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Consultation Meeting

Subgroup on the Lowermoor Water Pollution Meeting

INTRODUCTION

Frank Woods

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PROGRAMME (I) - Presentations

• Introduction• Water quality modelling • Health effects reported• Population studies • Information on contaminants• Final comments

We want to hear from YOU

PROGRAMME (II)

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WATER QUALITY MODELLING

Malcolm BrandtJames Powell

Black & Veatch Ltd

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System OverviewCrowdy Reservoir

Aluminium Sulphate(normally added in small quantity prior to settlement tank)

Settlement tank

LowermoorTreatment Works

Sand Filter

Contact Tank(Disinfection)

Storage Reservoir

Distribution Network

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Modelling Objectives

1. Investigate the extent of mixing (dilution) of the alum within the treatment works

2. Predict the peak concentration of alum in the water leaving the works

3. Simulate the spread of the alum through the network (trunk mains only)

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Approach

CFD model of contact tank

CFD = Computational fluid dynamics

• Models 3 dimensional fluid flow

• Widely used in engineeringe.g. design of aeroplanes, yachts, Formula one…..

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Approach

CFD model of contact tank

CFD model of storage reservoir

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Approach

CFD model of contact tank

CFD model of storage reservoir

Trunk main network model

• Tracks the slug of contaminated water through the pipes

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Contact tankLayout

Out

In62L/s

Alum 56,000mg/L6.8L/s

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Contact tankLayout

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Contact tankLayout

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Contact tankSimulation of Alum discharge

4300

3200

2100

1000

Concentration(mg/L Al)

0

8

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Contact tankPoints of Note

• Sinks to bottom and spreads

• Holes in wall cause most mixing

• Concentration at outlet falls rapidly after discharge ends

Outlet

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Approach

CFD model of contact tank

CFD model of storage reservoir

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Storage reservoirLayout

In

Out

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Storage reservoirSimulation of Alum

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Storage reservoirPredicted Outlet Concentration

• Peak entering network = 325 mg/L Al

• Corresponding acidity

0

75

150

225

300

375

0 6 12 18 24Time (hr)

Con

cent

ratio

n (m

g/L

Al)

0%

20%

40%

60%

80%

100%

% R

emai

ning

in ta

nkConcentration % Remaining in tank

6 July 8:40pm

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Storage reservoirPredicted Outlet Concentration

• 60% still in tanks after 6hr (6 July 11:00pm)

• 25% still in tanks after 12hr (7 July 5:00am)

0

75

150

225

300

375

0 6 12 18 24Time (hr)

Con

cent

ratio

n (m

g/L

Al)

0%

20%

40%

60%

80%

100%

% R

emai

ning

in ta

nk

Concentration % Remaining in tank

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Approach

CFD model of contact tank

CFD model of storage reservoir

Trunk main network model

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CAMELFORD

Tintagel

Boscastle

Delabole

LowermoorWater Treatment

works

Port IsaacSouth West

Water Network

Network modelMap

• Trunk (spine) mains only

• Model ‘drags’ the concentration profile from the clear water tank through the network

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Network modelSt Teath and Helston

0

50

100

150

200

250

300

350

Wed 06 Jul00:00

Thu 07 Jul00:00

Fri 08 Jul00:00

Sat 09 Jul00:00

Sun 10 Jul00:00

Mon 11 Jul00:00

Con

cent

ratio

n (m

g/L

Al)

Off 9" Delabole to St Endellion (1) SWW samples Private samples

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Conclusions

• Simulation of mixing in the tanks has been used to predict the peak concentrations

56,000 mg/L Al

1500 mg/L Al

325 mg/L Al

Lower after reservoirs

Peak

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Conclusions

• The time that the slug of contaminated water arrived at different locations has been estimated

56,000 mg/L Al

1500 mg/L Al

325 mg/L Al

Lower

6 July 5:00pm

Peak at

6 July 5:40pm

6 July 8:40pmDelabole Res In7 July 0:00am

St Endelion Res In8 July 6:00am

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Conclusions

• The slug of contaminated water will get delayed and maybe diluted in:– Reservoirs– Local mains– Consumer plumbing– Consumer tanks

