CHRISTOPHER B. BURKE ENGINEERING, LLC

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1 CHRISTOPHER B. BURKE ENGINEERING, LLC Yellow River Sediment Control Evaluation Preliminary Engineering Report Starke County, Indiana Prepared For: 3-County Drainage Board February 2012

2 DRAFT YELLOW RIVER SEDIMENT CONTROL EVALUATION STARKE COUNTY, INDIANA PRELIMINARY ENGINEERING REPORT Prepared for: 3-County Drainage Board 53 East Mound Street Knox, IN February 2012 Prepared by: Christopher B. Burke Engineering, LLC 115 West Washington Street, Suite 1368 South Indianapolis, Indiana CBBEL Project No. 19.R110416

3 Table of Contents Page Disclaimer... 3 Executive Summary Background Location History Previous Studies Objectives Remediation Project Development Road Map Consideration Existing Conditions Yellow River Description Schematic Design Project Site Identification Design Discharge Determination Specific Gage Analysis Grade Control Bank Stabilization Treatments Conceptual Opinions of Probable Cost Stream Stabilization Construction Costs Potential Cost Considerations Road Map Considerations Meander Belt Delineation Equilibrium Slope Assessment Stream Monitoring Program Additional Considerations Permitting Considerations Hyrdologic & Hydraulic Modeling Detailed Topographic Survey Project Adaptability Partnership Opportunities Potential Funding Sources Conclusions and Recommendations Conclusions Recommendations References Christopher B. Burke Engineering, LLC 1

4 List of Tables Table 1: Design Discharge Comparison Table 2: Maximum Velocity and Shear Stress Table 3: Project Site #1 Stabilization Treatments Table 4: Project Site #2 Stabilization Treatments Table 5: Project Site #3 Stabilization Treatments Table 6: Opinion of Probable Cost for Project Sites List of Exhibits Exhibit 1 Yellow River Watershed and Stream Network Exhibit 2 Project Site #1 Schematic Layout Exhibit 3 Project Site #2 Schematic Layout Exhibit 4 Project Site #3 Schematic Layout Exhibit 5 Yellow River Meander Belt Exhibit 6 Sediment Monitoring Locations List of Appendices Appendix 1 USACE Preliminary Reconnaissance Report Appendix 2 USACE SIAM Case Study Appendix 3 Site Photographs Appendix 4 Design Discharge Calculations Appendix 5 Grade Control Structures Appendix 6 Bank Stabilization Treatments Appendix 7 Conceptual Opinion of Probable Costs Appendix 8 Meander Belt Determination Appendix 9 Sediment Monitoring Information Christopher B. Burke Engineering, LLC 2

5 Disclaimer This report was prepared by Christopher B. Burke Engineering, LLC (CBBEL) for the 3-County Drainage Board, 53 East Mound Street, Knox, IN The report presents the results of CBBEL s preliminary evaluation of the repair of streambank erosion along three (3) reaches of the Yellow River in Starke County, Indiana. CBBEL used a digital elevation model with a cell size of five feet obtained from the IndianaMap website for the project area; the mapping does not match existing conditions in the vicinity of the project in all cases due to the vertical accuracy of the dataset. Channel flow velocity estimates are based on a HEC-RAS model downloaded from the Indiana Department of Natural Resources (IDNR). Material quantities used to estimate probable construction costs are based on visual observations, the IndianaMap DEM, photographs, limited field measurements, and detailed aerial photography, also downloaded from the IndianaMap website. A more detailed ground survey of the project area is required for more accurate analyses. The cost estimates should be used for budgeting and planning purposes only; a more accurate cost estimate should be prepared following the site survey and detailed design of the repairs. Information describing possible solutions to the apparent issues and associated repairs are intended for guidance only. Detailed design plans and specifications from a qualified professional engineer should be obtained before performing any repairs or modifications to the stream channel. Only qualified contractors should be employed to install the necessary measures. Permits from state or local agencies will be required to perform the channel repairs. The full extent of required permitting will depend on the magnitude of the selected repairs. Christopher B. Burke Engineering, LLC 3

