diffuse or not diffuse, that is the question? · 2018. 11. 21. · diffuse or not diffuse, that is...

DIFFUSE OR NOT DIFFUSE, THAT

IS THE QUESTION?

Investigating Reasons for Not Achieving Good Status in

Urban Catchments under the Water Framework Directive

Clare Deasy (NWG), Alistair Dalton (Wood), Paul Davison (Wood), Mark Barnett

(Wood), Andy Tweddle (Stantec), Steve Parkinson (Stantec), Mike Bowes (CEH), Matt

Loewenthal (EA), Sue Horsfall (NWG), Ashley Ferguson (NWG), et. al. 18/07/2018

CONTENTSCONTENTS

1 Introduction

2 Project Scope

3 Our Team

4 Phase 1

5 Phase 2

6 Project conclusions & Next steps

2

INTRODUCTION

3

• Northumbrian Water Group (NWG)

agreed with the EA to undertake phased

investigations into 5 waterbodies (3

catchments) where phosphate and/or

ammonia exceeded Water Framework

Directive (WFD) limits, and evidence

suggested intermittent sewage discharge

was the principal reason for not

achieving Good Status.

4

INTRODUCTION

INTRODUCTION

• Intermittent sources include:

– Combined Sewer Overflows (CSOs)

– Storm Tanks at Sewage Treatment Works

(STW)

– Emergency Overflows (EO’s) at Sewage

Pumping Stations (SPS)

– Polluted Surface Water Outfalls (PSWO)

5

SECTION HEADER ONE

PROJECT SCOPE

• Investigations broken into 4 phases:

– Phase 1: Understanding the catchment (desk based scoping study)

– Phase 2: Monitoring, initial analysis and identification of potential solutions

– Phase 3: Analysis and construction of modelling tools

– Phase 4: Developing cost-effective solutions

• NWG drew together a diverse and expert project team to undertake these

investigations:

– Framework consultants as leads (Wood & Stantec)

– Research consortium to support (identified through expression of interest)

– Key catchment partners to understand catchment pressures and issues

6

INTRODUCTION

OUR TEAM

Clare Deasy

NWG

Catchment

Approach

Coordinator

7

INTRODUCTION

Alistair Dalton

Wood.

Principal Modeller &

Project Manager

Paul Davison

Wood.

Associate Director,

Water

Management

Ashley

Ferguson

NWG

Project

Manager

Matt

Loewenthal

EA National

Water Quality

Instrumentation

Service

Technical Lead

Mark Barnett

Wood.

Principal

Consultant, Water

Management

Andy Newton

EA National

Water Quality

Instrumentation

Service

Field Scientist

Mike Bowes

CEH

Nutrient

Hydrochemist,

River Water

Quality and

Ecology

Andrew

Tweddle

Stantec

Senior Modeller,

Sewerage

Systems

Steve

Parkinson

Stantec

Principal

Modeller,

River Water

Quality

8

PHASE 1

Understanding the catchments (scoping study)

UPPER TEAM CATCHMENT - OVERVIEW

• WFD Waterbody Covering 1,662ha

• Includes the Urban Areas of Annfield Plain

and Stanley

• Upper Team is a Tributary of the River Tyne

• 5.45km of Watercourse

• Hydromorphological Designation: Heavily

Modified

• NWG Assets:

• 1 Drainage Area • 29 Surface Water Outfalls

• 18 CSOs • 4 Storage Tanks

• 6 SPSs • 2 Septic Tanks

• 7 CSO Outfalls • 1 Sewage Treatment Works

9

PHASE 1: UNDERSTANDING THE CATCHMENT (SCOPING STUDY)

TWIZELL BURN CATCHMENT - OVERVIEW

• WFD Waterbody Covering 1,896ha

• Includes the Urban Area of South Stanley

• Twizell Burn is a Tributary of the River Wear



Modified

• NWG Assets:

• 1 Drainage Area • 15 Surface Water Outfalls



• 10 CSO Outfalls • 1 Sewage Treatment Works

10


LUMLEY PARK BURN CATCHMENT - OVERVIEW

• Three WFD Waterbodies Covering 5,332ha

• Includes the Urban Areas of Houghton-Le-

Spring, Hetton-Le-Hole and New Herrington

• Lumley Park Burn is a Tributary of the River

Wear

• Moors Burn

• Herrington Burn



Modified

• NWG Assets:

