How much will your remediation project really cost?

Full text: Introduction - Predicting the cost of remediation projects has been a major issue for the industry since the remediation industry emerged as a separate field of engineering in the 1990s and today many projects still end up in disputes over cost overruns. The reasons are manyfold but the crux of the problem is that cost estimates are based on quantity estimates, and quantity estimates are notoriously uncertain. This is because they are based on subsurface data which may not be representative, coupled with many assumptions, extrapolations, interpolations and guesstimates. A second but lesser source of uncertainty is the monetary rates assumed for various remediation activities. The third source of uncertainty is the many ancillary engineering related costs that may be forgotten in the process of focussing on the remediation part of a project. The presentation will analyse Ventia's historical data base of remediation project scopes and costs to identify the ancillary project activities that can significantly increase the overall cost of remediation for what appears to be an otherwise straightforward remediation project. Methods - Ventia's project data base of mainly ex-situ remediation projects has been dissected according to the main types of remediation sites including gasworks sites, chlorinated chemical sites, hydrocarbon sites, landfill sites, defence sites and sediment projects. These have been augmented by published remediation case studies. The costs of remediation have been converted to 2018 dollars, and the adjusted costs crossplotted against remediation volume to identify outliers in the overall remediation rate for the various types of sites. The scopes and costs of the outliers have then been dissected to identify the reasons for the higher remediation rates. Results and discussion - The reasons that remediation rates (and costs) within the various types of remediation projects may vary widely are multiple and may include among other things: Geotechnical considerations particularly where retaining walls or difficult foundation conditions exist; Incorrect predictions of waste classification, where the classification of the waste is underestimated; The different types of remediation methods that may be used to remediate a particular type of contaminant; Unforeseen (and foreseen) technical issues; Time and space considerations (often driven by development requirements); and The application of landfill levies. Conclusions - Remediation rates and costs can vary significantly for types of contaminants and contaminated sites. The reasons are manyfold, but if any are overlooked in project planning significant project cost overruns may eventuate. (author)