Water Power and Dam Construction

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WWW.WATERPOWERMAGAZINE.COM JULY 2009 31

sites based on basin delineation regression equations (Figure 5).

In some US states StreamStats is capable of estimating seasonal

and/or average annual streamflow. The Oregon version of

StreamStats is only capable of estimating peak streamflow events.

The smallest maximum instantaneous streamflow event the Oregon

version is able to estimate is a two-year peak flow event.

Peak flow events are generally not a good indicator of average

annual or seasonal streamflow, but they are better than no data at

all. In this case, the geographic, climatic, and stream monitoring char-

acteristics of the study area allow some generalizations to be made

from the StreamStats two-year maximum instantaneous flow data.

There are 10 streamflow gauging stations on unregulated rivers

and streams within the Clackamas County study area. Data from

these gauging stations was analyzed to determine the range of vari-

ation between average annual and peak streamflow events.

Depending on the relative frequency of the peak event and the area

of drainage involved, streamflow during peak events ranges from

12 – 129 times greater than average annual flow (see Table 1).

In the interest of creating conservative estimates, the upper end of

this range was used to process the average annual streamflow at the

identified study points. USGS estimated two-year peak flow values at

the analysis points were divided by 129 in order to derive an average

annual flow estimate. That flow estimate was again divided by 4 to

reflect the on-the-ground reality in Oregon that state environmental

agencies are unlikely to allow a run-of-river hydro power site to divert

more than 25% of streamflows for hydro power production.

Using the estimated elevation change and the estimated average

annual streamflow data, theoretical power was calculated for each

point using the following equation:

Where:

P = power in kilowatts,

Q = flow in cubic feet per second,

H = head in feet,

11.81 = the constant for converting flow and head to kilowatts,

e = the efficiency of the plant, considering head loss in the

pipeline and the efficiency of the turbine and generator,

expressed by a decimal

For the purposes of conservative estimates H was multiplied by 0.8

RESEARCH & DEVELOPMENT

ultnomah Hood River

Marion

Old Baldy

Creek

Table 1. Data from gauging

stations on unregulated streams

in Clackamas County.

Creek River Drainage Years of Avg Peak Multiplier

ame Mile Area record Flow Flow

(square mi) (cfs) (cfs)

Nate 0.9 0.6 5 1.4 32 23.7

Creek

ributary

Bull 0.43 0.7 14 1.9 250 128.9

Creek

Kelly 0 4.7 7 6.8 247 36.2

Creek

Johnson 16.3 15.4 9 29.7 835 28.1

reek 1

Johnson 10.2 26.8 67 53.2 2,620 49.2

Creek 2

Blazed 3.78 8.2 45 57.4 2,610 45.5

lder Creek

Johnson 0.7 53.2 18 76.7 2,170 28.3

Creek 3

Pudding 23.4 314.0 10 808.0 9,500 11.8

River 1

Molalla 6.01 323.0 53 1,140.0 43,600 38.2

River

Pudding 8.11 479.0 45 1,237.0 43,700 35.3

River 2

Above – Figures 3 and 4: The study area showing the analysis points,

streams, and private land, figure 4 shows more detail of the analysis and

includes shaded relief to show elevation change

Below – Figure 5: The USGS StreamStats application showing an example

basin delineation used to estimate streamflow. The green point is the point of

flow estimation. The pink highlight shows the automated basin delineation

used in the model’s regression calculations.

32 JULY 2009 INTERNATIONAL WATER POWER & DAM CONSTRUCTION

RESEARCH & DEVELOPMENT

to account for probable head losses and e was assumed to be 60%.

These estimates were used to create a visual representation of the

potential capacity of the identified sites (Figure 6).

Following the power generation estimation, the individual sites

were screened to determine their distance from power distribution

lines. Energy Trust was only interested in sites that could potential-

ly be integrated into the existing power grid. The local electric util-

ity, Portland General Electric, provided data on power line locations

and the phases available on those lines (single, two phase, or three

phase). All sites with an estimated power potential greater than or

equal to 1kW located within 2000ft (610m) of any power line,

regardless of phase, were included in the results (Figure 7).

Following this p rocess, the result s were an alyzed and checked

for errors.

ESULTS

A total of 1812 potential site points were identified by the GIS analy-

sis. Of those, 396 sites had a power potential greater than 1kW and

were within 2000ft (610m) of a power line. Those sites were scru-

tinized to check for errors.

The error checking process identified some major problems. As

an initial check, the identified points were overlaid with the pro-

tected streams layer to make sure sites were not incorrectly identi-

fied. In that test, many of the identified points appeared to be very

close to protected streams (Figure 8).

A close up view shows that the identified sites are not actually on

he protected streams, just nearby (Figure 9).

More closely checking these sites near to protected streams uncov-

ered a major error in the streamflow estimation process.

