Amend_0002_Atch_1_Redacted_Final_Design_Houghton_Dam_Demo_0002.pdf

Prepared for:

U.S. Fish and Wildlife - Region 6

134 Union Boulevard Lakewood, Colorado 80225

HOUGHTON DAM REMOVAL

SAND LAKE NATIONAL WILDLIFE REFUGE

DAMID SD01191

REGION 6 LOW HARZARD POTENTIAL DAM

SAND LAKE NATIONAL WILDLIFE REFUGE

COMPLEX

BROWN, COUNTY

SOUTH DAKOTA

Prepared by:

May 2021

Houghton Dam Removal 100-percent Design Report

Page ii

SAND LAKE NATIONAL WILDLIFE REFUGE

HOUGHTON DAM REMOVAL

DESIGN SUMMARY REPORT

DESIGN SUBMITTAL

TABLE OF CONTENTS

TABLE OF CONTENTS ................................................................................................. ii LIST OF TABLES .......................................................................................................... ii LIST OF FIGURES .........................................................................................................iii LIST OF APPENDICES .................................................................................................iii

1.0 BACKGROUND

2.0 PROJECT FEATURES

3.0 DATA COLLECTION

4.0 HYDRAULIC DESIGN

4.1 Inflow Hydrology

4.2 Reservoir Routing and Breach Sizing Analysis

4.3 Downstream Inundation Analysis

4.4 Sedimentation Analysis

5.0 OTHER DESIGN CONSIDERATIONS

5.1 Permitting

5.2 Remove Existing Service Spillway

5.2 Riprap Sizing

6.0 CONSTRUCTION CONSIDERATIONS

6.1 Dewatering Considerations

7.0 REFERENCES

LIST OF TABLES

Table 1 Summary of Alternatives and Selection

Table 2 Summary of Inflow Hydrology

Table 3 Summary of 2D HEC-RAS Modeling Results

Table 4 Summary of Cross-section Downstream

Table 5 Construction Cost Opinion Bid Tab

Page iii

LIST OF FIGURES

Figure 1 Houghton Dam Breach Scenarios

Figure 2 Houghton Dam Inundation Limits

LIST OF APPENDICES

Appendix A Design Drawings

Appendix D Field Photos

Appendix E Riprap Sizing

Https://D.Docs.Live.Net/5d9425036c38d18f/Desktop/Today/Designreport_March2020.Docx

1.0 BACKGROUND

Houghton Dam was constructed in the 1930s by the Civilian Conservation Corps (CCC), and is located in Brown County, South Dakota. Houghton Dam is currently classified as a small-sized, low-hazard potential dam, that was built across the James River to impound and enhance Mud Lake. Mud Lake is approximately 5,300 acres and provides habitat to thousands of waterfowl, white pelicans, shorebirds, franklin gulls, and other colonial nesting birds as well as 60 different species of fish. The current embankment dam is owned and operated by the U.S. Fish and Wildlife Service (USFWS) and is located on the

Sand Lake National Wildlife Refuge (see the vicinity and location maps provided on the drawings provided in Appendix A).

Houghton Dam is an earth embankment with a crest length of approximately 6,400 feet, a structural height of approximately 7 feet and an active normal high-water storage of 7,809-acre feet. The dam has a 110-foot-long water control structure that serves as the service spillway and a low area along the embankment near the left abutment that acts as the auxiliary spillway. Currently, the stoplog service spillway structure and access road bridge are in need of replacement. A bridge inspection completed in 2018, indicated that the existing structure has significant concrete cracking and spalling on the bridge deck as well as on the support walls. Additionally, the existing structure does not allow for floating debris to pass through it, thus resulting in large masses of debris piling up and restricting the flow through the structure. The current water control structure creates a hazardous condition when the staff must remove the stoplogs. When significant debris accumulates, staff members cannot remove the stoplogs from the crest of the spillway and must climb down in front of the structure to remove the debris.

In recent years, high river levels have caused frequent overtopping of Houghton Dam, which thus has resulted in extensive damage to the existing embankment and service spillway. The existing dam was renovated approximately 8 years ago and due to consecutive wet seasons, that renovated work and financial investment has been virtually lost. Based on the significant deterioration of the existing water control structure and the construction cost and life cycle cost for the structure replacement, the USFWS contracted

Wheeler to complete an alternatives analysis evaluation and develop alternatives including the potential for breaching the existing structure to address the identified deficiencies at the dam. Wheeler identified five alternatives and evaluated each of the alternative’s ability to adequately address the dam safety issues; their construction and long-term stability; sedimentation concerns; water management operations, wildlife habitat; and their expected future maintenance work. The alternatives and evaluation summary is provided in Table 1. Based on discussions with FWS, Alternative No. 4 was selected as the preferred alternative. This document supports the design concepts and assumptions used to decommission Houghton Dam. The design drawings and specifications are provided as Appendix A and B, respectively, for a singular breach which is the preferred alternative.

Table 1 – Summary of Alternatives and Selection Alternative No. & General

Description Evaluation 1 – Continue General Maintenance and Repair Auto Tour Route

Eliminated from consideration as this alternative does not address the dam safety deficiencies, and only repairs the auto tour route in the short term.

2 – Replace Existing Service Spillway

Eliminated from consideration as this alternative only addresses the deficiencies of the existing spillway structure by replacing structure in like kind. It does not address dam safety deficiencies and long-term maintenance issues.

