Home > UAV Aerial Services Blog > Canadian UAV Solutions provides Hybrid Municipal Drain Survey

Client:

R.J. Burnside & Associates Limited

Jeff Dickson, P.Eng. (Project Engineer)

Natalie Connell, P.Eng. (Engineering Assistant)

 

Purpose:

Town of Innisfil – Carson Creek Drain Survey

Approx. 6 km hybrid UAV & Ground topographic survey of the Carson Creek municipal drain. The survey area included water bodies, shoreline, heavily wooded areas, bridges & culverts, roadways and/or streets, fences, property boundaries, and other obstacles which would hinder and slow traditional survey methods. The UAV data would be used to alleviate ground survey time, as these obstacles would be located through the planimetric imagery, while the topographic data from the UAV scan would fill in the blanks between survey profile and cross section shots.

 

Scope of work:

UAV Data Collection

  1. Topographic scan of drain and 60m past top of bank providing a classified DEM point grid at 1m interval.
  2. Contours at .3m interval.
  3. Orthographic Image at various resolutions (3cm, 5cm, 10cm, and 30cm).
  4. Planimetric Image Identification of:
    • Private and public building footprints, driveways and material, roadways and/or streets, a Metrolinx crossing, firepits, landscaped areas, fences lines and materials, other private features such as playground equipment, ancillary buildings, foot bridges, ;
    • Utilities: markers, poles, guys, pedestals, overhead lines, etc.;
    • Other features such as Trees and their chainages, retaining walls, guide/guard rails, storm pipes or drain outlets, storm structure out letting into the drain (catch basins/manholes), spoil piles, etc.; and
    • Location of bends and meanders to determine the true length of the drain.

 

Ground Survey

  1. Survey of drain bottom and top of bank elevations to incorporate into a Profile at an interval of ~ 25m.
  2. Sediment depth to determine excavation requirements at each drain bottom ground shot location and capture any low-flow channel shapes that might exist.
  3. 100m Cross Section intervals – bottom width of drain, width of waterflow (if much different), top of bank, an offset shot from each top of bank.
  4. Geo tagged photos of material in the drain bottom – firm, stony, cobbles, gravelly, sediment deposits; etc. along with Geo tagged photo evidence of notable erosion sites and obstructions.
  5. Length of culverts/pipes, diameter or dimensions, material, u/s & d/s inverts & obverts, skew angle, and longitudinal cross section at each drain crossing (edges, centerline, etc.).

 

Conditions and Requirements:

  1. Topographic Accuracy and Orthographic mosaic ground sample distance (GSD) requirements for the UAV data was >3cm GSD, Open areas were subject to 5cm accuracy while vegetated areas were to be within 30cm.
  2. Top of bank, bottom of bank, edge of water, center of drain, and culvert invert and obvert shots were to be within 2cm accuracy.
  3. Feature location information was to be provided from the planimetric image provided through the orthographic mosaic data, and was to be accurate within 6cm.

 

Methodology and Timeline:

Canadian UAV Solutions, along with the Burnside Team, traversed the length of the drain, recording and photographing feature locations and descriptions, while distributing Ground Control Points (GCP’s) throughout the area. The UAV crew performed 2 flights using an eBee+ RTK with the visual observer placed at the ends of the drain during the western half and eastern half respectively. This portion took 2 days to complete, with the majority of the time attributed to walking and recording conditions along the drain length. The eBee+ RTK captured ~800 photographs. Correcting the RTK location data, processing the Planimetric Ortho Mosaic, marking the features within the Ortho, and embedding the ground photos into an ArcGIS database and map took an additional 3 days. While this was on-going, ground survey technicians were obtaining the drainage shots and other high accuracy requirement feature data. The 6.2km drainage profile shots took a 2-man crew 10 days in the field to complete. Once all the data was collected, Canadian UAV Solutions’ Photogrammetry Specialist generated a hybrid Topographic grid using the drone data embedded with the drainage shots provided by the survey technicians. By combining information from both sets of survey data, the end result was a unique and highly detailed topographic representation of the drain and surrounding 60m buffer, which was accompanied by aerial imagery and ground-based imagery.

Overall, the time it took to generate, combine, identify, and QA/QC the data took 15 business days.

 

Summary:

Canadian UAV Solutions was able to provide a unique data set in a fraction of the time compared to traditional aerial or ground based surveys when performed on their own. QA/QC reports a RMSE on check points found on bare earth were no greater than 5cm on the Z and 3cm on the XY, well within the accuracy requirements of this project. Should your Municipality or Engineering group be open to exploring a brand new, efficient data set for your engineers to utilize, contact Canadian UAV Solutions today, and we will be happy to answer your questions or provide quotations.

 

Testimonial:

CUAV staff (very conveniently) made “ALL” the necessary arrangements with respect to take-off/landing sites, flight paths; etcetera.  Further, and even though the Drainage Act provides power of entry on land, this methodology eliminated the need to request such access.  It also avoided climbing fences to collect data on the “other side” and avoided collecting horizontal & vertical data at the corners of the numerous building adjacent to the drain.  The topographic data provided the ability to determine the composition of most hard surfaces (gravel vs asphalt, etc.) as well as identifying other features on private property; etcetera without the need to inventory each one on the ground.

There were cost savings based on the estimated budget (both time required and value) prepared by Burnside and the quote provided by CUAV.  Also, and even though UAV technology had seldom been (to the present anyway) a used methodology for the survey of a municipal drain, it also provided 2020 topographic (aerial/planimetric) data.

There was an overall in-the-field time saving with an end result which provided more data than is normally required for a traditional drain survey. However, a significant portion of the length of the drain was through an urbanized and built-up area between the upstream agricultural lands and the outlet into Lake Simcoe and the additional data collected is and will be quite useful as we move through the public engagement process under the auspices of the Drainage Act.  The 2020 topographic (aerial/planimetric) data will also facilitate determining the most and least intrusive working space along the course of the drain, especially the portion in the urbanized and built-up area.

Jeff Dickson

P.Eng.