Steve Hubbs & Tiffany Caldwell University of Louisville Clogging in Louisville.

Steve Hubbs &Tiffany CaldwellUniversity of Louisville

Clogging in Louisville

This presentation:

• Provide some slope data from US Rivers.

• Present calculations for Specific Capacity and decrease with time at Louisville (clogging).

• Analyze Pump Test data from 1999 and 2004 for indications of Riverbed compression at Louisville.

• Analyze field data for flux and head

• Review calculations of riverbed hydraulic conductivity (K) for 1999 and 2004 at Louisville.

Typical RBF systems in US

• Smaller system capacity (5,000 m3/day)

• Recent tendency for large systems (100,000 m3/day) and larger

• Located very close to streams (30 meters from bank)

• Laterals extend under riverbed

Sites with RBF Systems

• Louisville, 20 MGD (45 MGD planned), Ohio River

• Cincinnati, 30 MGD, Great Miami River

• Somoma, CA. 45 MGD, Russian River

• Lincoln NE, xx MGD, Platte R

• Des Moines, KC,

• Considering: St.Louis, New York, others

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Distance from Mouth (km)

Wat

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urfa

ce E

leva

tion

(m

)

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Distance from Mouth (km)

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urfa

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Missouri River

Mississippi River

Platte River

North Platte River

Ohio River

RBF Sites

RIVERBANK FILTRATIONAn effective technique for public water

supply

– An ancient technology…documented in the Bible!• Exodus 7:24 “…dug around the Nile for water to drink.

Filtered through sandy soil near the river bank, the polluted water would become safe to drink.”

– Modern installations in Germany over 140 years old– Extensive development in US since the 1950s– Recent interest as a treatment technique for

Disinfection By-Product and Pathogen Regulations

Steve Hubbs

You can exclude the biblical quote if you like

Indications of Clogging

• Louisville capacity decreases to 67% of original level over 4 years, hardpan present.

• Cincinnati “hardpan” forms when pumping at high levels under low-stream flow conditions

• Sonoma infiltration beds hard to penetrate and unsaturated below surface.

• Initial capacity of collector wells decrease after several years of operation.

Factors Impacting Yield

• Temperature (River, Aquifer, Well)

• Time (used as a surrogate for plugging)

• Pumping Rate and Driving Head

• Aquifer Characteristics (at riverbed, through bulk of aquifer, near wellscreen)

• Water Quality

Factors Restoring Yield

• Riverbed shear stress and scouring

• Biological “Grazing” (Rhine River)

• Mechanical Intervention (Llobregat River)

Sustainable Yield

• The long-range sustainable yield is a balance between all yield-limiting factors and all yield-restoring factors

• The question is: How do we measure and predict all of these factors?

• Focus of this part of the presentation: looking at the composite of plugging factors, and the impact of shear stress on sustainable yield.

Predicting Sustainable Yield

• Use a combined stochastic/deterministic approach.

• Specific Capacity = Flow/(river head - well head)

• Cs = a*(river temp) + b*(well temp) + c*(time)

ModelCs = intercept + (a) River T + (b) Well Temp + Plugging

Plugging is a function of Time (Time used as a dummy variable)

Linear Time

Log time

NOTE: This model is “forgiving” for inaccuracies in calculatingSpecific Capacity…in other words, if the assumption regarding Specific capacity being constant with Well Flow Q is WRONG, the regression for Temperature and Plugging will compensate for thiswrong assumption.