3 – Address the Dam Safety Deficiencies

This alternative was not selected because of the expected maintenance issues associated with meeting the required FWS qualifications for a low hazard dam which include cost to raise and enlarge the dam.

4 – Remove and Breach Dam at Service Spillway

This is the preferred alternative. This alternative eliminates the identified dam safety deficiencies and provides the best long-term solution.

5 – Multiple Breach Locations This alternative was not selected as it really does not provide any additional benefit beyond Alternative 4.

2.0 PROJECT FEATURES

The decommissioning of Houghton Dam will remove the dam from the FWS dam inventory and remove the dam as an auto tour route. Removing the dam and route will reduce annual maintenance and eliminate the need for inspections. The key project features of the removal of the dam include:

1. Demolishing the 110-foot-long service spillway structure and disposing of the concrete off-site.

2. Excavating a smooth trapezoidal channel where the removed service spillway was located. The breach channel should be along the existing dam crest, with a bottom width of 150-feet, side slopes of 3 Horizontal (H) : 1 Vertical (V).

3. The longitudinal slope of the breach will tie into the existing ground elevation at

1282.5.

4. The breach will be armored with riprap protection along the invert and side slopes for length of 30-feet. A median rock size of Class A gradation will be used for the armoring.

Final Design Report

3.0 DATA COLLECTION

Topographic data of the project site and downstream hazards was obtained from two different sources:

• Surveying and Mapping, LLC completed a topographic land survey and bathymetric survey upstream and downstream of Houghton Dam. The land survey included the service spillway structure and downstream structures for

State Road 10, County Road 7A, and Columbia Dam. The bathymetric was completed to ground elevations of Mud Lake and Sand Lake near Houghton

Dam. The survey data was provided in North Dakota State Plan Coordinates using North American Vertical Datum of 88 (NAVD88).

• 1.4-meter Statewide LiDAR derived elevation data obtained from the South

Dakota GIS Hub acquired by USACE St. Louis District. The LiDAR elevation uses NAVD88 and was flown in 2010.

4.0 HYDRAULIC DESIGN

4.1 INFLOW HYDROLOGY

A frequency analysis of historic runoff data was used to estimate the 100-year Average

Recurrence Interval (ARI) peak discharge at Houghton Dam. This method was selected because the Houghton Dam drainage basin is large, approximately 2,180 square miles, and contains several upstream regulated dams that discharge into the James River. The

USGS stream gage (USGS 06470878: James River at ND-SD State Line) used for the analysis is located roughly 12 miles north-northeast of Houghton Dam (upstream) along the James River and has 38 years of daily streamflow data available.

Wheeler performed a USGS method for fitting a Log Pearson Type III frequency distribution to historic data from USGS 06470878 with the Annual Maximum Series (AMS) approach were employed along with an estimate of the regional skew coefficient (-0.38) taken from a map of regional skew coefficients within “Bulletin 17B: Guidelines for determining flood flow frequency” (U.S. Water Resources Council, 1982).

Table No. 2 summaries the results of the flood frequency analysis completed at Houghton

Dam.

Table 2 – Summary of Inflow Hydrology

Average Recurrence Interval

Peak Discharge (cfs)

2-year 1,362 5-year 3,181 10-year 4,883 25-year 7,635 50-year 10,128 100-year 13,000 200-year 16,302

4.2 RESERVOIR ROUTING AND BREACH SIZING ANALYSIS

A two-dimensional (2D) unsteady flow HEC-RAS Version 5.0.7 model (USACE, 2019) was developed to design the proposed breach dimensions at Houghton Dam. The breach dimensions were evaluated in accordance with FWS’s guidance for decommissioning low hazard dams (FWS, 2015). According to the FWS guidance, the size of the breach should be sufficient to pass the 100-year flood peak discharge (assuming no initial reservoir storage) with a maximum reservoir depth of six feet and the breach width should not be less than the bottom width of the original natural channel at the dam site. However, Houghton Dam is located on the James River, which is a mainstem river with constant flow; therefore, instead of assuming no initial reservoir storage, Wheeler assumed an initial and constant reservoir storage at Elevation 1286.52. This elevation is the normal reservoir elevation maintained and controlled by Columbia Dam located approximately 2 miles downstream of Houghton Dam. Using a two-dimensional model will more accurately capture the tailwater and downstream reservoir routing that occurs at James River to help identify the preferred dam breach size and associated maximum depths.

Wheeler evaluated three different dam breach sizes: 150-foot breach, 350-foot breach and 870-foot breach. The different breach sizes were selected from areas where the breach could easily tie into the natural ground downstream of the dam, per decommissioning requirements. The natural ground was determined by using aerial imagery, survey data and LiDAR. Figure No. 1 shows the different breach sizes evaluated in the model as well as their downstream tie in. Each of the breaches were evaluated for the 2-year, 5-year, 10-year, 25-year and 100-year peak discharges discussed in Section

4.1. The peak discharge was applied conservatively by developing an inflow hydrograph the same shape as a similar peak discharge event previously seen at the James River stream gage directly upstream of Houghton Dam and used in Section 4.1. The inflow hydrographs are provided in Appendix C.