• 4 Drainage Areas • 83 Surface Water Outfalls



• 16 CSO Outfalls • 1 Sewage Treatment Works11


DATA SOURCES

• NWG GIS Data for Sewer and Surface

Water Network & Assets

• Existing WasteWater Hydraulic Models

• Geology/Soil Data

• Land Use Data Inc. Agricultural

Census & CEH Land Cover Map

• Protected Areas

• Continuous and Intermittent Discharge

Details, Locations and Consents

• Known Sources of Phosphate and

Ammonia

12


• Polluted Surface Water Outfalls

• Consented Trade Effluent Discharges

• CSO Sewer Level Monitor data

• Previous Studies

• Rainfall & River Flow Data

• Existing EA Sample Data

• EA Source Apportionment GIS

(SAGIS) Results

• EA National Incident Reporting

System (Pollution Incidents)

METHODOLOGY

• Water Framework Directive Baseline

– Water Body Classification (2015)

– Water Body Objectives

– Potential Point & Diffuse Sources of Phosphate and Ammonia:

• Agriculture • Landfill Sites • Mines and Extraction Discharges • Geology

• Combined Sewer Overflows • Sewage Treatment Works • Urban-Runoff • Industrial discharge

• Septic Tanks • Burial Sites • Atmospheric deposition • Mains water leakage

– Supporting Elements:

• Dissolved Oxygen • BOD • Conductivity • Suspended Solids

• Fish • Invertebrates • Nitrate • pH

• Temperature • Metals • Sulphate

13


METHODOLOGY

• Catchment Source Conceptualisation

– Review of Previous Studies

– General Phosphate and Ammonia Trends Across the Catchments

– Conceptualisation of Individual Waterbodies from EA Sample Data:

• Phosphate

• Ammonia

• Conductivity, DO, Nitrate and pH

• Ecology

• Other Evidence

• Summary of Potential Sources of Phosphate and Ammonia

14


METHODOLOGY

• Phosphorous Source Apportionment

– Two Methodologies:

• Source Apportionment GIS (SAGIS) Results

• Phosphorus Indicators Tool (PIT) (Heathwaite et al, 2003)

– Calculation of Catchment Phosphate Budget

• Ammonia Water Quality Modelling

– Existing Hydraulic Models:

• InfoWorks ICM

• Annual Time Series Rainfall

• Intermittent Discharge Spill Frequency and Volume

– Non-Sewage Sources of Ammonia

• Landfill Sites

• Agriculture

15


PIT - Modelled sources and pathways of Phosphorus

OUTPUTS

• River Team– Evidence confirmed some water quality issues.

– However, overall phosphate budget dominated by STW final effluent discharge. No

evidence to link historic high phosphate sample concentrations to normal CSO

operation.

– Further evidence from Chemicals Investigation Programme (CIP) on the Upper Team

indicated an unknown dry weather phosphate discharge.

– Insufficient evidence to confirm specific sources of ammonia.

• Twizell Burn– Evidence indicated marginal compliance with WFD standards for phosphate and

ammonia.

– No evidence to link historic high phosphate sample concentrations to normal CSO

operation. Phosphate budget indicated a modest contribution from CSO discharges.

– Insufficient evidence to confirm specific sources of ammonia.

• Lumley Park Burn (3 x WFD Catchments)

– Evidence indicated compliance with WFD Good Status for ammonia in all 3

waterbodies.

– No evidence to link historic high phosphate sample concentrations to normal CSO

operation. Phosphate budget indicated a modest contribution from CSO discharges.

– Insufficient evidence to confirm specific sources of ammonia.16


SAGIS Output

PIT Output

Waterbody

phosphate

budget

KEY RECOMMENDATIONS

17


• River Team

– No further action to be undertaken in respect of phosphate or ammonia discharges from CSOs – STW discharge

predominant and is to be addressed separately.

– In Phase 2, investigate an unknown continuous source of phosphate identified from Chemicals Investigation Programme

(CIP) investigations on the Upper Team.

