How Drones Can Benefit Stormwater Retention Basins

Can drones for stormwater retention basins save a crew real time?

Yes, for the parts of the job that mean walking long embankments and reading the water line. A drone can fly the crest, the side slopes, the outlet and the approach channel in one session, then return imagery that a crew can review at a desk. Drones for stormwater retention basins are best at finding erosion, debris and sediment buildup, the conditions that change slowly and are easy to miss from the ground.

They do not replace a full engineering survey, and they do not see underwater. What they do well is give a facility manager a repeatable picture of the basin after every storm or season, so field crews go to the right spots first. The gain is mostly in hours and coverage, not in a new kind of answer.

Service Robot Co. is a US commercial robot integrator. We help operators pick the right aerial setup for their site, arrange it through financing, and set up the flight and data workflow with their own staff. The sections below cover what the work looks like today, what changes, and what to expect.

What does checking a basin involve today?

A retention basin is a large, mostly open site with steep embankments, a forebay where sediment settles, an outlet structure and a spillway. Inspection usually means a crew walks the crest and side slopes, looks for rills, slumps and debris at the outlet, and notes sediment at the inlets. On a big basin that walk can take most of a shift, and the crew can still miss the far side of the pond.

Measuring sediment is harder. According to Stormwater.com, reporting on the City of Hamilton, Ontario, the city's earlier method placed a surveyor's GPS receiver on an extended range pole to measure sediment elevation at 10 locations across each facility. Under that method, the city's crew measured 2 to 3 facilities per day. Every point is a stop, and every stop is labor.

The walk also has a timing problem. Checks tend to happen on a calendar or after a complaint, so a washout that starts after a heavy storm may not be seen until the next scheduled walk. A drone flight can be scheduled the day after a storm, which gives the maintenance lead a clearer picture while the evidence is still fresh.

What are the main benefits?

The first benefit is time. According to an engineering firm's project write-up, work that once took multiple surveyors a full day can now be completed by a single operator in under an hour. A drone echo sounder vendor reports that one consulting team completed a retention pond survey 75 percent faster than its previous boat-based method. That is a vendor-reported figure, so treat it as a planning number and check it on your own site.

The second benefit is repeat coverage. Because a flight is quick to repeat, you can compare this spring's imagery with last fall's. A drone association's flood damage guide says LiDAR and photogrammetry are particularly useful for measuring embankment change, and that repeat surveys show where material has been lost. That turns a judgment call about erosion into a record you can date.

The third benefit is a better basis for decisions. Vendor material on post-storm inspections describes documenting sediment distribution and conspicuous areas to support decisions on cleaning or maintenance. A dated image set also answers the question a board or city office will ask, which is why a crew went to one embankment and not another.

How does a drone work a basin day to day?

Day to day, the work is planned as a route rather than a walk. An operator flies the crest and embankments with a set overlap so the images stitch into one map. A drone echo sounder vendor reports that a 5 to 10 acre pond at 10 meter line spacing typically takes 40 to 60 minutes of flight time, plus setup and data download. The flight is a part of the shift, not the whole shift.

Imagery goes to the people who maintain the basin. The useful outputs are a map for locating erosion, a dated image set for comparing change, and, where terrain change matters, a surface model that shows how much material has moved. A crew lead can then sort findings into clean now, watch, and call the engineer.

Timing matters. Fly when the water is low and the slopes are dry, and avoid wind or rain that would blur the images. Keep the same route and altitude each time, so the comparisons hold.

Which parts of the basin does a drone cover?

A retention basin is several work areas, and a drone reaches most of them from above. The areas below are where the flight is most useful, and where a crew still needs to go in person.

The outlet side deserves a close look. A drone association's dam guide says drones can inspect visible surfaces for cracking, erosion, debris accumulation and general condition, but that close inspection may still be needed where water flow prevents adequate visual assessment. Use the drone to find the problem, then send a person to confirm it.

How does a drone work alongside your existing staff?

A drone does not run the basin. It shortens the walk. Someone still has to plan the flight, review the images, decide what needs a crew, and clear debris, and that is usually a maintenance lead, a grounds crew or a contractor. The aim is a robot plus a smaller team that spends its time on the spots that need hands, not a setup with zero staff.

The Bureau of Labor Statistics reports that May 2024 employment was 943,430 for landscaping and groundskeeping workers, with 124,130 first-line supervisors of those workers. That is a large national workforce, and it means training the people who fly the drone and read the data is a normal part of the job. Stormwater.com, reporting on Hamilton's pilot, notes that constantly training student employees was part of the crew's work during the pilot.

What drives the savings?

Savings come from hours, not from a single headline number. The main drivers are the hours a crew spends walking and reading the basin, the number of basins one crew can cover in a week, and how often the survey is repeated. A flight of 40 to 60 minutes on a 5 to 10 acre pond, plus setup and download, set against a full day for multiple surveyors on the same job, is the kind of range to test on your own basins.

Hamilton's own projection gives a sense of throughput. According to the City of Hamilton, as reported by Stormwater.com, a trained crew doing this work would likely complete 3 to 4 stormwater management facilities a day depending on size. The city's earlier crew managed 2 to 3 per day. The difference between those two ranges is the planning question for your program, and it depends on how many facilities you have.

Start by timing one current inspection cycle, so you have your own baseline before you compare. Your result will depend on basin size, access, the terrain of the embankments, and whether the drone replaces a walk, a survey or both.

What can a drone not do?

A drone cannot see under water. Underwater scour is generally outside the capability of normal aerial imagery, and sediment depth on the pond floor needs a depth measurement, such as a drone-mounted echo sounder or a survey. Drone data also does not replace professional survey work when exact design facts are required.

Dense growth, wet ground and glare can hide erosion in images. Water flow can block a clear view of an outlet or a pipe, so a crew still needs to go in. Plan the drone as the first look, and keep hands on the checks that need certainty.

How do you get started?

Start with a free site assessment. Service Robot Co. is a US commercial robot integrator, so the first step is a look at your basins, access points, embankment heights and the inspection reports you already keep. From there we recommend the right aerial setup for your site, lease it through financing, and set up the flight route, the data workflow and staff training.

The payment comes in the quote that follows the assessment, so you see the full figure for your sites before you decide. After go-live, we service the equipment nationwide, so a problem on one basin does not stop the program. Many operators start with a pilot on one basin, compare a baseline cycle with the first drone cycle, and expand from there.