6 Executive Summary This report contains the results of a preliminary engineering evaluation of streambank stability and erosion issues along three reaches of the Yellow River in Starke County: 1) along State Road 8 at CR 700 E; 2) near State Road 23 at CR 150 S; and 3) near County Line Road north of CR 250 S. Future considerations are also discussed, including conclusions and recommendations for analysis and rehabilitation projects. Existing Conditions The banks along the Yellow River are experiencing active erosion. Homes adjacent to the river are subject to varying degrees of risk due to the bank instabilities, and the continued migration of the alluvial channel. Bluffs exist in several areas with bank heights of up to 20+ feet. Other, and much more numerous, unstable areas have eroded bank heights of 3 to 5 feet. The erosion of the channel bed and banks is resulting in excessive sediment transport in the channel, leading to severe aggradation in downstream reaches. Engineering Evaluation of Project Sites CBBEL evaluated the condition of the main stem of the river to identify the potential project sites. Design discharges were approximated for bank stability mitigation strategies at each site. Results of a specific gage analysis are given, and key factors of grade control implementation are discussed. Finally, bank stability measures are discussed, and specific site rehabilitation measures to address the bank stability issues are described for each potential project site. Expected project costs ranging from $895,800 to $1.1 million were detailed. Road Map for Long-Term Mitigation The Road Map tasks include the estimation of the meander belt width through Starke County, suggestions for limiting the sediment transport capacity of the river, data requirements for design of sediment capacity-limiting infrastructure, and the proposal of a stream and tree monitoring programs. Development of larger data sets for future channel rehabilitation design was encouraged. Project permitting requirements are addressed, as well as future data needs for developing complete permit applications. Partnership opportunities are mentioned, including collaboration with government and higher education entities to help solve the unique issues found in the Yellow River basin. Potential funding sources were also described. Recommendations The following actions are recommended: 1. Implement a sediment monitoring program, as soon as feasible. 2. Select stream rehabilitation project for construction as a demonstration project. 3. Authorize CBBEL to proceed with design, permitting, and creation of construction documents. 4. Authorize CBBEL to assist in further developing the Road Map for long term control and stabilization of the Yellow River streambed and banks. Christopher B. Burke Engineering, LLC 4

7 1.0 Background 1.1 Location The Yellow River is located in northwestern Indiana. The headwaters of the river begin in St. Joseph, Elkhart, and Kosciusko counties, and flow generally south and west in direction. The main stem of the river passes through Marshall and Starke counties, receiving flow from 15 major tributaries along its entire length. The Yellow River watershed is approximately 538 square-miles and includes nearly 800 miles of channel. At nearly 60 miles in length, the main stem of the river is a small portion of the hydraulic system, with the majority of the stream network being composed of manmade ditches and canals. The mouth of The Yellow River is located near English Lake, at the confluence of the Yellow and Kankakee rivers. See Exhibit 1 for a map of the Yellow River watershed and stream network. 1.2 History The Yellow River watershed was once a part of the Grand Kankakee Marsh, which covered nearly 800 square-miles, spanning across eight counties. Beginning in the early 1800 s and continuing to the present day, the marsh has been extensively ditched for agricultural use. Changes in land use practices and hydrology appear to have caused severe instability in the Yellow River. Extreme amounts of erosion in the upstream reaches have caused aggradation in the lower reaches, where portions of the channel bottom are now above the adjacent land surface; side levees constrain the river to its current location. The Yellow River has been cited as a major contributor to the sediment load found in the Kankakee River, and subsequently to the Illinois River. 1.3 Previous Studies Many studies have been completed on the Yellow River and the greater Illinois River basin. The studies have focused on the sediment supply to the river systems, the deposition of sediment in the Illinois River, and the river segments contributing to the aggradation of the Kankakee and Illinois rivers. The following studies were selected based on their relevance to this preliminary engineering report. Christopher B. Burke Engineering, Ltd (now LLC), working with the IDNR, completed a sediment transport study on the Kankakee River and a supplemental sediment study on the Yellow River in The studies included the creation of HEC-6 sediment transport models to develop a baseline condition that would be used to assess the impact of the wide levee alignment presented in the February 1989 Kankakee River Basin Master Plan Report. The models were also used to compare the impact of several sediment loading mitigation alternatives. The report concluded that the wide levee alignment increased the local scour experienced at several bridges along the Kankakee River, with negligible impact to sediment transport characteristics of the remaining portions of the river. Four sediment mitigation treatments were examined, including watershed best management practices (BMPs), overbank sediment basins, tributary sediment traps, and in-channel sediment traps. Six sites along the Kankakee were identified for implementation of one or more of the treatments listed. Conclusions from the supplemental report Christopher B. Burke Engineering, LLC 5