A two-dimensional surface roughness of 0.05 was added to the entire 2D area to represent a Manning’s roughness for vegetated waterways and wetlands (DWR, 2020). The downstream inundation limits are mostly contained within the designated lakes and channel ways; therefore, Wheeler only applied a single roughness to the downstream inundation area. Three downstream bridge structures were added to the 2D flow area at

State Road 10, Columbia Dam, and 396th Avenue. The culvert dimensions and invert elevations were obtained from the survey data, LiDAR and field measurements taken during a site visit. Additional breaklines were added to the model at applicable areas to capture high and low areas within the inundation limits. A constant stage elevation of

1286.52 was used as the downstream boundary condition, added approximately 4 miles downstream of Columbia Dam. This boundary condition was used to represent the controlling water surface elevation at the dam but placed far enough downstream to not impact the water surface elevations between the Houghton and Columbia Dam.

Table No. 3 summarizes the results for the different breach scenarios evaluated in the hydraulic model. Due to the downstream constraints at State Road 10 and Columbia Dam, the 5-year storm event will overtop Houghton Dam during the 150 foot and 350 foot breach scenarios, but not the 870 foot breach. Whereas the 2-year flood will not overtop the dam during any of the breach scenarios and was selected as the inflow design flood (IDF) for

Houghton Breach. As shown in the table, the differences in head water (Mud Lake water surface elevation minus Sand Lake water surface elevation) are less than 6 feet for each of the breach scenarios which meets the decommissioning criteria. Due to the downstream constraints, minimal benefits are received from constructing a larger breach; therefore, Wheeler selected the 150-foot breach as the designed breach. The drawings in Appendix

A provide the existing spillway structure, proposed breach location as well as a profile and cross-sections of the breach.

Table 3 – Summary of 2D HEC-RAS Modeling Results

Parameter

Storm Event 2-year (1,360 cfs)

5-year (3,181 cfs)

10-year (4,883 cfs)

25-year (7,635 cfs)

100-year (13,000 cfs)

Peak Breach Flow (cfs)

150 ft Breach 1,129 1,969 2,436 2,642 3,122

350 ft Breach 1,233 2,375 3,118 3,482 4,390

870 ft Breach 1,281 2,556 3,494 4,137 5,104

Mud Lake WSE (feet)

150 ft Breach 1290.6 1291.8 1293.0 1293.7 1295.9 350 ft Breach 1290.3 1291.9 1293.0 1293.7 1295.9 870 ft Breach 1290.1 1292.0 1293.0 1293.7 1295.9

Sand Lake WSE (feet)

150 ft Breach 1289.7 1291.7 1293.0 1293.7 1295.9 350 ft Breach 1289.8 1291.9 1293.0 1293.7 1295.9 870 ft Breach 1289.8 1292.0 1293.0 1293.7 1295.9

Head Water (Mud Lake – Sand

Lake)

150 ft Breach 0.9 0.1 0.0 0.0 0.0 350 ft Breach 0.5 0.0 0.0 0.0 0.0 870 ft Breach 0.3 0.0 0.0 0.0 0.0

Max Overtopping Depth at

Houghton Dam, Crest El 1291.6

(feet)

150 ft Breach -1.0 0.2 1.4 2.1 4.3 350 ft Breach -1.3 0.3 1.4 2.1 4.3

870 ft Breach -1.5 0.4 1.4 2.1 4.3

4.3 DOWNSTREAM INUNDATION ANALYSIS

Also, as part of the FWS decommissioning guidance, Wheeler needs to demonstrate that no downstream structures are adversely impacted due the proposed dam breach. Wheeler used the 2D HEC-RAS model discussed in Section 4.2 to evaluate the downstream inundation limits for Houghton Dam based on the existing dam features and the proposed breach. The modeled runs where evaluated for the 100-year peak discharge and 2-year peak discharge. Figure No. 2 shows the downstream inundation limits and Table No. 4 summarizes the results for a cross-section located just upstream of Columbia Dam. The table values demonstrate that minimal differences are expected between the existing conditions and proposed conditions because of the downstream restrictions at State Road

10. Wheeler concluded that no adverse impacts are expected after the dam is decommissioned.

Table 4 – Summary of Cross-section Downstream

Parameter Storm Event 2-year 100-year

Max Flow (cfs) Existing Conditions 819 9,641

150 ft Breach 850 9,639

Max Depth (feet) Existing Conditions 3.1 8.8 150 ft Breach 3.2 8.8

Max Velocity (fps) Existing Conditions 0.2 0.6 150 ft Breach 0.2 0.6

Max Water Surface Elevation (ft)

Existing Conditions 1288.9 1294.5

150 ft Breach 1289.0 1294.5

4.4 SEDIMENTATION ANALYSIS

Sedimentation was considered during the alternative’s evaluation completed by Wheeler

(Wheeler, 2020). As presented in a USGS sedimentation study in 2003 (USGS, 2003), Mud Lake is continuing to experience sedimentation increases due to the surrounding agricultural lands and deposits in the reservoir. However, none of the considered alternatives will provide a significant reduction in the sedimentation issues associated with

Mud Lake due to the downstream constriction at State Road 10 and Columbia Dam. The downstream restrictions limit water surface head and velocity through the river system which is needed to flush sediments downstream.

5.0 OTHER DESIGN CONSIDERATIONS

5.1 PERMITTING

The U.S. Fish and Wildlife Service prepared and submitted an environmental assessment to their regional office on May 14, 2021. Resources analyzed in the EA include:

• Wildlife (including threatened, endangered, and sensitive species, migratory birds and raptors, and large game)

• Vegetation Resources

• Wetlands

• Floodplains

• Cultural and Historical Resources

• Land Use

No formal public meeting was held, but the draft EA was released to the Public for review.

No public comments were received. A finding of no significant impact (FONSI) was prepared and has been submitted to the FWS regional office for signature.