56,000 mg/L Al

1500 mg/L Al

325 mg/L Al

Lower

6 July 5:00pm

Peak at

6 July 5:40pm

6 July 8:40pmDelabole Res In7 July 0:00am

St Endelion Res In8 July 6:00am

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POPULATION STUDIES

Lesley Rushton

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Population Studies

• Several studies have investigated the occurrence of various health problems including: – Symptoms immediately following the incident – Hospital treatment (hospital discharges)– Causes of death– Incidence of cancer/leukaemia

• Most of these studies have compared the population in the contaminated area with a population from another area

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Summary of Results

• Symptoms survey: More people in the contaminated area noticed changes in the water and reported symptoms.

• Hospital treatment rates increased slightly compared with other areas.

• Death and cancer rates are both lower than those of the whole of Cornwall.

• A study of Leukaemia cases in children showed a possible association with high rates of infection.

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Comments

• None of these studies are easy to carry out.

• None have good exposure data • Holiday makers were not included.• Information on other causes of the

diseases was often not available or not collected.

• In spite of these problems the results are generally reassuring.

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INFORMATION FROM INTERVIEWS

Anita Thomas

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Thank you

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General observations

Water quality and usage

Reported health effects in adults and children – acute and chronic

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Concerns about chronic effects

• Joints

• Memory, coordination and concentration

• Cancer

• Thyroid disease

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Nerves and brain

• Neuropsychological tests

• Study design

INFORMATION ON CONTAMINANTS

Kevin Chipman

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Hazard • What adverse effects may a chemical cause?

• How potent is it ?

Exposure • What was the dose ?

• For how long was exposure ?

Establish the likelihood of harm

Assessment of Risk

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• Information from human exposures

e.g. aluminium exposure from the use of antacid medication & kidney dialysis.

Look for evidence of harmful effects

Is there a dose that is SAFE (NO ADVERSE EFFECT) ?

• Effects in animals

What organs are affected by the chemicals ?

What is the dose that is SAFE ?

A. Short term exposure

B. Long term exposure

How Have We AssessedPotential for Harm ?

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Potential for Adverse Reactions to the Chemical Exposures at Lowermoor

What about the immediate effects of the short-term relatively high exposure?

• The chemicals probably caused some of the immediate effects.

• In particular, exposure to increased copper, zinc and sulphate (and the combinations) probably contributed to symptoms such as stomach ache and ulcers.

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What about the Possibility of Delayed or Persistent Harm to Health?

A focus on aluminium:

• Aluminium is hazardous• In particular in animals it can damage the brain, the liver,

kidney, bone and can affect the developing embryoBut!• If taken in drink, only small amounts reach the organs and

we clear it from the body quickly• The maximum SAFE dose for long term intake is close to

that in antacids. • The long term exposure was much lower than this safe dose • Delayed or persistent harm would not be expected

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Bottle-fed Children

• In babies, the dose may have been higher compared to adults

• Therefore the Subgroup considered that the risk (albeit unlikely) from aluminium and other metal exposures such as lead was greatest for bottle-fed infants.

• This explains why bottle–fed children have been highlighted as a group for which further studies have been recommended.

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Contaminants otherthan Aluminium

• Similar assessments were made for other metals (lead, copper, zinc, manganese, and iron as well as sulphate and acidity).

• We also considered possible combined effects of these contaminants

• These may have contributed to immediate effects on the intestine.

• Delayed or persistent effects from the exposures are unlikely.

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Particular areas given close attention

CANCER….. It is encouraging that the toxicology evidence on the contaminants generally did not give reason for concern about ability to cause cancers

ALZHEIMER’S disease……Although it has been considered in the past that aluminium may cause this disease, evidence now suggests that it is NOT a cause.

THYROID disease……There is no evidence to suggest that any of the contaminants concerned could have affected the thyroid

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Particular Gaps in Knowledge and the Need for Further Studies

• Neuropsychological studies (e.g. effects on

memory)

• Child development

• Joint problems

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FINAL COMMENTS

Frank Woods