Report3_Bridge Hydraulics.pdf

FHWA I-95 DAR Ramps EA Citizen Information Meeting

June 2008

I - 9 5 R A M P F R O M

F O R T B E L V O I R N O R T H A R E A ( F B N A ) F o r t B e l v o i r , V i r g i n i a

C o n s t r u c t i o n o f A c c e s s t o t h e F B N A ( F o r m e r l y k n o w n a s E n g i n e e r i n g P r o v i n g G r o u n d s )

Project AAD-VA 95 (1)

BRIDGE HYDRAULICS REPORT

Field Lark Branch Crossing Final PS&E 100% Submission

AUGUST 2011

I-95 RAMP FROM

FORT BELVOIR NORTH AREA (FBNA)

Fort Belvoir, Virginia

Construction of Access to the FBNA

(Formerly known as Engineering Proving Grounds)

BRIDGE HYDRAULICS REPORT

Field Lark Branch Crossing Final PS&E 100% Submission

U.S. Department of Transportation Federal Highway Administration

Eastern Federal Lands Highway Division

Robert G. Reed, PE

Design Director / Project Manager

Date of Approval

COOPERATING AGENCIES

U.S. Army Garrison Fort Belvoir Virginia Department of Transportation

72968 New Stamp

BRIDGE HYDRAULICS

NARRATIVE

i

CONTENTS

1. INTRODUCTION 1

2. DESIGN CRITERIA 1

3. HYDROLOGIC ANALYSIS 1

4. HYDRAULIC ANALYSIS 1

5. CHANNEL DESCRIPTION 11

6. HYDRAULIC RESULTS 11

7. SCOUR 11

APPENDIX A1 – HYDROLOGICAL CALCULATIONS

APPENDIX A2 – SOILS INFORMATION

APPENDIX B – HEC-RAS CHANNEL CROSS SECTIONS

APPENDIX C – HEC-RAS ANALYSIS RESULTS

LIST OF FIGURES

Figure 1. Project Location 2 Figure 2. FEMA Map 3 Figure 3. Drainage Map 4 Figure 4. Land Use Map 6 Figure 5. Cross Section Locations 8 Figure 6. Aerial Photo 9 Figure 7. Bridge Plan and Elevation 10

LIST OF TABLES

Table 1. Water Surface Elevations 11

LIST OF PHOTOS

Photo 1. Field Lark Branch Looking Upstream of the Proposed Bridge 12 Photo 2. Field Lark Branch West Side Bank at the Location of the

Proposed Bridge 12 Photo 3. Field Lark Branch West Overbank at the Location of the

Proposed Bridge 13 Photo 4. Field Lark Branch Looking Downstream of the Proposed Bridge 13

1. INTRODUCTION

The purpose of this report is to present the results of the hydraulic analysis of the proposed Interstate-95 ramp bridge crossing of Field Lark Branch at the FBNA, formerly known as Engineering Proving Grounds (EPG), in Fairfax County, Virginia (Figure 1). This evaluation includes the calculation of existing and proposed water surface elevations during the 2, 5, 10, 25, 50, 100, and 500-year storm events. In addition, the Ordinary High Water (OHW) elevation was determined. The HEC-RAS, Version 4.0, step-backwater computer model was used in the hydraulic analysis. The proposed bridge does not cause scour at the channel bed and provides the required freeboard according to Federal Highway Administration (FHWA) design criteria.

2. DESIGN CRITERIA

According to FHWA bridge crossings over streams are designed to convey the 50-year flood with appropriate freeboard. Freeboard is defined as the vertical clearance between the design-flood water surface and the low chord of the bridge. All bridges need to be designed with a minimum of 2 ft of freeboard. In this case, since the potential for woody debris is significant, the required freeboard is 3.5 ft to 5.0 ft according to the design criteria.

3. HYDROLOGIC ANALYSIS

The Field Lark Branch is a tributary to Accotink Creek and it is not covered by a FEMA, or other officially delineated floodplain (Figure 2). Furthermore, there is no stream gage at the site, or nearby;

consequently, the TR-55 (NRCS) methodology was used to determine design peak discharges according to FHWA procedures.

The drainage area is approximately 210 acres consisting of mostly commercial, residential and open space areas. A drainage area map is shown in Figure 3. Peak discharges were determined for the OHW, 2, 5, 10, 25, 50, 100, and 500 year storm events as 0.4, 242, 342, 432, 573, 700, 844 and 1434 cfs respectively. The 500-year peak discharge was determined as 1.7 times the 100-year discharge since no 24-hr 500-year rainfall depths are available (according to HEC-18, third edition). The OHW discharge was determined by multiplying the drainage area (in square miles) times 1.1. The OHW data was available through the VDOT Drainage Manual chapter 12.4.3. The hydrologic calculations are included in Appendix A.

4. HYDRAULIC ANALYSIS

The creek cross sections used in HEC-RAS were obtained from a recent survey and 5-ft contours provided by Fairfax County. The cross section locations are shown in Figure 5. Manning’s n values were determined by field visits and information obtained from the USGS publication “Roughness Characteristics of Natural Channels”. An aerial photo in the vicinity of the project is shown in Figure 6.

The length between the bridge MSE walls is 112’-10”. The bridge plan and elevation is shown in Figure 7.

The OHW elevation was determined to be 162.38 ft. The hydraulic results indicated that all storm events remain within the banks of the stream at the location of the proposed bridge. Table 1 shows the existing and proposed surface water elevations at each section for the 50, 100 and 500-year storm events. The freeboard provided between the 50-year flood elevation and the lowest low-member elevation of the bridge is 36.62 ft.

Figure 1. Project Location

Figure 2. FEMA Map

Figure 3. Drainage Map

Figure 3. Drainage Map (Continued)

Figure 4. Land Use Map

Figure 4. Land Use Map (Continued)

Figure 5. Cross Section Locations

Figure 6. Aerial Photo

Figure 7. Bridge Plan and Elevation

Table 1. Water Surface Elevations

Section

Existing 50-Year

(ft)

Proposed 50-Year

(ft)

Difference

(ft)

Existing 100-Year

(ft)

Proposed 100-Year

(ft) Difference

(ft)

Existing 500-Year

(ft)

Proposed 500-Year

(ft) Difference

(ft)

1230 178.59 178.59 0 178.98 178.98 0 180.18 180.18 0

1110 176.28 176.28 0 176.57 176.56 -0.01 177.57 177.56 -0.01

960 172.55 172.55 0 173.10 173.12 0.03 175.07 175.14 0.07

810 170.96 171.06 0.10 171.73 171.85 0.12 174.04 174.18 0.14

735 170.16 170.31 0.15 170.89 171.07 0.18 173.20 173.42 0.22

650 168.52 169.01 0.49 169.14 169.66 0.52 171.18 171.83 0.65

615 Bridge Bridge Bridge

580 168.14 168.15 0.01 168.73 168.75 0.02 170.74 170.80 0.06

530 167.70 167.70 0 168.22 168.22 0 169.92 169.92 0

480 167.30 167.30 0 167.73 167.73 0 169.00 169.00 0

430 166.99 166.99 0 167.39 167.39 0 168.68 168.68 0

280 165.55 165.55 0 165.87 165.87 0 166.92 166.92 0

130 161.75 161.75 0 162.08 162.08 0 163.08 163.08 0

0 158.84 158.84 0 159.12 159.12 0 160.02 160.02 0

5. CHANNEL DESCRIPTION

The channel banks are steep (1H:1V slopes or steeper, in general), vegetated, and covered with scattered rocks. The water has a brown color. The channel width is approximately 30 ft at the location of the proposed bridge. The overbanks are also steep (1H:2.5V slopes, in general) and vegetated. The stream follows a rather straight direction north of and at the location of the proposed bridge, and meanders to the south. There is a lot of debris and rocks in the stream (see Photo 1 thru Photo 4).

