Task:     Hydrology and Hydraulic Analysis and Erosion and Sediment Control Design

Challenge:          The stream is located within the City of Laurel and is highly eroded and causing sediment deposits downstream. The community requested that restoration of the stream be initiated by the county department of environment to stabilize the reach and improve downstream water quality.

Results: A.D. Marble provided the hydrology and hydraulic (H&H) analysis and the erosion and sediment control design and obtained approvals through the Prince George’s County Soil District. The existing channel was highly eroded and therefore the restoration design involved regrading and stabilizing the bed and bank. Erosion control measures included pumping the existing stream around the work area, filter bags, stabilizing construction entrances, and a filter log.

A.D. Marble worked proactively with the prime client and Prince George’s County Department of the Environment to integrate relevant information from the H&H analysis into the design process, including:

• Analyzing the watershed for recent development and commercial construction to update the stream stats regression model.
• Analyze the water surface elevations of the 2-year through 100-year storms to ensure no additional flooding will result from the stream restoration.
• Identifying locations where high velocities and shear stresses could result in erosion. Suggested stabilized slopes and rock walls be incorporated into the design.
• We used our knowledge of LOMR regulations and on-staff Certified Floodplain Managers to ensure the project and H&H analysis is compliant with FEMA regulations, reducing effort and coordination during the LOMR process.