Additionally,

• The FWS completed intra-service Section 7 consultation for threatened and endangered species in March 2021. The FWS determined that the project would have “no effect” on federally threatened or endangered species.

• ERO Resources on behalf of FWS is currently in the process off completing the

Section 106 consultation for cultural and historic resources. Two historic resources

(Houghton Dam and a segment of the Auto Tour Road) were documented during the survey. ERO will recommend that both resources are not eligible for listing in the National Register of Historic Places.

• ERO Resources, on behalf of the FWS has prepared a preconstruction notification

(PCN) for submittal to the U.S. Army Corp of Engineers (Corps) to comply with

Section 404 of the Clean Water Act. Previous conversations with the Corps indicated that the project could be authorized under a Section 404 NWP (likely

NWP 3 for maintenance). The draft PCN is currently in review by the FWS and will be sent to the Corp following FWS review.

5.2 REMOVE EXISTING SERVICE SPILLWAY

The removal of the existing service spillway is shown on the design drawings provided in

Appendix A. As discussed in Section 1, during the field visit in July 2020, significant concrete deterioration was observed on the structure. Wheeler has designed the breach to remove the existing structure entirely and extend the breach an additional 20-feet to a total breach bottom width of 150-feet.

5.2 RIPRAP SIZING

The design includes armoring along the breach to eliminate any potential erosion during the 100-year storm event and day-to-day wave erosion. Appendix E provides detailed riprap sizing calculations using depths and velocities obtained from the HEC-RAS model described in Section 4.3. Based on those calculations, Wheeler designed a Class A riprap gradation per South Dakota Department of Transportation Standard

Specifications.

6.0 CONSTRUCTION CONSIDERATIONS

6.1 DEWATERING AND STREAM DIVERSION CONSIDERATIONS

The Construction Drawings do not include temporary reservoir control concepts to control reservoir inflows during construction. Design of the dewatering and stream diversion provisions will be the responsibility of the construction contractor. The timing of this project will be critical for dewatering Mud Lake during construction. Houghton dam is located directly on the James River between the two reservoir pools in Mud Lake and Sand Lake. Large river inflows will impact construction both upstream and downstream due to tailwater effects. Therefore, it is recommended that construction be completed when flows in the James River are less than 100 cfs. With flows less than

100 cfs, this will reduce the need for an extensive or elaborate cofferdam system at both the upstream and downstream side to complete the removal of the structure. As the river inflows increase, the cost to install and maintain the necessary cofferdam to complete the removal construction will increase exponentially. One dewatering consideration that could be considered for construction for flows greater than 100 cfs would be to breach or cut a channel in the low flow area near the left abutment around

Station 60+00. This could potentially divert flows in the James River and minimize flows in the construction area.

7.0 REFERENCES

1. Colorado Office of the State Engineer, Department of Natural Resources, Division of Water Resources , Dam Safety Branch, (DWR, 2020), Guidelines for Hydrologic Hazard Analysis, January 7, 2020.

2. Survey and Mapping Inc. (SAM, 2019), Field Survey completed by SAM, October 2019.

3. U.S. Army Corps of Engineers St. Louis District (USACE, 2020), 1.4-meter Statewide LiDAR South Dakota GIS Hub, Flown 2010 and 2011, website:

https://lidar.swc.nd.gov/

4. U.S. Army Corps of Engineers (USACE, 2019), Hydrologic Engineering Center River Analysis System (HEC-RAS) Version 5.0.7, March 219.

5. U.S. Bureau of Reclamation (USBR, 1989) Flood Hydrology Manual, First Edition 1989, Prepared by Arthur Cudworth Jr.

6. U.S. Fish and Wildlife Service, (FWS, 2015), Guidance for Decommissioning U.S.

Fish and Wildlife Service Low Hazard Dams, October 2015.

7. U.S. Fish and Wildlife Service, (FWS, 2010), Intermediate SEED Inspection Report Bone Hill Dam, Prepared by URS Group, Inc., January 28, 2011.

8. U.S. Geological Survey. (USGS, 2003), Sedimentation Rates in the Marshes of Sand Lake National Wildlife Refuge, April 2, 2003.

9. U.S. Geological Survey (USGS, 2020), StreamStats Version 4.4.0, website:

https://streamstats.usgs.gov/ss/

10. U.S. Geological Survey, (USGS, 1998), Techniques for Estimating Peak-Flow Magnitude and Frequency Relations for South Dakota Streams, 1998.

11. U.S. Fish and Wildlife Service (USFWS, 2020), Endangered, Threatened, Proposed and Candidate Species. http://ecos.fws.gov/ipac/.

12. W. W. Wheeler & Associates, Inc. (Wheeler, 2020), Houghton Dam Conceptual Alternatives Analysis, Prepared for USFWS.

https://lidar.swc.nd.gov/ https://streamstats.usgs.gov/ss/ http://ecos.fws.gov/ipac/

Appendix A

Design Drawings

K

K

K

K K

K K

K K

K K

KKKK

Sand Lake

Mud Lake

Houghton Dam

Model Termination at Sand Lake

Breach Alternatives

Low Level on Left Abutment

870 FT

150 FT

350 FT

+0

10+00

+0

+0

+0

+0

+0

+0

+0

+0

+0

+0

+0

0 1,000 2,000 Feet

FIGURE 1SE

PT

EM

BE

R

U.S. FISH &

WILDLIFE

SERVICE

Sand Lake National Wildlife Refuge Houghton Dam Removal

Breach Scenarios

1772.34

State Road 10

114th Street

Weismantel Grade

6th

Av e.

