case studies: foundations over artesian

1

CASE STUDIES: FOUNDATIONS OVER ARTESIAN

GROUNDWATER FORMATIONS

Christopher R. Byrum, Ph.D., P.E.Soil & Materials Engineers IncSoil & Materials Engineers, Inc.Plymouth, MI Office

2

Formation of Artesian Conditions

From Dorr & Eschman “Geology of Michigan”

From Michael S. GaberMDEQ “Flowing WellHandbook”

3

GENERAL:

*3% of MI Wells

First Reports 1100A.D.In Belgium/Netherlands

Key to Winter SurvivalBefore Electricity

Inspired Well DrillingTechnology

Extreme-Alvin, Texas120 feet of Head!

Rose City:270 gpm 2” dia

Cedar, MI:450 gpm, 4” dia.69 feet above groundg

4

Naubinway:Highest in MI !84 feet above groundg

Some Other Well Known Spots.

CASE 1Huron River:20-30 feet aboveRiver Level

5

CASE 2Tobacco River:≈ 10 feet aboveRiver Level

BRIDGE HOT SPOTS

*Lakebed/TillInterface ZoneWith GlacialSpillway Channels.

*Glacial SpillwaysInland.

BLUES = Ancient Glacial LakebedGREENS/BROWNS = Glacial Moraine Ridges

Off-WHITE = Glacial Spillway Channels

SITE 1

6

Old Dixboro Road over Huron River

Ambulances were often stuck waiting for the Trains

Existing Bridge

7

Relocated Roadway

Existing Bridge

New Bridge:Spans River, RR andSewage Plant Drive

8

N

HURON RIVER

HURON RIVER

9

Artesian Zone

HURON RIVER

Fort Wayne

Initial Glacial Lakebed Clay Deposition

From Dorr & Eschman “Geology of Michigan”

Fort WayneDefiance

Glacial Re-Advance, Over-Consolidates initial Lakebed Clay New Lakebed Clay Deposition

Upper Clays SPT = 10-30 bpfLower Clays SPT = 50-100+ bpf

From Dorr & Eschman “Geology of Michigan”

10

Fort WayneDefiance

Inter-Lobate Zone

Head Below Lakebed Clays

Huron Channel Cuts Through Lakebed at Some Places

From Dorr & Eschman “Geology of Michigan”

Year 1904Artesian Water Map

A850

D700

C750

B800

SITE

River Water Elev. ≈735 Feet (-25)

Artesian Elev. ≈760 Feet

Bridge Footing Elev. ≈720 Feet (-40)

Green = Artesian Pressure Head Contours

Ann Arbor

YpsilantiSITE 720 Feet ( 40)

Top of Clay Cover. ≈708 Feet (-52)

Clay Cover Thickness10-20 feet

Natural Barrier GradientΔH/ ΔL = 25/10 = 2.5> 1.0 unstable

p

Saline

Year 1904Artesian Water Map

A850

D700

C750

B800

SITE

River Water Elev. ≈735 Feet (-25)

Artesian Elev. ≈760 Feet

Bridge Footing Elev. ≈720 Feet (-40)

Green = Artesian Pressure Head Contours

SITE 720 Feet ( 40)

Top of Clay Cover. ≈708 Feet (-52)

Clay Cover Thickness10-20 feet

Natural Barrier GradientΔH/ ΔL = 25/10 = 2.5> 1.0 unstable

Implies Head-Loss Through theCover Soils in the Spillway

11

Evaluating Chance of Artesian Being Present

SITE

4 Miles

Ice Margin Lateral Spillway

SITE

Primary Interlobate Spillway

950 920

850

830

800

880

950 850900

4 Miles

SITE=730

748730

870

770

750

850770

770

790

880

12

General Dixboro Artesian ConditionsElev 900-950

Ground Elev 730Artesian Elev 760

From Dorr & Eschman “Geology of Michigan”