6. HYDRAULIC RESULTS

The 50, 100, and 500-year existing and proposed water surface elevations are shown in Table 1. These elevations are also shown on the stream sections in Appendix B. The calculated rise is due to the fact that HEC-RAS interpolates internal sections for the bridge, one upstream (BU) and one downstream (BD). These cross sections are identical to sections 650 and 580 respectively (Figure), therefore the channel between the interpolated sections and the actual sections becomes flat, where in reality it is not. The slope will also be steeper between BU and BD. These slight changes in the geometry cause the rise of the surface water elevation. The results of the HEC-RAS analysis are included in Appendix C.

7. SCOUR

Since the proposed bridge does not cause contraction of the channel and there are no piers within the stream, no contraction or local scour occurs. Another form of potential scour would be due to the natural stream migration and meandering over a long period of time. This type of scour cannot be easily modeled or evaluated. In lieu of modeling the scour due to natural migration, the foundations for the bridge were designed to resist the potential scour. The west foundation consists of lean concrete resting on rock; the top of this lean concrete was raised to above the 100-year storm elevation. The east foundation includes a reinforced concrete pad to above the 100-year storm which is encircled by sheet pile driven to rock which shall remain in place.

Photo 1. Field Lark Branch Looking Upstream of the Proposed Bridge

Photo 2. Field Lark Branch West Side Bank at the Location of the Proposed Bridge

Photo 3. Field Lark Branch West Overbank at the Location of the Proposed Bridge

Photo 4. Field Lark Branch Looking Downstream of the Proposed Bridge

A-1

APPENDIX A1 – HYDROLOGICAL CALCULATIONS

NRCS PEAK FLOW METHOD (formerly SCS, for 200 acres and above)

Weighted Curve Number

HYDROLOGIC GROUP LAND USE CN ACRES ACRES*CN

B OPEN SPACE 61 34.28 2091.08

C OPEN SPACE 74 26.06 1928.44

D COMMERCIAL 95 25.65 2436.75

D COMMERCIAL 95 13.18 1252.10

D RESIDENTIAL-2 85 74.60 6341.00

D PAVED W/ DITCH 93 36.03 3350.79

209.80 17400.16

TOTAL DA (Acres)= 209.80

WEIGHTED CN= 82.94

TIME OF CONCENTRATION

SHEET FLOW (TC1)

TR-55 EQ. 3-3

TC1=(0.007(nL)^0.8)/(P2)^0.5 * s^0.40 L (ft) = 162 s (ft/ft) = 0.028 n (Woods, light) = 0.4

TC1(hours) = 0.47

CHANNEL FLOW (TC2)

TR-55 EQ. 3-4

V=1.49r^0.67 * s^0.5 / n

TC2= L/(3600V)

V (ft/s) = 2.43 r (ft) = 0.90 L (ft) = 319.00 s (ft/ft) = 0.02 n = 0.07

TC2 (hours) = 0.04

PIPE FLOW (TC3)

TC3 = L/(V*3600)

L (ft) = 3404 V (fps) = 10

TC3 (hours) = 0.09

CHANNEL FLOW (TC4)

TR-55 EQ. 3-4

V=1.49r^0.67 * s^0.5 / n

TC4= L/(3600V)

V (ft/s) = 2.67 r (ft) = 0.87 L (ft) = 3229.20 s (ft/ft) = 0.02 n = 0.07

TC4 (hours) = 0.34

TC= TC1+TC2+TC3+TC4

TC (hours) = 0.93

PEAK DISCHARGE

Qp (cfs)=Qu * Ak * Qd HEC-22 Eq. 3-17

Qp (cfs) = Peak flow Qu (ft^3 / s / mi^2 / in) = Unit peak flow

Ak (mi^2) = Basin area Qd (in) = Runoff depth

Qu = Ku * 10^(Co+C1*LOG(TC) + C2*(LOG(TC))^2) HEC-22 Eq. 3-18

Ku = 1 For English units LOG (TC) = -0.03 Table 3-7 in HEC-22 for Type II Rainfall

Co = 2.55323 C1 = -0.61512 C2 = -0.16403

Qu (ft^3/s/mi^2/in) = 372.59 Ak (mi^2) = 0.328

Qd (in) = [(P-Ia)^2]/(P+0.8S) HEC-22 Eq. 3-15

S = 1000/CN - 10 = 1.27

Ia = 0.2 S = 0.25

Ia/P = 0.10

Qd (in) = Runoff depth P (in) = Depth of 24 hr precipitation Ia (in) = Initial abstraction Ia (in) = 0.2 S S (in) = Potential maximum retention after runoff begins

P2 (in) = 3.11 Appendix 11C-3 VDOT Drainage Manual P5 (in) = 4.00

P10 (in) = 4.78 P25 (in) = 5.98 P50 (in) = 7.05

P100 (in) = 8.25

Qd = 1.98 2 YEAR

2.80 5 YEAR

3.54 10 YEAR

4.69 25 YEAR

5.73 50 YEAR

6.90 100 YEAR

Qp (OHW) = (DA / 640) x 1.1 0.4 cfs (OHW) Qp (2 year) = 242 cfs Qp (5 year) = 342 cfs

Qp (10 year) = 432 cfs Qp (25 year) = 573 cfs Qp (50 year) = 700 cfs

Qp (100 year) = 844 cfs

Qp (500 year)= Qp(100 year) * 1.7

Qp (500 year) = 1434 cfs

Intensity, I (in/hr)

Flow, Q (cfs)

Intensity, I (in/hr)

Flow, Q (cfs)

Intensity, I (in/hr)

Flow, Q (cfs)

Intensity, I (in/hr)

Flow, Q (cfs)

Intensity, I (in/hr)

Flow, Q (cfs)

Intensity, I (in/hr)

Flow, Q (cfs)

DAR Natural, suburban 9,138,888 209.8 0.33 1.45 0.048 7,114 1.35 250 162 1.24 0.6 1.05 62.84 1.47653 242 1.811529 297 2.094927 343 2.473916 405 2.848361 467 3.175033 520

