In 2007, the Hamilton County Parks Department had a serious erosion problem on the west bank of the White River Camp Ground located in Strawtown, Indiana. If the erosion continued, not only would an electrical and sanitary line be exposed, but the 10’ drop from the RV camp sites would continue to erode raising even further safety concerns. The Parks Department decided to locally fund the project and selected Indianapolis-based USI Consultants to perform the design. Due to their previous successes with vegetative systems, USI Consultants engaged D2 Land & Water Resource early in the design process.
Two designs were proposed along the White River depending on the location of bank in reference to the utilities. The first design was at the lower bank or where the steepest slopes with erosion closest to the utilities were located. At the base of the slope extending to the Ordinary High Water Mark (OHWM), an aggregate raft was built utilizing Mirafi 180N geotextile, Miragrid 5T geogrid, and Class 1 riprap. A 20” gabion sack was placed at the OHWM, where a 9 lb/ft3 density vegetated coir log transitioned to the soft armor system of permanent turf reinforcement mat. It should be noted that the coir log was secured (laced) to the gabion sack for stability.
The second cross section was designed for the area where only high bank restoration was required. In these areas, there was enough horizontal space in relationship with the utilities to properly slope the bank. Similar to the first cross section, another aggregate raft was built, but at the OHWM no gabion sack was used to transition to the coir log design due to the more gentle slope. The same 9 lb/ft3 density vegetated coir log was used to transition to the soft armor system. In the soft armor system of this section, Tensar BX100 geogrid was used to strengthen the newly backfilled surface slope as well as to secure the lower coir log to the bank. The sub sequential vegetated coir logs were stacked and laced at the TRM overlap locations.
The construction of this site occurred from Nov. 1, 2007 to March 15, 2008. During this time, there was 67 flood days, all overtopping some part of the vegetative system. From July 2009 photo, it can be seen that the flooding did not affect the stability of the vegetative system.
