Biodiversity and the Thames Tunnel

Stephanie McGibbon, EIA Manager12 May 2011

Contents

Overview of the Thames Tunnel project

Thames Tunnel EIA and Biodiversity

– Data gathering

– Initial findings

– Engaging with stakeholders

Questions

Project overview

Victorian infrastructure

Combined sewer system

57 Combined sewer overflows (CSOs)

Headline news

Thames Tunnel to intercept combined sewer overflows

Capturing the overflows

Environmental Impact Assessment (EIA) and Biodiversity

Stakeholder C

onsultation

EIA & reporting stages

Terrestrial ecology data gathering

Desk Study: GIGL data search and consultation

Use of Satellite/Geo-viewer Imagery

Phase 1 Habitat Surveys and Plans (completed)

Detailed Surveys for Protected/Notable Species (underway)

Terrestrial ecology: protected / notable species surveys

Bats

Birds (Breeding & Wintering)

Reptiles

Amphibians

Invertebrates

Otter and water vole

Botanical

Phase 1 terrestrial ecology surveys - extract

Site Habitats Species Potential

Abbey Mills Mature treesScrubSemi-improved grassland Disused buildings

BirdsBatsReptilesInvertebratesWater Voles and otterInvasive Plants

Acton Storm Tanks Amenity grasslandTall ruderal vegetationScattered trees

Wintering birdsBatsReptiles

Barn Elms Amenity grasslandSemi-improved grassland Tall ruderal vegetationScrubScattered treesRunning water

Breeding and wintering birdsBadgersBatsReptilesInvertebratesWater Voles and otter

Beckton STW ScrubScattered treesPlantation woodlandStanding water

Breeding and wintering birdsBlack redstartBatsReptiles

Aquatic ecology data gathering Desk study

– Environment Agency fish and invertebrate databases

– Mammal data

– Local Habitat Action Plan’s (HAPs)

Field surveys

– Construction and ‘Improvement’ sites

– Range of sites and spatial scope of survey

Fish surveys (autumn 2010)

Total fish

Invertebrates surveys (Autumn 2010)

Invertebrate diversity

Mean Diversity

0

2

4

6

8

10

12

14

Borth

wic

k W

hf

Kg E

dw

ard

Mem

Pk

Bla

ckfria

rs B

r

Vic

toria

Em

bkt

Alb

ert E

mbkt

Tid

ew

ay W

k

W P

um

pin

g S

tn

Chels

ea E

mbk

Cre

morn

e W

hf

Jew

s R

ow

Bell L

a C

rk

Putn

ey B

r

Barn

Elm

s

Ham

mers

mith

PS

t

No

Taxa

Subtidal sample

Intertidal sample

Mitigation hierarchy

REDUCE IMPACT

ABATE IMPACTS AT SOURCE

ABATE IMPACTS ELSEWHERE (as close to impact as possible)

COMPENSATE IN KIND

COMPENSATE BY OTHER MEANS

ENHANCE Enhancement

Compensation

Mitigation

AVOID IMPACT

Balance sheet

A B C D E F G

HabitatPermanent landtake for built footprint

Mitigation landtake

Total landtake Habitat creationHabitat enhancement

Total creation/ enhancement

Net loss/gain

Woodland Ha

Scattered Trees No.

Hedgerow M

Scrub Ha

Tall Ruderal Ha

Ornamental Planting/Introduced Shrub

Ha

Semi-improved Grassland

Ha

Amenity Grassland Ha

Short Perennial/Disused Ha

Standing Water/Wetland Ha

TOTAL (Semi-natural habitats)

Hard-standing (buildings and roads/tracks)

Ha

TOTAL (All habitats)

Engaging with stakeholders

A Thames Tunnel Biodiversity Forum has been established

– November 2010

– March 2011

Stakeholders

– 14 local planning authorities

– Environment Agency

– Natural England

– London Biodiversity Partnership

– Thames21

Background Information Slides

For reference

Bazalgette’s intercepting sewers

Thames Tideway Strategic Study

Two problems:

Overloaded sewage treatment works; discharging directly into the river after heavy rainfall

Overloaded sewer network; discharging into the river via CSOs.

Three solutions:

River

Brent

River Lee

River

Roding River Beam

River Ingrebourne

Sewage treatment works discharging to the tidal River Thames

Thames Estuary

Southend

Gravesend

Long Reach

Riverside

Crossness

Mogden

Beckton

The Lee Tunnel

Four mile tunnel from Abbey Mills to Beckton. To start and end on land we already own; requires no intermediate construction sites.

To intercept 16 million cubic metres of untreated sewage currently discharged into the River Thames each year on average, via the River Lee.

Planning consent granted, subject to planning conditions.

£600 million project – largest contract TWUL has ever awarded. Construction started in June 2010 and is scheduled to finish in 2014.

Birds

Objectives:

To obtain survey data on wintering birds and breeding birds at and adjacent to preferred work sites.

Approach:

A huge amount of data and local knowledge already exists on bird populations across London.

Proposed work sites will first be screened for inclusion in the survey.

Sites will then be further screened on the basis of current knowledge.

Methodology:

Survey methodologies would be developed.

Methodologies will be agreed in consultation with statutory agencies.

Bats Objectives: To obtain information on the following,

which could be affected by development works

i) roost sites, and

ii) any significant foraging or commuting routes

Gather and collate existing data

Phase 1 surveys will include a site evaluation

Initial use of remote monitoring equipment

Site surveys.

Surveys methodologies

Approach/Methodology:

There is a large pool of existing data on sites used by bats. The approach will be to: