Having discovered pollutant/contaminant linkages within your site, you implemented a system to sever those that were proven to exist. This Remediation Strategy is only as good as its implementation, and it requires Validation and Verification.

Validation is the process where evidence is gathered to prove the remediation has been correctly implemented and works. This Validation then verifies the risk has been reduced and that the remediation objectives and criteria have been met.

Verification needs to be based on a quantitative assessment of the remediation performance using the lines of evidence approach as set out in your Verification Plan which forms part of the Remediation Strategy.

If your planning authority (council) cannot see, via a verification/validation report, that the remediation has been undertaken with care and with attention to detail, then it will not sign off your development.

Below are the errors that Ground & Water most often notes when we have tried to validate/verify sites for developers.

The top errors during validation:

• Cross-contamination of Waste/Topsoil stockpiles often due to stray dumper loads.

This can be prevented by good material management. What we don’t want to see is materials being removed due to being contaminated, mixing with material which is destined to be used in gardens. The last thing you need are fibres of Asbestos in the Topsoil.

• Lack of evidence of soil movements… Tracking what materials go off site. 

It is the landowner/developer’s responsibility to ensure materials/waste that are removed from site are disposed of appropriately. Therefore, councils will want to see that this has occurred. They mainly do this by consignments notes, showing where waste has been produced and where its gone. Councils will want to see that the number of notes equals the anticipated material to be removed… Be careful, this is a frequent pitfall! KEEP YOUR CONSIGNMENT NOTES.

• Soil settlement – Insufficient thickness of capping materials.

Over time subsoil/topsoil settles. A subsoil/topsoil capping validated immediately after placement may be 600mm deep, but in a month its likely to be 500 – 550mm. This needs to be taken into account when undertaking works.

• Insufficient time to conduct a proper Capping Validation.

A typical validation timeline can be seen below. Laboratory testing of imported Topsoil is usually on five working day turnaround. But we need time to get onsite, sample and analyse the results. Lab testing can be undertaken on a three-day basis, but it s more expensive. The key is to allow enough time for us to carry out the validation. Please don’t phone us a few days before CML/hand-over, expecting a certificate to magically appear. It’s a bit tricky carrying out validation with residents in their houses.

• Unexpected contamination.

Sometimes sites can throw you a curved ball… On one site we worked on, a hotspot of high metallic contamination was identified during an excavation which gave workers nearby a nasty rash. It can happen!

The council will want to be sure that no unexpected contamination was noted during site works/foundation excavations. Generally, a statement from the development/groundworker that nothing was found, outside what was known, is sufficient. However, if the council thinks there are gaps in this, it may start to ask for more. To prepare for this, you should collate evidence as the build progresses. Take lots of photos of foundation excavations and in-ground trenches. You can also pay for visits at certain times during the development process.

• Poor quality Topsoil.

The last thing you want is rubbish topsoil being sent to your site, which is as contaminated as the material you have excavated and sent to Waste. The composition of any stockpiled or imported Topsoil must comply with BS3882:2015 standards and is subject to specialist testing to validate the material’s fertility, chemical composition, strength and classification. Ground & Water will help you find a reputable source, provide independent verification and issue appropriate certifications of compliance. You can read more about this HERE.

The Ground & Water Difference

The journey from a Phase 1 Contaminated Land Risk Assessment (Desk Study) to implementing a Remediation Strategy, if pollutant/contaminant linkages are found to be present on your site, requires a considerable investment in time and money. All this work and investment can fall at the final hurdle if the council rejects the all-important Validation/Verification report, meaning the remedial work may have to be re-done.

Ground & Water will work with you to help you avoid the pitfalls and ensure that your development gets the all-important sign-off.