4 Miles

Probable Artesian Was Identified BeforeGeotechnical Evaluation, SO:

Artesian Drilling Protocol Was Used:

1. Do not poke a hole into the artesian within the proposed cofferdam limitsproposed cofferdam limits.

2. Do not poke a hole into the artesian where you cant seal it (Barge Test Hole performed in the middle of a River).

Artesian Drilling Protocol Was Used:

3. Use Special Drill Rigs with ability to grout and drive casing (Water Well Rigs).

4 Do poke a few holes into the Artesian in select areas4. Do poke a few holes into the Artesian in select areas that can be sealed and measure:

A. the static head and flow rate.B. the cover soil type/thickness.C. the artesian soil type and thickness.D. depth to hard bottom below the artesian soil.

13

Dixboro- We Never Found The BottomTwo deep holes were attempted (each side of the river)

but terminated within the artesian sands because:

1. 14-18 hours per test hole (Tough Holes).

2. Artesian formation was very dense to extremely dense sands with low production ratessands with low production rates .

3. Erosion was getting bad after drilling almost 50 feet into the artesian formation.

4. Drill Crew Chief Said.. Seal it “Now or Never”.

SOIL BORING LOCATION DIAGRAM

N

N

14

Beach Sands

Erosion Wash

Peat Marsh

Channel AlluviumElev. 820 ft

Existing River

Natural ground line

Huron River Valley Section Along New Roadway

Silty Clay Cover

Sand with High Artesian Pressure

Elev. 690 ft

Clay Cover is Thin Below RiverGlacial Spillway Scour Limit

Sta. 0+240 mSta. 1+060 m

Artesian conditions were close to the Ground Surface and intense at this site

Flow out of SB5 Casing

Flow out of SB5 Casing created the “SME Creek”

Artesian Flow and Casing at SB5

15

SB5

Engineered Scour Countermeasure

Artesian water has high mineral content.

•SB5 did not flow during or just after completion of drillingp g

•It took a few months for piping instability to develop through the bore hole

16

Piping Instability- Hydraulic Gradient, i =

Sand- Atmospheric

LHΔΔ

HΔG.W.T.

Artesian Pressure Head

Piezometers

Clayey Cover

Artesian Sand

LΔ

LH

ΔΔ

= in-situ barrier gradient

Piping Instability- Hydraulic Gradient, i =

Sand- Atmospheric

LHΔΔ

HΔG.W.T.

Artesian Pressure Head

Partial Penetration Holes

Clayey Cover

Artesian Sand

1LΔ2LΔ

3LΔ4LΔ

1LH

ΔΔ

4LH

ΔΔ

= in-situ = approaching ∞

IF:

Hydraulic Gradient, i = > Piping Threshold

THEN:

LHΔΔ

Piping will eventually Blow Through !!!!

Who knows how long it will take !!!

17

Erosion Equilibrium – Hydraulic Shear Stress “Particle Plucking”

How Does Piping Initiate ? Something Like This.

LΔ

Time

3LΔ4LΔ

2LΔ

1LΔ

Piping Instability- Hydraulic Gradient, i =

Sand- Atmospheric

LHΔΔ

HΔG.W.T.

Artesian Pressure Head

Partial Penetration Holes

Clayey Cover

Artesian Sand

1LΔ2LΔ

3LΔ4LΔ

1LH

ΔΔ

4LH

ΔΔ

= in-situ = approaching ∞

CRITICAL PENETRATION?

Erosion Equilibrium – Hydraulic Shear Stress “Plucking”

How Does Piping Initiate ? Something Like This.

