Des_Lacs_FINAL_Hydrualics_Report.pdf

Submitted to:

US Department of Transportation Federal Highway Administration Central Federal Lands Highway Division 1200 West Dakota Avenue Lakewood, Colorado 80228

FINAL Hydraulics Report CR 2 Bridge Replacement over the Des Lacs River

ND FLAP CR 2(1)

AECOM Project Number 60341735 March 30, 2016

AECOM FINAL Hydraulics Report CR 2 Bridge Replacement over Des Lacs River: ND FLAP 2 (1)

TOC-i

Table of Contents 1 Introduction............................................................................................................................ 1-1

1.1 Project Background and Objectives ......................................................................... 1-1

1.2 Project Area Description .......................................................................................... 1-2

1.3 Site Visit and Field Observations ............................................................................. 1-3

1.4 Bridge Design Criteria .............................................................................................. 1-3

1.5 Project Data ............................................................................................................ 1-3

2 Hydrologic & Hydraulic Analysis .......................................................................................... 2-1

2.1 Hydrologic Considerations ....................................................................................... 2-1

2.2 Hydraulic Considerations ......................................................................................... 2-1

2.3 Riprap Slope Protection and Bank Stability Measures .............................................. 2-2

2.4 Construction Considerations .................................................................................... 2-2

3 Summary ................................................................................................................................ 3-1

3.1 Variances Required ................................................................................................. 3-1

3.2 Summary of Recommendations ............................................................................... 3-1

4 References ............................................................................................................................. 4-1

Appendix Appendix A: Resources Appendix B: Hydrology Appendix C: Hydraulics Appendix D: Construction Plans

List of Figures Figure 1-1. Des Lacs Bridge Project Location ............................................................................................................... 1-1 Figure 1-2. Dam Structures Number 2 and 4 Locations................................................................................................. 1-2

List of Tables Table 2-1. Bridge Summary .......................................................................................................................................... 2-2

1-1

The Federal Lands Access Program (FLAP) is providing funding for work on public highways, roads, bridges, trails, and transit systems that provide access to Federal Lands. The FLAP scope of work (SOW) for this project is to perform environmental, engineering, hydraulic, geotechnical, right-of-way, surveying, mapping, and project management services toward delivery of 100% Plans, Specifications, and Estimates (PS&E) for the Federal Highway Administration (FHWA), Central Federal Lands Highway Division (CFL) for proposed improvements to Dec Lacs Refuge Bridge on County Route 2 (CR 2) Ward County, North Dakota (ND).

This report provides a brief overview of the key project elements and summarizes the hydrologic and hydraulic (H&H) analysis necessary for the proposed hydraulic improvements.

1.1 Project Background and Objectives

This project is generally described as replacing Bridge #51-107-08.2, on CR 2 over the Des Lacs River, between Des Lacs National Wildlife Refuge (NWR) and Kenmare, and is shown below in Figure 1-1. The project location is northwest ND, latitude 48.676438 north and longitude 102.093275 west.

Figure 1-1. Des Lacs Bridge Project Location Provided by Map data © 2014 Google

The existing bridge is 27 feet wide by 50 feet long and has a sufficiency rating of 67.5 (Scoping Report, 2014).

This bridge will be replaced with a wider structure to accommodate shoulders.

The proposed structure is 39.5 feet wide by 80 feet long. Ward County has indicated a desire to have the proposed bridge be similar to the Brickyard Road Bridge, which is downstream and was replaced in 2013. The Brickyard Road Bridge is a precast concrete girder structure on steel piles, and it is anticipated the Des Lacs Bridge will be similar. Roadway approach work is minimal and will consist of tying asphalt to the new bridge deck and installing approach guardrails.

1 Introduction

Des Lacs Bridge

1-2

The objective of this project is to evaluate existing H&H conditions and design a new bridge with more structural stability to mitigate potential damages.

1.2 Project Area Description

The project location is in an area that is influenced by Dam Structure Number 2, (upstream of the bridge) and Dam Structure Number 4 (downstream of the bridge). See Figure 1-2 for reservoir locations.

Figure 1-2. Dam Structures Number 2 and 4 Locations

CR 2 crosses the floodplain at a 90 degree angle, with the channel constricting at the bridge location. The Federal Emergency Management Agency (FEMA) Flood Insurance Rate Map (FIRM) shows a floodplain that is approximately 2,000 feet wide. Survey indicates that the slope from north to the upstream face of the bridge is

0.009 percent and south to the downstream face of bridge is 0.003 percent with the bridge location being the lowest point of the channel. The main channel varies from 20 feet to 50 feet wide. The main channel consists of fine- to medium-grained sand (D50 ~ 0.2 to 1.0 millimeters) and medium- to coarse-grained sand (D50 ~ 0.4 to 4.0 millimeters). Medium-sized rounded rock was identified on the channel banks. Three wetland areas have been identified (two on the north face of the bridge and one on the south face of the bridge). All three of the wetlands will be impacted by the project improvements.

As previously mentioned, the bridge location is between two regulated reservoirs (Dam Structures 2 and 4). The water surface level (WSEL) is subject to dam release rates and the WSEL of Middle Des Lacs Lake. Due to the controlled nature of the flows the “channel” that the bridge spans is more of a pooling area than a channel.

The flows conveyed in the channel have not overtopped the Des Lacs Bridge. Just west of the project, the Niobe Coulee convey flows that are not contained. These flows overtop CR1 and are conveyed along CR1 to a low point on CR2 immediately west of the bridge. Eventually, these flows will overtop the CR2 bridge deck.

Dam Structure Number 2 (North Structure)

Des Lacs Bridge

Dam Structure Number 4 (South Structure)

1-3

1.3 Site Visit and Field Observations

The CFL project team visited the project site in May 2014 and December 2015 to review the existing site conditions and define the SOW for the design of a replacement bridge. Photos from the site visit are included in the Appendix A-1.

As design progressed, verbal and email correspondence with Chad Zorn, Des Lacs NWR Manager yielded the following observations:

1. Dam Release Rates:

a. Although there is a Water Management Plan, the dam release rates could not be provided.

Release rates and detention are regulated by NWR staff with hands-on experience.

b. In the spring of 2015, the United States Geological Survey (USGS) measured the maximum release rate of the dam upstream of CR 2 at 200 cubic feet per second (cfs).

2. Water Conveyance:

a. Field observations noted that the channel has negligible velocities and is generally still or moves slowly.

b. In the spring, water generated from the Town of Kenmare pushes flows to the north. Otherwise, off-site flows are conveyed to the south.

3. Bridge Overtopping: There is no history of the bridge overtopping because of channel flows. In 2011, the Des Lacs Bridge did have water on the bridge deck; however, this occurred because of Niobe Coulee flows overtopping CR 1 and being conveyed to the CR 2 Bridge. The existing bridge adequately conveys flows in the channel.

