East Midlands summary results

East Midlands Province

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.

• 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.

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.

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

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.

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.

Contact

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