Coralline Crag Formation
London Clay Formation (Thames Group)
Harwich Formation
Calcrenite (sand) Clay Clay
Lambeth Group and Thanet Sand Formation Clay, sand and silt
Chalk Formation Chalk
Secondary A Aquifer Unproductive Strata Unproductive Strata Secondary A aquifer Principal Aquifer
55.
The vulnerability of the Principal Aquifer to pollution is at its lowest where it is protected by the overlying (unproductive) London Clay Formation or Harwich Formation. Where Secondary A Aquifers directly overlie the Principal Aquifer (i.e. Crag Aquifers or Lambeth Group and Thanet Sand Formations), these are assumed to slow down but not prevent the transmission of contaminants and are considered to be in hydraulic connectivity with the Principal Aquifer.
56. Where the Chalk outcrops with no superficial or other bedrock deposits overlying, especially in the area around the River Gipping valley, Claydon, the risk to the Principal Aquifer is at its greatest.
21.5.1.3 Groundwater Quality 57.
The onshore electrical transmission works extends through two groundwater bodies as delineated as part of the Water Framework Directive (WFD), namely the Waveney and East Suffolk Chalk and Crag water body and the Felixstowe Peninsula Crag and Chalk water body. River Basin Management Plans for groundwater1 within the both groundwater bodies describes the ‘current quantitative quality’ of groundwater below the onshore electrical transmission works as ‘Good’. Current chemical quality is described as ‘Poor’ on the basis of failure of the general chemical assessment. This test is based on a review of the Environment Agency’s groundwater chemical data to determine whether there is a widespread exceedence in a range of hazardous substances and non-hazardous pollutants.
58.
With regards to the groundwater Drinking Water Protected Areas (DrWPA) as defined under the WFD, the groundwater bodies beneath the onshore electrical transmission works have been identified by the Environment Agency as being either in a ‘Not at Risk’ zone or a ‘Probably Not at Risk’ zone, refer to Figure 21.2. Drinking
1
http://maps.environment-agency.gov.uk/wiyby viewed on 12 August 2013
Preliminary Environmental Information May 2014
East Anglia THREE Offshore Windfarm
Chapter 21 Water Resource and Flood Risk Page 23
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58