8 suggest that the Yellow River does indeed supply a significant portion of the sediment inflow to the Kankakee River, with the Kankakee providing the largest sediment load to the Illinois River. The total annual sediment load estimated for the mouth of the Yellow River was 28.9 acre-feet. No analysis was performed to determine the impact of potential mitigation projects along the Yellow River. In 2006, the U.S. Army Corps of Engineers (USACE) published a preliminary reconnaissance report for the Yellow River watershed. The purpose of the study was to understand the impact of the Yellow River on the Illinois River basin. Holistic problem definition was cited as the purpose for the project to facilitate future projects aimed at restoring aquatic habitat through naturalization of hydrologic, hydraulic, and sediment transport processes. The report provided the following list of the major problems observed the in the Yellow River watershed: 1. Altered hydrology and hydraulics 2. Loss of floodplain connectivity and function 3. Unnatural, excessive sediment / sand loading and transport 4. Altered physical processes (e.g. cut and fill alleviation) 5. Loss of channel morphology and in-stream complexity 6. Habitat fragmentation 7. Loss of aquatic connectivity (barriers to fish and mussel passage) 8. Extreme loss in diverse riparian plant communities Five alternatives were provided which could be expected to improve the condition of the watershed. The alternative summary, along with other excerpts from the USACE report are provided in Appendix 1. The report stated that a Sediment Impact Assessment Model (SIAM) could be developed to assess the feasibility of the alternatives. Concluding remarks endorsed the feasibility study including the SIAM assessment. The USACE released the findings of the feasibility study at the 2 nd Federal Joint Interagency Conference in The report, SIAM Case Study: Kankakee River Basins, Indiana and Illinois, expounds on the data sources used in the analysis and provides numerical representations of the impacts of five alternatives seeking to decrease the sediment load to the Illinois River; the SIAM case study is provided in Appendix 2. An estimate of 37,000 tons per year of sediment supply was listed for the entire Yellow River watershed. An additional 24,000 tons per year of sediment supply was included due to the eroding streambanks along the channel. The SIAM assessment suggested that the existing total sediment load within the channel is approximately 55,900 tons per year at a point located near the middle of the main stem, and 72,100 tons per year at the mouth of the river. The report concluded that the sediment load within the Kankakee River is relatively insensitive to the bank erosion contribution from the Yellow River. Further work is proposed for improving the estimates of the sediment sources and suggestions are made to place an emphasis on the Yellow River basin. The report also recommends that the SIAM model be extended to more thoroughly assess the impact of potential mitigation projects along the Yellow River. Christopher B. Burke Engineering, LLC 6

9 2.0 Objectives 2.1 Remediation Project Development The primary objective of this study is to provide schematic designs for three representative sites along the Yellow River within Starke County, Indiana. Mitigation measures required along the channel should address the steep streambanks and mass failures that are occurring. The rehabilitation features should also be tailored to reduce the erosion occurring within the channel, reducing the overall sediment contribution from the Yellow River to the Kankakee River. CBBEL developed an analysis program consisting of concurrent data gathering and schematic design phases. The analysis program consists of the following tasks: Review of Existing Files and Data Assessment of Current River Condition Project Site Identification Design Discharge Determination Specific Gage Analysis Grade Control Assessment Bank Stabilization Treatment Assessment 2.2 Road Map Consideration The second objective of this study is to provide a Road Map for long-term mitigation. The road map for mitigation must include consideration of the overall goal of reducing the downstream sediment loading without causing other, unintended and negative consequences. To help guide future work, the following tasks were completed: Meander Belt Delineation Equilibrium Slope Assessment Consideration Stream Monitoring Program Consideration Christopher B. Burke Engineering, LLC 7

10 3.0 Existing Conditions 3.1 Yellow River Description The Yellow River is a low energy (low flow velocity), perennial river, meaning flow within the river is constant throughout the year except during periods of extreme drought. The hydrology and hydraulics of the river system have been significantly altered over the past 200 years, resulting in physical responses from the river. One response has been erosion of the channel bed and banks due to increased flow frequency and velocity and associated increases in sediment capacity. A consequence of the increased sediment capacity is the river carries a large sediment load, transporting the material to downstream locations along the Kankakee and Illinois rivers. This increased erosion along with the land uses in the overbank areas have led to instabilities in the channel banks. Upstream segments of the river system are degrading, or developing steeper stream profiles. Downstream segments (including the Kankakee and Illinois rivers) are aggrading, or decreasing stream gradients, as a result of the increased sediment supply from upstream. This decreasing stream gradient compounds the amount of aggradation because of decreased sediment transport capacity. The following are key issues: Streambanks Steep slopes exist along much of the Yellow River through Starke County. Aerial topography data shows the bank slopes exceed 2H:1V (horizontal : vertical) in many locations, including several locations with slopes exceeding a 1H:1V and bank heights of greater than 20 feet. The steep gradients are unstable resulting in bank failures caused by erosion of the bank toe. The gradations provided by previous studies indicate the material forming the channel is made up of non-cohesive, fine to medium sands. These materials generally have low shear strengths, and are unable to maintain the high bank angles present along the Yellow River. The low-strength bank material also has a high propensity for erosion, especially at the toe. Undercut bank toes lead to sloughing and slope failures. Bank failures generally continue to occur until the failed bank material accumulates in adequate amounts to reinforce the toe, or create a more stable bank angle. Aerial photography and photographs taken along the channel show a considerable number of trees that have fallen into the channel as a result of bank failures, and weakened bank segments. Selected site photographs are provided in Appendix 3. While the presence of large woody debris within the channel can promote habitat development and healthy morphological change, the amount of material appears to be beyond a natural level as a result of the significant and ongoing erosion along the river. Eddy currents and increased turbulence in the flow create greater scour depths in the immediate vicinity of the obstructions. This phenomenon often leads to more erosion along the toe of the bank and more instability. Christopher B. Burke Engineering, LLC 8

