F1SCHEDULEGroundwater Threshold Values
Sch. Table 1 substituted (20.6.2016) by The Groundwater (Amendment) Regulations (Northern Ireland) 2016 (S.R. 2016/119), regs. 1(1), 5
Parameter | Unit | To examine if groundwater abstraction is causing saline or other intrusions | To examine if groundwater is providing a significant contribution to the failure of the environmental objectives of associated surface water bodies | To examine if the quality of groundwater that is abstracted for potable use is deteriorating, possibly resulting in a need for increased purification | To examine the spatial extent of a groundwater body or group of bodies that are exceeding an EU Standard or threshold value |
|---|---|---|---|---|---|
Ammonium | mg/l | 0.29 | |||
Arsenic | μg/l | 7.5 | |||
Atrazine | μg/l | 0.075 | |||
Cadmium | μg/l | 3.75 | |||
Chloride | mg/l | 25 | |||
Electrical Conductivity | μS/cm | 800 | 1875 | ||
Lead | μg/l | 7.5 | |||
MCPA | μg/l | 0.075 | |||
Mecoprop | μg/l | 0.075 | |||
Mercury | μg/l | 0.75 | |||
Nitrate (as NO3) | mg/l | 37.5 | 37.5 | ||
Nitrite | μg/l | 375 | 375 | ||
Simazine | μg/l | 0.075 | |||
Sulphate | mg/l | 187.5 | |||
Tetrachloroethylene | μg/l | 7.5 | 7.5 | ||
Trichloroethylene | μg/l | 7.5 | 7.5 | ||
Any pollutant in relation to which a surface water environmental standard has been set(1) | 0.5 x (surface water standard divided by dilution factor)(2) | ||||
(1) The surface water environmental standards are set out in Schedule 1 to The Water Framework Directive (Classification, Priority Substances and Shellfish Waters) Regulations (Northern Ireland) 2015(S.R. 2015 No. 351). | |||||
(2) The “dilution factor” is taken to be the fraction of the average annual river flow derived from groundwater inflows. It can be estimated from established hydrological indices such as the baseflow index, or from the ratio of catchment groundwater recharge to effective precipitation. | |||||
Column header | Annual mean nitrate concentration (mg/l NO3) | ||
|---|---|---|---|
Altitude Above Ordnance Datum | |||
Wetland type | up to 175 metres | more than 175 metres | any |
Quaking bog | 18 | 4 | |
Wet dune | 13 | ||
Fen (mesotrophic) and Fen Meadow | 22 | 9 | |
Fen (oligotrophic and wetlands at tufa forming springs) | 20 | 4 | |
Wet grassland | 26 | 9 | |
Wet heath | 13 | 9 | |
Peatbog and woodland on peatbog | 9 | ||
Wetland directly irrigated by spring or seepage | 9 | ||
Swamp (mesotrophic) and reedbed | 22 | ||
Swamp (oligotrophic) | 18 | ||
Wet woodland | 22 | 9 | |
Sch. inserted (31.7.2014) by The Groundwater (Amendment) Regulations (Northern Ireland) 2014 (S.R. 2014/208), regs. 1, 12