk

19. Appendix 1 • How is this achieved? • Sharing of information and communication between us and the Home-Owner, Spill Company (Consultant), Insurers, Loss Adjustor and Environment Agency. • Early notification of the spill/leak/incident with Portsmouth Water and the Environment Agency; • Detailed location – address and national grid reference; • Contact details of Spill Company/Consultant, Home/Business-owner, Insurance Company and Loss Adjustor; • Description of what happened, i.e. catastrophic loss or gradual leak, what estimated volume was lost and how was that calculated, what happened and how? Has the leak source been stopped and if so how? • What fuel infrastructure is on site? • What initial investigation works have taken place? Remedial trenching/trial pits, storage and remove of waste material, detailed log of volumes and sampling strategy – i.e. what concentrations have been recovered and what is the estimated mass recovery of product? • Preparation of a preliminary risk assessment including a Conceptual Site Model (CSM): • Details of what product was lost, how much and how? • Description of hard standing beneath spill site, above ground tank; • Soils, clay content, type and thickness (anticipated or actual); • Outline drainage scheme on site; • Description of Superficial Deposits and Bedrock Geology, thicknesses; • Hydrology and hydrogeology - Anticipated or actual groundwater elevations, nearby surface water features, anticipated flow direction; • Nearby borehole design, depths, adits, pumping rates, groundwater levels, • Presentation of the Preliminary Source, Pathway and Receptor Model identifying potential linkages.

20. Appendix 2 • Scope of Anticipated Work • Provide scope/details of proposed investigation, remediation and monitoring strategy in time for us to comment and respond. We may have specific requirements for drilling through polluted ground and there are vulnerabilities in our catchment such as solution features and adits linking abstractions, this information is essential to feed into the risk assessment and is not always publicly available. • Detailed Reports • Detailed report on site investigation (having already shared field reports) and risk assessment, updated conceptual site model including findings from the investigation. Each phase should build on the previous one adding more certainty and detail to the previous one. Based on the results we may wish to see further monitoring, modelling (fate and transport) and risk assessment. • Verification/Monitoring Report • The last phase to demonstrate the spill no longer poses a risk to ground/surface water (Controlled Waters).