The StreamStats application works by projecting peak flow events

as they relate to precipitation and the area of drainage in a particu-

lar basin. StreamStats returns data indicating the number of square

miles drained at the poin t of streamflow estimation. As shown

above, many of the sites identified in this study were on small trib-

utaries very close to a major stream or river. In many cases,

StreamStats automated basin delineation process selected the major

stream or river instead of the small tributary. Examining the drainage

data, it is relatively easy to see points on small tributaries that do

not correlate with large areas of drainage. The streamflow estimates

at sites like these are for the main river and do not reflect the tribu-

taries’ flow. This invalidates the results at sites where this occurred.

To determine the scope of impact of the above error, all 396 sites

were examined to see if the reported area of dr ainage h ad a rea-

sonable correlation with the apparent length of the trib utary or

Figure 6: The identified sites shown by estimated generation

capacity. Larger points represent a higher capacity

Figure 7: The identified sites overlaid with power line data,

in pink, as provided by the local utility

Figure 8: The identified sites overlaid with protected streams in red. Major

areas of overlap appear

Figure 9 – A close up view shows the identified points and a protected river in

red. The main river is also shown in the blue stream layer, a higher resolution

data set. Note that the identified sites are on small tributaries very close to

where they enter the main river

WWW.WATERPOWERMAGAZINE.COM JULY 2009 33

RESEARCH & DEVELOPMENT

stream. Of those 396 sites, 231 appeared to be inaccurately delin-

eated by StreamStats. Those sites were eliminated from the study

results (Figure 10).

A second error check was performed to determine if site owner-

ship would preclude potential development. A total of 45 sites were

eliminated due to poor ownership status. A majority of these sites

were owned by the federal government and should have been elim-

inated earlier in the GIS process. A smaller portion of the sites were

removed because they were owned by large timber companies. It

was judged that these owners would be unlikely candidates for the

development of a micro hydro project.

Of the remaining 120 sites, the largest was estimated to be 23kW.

The next four largest sites were estimated at 9, 6, 5, and 4kW respec-

tively. Eight 3kW sites and thirteen 2kW sites were also identified.

The remaining 94 sites were all estimated to be 1kW.

A final check was performed on the sites greater than 4kW. None

were within 2000ft (610m) of a three-phase power line, which may

reduce development potential due to three-phase to single phase con-

version inefficiencies (Figure 11).

ONCLUSION

Environmental protections across Oregon’s stream systems appear

to acutely limit the potential to develop run-of-river micro hydro

esources in the study area. These highly regulated stream systems

are the legacy of the environmental, cultural, and recreational issues

created by the Pacific Northwest’s large hydro installations.

This study found only four potential sites in Clackamas County

with estimated power capacities greater than or equal to 4kW.

However, study errors markedly limited accurate site identification

and additional sites might have been found in the absence of these

errors. Without further investigation it is impossible to know if other

potentially viable sites exist in the county, but given the scale of reg-

ulation on the stream system any additional sites are likely to be few

in number and small in power potential.

For Energy Trust, these results will focus the organization’s hydro

outreach activities on potential sites where water is already allocat-

ed in an existing water right.

This GIS methodology appears sound with regard to estimating

head at potential sites, but was prone to errors in estimating stream-

flow. Further iterations on this techniqu e might improve perfor-

mance and/or reliability.

Four factors could be tested to attempt to improve the study

methodology:

• This study arbitrarily limited the analysis to streamflow segments

that had an elevation change of at least 10m over a 350m hori-

zontal run. The reason for this was to limit the overall number of

points in this data-intensive analysis. This artificial limit may have

eliminated some potential low-head sites with adequate flow while

favoring higher-head sites with inadequate flow.

• Many potential sites identif ied in this process were located on

tiny tributaries (less than 500m long). Estimates of power poten-

tial at t hese types of site s were often less than 1kW. Utilizing a

lower resolution stream data set that focused on larger streams,

not tiny tributaries, could have eliminated these low-power or

no-power sites. A nother method to red uce the identification of

these types of sites could be to set a minimum stream length for

inclusion in a study.

• Manually delineating stream basins in StreamStats could poten-

tially eliminate major errors in the streamflow estimation process.

Lack of time and resources prevented a test of this methodology.

Utilizing a different stream flow estimation technique could also

provide different results.

• Though not included in the current study, on-the-ground sampling

could also be done to ground truth power potential estimates at

sites that appear promising.

Variants on this method ology might b e useful in other locations

where StreamStats data exists or, utilizing a different streamflow esti-

mation technique, in other nations to help identify potential micro

hydro sites.

Jed Jorgensen is a Renewable Energy Project Manger at

the Energy Trust of Oregon, Inc., an independent

nonprofit organization dedicated to energy efficiency and

renewable energy development.

Email: jed.jorgensen@energytrust.org

128

127

Above – Figure 10: This is an example image from the drainage error checking

process. Sites 125 and 127 had reasonable drainage numbers. Site 128 had a

drainage area similar to the other sites, indicating that its delineation was

not done correctly

Below – Figure 11: The 120 potential sites identified by the study. The vast

majority (94) are 1kW in capacity. Only four of the identified points are larger

than 4kW. The largest is 23kW

IWP& DC

NTERNAL erosion of dams is the process of washout of fine-

grained particles from a dam’s filling material by seepage.