• Twizell Burn

– In Phase 2, continue to investigate potential sources of pollution affecting ammonia and Phosphates compliance with WFD

standards.

– Undertake ammonia, phosphate and supporting water quality monitoring, supported with ecology (invertebrate) sampling

and collection of sewer and river flow data and rainfall.

– Undertake further outfall inspections and sampling as necessary to identify pollution sources.

• Lumley Park Burn (3 x WFD Water Bodies)

– No further action to be undertaken in lower Waterbody – problems predominantly due to STW continuous discharge (to be

addressed separately).

– Undertake ammonia, phosphate and supporting water quality monitoring, supported with ecology (invertebrate) sampling

and collection of sewer and river flow data and rainfall.

– Undertake further outfall inspections and sampling as necessary to identify pollution sources.

– Phase 2 Investigations to concentrate on Phosphates.

18

Monitoring, initial analysis and identification of potential solutions

PHASE 2

UPPER TEAM CATCHMENT – MONITORING AND FINDINGS

Monitoring

• Misconnection surveys (January - June 2017) to investigate cause of elevated dry

weather phosphate recorded in CIP project

• 7 Outfalls and 12 watercourse sites inspected and spot sampled

Findings

• Single dry weather phosphate source identified from tributary culvert for potential further

investigation

19

PHASE 2 - MONITORING, INITIAL ANALYSIS AND IDENTIFICATION OF

POTENTIAL SOLUTIONS

Summary:

Focused survey established the likely area of high phosphate

discharge to be in a location where NWG have no assets.

TWIZELL BURN CATCHMENT - MONITORING

• Water Quality (March to September 2017)

• 5 Continuous High Resolution Sondes (N/DO/pH/Temperature/Salinity/Suspended Solids/Nitrate & Nitrite/chlorophyll a)

• 1 Auto Sampler (Reactive) (N/DO/pH/Temperature/Salinity/Metals/Ions/Suspended Solids/Phosphorus&

Phosphates/Nitrate & Nitrite/Boron)

• Fortnightly Spot Sampling at 6 Sites (N/DO/pH/Temperature/Salinity/Metals/Ions/Suspended Solids/Phosphorus&


• Outfall Spot Sampling (N/DO/pH/Temperature/Salinity/Metals/Ions/Suspended Solids/Phosphorus&


• Culvert Biofilm and Cytometry(Upstream and downstream of Stanley Burn Culvert, by Mike Bowes, CEH)

• In-Sewer Flow Monitoring (September 2016 to July

2017)

• 10 Flow Monitors and 4 Rain Gauges

• Ecology (June 2017)

• RiverFly/Kick Sampling at 5 sites

• Misconnection Surveys (May 2017)

• 16 Outfalls Inc Spot Sampling

20


POTENTIAL SOLUTIONS

TWIZELL BURN CATCHMENT - FINDINGS

• Water Quality • High conductivity explained by the presence of metals in the water.

• Ammonia consistent with the EA’s WFD classification (Good status)

upstream of the STW.

• Phosphates consistent with WFD Good status EQS for most of the

sampling period upstream of the STW, but some anomalies investigated

with further outfall sampling indicated possible non-sewage sources.

• Wet weather sample data supported Phase 1 conclusion that intermittent

discharges have a relatively low impact on ammonia and phosphate.

• Ecology• RiverFly BWMP and ASPT scores were all assessed as Poor or

Moderate for biology and water quality.

• Indicates an overall problem with the condition of the Burn rather than

problems with any specific pressure. However, based on only one

sample.

• Flow cytometry and biofilm measurements by CEH identified localised

adverse effect of Stanley Burn culvert.

• Misconnection Surveys • No significant water quality issues observed.

21


POTENTIAL SOLUTIONS

Summary:

Although the monitoring

and ecology data did

indicate some water

quality related issues

there was no evidence

that intermittent

discharges are causing

WFD failures in this

waterbody.

