Redridge Dam Presentation

STAN VITTON & THE FALL 2007REDRIDGE DAM SENIOR DESIGN

MICHIGAN TECHNOLOGICAL UNIVERSITY

Analysis of the Redridge Dam

Special Thanks

Stanton Township BoardMr. Leonard H. Lamb Jr., P.E., Motor Castings CompanyAPL - Metallurgy & Environmental Consulting LabsMichigan Tech FacilitiesMr. Louie Garnell - WeldingDr. Nels Christopherson - AccessMs. Jen Heglund – Hydrology AnalysisDr. Terry Reynolds Social Sciences Dept. MTURedridge Study Group

Redridge Dam Presentation Outline

Study ObjectivesBackgroundTrestle Access Barricade Analysis

Stream Flow Analysis Structural Analysis

ConclusionsRecommendationsQuestions?

Objectives

Create a timeline of events which occurred at the siteDetermine the original location of the Salmon-Trout

River and its hydrologic flow levelsEvaluate structural stability of the damsProvide technical advise for use by the Stanton Township

Study GroupHelp provide information to Stanton Township to help

manage risks to township and its residentsProvide recommendations for future work

Location

Location

Lake Superior Elevation 600 feet

The Redridge Dam and Beacon Hill/Freda Road

The Redridge Dam

Timber Crib Dam

Steel Dam

Current Road Crossing

Old Road Crossing

Baltic Stamp Mill

Geology

Geology – Freda Sandstone

Freda Sandstone Precambrian – 1 billion Reddish brown sandstone

and siltstones, well bedded and consolidated

2,500 feet thick



Keweenaw Currents

Lake Superior Current

Stamp Sand Migration

History – Timber Crib Dam

Timber Crib Dam Constructed in 1894 Additional construction 1899 Submerged in 1902 to 1921 1921 till dam lowered?

History - Steel Dam

Steel Dam Construction (1900-1901) Completed Nov 1, 1901 Started filling Nov. 15, 1901 Completely filled Jan. 1, 1902 Over topped in 1927, 1941 and

1979

History – Steel Dam

Spillways

CompletedUnder Construction

Location

Emergency Spillway

Timeline

1884 Stamp Mill & Dam on the Salmon Trout River completed

May 1899 Construction of Steel Dam Started Nov 1 Construction Completed Nov. 15 Gates Closed Jan. 1 1900 Steel Dam Filled

1912 Atlantic Mill Closed1921 Baltic Mill Closed1927 Dam Overtopped in Spring Runoff1941 Dam Overtopped due to Beaver Dam Break

Timeline

Nov. 20, 1953 Dam Drained due to Constrcution of a Tunnel Under Road to Freda

1979 Dam Overtopped1979 Copper Range Cut Four Holes in Steel Dam1986 ASCE Designated the Redridge Dam a Historic Civil

Engineering Landmark1992 Stanton Township Took Ownership of the Dam2004 The Top 12 feet of the Timber Wood Dam Removed

The Trestle

Trestle Access Barricade

Both barricades that prevented access to trestle needed repair

Barricade design repair and reconstruction

4” Gaps or smaller (Chap. 10 International Building Code 2006)

No horizontal bracing to deter climbing

Used steel angle iron and rebar: 130 feet of angle iron 290 feet of rebar

Barbwire placed around ends & top to discourage climbing around barricade

Trestle Access Barricade

Stream Analysis

10/25/2007

Bathymetric Map

River Channel Location

Salmon Trout River Location Under Steel Dam

Salmon Trout River Location Under Steel Dam

Salmon Trout River noted at bottom of picture

Pipes located to the west side of dam

Analysis – Stream Flow

Hydrology Base flow - 50cubic feet per

second Area 42.8 mi2

CN – 58 Lag time 26.7 hours Elevation-storage-outflow

relationship Spring Snow Melt

Salmon-Trout River Watershed


Design Storm Event 100 year storm 12, 24, 48, 96 hours Reservoir elev. 652 ft+/-at a

max runoff discharge of 1246 cfs

Current Spillways

Base FlowSpring Flow


Discharge Holes cut at elev 649-652 3 Models Q637 = 43 cfs Q692 =450 cfs Q653 = 1700 cfs (with holes) Q692 =6400 cfs (with holes)

Drainage Time (to elev 650) Elev 664 – 6.6 hours

12’ +/- of Snowmelt Runoff

692

652

637

Structural Stability

Timber Crib Dam

Steel Dam – Gravity Dam

Material Life

Steel

Concrete

Timber

Analysis – Steel

Analysis – Steel

Analysis – Steel

Steel Analysis Chemical Analysis:

The sample is approximately 1006 or 1010 plain carbon structural steel.