Raw Data (weekly averages)

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100.0

0 20 40 60 80 100 120 140 160 180 200

Week

Te

mp

F, L

ev

el F

t, Q

MG

D

Well Level

Well Flow

Well Temp

River Temp

River Level

Raw Data for Regression Model

30.0

40.0

50.0

60.0

70.0

80.0

90.0

1 21 41 61 81 101 121 141 161 181 201Week

Tem

pera

ture

: F

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1.0

Spe

cific

Cap

acity

: MG

D/f

eet

of d

rivin

g he

ad

River Temperature

WellTemp

Specific Capacity

Model with Temperature only

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0.000

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0.500

0 20 40 60 80 100 120 140 160 180 200

Period (weeks)

Sp

ecif

ic C

apac

ity

(no

rmal

ize

d a

bo

ut

mea

n)

Regression: Cs = (0.491-0.48) + .0044 Well Temp + .0036 River Temp

R = .62F = 52

Actual

Predicted

Figure 5: Regression vs Actual, Linear Time

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Time, weeks

Sp

ec

ific

Ca

pa

cit

y (

no

rma

lize

d t

o m

ea

n o

f 0

.49

1 M

GD

/ft)

Cs = (0.491-0.41) + .0071 Well Temp + .0013 River Temp + -.0015 Linear Time

R = .91F = 266

Actual

Predicted

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0 20 40 60 80 100 120 140 160 180 200Period (week)

Spe

cific

Cap

acity

(no

rmal

ized

to

mea

n of

0.4

91 M

GD

/ft)

Cs (MGD/ft) = (0.491-.013) + .0045 (Well Temp. F) + .0018 (River Temp F) - .095 (Ln (Time week))

R = 0.96F = 583

Specific Capacity immediate followingflood event is greater than predicted

Period of flooding

Actual Data

Predicted Values

Regression Model, “cleaned data”

Projection of Model-20 years

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0 200 400 600 800 1000 1200

Time (Weeks)

Spe

cific

Cap

acity

(no

mal

ized

to

mea

n of

0.4

91 M

GD

/ft)

Point of Projection

Extrapolation with Jump

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0.000

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Week

Sp

ec

ific

Ca

pa

cit

y (

no

rma

l to

me

an

of

0.4

91

MG

D/f

t))

Projected

jumpjump jump

"Jump" is an added .0022 MGD/ft every 4 years to model

Modeled

September 9, 2004

Impact of 4 month layoff, 2004

• Pump failures resulted in long downtime

• Pumps off during high flow events of spring 2004

• Pumps restarted July 28, 2004

• Pump test of 1999 repeated

Projection with Jumps-capacity in MGD

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Time (weeks-20 years)

Max

Well

Capaci

ty-M

GD

Jumps

ExtrapolationHistory

August 2004 (predicted)

Specific Capacity: Measured: 0.545 MGD/ftPredicted: 0.36 MGD/ft

measured

Specific Yield Calculations

• Adjusting for temperature, the calculated specific capacity for 2004 is 0.645 MGD/ft at week 4 of pump test.

• A similar calculation for specific yield was 0.848 for 1999 after week 4 of pumping.

• Current capacity approximately 76% of original after layoff and scouring event.

• Previous measurements indicated that capacity was approximately 67% of original.

Pump Tests at LWC

• 1999 Pump test

• 2004 Pump test

• Direct measures of infiltration

20 MGD Collector Well: Ohio River at Louisville

Silt ClayOhio River

Bedrock

Sand and Gravel

L4

Path 1Path 0 Path 2

50 feet

800 feet

Path nPath i

Figure 6.10 2-Dimensional Water Flow Paths from the River to Laterals

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450

0 200 400 600 800 1000 1200 1400 1600 Distance from the Collector Well (feet)

Elevation (feet above sea level)

River Level = 420 feet

River Bed Surface

Piezometric Surface

Saturated Zone

Unsaturated Zone

Ohio River

Alluival Aquifer Sand and Gravel

Intersection of piezometric surface and Riverbed

Measured 2 feet below riverbed

Figure 6.5 Temperature Profile of Riverbank Filtration during Initial Pumping

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Pumping time (Hours)

Tem

per

atu

re (

Deg

ree

C)

W1 W2 W3

Pump Start Time: 13:20, June 23, 1999Pumping Rate: 20 MGD

River Temperature: 26.5 oC

River WaterReached W2



The aquifer velocity q is measuredat the mid-point of curve at W1 (P39)at 1.08 hours for the 2 foot distance or 2 feet/hour

