Recently, we received a call from a client asking if we do dam surveys. Our reply? Dam right we do!
The request was to stakeout a 75’ wide easement from the high-water mark of the Springton Reservoir located in Media, Delaware County. Our client was wondering if any property owners who backed up to the reservoir had built on or improved the land within these limits.
The first task was to identify where the high-water mark is. A high-water mark is defined as a point that represents the maximum rise of a body of water over land. Such a mark is often the result of a flood, but high water marks may reflect an all-time high or the annual high to which water levels will rise that year.
A plan provided to us indicated that the high-water mark was to be 1.5’ higher than the average ground elevation. The benchmark for this ground elevation was to be measured at the crest of the emergency spillway of the Springton Reservoir. Sounds simple enough. However, sending our field crew to walk across an active dam to get grade elevations would certainly get us a visit from an OSHA representative.
Thanks to our DJI Matrice 300 drone with a 3D lidar sensor, we can collect an enormous amount of data without risking injury to any of our employees.
We began by flying and scanning the dam face along with the embankment of the reservoir. This allowed us to precisely measure the crest of the spillway along with the current water surface elevation. Once the data was reviewed, a calculated spillway elevation was created and used for the benchmark of our project.
We added a 1.5’ user-defined contour to the lidar surface, which created our high-water surface line. Then, a 75’ wide offset was used to create the stakeout line for the field crew to ensure no structure or improvement encroached onto the existing easement.
Doing aerial data collection using LiDAR scanning is a common practice for us these days. Still, each job typically brings on new challenges and obstacles that excite and challenge our surveying team. Here at Howell, we love that our company keeps expanding in the world of land surveying while also prioritizing the professional development of our employees. This is what makes us a unique company that stands out among the competition.