Street Works UK Protocol: What to Know Six Months On

SWUK is an Environment Agency approved method designed to meet the law that all excavated waste must be classified under WM3 before it is moved. It is a route to meet the obligation for qualifying utility street works, but not a replacement for the legislation – it aids compliance with laws such as New Roads and Street Works Act 1991 (NRSWA) and the Traffic Management Act 2004 (TMA). It applies to all utilities and contractors undertaking immediate, minor, standard, or some major works that generate excavation waste.

This was a significant shift in compliance expectations as the protocol is a risk-based framework with stricter requirements designed to improve how excavation waste from utility street works is assessed, classified, and managed.

Lab results under SWUK do not classify waste at the point of removal but do verify that the site-based risk assessment classification is accurate – the testing just supports classification. Reactive works cannot be pre-tested, so SWUK protocol ensures a structured risk-assessment-led approach to replace the RPS 298 guidance that allowed unclassified utility waste to move for reactive works.

Correlation is the issue that matters most – correlation accuracy must be as high as possible between the desktop and site-based risk assessments, as well as the lab data from the tested excavations. 1%, 2% or 3% of excavations must be tested and reviewed annually (percentage dependent on accuracy), with suspensions from the protocol in place for falling below 70% accuracy across two consecutive combined quarters. For example, maintaining accuracy above 93% means a 1% sampling threshold, but if it drops to between 85 and 93% then the number of excavations required to be tested doubles to 2% (also doubling the time and cost). There is a significant time and cost impact associated with a drop in the correlation between what is assessed on site and what is found in lab testing.

The correlation can be negatively impacted by avoidable process failures such as non-representative sampling, pH from cementitious material, blacktop within soil samples, and incorrect interpretation of lab data – accurate sampling is incredibly important to avoid these issues and maintain a high correlation.

Since the implementation of the Street Works UK Protocol, SOCOTEC has analysed thousands of blacktop, ground and soil samples from roadwork excavations. The testing carried out by SOCOTEC has revealed that from the samples classified as hazardous, TPH (hydrocarbons) is the most common reason for the hazard classification.

The prominence of TPH could be due to incomplete segregation of blacktop from the soil samples, significantly worsening classification outcomes for otherwise non-hazardous material through blacktop contamination of soils, causing correlation issues between the site assessment and laboratory interpretation. This elevated TPH levels can also be due to creosote coated telegraph poles, as creosote can leach into the area surrounding the pole.

Aside from TPH contamination, a high soil pH accounts for 32% of the hazardous classifications found in our data so far. A common cause for this is concrete content in made ground – particularly where recycled aggregates have been used.

Data from SOCOTEC’s testing and analysis demonstrates that the protocol is working as expected regarding the percentage of excavations found to be hazardous. SOCOTEC’s results show that 8.4% of our samples are hazardous compared the EA’s expectation of 15% hazardous samples – slightly better than predictions but still closely aligned with expectations. This is further shown through only 5.3% of blacktop/tarmac samples found to be hazardous and 10.7% of soils/sub-base samples as hazardous.

SOCOTEC’s testing indicates the Street Works UK protocol is working as intended, allowing street works operators to verify their site-based classification at an expected frequency. For more information regarding SOCOTEC’s waste excavation works and analysis, and support for SWUK protocol compliance, please contact us.