4. Peak Release Rates/Reoccurrence Intervals: These have not been studied or documented and are unknown.

5. Measured WSELs are:

a. Typical target summertime elevation = 1784.50 feet

b. 2015 High WSEL = 1786.76 feet

c. 2011 Flood WSEL: South structure = 1789.70 feet and North structure = 1790.24 feet

6. Records from the years 1939 through 2015, noted WSELs higher than 1788 feet in the years 1969, 1970, and 2011 with the latter being the highest on record.

1.4 Bridge Design Criteria

These agencies will need to review and approve the bridge design:

Ward County Highway Department and Ward County Water Board Floodplain Coordinator: Amber Turnquest, also Ward County’s Planner North Dakota State Water Commission, and

CFL

The channel conveying flows under the bridge does not have channel characteristics (observed minimal velocity and previously discussed factors determine if water flows northerly or southerly) and as such, should not be evaluated using channel hydraulics. The bridge is spanning a “pool;” as velocities and storage capacity are determined by upstream and downstream structure release rates and backwater effects of the Middle Des Lacs Lake WSEL. As a result, a variance requested to use known and targeted WSEL, as opposed to design storm events.

In addition, this area is known for ice jam, which calls for a minimum of 5 feet of freeboard.

1.5 Project Data

Detailed mapping of the project corridor was completed by Wilson and Company and included a ground survey near the bridge and surveyed cross sections through the channel taken in spring 2015. The mapping products referenced the NAD83 horizontal datum and the NAVD88 vertical datum.

2-1

Below is an explanation of the approach used for hydraulic design. Initially, H&H calculations were considered, see Appendix B and C for preliminary calculations used for preliminary H&H analysis. However, it was determined the use of target water surface elevations were more appropriate as explained below.

2.1 Hydrologic Considerations

The contributing watershed area is approximately 602 square miles (mi2), originating in Canada and flowing to a series of channels, lakes, and reservoirs located in the Des Lacs NWR. In evaluating the watershed area and the Scope of Work (SOW), there was no consideration of attenuation of flow, ponding, dam release, or the backwater effects of the downstream reservoir. This requires an alternative reservoir routing approach (Environmental Protection Agency-Storm Water Management Model), which was beyond the scope of design so regression equations were used, although it is an oversimplified approach. Peak flows were determined using USGS’ software program National Streamflow Statistics (NSS) Version 6.1, which referenced USGS’ Water Resources Investigations Report 92-4020 regression equations, which can be found in Appendix B.

2.2 Hydraulic Considerations

Initial hydraulic analysis was conducted using peak flows from NSS; however, the HEC RAS, Version 4.1.0 model could not be calibrated to produce realistic results. For more information on modeling methods and assumptions, see Appendix C, as a reference only. A summary of outliers from the HEC RAS model included:

High Velocities: Observed conditions noted stagnate to slow moving water, the proposed model could not be calibrated to produce slow velocities

Drastic Fluctuations in Downstream and Upstream WSELs

This confirms that a routing alternative hydrologic analysis is required, one that is beyond the SOW for this project. As a result, it was agreed to use observed, real WSEL and to design freeboard based on the WSEL provided by Chad Zorn, NWR Manager. These WSELs are not associated with a storm event.

Typical target summertime elevation = 1784.50 feet (Design WSEL) High WSEL = 1790.24’ this was obtained from the 2011 Flood Event (Scour calculations WSEL)

The proposed improvements indicate that target and high WSELs would pass through the bridge. See Table 2-1 below. However, improvements could not accommodate maintaining or increasing the low chord elevations. The vertical profile and structure location was set based on (more specifics in Appendix C):

Proposed Structure Requirements:

o County’s preferred 80-foot-long bridge requires deeper structure depth o Reduce the amount of vertical curve on the bridge o Abutment placement requires a minimum 2.5 x h-pile widths to reduce stress overlap and potential construction issues Proposed Roadway Improvements: Vertical limitations are set to match existing just east of the railroad tracks and just west of the Town of Kenmare.

The proposed bridge clear span will be increased from 50 feet to 80 feet. The increase in span length will occur on the east end of the bridge. With the elimination of the interior pier and by clear spanning a wider opening, the proposed structure depth will be deeper. The difference in low chord depth ranges from lowering the low chord by

0.26 feet to raising it by 0.74 feet. At least 5 feet of freeboard is maintained using the target WSEL and at least

1.25 feet of freeboard for the high WSEL. The WSEL will not hit the proposed low chord elevation for either the target or high WSEL. Table 2-1 provides a summary of low chord elevations and freeboard heights.

2 Hydrologic & Hydraulic Analysis

2-2

Table 2-1. Bridge Summary

Classification Existing Proposed

Spans Double Single

Structure Depth (inches) Unknown 30” + 3” of asphalt + 1” tolerance = 34”

Low Chord Elevation (feet) NW: 1792.34, NE: 1792.29

SW: 1792.47, SE: 1792.36

NW: 1792.08. NE=1793.03

SW: 1791.49, SE=1792.43

Design/Target WSEL Freeboard (feet) NW: 7.84, NE: 7.79

SW: 7.97, SE: 7.86

NW: 7.58, NE: 8.53

SW: 6.99, SE: 7.93

Observed High WSEL Freeboard (ft) NW: 2.10, NE: 2.05

SW: 2.23, SE: 2.12

NW: 1.84, NE: 2.79

SW: 1.25, SE: 2.19

To minimize environmental impacts, there will be minimal grading in the channel so that the channel width will remain the same.

2.3 Riprap Slope Protection and Bank Stability Measures

The characteristics of the bridged waterway indicates reservoir ponding condition rather than open channel flows.

H&H has not been conducted and design is based on provided WSEL. Scour computations are not warranted or appropriate for the reservoir ponding condition impacting the bridge. The observed velocity while not zero is assumed to be very low and cannot be measured to justify scour conditions. Instead slope protection measures will be taken to protect the abutments slopes from erosion that may occur from possible wave action. Riprap abutment protection includes freeboard above the target WSEL. Class 3 Riprap (d50 = 12 inch), 2.0 feet deep on top of geotextile (Class 1, Type E) is proposed to be laid out along the proposed abutments per HEC 23, Figure

14.7 guidance.

This bridge has not been identified as a scour critical bridge. Because of the slow moving velocities, contraction and local scour have not been considered. There are no proposed piers, so pier scour is also not considered.

2.4 Construction Considerations

During construction, a temporary roadway diversion is required that will span the Des Lacs River just north of the bridge. The existing channel will be conveyed in corrugated metal pipes (CMPs). See Construction Plans for more details. Coordination with the NWR staff is required to make adjustments to release rates.

3-1

Itemized variances required and a summary of proposed recommendations are below.

3.1 Variances Required

A design variance is required for sizing the hydraulic opening of the proposed bridge. Instead of using a storm event, known WSEL will be used. Based on H&H analysis, it was agreed that the design will be based on observed WSEL, not on design storm event. This variance to design allows the target WSEL to be used, instead of the design event. The design/target WSEL will provide a minimum of 5 feet of freeboard; however, the high WSEL will provide a minimum of 1.25 feet of freeboard.