11 3.1.2 Sediment Supply Previous studies have determined that sediment supply to the Yellow River is composed of point sources and non-point sources. The dominant agricultural land use results in upland erosion and the supply of sediment into the river system. Based on the estimates in the 2010 USACE SIAM case study, the type of land use and inconsistent use of BMPs has caused the non-point supply of sediment to be approximately sixty percent of the total supply into the Yellow River. Alternative 2 of the USACE study suggests that eliminating the upland sediment supply would allow for a reduction of wash load that persists all the way to the Illinois River. The most evident point source of sediment supply is the frequent bank failures along the channel. A 100-percent efficient delivery of sediment is achieved as this material is deposited directly into the river-body. Although the 2010 USACE SIAM case study suggests the overall influence of the bank failures on the sediment yield to the Kankakee River is negligible, the bank failures lead to other detrimental occurrences, as mentioned previously. The fine sediments forming the channel are another major source of sediment supply. Though the source is internal to the stream, the impact of highly erodible bed and bank materials is significant. The conclusions of previous studies suggest that any reduction of sediment from the point and non-point sources would result in increased mobility of sediment (erosion) from within the channel, thus leaving the sediment yield to downstream segments largely unchanged. Christopher B. Burke Engineering, LLC 9

12 4.0 Schematic Design 4.1 Project Site Identification The locations for potential pilot mitigation projects were selected based on general direction from the 3-County Drainage Board and observations of serious channel instability. As mentioned previously, the main objectives of the rehabilitation projects are the stabilization of the streambanks and the reduction of excessive erosion. Additional criteria extracted from the major objectives are: The site shall be chosen to reduce the risk to human life and property created by the steep slopes or potential for future river migration The site shall present a suitable example of the effectiveness of the design for beneficial use in future projects The site shall be selected to maximize the amount of life and property protected and to minimize the extent of the site size, rehabilitation scope, and project cost. Three different sites were selected. Project Site #1 is located north of State Road 8 at County Road 700 E and extends approximately 3,150 feet east, along the river. The site was selected to protect the homes north of State Road 8, as well as to prevent the migration of the river toward County Road 700 E. This segment of the river shows evidence of bank slopes in excess of 2H:1V. The schematic layout for the mitigation site is provided as Exhibit 2. A steep bluff located along a sharp meander west of the State Road 23 bridge crossing was selected as Project Site #2, which begins 650 feet downstream of the bridge and continues for another 800 feet along the river. The migrating stream has created a steep slope along the outside of the river bend which has slopes up to 1H:1.5V. The bluff has a maximum bank height of 40 feet, posing an immediate hazard and potential threat to the homes located south and west of the channel. Exhibit 3 depicts a schematic layout of the project site. Project Site #3 is located immediately west of County Line Road near the border between Starke and Marshall Counties. The site begins 100 feet downstream of the bridge and extends an additional 1,200 feet downstream. A large bluff has formed on the outside of a bend in the river, with a maximum bank height of approximately 20 feet with slopes reaching 1H:1.75V. The channel has migrated to a location within approximately 25 feet of a home on the south side of the river. A schematic layout of the site is provided as Exhibit 4. The development of the schematic design for all sites is explained in the following sections. The discussion includes determination of design parameters as well as consideration given to mitigation measures. 4.2 Design Discharge Determination Unlike many hydrologic and hydraulic design scenarios, the determination of design parameters for stream rehabilitation / restoration projects is not typically based on a level of annual risk. Designs focusing on morphological process must consider the stream discharge which is most heavily associated with the formation of the channel. Christopher B. Burke Engineering, LLC 10

13 The most common design discharges used for projects of this type are the effective discharge, 2-year recurrence interval discharge, and the bankfull discharge. The effective discharge is defined as the discharge that is statistically responsible for moving the most sediment within a given year. The 2-year discharge is defined as the event that has an annual-percent-chance of occurrence of 50%, as determined by a statistical evaluation of gage records. Finally, the bankfull discharge is characterized by the flow that is associated with the stream flowing full and is determined by a thorough investigation of the project site and is dependent upon observed high water marks and changes in vegetation type and density. Available data from multiple studies were compiled to complete an effective discharge evaluation. Streamflow data from the USGS stream gage at Knox, IN was used to develop the statistical relationship for discharges along the Yellow River. Flow characteristics for the channel were extracted from a HEC-RAS model provided by the IDNR, which was developed for the 1988 Wide Levee Project. Bed material data was taken from the 1992 CBBEL study of the Kankakee and Yellow river basins. Sediment transport through the system was simulated using the Brownlie sediment transport model developed for determining the total load for sand bed channels. The USGS stream gage at Knox, IN was also used to estimate the 2-year recurrence interval flow rate. The peak annual flow rates were analyzed to calculate the 2-year flow rate of 2,400 cubic feet per second (cfs). The bankfull discharge for each project location was calculated by inspection of the HEC-RAS cross-sections near each project site. The cross-sections were examined for obvious overflow stages and the resulting top width was then compared to the aerial photographs to detect obvious discrepancies. Model simulations were completed until the flow rate corresponding to the overflow stage was determined. The estimated effective, 2-year, and bankfull discharges are shown in Table 1. Table 1: Design Discharge Comparison Project Site Number Effective Discharge (cfs) 2-year RI Discharge (cfs) Bankfull Discharge (cfs) As presented in Table 1, the range of design discharges is rather large with the effective discharge considerably less than the other two estimates. This is not unreasonable since the presence of fine sediment forming the channel suggests that even minimal flow rates within the channel will mobilize channel material. Noting this fact, the design discharge should be skewed toward the more frequent, less extreme flow rates. Bankfull discharge determination is a subjective process and without a thorough inspection of the individual sites, the flow rates shown in Table 1 are a rough estimate at best. Considering the fine sediment in the channel, the 2- year recurrence interval discharge should be expected to be a high estimate for all three sites. Therefore, the most reasonable design discharge for natural channel processes for this project evaluation is the effective discharge. Christopher B. Burke Engineering, LLC 11