Sand Lake

Mud Lake

Houghton Dam

Columbia Dam

Ja me s R ive r

Refuge Headquarters

Re fug eB ou nd ar y

+0

0+ 00

10 +0 0

+0

+0

+0

+0

+0

+0

+0

+0

+0

+0

+0

5+ 00

0 12,000 24,000 Feet

FIGURE 2SE

P

TE

M

B E

R

U.S FISH &

WILDLIFE

SERVICE

Sand Lake National Wildlife Refuge Houghton Dam Removal

Inundation Limits

1772.34

Refuge Boundary

Proposed (150-ft breach) 10-year Inundation Limits

Proposed (150-ft breach) 100-year Inundation Limits

Existing 10-year Inundation Limits

Existing100-year Inundation Limits

Existing 10-year Inundation Limits

SAND LAKE NATIONAL

WILDLIFE REFUGE

SAND LAKE NATIONAL

WILDLIFE REFUGE

HOUGHTON DAM

PIERRE

LOCATION MAP

STATE MAP

(N.T.S.)

FISH AND WILDLIFE SERVICE

UNITED STATES DEPARTMENT OF THE INTERIOR

REGION 6 ENGINEERING - DENVER, COLORADO

DESIGNED:

DATE:

DRAWN:

DRAWING NO. SHEET 1 OF

CHECKED:

VICINITY MAP

NO SCALE

APPROVAL SIGNATURES

ANY PRINT ACCOMPANYING THIS INVITATION TO BID MAY BE A REDUCED

REPRODUCTION OF THE WORKING DRAWINGS. IF LINE BELOW DOES NOT

MEASURE SIX INCHES IN LENGTH, THE INDICATED SCALES ARE TO BE

ADJUSTED ACCORDINGLY.

NOTE TO BIDDERS:

REGIONAL ENGINEER

ASS'T. REGIONAL DIR.

DATE

PROGRAM SUPERVISOR

FACILITIES

SAFETY/IND HYGIENIST

CULTURAL RESOURCES

DATE

DATE

DATE

DATE

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SAND LAKE NATIONAL

WILDLIFE REFUGE

BROWN COUNTY SOUTH DAKOTA

HOUGHTON DAM REMOVAL

LOCATION MAPS AND

DRAWING INDEX

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HOUGHTON DAM REMOVAL

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SHEET

NUMBER SHEET TITLE

1 LOCATION MAPS AND DRAWING INDEX

2 ABBREVIATIONS, LEGEND, AND SITE ACCESS

3 EXISTING PLAN AND PROFILE

4 BREACH PLAN, PROFILE, AND CROSS-SECTION

5 EAST AND WEST ACCESS GATE

0 500 1000 2000 3000 Scale in Feet

SIOUX FALLS

COLUMBIA

HECLA

WESTPORT

FREDERICK

CLAREMONT

NORTH DAKOTA

SOUTH DAKOTA

MUD LAKE

SAND LAKE

SAND LAKE NATIONAL

WILDLIFE REFUGE

BOUNDARY

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DE

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NT

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IN

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TH

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FISH AND WILDLIFE

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SERVICE

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U.S. FISH & WILDLIFE SERVICE

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SERVICE

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AutoCAD SHX Text U.S.

0 2000 5000 10000 15000 Scale in Feet

SAND LAKE NATIONAL

WILDLIFE REFUGE

SAND LAKE

S2

A S2

INDICATES CROSS SECTION LOCATION. "A"

REFERS TO CROSS SECTION DESIGNATION. THE

NUMBER "S2" REFERS TO THE SHEET NUMBER

WHERE THE SECTION IS SHOWN.

INDICATES DETAIL LOCATION. THE NUMBER 6

REFERS TO THE DETAIL DESIGNATION. THE

NUMBER S2 REFERS TO THE SHEET NUMBER

WHERE THE DETAIL IS SHOWN.

CENTERLINE

MAJOR 5 FT CONTOUR INTERVAL

WITH ELEVATION IN FEET

MINOR 1 FT CONTOUR INTERVAL

NEW CONCRETE

EXISTING

CONCRETE

NATURAL GROUND

FILTER SAND

STEEL

EMBANKMENT

BACKFILL

SELECT FILL

NORTH ARROW

CONTROL

POINT/MONUMENT

BEDROCK

CUT SLOPE

FILL SLOPE

STRUCTURAL

SLOPE

LEGEND

PROPERTY BOUNDARY

APPROX. WATER OR WETLANDS LIMITS

DRAIN GRAVEL

RIPRAP

BACKFILL

CONCRETE

GROUT

BASECOURSE

A.B. = ANCHOR BOLT

ACB = ARTICULATED CONCRETE BLOCKS

ADDL = ADDITIONAL

APPROX. = APPROXIMATELY

B.O.H. = BOTTOM OF HOLE

BF = BOTTOM FACE

BL = BOTTOM LAYER

BM = BENCHMARK

BR = BOTTOM ROW

BTWN = BETWEEN

CFS = CUBIC FEET PER SECOND

CI - CAST IRON

CJ = CONSTRUCTION JOINT

CLR. = CLEAR

CMP = CORRUGATED METAL PIPE

CMU = CONCRETE MASONRY UNIT

CONC. = CONCRETE

CP = CONTROL POINT

CRJ = CONTROL JOINT

CTJ = CONTRACTION JOINT

CTR. = CENTER OR CENTERS

℄ = CENTERLINE

D = NORMAL DIAMETER OF

DI = DUCTILE IRON

DIPS = DUCTILE IRON PIPE SIZE

DR = DIMENSION RATIO

D/S = DOWNSTREAM

db = NOMINAL DIAMETER

DIA. = DIAMETER

DEMO = DEMOLISH

DET. = DETAIL

DIAG. = DIAGONAL

DWG. = DRAWING

DWL. = DOWEL

E. = EASTING

EA. = EACH

EC = EACH CORNER LENGTHS OF BARS

EF = EACH FACE

EJ = EXPANSION JOINT

EL = ELEVATION (IN FEET)

