DEMETER ENVIRONMENTAL / CASE STUDY

Erection of a Dwelling, Lancaster Road, Out Rawcliffe, Preston, Lancashire, PR3

PROJECT OVERVIEW

Gas protection and validation at Out Rawcliffe

For a proposed dwelling at Out Rawcliffe, Demeter assessed historical uses, regulator information and the potential for gases from underlying peat. The desk study recommended gas protection as an alternative to monitoring for the assessed conditions. The planning condition was partly discharged, with a validation report still required for full discharge. The record does not claim completed validation.

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Given the sensitive nature of the development (residential) and the history of the site a contaminated land planning condition was attached to the decision notice for the proposed development.

The first stage of discharging the condition was to prepare a Phase I desk study report in order to determine if the site has the potential to be impacted by elevated levels of contamination, and to determine the source as well as the likelihood of the risk occurring.

A desk study determines what issues relating to historical contamination may affect the site, this is undertaken by reviewing the site history using a combination of O.S. maps, aerial, plates and street level imagery, a review of data held by regulatory bodies (Environment Agency, local authority, BGS etc.) as well as a site walkover survey.

The history of the site and surrounds were researched using a combination of Ordnance Survey (O.S.) maps, street level imagery and aerial plates, this revealed the site has not been subject to development but formed part of the land associated with Chathill Farm.

The planning history of the site was reviewed as part of the desk based research and the reports associated with the 16 previous application and the subject were located and studied, no salient information was obtained

The published geological maps identified the site as being underlain by peat (potential source oof ground gases) which in turn were underlain by the Sherwood Sandstone Group. As no publicly available boreholes for the areas were available from the BGS no further information ion ground conditions could be obtained.

Data provided by regulatory bodies identified a enforcement actions 4m east of the site, further research revealed this was associated with a maggot farm. Further research was undertaken on the use of the land to the east as a maggot far, this indicated the main by product was ammonia.

On completion of the desk based research a site reconnaissance visit was undertaken, this confirmed the site formed part of a field.

Once the walkover survey was completed a qualitative risk assessment was undertaken on the potential sources of contamination identified in the desk study report in order to determine if any warranted further investigation, this concluded that the underlying peat (naturally occurring) warranted further assessment.

Given that the potential source was naturally occurring, the migration of gases is regarded as negligible and the source was unlikely to generate flows/concentrations above Characteristic Situation2 the incorporation of gas protection measures in lieu of ground gas monitoring was proposed.

The report was submitted to partly discharge the contaminated land planning condition (16/00058/DIS), with the condition being partly discharged with the requirement of a validation report in order to fully discharge the condition.