14 One benefit of using the effective discharge method is that the process provides an estimate of the annual sediment yield of the stream from the location at which the analysis is performed. The model used to obtain information for the analysis is outdated and may not adequately represent the hydraulic performance of the river in its current form and condition. However, it is sufficient to develop the schematic designs for this report. The sediment yield estimates provided in Appendix 4 refer to the sediment yield only from the individual sites and do not account for additional material from upstream sources that may be deposited along the channel. A comparison of sediment yields to previous studies is not valid. Features within a channel that are required to remain in place should be designed for more extreme events than the morphologic design event (effective discharge, in this case). The morphologic design event is typically used to design an unarmored channel that will be allowed to migrate naturally. Armoring systems need to withstand much more extreme events and are more appropriately designed using a risk based assessment of discharge. For the proposed project sites, the 1%-annualchance event was used to design the armoring systems. The maximum velocities and shear stresses in the channel, shown in Table 2, are based on the results of the IDNR HEC-RAS model and the listed 1%-annual-chance event flow rate of 5,000 cfs. The maximum values calculated are relatively low in terms of performance limits of available mitigation measures. Table 2: Maximum Velocity and Shear Stress Project Site Number Maximum Velocity (ft/s) Maximum Shear Stress (lbs) 4.3 Specific Gage Analysis River systems with large amounts of sediment supply and yield often have aggradational or degradational trends. It is important that the channel achieves vertical stability prior to constructing bank stabilization projects. Vertical stability occurs when there is negligible aggradation or degradation. One method of determining the trend to vertical change within the channel is by performing a specific gage analysis. A specific gage analysis compares the gage height reading from a single gage for the same discharge over a number of years. An aggradational trend would be suggested if the gage height increases in time, and a degradational trend would be inferred from a decreasing gage height over time. Significant aggradational or degradational trends could lead to the destabilization of the mitigation measured installed. Naturally established vertical stability, or forced stability by human intervention must occur to promote the integrity of the installed features. The USGS stream gage at Knox, IN has a record that begins in 1943 and continuing to the present date. Gage heights are only provided for the peak flows of each year, providing a limited amount of data points to analyze. A specific gage analysis of the record suggests that the channel has remained relatively stable in the vertical direction; however, the gage is not located very near to the potential project sites. Christopher B. Burke Engineering, LLC 12

15 As a result of the limited dataset and the remote location of the gage relative to the project sites, the installation of grade control structures should be included in the design of all potential sites to encourage the stability of the channel and increase the longevity of the mitigation measures. 4.4 Grade Control In addition to stabilizing the channel bed, grade control can also be used to modify the amount of stream power generated by a stream. The stream power available to move sediment through the channel is proportionally decreased by a decrease in the gradient of a river. However, the use of one or more grade control structures to decrease the river gradient has additional impacts to the channel. These impacts are addressed in Section 7.4. The type and details of a grade control structure are dependent on the intended purpose of the structure. All grade control structures should incorporate a stilling basin to dissipate the energy of the water spilling over the crest, helping to minimize erosion and undercutting of the structure. Stilling basins for grade control structures that are intended to stabilize the vertical profile of the channel and / or prevent head-cutting through a reach should be designed such that the elevation and profile of the basin can adjust to the changing downstream channel elevation. This can often be accommodated by use of a simple riprap stilling basin that is flexible and capable of taking on the changing shape of the downstream channel without compromising protection of the grade control structure. Grade control structures that are intended to decrease the river gradient require a slightly different type of stilling basin. These structures are designed for a particular channel gradient, and therefore do not need to be flexible. More rigid types of stilling basins, or energy dissipaters, can be used. Rigid structures may include concrete stilling basins or sills to prevent any substantial displacement of material downstream of the grade control structure. To more adequately facilitate the possible long-term remediation approaches developed in the future Road Map, a flexible type of stilling basin should be used for ease of modification if needed in the future. The grade control structure itself must also be able to be adjusted, rather than having to be removed if the river profile does not meet the design requirements of future projects. This can be achieved by using a sheet pile wall as a grade control structure and protecting the structure with a riprap basin. Christopher B. Burke Engineering, LLC 13

