OR/16/010 Using the data

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Dearden, R. 2016. User guide for the infiltration SuDS map: summary. British Geological Survey Internal Report, OR/16/010.

Setting up the GIS

To ensure that the dataset is used as designed, follow the proceedings steps to set-up the map:

a) Make sure the required data layers, as shown below, are present.
  • Infiltration_constraints_summary
  • Drainage_summary
  • Ground_stability_summary
  • Groundwater_protection_summary

If you have licensed data as a MapInfo .tab file and the infiltration constraint file is missing, this may be because the chosen area is not affected by any constraints (i.e. there is no data). MapInfo cannot create a file without data, conversely, ArcGIS shape files can be created regardless and so there should not be any .shp files missing.

b) Import the data layers into the GIS software such that they appear in the order shown in Figure 2.

If you’re using ESRI ArcGIS, the GIS can be set-up simply by using the single group layer file called Infiltration_SuDS_Map_Summary.lyr. Either import this into an existing ArcGIS document, or double click on the file to open a new GIS document.

Alternatively, import the layer files (.lyr) from the Severe_Constraints, Drain, Stability, and Water_Quality folders provided. By using layer files, the polygons will be imported with the correct symbology. The map should be coloured via the short description attribute as shown in Table 8, such that it mirrors that shown in Figure 5 for the Drainage Summary layer.

Table 8 RGB colours to be assigned to score classes.
Datasets

Score

1

2

3

4

Infiltration Constraints Summary R: 156
G: 156
B: 156
Drainage Summary R: 235
G: 240
B: 255 		R: 199
G: 209
B: 255 		R: 156
G: 156
B: 227 		R: 156
G: 156
B: 156
Ground Stability Summary R: R: 229
G: 245
B: 179 		R: R: 198
G: 222
B: 133 		R: R: 145
G: 163
B: 97 		R: 156
G: 156
B: 156
Groundwater Protection Summary R: R: 245
G: 220
B: 229 		R: R: 217
G: 169
B: 187 		R: R: 179
G: 117
B: 143 		R: 156
G: 156
B: 156
c) We recommend setting the polygon transparency to 30 per cent.

If you need support setting up the GIS, please contact digitaldata@bgs.ac.uk.

Figure 5 Infiltration SuDS map loaded into ArcGIS, showing legend colours.

How to use the data for a site assessment

This section provides advice on how to use the dataset. Turn on each dataset individually, so that only one dataset and the topography layer is visible at any one time.

a) Load the Infiltration SuDS Map dataset into the preferred GIS software as described in Setting up the GIS.
b) Pan to, or locate by coordinates, the location of interest
c) Turn on the Infiltration constraints summary layer
If an ‘infiltration constraints’ polygon is identified at the site it indicates that there is potential for a hazard if water is infiltrated to the ground. In such areas, infiltration SuDS should only be installed if the potential for, or the consequences of, the constraint are considered not to be significant.
d) Turn on the Drainage Summary layer to obtain a rapid assessment of the drainage potential of the ground. At the location of interest, use the cursor in ‘Identify’ mode to determine the attributes of the polygon overlaying the site. The following attributes may be encountered.
  • Highly compatible for infiltration SuDS.
  • Probably compatible for infiltration SuDS.
  • Opportunities for bespoke infiltration SuDS.
  • Very significant constraints are identified.
e) Turn on the ground stability summary layer to obtain a spatial assessment of the expected stability of the subsurface should water be infiltrated. At the location of interest, use the cursor in ‘Identify’ mode to determine the attributes of the polygon overlaying the site. The following attributes may be encountered:
  • Geohazard unlikely.
  • Potential for geohazard.
  • Significant potential for geohazard.
  • Very significant constraints are identified.
f) Turn on the groundwater protection summary layer to obtain a rapid assessment of factors that may influence infiltration SuDS design with respect to protecting groundwater quality. At the location of interest, use the cursor in ‘Identify’ mode to determine the attributes of the polygon overlaying the site. The following attributes may be encountered.
  • Low susceptibility.
  • Moderate susceptibility.
  • Considerable susceptibility.
  • Very significant constraints are indicated.

Worked examples

Table 9 summarises data obtained from the Infiltration SuDS Map: Summary for three locations; A, B and C, each of which represents a location where an infiltration system has been installed. The data does not state which type of infiltration system is appropriate, or, in any way, offer advice on appropriate infiltration systems, but does allow you to develop a conceptual model of the subsurface geology as shown in Figure 9.

Table 9 Data for three locations, A, B and C where infiltration devices (soakaway, permeable pavement and infiltration basins respectively) have been installed. All red text derived from Infiltration SuDS Map: Summary.
Data layer Location A Location B Location C
System installed Soakaways Permeable pavements Infiltration basin
Infiltration constraints summary Null Null Null
Drainage summary Highly compatible for infiltration SuDS Probably compatible for infiltration SuDS Opportunities for bespoke infiltration SuDS
Ground stability summary Potential for geohazard Significant potential for geohazard Potential for geohazard
Groundwater protection summary Low susceptibility Low susceptibility Moderate susceptibility
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