Surface water infiltration value ahead of PP application ??

[pipedream]

 

I am about to apply for planning for demolition of the bungalow, we have been living in to replace with a structure with 35% larger footprint.

Since April 2019 the Greater London councils have made it mandatory to include a suds proforma (attached) for all new build/extensions (with increase in footprint) applications. 
I can appreciate the intention, but details sought feels unreasonable at this stage. 

 

I think, I can fill the other fields and can do a percolation test if needed, but no idea how section 2a below can be filled with out paying out for drainage engineer/survey..

2a. Infiltration Feasibility                                        
-Superficial geology classification                                        
-Bedrock geology classification                                        
-Site infiltration rate    in m/s            
-Depth to groundwater level in m below ground level            
-Is infiltration feasible?                                        

Anyone else had to deal with this before ? Any other pointers will be much appreciated.
 

enfield_suds_proforma_0 (1).xlsx

Edited September 24, 2021 by pipedream

[Ferdinand]

I love the "site infiltration rate" in m/s.

 

Presumably quite a lot if it is an aircraft crashing or a meteorite.

 

?

 

(An intelligent person with an answer will be along in a minute)

[Mr Punter]

I have not done one of these.  It may be useful to look at other approved planning applications and see what information they have included.

[WWilts]

We faced a similar requirement. British Geological Survey provided a report centred on the site location. Sufficed. Cost about £20 iirc

[pipedream]

1 hour ago, Mr Punter said:

I have not done one of these.  It may be useful to look at other approved planning applications and see what information they have included.

I managed to locate one relatively quickly but a detailed drainage strategy report (££) went with it  . I am  searching for more.

 

1 hour ago, WWilts said:

We faced a similar requirement. British Geological Survey provided a report centred on the site location. Sufficed. Cost about £20 iirc

 Great thanks ! .I checked the website and have a few Qs, I will PM you ,if you don't mind.

Edited September 24, 2021 by pipedream

[WWilts]

BGS info actually cost £84, just checked. Included
24 maps in four thematic sections:
o Very significant constraints. Maps highlight areas where infiltration may
result in adverse impacts due to factors including: ground instability
(soluble rocks, non-coal shallow mining and landslide hazards); persistent
shallow groundwater, or the presence of made ground, which may
represent a ground stability or contamination hazard.
o Drainage potential. Maps indicate the drainage potential of the ground, by
considering subsurface permeability, depth to groundwater and the presence
of floodplain deposits.
o Ground stability. Maps indicate the presence of hazards that have the
potential to cause ground instability resulting in damage to some buildings
and structures, if water is infiltrated to the ground.
o Groundwater protection. Maps provide key indicators to help determine
whether the groundwater may be susceptible to deterioration in quality as a
result of infiltration.

[pipedream]

thanks got hold of a sample report , very detailed indeed.

https://www.molevalley.gov.uk/CausewayDocList/DocServlet?ref=MO/2016/1566&docid=653944

 

still missing the 

8 hours ago, pipedream said:

-Site infiltration rate    in m/s     

 

any idea how to deduce it perhaps?