ELL = HDPE ELBOW

EMBED = EMBEDDED/EMBEDMENT

EQ. SPC. = EQUALLY SPACED OR EQUAL

SPACES

ER = EACH ROW

ES = EACH SIDE

EW = EACH WAY

EXIST = EXISTING

F.G. = FINAL GRADE

FF = FAR FACE

EL. = FINISH

FLG = FLANGE

FR = FAR ROW

FS = FAR SIDE REINFORCING BAR

FTG. = FOOTING

GA = GAUGE

GALV. = GALVANIZED

GR. = GRADE

GRP = GLASSFIBER REINFORCED PLASTICS

H = HORIZONTAL

HDPE = HIGH DENSITY POLYETHYLENE

H.R. = HAND RAIL

HK. = HOOK

HSS = HOLLOW STRUCTURAL SECTION

I.D. = INSIDE DIAMETER

IF = INSIDE FACE

INV. = INVERT

IR = INSIDE ROW

Ld = DEVELOPMENT LENGTH

LCD = LEFT CHIMNEY DRAIN

LLV = LONG LEG VERTICAL

LOD = LEFT OUTLET DRAIN

LTD = LEFT TOE DRAIN

MAX. = MAXIMUM

MFR. = MANUFACTURER

MIN. = MINIMUM

MJ = MECHANICAL JOINT

ML = MIDDLE LAYER

MP = MONITORING POINT

MR = MIDDLE ROW

N. = NORTHING OR NORTH

NO. = NUMBER

NAVD = NORTH AMERICAN VERTICAL DATUM

NGVD = NATIONAL GEODETIC VERTICAL

DATUM

NHWL = NORMAL HIGH WATER LINE

N.T.S. = NOT TO SCALE

NF = NEAR FACE

NR = NEAR ROW EQ.

NS = NEAR SIDE

O.C. = ON CENTER

O.D. = OUTSIDE DIAMETER

O.H.P. = OVER HEAD POWER

OF = OUTSIDE FACE

OPP = OPPOSITE

OR = OUTSIDE ROW

PC = POINT OF CURVATURE

P.D. = PLAIN DOWELS

P.I. = POINT OF INTERSECTION

P.R.C. = POINT OF REVERSE CURVATURE

PT = POINT OF TANGENCY

PE = PLAIN END

⅊ = PLATE

PLCS = PLACES

PROJ = PROJECTION

PVC = POLY VINYL CHLORIDE

R = RADIUS

RCD = RIGHT CHIMNEY DRAIN

REQD = REQUIRED

REINF. = REINFORCEMENT

ROD = RIGHT OUTLET DRAIN

RSP = RIVETED STEEL PIPE

RTD = RIGHT TOE DRAIN

S = SLOPE

SCH. = SCHEDULE

SDR = STANDARD DIMENSION RATIO

SECT. = SECTION

SEO = COLORADO DIVISION OF WATER

RESOURCES, OFFICE OF THE STATE

ENGINEER

SIM. = SIMILAR

SPC. = SPACE OR SPACES

SPY. = SPILLWAY

SQ. = SQUARE

SS = STAINLESS STEEL

STA. = STATION

STD = STANDARD

STL. = STEEL

SYM. = SYMMETRICAL

T.&B. = TOP AND BOTTOM

T.O. = TOP OF

T.O.W. = TOP OF WALL

TF = TOP FACE

THK = THICK

THRD = THREADED

TL = TOP LAYER

TR = TOP ROW OF REINFORCING BAR

TYP. = TYPICAL

U.N.O. = UNLESS NOTED OTHERWISE

U/S = UPSTREAM

UV = UNIFORMLY VARYING

V = VERTICAL

VCP = VITRIFIED CLAY PIPE

W = WIDE FLANGE STRUCTURAL BEAM

W/ = WITH

W/O = WITHOUT

WP = WORK POINT

W.S. = WATER SURFACE

W.S.A. = WATER STOP TYPE A

WSP = WELDED STEEL PIPE

WTP = WATER TREATMENT PLANT

SURVEY NOTES:

1. TOPOGRAPHIC SURVEY DATA WAS COLLECTED BY SURVEYING AND

MAPPING, LLC. ON OCTOBER 16, 2020

2. HORIZONTAL PROJECT COORDINATES ARE SOUTH DAKOTA STATE

PLANE NORTH, NORTH AMERICAN DATUM 1983 (NAD 83). THE

GEODETIC NETWORK WAS TIED TO CONTINUOUSLY OPERATING

REFERENCE STATIONS.

3. PROJECT VERTICAL CONTROL IS BASED ON NORTH AMERICAN

VERTICAL DATUM 1988 (NAVD 88)

DESIGNED DRAWN CHECKED DATE DRAWING NO. SHEET

OF

SUB-SHEETSAND LAKE NATIONAL

HOUGHTON DAM REMOVAL

CBM SAA SLJ 5/14/21 6R-SD-168-19-018 2 5

ABBREVIATIONS, LEGEND, AND SITE ACCESS G2

R:

\1

0\

\1

2.

