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From page 57... ... 57 3.1 Overview and Selection of Treatments for Testing 3.1.1 Overview As noted in Section 2.6.1, a wealth of literature and documentation is available regarding environmentally sensitive stream bank protection measures. However, most of the information regarding biotechnical measures is composed of case studies of particular sites that have, in many cases, limited general applicability. Read the entire page →
From page 58... ... 58 Evaluation and Assessment of Environmentally Sensitive Stream Bank Protection Measures • Quantitative measurements of key hydraulic variables, and • Condition monitoring of each component before testing and after each test flow event. The two biotechnical bank-protection treatments suggested to, and approved by, the NCHRP Project 24-39 panel for testing were: 1. Read the entire page →
From page 59... ... Testing and Appraisal of Testing Results 59 Figure 3.2 shows native Salix exigua at a local site in Fort Collins, Colorado, from which the cuttings for the test installations were obtained. The two treatments described above, including planter box (tray) Read the entire page →
From page 60... ... 60 Evaluation and Assessment of Environmentally Sensitive Stream Bank Protection Measures LIVE SILTATION 1.5 ft 1 ft Live siltaon willows Live willow stakes through coir mat Live stakes Live siltation willows with stone toe Figure 3.3. Live siltation with live staking and stone toe. Read the entire page →
From page 61... ... Testing and Appraisal of Testing Results 61 in the testing flume. To keep Task 7 testing within the constraints of the planned budget the VMSE treatment was installed in an existing 12-in. Read the entire page →
From page 62... ... 62 Evaluation and Assessment of Environmentally Sensitive Stream Bank Protection Measures dation for plant-growth needs more difficult to achieve. Furthermore, vegetation can be grown successfully in compacted soil under less-than-ideal conditions provided certain limits and precautions are observed. Read the entire page →
From page 63... ... Testing and Appraisal of Testing Results 63 Several of the research opportunities that were addressed, at least in part, by the two treatments selected for testing under NCHRP Project 24-39 are summarized below: Live Siltation -- Research into velocities that this technique can withstand would be helpful. Live Staking -- Studies would be valuable regarding the effect live staking has on increasing the ability of other measures to withstand higher velocities and shear stresses. Read the entire page →
From page 64... ... 64 Evaluation and Assessment of Environmentally Sensitive Stream Bank Protection Measures 7. Both Trays 1 and 2 were outfitted with substantial drainage ports in the bottom to allow for proper soil drainage. Read the entire page →
From page 65... ... Testing and Appraisal of Testing Results 65 determination and Table 3.1 presents the results of oven-dried weights of the biomass of the various above-ground and below-ground components. Read the entire page →
From page 66... ... 66 Evaluation and Assessment of Environmentally Sensitive Stream Bank Protection Measures 14. Between the top edge of each tray and the opposite flume wall, metal flashing was used to seal the gap between the tray and the wall. Read the entire page →
From page 67... ... Testing and Appraisal of Testing Results 67 b) An intermediate flow rate of 100 cfs which just reached the top of the stream bank; and c) Read the entire page →
From page 68... ... 68 Evaluation and Assessment of Environmentally Sensitive Stream Bank Protection Measures is provided below, and Figure 3.10 provides photographs of the tests in progress. Discussion of the data analyses and results is provided in Section 3.5. Read the entire page →
From page 69... ... Testing and Appraisal of Testing Results 69 Test 5 was conducted on September 9, 2014 with a discharge of 100 cfs. Duration of the test was 4 hours. Read the entire page →
From page 70... ... 70 Evaluation and Assessment of Environmentally Sensitive Stream Bank Protection Measures Test 6 was conducted on September 11, 2014 at a discharge of 150 cfs for a duration of 4 hours. The stoplogs used in Test 5 were left in place for Test 6. Read the entire page →
