Washington College GIS Program Maps Easton, Maryland, Stormwater System
The GIS program has undertaken a project to map the stormwater system of the town of Easton Maryland. Initially the focus will be on the portions of the system in the Tanyard Branch Watershed. The Easton storm water team consists of Sam Stanton, heading up the project, Joe Miloshevsky, the student leading the field team and Luis Machado. The goal of the project is to map surface features using GPS and inspect and document accessible subsurface features. Data collected in the field will then be used to “connect the dots” to develop a comprehensive digital representation of the stormwater network. Easton, being a large old town, possesses a stormwater system that is made up of a widely varying collection of structures, which presents a unique challenge. The field team has thus far encountered everything from small hand laid brick structures to modern day precast concrete structures large enough to house a compact car. The system is actually a combination of multiple types of stormwater features from several eras and is much more complex than it first appears.
The system contains more than 1,300 manholes and almost 1,200 Inlets which will be mapped and analyzed. A GPS point is being taken for each feature using a Topcon GR-3 receiver and Topcon FC-250 Field Controller. This equipment has the capability to collect points with accuracies greater than 1 cm horizontal and 2 cm vertical. The team also inspects and documents the surface inlets, the pit itself, and any pipes leading to and from the feature. Measurements are taken for inlets and outlets utilizing 17 and 25 foot Crain measuring rods outfitted with a Pipe Mic. These measurements are taken relative to the rim elevation, as determined by the GPS measurement, and will then be used to calculate the invert elevations.
With these instruments and the ArcGIS mapping program, the team expects to construct a map of the storm water system during the course of the summer. CAD files of the stormwater system were provided by the town of Easton, and while not entirely accurate it has thus far served as a valuable reference. With this as a reference, and the team’s combined brain power, the expectation is to map and document the town’s stormwater system and gain a better understanding of how water moves through that system especially in urban areas, which is essential to understanding the Tanyard Branch Watershed.
This project is an excellent example of how the GIS lab is providing our students experiential learning opportunities using real world projects. Training for the field team on the Topcon GR-3 was conducted by Lukas Duruttya from DiCarlo Precision Instrument and this training is being used by the project team to develop in-house training materials for all of our student apprentices. During the summer all twenty students working in the lab will get a chance to spend a day in the field learning how to use this equipment and therefore advance their understanding of precision GPS.