3.2 Summary of Recommendations

Bridge Configuration: The proposed bridge is a single-span structure with a lower low chord than the existing bridge. As a result of removing the existing pier, the proposed bridge structure will be deeper. In addition, the proposed bridge clear span length has been increased from 50 feet to 80 feet.

Bridge Location: The center of the proposed bridge is to be located approximately 9.5 feet east of where the center of the existing bridge is located.

Riprap Slope Protection and Bank Stability Measures: Hydraulic parameters are not available to support abutment protection requirements; however, Class 3 Riprap (d50 = 12 inch), 2.0 feet deep is proposed to be laid out per HEC 23, Figure 14.7 guidance along the proposed abutments using the high WSEL.

3 Summary

4-1

USDOT, FHWA, Federal Lands Highway Project Development and Design Manual, January 2014.

USGS, Water Resources Investigations Report 99-4020: Techniques for Estimating Peak-Flow Frequency relations for North Dakota Streams, 1992.

USACE, HEC RAS, Version 4.1.0, January 2010

FEMA, Ward County, North Dakota and Incorporated Areas Flood Insurance Rate Map, January 2000.

North Dakota State Water Commission, Article 89-14 Public Highway Stream Crossing, January 2015.

North Dakota Department of Health Division of Water Quality, Lake Water Quality Assessment for Upper Des Lacs Lake Ward and Burke Counties North Dakota, March 2006.

USDOT, Hydraulic Engineering Circular No. 18: Evaluating Scour at Bridges, Fifth Edition, April 2012.

USDOT, FHWA, Hydraulic Engineering Circular No. 23: Bridge Scour and Stream Instability Countermeasures:

Experience, Selection, and Design Guidance-Third Edition, Volume 2, September 2009.

FHWA, CFLHD, FLAP Des Lacs National Wildlife Refuge, Ward County, North Dakota, ND FLAP CR 2(1), CR 2 Bridge Replacement, June 2014.

4 References

AECOM

Appendix A: Resources A-1 Field Review Photos

A-2 Email Correspondence with Des Lacs NWR: Target and Observed WSEL

A-3 Roadway Options

A-4 Structure Recommendations for Bridge Design

A-5 Email Correspondence with Des Lacs NWR: Records of WSEL greater than 1788 feet kirkbridet Typewriter A1 Resources, 1

A1 Resources, 2

A1 Resources, 3

SalekM Text Box View upstream at east abutment kirkbridet

A1 Resources, 4

Downstream face

SalekM Text Box Downstream face, east abutment kirkbridet

A1 Resources, 5

Upstream view, west bank

SalekM Text Box Upstream view

SalekM Text Box Downstream face

SalekM Text Box Downstream face kirkbridet

A1 Resources, 6

Upstream face

SalekM Text Box Upstream face kirkbridet

A1 Resources, 7

Downstream view, west bank

SalekM Text Box Downstream view kirkbridet

A1 Resources, 8

A1 Resources, 9

Eggers, Tammy

From: Zorn, Chad <chad_zorn@fws.gov> Sent: Wednesday, August 12, 2015 1:00 PM To: Eggers, Tammy Subject: Re: FW: Bridge Design Standards

Hey Tammy ...... good talking with you the other day.

A few more tidbits of info for you.

Current water elevation (typical target summer time elevation) 1784.50.

High elevation for 2015 1786.76.

In 2011 .... it was the highest I've seen in my 15 years being around this area. Reading at structure #2 was

1789.70. Readings at #4 was 1790.24 The bridge that you are working on would be moving water from #2 to #4. So all of the water eventually made it under the current bridge. Again, it is never fast current under the bridge but it slowly moves down the channel between #2 and #4.

If you have any other questions, pls give me a call.

Thanks, Chad Zorn Refuge Manager

Des Lacs National Wildlife Refuge 42000 520th ST NW Kenmare, ND 58746 office (701)-385-4046 ext. 225 cell (701)-848-6616 email chad_zorn@fws.gov

On Mon, Aug 10, 2015 at 10:38 AM, Eggers, Tammy <Tammy.Eggers@aecom.com> wrote:

Tammy Eggers, PE

Drainage Engineer, Transportation

D 303.740.2702 C 303.807.4533

A2 Resources, 1

From: Eggers, Tammy Sent: Wednesday, August 05, 2015 8:38 AM To: 'Dana Larsen' Cc: Travis Schmit; Amber Turnquest; Kim Rossland Subject: RE: Bridge Design Standards

Dana, Amber, Travis, Thank you for your quick reply! The guidance is greatly appreciated. Yesterday, I came across a couple of other questions as the Des Lacs Bridge Replacement area is located in an area influenced by dams. Upstream of the bridge is Dam Number 2, just west of the bridge is Dam Number 3, and downstream of the bridge is Dam Number 4, please see figure below for bridge & dam locations. The bridge also spans a FEMA Zone A floodplain.

With the presence of dams, do you know/provide guidance on the following:

1. Release rates based on storm events

2. Monthly peak release rates.

3. Recommended design flow rates (Q25, Q50, Q100, Q200, Q500)

4. If the previous items cannot be provided, let’s call to discuss approach to determine hydrology (limited time to develop this)

5. History of floods or bridge overtopping (I read about this one in May 2013:

http://www.kenmarend.com/kenmare-news/features/runoff-quickly-turns-from-a-trickle-to-a-gush/)

6. Who regulates/owns/maintains the dams?

7. Any other considerations to bridge replacements, ie stream crossing permits, dam permits, etc

Thank you for your time & help, A2 Resources, 2

From: Dana Larsen [mailto:Dana.Larsen@co.ward.nd.us] Sent: Tuesday, August 04, 2015 4:22 PM kirkbridet

A2 Resources, 3

To: Eggers, Tammy Cc: Travis Schmit; Amber Turnquest; Kim Rossland Subject: RE: Bridge Design Standards

Tammy

1. Are there hydraulic design criteria that needs to be considered?

a. Ward County requires bridges meet at least a 25 year event on County Rural Roads and a 100 year event when located in an area that could affect a town our homes.

b. Link to State Water Commission requirements http://www.legis.nd.gov/information/acdata/pdf/89-14-01.pdf?20150804165353

2. Are there any other agencies that will need to review the bridge hydraulics?

a. Ward County Highway Department

b. Ward County Water Board

You can just send Travis and myself a copy of the hydraulic study and we will bring it to the Water Board for approval.

3. Is there a floodplain administrator that I need to be in coordination with?

a. Amber Turnquest, is the County Planner and is the County Flood Plain Coordinator. I have copied Amber in this email and she is located in our Office.

4. Are there any other considerations that you recommend me making?

a. Even though there are no homes that would be affected by water my desire would be for the bridge to be designed to accommodate a 100 year event

Dana G. Larsen, P.E.