LΔ

“Blow-Holes” Become filled in with coarser sands under hydrostatic uplift = QUICK SAND

Time

3LΔ4LΔ

2LΔ

1LΔ

18

30 to 40 ft

From Michael S. GaberMDEQ “Flowing WellHandbook”

10-ft

19

Hammer = Very Simple Single Piston Diesel Engine

Exhaust

Driving a Crane onto a Floating Barge

Driving a Crane onto a Floating Barge

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Pier 4 Cofferdam

Pier 3 Cofferdam

Pier 3 Cofferdam

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Pier 3 Cofferdam

Pier 2 Cofferdam

Jet Grouting Equipment and Platform (crane mats on I-beams) resting on the Pier 2 Cofferdam

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Jet-Grouting Equipment

Jet-Grouting Equipment

Jet-Grouting Equipment

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Jet-Grouting Equipment

Jet-Grouting Equipment

Jet-Grouting Equipment

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Jet-Grouting 100% Overlapping Pattern/Sequence

By Hayward Baker, Inc.

Jet-Grouting Cross Section

Settlement

By Hayward Baker, Inc.

Reduction and Cofferdam Seal “All-In-One”

Pier 1- Jet Grout Soil-Cement Testing Summary

0

200400

600800

1000

1200

1400

16001800

2000

0 7 14 21 28 35Sample Age days

Unc

onfin

ed C

ompr

essi

ve S

tren

gth,

psi

ws-Col.3-5.5'ws-Col.3-0.5'ws-Col.19-5.0ws-Col.19-4.0ws-Col.8-4.0ws-Col.8-3.0ws-Col.6-6.0ws-Col.6-5.0ws-Col.3-2.5ws-Col.3-3.5ws-Col.4-2.5ws-Col.4-3.5ws-Col.5-2.0ws-Col.10-3.5ws-Col.10-1.5ws-Col.9-3.0ws-Col.9-2.0C1-Run2-Part3C2-Run1-Part1C2-Run1-Part3C3-Run1-Part1aC3-Run1-Part1bC3-Run2-Part2C3-Run2-Part3

updated 12/27/2004Sample Age, days updated 12/27/2004

Pier 1 Grout Strengths

0500

1000150020002500300035004000

11/17 11/18 11/19 11/20 11/21 11/22 11/23

Construction Date

Com

pres

sive

Str

engt

h,

psi

71428

Test Age, days4230

25

Median Soil Cement and Grout Strength Values

10001500200025003000350040004500

Unc

onfin

ed C

omp.

psi

P1 S.C.P1 GroutP2 S.C.P2 GroutP3 S.C.P3 Grout

0500

0 7 14 21 28

Wet Sample Age, days

U Design Minimum Strength = 300 psi

Hayward-Baker Staff Recover a Jet-Grouted Soil Cement Core

Jet-Grouted Soil-Cement Core

26

Column Interface is Well Bonded

Stiff-Hard Clay and Jet Grouting Don’t Mix Well

Pier 4 Cofferdam

27

Tremie-Poured Concrete Mud-Mat ?

1. Placed Underwater like a Tremie Seal.

2. However, too thin to meet Tremie Design Criteria for Required Bond + Weight to manage River head.

Pier 4 Cofferdam

Observed Artesian FlowDuring Sheet Removal

Short Sheet Removed“Vent Sheet?”

Pier 4 Cofferdam

White/Gray Flour Color is Eroding Gray Lakebed Clays !!

Cofferdam Contractor new something was wrong when water inside didn’t “clear up”

28

While Attempting First Dewatering of Cofferdam--

Pier 4 Cofferdam Dewatered to top-of-tremie

Uncontrollable 300-500 GPM flow blew under the mud mat and out the far side causing obvious major erosion beneath the footing mud mat.

29

Cofferdam SheetsAnd Mud Mat

Old River Bank Sea-Wall

Cofferdam Sheets

Old River Bank Sea-WallInitial Flow

Cofferdam Sheets

30

Old River Bank Sea-WallInitial Flow

Cofferdam Sheets

Major Erosion Beneath One of the Two Pier Columns.