The measured head loss at P39 was10 feet across the 2 foot vertical distanceyielding a riverbed K value of:K=(2’/10’)(2ft/hour)=0.4 ft/hr (0.12m/hr)

P39

1999

Figure 7.1 Turbidity Results of the Ohio River and the Collector Well

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1

10

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1000

1/1

1/22

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111

/11

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31/

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28

Date (Year 2000 & 2001)

Tu

rbid

ity

(NT

U)

River Collector Well

n=480

Figure 7.2 Turbidity Removal as a Function of Filtration Distance

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Riverbank (Aquifer) Filtration Depth (feet)

Tu

rbid

ity

(NT

U)

Sampling Period: July 1999 - Feburary 2000n=21

W1 W2 W3

L4

River

2004 pump test repeat

Pump Test July 2004-P39

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28

7/22/2004 0:00 7/27/2004 0:00 8/1/2004 0:00 8/6/2004 0:00 8/11/2004 0:00 8/16/2004 0:00 8/21/2004 0:00

Date

Te

mp

era

ture

- d

eg

ree

s c

elc

ius

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420

425

Temperature

Piezometric Surface 0.6 meter below riverbed

Aquifer velocity q calculated at 20.6 oC at 3.3 hours for the .6 meter distance

Riverbed K value calculated at K=(2'/12.5')(2'/3.33hrs)=.096ft/hr = .03m/hr

Head loss across riverbed is measured at 3.8 meters

Start pump test

0.6 meter below surface

Temperature Data-Pump Test Start-up

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0 50 100 150 200 250 300 350 400

Hours from start of test

Tem

per

atu

re-d

egre

es C

1999 Pump Test

2004 Pump Test

Temperature measured 3 meters below the riverbed

3 meters below surface

2004 Pump Test Data-Temperature and Piezometric Surface 3 meters below riverbed

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0

5

10

15

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25

30

7/22/04 0:00 7/27/04 0:00 8/1/04 0:00 8/6/04 0:00 8/11/04 0:00 8/16/04 0:00Date

Tem

per

atu

re d

egre

es C

390

395

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405

410

415

420

425

Pie

zom

etri

c el

evat

ion

Piezometric Water Level

TemperatureRiver Level - 420 feet

Riverbed elevation ~ 403 feet

Piezometric surface crosses riverbed

Temperature Data-Pump Test Start-up

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5

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0 10 20 30 40 50 60

Hours from start of test

Tem

per

atu

re-d

egre

es C

1999 P37 (3.0m)

2004 P37 (3.0m)

2004 P39 (.6m)

What’s going on?

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Ohio River

Lateral L-4

Geokon Probe P37

t=20 min

t=2 days

BEDROCK

Sand and Gravel Aquifer

Piezometric surface

Geokon Probe P39

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450

0 200 400 600 800 1000 1200

Ohio River

Lateral L-4

Geokon Probe P37

t=20 min

Several months

BEDROCK


Compressed Riverbed

Piezometric Surface

Interpretation of 2004 Temp data• Pump test starts with aquifer saturated to 420’.• As head increases, vertical velocity increases and

piezometric surface drops.• After 8 hours, the piezometric surface intersects

and drops below the riverbed. Riverbed conductivity reduces sharply, and the flow path shifts from vertical to horizontal.

• The piezometric surface continues to extend, increasing the distance of flow and bringing in cooler aquifer water. Minimal flow is passing P39.

• The piezometric surface stabilizes, and temperature increases to river temperatures.