Ward County Engineer kirkbridet

A2 Resources, 4 stahrj Oval stahrj Oval kirkbridet

A3 Resources, 1

A3 Resources, 2 stahrj Oval stahrj Oval kirkbridet

A3 Resources, 3

A3 Resources, 4

From: Vause, Maegan Sent: Monday, November 23, 2015 1:26 PM To: Eggers, Tammy Cc: Stahr, James; Salek, Matthew; Holst, Stephen Subject: RE: Des Lacs Bridge Location/Low Chord

I misspoke before. We would like the abutment 3’ WEST of current location, see correction below.

Maegan Vause D 303.376.2916 Maegan.Vause@aecom.com

AECOM

717 17th Street, Ste 2600 Denver, CO 80202 www.aecom.com

The AECOM offices of Environment, Federal Services, Planning, Design & Development, Transportation and Water have co-located to create One

AECOM.

From: Vause, Maegan Sent: Monday, November 23, 2015 1:24 PM To: Eggers, Tammy Cc: Stahr, James; Salek, Matthew; Holst, Stephen Subject: RE: Des Lacs Bridge Location/Low Chord

Hi Tammy, Per our conversation please see below the reason why the structures design team prefers option 5, placing the east abutment 3’ WEST of existing abutment.

We believe it would be best to offset the abutment 3’ west from its original location (Option 5) for the following reasons:

Reduce the amount of vertical curve on the bridge.

o There is no deck to account for vertical curve, must be accommodated with asphalt.

Per the geotech report a minimum spacing of 2.5x h-pile widths is recommended to reduce stress overlap, this is in reference to new piles but I think it is good practice and would reduce the potential construction issues related to the unknowns of the existing piles.

Due to structure weight and poor soil conditions 8 piles are required at each abutment. No survey is currently provided for location/spacing of current piles. Due to spacing requirements an additional pile may be required if abutment location remains the same.

Please let us know if you approve of the proposed location and we can move forward design.

Maegan

Maegan Vause D 303.376.2916 kirkbridet

A5 Resources, 1

Maegan.Vause@aecom.com

AECOM

717 17th Street, Ste 2600 Denver, CO 80202 www.aecom.com

The AECOM offices of Environment, Federal Services, Planning, Design & Development, Transportation and Water have co-located to create One

AECOM.

From: Vause, Maegan Sent: Thursday, November 19, 2015 11:41 AM To: Eggers, Tammy Cc: Stahr, James; Salek, Matthew; Holst, Stephen Subject: RE: Des Lacs Bridge Location/Low Chord

Tammy, See below the low chords I have calculated for Des Lacs. These low chords will be located at the South west end of the bridge. You are correct, due to the cross slope of the bridge the North end would be higher (0.5925’ higher). Based on initial design the structure depth is assumed to be 3.59875’. This includes: 30” Box Girder, 3” Asphalt, 3.55” for 1.5% cross slope (from CL to edge of deck) as well as an allowance for haunch depth and additional asphalt due to vertical curve on bridge.

Option 3: At existing abutment location:

South= 1789.787 North=1790.379

Option 4: 5’ East of Existing Abutment South= 1789.841 North=1790.433

The difference in low chords between option 3 & 4 is 5/8”

After speaking with Steve we believe it would be best to offset the abutment 3’ from its original location (Option 5), preferably to the West to reduce the amount of vertical curve on the bridge. Per the geotech report a minimum spacing of 2.5x h-pile widths is recommended to reduce stress overlap, this is in reference to new piles but I think it is good practice and would reduce the potential construction issues related to the unknowns of the existing piles.

Given the information provided in James email, below is the approximate low chords for places the abutment 3’ West of existing:

Option 5: 3’ West of Existing Abutment Location Approx. Low Coords:

South= 1789.754 North=1790.353 Difference in low chord of 3/8” between option 5 & option 3.

For all options 3, 4 & 5 the north side (high side) of the bridge is above the WSEL for the 2011 storm (1790.24). Given the 1.088% bridge slope the south end of the bridge will be below the WSEL for the following lengths:

Option 3: Low chord below WSEL for 24.10’ Option 4: Low chord below WSEL for 21.22’ Option 5: Low chord below WSEL for 25.85’ *Due to the varying haunch thickness and beam camber the actual lengths will be shorter.

Low chord at East in of Bridge:

kirkbridet

A5 Resources, 2

Option 3 = 1790.631, 4.695” of freeboard Option 4 = 1790.710, 5.64” of freeboard Option 5 = 1790.586, 4.152” of freeboard

Maegan

Maegan Vause D 303.376.2916 Maegan.Vause@aecom.com

AECOM

717 17th Street, Ste 2600 Denver, CO 80202 www.aecom.com

The AECOM offices of Environment, Federal Services, Planning, Design & Development, Transportation and Water have co-located to create One

AECOM.

From: Vause, Maegan Sent: Thursday, November 19, 2015 8:24 AM To: Eggers, Tammy Subject: RE: Des Lacs Bridge Location/Low Chord

Hi Tammy, I just got back from vacation. I will get up to speed and try to get those elevations to you sometime today.

Thanks, Maegan

Maegan Vause D 303.376.2916 Maegan.Vause@aecom.com

AECOM

717 17th Street, Ste 2600 Denver, CO 80202 www.aecom.com

The AECOM offices of Environment, Federal Services, Planning, Design & Development, Transportation and Water have co-located to create One

AECOM.

From: Eggers, Tammy Sent: Thursday, November 12, 2015 12:50 PM To: Stahr, James; Vause, Maegan; Holst, Stephen; Salek, Matthew Subject: RE: Des Lacs Bridge Location/Low Chord

James—thanks for the exhibit, that clarifies things.

Maegan—can you please confirm the low chord elevations on both the north & south approaches of the bridge. I was told that the substructure depth could be higher on the north approach.

kirkbridet

A5 Resources, 3

Matt—with the increased bridge opening, were you planning on doing channel improvements? It appears that there’ll be some wetland takes, especially since we should place riprap along the banks & through the abutments (see attached, it will need to happen which ever layout is chosen). Does Brian/environmental know that that is happening?

D 303.740.2702 C 303.807.4533

From: Stahr, James Sent: Thursday, November 12, 2015 12:15 PM To: Eggers, Tammy Subject: RE: Des Lacs Bridge Location/Low Chord

Tammy, I’ve added plan views for each case (see attached). The low chord elevation is based on a 3.59875’ offset of the profile which depicts the structure depth with a 1.5% cross slope at the bridge extent on the downslope edge. I circled the approximate location on the plan view for clarity.

James Stahr E.I.T.

Transportation Engineer D 303.376.2934 James.stahr@aecom.com

717 17th Street, Suite 2600 Denver, CO 80202-0202 T 303.228.3000 F 303.228.3001 Cisco 2702912 www.aecom.com

Please consider the environment before printing this email.