Sheet-Pile Cofferdam

normal river level

Sea Wall SheetingArtesian head

Before Dewatering Artesian Sands

Clay Cover

Original Flow Hole Up Sea Wall

Sheet-Pile Cofferdam

normal river level

Artesian head

After Dewatering Artesian Sands

Clay Cover

Finds New “Path of Least Resistance”After dewatering cofferdam

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Do we need an Artesian Dewatering Well?

OR

Can we install the foundation without Lowering the Artesian Pressure Head?

Artesian Dewatering Well-REQUIRED

Pressure Grouting of Mud Mat-REQUIRED

**Too much flow to pour concrete, and obvious erosion under mud mat going on

Artesian Dewatering Well

32

800 gpm Artesian Dewatering Well

800 gpm Artesian Dewatering Well

Artesian worm-hole outlet needed special attention

33

Lots of Silty Clayey Erosion Mud Flowed out on top of Mud Mat

218

220

222

224

226

Dow

n El

ev, m

Draw Down Estimates - NAVFAC

212

214

216

218

0 5 10 15 20

Distance from Well, m

Dra

w D

34

218

220

222

224

226

Dow

n El

ev, m

B.O.F.T.O.F.

Draw Down Estimates - NAVFAC

212

214

216

218

0 5 10 15 20

Distance from Well, m

Dra

w D

0 228.2575 226.8

Draw Down Elev = -0.0193(Flow Rate) + 228.25

218220222224226228

atio

n, m

eter

s

Flow Rate vs. Draw Down Estimates - NAVFAC

212214216218

0 200 400 600 800Flow Rate, gpm

Ele

va

To get 213 m use min. 800 gpm well

Dixboro Rd over Huron RiverArtesian Well Draw-Down

216

218

220

222

224

226

228

Hea

d El

ev. m

212

214

216

0-Jan 1-Jan 2-Jan 3-Jan 4-Jan 5-Jan 6-Jan 7-Jan 8-Jan

Date

Actual Well Reached 213 meters at about 6 days at constant flow averaging 800- 1,000 gpmThis is about 8,000,000 Gallons

35

Pier 4 Footing Pour

Pier 4 Footing Pour

800 gpm Artesian Dewatering WellFlows reduces to about 100-200 gpm when fully developed

Pier 4 Footing Pour

36

Pier 4 Footing Pour

Pier 4 Footing Pour

Pier 4 Footing Pour

37

Pier 4 Footing Pour

Pier 4 Footing Pour

Pier 4 Footing Pour

38

Pier 4 Footing Pour

Pier 4 Footing Pour

Pier 4 Footing Pour

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Grouting of Artesian Erosion Damage to Pier 4 Footing

Grouting of Artesian Erosion Damage to Pier 4 Footing

Grouting of Artesian Erosion Damage to Pier 4 Footing

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Grouting of Artesian Erosion Damage to Pier 4 Footing

Grouting of Artesian Erosion Damage to Pier 4 Footing

Grouting of Artesian Erosion Damage to Pier 4 Footing

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Grouting of Artesian Erosion Damage to Pier 4 Footing

Grouting of Artesian Erosion Damage to Pier 4 Footing

Grout Volume Pumped was Roughly Equal to a 1-ft diameter Tube, 60 Feet Long.

This matched the Eye-Ball Reality Check Factor

Pressure Gage Broke, So we Grouted until we “Heard Cofferdam Walls/Welds Make Noises”Heard Cofferdam Walls/Welds Make Noises

This is Not The Best Way to Control Grouting.

42

Pier 4 Settlement

-20

-15

-10

-5

0

5

ttlem

ent,

mm Beams

Deck Steel/Forms

Concrete Deck

Pier Weight2 mm

15 mm12 mm

Settlement Monitoring Required !!

-35

-30

-25

3/9 3/29 4/18 5/8 5/28 6/17 7/7 7/27 8/16 9/5

Date

Set

East

West

Avg.

Concrete Deck

Concrete Barrier and Initial Live LoadEst.

