East Midlands summary results

Regional summary

In the East Midlands Province, 93 sites have been sampled, in the three main aquifers: the Lincolnshire Limestone, Permo-Triassic sandstone and Chalk.

Geology of the East Midlands ProvinceGeology of the East Midlands Province The Lincolnshire Limestone is a hard, fractured aquifer and groundwater flows almost entirely by fracture flow along bedding planes. Abstraction for public water supply takes place mainly in the confined region, where the groundwater is artesian. It has a maximum thickness of 40 m in south Lincolnshire. Permo-Triassic sandstone is the UK's second most important aquifer and has a high porosity, which means the majority of flow occurs through the pore spaces in the rock. The water from this aquifer is generally of good quality and is exploited for a wide range of uses. It has a maximum thickness of 180 m in Yorkshire. The Chalk aquifer of Yorkshire and Humberside is a productive fractured aquifer, which outcrops in the Yorkshire Wolds. It has a total thickness of 430 m. A large proportion of public water supply in the region is derived from this aquifer. There are a number of shale units present in this area, including the Kimmeridge, Ampthill, Lias, Bowland and Craven Groups. The Bowland and Craven Groups are reported to have the potential to form a shale gas resource (Andrews, 2013) in addition to the Kimmeridge Clay, as reported in DECC (2012) 3.7 KB pdf. The Lias, Kellaways, Oxford Clay and Osgodby Formation are thought to be too immature for shale gas.

Methane in UK groundwater results These summaries are based on the results collected from single visits to each site for the purpose of the methane baseline project. The data are summarised for the Midlands and Yorkshire as a whole, and also for individual aquifers, where enough data are available.

The blue boxes highlight where summary data are available for baseline groundwater quality in the different aquifers present in this region, and link to the summaries for each region.

Methane concentrations chart for the Midlands and Yorkshire Area Concentration (mg/l) Number of samples Minimum Median Maximum East Midlands Province <0.00005 0.0009 1.32 93 Lincolnshire Limestone 0.00005 0.0026 0.032 13 Sherwood Sandstone <0.00005 0.0005 0.465 34 Lincolnshire Chalk 0.00007 0.0009 0.0047 23

Methane samples and concentrations in the East Midlands Province. Note: values less than the analytical detection limit have been converted to half the detection limit for the purposes of this statistical summary and graph, but the relevant detection limit is quoted in the table above. Baseline groundwater quality data in the Permo-Triassic sandstone A summary of the baseline quality of groundwater in the Permo-Triassic sandstone is below. These data were collected as part of a collaborative project between BGS and the Environment Agency to investigate the baseline quality of groundwater in major UK aquifers. The UK baseline study results page provides downloads of all the reports produced by the project.

Box and whiskers plot Analysis Concentration (mg/l) Number of samples Minimum Median Maximum Ca 55.3 140 556 43 Mg 20.6 34.7 133 43 Na 7 35.3 402 43 K <0.6 4 13.5 43 Cl 12.5 36.6 307 43 SO4 6.1 170 1760 43 HCO3 234 333 498 43 NO3.N <0.0025 0.053 41.1 43

Baseline quality data for the Permo-Triassic sandstone in the Midlands The quality of groundwater in the Permo-Triassics sandstone is determined by natural reactions between rainwater and the bedrock, which creates a variable baseline. Nitrate (NO3.N) and chloride (Cl) are elevated due to agricultural and industrial practices, and the groundwater can have a higher salinity in the confined part of the aquifer.

Baseline groundwater quality data in the Lincolnshire Limestone A summary of the baseline quality of groundwater in the Lincolnshire Limestone is below. These data were collected as part of a collaborative project between BGS and the Environment Agency to investigate the baseline quality of groundwater in major UK aquifers. The UK baseline study results page provides downloads of all the reports produced by the project.

Box and whiskers plot Analysis Concentration (mg/l) Number of samples Minimum Median Maximum Ca 1.53 144 203 62 Mg 0.5 7.3 75.5 62 Na 9 23.7 4030 62 K <1 2.37 71.5 62 Cl 21 57.1 6250 62 SO4 <0.2 110 200 62 HCO3 251 294 606 23 NO3.N <0.003 4.7 20.7 37

Baseline quality data for the Lincolnshire Limestone in the Midlands In the Lincolnshire Limestone, the quality of the water varies considerably between the unconfined and confined regions. In the recharge areas, the water is fresh, although impacted by agricultural pollution, whereas the confined groundwaters are old and reducing, and can be of poor quality.

Baseline groundwater quality data in the Chalk A summary of the baseline quality of groundwater in the Chalk is below. These data were collected as part of a collaborative project between BGS and the Environment Agency to investigate the baseline quality of groundwater in major UK aquifers. The UK baseline study results page provides downloads of all the reports produced by the project.

Box and whiskers plot Analysis Concentration (mg/l) Number of samples Minimum Median Maximum Ca 60.8 105 252 149 Mg 0.83 3.43 626 149 Na 4.7 11.8 4910 149 K 0.26 1.42 155 148 Cl 11.2 27.9 8890 149 SO4 <5 29.7 1290 149 HCO3 120 241 464 148 NO3.N <0.2 8.01 33.2 148

Baseline quality data for the Chalk in the Midlands The quality of groundwater in the Chalk aquifer of Yorkshire and Humberside is very variable due to a number of geochemical processes. The Chalk groundwater is generally hard and the unconfined areas have been impacted by seawater intrusion and human activities, such as pollution from agriculture. Groundwater in the confined and semi-confined sections of the aquifer has some protection from the effects of pollution.

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