From: Eggers, Tammy Sent: Thursday, November 12, 2015 11:15 AM To: Stahr, James Subject: RE: Des Lacs Bridge Location/Low Chord

James, Just a couple of questions:

1. Is the Low Chord elevation at the centerline of the road or at the end of the road/bridge? I remember there being talk if the road was going to be crowned at 1-1.5%?

2. Can you please show a plan view so I can see if the channel is going to change?

Thanks, Tammy Eggers, PE Drainage Engineer, Transportation D 303.740.2702 C 303.807.4533 kirkbridet

A5 Resources, 4

From: Stahr, James Sent: Wednesday, November 11, 2015 3:38 PM To: Eggers, Tammy; Vause, Maegan; Holst, Stephen; Salek, Matthew Subject: RE: Des Lacs Bridge Location/Low Chord

Dang gremlins stole the PDF…

James Stahr E.I.T.

Transportation Engineer

Denver, CO 80202-0202 T 303.228.3000 F 303.228.3001 Cisco 2702912 www.aecom.com

Please consider the environment before printing this email.

From: Stahr, James Sent: Wednesday, November 11, 2015 3:25 PM To: Eggers, Tammy; Vause, Maegan; Holst, Stephen; Salek, Matthew Subject: Des Lacs Bridge Location/Low Chord

I’ve created a low chord matrix as a visual PDF (attached) to show the trade off with adjusting the location of the west abutment. Each profile shows the amount of vertical curve that would be on the bridge deck, the new low chord based on 1.5% cross slope, with the amount of the girder submerged for the 2011 Flood Event, and the most up to date roadway profile. Please let me know of anything else that will help determine an acceptable location.

James Stahr E.I.T.

Transportation Engineer

Denver, CO 80202-0202 T 303.228.3000 F 303.228.3001 Cisco 2702912 www.aecom.com

Please consider the environment before printing this email.

A5 Resources, 5

From: Zorn, Chad <chad_zorn@fws.gov> Sent: Wednesday, March 23, 2016 7:15 AM To: Eggers, Tammy Subject: Re: Des Lacs Bridge Flooding Question

Dug thru the narratives. It appears that since 1939, it has only been above 1788, 3 times. The years were 1969,1970 and 2011. Looks like 2011 was the highest on record.

Hope this helps.

Chad Zorn Refuge Manager

Des Lacs National Wildlife Refuge 42000 520th ST NW Kenmare, ND 58746 office (701)-385-4046 ext. 225 cell (701)-848-6616 email chad_zorn@fws.gov

On Thu, Mar 10, 2016 at 10:37 AM, Eggers, Tammy <Tammy.Eggers@aecom.com> wrote:

Chad, Thanks for the reply. It would be good to have, especially because the proposed low chord is a concerned, past records will be important to document decisions. I think that we’re a month out from getting another submittal out, if it’s possible to have this information prior to that, would be great

From: Zorn, Chad [mailto:chad_zorn@fws.gov] Sent: Wednesday, March 09, 2016 11:56 AM kirkbridet

A6 Resources,1

Appendix B: Hydrology This is for reference only and was not used for bridge design or hydrologic analysis

B-1 Bridge Hydrology: WRIR 99-4020

B-2 NSS Results: Temporary Roadway Diversion Culverts

Typewritten Text B.1 Hydrology, 1

Callout Project Location kirkbridet

B.1 Hydrology, 2

B.1 Hydrology, 3

Highlight kirkbridet

B.1 Hydrology, 4

Highlight kirkbridet

B.1 Hydrology, 5

Project Location just downstream of Upper Des Lacs Lake kirkbridet

B.1 Hydrology, 6

DesLacsPeakFlows.nss.txt National Streamflow Statistics Program Version 6.1 Based on Techniques and Methods Book 4-A6 Equations from database C:\Program Files (x86)\NSS\NSS_v6_2015-02-26.mdb Updated by KGR 2/20/2015 3:17:03 PM Added LC11IMP impervious percent from NLCD 2011

Site: Dec Lacs, North_Dakota User:

Date: Wednesday, August 26, 2015 02:09 PM

Equations for North_Dakota developed using English units

Rural Estimate: Rural 1 Basin Drainage Area: 604 square miles 1 Region

Region: Region_C (Williams-Sether, Tara, 1992, Techniques for Estimating Peak-Flow Frequency Relations for North Dakota Streams: U.S. Geological Survey Water-Resources Investigations Report 92-4020, 57 p. ) Contributing_Drainage_Area = 604 square miles Stream_Slope_10_and_85_Method = 3 feet per mi Crippen & Bue Region 11

Results for: Rural 1

Equations used:

PK2 = 4.08* (CONTDA)^(0.638)* (CSL10_85)^(0.348)

PK10 = 22.3* (CONTDA)^(0.665)* (CSL10_85)^(0.275)

PK15 = 29.4* (CONTDA)^(0.668)* (CSL10_85)^(0.263)

PK25 = 39.7* (CONTDA)^(0.67)* (CSL10_85)^(0.249)

PK50 = 56.3* (CONTDA)^(0.671)* (CSL10_85)^(0.232)

PK100 = 75.6* (CONTDA)^(0.672)* (CSL10_85)^(0.219)

PK500 = 129* (CONTDA)^(0.676)* (CSL10_85)^(0.196)

Value, Standard Equivalent Statistic ft3/s Error, % Years

PK2 356 100 2

PK10 2130 71 5.2

PK15 2830 77 6.3

PK25 3810 68 7.5

PK50 5340 68 9

PK100 7110 69 10

PK500 12100 75 12

maximum: 151000 (for C&B region 11) kirkbridet Typewritten Text B.2 Hydrology, 7 kirkbridet

Used to size temporary roadway diversion culverts

Appendix C: Hydraulics HEC-RAS info is for reference only and was not used for bridge design or hydraulic results

C-1 Hydraulics Modeling Approach

C-2 HEC-RAS: Existing and Proposed Conditions Standard Table

C-3 HEC-RAS: Existing and Proposed Conditions Profile

C-4 HEC-RAS: Existing Conditions Cross Sections

C-5 HEC-RAS: Proposed Conditions Cross Sections

C-6 Hydraulic Toolbox: Riprap Sizing

C-7 HY8: Temporary Roadway Diversion Culvert Sizing

Preliminary hydraulic models were developed using the US Army Corp of Engineers’ (USACE) Hydrologic Engineering Center River Analysis Software version 4.1 (HEC-RAS) of the CR2 bridge to assess flow conveyance and freeboard height. The model limits extends roughly 100 ft upstream and 150 ft downstream of the bridge. A total of 7 cross sections were used for the field survey to represent the channel geometry through the reach. The locations of the cross sections are show in Figure 3-1, overlaid on Google Maps.

Figure 3-1. HECRAS Cross Section Locations

A single 80 ft span bridge will be considered for design. The County requested the design. Because of pooling and the influences of the Structures 2 and 3, a known Water Surface Elevation (WSEL) was coded in for the downstream boundary condition of 1784.50 ft. After running a subcritical flow, an upstream WSEL was determined and coded as the upstream boundary condition for each of the storm events. Both existing and proposed conditions models were ran with the mixed flow regime.