24 mm27 mm

Pier 4 Settlement

-20

-15

-10

-5

0

5

ttlem

ent,

mm Beams

Deck Steel/Forms

Concrete Deck

Pier Weight2 mm

15 mm12 mm

Settlement Monitoring Required !!

-35

-30

-25

3/9 3/29 4/18 5/8 5/28 6/17 7/7 7/27 8/16 9/5

Date

Set

East

West

Avg.

Concrete Deck

Concrete Barrier and Initial Live LoadEst.

24 mm27 mm

Allowable Footing Pressure based on 1” (25.4 mm)predicted settlement

Pier 4 Settlement

-20

-15

-10

-5

0

5

ttlem

ent,

mm Beams

Deck Steel/Forms

Concrete Deck

Pier Weight2 mm

15 mm12 mm

Settlement Monitoring Required !!

-35

-30

-25

3/9 3/29 4/18 5/8 5/28 6/17 7/7 7/27 8/16 9/5

Date

Set

East

West

Avg.

Concrete Deck

Concrete Barrier and Initial Live LoadEst.

24 mm27 mm

Differential Settlement (left vs. right) = 5-6 mmBeing greater on the undercut/weak clay side

43

44

45

Permanent Artesian Vent

Permanent Artesian Vent

Completed New Dixboro Road Bridge

46

Completed New Dixboro Road Bridge

Completed New Dixboro Road Bridge

Completed New Dixboro Road Bridge

47

ARTESIAN FLOW CASE STUDY: Lang Road Bridge over theMiddle Branch Tobacco River

Christopher R. Byrum, Ph.D., P.E.Soil & Materials Engineers IncSoil & Materials Engineers, Inc.Plymouth, MI Office

SITE

SITE

48

SITE

SITE

SITE

49

SITE

GLACIAL LAKEBED LIMITS

SITE

SITE

50

DIXBOROLANG

Head Below Lakebed Clays

Huron Channel Cuts Almost ThroughAnd Probably Does Cut Through at Some Places

From Dorr & Eschman “Geology of Michigan”

SITE (low res. image)

51

Artesian Drilling Protocol was used! WHY?

Existing Artesian Pond located about 150 feet from bridge, with water at about 5-10 feet above River, and pipe sticking out of the ground with flowing artesian water.

Aerial Photos showing lots of Houses with Ponds

This caused me to check MDEQ Well Logs near the bridge–All were flowing wells, encountering the artesian flows.

Artesian Drilling Protocol was used! WHY?

RESULTS- Clay was too hard to drill through so we hit auger refusal at less than 30 feet deep, before encountering any artesian layers.

We didn’t know how deep it was but we new it was there.

Footing Design Recommendations

1. Use spread footings on hard clays, set as high as possible. Do not drive or pre bore deep piling down towards the Artesian. (Standard Convention would be Pre-Bored Piling)

2. Use permanent sheeting cofferdams with toe as high as practical, and tremie poured seals. (Standard Convention would be Mud Mat for this type of soil, with no toe limits)

3. If scour is deep, set footings higher and use permanent sheeting special designs to deal with scour design depth.

52

First Unusual Signs at the Site

TEST HOLES

Cofferdam Sheets in this Area Drove Deep with little Resistance

About 2 Days after Dewatering, Artesian Blew Through Here.

53

EROSION VOID

54

Grouting Results

1. Grout take was large and grout did appear on outside of cofferdam sheeting.

2. Grout stayed in place in all ports accept the port closest to the flow SOURCE HOLE.

3. Decided to create a permanent vent over SOURCE HOLE, out through rip rap. Design a……….

PERMANENT PREFERRED FLOW LOCATION

55

For the West Side, Artesian Blew Through Here.

Grouting NOT Required Here- Middle of Ftng Likely will “bridge”

Grouting Required Here- Edge of Ftng/Wing Wall Could Separate

56

Possible Cracks/Fissures Through Lakebed Clay

Michigan’s State Fossil:MASTADONPost-GlacialFurry Beast

M E I d zd x

=2

2