Internal erosion initiates generally by concentrated leak erosion,

backward erosion, and/or suffusion. In the continuation phase

it typically manifests itself by the formation of sinkholes, and sudden

increased muddy leakage. For internal erosion to occur it generally

requires: i) sufficiently large seepage; ii) a fill unable to retain its fines

(fine-graded particles); and iii) an interfacing material unable to filter

its base. Provid ed that the core-foundation contact is adequately

treated (Ripley, 1988), a dam’s downstream filter is generally con-

sidered the most important protection against internal erosion.

Despite the critical importance of filters, during the 1960s and

1970s – the peak period of modern dam construction – there were

still uncertainties in criteria in terms of filters protecting cores of

broadly graded soils. In ad dition, it appears there was an over-

reliance on broadly graded soils’ ability to “self-heal” (i.e. the core

itself being able to self-filter and stop movement of its fine-grained

particles), which in turn seems to have induced a trend of using a

single filter downstream of the core instead of multiple transition

layers. Dams in Scandinavia, parts of North America and Russia (i.e.

dams erected in areas once glaciated) are typically the type of dam

composed of broadly graded glacial materials (see Figure 1).

Although there has been significant development in the field of

internal erosion assessment, internal erosion in dams composed of

broadly graded glacial material remains fairly difficult to analyze

(Rönnqvist, 2006). In order to improve the understanding of inter-

nal erosion in this type of dam, this paper studies the long-term

behaviour of 30 dams afflicted with internal erosion. The objective

of this review is to investigate: i) typical signs and observations of

internal erosion; ii) the timing of internal erosion incidents; iii) the

possible early-warning signs; iv) the possible warning-time; and v)

the location of the internal erosion incident on the dam body. A

better understanding of such factors may provide possible tell-tale

signs of dams vulnerable to internal erosion and thereby aid in judg-

ment and tools for early-warning of internal erosion in existing dams

composed of broadly graded glacial soils.

In Foster et al. (2000) embankment dam incidents are closely stud-

ied, and they conclude that dams with glacial cores are more likely

to experience piping accidents than dams constructed of other mate-

rials, but that piping is less likely to lead to failure. This paper elab-

orates further into dams comprising broadly graded glacial soils and

their long-term behaviour in terms of internal erosion.

Notation and terminology used in this paper is as follows: DF15

– particle size in filter for which 15% by weight is finer; dB95 – par-

ticle size in the core base soil for which 95% by weight is finer; fines

– percent finer than a particle size of 0.075mm.

ILTER CHARACTERISTICS

Gradings are plotted in Figure 2 of the coarse limits of the filters of

dams that have had incidents related to internal erosion (e.g. sink-

hole formations). Also in Figure 2, the Sherard & Dunnigan (1989)

filter criterion DF15 ≤ 0.7mm is plotted, which by testing (Foster &

Fell, 2001) has been found to be the no-erosion-boundary for base

soils with fines content 35-85% (soil group 2A and glacial soils).

The continuing erosion boundary, i.e. DF15 > 9xdB95 (as proposed

by Foster & Fell, 2001), is the limit beyond which the filter is too

coarse to be sealed by the fines eroded from the core, and thereby

the majority of the i mpervious core may erode through the fi lter.

Based on the dams reviewed in this paper, the continuing erosion

boundary is approximately DF15 = 10.0 mm (if the core is regrad-

ed on the 4.75mm sieve), and as shown in Figure 2, only a few of

the filters of dams with internal erosion incidents (i.e. sinkholes) are

excessively coarse (coarser than the continuing erosion boundary).

The majority of the filters’ DF15 falls within the range between the

no-erosion boundary and the continuing erosion boundary.

In Rönnqvist (2008) the following set of indicators, typical of

dams that have experienced internal erosion, are proposed: a coarse-

ly graded filter (generally DF15 ≥ 1.4mm, as plotted in Figure 2);

grading instability of the core and filter; a filter susceptible to seg-

regation; and insufficient filter-transition components to the shell (in

RESEARCH & DEVELOPMENT

34 JULY 2009 INTERNATIONAL WATER POWER & DAM CONSTRUCTION

Moraine

(Till)

core

Filter

Shell

100

Passing weight (%)

0.002mm 2.0mm 60mm

No 200 sieve

0.075mm

Silt Sand

Grain size

Gravel

Figure 1: Typical dam

cross-section and

gradings of broadly

graded material s

In a paper in an upcoming issue of IWP&DC’s sister journal, Dam Engineering,

30 existing dams comprising broadly graded glacial soils with performance history

of internal erosion are reviewed with regards to the dams’ long-term behaviour.

Here, author Hans F Rönnqvist provides a summary of the extensive paper.