The cross sections have obstructions placed in them because just west of the railroad tracks in Structure Number 3 and the Niobe Coulee which do not contribute to this bridge project’s hydraulics.

The channel conveying flows through the bridge does not have channel characters (observed minimal velocity and previously discussed factors determine if water flows northerly or southerly) and should not be evaluated using channel hydraulics. The bridge is spanning a “pool,” as velocities and storage is determined by Structure 2 and 4’s release rates and backwater effects of the Middle Des Lacs Lake WSEL just downstream of the bridge.

As a result, it is recommended to use observed WSEL and design from known target and high WSEL and provide the minimum 2’ of freeboard, per Central Federal Lands Highway Division (CFLHD) criteria. It is also recommended to keep the proposed low chord at the same or higher elevation than the existing low chord.

In preparing the models, the following are assumed:

1. The 25 year storm event passes through the bridge at a low pool WSEL (1784.5),

2. The low pool WSEL is the tailwater elevation,

3. Head loss is expected at the bridge, Hydraulic Analysis Methods

CR2

CR1

CR2

kirkbridet

C.1 Hydraulic Analysis Methods, 1

0 50 100 150 200 250 300

DesLacsBridge Plan: ExistingBack 9/3/2015

Main Channel Distance (ft)

E le va tio n (ft

Legend

WS Q100

WS Q25

Ground

.7

0.

1.

5.

9.

9.

9.

DesLacs DesLacs

4. Bridge headwater elevation is not to exceed the high pool WSEL, and

5. The high pool WSEL is reflective of reluctant backwater after any occurrence has passed through

6. Table 3-1 provides a summary of HEC-RAS model inputs.

Table 3-1. HEC-RAS Model Inputs

Item Existing Conditions Proposed Conditions Comments

Channel Manning’s n 0.035 0.035 Bed material consists of gravel, sand, and cobbles

Bank Manning’s n Left & Right = 0.045 Left & Right = 0.045 Established vegetation

Bridge Deck Width 27’ 36’

Bridge Depth 1.83’ 3.50’

Piers 1-2 ft wide None

1.1 Existing Conditions Model

See Figure 3-21 and Figure 3-3 for the profile and downstream cross section of the existing bridge.

Figure 3-2. Existing Profile

Bridge low chord elevation = 1792.33’

Bridge deck elevation = 1793.33’ kirkbridet

C.1 Hydraulic Analysis Methods, 2

0 500 1000 1500 2000 2500 3000

DesLacsBridge Plan : ExistingBack 9/3/2015 River = DesLacs Reach = DesLacs RS = 175.2631 BR Existing Bridge

Station (ft)

E le va tio n (ft

Legend

WS Q100

WS Q25

Ground

Ineff

Bank Sta

.045 .035 .045

Figure 3-3. Existing Bridge Upstream Bridge Face

Based on the figures above, up to the 100 year storm event is conveyed through the bridge.

1.2 Proposed Conditions Model

With the elimination of the single pier and spanning a wider opening, the proposed bridge deck will be thicker and have a low chord that is 2.66’ lower than the existing low chord of (1792.33’). However, because of the pooling nature of the channel, this should have minimal impacts on increasing or decreasing the WSEL. However, preliminary floodplain modeling shows variations with rises and decreases in the 100 year WSEL.

The proposed bridge includes a 2 horizontal to 1 vertical spill through abutments with a span length of 76 ft. See Figure 3-4 and Figure 3-5 for profile and cross sections.

Table 3-1 provides a summary of the hydraulics at the upstream face of bridge for both the existing and proposed conditions.

elevation = 1792.33’ kirkbridet

C.1 Hydraulic Analysis Methods, 3

DesLacsBridge Plan: ProposedBack 9/3/2015

Main Channel Distance (ft)

E le va tio n (ft

Legend

WS Q100

WS Q25

Ground

.7

0.

1.

5.

9.

9.

9.

DesLacs DesLacs

0 500 1000 1500 2000 2500 3000

DesLacsBridge Plan : ProposedBack 9/3/2015 River = DesLacs Reach = DesLacs RS = 175.2631 BR Proposed Bridge

Station (ft)

E le va tio n (ft

Legend

WS Q100

WS Q25

Ground

Ineff

Bank Sta

Figure 3-4. Proposed Profile

Figure 3-5. Proposed Bridge Upstream Bridge Face elevation = 1789.63’

Bridge deck elevation = 1793.33’

Bridge low chord elevation = 1789.63’ kirkbridet

C.1 Hydraulic Analysis Methods, 4

AECOM Preliminary Hydraulics Recommendations Report

September 22, 2015

Table 3-2 provides a summary of the hydraulics at the upstream face of bridge for both the existing and proposed conditions. The proposed bridge does not satisfy the minimum 2 feet of freeboard. In addition, the proposed bridge is not able to convey the high pool WSEL and water will be in the bridge deck should waters not be released prior to the low chord elevation.

Table 3-2. Summary of Hydraulic Model Results for 25-year Storm Event

Q25 Design Flow = 3810 cfs Minimum Freeboard = 2 ft (per PPDM, freeboard is measured at the upstream face of the bridge) Deck Thickness = 2H: 1V Sloping riprap abutment protection

Table 3-3 provides a summary of 100 year floodplain hydraulics. As previously mentioned, there are decreases and rises in the floodplain. However, the channel does not have channel characteristics and an alternate method of analysis is recommended.

Table 3-3. Floodplain Hydraulics: Existing and Proposed 100-yr WSEL and Velocities

HEC-RAS Cross Section

Span (ft) (at abutment face)

Pier Width

(ft)

Abutment Slope (H:V)

Up WSEL Face of Bridge

Low Chord Elevation

(ft)

Freeboard (ft)

Deck Elevation

(ft)

Approx.

Grade Rise

(ft)

Low Pool WSEL (ft)

High Pool WSEL (ft)

Existing Bridge 50 2 1:1 1788.61 1792.29 3.68 1793.29 - 1784.50 1790.24 Proposed Bridge 76 - 2:1 1788.29 1789.63 1.34 1793.29 0 1784.50 1790.24

HEC-RAS Cross Section

100-year Existing

WSEL

(ft)

100-year Proposed

WSEL

(ft)

Difference in WSEL from Existing (ft)

100-year Existing Velocity

(fps)

100-year Proposed Velocity

(fps)

Difference in Velocity from Existing (fps)

