Stormwater Feasibiltiy: What you need to know

Ever wondered what factors determine stormwater-related tasks on engineering design contracts?  

stormwater engineering basin hydromod  BMP  SWPP SWQMP Drainage Study

A subset of the engineering services which SDE offers is in the field of stormwater including hydrology & hydraulics and treatment of development runoff.  Nowadays, a comprehensive work experience in this field is vital for almost all projects.  SDE has sustained this working knowledge through the years.  One way it can be reflected is in the engineering contracts themselves.  Having the knowledge and experience of being able to identify project issues before any work has even been done goes a long way to minimizing risks to both the client and engineer.  This article provides a glimpse into the thought process when developing a stormwater-related scope of work.

Stormwater Resource Engineers are constantly asked to provide input for cost proposals for prospective projects relative to the drainage and runoff treatment tasks of a particular project.  For example, SDE has recently provided proposals for project types ranging between small ADUs up to hundred-acre master planned developments as well as multi-family and commercial sites.  Each project is unique and presents different challenges and constraints. At the same time, they also present their own opportunities.  Knowing these factors and potential opportunities is vital to creating a profitable project. 

The stormwater task, when preparing cost proposals, has evolved from simply being a hydrology/hydraulic item with its ultimate deliverable being a single drainage/hydrology report. Now, the scope of work for hydrology/hydraulics for a site typically includes the treatment of runoff generated at a site. Over the last 15 years or so, it has been necessary to subdivide the stormwater task on proposals as a result of State and local regulations continuously increasing their stringent compliance requirements for treatment.  In fact, whereas the local hydrologic requirements have remained essentially constant over the last 17 years, treatment requirements have seen two major permit updates during that same span.  The following is a quick discussion on items for thought when preparing stormwater-related cost proposals during these times.

Prior to developing a scope of work, it is crucial to be efficient and to become acquainted with the site immediately and as thoroughly as possible.  Performing as much due diligence now, in respect to stormwater resource engineering, will pay for itself in the long run. 

In general, the hydrology task item encompasses essentially the same work that it would have needed 17 years ago.  However, as mentioned above, the work tied to stormwater treatment has seen changes and will continue to be updated with forthcoming permit revisions.  It is essential to keep abreast of regulation changes not just at the County level but within each local jurisdictional agency.  With respect to stormwater (hydrology/drainage/treatment), the following list is a sampling of brainstorm questions which would be most beneficial to know the answers to before completing a project cost proposal:

-Where is the site located and who is the governing agency?  Is the cost proposal reasonable given prior     working experience with the agency and their respective approval process? 

-What are the proposed improvements? Based on estimated site imperviousness, will the project be designated as a “Priority Development Project” or possibly a lower tier “Standard Project”?  

-What are the project constraints? Constraints could range from existing grading or utilities to client driven requirements.

-What is the soil condition at the site?  Has a soils report been completed or expected?

-What is the topography of the site and its watershed location?  Does it discharge into an exempt river?

-Is the site located within an area which has been preliminarily determined to contain Critical Coarse Sediment?

-What is the potential for non-typical treatment Best Management Practices such as pervious pavement, tree wells, dry wells, and can Green Street measures be applied to the project?  

-Is a construction phase BMP plan necessary as an added task? 

Let us know if we can help on your next stormwater project! We can be easily reached on our contact page or send any inquires to