330

340

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450

0 200 400 600 800 1000 1200

0

Winter: T = 2oC Summer: t = 28oC

Piezometric Surfaces: Summer 2002 and Winter 2003

14oC

22oC

Direct Measure of Riverbed Flux Rate

• Seepage meter procedure modified for deep river use– Heavy “can” 1 sq. foot surface (0.093 sq meter)– Flexible connection to surface– Stilling well at river surface– Camera to observe riverbed conditions

Problems with flux measurement

• Wind, Waves, and Current are enemies

• Unable to work when river velocity exceeds 1 mph (1.6 km/hour) due to erosion of seal

• Wind/waves make boat and stilling well pitch

• It takes near-perfect conditions to get repeatable data

Seepage meter“can”

Hose to Attach to Bladder

In StillingWell

Stilling Well

330

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0 200 400 600 800 1000 1200

Ohio River

Lateral L-4

Geokon Probe P37

t=20 min

Several months

BEDROCK


Piezometric Surface

No flux Area of high flux measurement

Calculating Riverbed K from direct measurement of infiltration rate

• Approach Velocity measured at .3 to 1 meter/hour• Porosity assumed at 0.2• Aquifer velocity q = (.3/0.2) = 1.5 m/hour• Head loss across riverbed at 0.6 meter depth is 6 meters

• K=(L/hL)(q)= (0.6/6)1.5m/hour = 0.15 m/hr

• Measured range based on approach velocities was 0.15 to 0.45 m/hour

Summary of Measured Riverbed K values

• At identical points (P39, 0.6m depth)– 1999 temperature-derived value = 0.12 m/hr– 2004 temperature-derived value = 0.03 m/hr

• From direct measure of flux across riverbed– Max 2003 flux-derived value = 0.45 m/hr– Typical 2004 flux-derived value = 0.15 m/hr– Max 2004 flux-derived value = 0.38 m/hr

Measuring Riverbed Compression

• 0.33 meter Drift Pin attached to 1 meter rod

• Dropped a distance of 0.58 meters.

• Penetration into riverbed observed by underwater camera.

• Submerged trees are the enemy!

Results of Penetrometer

• Riverbed surface varies considerably.

• Drift pin penetrates up to 0.33 meters in undisturbed areas…typical is 0.15 meters.

• Penetration is less than 0.05 meters in areas of riverbed compression near well.

• Additional measurements needed to define area of riverbed compression.

Ongoing Work at Louisville

• Mapping infiltration rates.

• Mapping riverbed compression area.

• Proceeding with expansion of wellfield from 20 MGD to 60 MGD total capacity (75,000 m3/day to 225,000m3/day)

• Using vertical wells (as opposed to horizontal collectors)

Discussion

• Any other observations regarding compression of riverbed?

• Do the values of riverbed “K” look right?• Any other theories about riverbeds under

unsaturated conditions?• Guidance regarding design and operation of

RBF systems with regards to unsaturated conditions under the riverbed?

Figure 5.1 Particle Size Distribution of Aquifer Materials at Different Depths(at Collector Well)

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100

0 0.5 1 1.5 2 2.5 3 3.5 4

Particle Size (mm)

Cu

mu

lati

ve P

erce

nt

Ret

ain

ed

85-90 ft 80-85 ft 75-80 ft 70-75 ft 65-70 ft 60-65 ft 55-60 ft

Fine Sand Course Sand Very Fine Gravel Fine Gravel

Laterals located near the bottom of this layer

PrecipitationPrecipitation

Direct Runoff

Direct Runoff

Direct Runoff

Soil and clay

Water Table

Sand and GravelShale

Shale

Shale

Shale

Limestone

Zone of solutionaldevelopment

Zone of poorcirculation

Eva

pora

tion

Tra

nspi

ratio

n

Ohi

o R

iver

Velocity profiles from Doppler data (USGS)