FACTORS 2-YEAR 5-YEAR 10-YEAR 25-YEAR 50-YEAR 100-YEAR

B 55.09 54.2 47.7 39.18 36.24 32.29 D 11.5 11 9.5 7.25 6.5 5 E 0.84 0.79 0.73 0.65 0.6 0.55

10 Year InfoElev. at U/S

End of L (Ft)

Elev. at D/S

End of L (Ft)

2 Year Info 5 Year InfoTime of Concentra tion, Tc (Min)

Time of Concentra tion, Tc (hours)

Channel Length, L

(Miles) Slope, S

RAINFALL INTENSITY FACTORS

Equiv Channel

Length, L' (miles)

Manning's Roughness

Coefficient, n

Channel Length, L

(Ft)

SNYDER METHOD

Basin ID Type of

Watershed Area (SF) Area

(Acres) Area (Sq

Mile)

100 Year Info25 Year InfoTime of Conc

Adjustment Factor, Ct

50 Year Info

A-2

APPENDIX A2 – SOILS INFORMATION

Fie ld L ark Bran ch

Lon g B ran ch

Cree k

Ba ck lick R d

Lo isd ale R d

La yto n D r

Cisnna Rd

Barta Rd

Hooes Rd

La ma r D r

Lois Dr

Os tm ey er

Lo op

Ru sk in St

Heller Loop

Gormel Dr

Co ns tan tin e A ve

Hampton Manor Pl

Lavender Ln

Je rom e S t

Belinger Ct

Be ve rly P ark D r Beverly Ln

Darby Ln

Springfield Center DrVilla del Rey Ln

Constance Dr

Be thn al Ct

Rid ge wa y D r

Sumpter Ln

Dyer Ct Itte Ln

Tule St Joh n Rylands Way

Conway Ct Ba ck lick

R d

72B

7B

91C

E

A

7B

7B

D

W

309400

309400

309600

309600

309800

309800

310000

310000

310200

310200

310400

310400

310600

310600

0 700 1,400 2,100350 Feet

0 100 200 30050 Meters

38° 46' 0''

° 1

0'

38° 44' 55''

° 1

0'

38° 44' 54''

38° 45' 59''

° 1 1'

° 1

1'

Map Scale: 1:9,500 if printed on A size (8.5" x 11") sheet.

Hydrologic Soil Group—Fairfax County, Virginia

Natural ResourcesNatural ResourcesNatural ResourcesNatural Resources Conservation ServiceConservation ServiceConservation ServiceConservation Service

Web Soil Survey National Cooperative Soil Survey

4/12/2011

MAP LEGEND MAP INFORMATION

Area of Interest (AOI) Area of Interest (AOI)

Soils Soil Map Units

Soil Ratings A

A/D

B

B/D

C

C/D

D

Not rated or not available

Political Features Cities

Water Features Oceans

Streams and Canals

Transportation Rails

Interstate Highways

US Routes

Major Roads

Local Roads

Map Scale: 1:9,500 if printed on A size (8.5" × 11") sheet.

The soil surveys that comprise your AOI were mapped at 1:12,000.

Please rely on the bar scale on each map sheet for accurate map measurements.

Source of Map: Natural Resources Conservation Service Web Soil Survey URL: http://websoilsurvey.nrcs.usda.gov Coordinate System: UTM Zone 18N NAD83

This product is generated from the USDA-NRCS certified data as of the version date(s) listed below.

Soil Survey Area: Fairfax County, Virginia Survey Area Data: Version 10, Aug 19, 2010

Date(s) aerial images were photographed: 6/24/2003

The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident.

Hydrologic Soil Group–Fairfax County, Virginia

Natural Resources Conservation Service

Web Soil Survey National Cooperative Soil Survey

Hydrologic Soil Group

Hydrologic Soil Group— Summary by Map Unit — Fairfax County, Virginia

Map unit symbol Map unit name Rating Acres in AOI Percent of AOI

7B Beltsville silt loam, 2 to 7 percent slopes C 18.6 8.8%

30A Codorus and Hatboro soils, 0 to 2 percent slopes, occasionally flooded

C 6.8 3.2%

66 Kingstowne sandy clay loam, 0 to 45 percent slopes

D 31.4 14.9%

72B Kingstowne-Sassafras-Neabsco complex, 2 to 7 percent slopes

D 66.3 31.5%

91C Sassafras-Marumsco complex, 7 to 15 percent slopes

B 10.9 5.2%

91D Sassafras-Marumsco complex, 15 to 25 percent slopes

B 4.9 2.3%

91E Sassafras-Marumsco complex, 25 to 45 percent slopes

B 9.3 4.4%

95 Urban land 60.9 28.9%

W Water 1.7 0.8%

Totals for Area of Interest 210.8 100.0%

Hydrologic Soil Group–Fairfax County, Virginia

Natural Resources Conservation Service

Web Soil Survey National Cooperative Soil Survey

Description

Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms.

The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows:

Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission.

Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission.

Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission.

Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material.

These soils have a very slow rate of water transmission.

If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes.

Rating Options

Aggregation Method: Dominant Condition

Component Percent Cutoff: None Specified

Tie-break Rule: Lower

Hydrologic Soil Group–Fairfax County, Virginia

Natural Resources Conservation Service

Web Soil Survey National Cooperative Soil Survey

B-1

APPENDIX B – HEC-RAS CHANNEL CROSS SECTIONS

-150 -100 -50 0 50 100 150

Field Lark Branch Plan: 1) Existing 4/27/2011 2) Proposed 4/27/2011

River = Field Lark Branc Reach = Reach 1 RS = 1230 Upstream Section

Station (ft)

E le v a ti o n ft

Legend

WS 500-Year - Existing

WS 500-Year - Proposed

WS 100-Year - Proposed

WS 100-Year - Existing

WS 50-Year - Existing

WS 50-Year - Proposed

Ground

Levee

Bank Sta

.15 .07 .15

Field Lark Branch Plan: 1) Existing 4/27/2011 2) Proposed 4/27/2011

River = Field Lark Branc Reach = Reach 1 RS = 1110

Station (ft)

E le v a ti o n ft

Legend

WS 500-Year - Existing

WS 500-Year - Proposed

WS 100-Year - Proposed

WS 100-Year - Existing

WS 50-Year - Existing

WS 50-Year - Proposed

Ground

Field Lark Branch Plan: 1) Existing 4/27/2011 2) Proposed 4/27/2011

River = Field Lark Branc Reach = Reach 1 RS = 960

Station (ft)

E le v a ti o n ft

Legend

WS 500-Year - Existing

WS 500-Year - Proposed

WS 100-Year - Proposed

WS 100-Year - Existing

WS 50-Year - Existing

WS 50-Year - Proposed

Ground

Bank Sta

Field Lark Branch Plan: 1) Existing 4/27/2011 2) Proposed 4/27/2011

River = Field Lark Branc Reach = Reach 1 RS = 810

Station (ft)

