Excavations are a significant cost to contractors undertaking repairs to water pipes and sewers, but how do we ensure that reinstatement of these excavations will endure into the future?
There is a general desire to develop techniques that minimise the size of the excavation as these are typically cheaper and quicker, reduce the risk of interference from other utilities’ infrastructure, are less disruptive to the local community and businesses, use less material and have lower overall CO2 emissions. However small excavations have problems with compaction and this makes them vulnerable to failure because the air-void is outside the Specification for the Reinstatement of Openings in Highways (SROH) standard. Repairing failures increases the cost of an individual excavation many times.
The objective of this project is to reduce the overall costs of reinstatement by identifying options for improving and auditing compaction in small excavations such that they can achieve the SROH standard, or an acceptable alternative.
BUSINESS BENEFITS TO CLIENTS
- Contractors will eliminate the substantial costs associated with repairing failed reinstatements
- Reduced liability and robust defence against Highways Agencies notifying failures in the future by having improved records of the quality of the reinstatement.
The project will work with contractors to fully understand the current practices associated with small excavations and the limitations of existing compaction techniques. The nature of the failures associated with coring investigations will be given particular attention and the project will liaise with the work being undertaken by John Moore's University, Liverpool, on reviewing the relevance of the air-void element of the current SROH.
Specific tasks will include:
- Discussion and field visits with contractors to identify problems and common root causes that would lead to notified failures in small excavations.
- Agree the detailed scope of the experimental programme with project participants based on the results of the field visits.
- Investigation of compaction equipment in WRc's underground testing facility, testing the performance of available equipment. The work will include the development of compaction testing/auditing methods.
- Development and demonstration of new methodologies, including field testing.
PROJECT OUTPUT AND IMPLEMENTATION
- Simple, structured methodology and tools for effective reinstatement of small excavations, with case studies and supporting workshops.
- Recommendations, as appropriate, for any updates to the SROH.
RELATED WRc WORK
- Development and management of Civil Engineering Specifications for the Water Industry (7th Edition) 2011.
- CP373/373a Cost effective management of street ironworks (2009-11).