Erection of a Dwelling, Wallace Lane, Forton, Preston, Lancashire, PR3

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 had not been developed. Street level imagery confirmed the site formed part of the garden of the adjoining dwelling.

A garage was noted 70m north of the site as well as a disused quarry 190m south, which was in-filled by the 1970 map.

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

The published geological maps identified the site as being underlain by Devensian iIll which in turn were underlain by Crossdale Mudstone. As no publicly available boreholes for the areas were available from the BGS no further information in ground conditions could be obtained.

Data provided by regulatory bodies confirmed the presence of a pit to the south of the site.

On completion of the desk based research a site reconnaissance visit was undertaken, this confirmed the site comprised of an overgrown field. As part of the walkover survey a single hand held trial pits was excavated to a depth of 0.3mbgl, no evidence of made ground was recorded.

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 in-filled quarry posed a potential risk to the site. The report proposed eith ground gas monitoring or the incorporation as precautionary gas protection measures based on a reasonable worst case scenario.

The report was submitted (15/00269/DIS) to partly discharge the contaminated land planning condition and the proposals accepted.