Bank Stabilization and Bioengineering

Chicago Botanic Garden Great Basin Project

Confluence is delivering consulting and design services to help the Chicago Botanic Garden to meet its goal of creating one of the world's preeminent aquatic gardens. Confluence's role in this project is to provide specialty expertise in bioengineered shoreline stabilization and design to a multidisciplinary project team consisting of Oehme van Sweden, Conservation Design Forum, Brown and Associates, and JJR-Smith Group. Key to the success of this project is the creation of stable shorelines and submerged planting beds for collections of water lilies, lotus, and emergent aquatic plants. Through innovative design and unique applications of geotextiles, the team has successfully developed designs that will help the plant collections to flourish while facilitating regular maintenance and controlling the growth of undesirable plant species. The team was able to take the $3 million dollar project from the conceptual design stage to a final bid package in just two months time.

River Road Landfill Remedy Monitoring and Repair

Confluence was retained by Union Carbide to provide ongoing project monitoring and assessment of an award-winning bank bioengineering project that Confluence founder Jim Lovell co-managed while with a former employer. As part of 1998 monitoring activities, several reaches of bank were identified as needing repair and maintenance. Confluence prepared designs and specifications and provided construction quality assurance for the maintenance repairs. Confluence continues to provide annual inspection services for the project. The bioengineered bank was designed and constructed to protect a hazardous waste landfill adjacent to the Raritan River in New Jersey. Since construction was completed, the bank has experienced a 100-year and a 500-year flood with no signs of erosion or failure.

Geomorphic Investigation of Bank Failure on the Salamonie River

The services of Confluence Consulting, Inc. were retained to investigate bank failure on the Salmonie River in Huntington County, Indiana. The property is located about a mile upstream of the Salamonie Flood Control Reservoir atop a steep bluff, which is approximately 40 feet above the river bed. On August 30, 1998, high flows caused the flood control reservoir to back up and saturate the river banks. As a result of saturation, a large section of the bank next to the property manager's home failed. The bank failure destroyed part of the property manager's driveway and threatened his family's home, less than 70 feet away. After inspecting the site, bank failure was determined to be the result of a geotechnical condition called "rapid drawdown" in conjunction with erosion of the toe of the bank by the Salamonie River. Following the site investigation, Confluence submitted a technical report explaining the cause of the failure and assessing the risk of continued slope failures at the site. The report concluded by recommending various stabilization measures and estimating costs to remedy the problem. The report was used by park planning personnel to select appropriate and cost effective measures to address the bank failure.

Brush Creek Channel Stabilization and Greenway Development

To fulfill town master plan goals for an "aesthetic and functional gateway corridor" worthy of a world class resort, the community of Snowmass Village, Colorado obtained EPA 319 funds to restore several thousand feet of Brush Creek. This stream had become highly incised due to increased flood flows from urbanization (impervious surfaces) and the highly erodible soils found in the drainage. Prior to restoration, the stream flowed in an unstable gully up to 8 feet deep. Mr. John McCarty developed the conceptual designs and retained Confluence to oversee final design, channel reconstruction, landscaping and greenway development phases. To create a channel capable of withstanding mountain floods, the channel was constructed with thousands of large boulders to create a series of step pools. In addition, the channel bed was raised up to six feet in places, evenly distributing grade and hydraulic energy. The riparian area was re-contoured and planted with native vegetation. The project has become a showpiece for the town.

Stabilization of Deer Creek at the Michigan City Municipal Golf Course

Confluence designed a new channel for Deer Creek at the Michigan City Municipal Golf Course, Indiana. Prior to new construction, Deer Creek flowed approximately 500 feet in a culvert and an additional 500 feet in an undersized, channelized and eroding ditch. To gain support of the local golf community, an original watercolor was produced portraying the new plans. Designs called for removing the culvert sections and relocating the stream to a new, meandering channel. The new stream consists of a low-flow channel within a larger floodway, designed to accommodate the 100-year flood. Banks along the low flow channel were constructed using bioengineering techniques and stabilized with native sedges. Areas adjacent to the floodway were lined with drainage tiles to improve site drainage and re-seeded with fairway grasses.

Coffee Creek Channel and Floodplain Restoration

Confluence participated in a team effort with Lake Erie Land Company, J. F. New and Associates, and Conservation Design Forum to restore Coffee Creek and its floodplain in northwest Indiana. Designs include stabilizing over 3,000 feet of eroding stream banks using 5 different bioengineered bank treatments. Pools, spawning gravel and woody debris were incorporated into the stream channel to restore habitat for migratory salmon from Lake Michigan. Six floodplain areas totaling over 4 acres were excavated along the stream and will function to remove fine sediments during flood events, leaving clean gravel substrates in the channel. The new floodplains include oxbow wetlands and have been planted with native wet prairie vegetation to increase infiltration and groundwater recharge. These restoration efforts greatly improved habitat conditions for fish and wildlife at Coffee Creek.

Sand Creek Stream Stabilization

Confluence worked with J.F. New and Associates to complete the restoration of 3,400 feet of Sand Creek in Indiana for an exclusive golf course and development. The designs were developed to remedy severe bank erosion and channel incision problems caused by channelization and increased stormwater runoff. Wildlife habitat was integrated with golf course features to develop a unique design that utilized a combination of bioengineered stream banks and natural riffle grade controls. Planform and bedform diversity was incorporated into the design to provide habitat and improve aesthetics. HEC-2 analysis was used to meet Indiana Drainage Board water surface requirements and to guide the engineering of bank stabilization measures. The project is considered to be highly successful and received an environmental award from the National Association of Golf Course Superintendents. Moreover, steelhead from Lake Michigan are now known to spawn in the restored channel.