For case histories of reviewed dams, readers are referred to Dam Engineering

Long-term behaviour of

dams with internal erosion

WWW.WATERPOWERMAGAZINE.COM JULY 2009 35

terms of rockfill dams). Such unfavorable filter characteristics may

adversely affect the filter’s as-placed properties (such as the ‘effec-

tive’ DF15-value), which may explain why filters perform poorly,

although without excessively coarse gradings. Unstable gradings of

soils may cause redistribution of fine-grained particles within the

soil (given high enough seepage). Furthermore, depending on the fil-

tering ability of the connecting downstream zone to the filter, or

rather the lack thereof, there is also a risk for piping of filter fines

into its downstream zone.

The investigated piping accidents involving glacial core materials

in Foster et al. (2000) were generally attributed to the use of coarse

or segregated filters. The guidelines for assessing potential for seg-

regation of soils are less clear, but Foster & Fell (2001) found that

soils with maximum particle size coarser than 75mm, and low on

sand (less than 40% finer than 4.75mm) are highly susceptible for

segregation. The filters in Figure 2 may have segregated during han-

dling, since the maximum particle exceeds 75mm in many of the fil-

ters, and all of them are low in sand content. In order to limit the

risk for filter segregation, Ripley (1986) suggests an upper limit of

particle size in filters of 18mm and also a high content of sand frac-

tion (at least 60% to be finer than 4.75mm).

IMING OF INTERNAL EROSION RELATED INCIDENT

The timing of the first internal erosion incident refers to the elapsed

period of time from the dam being put into service to the first clear

sign of continuing internal erosion. Internal erosion in the continu-

ation phase usually manifests itself in a sinkhole on the crest of a

dam, and is usually formed by way of a large, progressive concen-

trated leak erosion, backward erosion and/or suffusion.

In close agreement with Foster et al (2000); the timing of the inter-

nal erosion incident of dams analyzed in this paper indicates that the

majority of incidents occur on first filling or during the first year of

operation (Figure 3). Out of the 30 dams analysed, 13 of those were

found to have an internal erosion incident that occurred in the early

life of the dam, with rockfill dams accounting for the majority of

these cases (10 dams). This may be influenced by the fact that most

of these rockfill dams are dams with i) coarsely graded potentially

unstable filters, ii) filters potentially susceptible to segregate, and iii)

no filter-transition component to the rockfill shell (which are char-

acteristics suggested in Rönnqvist (2008) as possible indicators of

internal erosion prone dams).

However, there are still a notable number of dams (more than

25%) where internal erosion surfaced after 10 years of service or

more (see Figure 3). Such examples point out that an older dam can

also experience the first signs of internal erosion.

OSSIBLE EARLY

WARNING SIGNS

Figure 4 shows the observed signs prior to an incident of internal

erosion. There may be several surfacing signs leading up to an inter-

nal erosion incident. Based on the dams reviewed in this paper, the

most common signs of internal erosion (which have led to an inci-

dent with sinkhole development) are: i) increase in leakage; and ii)

muddy leakage. T hese signs were also identified b y Fost er et al

(2000) as being the most common.

However, pore-pressure variations in the dam may also indicate

internal erosion (Figure 4). Other noted signs are concentrated leaks

at the toe of the dam and near-hydrostatic pressures in the core.

There are also dams for which there has been no apparent warning

sign prior to the forming of sinkholes.

The signs in Figure 4, if observed at an early stage, may indicate

the initiation of internal erosion in a dam, and furthermore, if it re-

occurs or progresses, they may also indicate the potential continua-

tion of internal erosion. The time-span from the first indication (e.g.

leakage-increase, clear seepage turning muddy, or notable pore-pres-

sure variations) to the incident (formation of sinkhole) may provide

a possible ‘warning time’. Such a warning is important from a dam

safety perspective, especially in terms of monitoring and surveillance

periodicity. Based on the 30 dams reviewed in this paper, there is

generally a matter of months or longer between the f irst possible

sign of internal erosion to the incident (Figure 5).

If the possible ‘early-warning’ time is subdivided into dam zoning

types (rockfill and earthfill dams, and homogenous sections), rock-

fill dams acc ount for the majority of cases where there is a short

period of time between the first sign and the incident of internal ero-

sion (Figure 5). Many of the rockfill dams included in this study are

composed of only a single filter zone between the core and the shell,

which may partly explain the short warning time to the incident.

However, there are still a number of rockfill dams for which there

are a number of months between the first sign of internal erosion

and the incident.

In terms of the earthfill dams reviewed in this paper there is gen-

erally a period of months, in some cases years, between the first sign

RESEARCH & DEVELOPMENT

100

Passing weight (%)

Grain size (mm)

0.1 1 10 100 1000

0.2 0.6 2 6 20 60 200

15<=0.7mm

Sherard & Dunnigan (1989)

D15>=1.4mm

Rönnqvist (2008)

15 (filter)>9d95

(

base) = approx.

