Case Study: Davis & Floyd, Inc.

Davis & Floyd Shaves Weeks off Floodplain Modeling Projects

Background Information

On the Atlantic Coast, South Carolina is subject to heavy rains and storm surges. As development has increased in flood prone areas, flood risks have increased for citizens and properties. In the past 12 years, the state has seen flood and hurricane damages totaling more than $7 billion.

With four offices in South Carolina, the engineering firm of Davis & Floyd faces these challenges head on. Davis & Floyd provides engineering, architectural, environmental, and laboratory services to industrial, commercial, municipal and governmental clients. For more than 30 years, Engineering News-Record has ranked the firm in the top ENR 500.

Over the years, the firm has used a variety of engineering tools for floodplain modeling, including HEC-RAS, HEC-2 and AutoCAD Civil 3D software. Used alone, HEC-RAS and HEC-2 require considerable manual labor from their engineers to complete a floodplain project. And, the built-in digital terrain capabilities in Civil 3D proved limited on certain projects.

“We tried to use the Civil 3D software to do something it wasn’t designed to do. When there were mounds or hills in the floodplain, the software would stop at the hill and didn’t handle curves in the channel well,” said Tom Baumburger, Engineering Technician. “We thought it would be good for 3-D capabilities, but found RiverNET is actually a better choice.”

Automating Modeling within AutoCAD

Davis & Floyd brought in RiverNET from BOSS International to speed up their floodplain modeling. The sophisticated river modeling software automates HEC-RAS and HEC-2 modeling within AutoCAD.

With RiverNET, engineers can model features directly within AutoCAD, including bridges, culverts, spillways, levees, bridge scour, floodway delineations, floodplain reclamations, and stream diversions and realignments.

For two engineers new to RiverNET, their first project involved the Sawmill Branch of the Ashley River in Summerville, South Carolina. The firm needed to generate floodplain maps for two roadways that paralleled and crossed the branch.

They initially used just HEC-RAS and AutoCAD Civil 3D, but found the approach too cumbersome. “We would have had to do the work by hand because the Civil 3D software was incapable of running floodplains along mounds in the channel bank,” Baumburger said.

After that experience, they turned to RiverNET. Engineers quickly began using the software without any official training, using the provided online training videos and other resources available from BOSS International ’s website.

They took their previously created HEC-RAS model that was based on schematic coordinates, and imported it into RiverNET. From there, the software automatically converted the schematic coordinates to real-world coordinates.

“RiverNET has nice routines for converting HEC-RAS models to actual coordinates and placing it geospatially,” said Jennifer Skinner, Staff Civil Engineer. “It’s just a couple of clicks and you have it generating the floodplain map.”

Ready for Clients, FEMA

On the Sawmill Branch CLOMR project, engineers extended culverts at a crossing in the branch with base elevation increases of less than a tenth of a foot. Unlike the native Civil 3D application, RiverNET allowed them to accommodate anomalies like hills in the floodplain and base elevation changes as needed.

That gave the team documentation to show FEMA that projected changes to the floodplain would not impact any structures beyond what was currently affected.

On a recent LOMR project, Davis & Floyd updated maps to send to FEMA showing that an approved roadway does not fall within floodway limits.

RiverNET generates results that the firm can give directly to clients. With the ability to create an AutoCAD file that delineates the floodplain and its ability to generate ArcGIS floodplain maps, the firm can provide results to clients that require either or both.

Additionally, they produced the floodplain map for the exhibit material, plus had an aerial background displayed on one of the exhibits for the client to see exactly what areas were in the floodplain. They also showed parcel limits and county boundaries.

“The client definitely accepted and endorsed our project and was happy with the finished product,” Skinner said.

HEC-RAS Models in One-Tenth the Time

As the two engineers used RiverNET for the first time on live projects, they occasionally turned to BOSS’ technical support for assistance – and found support personnel exceptionally knowledgeable and responsive.

“They went out of their way to help out. They’re top-notch,” Baumburger said.

Solid support is simply icing on the firm’s RiverNET experience. Compared to other methods, the engineers estimate that RiverNET allows them to generate HEC-RAS models in about one-tenth the time. Over the course of a project, that level of efficiency saves weeks over modeling with just HEC-RAS and AutoCAD, which was effectively a manual process.

“Davis & Floyd works on a lot of big floodplain projects,” Skinner said. “RiverNET is a big time-saver for us and very accurate software. I trust the software more than I trust humans. It produces the best results possible.”