16 4.5 Bank Stabilization Treatments A wide range of bank stabilization techniques exists which address an equally diverse set of bank stability issues. Types and uses of bank stabilization treatments are tailored to address specific weaknesses in channel banks. The types of treatments that are most applicable to the needs of the physical system can be classified into the following categories: Vegetation - The use of vegetation for bank stabilization should be limited to low gradient, vertically stable and non-incising channels where proper growing conditions exist, as defined by a plant specialist. Bioengineering Measures - Bioengineering measures may be used in low to moderate gradient streams where existing bank material supports the growth of woody vegetation. Supplementary or alternative mitigating measures may be required on banks with heavy surface drainage, on the outsides of meander bends and other high-velocity areas of the channel, and on slopes subject to shallow mass movements. Rigid structures - Rigid toe protection is most effectively utilized in actively incising stream channels, in areas of flow concentration such as in the vicinity of hydraulic structures, and in areas where the primary flow directly impinges on the stream banks. Additional explanation of the types and applications of common bank stabilization techniques are provided in Appendix 6. Stabilization treatments have been selected for specific segments of each project site. The types of treatments and locations of use for Project Site #1 (Exhibit 2) are detailed in Table 3. Table 3: Project Site #1 Stabilization Treatments Approximate Station Left Bank 1 Treatment Method Right Bank 1 Treatment Method 0+00 to 1+20 None None 1+20 Grade control structure 1+20 to 2+20 None None 2+20 to 9+20 Install Geoweb wall (2 ft - 6 ft) 2, 3 None 9+20 to Natural fiber roll w/ 3H:1V slopes None to Natural fiber roll w/ 3H:1V slopes Natural fiber roll w/ 3H:1V slopes to Install Geoweb wall (3 ft - 7 ft) 2, 3 Natural fiber roll w/ 3H:1V slopes 1 Banks identified while facing downstream. 2 Height of wall measured above channel bed elevation. 3 3H:1V slopes above Geoweb wall; slopes protected w/ TRM to 1%-annual-chance water surface elevation + 2 ft Christopher B. Burke Engineering, LLC 14

17 Project Site #2 (Exhibit 3) incorporates some of the same treatment types as Project Site #1. However, the height of the bluff and proximity to homes requires significantly taller walls for a large portion of the treatment length. The stabilization treatments proposed for Project Site #2 are shown in Table 4. Table 4: Project Site #2 Stabilization Treatments Approximate Station Left Bank 1 Treatment Method Right Bank 1 Treatment Method 0+00 to 1+17 None None 1+17 Grade control structure 1+17 to 8+73 Install Geoweb wall (2 ft - 11 ft) 2, 3 None 1 Banks identified while facing downstream. 2 Height of wall measured above channel bed elevation. 3 3H:1V slopes above Geoweb wall; slopes protected w/ TRM to 1%-annual-chance water surface elevation + 2 ft The similarities between Project Site #2 and #3 (Exhibit 4) allow for near identical treatment types. The home near the top of the bluff will not permit safe installation of any of the available treatment types without being removed from the site. It is recommended that the residence and all outbuildings be removed from the site, allowing for the regrading of the area. The removal of the structures also reduces the risk of personal injury due to a slip or fall on the Geoweb wall. Table 5 shows the treatment types suggested for Project Site #3. Table 5: Project Site #3 Stabilization Treatments Approximate Station Left Bank 1 Treatment Method Right Bank 1 Treatment Method 0+00 to 0+75 None None 0+75 Grade control structure 0+75 to 9+43 Install Geoweb wall (2 ft - 11 ft) 2, 3 None 9+43 to Natural fiber roll w/ 3H:1V slopes None 1 Banks identified while facing downstream. 2 Height of wall measured above channel bed elevation. 3 3H:1V slopes above Geoweb wall; slopes protected w/ TRM to 1%-annual-chance water surface elevation + 2 ft Christopher B. Burke Engineering, LLC 15

18 5.0 Conceptual Opinions of Probable Cost 5.1 Stream Stabilization Construction Costs Conceptual opinions of probable cost for each project site, along with alternatives, were also prepared. The estimated costs are based on the schematic layout for each site as discussed in Section 4.0. A more detailed breakdown of the estimated project costs shown in Table 6 is provided in Appendix 7. All three potential rehabilitation sites will require a significant effort to develop the necessary information for permitting and development of construction drawings, which contributes substantially to the expected total project costs. Table 6: Opinion of Probable Cost for Project Sites Improvement Item Conceptual Opinion of Probable Cost Project Site #1 Project Site #2 Project Site #3 Demolition $93,000 $44,000 $117,000 Bank Stabilization Improvements $385,400 $351,200 $264,200 Channel Grade Control $104,200 $115,000 $126,300 Site Restoration $61,200 $26,300 $20,400 Miscellaneous Items and Contingency $196,500 $163,800 $161,100 SUBTOTAL CONSTRUCTION COST $840,300 $700,300 $689,000 Subtotal Site and River Topographic Survey $42,100 $35,100 $34,500 Subtotal Engineering Design $168,100 $140,100 $137,800 Subtotal Construction Observation $42,100 $35,100 $34,500 TOTAL PROJECT COST $1,092,600 $910,600 $895, Potential Cost Considerations The initial construction of one or more of the project sites will constitute the majority of the total expenses associated with rehabilitation of the river segments. However, additional costs may be realized to maintain the installed infrastructure and to promote the longevity of the materials Maintenance The establishment and maintenance of vegetative cover of the sloped portions of the streambanks is critical to preventing bank erosion and subsequent migration. Should vegetation initially fail to be established, additional planting/sewing and fertilizing will be necessary. The development of bare spots on the banks should be monitored and addressed by immediate revegetation. Grasses and other non-woody vegetation may be groomed on a regular basis, but maintaining the banks in a well-manicured condition is not necessary. Trimming the vegetation too short or burning excessive growth should be avoided to help decrease the possibility of cover loss. Christopher B. Burke Engineering, LLC 16