E le v a ti o n ft

Legend

WS 500-Year - Existing

WS 500-Year - Proposed

WS 100-Year - Proposed

WS 100-Year - Existing

WS 50-Year - Existing

WS 50-Year - Proposed

Ground

Field Lark Branch Plan: 1) Existing 4/27/2011 2) Proposed 4/27/2011

River = Field Lark Branc Reach = Reach 1 RS = 735

Station (ft)

E le v a ti o n ft

Legend

WS 500-Year - Existing

WS 500-Year - Proposed

WS 100-Year - Proposed

WS 100-Year - Existing

WS 50-Year - Existing

WS 50-Year - Proposed

Ground

-200 -100 0 100 200 300

Field Lark Branch Plan: 1) Existing 4/27/2011 2) Proposed 4/27/2011

River = Field Lark Branc Reach = Reach 1 RS = 650 Section Upstream of Bridge

Station (ft)

E le v a ti o n ft

Legend

WS 500-Year - Existing

WS 500-Year - Proposed

WS 100-Year - Proposed

WS 100-Year - Existing

WS 50-Year - Existing

WS 50-Year - Proposed

Ground

Bank Sta

-200 -100 0 100 200 300

Field Lark Branch Plan: 1) Existing 4/27/2011 2) Proposed 4/27/2011

River = Field Lark Branc Reach = Reach 1 RS = 615 BR

Station (ft)

E le v a ti o n ft

Legend

WS 500-Year - Existing

WS 500-Year - Proposed

WS 100-Year - Proposed

WS 100-Year - Existing

WS 50-Year - Existing

WS 50-Year - Proposed

Ground

-300 -200 -100 0 100 200

Field Lark Branch Plan: 1) Existing 4/27/2011 2) Proposed 4/27/2011

River = Field Lark Branc Reach = Reach 1 RS = 615 BR

Station (ft)

E le v a ti o n ft

Legend

WS 500-Year - Existing

WS 500-Year - Proposed

WS 100-Year - Proposed

WS 100-Year - Existing

WS 50-Year - Existing

WS 50-Year - Proposed

Ground

Field Lark Branch Plan: 1) Existing 4/27/2011 2) Proposed 4/27/2011

River = Field Lark Branc Reach = Reach 1 RS = 580 Section Downstream of Bridge

Station (ft)

E le v a ti o n ft

Legend

WS 500-Year - Existing

WS 500-Year - Proposed

WS 100-Year - Proposed

WS 100-Year - Existing

WS 50-Year - Existing

WS 50-Year - Proposed

Ground

Bank Sta

Field Lark Branch Plan: 1) Existing 4/27/2011 2) Proposed 4/27/2011

River = Field Lark Branc Reach = Reach 1 RS = 530

Station (ft)

E le v a ti o n ft

Legend

WS 500-Year - Existing

WS 500-Year - Proposed

WS 100-Year - Proposed

WS 100-Year - Existing

WS 50-Year - Existing

WS 50-Year - Proposed

Ground

Field Lark Branch Plan: 1) Existing 4/27/2011 2) Proposed 4/27/2011

River = Field Lark Branc Reach = Reach 1 RS = 480

Station (ft)

E le v a ti o n ft

Legend

WS 500-Year - Existing

WS 500-Year - Proposed

WS 100-Year - Proposed

WS 100-Year - Existing

WS 50-Year - Existing

WS 50-Year - Proposed

Ground

Field Lark Branch Plan: 1) Existing 4/27/2011 2) Proposed 4/27/2011

River = Field Lark Branc Reach = Reach 1 RS = 430

Station (ft)

E le v a ti o n ft

Legend

WS 500-Year - Existing

WS 500-Year - Proposed

WS 100-Year - Proposed

WS 100-Year - Existing

WS 50-Year - Existing

WS 50-Year - Proposed

Ground

Bank Sta

-200 -100 0 100 200

Field Lark Branch Plan: 1) Existing 4/27/2011 2) Proposed 4/27/2011

River = Field Lark Branc Reach = Reach 1 RS = 280

Station (ft)

E le v a ti o n ft

Legend

WS 500-Year - Existing

WS 500-Year - Proposed

WS 100-Year - Proposed

WS 100-Year - Existing

WS 50-Year - Existing

WS 50-Year - Proposed

Ground

-200 -100 0 100 200

Field Lark Branch Plan: 1) Existing 4/27/2011 2) Proposed 4/27/2011

River = Field Lark Branc Reach = Reach 1 RS = 130

Station (ft)

E le v a ti o n ft

Legend

WS 500-Year - Existing

WS 500-Year - Proposed

WS 100-Year - Proposed

WS 100-Year - Existing

WS 50-Year - Existing

WS 50-Year - Proposed

Ground

-300 -200 -100 0 100 200 300

Field Lark Branch Plan: 1) Existing 4/27/2011 2) Proposed 4/27/2011

River = Field Lark Branc Reach = Reach 1 RS = 0 Downstream section

Station (ft)

E le v a ti o n ft

Legend

WS 500-Year - Existing

WS 500-Year - Proposed

WS 100-Year - Proposed

WS 100-Year - Existing

WS 50-Year - Existing

WS 50-Year - Proposed

Ground

Bank Sta

C-1

APPENDIX C – HEC-RAS ANALYSIS RESULTS

HEC-RAS River: Field Lark Branc Reach: Reach 1

Reach River Sta Profile Plan Q Total Min Ch El W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl Flow Area Top Width Froude # Chl

(cfs) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)

Reach 1 1230 OHW Existing 0.40 175.00 175.03 175.03 175.04 0.211002 0.85 0.47 18.11 0.93

Reach 1 1230 OHW Proposed 0.40 175.00 175.03 175.03 175.04 0.211002 0.85 0.47 18.11 0.93

Reach 1 1230 2-Year Existing 242.00 175.00 176.99 176.65 177.45 0.034550 5.43 44.59 26.76 0.74

Reach 1 1230 2-Year Proposed 242.00 175.00 176.99 176.65 177.45 0.034550 5.43 44.59 26.76 0.74

Reach 1 1230 5-Year Existing 342.00 175.00 177.43 177.05 177.99 0.034191 6.03 56.68 28.68 0.76

Reach 1 1230 5-Year Proposed 342.00 175.00 177.43 177.05 177.99 0.034191 6.03 56.68 28.68 0.76

Reach 1 1230 10-Year Existing 432.00 175.00 177.75 177.36 178.41 0.034845 6.53 66.19 30.11 0.78

Reach 1 1230 10-Year Proposed 432.00 175.00 177.75 177.36 178.41 0.034845 6.53 66.19 30.11 0.78

Reach 1 1230 25-Year Existing 573.00 175.00 178.21 177.80 179.00 0.035055 7.12 80.44 32.12 0.79

Reach 1 1230 25-Year Proposed 573.00 175.00 178.21 177.80 179.00 0.035055 7.12 80.44 32.12 0.79

Reach 1 1230 50-Year Existing 700.00 175.00 178.59 178.15 179.47 0.034676 7.53 92.96 33.79 0.80

