Environmental Projects Gwynns Falls Stormwater Pond Retrofits

As part of Baltimore County’s Gwynns Falls Stormwater Pond Retrofits, J.A. Rice, Inc. (JAR) performed topographic surveying services related to restoring Ponds 26, 27, 33, 47, and 110. Our scope of services included the following:

Survey Control

J.A. Rice, Inc. established Horizontal and Vertical control using GPS/VRS to the NAD 83/91 datum. The vertical control was referenced to benchmarks as shown on provided contract drawings (Baltimore County Control Monuments) using differential levels.

Survey Limits

Approximate survey limit areas for each pond was one ±1 acre, for a total of ±5 acres.

Topographic Surveys

The topographic survey included grade breaks, tops and toes of slope, spot grades, manholes, pipe inverts, and the surface features that would have impacted the design, including headwalls.

Existing elevation data was collected on a 25’ grid across the bottom of each pond from toe of slope to toe of slope. Additional elevation data points were taken at obvious high or low points on the project sites on an as-needed basis, including the emergency spillways. An electronic version of the survey data was provided to Baltimore County project engineer when collected.


Final deliverables included 1’ contours in an AutoCAD 2010 .dwg file.