Project Owner’s Name/Address:
Frederick County Division of Public Works
118 North Market St
Frederick, MD 21701-5422
David Ennis, PE
301-694-1557 Completion Date: August 2007
Project Features: - Brightwater, CCJM, M. Clar Colaboration
Performed a Rosgen assessment
Performed a complete survey including geomorphic features
Designed an E4 channel with innovative bioengineering and rock stabilization structures.
Performed H&H analysis
Calibrated the TR-20 model with the field determined discharges
Prepared and secured all permits
Prepared all construction plans and documents
The joint venture team comprised of Brightwater, Inc, Ecosite, and CCJM designed a stream restoration along approximately 450 linear feet of Ballenger Creek. The creek, a tributary to the Monocacy River, has a long history of agricultural and urban impacts. A County owned site on the creek was selected for stream restoration to provide improvements to water quality, in-stream and riparian habitat, and aesthetic conditions.
Project Objectives: - Restore the stream channel and riparian area utilizing natural stream channel design principles and bioengineering approaches to improve bank and channel stability and to reduce erosion.
Create a stream channel and floodplain that is dynamically stable, provides hydrologic and sediment transport continuity and re-establishes floodplain connectivity.
Create a range of aquatic habitats and associated riparian areas to enhance and support the existing ecological community.
Work within site constraints and other considerations, including ocal geology (e.g., possible karst), and existing trees, footbridge, sewer line and other structures and proposed walking trail.
Improve the aesthetic value of the reach.
Identify and incorporate educational needs into the project to facilitate future learning opportunities associated with the stream.
| Jim Gracie acted as Project Manager overseeing the coordination, QA/QC, and cost control.
Brightwater performed the assessment and design for Ballenger Creek. The assessment began in the office where historic and current aerial photos were used to help determine the cause and state of the instability. Gage analysis and regional relationships were used to calibrate the bankfull discharge determination. The field work included Wolman pebble counts, wetland delineation, assessment of riparian health, BEHI/NBSS analysis to assess bank erosion, and identification and flagging of probable bankfull indicators to be surveyed.
CCJM surveying services led by Thom Holbrook included developing a topographic map, a thalweg survey, detailed cross sections for the stream restoration design, and flood plain sections. CCJM also calculated flood flows for the design reach using TR-20. TR-20 data were prepared using the watershed modeling software.
Mike Clar of Ecosite completed the hydrologic and hydraulic analysis of the 450’ section involved in the stream restoration using HEC-RAS. Two geometric models were developed: one model of the existing conditions, and a second model of the proposed restorations. Mr. Clar calibrated the TR-20 model with the bankfull and 10 year flows.
Figure 1. Condition of stream banks before restoration Brightwater secured all permits, prepared cost estimates, construction documents, a sediment erosion control plan, and a performance monitoring plan.
The design implements an innovative technique to stabilize eroding banks using a combination of soil fabric lifts and imbricated rip rap with live fascines inserted. This technique creates the high vertical banks characteristic of the Ballenger E4 channel. The design also moved the meander bend of the channel away from a property line and sewer line by increasing the radius of curvature.
All project objectives were realized resulting in 450 LF of Restored Channel as photographed below. 
|
