Low Impact Development Life Cycle Costing Tool



Accurately estimating the life cycle costs for low impact development (LID) practices can in itself be a costly and time-consuming process. The STEP life cycle costing tool (LCCT) facilitates this process and allows users to generate realistic, reasonably accurate costs estimates for LID stormwater practices.  The tool, which was first released in 2013, has recently been updated to Version 2.0 which includes the following updates and new features:

  • Increased transparency and usability. Users can now access the tool’s back-end to modify assumptions, unit costs, design defaults, etc. 
  • Added cost estimation for wet ponds in order to facilitate direct comparison to LID options  
  • Added dry ponds as an LID practice 
  • Updated line costs to 2018 based on RS Means data and information obtained through consultation with suppliers and project managers 
  • Refined algorithms to reflect line cost updates and construction practices 
  • Added a land value option to all BMPs. This allows users to account for land acquisition when required and for opportunity costs when otherwise developable land is used for stormwater management 
  • A sensitivity analysis that uses constructed projects to test the tool’s accuracy 
  • An LCCT user guide which provides a brief introduction to the tool and demonstration of how it can be used to suit their purposes   

The LID practices evaluated in the report include bioretention cells, permeable pavement, infiltration trenches and chambers, enhanced swales, rainwater harvesting and green roofs.  Dry swales and perforated pipe systems were considered to be similar to bioretention and infiltration trenches, respectively, and therefore were not evaluated as separate practices.  The tool does not assess LID-related cost savings related to improved aesthetics, air quality, community livability and other public benefits, as these savings are best evaluated in relation to specific case study examples. 

STEP encourages feedback on the LCCT from users. Your comments can help us to improve the tool for future updates. Users will be notified of future updates to the tool through the STEP Water newsletter, the Water Sampler. You can sign up for the newsletter here.