Continental Mapping performed planimetric mapping via aerial imagery and bathymetric survey using a semi-autonomous hydrographic survey system within the Chatfield Reservoir in the eponymous Colorado state park to support additional water storage and conservation in the reservoir.

For over forty years, the Chatfield Reservoir, located in Chatfield State Park in the southwest suburbs of Denver, Colorado, has provided Coloradans with a water resource essential to agriculture, recreation, and the state’s livelihood. However, a growing water demand from agriculture and municipalities in Colorado’s northeast region forced conservationists to assess their resources and plan for the future. This sparked the Chatfield Water Reallocation Project, a coalescence of multiple government agencies and engineering partners to provide a solution. The U.S. Army Corps of Engineers (USACE) concluded that 20,600 acre feet of water storage (or an additional 12 feet of surface water level) could be added to the reservoir’s water storage while maintaining its flood control capabilities. USACE, in coordination with The Chatfield Reservoir Mitigation Company (CRMC) and SmithGroupJJR, Continental Mapping worked to turn this project into a reality.

Continental Mapping supported design efforts by collecting, producing, and delivering bathymetric and planimetric mapping data in the Chatfield Reservoir. Continental Mapping was chosen because of the company’s past performance in littoral environments, experience with conservation efforts, speed of deployment, and end to end support. The data Continental Mapping delivered supported the project team’s planning, engineering, and consensus building efforts.

The proposed increase in water level required detailed mapping of existing conditions to support engineering, particularly near public recreational areas. Continental Mapping performed aerial photogrammetric mapping of the reservoir’s marina, facilities, and utilities in an initial phase of the project. The detailed mapping of all facilities and utilities assisted designers in assessing design alternatives for the public facilities.

CMC Chatfield PlanimetricsFigure 1 Phase one of the project required planimetric mapping of the Chatfield Marina.

 

CMC Chatfield Surveyor with Hydrone
Figure 2 Surveyor operating semi-autonomous hydrographic survey system, Hydrone
The second phase consisted of bathymetric survey at two targeted locations: the boat launch and the public beach. Characterizing the bottom of the reservoir at these locations was important because these were points where the public would launch boats and swim, affecting safety and recreation. Using a semi-autonomous hydrographic survey system, the Hydrone, Continental Mapping’s survey crews completed the bathymetric survey in just four days. The Hydrone, a single-beam echosounder with GPS positioning, collected data at 100-foot intervals parallel with the shoreline every 50 feet. Thorough quality control ensured accurate depth readings and positional results. Deliverables included bathymetric, topographic, planimetric, and utility survey results in AutoCAD (.dwg) and ArcGIS (.gdb and. shp) file formats.

 

  

CMC BathymetryFigure 3: Bathymetric data shown where the South Platte River feeds into the reservoir, as well as the public boat launch.

Continental Mapping’s planimetric and bathymetric data supported the many teams involved with the Chatfield Reservoir Reallocation Project, from planning, to engineering, to construction. The additional water storage project was successfully executed after over three years. The project received final USACE approval on May 18, 2020, allowing the reservoir to store the additional 20,600 acre feet of water. The project team’s efforts ensure the region’s water security, giving farmers, cities, and civilians a sound and fertile future.

For an overview of the design process and results see SmithGroupJJR’s project summary here.