From page 71... ... Testing and Appraisal of Testing Results 71 93 94 95 96 97 98 99 100 0 5 10 15 20 25 30 35 40 El ev a on , Distance, Obs WSEL, 50 cfs Obs WSEL, 100 cfs Obs WSEL, 150 cfs Pred. WSEL 50, n = 0.035 Pred WSEL 100, n = 0.035 Pred WSEL 150, n = 0.030 Bed Approach (arficial roughness) Read the entire page →
From page 72... ... 72 Evaluation and Assessment of Environmentally Sensitive Stream Bank Protection Measures the soil lifts in Tray 2, as well as the irregular slope geometry due to the stair-step configuration of the lifts. Table 3.2 provides a summary of the HEC-RAS calibration runs on the vegetative treatments in Trays 1 and 2. Read the entire page →
From page 73... ... Testing and Appraisal of Testing Results 73 CROSS SECTION 4 TRAY 1 TRAY 2 TEST 1: 50 ft3/s TEST 4: 50 ft3/s TEST 2: 100 ft3/s TEST 5: 100 ft3/s TEST 3: 150 ft3/s TEST 6: 150 ft3/s 0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 Distance across cross section, ft El ev at io n, ft 0 1 2 3 4 5 6 7 8 2 3 4 5 6 7 Distance across cross section, ft El ev at io n, ft 50 ft3/s50 ft3/s 0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 Distance across cross section, ft El ev at io n, ft 0 1 2 3 4 5 6 7 8 2 3 4 5 6 7 Distance across cross section, ft El ev at io n, ft 0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 Distance across cross section, ft El ev at io n, ft 0 1 2 3 4 5 6 7 8 2 3 4 5 6 7 Distance across cross section, ft El ev at io n, ft 150 ft3/s 100 ft3/s100 ft3/s 150 ft3/s Figure 3.13. Velocity contours at Cross Section 4, Trays 1 and 2. Read the entire page →
From page 74... ... 74 Evaluation and Assessment of Environmentally Sensitive Stream Bank Protection Measures CROSS SECTION 8 TRAY 1 TRAY 2 TEST 1: 50 ft3/s TEST 4: 50 ft3/s TEST 2: 100 ft3/s TEST 5: 100 ft3/s TEST 3: 150 ft3/s TEST 6: 150 ft3/s Distance across cross section, ft El ev at io n, ft NO DATA 0 1 2 3 4 5 6 7 8 2 3 4 5 6 7 Distance across cross section, ft El ev at io n, ft 0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 Distance across cross section, ft El ev at io n, ft 0 1 2 3 4 5 6 7 8 2 3 4 5 6 7 Distance across cross section, ft El ev at io n, ft 0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 Distance across cross section, ft El ev at io n, ft 0 1 2 3 4 5 6 7 8 2 3 4 5 6 7 Distance across cross section, ft El ev at io n, ft 50 ft3/s 150 ft3/s 100 ft3/s 50 ft3/s 150 ft3/s 100 ft3/s Figure 3.14. Velocity contours at Cross Section 8, Trays 1 and 2. Read the entire page →
From page 75... ... Testing and Appraisal of Testing Results 75 CROSS SECTION 12 TRAY 1 TRAY 2 TEST 1: 50 ft3/s TEST 4: 50 ft3/s TEST 2: 100 ft3/s TEST 5: 100 ft3/s TEST 3: 150 ft3/s TEST 6: 150 ft3/s Distance across cross section, ft El ev at io n, ft 0 1 2 3 4 5 6 7 8 2 3 4 5 6 7 Distance across cross section, ft El ev at io n, ft 0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 Distance across cross section, ft El ev at io n, ft Distance across cross section, ft El ev at io n, ft Distance across cross section, ft El ev at io n, ft Distance across cross section, ft El ev at io n, ft 50 ft3/s 150 ft3/s 100 ft3/s 50 ft3/s 150 ft3/s 100 ft3/s Figure 3.15. Velocity contours at Cross Section 12, Trays 1 and 2. Read the entire page →
From page 76... ... 76 Evaluation and Assessment of Environmentally Sensitive Stream Bank Protection Measures CROSS SECTION 16 TRAY 1 TRAY 2 TEST 1: 50 ft3/s TEST 4: 50 ft3/s TEST 2: 100 ft3/s TEST 4: 100 ft3/s TEST 3: 150 ft3/s TEST 6: 150 ft3/s 0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 Distance across cross section, ft El ev at io n, ft 0 1 2 3 4 5 6 7 8 2 3 4 5 6 7 Distance across cross section, ft El ev at io n, ft 0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 Distance across cross section, ft El ev at io n, ft 0 1 2 3 4 5 6 7 8 2 3 4 5 6 7 Distance across cross section, ft El ev at io n, ft 0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 Distance across cross section, ft El ev at io n, ft 0 1 2 3 4 5 6 7 8 2 3 4 5 6 7 Distance across cross section, ft El ev at io n, ft 50 ft3/s 150 ft3/s 100 ft3/s 50 ft3/s 150 ft3/s 100 ft3/s Figure 3.16. Velocity contours at Cross Section 16, Trays 1 and 2. Read the entire page →
From page 77... ... Testing and Appraisal of Testing Results 77 flows (100 and 150 cfs) , although the live siltation willows near the toe of the slope in Tray 1 were more effective at producing this condition. Read the entire page →