0mm (ie. fine

imit of cont.

rosion boundary,

oster & Fell, 2001

Figure 2: Filter gradings (coarse limits) of dams which have had internal

erosion incidents

First filling

st year

Year 1-5

Year 5-10

ear 10-20

Year 20-

Time until internal erosion incident

0 1 2 3 4 5 6 7 8 9

umber of cases

Rockfill dams Earthfill dams Homogenous section

Possible early warning signs

Number of cases

Unknown

o warning signs

Increase in leakage

Pore-pressure variations

Muddy leakage

Settlements

Concentrated leaks

Hydrostatic pressure in core

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Figure 4: Early-warning signs preceding sinkhole

Figure 3: Elapsed time until first internal erosion incident

36 JULY 2009 INTERNATIONAL WATER POWER & DAM CONSTRUCTION

RESEARCH & DEVELOPMENT

of internal erosion and the incident. This suggests a longer progres-

sion-time from the initiation of internal erosion to the continuation

phase (at which sinkholes form).

OCATION OF INCIDENT

Foster et al (2000) concluded that conduits through the embank-

ment have the most important influence on the initiation of piping

(especially for dam s with limited zoning); wit h other locations

including contacts with concrete structures, over foundation irreg-

ularities, and steep abutments, but these are less frequent.

For the majority of the cases reviewed in this paper, the location

at which internal erosion surfaced is unknown or randomly located

over the soil or rock foundation. However, in close agreement with

Foster et al (2000), locations with higher incidence of surfacing inter-

nal erosion are: i) where embankments abut to concrete structures

or sheet pile walls; and ii) where the core is placed on steeply inclined

foundation. From experience, these are locations difficult to com-

pact, and are generally more susceptible to hydraulic fracturing and

differential settlements (Foster et al, 2000).

ONG

TERM BEHAVIOUR

In this paper, 30 existing dams comprising broadly graded soils (of

glacial origin, i.e. moraines and tills) are reviewed. These are all dams

that, to differing extents, have experienced incidents of internal ero-

sion. Based on the reviewed dams, the table opposite summarises

the long-term behaviour of internal erosion afflicted dams.

Incidents are most likely to occur early-on, since almost half of the

dams reviewed experienced incidents during first filling or within the

first year of service. However, without any previous signs, there are

dams that experience first signs of internal erosion decades into oper-

ation. When not randomly located over soil and rock foundation, the

surfacing of the internal erosion incident has been found in this review

to occur where dams abut to concrete structures or sheet pile walls,

and over foundation irregularities, as discussed by Foster et al, 2000.

The most common signs that precede an internal erosion related

incident are: increase in leakage; muddy leakage; and pore-pressure

variations in the dam body (although less frequently observed). Such

signs may be early-warnings of initiated and progressive internal ero-

sion. Note tha t there are also dams to which there has been no

apparent warning-sign prior to the formation of sinkholes. Generally

there is a warning time of a number of months, or longer, between

the first sign of internal erosion and the incident. However, rockfill

dams account for the majority of cases where there has been a rela-

tively short period of time between the first sign and the incident of

internal ero sion. Monitoring and surveillance are key features in

ensuring reservoir safety. Based on the review of existing dams, this

paper s hows that there may be a relatively short period o f time

between the first signs of internal erosion and a potential incident.

In order to detect and understand the signs of internal erosion, mon-

itoring needs frequent follow-ups to detect changes in trends and

patterns. Furthermore, observations during visual inspections need

continuous cross-referencing with the monitored data.

Hans F. Rönnqvist, Post-graduate Student, the Royal

Institute of Technology, Stockholm, Dep. of Land and

Water Resources Engineering, Hydraulic Engineering.

hansro@kth.se

The research presented in this paper has received financial

support from the ”Swedish Hydropower Centre – SVC”.

Further information is available on www.SVC.nu

Full details of this study will be published in Volume XX

Issue 1 of Dam Engineering. For further information on

this journal contact Tracey Honney via email:

thonney@progressivemediagroup.com

IWP& DC

References

Foster, M.A., Fell, R. (2001) Assessing Embankment Dam Filters that do

not satisfy Design Criteria, J. of Geotech. and Geoenv. Engrg, Vol. 127, no.

4, May, pp. 398-407.

Foster, M., Fell, R., Spannagle, M. (2000) The Statistics of Embankment

dam failures and accidents, Can. Geotech. J., vol. 37, pp. 1000-1024.

Ripley, C., F. (1986) Internal Stability of Granular filters: Discussion, Can.

Geotech. J., vol. 23, pp. 255-258.

Ripley, C. F., (1988) Comments on Q. 61- R.29 and R. 55, 16th ICOLD

Congress, San Francisco, vol. V, Minutes, 1988.

Rönnqvist, H. (2006) Predicting Internal Erosion in Glacial Moraine Core

Embankment Dams, Pr oc. of Hydrovision 2006, Portland, OR, USA.

Rönnqvist, H (2008): Review of moraine core dams and internal erosion,

Dam Engineering, Vol. XIX Issue 2, pp. 99-121

Sherard, J.L. and Dunnigan, L.P. (1989) Critical filters for impervious soils,

J. of Geotech. Engrg, ASCE, 115 (7), pp. 927-947.

Long-term behaviour of dams that have

experienced internal erosion (sinkholes)

Rockfill dams Earthfill dams

Timing of internal Generally during first Generally a few years

rosion incident: filling or within first year. into operation or

here are also rockfill after several years.

dams where incidents

occurred years into

operation.