.0 1_

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_D am

_T itl eI I\

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\1

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-0

-0 6-

1:

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FS

ABBREVIATIONS

MUD LAKE

NOTES:

1. PRIMARY CONSTRUCTION ACCESS IS FROM THE WEST SIDE.

CONTRACTOR CAN ACCESS FROM EAST OF AUTO ROAD IF NECESSARY.

2. STAGING AREA LOCATED IN FIELD WEST OF STATION 0+00.

AUTO TOUR

ROAD

SERVICE

SPILLWAY

STAGING AREA

SITE ACCESS

ROAD

WEST ENTRANCE GATE

(REF. DWG. C3)

EAST ENTRANCE GATE

(REF. DWG. C3)

AutoCAD SHX Text

-3 5+

-3 0+

-2 0+

-1 0+

0+

+0

+0

+0

+0

+0

60+00

66+00

EL

EV

AT

IO

N (F

EE

T)

EL

EV

AT

IO

N (F

EE

T)

PROFILE VIEW OF STOPLOG STUCTURE

14+00 15+00 16+00 17+00 18+00

8.8'

SERVICE SPILLWAY

DESIGNED DRAWN CHECKED DATE DRAWING NO. SHEET

OF

SUB-SHEETSAND LAKE NATIONAL

HOUGHTON DAM REMOVAL

CBM SAA SLJ 5/14/21 6R-SD-168-19-018 3 5

EXISTING PLAN AND PROFILE C1

R:

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2.

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_D am

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0 200 500 1000 1500 Scale in Feet

MUD LAKE

LOW

FLOW

AREA

SAND LAKE

RE

FU

GE

B

OU

ND

AR

Y

PLAN OF EXISTING CONDITIONS

EXISTING CONCRETE

STOPLOG STRUCTURE

PRECONSTRUCTION

GROUND SURFACE

AUTO TOUR ROAD

130.0'

SECONDARY ACCESS/

DEWATERING LOCATION

PRIMARY

ACCESS

NOTES:

1. DEMOLISH AND DISPOSE OF EXISTING STOPLOG

STRUCTURE. STRUCTURE IS 130'L x 9'H x 11'W.

2. IF CONSTRUCTED WITH RIVER INFLOWS GREATER

THAN 100 CFS, LOW FLOW AREA MAY BE

EXCAVATED FOR WATER DIVERSION.

3. CONTRACTOR SHALL VERIFY INVERT ELEVATIONS

OF STRUCTURE PRIOR TO DEMOLITION.

WETLAND

BOUNDARY

(TYP.)

STAGING AND

STOCKPILE

(220'x 100')

EAST ENTRANCE GATE

(REF. DWG. C3)

WEST ENTRANCE GATE

(REF. DWG. C3)

+0

+0

+0

+0

+0

0.

-3.0H:1V

-3.0H:1V

0.

0%

-1 .5

H :1

V

-1 .5

H :1

V

CP1

CP2

CP3

CP4

EL

EV

AT

IO

N (F

EE

T)

EL

EV

AT

IO

N (F

EE

T)

PROFILE VIEW OF EMBANKMENT BREACH

14+50 15+00 16+00 17+00 17+50

EL

EV

AT

IO

N (F

EE

T)

EL

EV

AT

IO

N (F

EE

T)

16+00

0.020.040.060.080.0100.0 0.0 -20.0 -40.0

0 10 20 40 60 Scale in Feet

DESIGNED DRAWN CHECKED DATE DRAWING NO. SHEET

OF

SUB-SHEETSAND LAKE NATIONAL

HOUGHTON DAM REMOVAL

CBM SAA SLJ 5/14/21 6R-SD-168-19-018 4 5

BREACH PLAN, PROFILE, AND CROSS-SECTION C2

R:

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PRECONSTRUCTION

GROUND SURFACE

150.0'

EXISTING STRUCTURE

TO BE REMOVE

PLAN VIEW OF

EMBANKMENT BREACH

24" CLASS A

GRADATION RIPRAP

OVER 6" BEDDING

24" CLASS A

GRADATION RIPRAP

OVER 6" BEDDING

30.0'

NOTES:

1. CONTRACTOR SHALL VERIFY INVERT OF EXISTING SPILLWAY SLAB PRIOR TO

DEMOLITION. IF SLAB IS VERIFIED AT MINIMUM BREACH DEPTH,

CONTRACTOR CAN LEAVE SLAB IN PLACE.

2. RIPRAP AND BEDDING EXTEND FROM CHANNEL BOTTOM TO DAM CREST.

3. INSTALL ADDITIONAL RIPRAP TO TIE INTO SLOPES.

4. FISH AND WILDLIFE SERVICE TO INSTALL BOULDERS AT THE RIGHT

ABUTMENT OF THE BREACH.

1.5

EL. 1282.5

PRECONSTRUCTION

GROUND SURFACE

24" CLASS A

GRADATION RIPRAP

OVER 6" BEDDING

LIMITS OF

DISTURBANCE

270.0'

120.0'

TEMPORARY CONTROL POINT TABLE

Point #

CP1

CP2

CP3

CP4

Northing

713513.92

713491.33

713461.68

713484.26

Easting

2414492.78

2414641.07

2414636.56

2414488.27

Elevation

1282.50

1282.50

1282.50

1282.50

EXISTING STRUCTURE

TO BE REMOVE

EL. 1282.5

EL. 1285.2

EL. 1285.2

DESIGNED DRAWN CHECKED DATE DRAWING NO. SHEET

OF

SUB-SHEETSAND LAKE NATIONAL

HOUGHTON DAM REMOVAL

JJT SAA SLJ 5/14/21 6R-SD-168-19-018 5 5

EAST AND WEST ACCESS GATE C3

25'-4"

6"

C3

3'-0"

3'-0"

18" MIN.