OHIO RIVER DATA AT BEPWTPvelocity depth shear

velshr strs fric

slopefeet/sec feet feet/sec Newtons per

10005.34 37.545.53 35.9 -1.70 -8.35 -0.0745.50 34.26 0.26 0.19 0.0025.13 32.62 3.02 26.26 0.2345.57 30.98 -3.41 -33.58 -0.2995.31 29.34 1.91 10.55 0.0945.25 27.7 0.42 0.50 0.0044.91 26.06 2.23 14.32 0.1284.96 24.42 -0.31 -0.27 -0.0024.82 22.78 0.81 1.87 0.0174.67 21.14 0.80 1.86 0.0174.31 19.5 1.78 9.17 0.0824.48 17.86 -0.77 -1.73 -0.0154.24 16.22 1.00 2.87 0.0264.21 14.58 0.11 0.04 0.0004.18 12.93 0.10 0.03 0.0004.17 11.29 0.03 0.00 0.0004.09 9.65 0.20 0.12 0.0013.31 8.01 1.68 8.09 0.0723.39 6.37 -0.14 -0.06 -0.0010.01 0.014.67 21.96 0.42 1.68 0.015

Assumptions/Problems in Velocity Profile measure of

Shear Stress

• Uniform bed surface and predictable interface velocities based on particle size.

• Theoretical curve based on uniform flow (and implications from river bedforms)

• Doppler velocities limited by technique: unable to read velocities at the top and bottom 5 feet of the profile.

Stream Slope Calculations for Shear Stress

• Data available from USGS via internet.

• Variety of stream flow conditions available.

• Yields an averaged shear stress for a particular stream reach.

• Influenced by stream characteristics: bedforms, obstructions, curves.

Inferring Maximum Shear Stress by Bedload Transport

• Larger shear stresses required to move larger rocks.

• Smaller shear stresses required to move gravel and sand.

• Data available to indicate minimum shear stress to move riverbed particles: sand 0.2 Newtons/sq. meter; gravel 3 N/sq. m

Figure 2: Particle Size Distribution Analysis-Riverbed and Suspended SolidsUSGS Data, 1979-1982, Ohio River at Louiville

0

20

40

60

80

100

120

0.001 0.01 0.1 1 10 100

Particle Size

Per

cen

t P

assi

ng

SS -11/30/1979

SS -6/10/1981

SS-1/27/1982

bed-1375' from KY bank










SS-6/2/82 mid-stream

SS-6/2/82 Ind side

Suspended Solids Indiana side Riverbed

Main channel and Kentucky side Riverbed

Flow = 301,000 to 434,000 cfsTSS = 482 to 698 mg/l

Flow= 239,000 cfsTSS=408-466 mg/l

Future Work at LWC

• Direct measure of riverbed conductivity

• Analysis of additional streams under varying conditions

• Influence of barges?

Shear Stress: Definition

• Shear stress is the resistance imparted by a fixed surface (streambed) on a moving fluid.

• This is similar to the friction forces at work in pipe headloss, and provides for the “head loss” in river system.

• Units: Newtons/sq. meter; psi/sq. foot

• Occurs when shear stress imparts a force on the riverbed adequate to move the particles of the riverbed.

• Is a function of stream velocity at the riverbed, and the particles (size, shape, density) making up the riverbed itself (sand and gravel).

Riverbed Scouring

Comparison of Models

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-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0 20 40 60 80 100 120 140 160 180 200

Time in Weeks

Speci

fic C

apaci

ty (

norm

al t

o m

ean)

Temp only: Cs = -.323 + .0024 Well T + .0026 River T R=.39, F=16Linear time: Cs = -.21 + .0036 Well T + .0014 River T - .0012 Time R=.61, F = 36Log time: Cs = 0.070 + .0018 Well T + .0018 River T - .070 time R=.61, F=36

Actual Data

Linear Time

Log Time

Temperature Only

N

Ohio River

L3 L6

L4 L5

L7 L2

M1

M2

M4

M3

L1

Well

Lateral

Figure 4.3 Locations of Area-wide Water Quality Sampling Wells

200 Ft

240 Ft

100 Ft

Steve Hubbs & Tiffany Caldwell University of Louisville Clogging in Louisville.

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Transcript of Steve Hubbs & Tiffany Caldwell University of Louisville Clogging in Louisville.