However, first signs of internal erosion may also occur

decades into operation (irrespective of dam zoning).

ossible Increase in leakage

early-warning sign:

Muddy leakage

Pore-pressure variations

Possible warning-time Account for the majority Generally months or

between first sign of dams with no warning, longer between first

nd internal erosion or up to days–weeks sign and the incident.

incident: “warning-time”.

However, there are also

ockfill dams where there

have been months or

onger “warning-time”.

Location of internal Higher incidence where dams:

erosion incident: i) Abut to concrete structures and/or sheet pile walls

ii) Are placed on ir regular foundation.

Time between early-warning sign

and internal erosion incident

0 1 2 3 4 5 6 7 8 9 10 11 12 13

Number of cases

Unknown

No warning time

Days-weeks ahead

onths ahead

Rockfill dams Earthfill dams Homogenous section

Figure 5: Possible warning-time before the internal erosion incident (sinkhole)

WWW.WATERPOWERMAGAZINE.COM JULY 2009 37

RESEARCH & DEVELOPMENT

“We have already conducted public meetings and site visits in the

area of these sites, and we anticipate performing environmental stud-

ies at them as well,” Lissner says. “The information we get from

these will be relevant to the filing of our licence applications for our

other sites through FERC’s traditional licensing process.”

Using a combination of traditional and integrated licensing process-

es will enable FFP to address the environmental issues, as well as the

effects of the whole system. Lissner says: “We believe that this process

is the most effective way for us to address the concerns of all of the

stakeholders, wherever they are located geographically.”

FFP plans to file licence applications for its Mississippi river pro-

jects by the end of 2010. It has also just completed a series of public

meetings and site visits at the lead sites, and is working with the reg-

ulatory agencies to determine what environmental tests need to be

done. These tests should be carried out next year. At the present time

FFP is working on deploying a turbine on a barge in the Mississippi

river to continue gathering operational data.

For more information contact Daniel Lissner, Free Flow

Power Corporation. Email : dlissner@free-flow-power.com

S COMPANY Free Flow Power (FFP) is well on its way

to developing extensive hydrokinetic facilities in the US.

FFP’s engineering and hydrology team began evaluating

the hydrokinetic potential of US rivers in early 2007. After

studies of more than 80,000 possible sites the company decided to

focus on the Mississippi river for its initial projects.

The Mississippi river basin drains 40% of North America. It is

the largest available source of river energy in this region and has

been described as being top in terms of flows and volumes. Its impor-

tance as a navigational resource has limited the development of

hydroelectric facilities in its lower reaches, preserving the opportu-

nity for hydrokinetic development. FFP’s largest grouping of sites

that share many of the same ecological characteristics are located

on the Lower and Middle Mississippi river.

“Each site varies in terms of depth and size, but generally we are

targeting an installation of 6MW per mile, or 600 turbines, in areas

that are large enough to locate the turbines without interfering with

navigation or other uses of the river,” Lissner says. “We have

designed our turbines to be small enough to deploy them in a vari-

ety of arrays, such as vertically on a pylon, horizontally between two

pylons, or suspended from the surface from barges.”

REPARATION AND PLANNING

In 2008 FFP obtain ed 55 preliminary permits from the Federa l

Energy Regulatory Commission (FERC) for hydrokinetic projects

in seven states along the Mississippi river, as well as additional per-

mits for projects on the Missouri and Ohio rivers. A FERC prelim-

inary permit enables a company to study the characteristics of these

sites in preparation for filing a licence application, which must be

done within three years of the permit’s issuance. During this time,

FFP will be gathering data about the sites, conducting outreach to

stakeholders, and performing tests and studies that are necessary to

prepare the application for a licence.

Currently FFP has seven ‘lead sites’ on the Lower Mississippi at

which the company is using FERC’s integrated licensing process –

the aim of which is to promote discussion and environmental stud-

ies before a licence application is filed. These sites were designated

as lead sites because they have environmental characteristics that are

representative of the whole river system.

Free Flow Power is utilising untapped hydrokinetic energy on the Mississippi river in the US

Powering up the Mississippi

IWP& DC

Turbine development

FFP has developed an integrated turbine generator system - the SmarTurbine

generator - with a rim-driven generator, one moving part, and forward and aft

shrouds to laminate and accelerate flow. This technology includes

microprocessors to provide remote monitoring of turbine performance and to

vary the generator load in various flow velocities to optimise turbine

performance. The rotor is designed to operate over a wide range of flow

velocities. A 1.4m diameter version of the SmarTurbine generator was tested

at Alden Labs and is being field tested in various environments. A 3m diameter

version of the will be field tested in 2009. A 3m device generates 10kW in

flows of 2.25m/sec, while a 1m device generates 10kW in flows of 3m/sec.

