Yes was commissioned to carry out a detailed quantitative contamination risk assessment to fulfil planning at a site known as Mullion Garage in Mullion. The site was a former petrol filling station, and the owner wished to construct a new residential dwelling with soft garden areas.
YES carried out a site investigation which comprised sampling of four former fuel tank voids. During the site investigation, the Engineer noted that there was a strong hydrocarbon odour.
The sampled soil was tested for lead and hydrocarbons, and this testing did not identify any significant fuel contamination on site. Despite this, due to the previous land use as a petrol filling station, the below-ground tanks and the strong odour during the site investigation, a risk to human health could be ruled out and remedial measures were considered necessary.
Hydrocarbon-resistant concrete was recommended for the proposed foundations and barrier pipework (instead of the standard blue PVC pipe) was recommended for the new water supply. It was recommended that a vented floor void be paired with a hydrocarbon membrane across all indoor areas to mitigate the risk of any potential vapour ingress.
YES concluded that contaminated soil was able to be used on-site within hardstanding areas. Underneath soft garden areas, contaminated soil needed to be removed and disposed of at a suitable landfill facility. Garden areas required a semipermeable membrane and a covering with 600mm of clean certified topsoil.
The construction of the new residential dwelling is almost complete. The YES team is looking forward to going back as part of the Validation visit.
Check back to see some completion photographs in the near future!