279.278 1797.01 1793.17 -3.84 1.32 3.47 2.15

239.2776 1797.01 1793.11 -3.90 1.32 3.84 2.52

199.277 1794.98 1791.42 -3.56 10.92 10.50 -0.42

175.2631 Bridge

151.2491 1790.47 1789.07 -1.40 18.51 14.40 -4.11

100.4892 1786.73 1787.26 0.53 21.05 15.72 -5.33

68.74427 1786.96 1788.89 1.93 14.80 7.41 -7.39

16.14429 1787.73 1787.76 0.03 9.92 9.83 -0.09 kirkbridet

C.1 Hydraulic Analysis Methods, 5

HEC-RAS River: DesLacs Reach: DesLacs 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) DesLacs 279.278 Q2 EBack 356.00 1781.33 1785.08 1782.70 1785.10 0.000239 1.20 295.97 118.71 0.13 DesLacs 279.278 Q2 PBack 356.00 1781.33 1784.83 1782.70 1784.86 0.000320 1.33 267.10 114.32 0.15 DesLacs 279.278 Q10 EBack 2130.00 1781.33 1789.20 1784.69 1789.28 0.000393 2.19 974.18 230.86 0.19 DesLacs 279.278 Q10 PBack 2130.00 1781.33 1787.79 1784.69 1787.94 0.000982 3.13 680.65 187.26 0.29 DesLacs 279.278 Q25 EBack 3810.00 1781.33 1792.14 1785.81 1792.22 0.000218 2.17 1778.75 296.98 0.15 DesLacs 279.278 Q25 PBack 3810.00 1781.33 1789.57 1785.81 1789.77 0.001026 3.59 1062.65 246.27 0.30 DesLacs 279.278 Q50 EBack 5340.00 1781.33 1794.50 1786.63 1794.56 0.000120 1.98 4140.13 2214.19 0.12 DesLacs 279.278 Q50 PBack 5340.00 1781.33 1791.25 1786.62 1791.45 0.000705 3.53 1519.63 284.82 0.26 DesLacs 279.278 Q100 EBack 7110.00 1781.33 1797.01 1787.68 1797.03 0.000038 1.32 9905.00 2367.81 0.07 DesLacs 279.278 Q100 PBack 7110.00 1781.33 1793.17 1787.66 1793.36 0.000460 3.47 2091.40 310.53 0.22 DesLacs 279.278 Q500 EBack 12100.00 1781.33 1803.38 1789.45 1803.38 0.000008 0.79 25538.36 2600.00 0.03 DesLacs 279.278 Q500 PBack 12100.00 1781.33 1800.90 1789.45 1800.91 0.000017 1.08 19304.44 2459.54 0.05

DesLacs 239.2776 Q2 EBack 356.00 1780.96 1785.05 1785.09 0.000267 1.58 224.72 61.83 0.15 DesLacs 239.2776 Q2 PBack 356.00 1780.96 1784.80 1784.84 0.000333 1.70 209.23 61.23 0.16 DesLacs 239.2776 Q10 EBack 2130.00 1780.96 1789.11 1789.24 0.001147 2.99 712.23 232.95 0.30 DesLacs 239.2776 Q10 PBack 2130.00 1780.96 1787.45 1787.85 0.003114 5.10 418.05 128.21 0.50 DesLacs 239.2776 Q25 EBack 3810.00 1780.96 1792.11 1792.20 0.000361 2.46 1582.37 329.65 0.19 DesLacs 239.2776 Q25 PBack 3810.00 1780.96 1789.29 1789.69 0.003144 5.03 757.09 241.85 0.50 DesLacs 239.2776 Q50 EBack 5340.00 1780.96 1794.49 1794.55 0.000162 2.10 3909.64 2221.55 0.13 DesLacs 239.2776 Q50 PBack 5340.00 1780.96 1791.12 1791.40 0.001410 4.24 1266.83 306.61 0.36 DesLacs 239.2776 Q100 EBack 7110.00 1780.96 1797.01 1797.02 0.000044 1.32 9615.46 2310.19 0.07 DesLacs 239.2776 Q100 PBack 7110.00 1780.96 1793.11 1793.33 0.000703 3.84 1921.04 350.49 0.27 DesLacs 239.2776 Q500 EBack 12100.00 1780.96 1803.38 1803.38 0.000008 0.78 25249.98 2581.29 0.03 DesLacs 239.2776 Q500 PBack 12100.00 1780.96 1800.90 1800.91 0.000019 1.08 18912.08 2524.83 0.05

DesLacs 199.277 Q2 EBack 356.00 1780.61 1784.92 1782.78 1785.06 0.001170 2.99 118.92 38.37 0.30 DesLacs 199.277 Q2 PBack 356.00 1780.61 1784.79 1781.89 1784.83 0.000303 1.69 210.55 58.83 0.16 DesLacs 199.277 Q10 EBack 2130.00 1780.61 1788.17 1786.53 1789.09 0.004047 7.70 276.61 55.91 0.60 DesLacs 199.277 Q10 PBack 2130.00 1780.61 1787.21 1784.63 1787.74 0.002162 5.84 364.70 68.57 0.45 DesLacs 199.277 Q25 EBack 3810.00 1780.61 1790.77 1788.42 1792.05 0.003321 9.08 419.53 191.08 0.58 DesLacs 199.277 Q25 PBack 3810.00 1780.61 1788.33 1786.39 1789.47 0.003923 8.58 444.31 73.10 0.61 DesLacs 199.277 Q50 EBack 5340.00 1780.61 1792.82 1789.80 1794.38 0.002955 10.04 532.06 293.09 0.57 DesLacs 199.277 Q50 PBack 5340.00 1780.61 1789.71 1787.68 1791.19 0.004049 9.75 547.92 108.41 0.64 DesLacs 199.277 Q100 EBack 7110.00 1780.61 1794.98 1791.19 1796.83 0.002672 10.92 651.13 2222.13 0.56 DesLacs 199.277 Q100 PBack 7110.00 1780.61 1791.42 1788.95 1793.13 0.003540 10.50 677.37 226.05 0.62 DesLacs 199.277 Q500 EBack 12100.00 1780.61 1800.70 1794.61 1803.14 0.002082 12.53 965.44 2451.01 0.53 DesLacs 199.277 Q500 PBack 12100.00 1780.61 1799.38 1791.76 1800.77 0.001220 9.43 1282.81 2387.06 0.40

DesLacs 175.2631 Bridge

DesLacs 151.2491 Q2 EBack 356.00 1780.89 1784.70 1784.90 0.002074 3.63 97.97 36.11 0.39 DesLacs 151.2491 Q2 PBack 356.00 1780.89 1784.76 1784.81 0.000364 1.78 199.88 59.50 0.17 DesLacs 151.2491 Q10 EBack 2130.00 1780.89 1786.56 1786.78 1788.72 0.014867 11.79 180.70 49.96 1.09 DesLacs 151.2491 Q10 PBack 2130.00 1780.89 1787.00 1787.60 0.002635 6.20 343.33 68.64 0.49 DesLacs 151.2491 Q25 EBack 3810.00 1780.89 1788.20 1788.65 1791.46 0.014439 14.50 262.68 54.24 1.13 DesLacs 151.2491 Q25 PBack 3810.00 1780.89 1787.66 1789.15 0.005856 9.79 389.32 71.33 0.74 DesLacs 151.2491 Q50 EBack 5340.00 1780.89 1789.37 1790.15 1793.59 0.015038 16.47 324.17 60.86 1.18 DesLacs 151.2491 Q50 PBack 5340.00 1780.89 1787.86 1787.80 1790.58 0.010374 13.23 403.50 72.13 0.99 DesLacs 151.2491 Q100 EBack 7110.00 1780.89 1790.47 1791.58 1795.79 0.015877 18.51 384.16 99.07 1.24 DesLacs 151.2491 Q100 PBack 7110.00 1780.89 1789.07 1789.07 1792.29 0.010098 14.40 493.85 82.29 1.00 DesLacs 151.2491 Q500 EBack 12100.00 1780.89 1793.12 1794.94 1801.12 0.015551 22.73 535.22 241.70 1.29 DesLacs 151.2491 Q500 PBack 12100.00 1780.89 1789.14 1791.79 1798.28 0.028338 24.27 498.56 83.40 1.67