Reach 1 1230 50-Year Proposed 700.00 175.00 178.59 178.15 179.47 0.034676 7.53 92.96 33.79 0.80

Reach 1 1230 100-Year Existing 844.00 175.00 178.98 178.52 179.96 0.034357 7.93 106.49 35.51 0.81

Reach 1 1230 100-Year Proposed 844.00 175.00 178.98 178.52 179.96 0.034357 7.93 106.49 35.51 0.81

Reach 1 1230 500-Year Existing 1434.00 175.00 180.18 179.76 181.56 0.035505 9.41 152.66 43.84 0.85

Reach 1 1230 500-Year Proposed 1434.00 175.00 180.18 179.76 181.56 0.035505 9.41 152.66 43.84 0.85

Reach 1 1110 OHW Existing 0.40 171.08 171.44 171.45 0.008634 0.62 0.64 3.52 0.26

Reach 1 1110 OHW Proposed 0.40 171.08 171.44 171.45 0.008634 0.62 0.64 3.52 0.26

Reach 1 1110 2-Year Existing 242.00 171.08 174.82 175.02 0.012630 3.57 67.78 36.25 0.46

Reach 1 1110 2-Year Proposed 242.00 171.08 174.82 175.02 0.012630 3.57 67.78 36.25 0.46

Reach 1 1110 5-Year Existing 342.00 171.08 175.26 175.51 0.013012 4.06 84.87 43.12 0.48

Reach 1 1110 5-Year Proposed 342.00 171.08 175.26 175.51 0.013012 4.06 84.87 43.12 0.48

Reach 1 1110 10-Year Existing 432.00 171.08 175.58 175.88 0.013152 4.47 99.71 49.53 0.49

Reach 1 1110 10-Year Proposed 432.00 171.08 175.58 175.88 0.013152 4.47 99.71 49.53 0.49

Reach 1 1110 25-Year Existing 573.00 171.08 175.98 176.38 0.013832 5.06 121.59 57.69 0.52

Reach 1 1110 25-Year Proposed 573.00 171.08 175.98 176.38 0.013832 5.06 121.59 57.69 0.52

Reach 1 1110 50-Year Existing 700.00 171.08 176.28 176.75 0.014802 5.57 139.30 63.54 0.55

Reach 1 1110 50-Year Proposed 700.00 171.08 176.28 176.75 0.014802 5.57 139.30 63.54 0.55

Reach 1 1110 100-Year Existing 844.00 171.08 176.56 177.12 0.015952 6.12 158.08 69.20 0.57

Reach 1 1110 100-Year Proposed 844.00 171.08 176.56 177.12 0.015952 6.12 158.08 69.20 0.57

Reach 1 1110 500-Year Existing 1434.00 171.08 177.56 178.43 0.018333 7.75 237.27 89.19 0.64

Reach 1 1110 500-Year Proposed 1434.00 171.08 177.56 178.43 0.018333 7.75 237.27 89.19 0.64

Reach 1 960 OHW Existing 0.40 167.78 168.00 168.00 168.06 0.154609 1.89 0.21 1.90 1.00

Reach 1 960 OHW Proposed 0.40 167.78 168.00 168.00 168.06 0.154609 1.89 0.21 1.90 1.00

Reach 1 960 2-Year Existing 242.00 167.78 170.63 170.63 171.43 0.057893 7.25 35.76 27.88 0.97

Reach 1 960 2-Year Proposed 242.00 167.78 170.63 170.63 171.43 0.057893 7.25 35.76 27.88 0.97

Reach 1 960 5-Year Existing 342.00 167.78 171.09 171.09 172.02 0.049807 7.88 50.31 34.51 0.94

Reach 1 960 5-Year Proposed 342.00 167.78 171.09 171.09 172.02 0.049807 7.88 50.31 34.51 0.94

Reach 1 960 10-Year Existing 432.00 167.78 171.46 171.46 172.47 0.045432 8.33 63.86 39.69 0.92

Reach 1 960 10-Year Proposed 432.00 167.78 171.46 171.46 172.47 0.045432 8.33 63.86 39.69 0.92

HEC-RAS River: Field Lark Branc Reach: Reach 1 (Continued)

Reach River Sta Profile Plan Q Total Min Ch El W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl Flow Area Top Width Froude # Chl

(cfs) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)

Reach 1 960 25-Year Existing 573.00 167.78 172.03 171.93 173.09 0.037696 8.68 88.76 47.78 0.86

Reach 1 960 25-Year Proposed 573.00 167.78 172.03 171.93 173.09 0.037696 8.68 88.76 47.78 0.86

Reach 1 960 50-Year Existing 700.00 167.78 172.55 172.32 173.58 0.030929 8.71 115.83 55.24 0.80

Reach 1 960 50-Year Proposed 700.00 167.78 172.55 172.32 173.58 0.030929 8.71 115.83 55.24 0.80

Reach 1 960 100-Year Existing 844.00 167.78 173.12 172.71 174.10 0.025348 8.69 149.66 63.34 0.74

Reach 1 960 100-Year Proposed 844.00 167.78 173.12 172.71 174.10 0.025348 8.69 149.66 63.34 0.74

Reach 1 960 500-Year Existing 1434.00 167.78 175.14 175.97 0.014551 8.54 306.57 91.17 0.60

Reach 1 960 500-Year Proposed 1434.00 167.78 175.14 175.97 0.014551 8.54 306.57 91.17 0.60

Reach 1 810 OHW Existing 0.40 163.25 163.70 163.70 0.000954 0.24 1.67 7.47 0.09

Reach 1 810 OHW Proposed 0.40 163.25 163.70 163.70 0.000954 0.24 1.67 7.47 0.09

Reach 1 810 2-Year Existing 242.00 163.25 167.92 168.16 0.008442 3.90 62.05 18.42 0.37

Reach 1 810 2-Year Proposed 242.00 163.25 167.92 168.16 0.008442 3.90 62.05 18.42 0.37

Reach 1 810 5-Year Existing 342.00 163.25 168.76 169.06 0.008633 4.36 80.97 32.31 0.39

Reach 1 810 5-Year Proposed 342.00 163.25 168.76 169.06 0.008633 4.36 80.97 32.31 0.39

Reach 1 810 10-Year Existing 432.00 163.25 169.42 169.75 0.008306 4.63 104.24 38.54 0.38

Reach 1 810 10-Year Proposed 432.00 163.25 169.42 169.75 0.008306 4.63 104.24 38.54 0.38

Reach 1 810 25-Year Existing 573.00 163.25 170.33 170.68 0.007701 4.89 143.31 46.73 0.38

Reach 1 810 25-Year Proposed 573.00 163.25 170.33 170.68 0.007701 4.89 143.31 46.73 0.38

Reach 1 810 50-Year Existing 700.00 163.25 171.06 171.42 0.007167 5.03 178.65 49.93 0.37

Reach 1 810 50-Year Proposed 700.00 163.25 171.06 171.42 0.007167 5.03 178.65 49.93 0.37

Reach 1 810 100-Year Existing 844.00 163.25 171.85 172.21 0.006450 5.13 219.64 55.73 0.36