Key design featur es include: Low tip speed ratio to eliminate fish injury from

mechanical strike; No high velocity regions to cause turbulent sheer stress;

No small gaps that would cause grinding injury; Deployment below the

navigation channel, off the riverbed; Minimal onshore equipment;

Hydrodynamic bearing system designed to resist wear from silt and sand,

eliminating the need for chemical lubricants.

Left to right: Artist’s impression of six turbines on a piling;

four turbines in vertical assembly; the test unit at Alden Labs

PROFESSIONAL DIRECTORY

38 JULY 2009 INTERNATIONAL WATER POWER & DAM CONSTRUCTION

CLASSIFIED

www.waterpowermagazine.com

MORE THAN 100 YEARS OF HYDROPOWER ENGINEERING

AND CONSTRUCTION MANAGEMENT EXPERIENCE

260 Dams and 60 Hydropower Plants (15,000 MW)

built in 70 countries

Water resources and hydroelectric development

• Public and private developers

• BOT and EPC projects

• New projects, upgrading and rehabilitation

• Sustainable development

with water transfer, hydropower, pumping stations

and dams.

CO Y NE ET B E LL IER

9, allée des Barbanniers

92632 GENNEVILLIERS CEDEX - FRANCE

Tel: +33 1 41 85 03 69

Fax: +33 1 41 85 03 74

e.mail: commercial@coyne-et-bellier.fr

website: www.coyne-et-bellier.fr

COYNE ET BELLIER

Bureau d’Ingénieurs Conseils

ww w. coyne- et-b elli er. fr

Over 40 years experience in Dams.

CFRD Specialist Design and Construction

●

am Safety Inspection

●

Construction Supervision

●

Instrumentation

●

RCC Dam Inspection

●

Panel Expert Works

v. Giovanni Gronchi, 5445 sala 172, Sao Paulo –

razil

IP Code – 05724-003

Phone: +55-11-3744.8951

Fax: +55-11-3743.4256

mail: bayardo.materon@terra.com.br

a_mater@yahoo.com.br

Lahmeyer International GmbH

Friedberger Strasse 173 · D-61118 Bad Vilbel, Germany

Tel.: +49 (6101) 55-1164 · Fax: +49 (6101) 55-1715

E-Mail: bernd.metzger@lahmeyer.de · http://www.lahmeyer.de

Your Partner for

Water Resources and

Hydroelectric Development

All Services for Complete Solutions

• from concept to completion and operation

• from projects to complex systems

• from local to multinational schemes

• for public and private developers

Norconsult AS

Vestfjordgaten 4,

1338 Sandvika, Norway

Tel: +47 67 57 10 00

Fax: +47 67 54 45 76

company@norconsult.com

Power and Water Management

Norconsult provides multidisciplinary

onsultancy services within power

nd water resources development.

www.norconsult.com

• River Basin Studies

•

Underground Hydropower

• Dam Design

• Turbine Maintenance and

Optimisation

• Transmission and Distribution

• Environmental Impact Assessments

• Financial Engineering

• Power Utility Services

AF-Colenco Ltd

Täfernstrasse 26 • CH-5405 Baden/Switzerland

Phone +41 (0)56 483 12 12 • Fax +41 (0)56 483 17 99

olenco-info@afconsult.com • http://www.af-colenco.com

Consulting / Engineering and EPC Services for:

• Hydropower Plants

• Dams and Reservoirs

• Hydraulic Structures

• Hydraulic Steel Structures

• Geotechnics and Foundations

• Electrical / Mechanical Equipment

formerly Electrowatt-Ekono and Verbundplan

Hydropower and Water Management with

Worldwide Experience and Local Presence

For further information please contact

hp.energy@poyry.com and visit www.poyry.com

Construction and

refurbishment of small

and medium hydro

power plants.

C p

udi

ﬁnanc

www.hydropol.cz

To advertise in the Professional Directory or

World Marketplace section or for more information

contact Diane Stanbury on tel: +44 (0)20 8269 7854

or email: dstanbury@progressivemediagroup.com

Copy deadline for August 2009 issue is 4 August 2009

I N T E R N A T I O N A L

& DAM CONSTRUCTION

Water Power

PROFESSIONAL DIRECTORY

WWW.WATERPOWERMAGAZINE.COM JULY 2009 39

CLASSIFIED

www.waterpowermagazine.com

Yolsu Engineering Services Ltd. Co.

Hürriyet Caddesi No:135 Dikmen, 06450 Ankara,TURKEY

Tel: +90 312 480 06 01 (pbx) Fax: +90 312 483 31 35

www.yolsu.com.tr info@yolsu.com.tr

Prefeasibilty, Feasibility,

Final & Detail Design,

Consulting Services:

• Basin development

• Dams and hydropower plants

• Irrigation and drainage

• Water suppl y and sewerage

• River engineering

• Highways and railways

Stellba Hydro AG Stellba Hydro GmbH & Co KG

Langgas 2 Badenbergstrasse 30

CH-5244 Birrhard D-89520 Heidenheim

Switzerland Germany

Telefon +41 (0)56 201 45 20 Telefon +49 (0)7321 96 92 0

Telefax +41 (0)56 201 45 21 Telefax +49 (0)7321 6 20 73

Internet www.stellba-hydro.ch Internet www.stellba.de

E-Mail info@stellba-hydro.ch E-Mail info@stellba.de

www.waterpowermagazine.com

The classified section in Water Power & Dam Construction

is a well established and popular section with the magazine’s

combined print and digital circulation of 16,000. Commonly

known as where “the buyer meets the seller”.