LUMLEY PARK BURN CATCHMENT - MONITORING

• Water Quality (March to September 2017)

• 9 Continuous High Resolution Sondes (N/DO/pH/Temperature/Salinity/Suspended Solids/Nitrate & Nitrite)

• 2 Auto Samplers (N/DO/pH/Temperature/Salinity/Metals/Ions/Suspended Solids/Phosphorus&


• Fortnightly Spot Sampling at 9 Sites (N/DO/pH/Temperature/Salinity/Metals/Ions/Suspended Solids/Phosphorus&


• Wet Weather/Ad-Hoc Spot Sampling (N/DO/pH/Temperature/Salinity/Metals/Ions/Suspended Solids/Phosphorus&


• In-Sewer Flow Monitoring (October 2016 to July 2017)

• 24 Flow Monitors & 8 Rain Gauges

• Ecology (July 2017)

• RiverFly/Kick Sampling at 9 sites

• Misconnection Surveys (August 2017)

• 44 Outfalls Inc Spot Sampling

22


POTENTIAL SOLUTIONS

LUMLEY PARK BURN CATCHMENT - FINDINGS

• Water Quality

• High conductivity explained by the presence of metals in the water.

• No evidence of intermittent discharges having any impact on DO levels either

directly or through leading to elevated levels of nutrients in the waterbody.

• Ammonia consistent with the EA’s WFD classification

• Spot sampling data indicated high phosphate levels – No correlation with

boron and phosphate and high iron levels during rainfall so unlikely sewage

source (groundwater and diffuse sources).

• No clear patterns which identified significant impacts from intermittent

discharges on ammonia or phosphates.

• Ecology

• RiverFly BWMP and ASPT scores were all assessed as Poor or Very Poor for

biology and water quality.

• Indicates an overall problem with the condition of the Lumley Park Burn rather

than problems with any specific pressure. However, only one sample.

• Misconnection Surveys

• No significant water quality issues but some evidence of sewer misconnection

and groundwater infiltration.

23


POTENTIAL SOLUTIONS

Summary:

Although the monitoring and

ecology data did indicate some

water quality related issues and

that there was the potential for

some misconnections and

groundwater infiltration into

NWG networks, there was no

evidence that intermittent

discharges are causing WFD

failures in this waterbody.

24

CONCLUSIONS &

NEXT STEPS

PROJECT CONCLUSIONS AND RECOMMENDATIONS

25

CONCLUSIONS AND NEXT STEPS

• Overall there was no evidence in any of the studies that indicated NWG

assets were operating inappropriately or that intermittent discharges are

having a significant effect on water quality or WFD classification.

• Recommendations:

– None of the studies were recommended to be progressed to Phase 3;

– NWG should continue to closely monitor CSO performance via Event Duration Monitors;

– NWG should continue to monitor and address misconnections in the catchments through the

PSWO programme.

– The EA, supported by local river trusts, should undertake further periodic water quality and

invertebrate sampling at key sites in the watercourse to enable the impact of any measures to be

assessed; and

– Working with local partners to help improve the watercourses could also be undertaken including:

• Reducing diffuse inputs from various land use

• Improving WQ in ponds and lakes at the top of catchments (Lumley Park Burn)

• Instream habitat improvements to make watercourse and ecology more resilient (e.g. culvert

daylighting)

BENEFITS OF COLLABORATIVE APPROACH

• More efficient – involvement of EA WQ Instrumentation Team

helped speed up processes for selecting instrumentation, accessing sites,

and implementing monitoring.

• More expertise – involvement of CEH and EA WQ Instrumentation

Team helped understand issues and challenges, put in place the right

approach, and interpret the data. Also Consultant expertise sharing.

• Assurance – involvement of EA WQ Instrumentation Team helped

reassure the EA that the data we collected was high quality and could be

trusted.

26

CONCLUSIONS AND NEXT STEPS

NEXT STEPS

• Work with local partners within Catchment Based Approach to build on

findings of investigations and work together to improve WFD status within

the catchments

• Investigate frequently spilling CSOs within these catchments through

Storm Overflow Assessment Framework under 21st Century Drainage

(Included in Water Industry National Environment Programme for PR19)

• Work with EA to extrapolate findings to other waterbodies where

intermittent discharges are main reason for failure to meet WFD Good

Status

27

SECTION HEADER ONE

THANK YOU

diffuse or not diffuse, that is the question? · 2018. 11. 21. · diffuse or not diffuse, that is...

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