The mandate: Make a vastly more detailed map of where and how stormwater flows off a big, flat industrial area in order to achieve and document compliance with new, stricter water-pollution regulations.
The challenge: The areas are so big—up to hundreds of acres—and filled with so many structures, features, and varied vegetation that water flows won’t be readily apparent to even the most experienced field inspector working at ground level, even with today’s best terrestrial surveying equipment.
TRC’s solution: Bring in drones to fly over each facility to generate a three-dimensional map with tens of millions of data points, called a “point cloud.” Then we followed up with our team’s deep experience in Geographic Information Systems (GIS) to refine those maps into super-precise site plans that identified the key drainage areas and surface-water flows and pathways. That, in turn, enabled TRC professionals to show our client where they’d need to lay new berms and install drainage to control stormwater, and what volume of water they’d need to deploy equipment to treat and where.
That’s the short version of an exciting, innovative project we recently worked on for a U.S. client with large industrial parcels at 14 locations. Many of these sites were graded and constructed back in a much different era of environmental awareness and enforcement, when the sole priority was to move stormwater away as fast possible. No one’s priority then was to track and control how chemicals, petroleum products, metals, and other contaminants might wash away with the rain.
Making it all the more complex: These are locations full of existing drains and culverts, but also buildings, sheds, storage containers, paved surfaces, unpaved tracks, piles of various materials, and other physical features that all affect which way stormwater flows. Ultimately, our task was to identify where on the properties rain and melting snow might collect what’s called “discharge of constituents of concern” and where that impacted stormwater would then flow—and have to be collected and treated to comply with pollution regulations. Of as much interest to our client was also document which stormwater flows clearly would not collect constituents of concern and could be discharged from the site without needing treatment.
It’s nearly impossible to imagine how we would have done this work without the drones, and definitely impossible to imagine us doing it (as we did) in months rather than years without them. To have engineers and surveyors walking around on the ground develop the level of accurate, detailed plans we needed would have been challenging, painstaking work, to say the least. In just 60 minutes or less of flight time, operating about 400 feet above ground, the fixed-wing drones quickly and accurately created the vast majority of the mapping information we needed, including elevation points about every 4 inches.
Our job at TRC became to shape and refine this giant dataset into an informative map. Less glamorous than the drones but just as important were software packages we configured to automate managing the millions of pieces of data collected by the drones and honed by our people to create the basis for our stormwater management plans at each site.
If you’ve ever faced the challenge of draining a badly-graded basement or garage, you know how maddening it can be to figure out where water wants to go. Imagine doing that at, say, a 100-acre industrial site. It’s also worth noting that this GIS approach can work for modeling any type of surface flow, including petroleum or chemical spills, and on any kind of terrain.
What TRC learned from this deployment of UAVs as part of an overall GIS strategy: If you’re managing an industrial park, airport, railyard, trucking terminal, or any facility that needs to stay on the right side of stormwater-discharge regulations or spill or leak regulations, drones can drastically drop the time and cost of drafting up the drainage you’ll need.