Classified

opportunities

For more information, please contact

Diane Stanbury Tel: +44 (0)20 8269 7854 or email: dstanbury@progressivemediagroup.com

Recruitment

The ideal way to promote a company vacancy and

reach experienced professionals looking for the next

opportunity to advance their career in the hydro power

& dam construction industries.

Industry showcases

The industry showcase section is made up of eighth

page adverts (95x65mm) with a maximum of eight key

suppliers to a page. It is an ideal section to promote

products and services, raise brand awareness and

shout about company successes. Showcase adverts

are also an ideal way to promote product literature and

generate interest.

Recommended duration: minimum 3 months

WORLD MARKETPLACE

40 JULY 2009 INTERNATIONAL WATER POWER & DAM CONSTRUCTION

CLASSIFIED

www.waterpowermagazine.com

CYLINDERS

Rexroth

Bosch Group

Bosch Rexroth B.V.

Cylinders

Application based standard cylinder designs for;

radial gates, roller and slide gates, butterfly and

ball valves, turbine regulation, navigational locks

nd movable bridges.

Bosch Rexroth B.V.

Contact: Mr Bob Lamers, Tel: +31 411 651 778

www.boschrexroth.com

Mail to: cylinders@boschrexroth.com

CRANES

GATES

HEAT EXCHANGERS

Enerfin Inc.

5125 J.A. Bombardier, St-Hubert

(Quebec) Canada, J3Z 1G4

Tel: + 1 450 443-3366

Fax: +1 450 443-0711

Email: sales@enerfin-inc.com

Website: www.enerfin-inc.com

HIGH QUALITY COOLERS FOR:

• Hydro Generators

• Thrust Bearings

• Transformers

• Synchronous Condensers

• Turbo Generators

• Air Preheaters, etc.

Custom Design To Suit Your Application

Extruded Fins

Providing water control solutions through thoughtful engineering,

innovative design, attention to detail and outstanding customer

service. Contact us for inflatable water control gates and rubber

ams.

PO Box 668, Fort Collins, CO 80522 USA

el: 970-568-9844

www.obermeyerhydro.com

• Custom Design Hydraulic Cylinders

• Servomotors

• Piston Accumulators'

•

Hydraulic Power Units

•

Control Panels

www.doucehydro.com

Douce Hydro FRANCE, USA and GERMANY

Tel France: + 33 / 3 22 74 31 08 ; E-mail: afleroy@doucehydro.com

el USA: + 1 / 586 566 4725 ; E-mail: fvandenbulke@doucehydro.com

Tel Germany: + 49 / 177 398 37 78 ; E-mail : ublase-henke@doucehydro.com

BEARINGS

PAN

bronzes

and

PAN

-GF

self-lubricating bearings

Since 1931

- Superior quality with

• Highest wear resistance

• Low maintenance

• Or maintenance free

Extended operating life

PAN-Metallgesellschaft

P.O. Box 102436 • D-68024 Mannheim / Germany

Phone: + 49 621 42 303-0 • Fax: + 49 621 42 303-33

ontakt@pan-metall.com • www.pan-metall.com

BEARING OIL COOLERS

EXECO, Inc. ... a H

at Ex

hanger E

gineering Co

el: +1 (920) 361-3440 • Fax: +1 (920) 361-4554

E-Mail: info.wpd@hexeco.com • Web: www.hexeco.com

IL COOLERS

For

THRUST and

GUIDE

BEARINGS

CONCRETE COOLING

• COLD & ICE WATERPLANTS

• FLAKE ICE PLANTS

• ICE DELIVERY & WEIGHING SYSTEMS

• ICE STORAGES

KTI-Plersch Kältetechnik GmbH

Carl-Otto-Weg 14/2

88481 Balzheim

Germany

Tel:/Phone: +49 - 7347 - 95 72 - 0

Fax: +49 - 7347 - 95 72 - 22

Email: ice@kti-plersch.com

Website: www.kti-plersch.com

CONCRETE COOLING

FILTRATION EQUIPMENT

Contact Diane Stanbury on:

+44 208 269 7854

dstanbury@

progressivemediagroup.com

For World Marketplace

advertising opportunities

WWW.WATERPOWERMAGAZINE.COM

kuenzamerica@kuenz.com

ww w.kuenzamerica. com

TRASH RAKE CLEANING

POWER HOUSE CRANES

Ame rica In c.

kuenzamerica@kuenz.com

www.kuenzamerica.com

TRASH RAKE CLEANING

POWER HOUSE CRANES

Ame rica In c.

Water Power and Dam Construction - Issue July 2009

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