Mercury – a Part IIa investigation

Mandy DennisSenior Environmental Protection Officer

An unlikely mix!

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Section 78A – Part IIA of the Environmental Protection Act 1990

• Cause their area to be inspected to identify Contaminated Land• Statutory requirement to produce an inspection strategy• To determine whether a site is “contaminated land”• To act as enforcing authority for contaminated sites (other than

special sites)• Determine what remediation is required and ensures that it takes

place• Establish responsibility for remediation• Decides who bears what proportion of liability/cost of remediation• Maintain a Public Register

What is contaminated land?

• Land is legally defined as ‘contaminated land’ where substances are causing or could cause:

• significant harm to people, property or protected species• significant pollution of surface waters (for example lakes

and rivers) or groundwater• harm to people as a result of radioactivity

Source GOV.UK (not the legal definition)

Pollutant linkage• Source • Pathway• Receptor

Must be plausible

Planning and land affected by contamination• Majority of remediation is carried out via the planning process• NPPF • Section 111 encourage effective use of brownfield land• Section 120 prevent unacceptable risks from pollution an land

instability• Section 120 responsibility for safe development lies with the

developer/landowner• Section 121 suitable for use taking into account previous use• Section 121 after remediation land should not be capable of

being determined as contaminated land under Part IIA

Mercury can be highly toxic• Inorganic• Organic (methylmercury)• Metallic

• Minamata disease• Health effects• Toxic to the nervous system• Damage to lungs, kidneys, digestive tract• Neurological and behavioural disorders• Tremors, insomnia, memory loss,

headaches• Foetal damage• The list goes on

Always expect the unexpected!Mercury (total) found across the site ranging from 0.7mg/kg to 390mg/kg

SGV 8mg/kg

Plus arsenic –naturally occurring

1884

1952

1964

• Where did it come from?• Anecdotal evidence of a

tannery• Further investigation• 15 further trial pits• 32 soil samples• Mercury 2.3mg/kg to

960mg/kg• Highly leachable• Geology – Made ground

over Northampton Sand and Ironstone Formation

• Mercury found to depths of 2m

Site history• Tannery started between 1884 and

1900• Closed in 1957• Sold in 1965 and used as a garage• 2000 sold for housing

Leather finishing• Tanned leather can be dry and hard• Casein emulsion used to make leather supple and fix the

dyes• Milk based casein has mercuric chloride added to it• Acts as a bactericide• Prevents the casein going off• Usage largely finished by the 1950s

What is casein?• Principle protein found in cows milk as a suspension of casein

micelles• Family of phosphoproteins• Gives milk the white colour• Cheese is the coagulation of casein using rennet• Used in processed food products• Casein based glues used in woodworking and aircraft

manufacture• Casein glue used to coat transformer board• Leather finishing

What next – risk assessment• Inorganic mercury• SNIFFER assessment gave SSAC of 20mg/kg• Installation of boreholes• Mercury in groundwater 83ug/l in borehole and well• Lots of discussion about compliance point• Source removed• Remediation surface strip • Clay capping layer and topsoil

Digging out hotspot

Hotspot reinstated

Why Part IIA?• Missed section of land at back of site outside footprint of the

tannery had elevated levels of mercury max 50mg/kg at near surface

• If mercury found here could it be in other adjoining properties around the tannery/garage

11 – 116mg/kg

0.25 – 5.9mg/kg

Part IIA investigation• 12 properties investigated• Criteria within 20 metres of site boundary• Special site based on the presence of mercury on the Northampton

Sand and Ironstone formation • Investigation undertaken by the Environment Agency

Museum of Leathercraft• Kelly’s Directory 1893 list a John Lee & Son trading in the

village• In the Welland list no mention of this company on either the

1849 or 1874 lists• In 1915 company name changed to John Lee & Son

(Grantham) Ltd• Up to 1930s traded as furriers, hide and skin merchants• In the late 1930s hatters was added to the list• Possibly closed during war time• Known for tanning rabbit hides• Closed in 1957 possibly due to myxomatosis in rabbits

As Mad as a Hatter!• Listed as furriers up to 1930s• Late 1930s company listed as hatters• Fur from small animals used to make felt for hat

making• Suggested they specialised in treating rabbit

hides

Carroting?• Nothing to do with the vegetable!• Rabbit skins rinsed in a heated solution of

mercuric nitrate or brushed onto the pelt• Pelts dried in an over or outside on racks• Turned the rabbit skins a carrot colour• Fur separated from the pelt put onto a cone

shaped colander and treated with hot water to consolidate

• Banned in US in 1941 not because of health risks but that mercury fulminate was needed to make detonators from WWII

• Banned in UK by 1941

Part IIA Investigation• Special site • The Contaminated Land (England) Regulations 2000• Environment Agency took on investigation• WHY

– Certain industries such as oil refining, explosives manufacture– Underground strata listed in Schedule 1 of the regulations– Northampton Sand and Ironstone Formation– Families or groups of substances listed in Schedule 1 of the

regulations– Mercury and its compounds

Part IIA Investigation• Investigated 12 residential properties• Criteria within 20 metres of the boundary of the tannery• Communication strategy• Involved all partners such as the PCT, HPA, GPs, etc• Consultants engaged by the Environment Agency• Sampling of gardens for all three forms of mercury• Results ranged from 8.41mg/kg to 62.4mg/kg• One garden reported levels of mercury up to 62.4mg/kg

(US95 32.2mg/kg)• SSAC 11.1 – 14.2mg/kg

Further investigation

Further investigation

Voluntary remediation

Human health assessment criteriainorganic mercury

mg/kg• ICRCL 1• SNIFFER SSAC 20• SGV 8• SSAC 11.2 – 14.1• SSAC without home grown produce 51• SGV 170• LQM/CIEH S4UL 40• C4SL ND

THANK YOU FOR LISTENING

Mandy DennisSenior Environmental Protection Officer

01832 742037mdennis@east-northamptonshire.gov.uk

Mercury – a Part IIa investigationAn unlikely mix!Section 78A – Part IIA of the Environmental Protection Act 1990What is contaminated land?Slide Number 5Planning and land affected by contaminationMercury can be highly toxicAlways expect the unexpected!1884�1952�1964�?Site historyLeather finishingWhat is casein?What next – risk assessmentDigging out hotspotHotspot reinstatedWhy Part IIA?Part IIA investigation�Museum of LeathercraftAs Mad as a Hatter!�Carroting?�Part IIA InvestigationPart IIA InvestigationFurther investigationFurther investigationVoluntary remediationHuman health assessment criteria�inorganic mercury�THANK YOU FOR LISTENING