Tensile Test: Tensile Strength = 71,700 psi Yield Strength = 54,500 psi % Elongation = 22%

Birnell Hardness (10 mm ball @ 3000kg): 126 BHN

The Electron Energy Dispersive X-Ray Spectrometry (EDS) indicated a non-metallic film or coating on the surface.

Microstructural analysis: Material appears to be ferritic / pearlitic

steel

Analysis – Structural

Slag stringer

Analysis – Steel Corrosion

Analysis – Steel Corrosion Acceleration

Analysis – Steel Corrosion Acceleration

Analysis – Concrete

Concrete Deterioration Caused by water flowing

over foundation through holes cut in steel dam

Estimate of Deterioration Rate Approximately 43 yd3

currently deteriorated Rate is 1.6 yd3 per year

100 year estimation is 202 yd3 of deteriorate


Concrete Analysis

Main weight (gravity dam) of the Redridge Dam comes from the concrete

There are two types of concrete; a capping concrete and a primary base concrete


Capping Concrete Approx. 4 – 5 in thick Encases the entire

foundation of Dam Protects the primary

concrete Low permeability, very

dense


Primary Concrete Approx. 12 - 15% voids Design - 145 pcf - pounds/foot3

Test results 1901 165 pcf – Measured on site 1800 psi – 26 Day

Actual – 134 pcf ASTM (C -642) Large Aggregates

Mine Rock Small amounts of Copper Large Voids

Analysis – Steel Dam Stability

Stability of Steel Dam Gravity Dam - weight of

structure plus downward component of water resist sliding

Factor of Safety (FS) when fully loaded with water at 692 feet Currently FS ~1.40 for 134

pcf concrete FS ~1.35 after 100 yrs of

concrete deterioration

Steel Dam Stability

Factor of Safety current condition significantly higher

Steel corrosion of support members as well as concrete pedestals is a concern if the dam becomes fully loaded

However, we believe that the current loading on the steel support member is very low and is not significant to the stability of the dam

Rehabilitation of both the steel and the concrete is possible

Timber Crib Dam – Structural Stability


The Civil Engineers Pocket Book, John Trautwine. 1886

Timber Crib Rockfill Dam


Timber Crib Dam Elements

Bathymetric Map

1894 Condition

Timber Crib - Date Unknown

1899 Condition

Timber Crib Dam Mid-1960’s

2004 Condition

Timber Crib Post 2004

Steel Dam Conclusions

Our analysis indicates: More than likely the Salmon

Trout River is located in its original location

The stability of the steel dam against sliding even under fully loaded conditions is good

The current emergency spillway appears adequate for a 100 year event

Steel Dam Conclusions

Our analysis indicates: The emergency spillway has

accelerated deterioration of the steel and concrete in the dam

Deterioration of concrete has not significantly affected the factor of safety of the steel dam against sliding

Deterioration of the steel and concrete pedestals is of some concern and should be address sometime in the future

Timber Crib Dam Conclusions

Our analysis indicates: A rock fill dam supports the

timber cribbing and acts as an energy dissipating system

Timber planking was used as a water cutoff wall between rock fill and timber crib

As the wood planks deteriorate over time the timber crib dam will no longer be able to hold back water

Timber Crib Dam Conclusions

Timber crib dam stability The removal of the upper 12

feet of the dam significantly improved its stability and appears to be very stable

Over time, however, the timber cribbing will deteriorate and the rock fill inside the cribbing will come to an equilibrium consistent with the rock’s angle of repose of the rock and water flow conditions

Recommendations

Conduct a more detailed stability analysis of the steel and rock crib dams based on the following issues: Current condition Condition based on

Rate of steel corrosion Rate of concrete deterioration Deterioration of the timber

cribbing and planking

Recommendations

Determine how long the dams can remain stable without intervention

Consider the following two options: Restoration of Salmon Trout

River by removing a section of the concrete base below the steel dam; thus, preserving the historical integrity of the dam

Alternate uses of the dams or portions of the dams in a originally designed condition

Questions?

Documents

Redridge Dam Presentation