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Senior Activation Manager - Parklands & Venues
Lee Valley Regional Park Authority
Myddelton House, Bulls Cross, Enfield, Middlesex, EN2 9HG
October 2, 2012
| Ph Values of the ground make-up | |||||
| Lowest | Low | Medium | High | Highest | |
| Existing subsoil | 7.7 | 8.3 | 9.6 | 10.8 | 11.1 |
| Type 6F2 | 10 | 10.3 | 10.4 | 10.5 | 10.6 |
| Type 1 | 8.5 | 11.2 | 12 | ||
| Existing Top Soil | 6.6 | 6.7 | 7.1 | 7.2 | 7.4 |
| Imported Top Soil | 8.1 | ||||
| The Ph Values for the Type 1 greyed out on the above table are test results from the stockpiled material at source (Ph11.2 & 12), whereas the actual material on site we tested has a much lower Ph of 8.5. |
| Similarly, the imported topsoil Ph value is derived from a test of the stockpile at source in Rainham. At Ph 8.1 this is considered suitable for general landscaping. |
| In any event the material we have imported for the subsoil level shows Ph values within the range of the existing subsoil material. Although the 6F2 range is much tighter (around 10) and falls between the medium and high Ph values for the existing subsoil, but is not higher than the highest Ph value of the existing material.
(NOTE: See LBWF planning committee report for discussion of PH issue.) |
| We have previously consulted with STRI regarding the effect of Ph in the fill material and they do not consider it to be an issue affecting the growth of the turf or plants - as this material is below the geotextile membrane. |
| Atkins have already commented on the test results which "do not appear to represent an unacceptable risk to either human health or controlled waters". |
From: Richard Harkinson
Subject: Re: [saveleytonmarsh] Fwd: Ph Values of the ground make up
Date: 3 October 2012 09:55:06 BST
To: saveleytonmarsh@yahoogroups.co.uk
Hi Abi
I found some peer reviewed research which found conclusively that groundwater at pH 11 goes through HDPE liners [and other materials]. I was working on alumina waste containment two years ago [the red mud spill in Hungary]. The lead researcher was on sabbatical and difficult to contact. I am almost hopelessly busy but will try to find it.
I know the reason they specify pH neutral to high, so as to prevent acidic mobilisation of heavy metals generally and aluminium into water courses, but the specified range is far too wide and has its own specific risks: alkaline water mobilises aluminium into water courses just as effectively, and UK is in advance ob EU on regulating it.. Aluminium kills fish at very low doses.
Is it now laid? layed? How near to the river?
Was any contact made with EA and with FOE?
Richard