Reach 1 810 100-Year Proposed 844.00 163.25 171.85 172.21 0.006450 5.13 219.64 55.73 0.36

Reach 1 810 500-Year Existing 1434.00 163.25 174.18 174.59 0.005400 5.76 376.72 77.62 0.34

Reach 1 810 500-Year Proposed 1434.00 163.25 174.18 174.59 0.005400 5.76 376.72 77.62 0.34

Reach 1 735 OHW Existing 0.40 163.34 163.41 163.41 163.45 0.268385 1.42 0.28 6.09 1.16

Reach 1 735 OHW Proposed 0.40 163.34 163.41 163.41 163.45 0.268385 1.42 0.28 6.09 1.16

Reach 1 735 2-Year Existing 242.00 163.34 167.24 167.49 0.009457 3.97 60.97 19.30 0.39

Reach 1 735 2-Year Proposed 242.00 163.34 167.24 167.49 0.009457 3.97 60.97 19.30 0.39

Reach 1 735 5-Year Existing 342.00 163.34 168.08 168.38 0.009528 4.40 77.65 20.68 0.40

Reach 1 735 5-Year Proposed 342.00 163.34 168.08 168.38 0.009528 4.40 77.65 20.68 0.40

Reach 1 735 10-Year Existing 432.00 163.34 168.73 169.07 0.009615 4.72 91.46 21.75 0.41

Reach 1 735 10-Year Proposed 432.00 163.34 168.73 169.07 0.009615 4.72 91.46 21.75 0.41

Reach 1 735 25-Year Existing 573.00 163.34 169.62 170.03 0.009791 5.14 111.42 23.21 0.41

Reach 1 735 25-Year Proposed 573.00 163.34 169.62 170.03 0.009791 5.14 111.42 23.21 0.41

Reach 1 735 50-Year Existing 700.00 163.34 170.31 170.78 0.009972 5.47 128.04 24.36 0.42

Reach 1 735 50-Year Proposed 700.00 163.34 170.31 170.78 0.009972 5.47 128.04 24.36 0.42

Reach 1 735 100-Year Existing 844.00 163.34 171.07 171.58 0.010705 5.71 147.77 28.25 0.44

Reach 1 735 100-Year Proposed 844.00 163.34 171.07 171.58 0.010705 5.71 147.77 28.25 0.44

Reach 1 735 500-Year Existing 1434.00 163.34 173.42 174.04 0.009594 6.31 232.66 44.54 0.44

Reach 1 735 500-Year Proposed 1434.00 163.34 173.42 174.04 0.009594 6.31 232.66 44.54 0.44

Reach River Sta Profile Plan Q Total Min Ch El W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl Flow Area Top Width Froude # Chl

(cfs) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)

Reach 1 650 OHW Existing 0.40 162.11 162.38 162.23 162.38 0.001974 0.32 1.26 6.29 0.13

Reach 1 650 OHW Proposed 0.40 162.11 162.38 162.23 162.38 0.001974 0.32 1.26 6.29 0.13

Reach 1 650 2-Year Existing 242.00 162.11 166.14 164.77 166.49 0.014613 4.75 50.90 16.73 0.48

Reach 1 650 2-Year Proposed 242.00 162.11 166.14 164.77 166.49 0.014613 4.75 50.90 16.73 0.48

Reach 1 650 5-Year Existing 342.00 162.11 166.93 165.34 167.36 0.014991 5.29 64.61 18.02 0.49

Reach 1 650 5-Year Proposed 342.00 162.11 166.93 165.34 167.36 0.014991 5.29 64.61 18.02 0.49

Reach 1 650 10-Year Existing 432.00 162.11 167.54 165.79 168.04 0.015273 5.68 76.00 19.03 0.50

Reach 1 650 10-Year Proposed 432.00 162.11 167.54 165.79 168.04 0.015273 5.68 76.00 19.03 0.50

Reach 1 650 25-Year Existing 573.00 162.11 168.37 166.44 168.97 0.015767 6.21 92.30 20.39 0.51

Reach 1 650 25-Year Proposed 573.00 162.11 168.37 166.44 168.97 0.015767 6.21 92.30 20.39 0.51

Reach 1 650 50-Year Existing 700.00 162.11 169.01 166.95 169.69 0.016269 6.62 105.70 21.44 0.53

Reach 1 650 50-Year Proposed 700.00 162.11 169.01 166.95 169.69 0.016269 6.62 105.70 21.44 0.53

Reach 1 650 100-Year Existing 844.00 162.11 169.66 167.48 170.43 0.016777 7.03 119.98 22.51 0.54

Reach 1 650 100-Year Proposed 844.00 162.11 169.66 167.48 170.43 0.016777 7.03 119.98 22.51 0.54

Reach 1 650 500-Year Existing 1434.00 162.11 171.83 169.28 172.90 0.018146 8.30 172.81 26.08 0.57

Reach 1 650 500-Year Proposed 1434.00 162.11 171.83 169.28 172.90 0.018146 8.30 172.81 26.08 0.57

Reach 1 615 Bridge

Reach 1 580 OHW Existing 0.40 160.64 160.79 160.79 160.82 0.183951 1.46 0.27 4.26 1.01

Reach 1 580 OHW Proposed 0.40 160.64 160.79 160.79 160.82 0.183951 1.46 0.27 4.26 1.01

Reach 1 580 2-Year Existing 242.00 160.64 165.31 165.44 0.004234 2.95 82.06 22.42 0.27

Reach 1 580 2-Year Proposed 242.00 160.64 165.31 165.44 0.004234 2.95 82.06 22.42 0.27

Reach 1 580 5-Year Existing 342.00 160.64 166.14 166.32 0.004673 3.38 101.29 23.90 0.29

Reach 1 580 5-Year Proposed 342.00 160.64 166.14 166.32 0.004673 3.38 101.29 23.90 0.29

Reach 1 580 10-Year Existing 432.00 160.64 166.76 166.97 0.005063 3.71 116.35 24.99 0.30

Reach 1 580 10-Year Proposed 432.00 160.64 166.76 166.97 0.005063 3.71 116.35 24.99 0.30

Reach 1 580 25-Year Existing 573.00 160.64 167.56 167.83 0.005676 4.19 136.91 26.41 0.32

Reach 1 580 25-Year Proposed 573.00 160.64 167.56 167.83 0.005676 4.19 136.91 26.41 0.32

Reach 1 580 50-Year Existing 700.00 160.64 168.15 168.48 0.006239 4.58 153.00 27.47 0.34

Reach 1 580 50-Year Proposed 700.00 160.64 168.15 168.48 0.006239 4.58 153.00 27.47 0.34

Reach 1 580 100-Year Existing 844.00 160.64 168.75 169.14 0.006813 4.97 169.83 28.54 0.36

Reach 1 580 100-Year Proposed 844.00 160.64 168.75 169.14 0.006813 4.97 169.83 28.54 0.36