From page 78... ... 78 Evaluation and Assessment of Environmentally Sensitive Stream Bank Protection Measures Tray 1, Test 1 (50 ft3/s) Read the entire page →
From page 79... ... Testing and Appraisal of Testing Results 79 Tray 2, Test 5 (100 ft3/s) 0 2 4 6 8 10 12 14 16 18 20 -8 -6 -4 -2 0 Riprap stream bed Metal flashing D is ta nc e a cr o ss fl u m e , ft Distance along flume, ft Flow Figure 3.18. Read the entire page →
From page 80... ... 80 Evaluation and Assessment of Environmentally Sensitive Stream Bank Protection Measures Discharge, ft3/s Typical Range of Bed Shear Stress, lb/ft2 Minimum Bed Shear Stress, lb/ft2 Maximum Bed Shear Stress, lb/ft2 TRAY 1 50 0.50 to 0.75 ~ 0.25 ~ 1.00 100 1.50 to 2.00 ~ 1.00 ~ 2.25 150 1.50 to 2.00 ~ 1.25 ~ 2.25 TRAY 2 50 1.25 to 2.00 ~ 1.00 ~ 2.25 100 1.75 to 3.00 ~ 1.00 ~ 3.50 150 2.50 to 4.00 ~ 1.75 ~ 4.50 Table 3.3. Results of bed shear stress analyses. Read the entire page →
From page 81... ... Testing and Appraisal of Testing Results 81 Tray 1, Test 2 (100 ft3/s) Read the entire page →
From page 82... ... 82 Evaluation and Assessment of Environmentally Sensitive Stream Bank Protection Measures as are the areas of metal flashing at the top of the slope. Because no erosion occurred on areas of riprap or metal flashing, the contoured portion of the figure is blanked out in these areas. Read the entire page →
From page 83... ... Testing and Appraisal of Testing Results 83 3.6 Appraisal of Testing Results The quantitative analyses of velocity, shear stress, and erosion data presented in the previous sections support the qualitative observations made during the course of the testing. Tray 1 (3H:1V bank slope with live staking, live siltation willows, and riprap toe within the testing tray) Read the entire page →
From page 84... ... 84 Evaluation and Assessment of Environmentally Sensitive Stream Bank Protection Measures Test No. Discharge, ft3/s Average Shear Stress, lb/ft2 Average Erosion Depth, ft Tray 1 1 50 0.75 0.01 2 100 1.50 0.06 3 150 1.70 0.10 Tray 2 4 50 1.61 0.03 5 100 2.43 0.13 6 150 3.24 0.24 Table 3.5. Read the entire page →
From page 85... ... Testing and Appraisal of Testing Results 85 E = 0.144τ 0.0 0.5 1.0 1.5 2.0 2.5 0.0 1.0 2.0 3.0 4.0 5.0 6.0 M ax im um S tr ea m T ub e Er os io n Ra te E , i n/ hr Maximum Stream Tube Shear Stress τ, lb/ft2 50 cfs 100 cfs 150 cfs Figure 3.25. Erosion rate vs. Read the entire page →
From page 86... ... 86 Evaluation and Assessment of Environmentally Sensitive Stream Bank Protection Measures Likewise, the maximum erosion rate in any stream tube in Tray 1 was 1.0 in. per hour, while in Tray 2 the maximum erosion rate was 2.0 in. Read the entire page →
From page 87... ... Testing and Appraisal of Testing Results 87 a. Prior to testing (photo taken in greenhouse) Read the entire page →
From page 88... ... 88 Evaluation and Assessment of Environmentally Sensitive Stream Bank Protection Measures 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 0.0 2.0 4.0 6.0 8.0 10.0 12.0 De pt h, Velocity at 60% depth, /s Tray 1, 50 cfs laid over Tray 2, 50 cfs laid over Tray 1, 100 cfs laid over Tray 2, 100 cfs laid over Tray 1, 150 cfs laid over Tray 2, 150 cfs laid over Tray 1, 50 cfs standing up Tray 2, 50 cfs standing up Tray 1, 100 cfs standing up Tray 2, 100 cfs standing up Unit discharge = 5.3 cfs/ Willows laid over Willows standing up Figure 3.28. Depth vs. Read the entire page →
From page 89... ... Testing and Appraisal of Testing Results 89 3. The live siltation willows at the toe of the bank slope in Tray 1 were significantly more effective at shifting the region of high-velocity flow away from the stream bank and toward the main channel compared to the stair-step configuration of soil lifts and vegetation of the VMSE treatment in Tray 2. Read the entire page →

From page 57...

... 57 3.1 Overview and Selection of Treatments for Testing 3.1.1 Overview As noted in Section 2.6.1, a wealth of literature and documentation is available regarding environmentally sensitive stream bank protection measures. However, most of the information regarding biotechnical measures is composed of case studies of particular sites that have, in many cases, limited general applicability.