Highland Park Dam Mitigation Project Appendix C - Partners for ...

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3. Several pages of code were missing from the HEC-2 model hardcopy so assumptions were made to recreate this section. Missing from the hardcopy were cross-sections S, T, and U (as denoted in the FIS Swan Creek profile) which were within the Highland Park study area. A copy of the original code and the recreated code are included in Attachment A. Due to these missing cross-sections, the water surface elevation (WSE) for the cross-section upstream of the missing code was 0.32 feet higher than the original model for the 10-year flood event. This makes it difficult to use the recreated model as the basis for floodplain change comparison. 4. Because of the missing code in the original model, we used existing cross-section data to create the base model to which we compared proposed changes to the floodplain. Eighteen new cross-sections through the project area were incorporated into the original model to create the base model. The new cross-sections were measured in the field in November 2007. A printout of the existing conditions base code is attached (Attachment B). Existing Conditions Low Flow Analysis 5. A “low flow” event was simulated to match the water levels observed in the field. The low flow was confirmed to match the observed flow over the dam. To calibrate the model to observed water levels, only the Highland Park portion of the model was executed. Evaluation of Proposed Cross-Sections 6. The proposed cross-sections, representing the rock dams and channel upstream of the dam, were incorporated into the model. A printout of the code with proposed cross-sections is attached (Attachment C). 7. With the proposed cross-sections, the low flow event was simulated to predict the water level over the Highland Park Dam and the rock dams. 8. Shear forces and velocities of the flood events were analyzed using the HEC-2 model so that appropriate rock size could be determined for construction of the rock dams. 9. With the proposed cross-sections, the 100-year flood event was simulated resulting in no change to the flood plain as compared to the base model results (existing conditions). Results Model Recreation As discussed previously, by unfortunate coincidence, the cross-sections for the project area were missing from the hard-copy printout of the original HEC-2 model, which includes the Highland Park Pedestrian Bridge and the South Bridge. Therefore, the existing conditions model was used as the base model. For reference, a comparison of the model results are included in Table 1; Figure 1, Figure 2, and Figure 3 show graphical comparisons of the model for the 10-year, 50-year, and 100-year flood events. 10-year flood event = 5,900 cfs (from Lucas County, Ohio FIS, 2000) 50-year flood event = 8,000 cfs (from Lucas County, Ohio FIS, 2000) 100-year flood event = 9,000 cfs (from Lucas County, Ohio FIS, 2000) 2
“Original” – The results of the original HEC-2 model as printed on the hardcopy sent to us from FEMA. “Recreated” – The recreated model calibrated to the original results. “Existing” – The results of the model with the existing cross-sections through Highland Park. Table 1 Comparison of Water Surface Elevations (feet) between the Original, Recreated, and Existing Conditions Models SECTION NO. Original Recreated Existing Difference (O-R) Difference (O-E) Original Recreated RIVER MILES 10-yr 10-yr 10-yr 10 10 50-yr 50-yr 50-yr 50 50 100-yr 100-yr 100-yr 100 100 0.1 0.00 577.17 577.17 577.17 0 0 578.17 578.17 578.17 0 0 578.51 578.51 578.51 0 0 0.2 0.01 577.08 577.08 577.08 0 0 578.02 578.02 578.02 0 0 578.32 578.32 578.32 0 0 0.3 0.02 577.14 577.14 577.14 0 0 578.11 578.11 578.11 0 0 578.43 578.44 578.44 -0.01 -0.01 0.4 0.03 577.51 577.51 577.51 0 0 578.7 578.71 578.71 -0.01 -0.01 579.16 579.17 579.17 -0.01 -0.01 0.5 0.11 577.78 577.78 577.78 0 0 579.07 579.07 579.07 0 0 579.57 579.58 579.58 -0.01 -0.01 0.6 0.12 577.75 577.75 577.75 0 0 579.01 579.02 579.02 -0.01 -0.01 579.5 579.51 579.51 -0.01 -0.01 0.7 0.13 577.78 577.79 577.79 -0.01 -0.01 579.06 579.07 579.07 -0.01 -0.01 579.56 579.56 579.56 0 0 0.8 0.13 577.82 577.82 577.82 0 0 579.15 579.15 579.15 0 0 579.67 579.68 579.68 -0.01 -0.01 2 0.28 578.38 578.38 578.38 0 0 579.89 579.89 579.89 0 0 580.51 580.51 580.51 0 0 2.1 0.39 578.78 578.78 578.78 0 0 580.41 580.41 580.41 0 0 581.09 581.09 581.09 0 0 2.2 0.40 578.82 578.83 578.83 -0.01 -0.01 580.46 580.47 580.47 -0.01 -0.01 581.15 581.15 581.15 0 0 2.3 0.42 578.88 578.89 578.89 -0.01 -0.01 580.54 580.55 580.55 -0.01 -0.01 581.23 581.24 581.24 -0.01 -0.01 3 0.44 578.79 578.8 578.8 -0.01 -0.01 580.43 580.45 580.45 -0.02 -0.02 581.12 581.14 581.14 -0.02 -0.02 3.05 0.46 579.01 579.02 579.02 -0.01 -0.01 580.7 580.71 580.71 -0.01 -0.01 581.41 581.42 581.42 -0.01 -0.01 3.1 0.50 579.33 579.34 579.34 -0.01 -0.01 581.02 581.03 581.03 -0.01 -0.01 581.7 581.72 581.72 -0.02 -0.02 3.11 0.50 579.34 579.35 579.35 -0.01 -0.01 581.03 581.04 581.04 -0.01 -0.01 581.71 581.72 581.72 -0.01 -0.01 3.19 0.51 579.38 579.39 579.39 -0.01 -0.01 581.08 581.1 581.1 -0.02 -0.02 581.78 581.79 581.79 -0.01 -0.01 3.2 0.51 579.38 579.39 579.39 -0.01 -0.01 581.09 581.1 581.1 -0.01 -0.01 581.78 581.8 581.8 -0.02 -0.02 3.3 0.52 579.92 579.93 579.93 -0.01 -0.01 581.94 581.95 581.95 -0.01 -0.01 582.8 582.81 582.81 -0.01 -0.01 5 0.70 580.61 580.62 580.62 -0.01 -0.01 582.74 582.75 582.75 -0.01 -0.01 583.65 583.66 583.66 -0.01 -0.01 5.1 0.80 580.94 580.95 580.95 -0.01 -0.01 583.11 583.12 583.12 -0.01 -0.01 584.04 584.05 584.05 -0.01 -0.01 5.15 0.88 581.29 581.29 581.29 0 0 583.49 583.5 583.5 -0.01 -0.01 584.42 584.43 584.43 -0.01 -0.01 5.2 0.89 581.62 581.62 581.62 0 0 583.9 583.9 583.9 0 0 584.87 584.87 584.87 0 0 5.3 0.90 581.64 581.64 581.64 0 0 583.92 583.93 583.93 -0.01 -0.01 584.89 584.9 584.9 -0.01 -0.01 7 0.94 581.63 581.62 581.62 0.01 0.01 583.9 583.88 583.88 0.02 0.02 584.87 584.85 584.85 0.02 0.02 7.1 1.05 582.03 582.02 582.02 0.01 0.01 584.33 584.31 584.31 0.02 0.02 585.31 585.29 585.29 0.02 0.02 7.8 1.06 582.03 582.01 582.01 0.02 0.02 584.32 584.3 584.3 0.02 0.02 585.29 585.28 585.28 0.01 0.01 7.81 1.06 582.03 582.02 582.02 0.01 0.01 584.33 584.32 584.32 0.01 0.01 585.31 585.29 585.29 0.02 0.02 7.89 1.07 582.05 582.04 582.04 0.01 0.01 584.36 584.34 584.34 0.02 0.02 585.33 585.32 585.32 0.01 0.01 7.9 1.07 582.1 582.08 582.08 0.02 0.02 584.41 584.39 584.39 0.02 0.02 585.39 585.38 585.38 0.01 0.01 7.12 1.08 582.53 582.52 582.52 0.01 0.01 584.95 584.93 584.93 0.02 0.02 585.98 585.95 585.95 0.03 0.03 Existing Difference (O-R) Difference (O-E) Original Recreated Existing Difference (O-R) Difference (O-E) 3
Page 1: TETRA TECH, INC. TECHNICAL MEMORAND
Page 5 and 6: “Original” - The results of the
Page 7 and 8: Figure 3 100-year Flood Event Compa
Page 9 and 10: * Note: Q = CbH 3/ 2 ft 0.5 C = 3.3
Page 11 and 12: Figure 6 Rock Dam 1 Cross-Section C
Page 13 and 14: 30 cfs SECTIO N NO. CROSS-SECTION R
Page 15 and 16: Velocity (ft/sec) Cross-Section (No
Page 17 and 18: BASE SECTION NO. BASE RIVER MILES P
Page 19: ATTACHMENT A 1. Recreated HEC-2 Cod
Page 22 and 23: ORIGINAL * SHEET 2 BT 20 0 594 594
Page 24 and 25: ORIGINAL BT 270 599.6 592.4 270 599
Page 26 and 27: ORIGINAL GR 596 900 600 910 604 910
Page 28 and 29: ORIGINAL GR 588.7 680 588.4 700 590
Page 30 and 31: ORIGINAL GR 604 602 10 596 20 592 3
Page 32 and 33: ORIGINAL BT 736 604.8 596.2 740 604
Page 34 and 35: ORIGINAL NC 0.07 0.055 0.04 0.1 0.3
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ATTACHMENT B HEC-2 Code with Existi
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Existing Cross-Sections Model GR 58
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Existing Cross-Sections Model X3 10
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Existing Cross-Sections Model SB 1.
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Existing Cross-Sections Model J1 -1
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Proposed Cross-Sections Model T1 Ty
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Proposed Cross-Sections Model GR 56
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Proposed Cross-Sections Model X1 19
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Proposed Cross-Sections Model GR575
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Proposed Cross-Sections Model BT 52
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Proposed Cross-Sections Model NC 0.
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