Reach 1 580 500-Year Existing 1434.00 160.64 170.80 171.39 0.008349 6.19 231.87 32.65 0.40

Reach 1 580 500-Year Proposed 1434.00 160.64 170.80 171.39 0.008349 6.19 231.87 32.65 0.40

Reach 1 530 OHW Existing 0.40 158.94 160.12 160.12 0.000023 0.07 5.53 8.53 0.02

Reach 1 530 OHW Proposed 0.40 158.94 160.12 160.12 0.000023 0.07 5.53 8.53 0.02

Reach 1 530 2-Year Existing 242.00 158.94 165.11 165.24 0.003805 2.92 82.96 19.37 0.25

Reach 1 530 2-Year Proposed 242.00 158.94 165.11 165.24 0.003805 2.92 82.96 19.37 0.25

Reach 1 530 5-Year Existing 342.00 158.94 165.89 166.08 0.004730 3.47 98.50 20.46 0.28

Reach River Sta Profile Plan Q Total Min Ch El W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl Flow Area Top Width Froude # Chl

(cfs) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)

Reach 1 530 5-Year Proposed 342.00 158.94 165.89 166.08 0.004730 3.47 98.50 20.46 0.28

Reach 1 530 10-Year Existing 432.00 158.94 166.46 166.70 0.005525 3.91 110.37 21.25 0.30

Reach 1 530 10-Year Proposed 432.00 158.94 166.46 166.70 0.005525 3.91 110.37 21.25 0.30

Reach 1 530 25-Year Existing 573.00 158.94 167.18 167.50 0.006762 4.54 126.09 22.26 0.34

Reach 1 530 25-Year Proposed 573.00 158.94 167.18 167.50 0.006762 4.54 126.09 22.26 0.34

Reach 1 530 50-Year Existing 700.00 158.94 167.70 168.10 0.007917 5.08 137.90 22.99 0.37

Reach 1 530 50-Year Proposed 700.00 158.94 167.70 168.10 0.007917 5.08 137.90 22.99 0.37

Reach 1 530 100-Year Existing 844.00 158.94 168.22 168.71 0.009183 5.63 149.91 23.71 0.39

Reach 1 530 100-Year Proposed 844.00 158.94 168.22 168.71 0.009183 5.63 149.91 23.71 0.39

Reach 1 530 500-Year Existing 1434.00 158.94 169.92 170.76 0.015121 7.39 193.97 30.48 0.52

Reach 1 530 500-Year Proposed 1434.00 158.94 169.92 170.76 0.015121 7.39 193.97 30.48 0.52

Reach 1 480 OHW Existing 0.40 159.16 160.12 160.12 0.000006 0.04 9.26 11.38 0.01

Reach 1 480 OHW Proposed 0.40 159.16 160.12 160.12 0.000006 0.04 9.26 11.38 0.01

Reach 1 480 2-Year Existing 242.00 159.16 164.93 165.06 0.003575 2.85 84.78 20.00 0.24

Reach 1 480 2-Year Proposed 242.00 159.16 164.93 165.06 0.003575 2.85 84.78 20.00 0.24

Reach 1 480 5-Year Existing 342.00 159.16 165.66 165.84 0.004572 3.42 99.90 21.31 0.28

Reach 1 480 5-Year Proposed 342.00 159.16 165.66 165.84 0.004572 3.42 99.90 21.31 0.28

Reach 1 480 10-Year Existing 432.00 159.16 166.19 166.42 0.005435 3.88 111.38 22.25 0.31

Reach 1 480 10-Year Proposed 432.00 159.16 166.19 166.42 0.005435 3.88 111.38 22.25 0.31

Reach 1 480 25-Year Existing 573.00 159.16 166.84 167.16 0.006807 4.54 126.34 23.43 0.34

Reach 1 480 25-Year Proposed 573.00 159.16 166.84 167.16 0.006807 4.54 126.34 23.43 0.34

Reach 1 480 50-Year Existing 700.00 159.16 167.30 167.70 0.008146 5.10 137.16 24.24 0.38

Reach 1 480 50-Year Proposed 700.00 159.16 167.30 167.70 0.008146 5.10 137.16 24.24 0.38

Reach 1 480 100-Year Existing 844.00 159.16 167.73 168.24 0.009683 5.71 147.85 25.01 0.41

Reach 1 480 100-Year Proposed 844.00 159.16 167.73 168.24 0.009683 5.71 147.85 25.01 0.41

Reach 1 480 500-Year Existing 1434.00 159.16 169.00 169.97 0.016069 7.92 183.84 44.04 0.54

Reach 1 480 500-Year Proposed 1434.00 159.16 169.00 169.97 0.016069 7.92 183.84 44.04 0.54

Reach 1 430 OHW Existing 0.40 158.04 160.12 160.12 0.000001 0.02 18.45 11.60 0.00

Reach 1 430 OHW Proposed 0.40 158.04 160.12 160.12 0.000001 0.02 18.45 11.60 0.00

Reach 1 430 2-Year Existing 242.00 158.04 164.80 164.90 0.002597 2.54 95.73 24.34 0.21

Reach 1 430 2-Year Proposed 242.00 158.04 164.80 164.90 0.002597 2.54 95.73 24.34 0.21

Reach 1 430 5-Year Existing 342.00 158.04 165.49 165.64 0.003467 3.08 113.36 26.68 0.25

Reach 1 430 5-Year Proposed 342.00 158.04 165.49 165.64 0.003467 3.08 113.36 26.68 0.25

Reach 1 430 10-Year Existing 432.00 158.04 165.98 166.17 0.004230 3.52 126.95 29.16 0.27

Reach 1 430 10-Year Proposed 432.00 158.04 165.98 166.17 0.004230 3.52 126.95 29.16 0.27

Reach 1 430 25-Year Existing 573.00 158.04 166.58 166.84 0.005457 4.15 146.33 41.46 0.31

Reach 1 430 25-Year Proposed 573.00 158.04 166.58 166.84 0.005457 4.15 146.33 41.46 0.31

Reach 1 430 50-Year Existing 700.00 158.04 166.99 167.32 0.006434 4.67 170.02 77.74 0.34

Reach 1 430 50-Year Proposed 700.00 158.04 166.99 167.32 0.006434 4.67 170.02 77.74 0.34

Reach 1 430 100-Year Existing 844.00 158.04 167.39 167.79 0.007332 5.16 204.00 91.60 0.37

Reach River Sta Profile Plan Q Total Min Ch El W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl Flow Area Top Width Froude # Chl

(cfs) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)

Reach 1 430 100-Year Proposed 844.00 158.04 167.39 167.79 0.007332 5.16 204.00 91.60 0.37

Reach 1 430 500-Year Existing 1434.00 158.04 168.68 169.24 0.009566 6.47 351.42 137.89 0.43

Reach 1 430 500-Year Proposed 1434.00 158.04 168.68 169.24 0.009566 6.47 351.42 137.89 0.43

