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ICRCL TENTATIVE "TRIGGER CONCENTRATIONS" FOR SELECTED INORGANIC CONTAMINANTS

CONDITIONS

1. This Table is invalid if reproduced without the conditions and footnotes.

2. All values are for concentrations determined on "spot" samples based on an adequate site investigation carried out prior to development. They do not apply to analysis of averaged, bulked or composited samples, nor to sites which have already been developed. All proposed values are tentative.

3. The lower values in Group A are similar to the limits for metal content of sewage sludge applied to agricultural land. The values in Group B are those above which phytotoxicity is possible.

4. If all sample values are below the threshold concentrations then the site may be regarded as uncontaminated as far as the hazards from these contaminants are concerned and development may proceed. Above these concentrations, remedial action may be needed, especially if the contamination is still continuing. Above the action concentration, remedial action will be required or the form of development changed.

Contaminants Planned Uses

Trigger Concentrations
(mg/kg air-dried soil)
   

Threshold

Action
Group A: Contaminants which
may pose hazards to health		      
Arsenic


Cadmium


Chromium (hexavalent)(1)


Chromium (total)


Lead


Mercury


Selenium		 Domestic gardens, allotments.
Parks, playing fields, open space.

Domestic gardens, allotments.
Parks, playing fields, open space.

Domestic gardens, allotments.
Parks, playing fields, open space.

Domestic gardens, allotments.
Parks, playing fields, open space.

Domestic gardens, allotments.
Parks, playing fields, open space.

Domestic gardens, allotments.
Parks, playing fields, open space.

Domestic gardens, allotments.
Parks, playing fields, open space.		 10
40

3
15

25


600
1,000

500
2,000

1
20

3
6

*
*

*
*

*


*
*

*
*

*
*

*
*
Group B: Contaminants which are
phytotoxic but not normally hazards to health		      
Boron (water-soluble) (3)


Copper (4, 5)


Nickel (4, 5)


Zinc (4, 5)

 Any uses where plants are to be grown (2, 6)

Any uses where plants are to be grown (2, 6)

Any uses where plants are to be grown (2, 6)

Any uses where plants are to be grown (2, 6)

 3


130


70


300

*


*


*


*


NOTES:
* Action concentration will be specified in the next edition of ICRCL 59/83 - [suggested levels below]

1. Soluble hexavalent Cr extracted by 0.1M HC1 at 37EC; solution adjusted to pH 1.0 if alkaline substances present.

2. The soil pH value is assumed to be about 6.5 and should be maintained at this value. If the pH falls, the toxic effects and the uptake of these elements will be increased.

3. Determined by standard ADAS method (soluble in hot water).

4. Total concentration (extractable by HN3/HC104).

5. The phytotoxic effects of copper, nickel and zinc may be addictive. The trigger values given here are those applicable to the ‘worst-case’: phytotoxic effects may occur at these concentrations in acid, sandy soils. In neutral or alkaline soils phytotoxic effects are unlikely at these concentrations.

6. Grass is more resistant to phytotoxic effects than are most other plants and its growth may not be adversely affected at these concentrations.

ICRCL TENTATIVE "TRIGGER CONCENTRATIONS" FOR CONTAMINANTS ASSOCIATED WITH FORMER COAL CARBONISATION SITES

CONDITIONS

1. This Table is invalid if reproduced without the conditions and footnotes.

2. All values are for concentrations determined on "spot" samples based on an adequate site investigation carried out prior to development. They do not apply to analysis of averaged, bulked or composited samples, nor to sites which have already been developed.

3. Many of these values are preliminary and will require regular updating. They should not be applied without reference to the current edition of the report "Problems Arising from the Redevelopment of Gas Works and Similar Sites". (1)

4. If all sample values are below the threshold concentrations then the site may be regarded as uncontaminated as far as the hazards from these contaminants are concerned and development may proceed. Above these concentrations, remedial action may be needed, especially if the contamination is still continuing. Above the action concentration, remedial action will be required or the form of development changed.

Contaminants Proposed Uses Trigger Concentration (mg/kg air-dried soil)
   

Threshold

Action
Polyaromatic hydrocarbons (1,2)




Phenols




Free cyanide




Complex cyanides





Thiocyanate (2)

Sulphate






Sulphide

Sulphur

Acidity (pH less than)		 Domestic gardens, allotments,
play areas.

Landscaped areas, buildings,
hard cover.

Domestic gardens, allotments.

Landscaped areas, buildings,
hard cover.

Domestic gardens, allotments, landscaped areas.

Buildings, hard cover.

Domestic gardens, allotments.

Landscaped areas.

Buildings, hard cover.

All proposed uses.

Domestic gardens, allotments, landscaped areas.

Buildings (3).

Hard cover.

All proposed uses.

All proposed uses.

Domestic gardens, allotments, landscaped areas.

Buildings, hard cover.		 50


1,000


5

5


25


100

250

250

250

50

2,000


2,000 (3)

2,000

250

5,000

pH5


NL		 500


10,000


200

1,000


500


500

1,000

5,000

NL

NL

10,000


50,000(3)

NL

1,000

20,000

pH3


L

 

NOTES:
NL: No limit set as the contaminant does not pose a particular hazard for this use.

(1): Used here as a marker for coal tar, for analytical reasons. See "Problems Arising from the Redevelopment of Gas Works and Similar Sites" Annex 1. (1).

(2): See "Problems Arising from the Redevelopment of Gas Works and Similar Sites" for details of analytical methods. (1).

(3): See also BRE Digest 250: Concrete in sulphate-bearing soils and ground water. (4).

POSSIBLE ACTION VALUES FOR ICRCL METALS

The following are possible action values* for the ICRCL metals in high risk use classes. These are based on the mean of similar values from several other countries. They are merely examples and actual concentrations used in practice should be based on site specific circumstances taking into consideration soil type, proposed end use and sensitivity of recognised targets.

 

Contaminant

Value* mg/kg

Arsenic

69

Cadmium

15

Chromium

664

Lead

813

Mercury

10

Selenium

17

Boron

100

Copper

423

Nickel

376

Zinc

1665

 

* All the above values have been taken from the book:

22 Soil Contaminant Profiles - Properties, Source, Abundance and
Importance in Contaminated Land Investigations

The book looks at 22 elemental contaminants and describes:

* Their properties
* Use in industry
* Natural abundance
* Levels in different soils
* Principal sources of pollution
* Biological significance
* Considers screening and action levels from over 20 other sources, and
* Rates their importance on a scale of 1-5 in contaminated land investigations

It is available from Zero Environment Ltd price £30 + VAT + P&P

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FIGURE 1
 INTERPRETATION OF ICRCL "TRIGGER CONCENTRATIONS"


 


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