OR/15/065 Appendix 5 - Sulfate/sulfide potential classification descriptions

Entwisle, D, Lee, K A, and Lawley, R S. 2015. User guide for ‘BGS Civils’ - a suite of engineering properties datasets. British Geological Survey Internal Report, OR/15/065.

Primary classification of sulfate/sulfide as used in the GIS

Primary Class	Description
0	Sulfate/sulfide not generally present.
1	Primary calcium sulfate present.
2	Iron sulfide and calcium carbonate present. The iron sulfide will or might oxidise to form sulfuric acid and react with calcium carbonate to form secondary gypsum.
3	Units that contain sulfides that might oxidise to form acid ground conditions.
4	Mixed, contains beds with iron pyrites and calcium carbonate and beds with iron pyrites and little or no calcium carbonate.
5	Contains beds of anhydrite or gypsum, and sulfides that might oxidise and react with calcium carbonate.
6	Unknown, lithologies not known.
7	Areas of mapped water – not applicable.

Secondary classification of sulfate/sulfide as used in the GIS

SUL_CLSS	SUL_DESC
0A	Sulfate or sulfide that will oxidise are not normally present.
1A	Major sulfate bed. The sulfate might be leached from the near-surface zone, the thickness depends on local conditions.
1B	Sulfate common throughout as beds, nodules and veins. The sulfate might be leached from the near-surface zone, the thickness depends on local conditions.
1C	Sulfate beds, nodules and veins are present at certain levels. The sulfate might be leached from the near-surface zone; the thickness depends on local conditions.
1D	Sulfate beds, veins and nodules are present locally at certain levels. The sulfate might be leached from the near-surface zone; the thickness depends on local conditions.
1E	Minor sulfate: in beds present locally at certain levels or as dispersed nodules. The sulfate might be leached in the near surface zone; the thickness depends on local conditions.
2A	Sulfide oxidises in weathering zone or when disturbed and reacts with calcium carbonate to form secondary gypsum.
2B	Sulfide likely to oxidise in weathering zone or when disturbed and reacts with calcium carbonate to form secondary gypsum.
2C	Sulfide might be present and oxidise in weathering zone or when disturbed and react with calcium carbonate to form secondary gypsum.
2D	Sulfide and calcium carbonate might be present, unlikely to form secondary gypsum unless reworked.
2E	Sulfide and calcium carbonate might be present, unlikely to form secondary gypsum.
3A	Sulfide likely to oxidise in weathering zone or when disturbed to form acidic conditions.
3B	Sulfide likely to oxidise when disturbed to form acidic conditions.
3C	Sulfide present locally and might oxidise when disturbed to form acidic conditions.
3D	Sulfide might be present in some beds that will only oxidise when disturbed to form acidic conditions.
3E	Sulfide might be locally present in some beds and might oxidize when disturbed to produce acidic conditions.
4A	Mixed lithologies, with beds containing sulfide, sometimes with calcium carbonate. Sulfide oxidises when weathered.
4B	Mixed lithologies, with beds containing sulfide, sometimes with calcium carbonate. Sulfate might oxidize under some conditions (e.g. reworking).
4C	Mixed lithologies, sulfide beds occasionally present sometimes with calcium carbonate. Sulfide might oxidize under some conditions (e.g. reworking).
5A	Minor sulfate and sulfide and calcium carbonate beds present locally. Sulfate might be leached in the near surface zone, depth depends on zone local conditions. Sulfide might oxidise.
5B	Contains minor beds of sulfate and sulfides that might oxidise under unusual conditions such as mining operations or reworking.
6	Sulfate/sulfide content unknown (geology unknown).
7	No hazard (water body).