Reach 1 280 OHW Existing 0.40 160.00 160.11 160.12 0.014832 0.58 0.69 6.55 0.31

Reach 1 280 OHW Proposed 0.40 160.00 160.11 160.12 0.014832 0.58 0.69 6.55 0.31

Reach 1 280 2-Year Existing 242.00 160.00 163.96 164.18 0.010803 3.83 65.94 41.50 0.43

Reach 1 280 2-Year Proposed 242.00 160.00 163.96 164.18 0.010803 3.83 65.94 41.50 0.43

Reach 1 280 5-Year Existing 342.00 160.00 164.45 164.74 0.012252 4.36 91.88 63.92 0.47

Reach 1 280 5-Year Proposed 342.00 160.00 164.45 164.74 0.012252 4.36 91.88 63.92 0.47

Reach 1 280 10-Year Existing 432.00 160.00 164.80 165.13 0.013065 4.70 117.40 80.07 0.49

Reach 1 280 10-Year Proposed 432.00 160.00 164.80 165.13 0.013065 4.70 117.40 80.07 0.49

Reach 1 280 25-Year Existing 573.00 160.00 165.25 164.13 165.61 0.013587 5.08 156.74 93.03 0.51

Reach 1 280 25-Year Proposed 573.00 160.00 165.25 164.13 165.61 0.013587 5.08 156.74 93.03 0.51

Reach 1 280 50-Year Existing 700.00 160.00 165.55 164.60 165.95 0.013830 5.45 185.39 96.72 0.52

Reach 1 280 50-Year Proposed 700.00 160.00 165.55 164.60 165.95 0.013830 5.45 185.39 96.72 0.52

Reach 1 280 100-Year Existing 844.00 160.00 165.87 165.07 166.31 0.013914 5.80 216.69 100.59 0.53

Reach 1 280 100-Year Proposed 844.00 160.00 165.87 165.07 166.31 0.013914 5.80 216.69 100.59 0.53

Reach 1 280 500-Year Existing 1434.00 160.00 166.92 167.50 0.014393 6.95 329.15 113.41 0.56

Reach 1 280 500-Year Proposed 1434.00 160.00 166.92 167.50 0.014393 6.95 329.15 113.41 0.56

Reach 1 130 OHW Existing 0.40 156.86 157.21 157.11 157.23 0.026012 1.03 0.39 2.22 0.44

Reach 1 130 OHW Proposed 0.40 156.86 157.21 157.11 157.23 0.026012 1.03 0.39 2.22 0.44

Reach 1 130 2-Year Existing 242.00 156.86 160.14 160.14 160.91 0.061310 7.06 35.02 32.31 0.97

Reach 1 130 2-Year Proposed 242.00 156.86 160.14 160.14 160.91 0.061310 7.06 35.02 32.31 0.97

Reach 1 130 5-Year Existing 342.00 156.86 160.63 160.63 161.46 0.047239 7.39 55.01 48.18 0.89

Reach 1 130 5-Year Proposed 342.00 156.86 160.63 160.63 161.46 0.047239 7.39 55.01 48.18 0.89

Reach 1 130 10-Year Existing 432.00 156.86 160.98 160.98 161.85 0.042022 7.72 73.81 59.30 0.86

Reach 1 130 10-Year Proposed 432.00 156.86 160.98 160.98 161.85 0.042022 7.72 73.81 59.30 0.86

Reach 1 130 25-Year Existing 573.00 156.86 161.42 161.42 162.35 0.038665 8.24 102.46 73.07 0.85

Reach 1 130 25-Year Proposed 573.00 156.86 161.42 161.42 162.35 0.038665 8.24 102.46 73.07 0.85

Reach 1 130 50-Year Existing 700.00 156.86 161.75 161.75 162.73 0.036580 8.62 128.74 83.73 0.84

Reach 1 130 50-Year Proposed 700.00 156.86 161.75 161.75 162.73 0.036580 8.62 128.74 83.73 0.84

Reach 1 130 100-Year Existing 844.00 156.86 162.08 162.08 163.10 0.035362 9.03 157.49 94.02 0.84

Reach 1 130 100-Year Proposed 844.00 156.86 162.08 162.08 163.10 0.035362 9.03 157.49 94.02 0.84

Reach 1 130 500-Year Existing 1434.00 156.86 163.08 163.08 164.28 0.033894 10.43 267.31 125.79 0.86

Reach 1 130 500-Year Proposed 1434.00 156.86 163.08 163.08 164.28 0.033894 10.43 267.31 125.79 0.86

Reach 1 0 OHW Existing 0.40 155.00 155.23 155.15 155.24 0.010009 0.51 0.79 6.77 0.26

Reach 1 0 OHW Proposed 0.40 155.00 155.23 155.15 155.24 0.010009 0.51 0.79 6.77 0.26

Reach 1 0 2-Year Existing 242.00 155.00 157.58 156.76 157.68 0.010011 2.51 96.36 74.76 0.39

Reach 1 0 2-Year Proposed 242.00 155.00 157.58 156.76 157.68 0.010011 2.51 96.36 74.76 0.39

Reach River Sta Profile Plan Q Total Min Ch El W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl Flow Area Top Width Froude # Chl

(cfs) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)

Reach 1 0 5-Year Existing 342.00 155.00 157.94 157.02 158.05 0.010003 2.74 124.93 85.12 0.40

Reach 1 0 5-Year Proposed 342.00 155.00 157.94 157.02 158.05 0.010003 2.74 124.93 85.12 0.40

Reach 1 0 10-Year Existing 432.00 155.00 158.20 157.22 158.33 0.010013 2.90 148.81 92.90 0.40

Reach 1 0 10-Year Proposed 432.00 155.00 158.20 157.22 158.33 0.010013 2.90 148.81 92.90 0.40

Reach 1 0 25-Year Existing 573.00 155.00 158.56 157.48 158.71 0.010004 3.11 183.98 103.30 0.41

Reach 1 0 25-Year Proposed 573.00 155.00 158.56 157.48 158.71 0.010004 3.11 183.98 103.30 0.41

Reach 1 0 50-Year Existing 700.00 155.00 158.84 157.69 159.01 0.010001 3.27 213.81 111.36 0.42

Reach 1 0 50-Year Proposed 700.00 155.00 158.84 157.69 159.01 0.010001 3.27 213.81 111.36 0.42

Reach 1 0 100-Year Existing 844.00 155.00 159.12 157.91 159.30 0.010009 3.43 245.94 119.43 0.42

Reach 1 0 100-Year Proposed 844.00 155.00 159.12 157.91 159.30 0.010009 3.43 245.94 119.43 0.42

Reach 1 0 500-Year Existing 1434.00 155.00 160.02 158.59 160.26 0.010016 3.93 365.23 145.60 0.44

Reach 1 0 500-Year Proposed 1434.00 155.00 160.02 158.59 160.26 0.010016 3.93 365.23 145.60 0.44

F E D E R A L H I G H WAY A D M I N I S T R AT I O N

Eastern Federal Lands Highway Division

21400 Ridgetop Circle

Sterling, Virginia 20166