DesLacs 100.4892 Q2 EBack 356.00 1781.06 1784.70 1784.78 0.000846 2.26 157.27 62.46 0.25 DesLacs 100.4892 Q2 PBack 356.00 1781.06 1784.70 1784.78 0.000846 2.26 157.27 62.46 0.25 DesLacs 100.4892 Q10 EBack 2130.00 1781.06 1786.78 1785.56 1787.36 0.009762 6.14 346.69 194.17 0.81 DesLacs 100.4892 Q10 PBack 2130.00 1781.06 1786.78 1787.36 0.009762 6.14 346.69 194.17 0.81 DesLacs 100.4892 Q25 EBack 3810.00 1781.06 1785.75 1787.32 1790.06 0.034828 16.67 228.49 73.66 1.67 DesLacs 100.4892 Q25 PBack 3810.00 1781.06 1787.67 1788.42 0.008803 6.94 549.33 237.45 0.80 DesLacs 100.4892 Q50 EBack 5340.00 1781.06 1786.46 1787.84 1791.73 0.089113 18.42 289.82 163.98 2.44 DesLacs 100.4892 Q50 PBack 5340.00 1781.06 1788.32 1789.21 0.007798 7.57 705.30 243.96 0.78 DesLacs 100.4892 Q100 EBack 7110.00 1781.06 1786.73 1788.38 1793.61 0.115193 21.05 337.81 189.94 2.78 DesLacs 100.4892 Q100 PBack 7110.00 1781.06 1787.26 1788.38 1791.10 0.057493 15.72 452.26 234.12 1.99 DesLacs 100.4892 Q500 EBack 12100.00 1781.06 1787.26 1789.79 1798.35 0.165775 26.72 452.89 234.15 3.39 DesLacs 100.4892 Q500 PBack 12100.00 1781.06 1787.69 1789.79 1795.08 0.085967 21.81 554.84 237.62 2.52

DesLacs 68.74427 Q2 EBack 356.00 1781.17 1784.68 1784.75 0.000807 2.20 161.65 64.62 0.25 DesLacs 68.74427 Q2 PBack 356.00 1781.17 1784.68 1784.75 0.000807 2.20 161.65 64.62 0.25 DesLacs 68.74427 Q10 EBack 2130.00 1781.17 1786.63 1785.48 1787.06 0.006874 5.25 405.40 220.96 0.68 DesLacs 68.74427 Q10 PBack 2130.00 1781.17 1786.63 1785.48 1787.06 0.006874 5.25 405.40 220.96 0.68 DesLacs 68.74427 Q25 EBack 3810.00 1781.17 1787.56 1786.90 1788.14 0.006025 6.12 623.05 244.84 0.68 DesLacs 68.74427 Q25 PBack 3810.00 1781.17 1787.56 1786.90 1788.14 0.006011 6.11 623.53 244.86 0.67 DesLacs 68.74427 Q50 EBack 5340.00 1781.17 1786.73 1787.44 1789.15 0.036756 12.47 428.15 224.34 1.59 DesLacs 68.74427 Q50 PBack 5340.00 1781.17 1788.24 1787.43 1788.95 0.005444 6.73 793.39 249.86 0.67 DesLacs 68.74427 Q100 EBack 7110.00 1781.17 1786.96 1787.97 1790.36 0.046399 14.80 480.42 231.94 1.81 DesLacs 68.74427 Q100 PBack 7110.00 1781.17 1788.89 1787.97 1789.75 0.005524 7.41 959.52 264.49 0.69 DesLacs 68.74427 Q500 EBack 12100.00 1781.17 1787.48 1789.33 1793.71 0.067046 20.03 603.99 243.90 2.24 DesLacs 68.74427 Q500 PBack 12100.00 1781.17 1787.90 1789.33 1792.43 0.040187 17.07 708.99 247.83 1.78

DesLacs 16.14429 Q2 EBack 356.00 1781.36 1784.50 1783.31 1784.67 0.002352 3.34 106.74 51.21 0.41 DesLacs 16.14429 Q2 PBack 356.00 1781.36 1784.50 1783.31 1784.67 0.002352 3.34 106.74 51.21 0.41 DesLacs 16.14429 Q10 EBack 2130.00 1781.36 1785.68 1785.68 1786.50 0.015477 7.25 293.65 181.68 1.01 DesLacs 16.14429 Q10 PBack 2130.00 1781.36 1785.68 1785.68 1786.50 0.015477 7.25 293.65 181.68 1.01 DesLacs 16.14429 Q25 EBack 3810.00 1781.36 1786.47 1786.47 1787.62 0.013899 8.59 443.59 196.39 1.01 DesLacs 16.14429 Q25 PBack 3810.00 1781.36 1786.47 1786.47 1787.62 0.013938 8.60 443.19 196.35 1.01 DesLacs 16.14429 Q50 EBack 5340.00 1781.36 1787.12 1787.12 1788.46 0.013117 9.30 573.92 215.72 1.01 DesLacs 16.14429 Q50 PBack 5340.00 1781.36 1787.12 1787.12 1788.46 0.013096 9.30 574.34 215.85 1.00 DesLacs 16.14429 Q100 EBack 7110.00 1781.36 1787.73 1787.75 1789.26 0.012831 9.92 716.49 240.52 1.01 DesLacs 16.14429 Q100 PBack 7110.00 1781.36 1787.76 1787.76 1789.26 0.012496 9.83 723.32 241.45 1.00 DesLacs 16.14429 Q500 EBack 12100.00 1781.36 1788.91 1789.17 1791.08 0.014354 11.82 1023.50 287.50 1.10 kirkbridet

C.2 HECRAS Standard Table, 6

HEC-RAS River: DesLacs Reach: DesLacs (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) DesLacs 16.14429 Q500 PBack 12100.00 1781.36 1789.17 1789.17 1791.05 0.011760 11.01 1099.02 295.83 1.01 kirkbridet

C.2 HECRAS Standard Table, 7

DesLacsBridge Plan: 1) EBack 9/9/2015 2) PBack 9/9/2015

Main…