BACKFILL CONCRETE

(NOTE 2)

6" DIA. CONCRETE

FILLED BOLLARD

1 38" DIA. STEEL PIPE

(NOTE 1)

2 3 8" DIA. STEEL PIPE

(NOTE 1)

GATE HINGE

(TYP. 4)

TYPICAL LOCKING

SYSTEM

12'-0"

2'-6"

ELEVATION

DOUBLE SWING GATE

C1 A

TYPICAL DETAIL

BOLLARD

C3

NOTES:

1. GATE SHALL BE A TRI-TUBULAR GATE CONSISTING OF ALL GALVANIZED

STEEL.

2. CONCRETE SHALL BE MINIMUM COMPRESSIVE STRENGTH OF 3,000 PSI.

3. GATES TO BE INSTALLED AT BOTH EAST AND WEST END OF THE PROJECT

AT THE DIRECTION OF THE REFUGE.

0 1 2 3 4 Scale in Feet

0 4 8 16 24 Scale in Inches

Appendix D

Photos

Houghton Dam Removal – Site Visit Photo Documentation July 2020

1. View of the existing service spillway and Houghton Dam looking left from the right abutment.

2. View looking downstream from the right abutment at the deteriorated spillway structure.

3. View looking right from the left side of the spillway structure. Note water level was measured to be 29-inches below crest.

4. View looking right from the spillway structure at where breach will start and possible turnout and fishing pier.

5. View looking left across the dam. Note dike going east of breach will not include any construction modifications.

6. View of the highway bridge downstream of Columbia Dam. Note the water level is approximately 1,400 cfs.

Appendix E

Riprap Calculations

Subject Made by CBM Job No. 1772.34.01

Checked JJT Date 3/22/2021

Approved JJT

Objective:

Method:

Calculations:

The following hydrologic results were obtained from the frequency analysis

Table 1 – Flood Frequency Hydrologic Results

Storm

ARI

(yr.)

The resulting inflow values from Table 1 were used in the HEC-RAS model to determine the following:

Table 2 – HEC-RAS Hydraulic Results

Storm

ARI Channel Velocity Depth

(yr.) (ft/s) (ft)

5 5.83 4.8

10 6.38 6.1

25 6.78 6.6 100 7.68 8.9

FHWA riprap sizing method using the following equation:

d50 ((0.692) / (Gs - 1)) (V / 2g) where:

d50 = mean rock diameter (ft);

Gs = specific gravity of riprap (2.5 Gs 2.7);

V = mean channel velocity (ft/s); and g = gravitational acceleration (g = 32.1740 ft/s

Table 3 – Riprap Sizing for Breach

Breach width V S Gs g d50 d50

(ft) (ft/s) (ft/ft) (ft/s ) (ft) (in)

5 5.83 0.0050 2.65 32.1740 0.22 2.66

10 6.38 0.0050 2.65 32.1740 0.27 3.18

25 6.78 0.0050 2.65 32.1740 0.30 3.60

100 7.68 0.0050 2.65 32.1740 0.38 4.61

Conclusions / Results:

References:

1)

2) South Dakota Department of Transportation (SDDOT, 2015). Standard Specifications for Roads and Bridges . 2015.

7635.0 13000.0

Peak Storm Values

Inflow

(ft /s)

3181.0

4883.0

Based on the riprap sizing results in Table 3, a d50 of 6 inches is required. Wheeler selected a Class A Riprap Gradation per South Dakota Department of

Transportation Standard Specifications with 50 percent passing a rock size at 0.95 feet. This riprap class was selected because it should be more accessible for construction purposes and considered conservative or larger than required.

U.S. Department of Transportation, Federal Highway Administration (FHWA, 2006). Hydraulic Design of Energy Dissipators for

Culverts and Channels, Hydraulic Engineering Circular No. 14, Third Edition. Publication No. FHWA-NHI-06-086. July 2006.

Input Parameters FHWA Results

Peak Storm Values

Houghton Dam Removal

The method for sizing riprap is from "Hydraulic Design of Energy Dissipators for Culverts and Channels, Hydraulic Engineering Circular No. 14, Third Edition, Section 10.3" (FHWA, 2006).

Inflow and outflow discharges for Houghton Dam were calculated doing a frequency analysis as described in this report. A table below shows the results of the analysis.

Hydraulic parameters (flow depth, velocity, bed slope, etc.) associated with the inflow design storms summarized below was obtained from the HEC-RAS hydraulic model. The model is located at: R:\1700\1772\1772.34.01_Houghton_Dam_TitleII\8_Analysis\HECRAS

Size riprap for the proposed breach of Houghton Dam. Riprap sizing was based on the frequency analysis results which include the 2 year though the 100-year design storm.

March 2021 \\ww-rs1\CLIENT\1700\1772\1772.34.01_Houghton_Dam_TitleII\8_Analysis\RiprapSizing\Stilling_Basin_Riprap_Sizing

W.W. Wheeler and Associates, Inc. 1772.34.01