19 Monitoring vegetal establishment and growth should occur on a regular basis immediately after completion of the rehabilitation. The frequency of monitoring may decrease as ground cover develops. Stabilized banks should be inspected following high-flow events to determine if mitigation components have been displaced. Any defective armoring systems should be repaired or replaced immediately to prevent compromising the stability of the surrounding bank Project Longevity Sand-bed rivers like the Yellow River naturally meander, adjusting their planform and cross-sectional geometry in order to reach a state of equilibrium with water and sediment inputs. Confining the channel to a static alignment is an unnatural practice. However, with adequate monitoring, maintenance, and adjustment of land use practices, it is often possible to achieve a static channel with the help of armoring systems. The expected longevity of the proposed armoring systems will depend heavily on the monitoring and maintenance performed immediately after construction until the disturbed areas can be fully vegetated. After this point, it is likely that the components will provide the intended service for an indefinite amount of time. The lifespan of the stabilization measures is highly dependent upon the proper maintenance of damaged or missing components. Given the low velocities and shear stresses expected in the channel, the risk of material failure is expected to be low. Large floating debris poses a tangible risk to the structural integrity of the systems. However, with proper maintenance, the damaged portions can be repaired or replaced to reinstate the previous level of protection. Christopher B. Burke Engineering, LLC 17

20 6.0 Road Map Considerations 6.1 Meander Belt Delineation The Yellow River has historically been a highly sinuous channel, even transitioning to a braided channel in areas, prior to human intervention. Changes in channel alignments and land use practices have likely increased the magnitude and volume of flow through the channel as well as having increased the number of encroachments on the floodplain. The floodplain of the existing channel provides important ecological and morphological functions. Healthy stream corridors incorporate an active floodplain which can serve as pollutant filtration, energy dissipation during high-flow events, sediment storage, as well as allowing for rejuvenation of the channel through natural channel modification of planform and cross-sectional geometry. In order to develop a more natural stream corridor capable of providing such benefits, setbacks from the channel are often necessary. These setbacks can be appropriately determined by evaluating the approximate width of the streamway, or meander belt, for sinuous channels. The Natural Resource Conservation Service (NRCS) has set forth relationships for determining the approximate meander belt width for a channel based on the contributing drainage area. These relationships have been developed by observation of a large number of healthy river corridors. The relationships are used to determine a base approximation of the meander belt width, and must be tempered with other available data. In order to more appropriately size the meander belt width, existence of remnant channels must be considered, as well as the presence of floodplain areas that extend beyond the base approximation. These areas are signals of where the channel once was, and suggest where the channel may migrate in the future. The base approximation of the meander belt was calculated by using the USGS drainage area information and the NRCS regression relationship shown in Appendix 8. Using soil maps and aerial photographs of the areas adjacent to the river, a layout of the meander belt width for the main stem of the Yellow River was developed through Starke County. The meander belt has widths ranging from 1,600 feet to 3,500 feet. Exhibit 5 shows the meander belt through Starke County. Meander belt determination calculations and details can be found in Appendix 8. The land area within the meander belt ideally contains little to no development, thus allowing the stream to migrate without endangering human life or established infrastructure. When utilized appropriately, stream setbacks can help to create, or maintain, a state of dynamic equilibrium. In addition to enforcing setbacks, reduction of surface runoff from paved areas in the watershed, and limiting the sediment supply from the watershed to predevelopment levels are also necessary to allow the channel to re-establish a state of dynamic equilibrium. 6.2 Equilibrium Slope Assessment As suggested in Section 4.4, the gradient of the channel can be modified to assist in decreasing the amount of sediment delivered to downstream reaches of the Yellow River, as well as the Kankakee and Illinois rivers. An equilibrium slope assessment Christopher B. Burke Engineering, LLC 18

