Former Monsanto Chemical Tip

Wrexham County Borough Council

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Objectives

Obtain information to assess whether there is a significant possibility of significant harm

Obtain information to assess pollution of controlled waters

Should the land be determined as "Contaminated Land" under Part IIA of Environmental Protection Act 1990?

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Pollutant Linkage

A Pollutant Linkage comprises a Source – Pathway – Receptor

The suspected Pollutant Linkages are combined to form a Conceptual Model for the site

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Inspection Process

Desk Study

Visual Inspection

Intrusive Site Investigation

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Desk Study Reviewed previous investigations and information on the

site

Identified waste materials had been tipped on the west of site which contained various organic chemicals

Previous investigations identified contamination in seepages on the railway cutting derived from perched water

Mine shafts – pathway / location of tipping?

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Conceptual Model

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Investigation

Sampling– Source materials within the tipped area – Trial Pits / Window

Samples– Receptor / Pathway sampling – Soil Vapour, Boreholes to the east

of the site, Seepages, Streams

Risk Assessment– Frameworks set out by Defra / Environment Agency

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Exploratory Hole Locations

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Surface Water Sample Locations

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Conclusions Human Health

– WCBC have taken measures to secure the site Considered no plausible dermal contact / ingestion pathway for

chemicals that are not significantly volatile

– Receptors considered to be users of adjacent sites

– Also Volatile Organic Compounds (e.g. naphthalene, benzene) Inhalation risk? Not all chemicals could be assessed because of a lack of toxicity data /

chemical behaviour data For volatile organic chemicals that could be assessed it is not

considered that there is significant possibility of significant harm arising from the site (as defined by the current fence line) on the basis of the data and conceptual model,

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Conclusions (continued)

Controlled Waters– Not all data received at the time of the assessment– Groundwater pollution within tip

(metals, sulphate, phenol, naphthalene, benzothiophene plus additional Semi-Volatile Organic Compounds)

– Evidence of degradation over time and distance– Organic contaminants generally not observed in the Coal

Measures or seepages – if present, present at low concentrations– No significant pollution of streams identified

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Other Issues

Limitations – Limited data– Uncertain sources – varied materials within the tip– Assessment on current condition – change with time e.g. drums

corroding?– Mine workings acting as a pathway?

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Other Issues

Further Actions– Vapour monitoring– Water monitoring – Confirm that fence is adequate to control exposure

– survey– sample– monitor

– If opening the railway as a footpath is considered further sampling and assessment will be required