21 would be necessary to determine the channel slope necessary to limit the sediment yield of the system to a target level. Throughout Starke County, the river appears to be fully alluvial, that is, the channel is capable of fulfilling its sediment transport capacity. It is because of this fact that the sediment yield from the channel is likely not equivalent to the sediment supply to the channel. This imbalance has lead to mass erosion of the banks and degradation of the streambed in portions of the channel. An improved understanding of the magnitude of sediment supply from the watershed, including an assessment of watershed land use practices, would also be necessary to help determine a realistic approximation of the sediment supply to the system, and thus the most reasonable target sediment yield. Aggradational or degradational trends could develop without a realistic target yield. An equilibrium slope assessment typically includes the development of sediment rating curves for a discrete supply and study reach, which are often limited to small segments of rivers. Numerous analyses would be required to develop a prudent layout for a series of grade control structures along the entire main stem of the Yellow River. These analyses would require a detailed topographic survey of the entire study reach to properly account for the affect of the channel geometry on sediment transport processes. 6.3 Stream Monitoring Program A lack of substantial sediment transport related data for the Yellow River is evident based on the review of previous studies, development of the proposed schematic designs, and a general survey of available data. The studies that have been performed have often employed very limited datasets, or have simply made assumptions about the amount of sediment supplied to the Yellow River. Knowledge of the quantity of sediment being transported through the river is paramount for informed design of current and future mitigation measures, assessment of mitigation project benefits, proof of sediment supply to the Kankakee River, and identification of problem areas within the channel. Currently, there are no sediment gaging sites along the river. Erosion mitigation and bank stabilization measures must consider the amount of sediment being supplied from the immediate upstream area to help prevent significant aggradation or degradation. Without having accurate data, the longevity of the constructed measures may be severely decreased. The addition of a sediment monitoring station at one, or several locations along the river would be capable of providing ample data. This data could then be used to help determine the overall impact of constructed measures and, over time, suggest the most beneficial and cost effective measures specific to the Yellow River. The implementation of a sediment monitoring program would allow the 3-County Drainage Board and Kankakee River Basin Commission to quantitatively assess the Yellow River s impact on the Kankakee River. The accurate depiction of sediment supply could also aid in the design of mitigation measures along the Kankakee River. The extent of the monitoring program established should be determined by the length over which stream rehabilitation projects are expected to occur. The extent of stream monitoring should be inclusive of all project sites, being able to provide Christopher B. Burke Engineering, LLC 19

22 sediment data for both the upstream and downstream reaches proximate to each site. Multiple gages will be necessary to gain the full benefit of the monitoring program. It is recommended that USGS gages be installed at multiple locations along Yellow River to provide data needed to evaluate rehabilitation projects. Based on this preliminary investigation, the proposed gage locations are shown on Exhibit 6. In addition to monitoring the sediment conveyed by the Yellow River, regular field inspection of completed projects is essential for project success. Inspection of installed mitigation measures can help to suggest the most applicable means of providing the desired outcome of future projects. Regular inspection can also help to prevent failure of constructed projects. As discussed previously, rivers are naturally dynamic and exhibit near-constant change. By assessing the condition of installed features regularly, the recovery or decline of a stream segment can be detected, providing feedback on the quality and effectiveness of previous designs. 6.4 Tree Maintenance Program The 3-County Drainage Board is currently carrying out a project to remove several logjams within both the Yellow and Kankakee Rivers. These logjams formed after severe storms and high winds passed through the area in June of The formation of these logjams and the efforts taken to acquire disaster-aid monies to have the logjams removed highlight an ongoing problem along the Yellow and Kankakee Rivers. Due to the nature of the soils in the area, trees in the stream banks or along the top of the stream banks are susceptible to toppling and falling in the streams. When this occurs, sediment associated with the tree root wad is deposited in the stream, the immediate area of the tree root location is vulnerable to increased erosion, and the fallen tree causes deflection of the stream current around and under the fallen tree. To decrease the frequency of these situations in the future, it is recommended that the 3-County Drainage Board establish an ongoing tree maintenance plan for the entire reaches of the Yellow and Kankakee Rivers within their jurisdiction. The Tree Maintenance Plan should include descriptions of situations when a leaning tree will be removed, standard specifications for tree/logjam removal and disposal and recommended tree, shrub and grass planting measures for areas requiring revegetation. Establishment of a Tree Maintenance Plan should be discussed with state and federal regulatory personnel so that tree removal can be accomplished with only minor permitting efforts or without the need for regulatory permits entirely. Representatives of Marshall County should also be contacted to participate so tree maintenance becomes as comprehensive as possible. Christopher B. Burke Engineering, LLC 20

23 Where desirable, removed trees may be replaced with native species more acclimated to the soil and hydrologic conditions present along the Yellow and Kankakee Rivers. Suggested tree and shrub species are: Scientific Name Common Name Type Aronia prunifolia Purple Chokeberry Medium Shrub Betula nigra River Birch Small Canopy Tree Cornus sericea Red Osier Dogwood Medium Shrub Physocarpus opulifolius Common Ninebark Small Shrub Populus tremuloides Quaking Aspen Small Canopy Tree Quercus macrocarpa Bur Oak Large Canopy Tree Quercus palustris Pin Oak Small Canopy Tree Salix amygdaloides Peach Leaf Willow Small Canopy Tree Tilia Americana Basswood Large Canopy Tree Christopher B. Burke Engineering, LLC 21