Colorado River Ecosystem 

Sediment Augmentation 

Appraisal Engineering Report 
 

1

Mission Statements 

The mission of the Department of the Interior is to protect and 

provide access to our Nation’s natural and cultural heritage and 

honor our trust responsibilities to Indian Tribes and our 

commitments to island communities. 

The mission of the Bureau of Reclamation is to manage, develop, 

and protect water and related resources in an environmentally and 

economically sound manner in the interest of the American public. 
 

2

Colorado River Ecosystem 

Sediment Augmentation 

Appraisal Engineering Report

Prepared by 

Timothy J. Randle, M.S., P.E, 

Manager, Sedimentation and River Hydraulics Group 

Joseph K. Lyons 

Hydraulic Engineer, Water Resources Planning and Operations 

Support Group 

Rick J. Christensen and Ryan D. Stephen 

Mechanical Engineers, Mechanical Equipment Group 
 

3

Acknowledgements 

The following individuals contributed to this appraisal engineering report: 

Bureau of Reclamation, Technical Service Center 

• Tim Randle (overall guidance) 

• Joe Lyons (team leader) 

• Ron Ferrari (Lake Powell survey) 

• Jim Yahnke (water quality) 

• Fred Tan (pipeline design) 

• Steve Robertson (pipeline design review) 

• Rick Christensen (sediment dredging) 

• Richard Fehr (pumping plant design) 

• Lisa Gamuciello (electrical power) 

• Larry Rossi (electrical controls) 

• Jerry Zander (cost estimation) 

• Larry Pede (cost estimation) 

National Park Service 

• Norm Henderson (plan formulation) 

Internal peer review for this report was provided by Mohammed Samad, Ph.D., P.E., 

Hydraulic Engineer, Sedimentation and River Hydraulics Group. In addition, review 

comments were also provided by Ted Melis, Ph.D., Deputy Chief, Grand Canyon 

Monitoring and Research Center and three anonymous reviewers selected by the Grand 

Canyon Monitoring and Research Center. 
 

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Table of Contents 

1.0 Introduction............................................................................................................. 1 

1.1 Study objectives.................................................................................................. 4 

1.2 Sediment Augmentation Purposes ...................................................................... 4 

1.3 Previous Investigations ....................................................................................... 5 

2.0 Alternative Sediment Augmentation Systems ........................................................ 6 

2.1 Alternative Sediment Sources............................................................................. 7 

2.1.1 Navajo Canyon............................................................................................ 9 

2.1.2 Other Sediment Source Areas Not Considered in Detail.......................... 14 

2.1.3 Sediment Source Areas Eliminated From Consideration ......................... 14 

2.2 Alternative Sediment Delivery Locations......................................................... 15 

2.2.1 Below Glen Canyon Dam or near Lees Ferry........................................... 16 

2.2.2 Sediment Delivery Points Eliminated from Consideration....................... 18 

2.3 Alternative Sediment Collection Methods........................................................ 18 

2.4 Alternative Sediment Conveyance Methods and Alignments .......................... 19 

2.4.1 Slurry Pipelines......................................................................................... 25 

2.4.2 Sediment Conveyance Methods Eliminated from Consideration............. 30 

2.5 Sand Storage Alternatives................................................................................. 34 

2.6 Summary of Complete Alternatives.................................................................. 34 

3.0 Appraisal-level Cost Estimates............................................................................. 37 

4.0 Environmental Impacts ......................................................................................... 43 

4.1 Water Quality.................................................................................................... 43 

4.1.1 Regulations ...................................................................................................... 44 

4.2 Cultural Resources............................................................................................ 44 

5.0 Conclusions........................................................................................................... 46 

6.0 Future Investigations............................................................................................. 48 

7.0 References............................................................................................................. 49 

Appendix A − Sediment Quality....................................................................................... 52 

Appendix B − Dredging Text Research and Information................................................. 58 

Dredge Design Types.................................................................................................... 58 

Dredging Manufacturers ............................................................................................... 59 

Dredging ....................................................................................................................... 62 

Sediment Slurry Piping System ................................................................................ 66 

Trucking.................................................................................................................... 67 

Off Highway Trucking.............................................................................................. 67 

Conveyor Systems .................................................................................................... 70 

Appendix C - Stilling Basin Operations ........................................................................... 71 
 

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List of Tables 

Table 1. Alternative sediment augmentation features........................................................ 7 

Table 2. Lake Powell 1986 delta distances and sedimentation volumes (Ferrari, 1988 and 

Ferrari, Bureau of Reclamation, written communication, 2006)................................ 9 

Table 3. Feasibility summary of sediment delivery methods. ......................................... 20 

Table 4. Summary of alternative sediment slurry pipeline alignments. .......................... 25 

Table 5. Sediment slurry pipeline mass and volumentric flow rates. .............................. 28 

Table 6. Summary of complete sediment augmentation alternatives. ............................. 36 

Table 7. Summary comparison of appraisal cost estimates for five sediment 

augmentation alternatives. ........................................................................................ 37 

Table 8. Appraisal-level cost estimate for alternative 1 (January 2006 dollars). ............ 38 

Table 9. Appraisal-level cost estimate for alternative 2 (January 2006 dollars). ............ 39 

Table 10. Appraisal-level cost estimate for alternative 3 (January 2006 dollars). .......... 40 

Table 11. Appraisal-level cost estimate for alternative 4 (January 2006 dollars). .......... 41 

Table 12. Appraisal-level cost estimate for alternative 5. ............................................... 42 

Table 13. Comparison of the results from an ICP-MS scan of the Navajo Canyon 

sediment sample with crustal abundance values from 2 sources (all in ppm).......... 53 

Table 14. Comparison of sediment collected at upper reach of Navajo Canyon with EPA 

sediment quality guidelines (Ingersoll et al., 2000; MacDonald et al., 2000) .......... 54 
 

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List of Figures 

Figure 1. Location map of study area including Lake Powell, Colorado River, Paria 

River, Marble Canyon, Grand Canyon National Park, and the Navajo Nation.......... 2 

Figure 2. Close-up location map of Glen Canyon Dam, Lake Powell, Navajo Canyon, 

Antelope Point, City of Page, the Navajo Nation, Colorado River, Paria River, Lees 

Ferry, and Marble Canyon. ......................................................................................... 3 

Figure 3. Lake Powell and delta locations......................................................................... 8 

Figure 4. Longitudinal sediment profiles of Navajo Canyon. ......................................... 10 

Figure 5. Navajo Canyon delta surface near river mile 11 (18 km) on November 3, 2004.

................................................................................................................................... 10 

Figure 6. Longitudinal bottom profiles of Lake Powell (L. Pratson, Duke University, 

written communication, October 3, 2006). ............................................................... 12 

Figure 7. Detailed bathymetry at the mouth of Antelope Canyon shows a summarine fan 

deposit in the old Colorado River channel that extends longitudinally for a distance 

of one or two Colorado River canyon widths (L. Pratson, written communication, 

December 1, 2006).................................................................................................... 13 

Figure 8. Life expectancy of the Navajo Canyon sediment source as a function of the 

annual sediment augmentation rate........................................................................... 13 

Figure 9. Glen Canyon reach of the Colorado River between Glen Canyon Dam and Lees 

Ferry, Arizona........................................................................................................... 16 

Figure 10. Clamshell dredge excavating sediment. ......................................................... 19 

Figure 11. Alternative sediment slurry pipeline routes from Navajo Canyon to below 

Glen Canyon Dam and to Lees Ferry. ...................................................................... 21 

Figure 12. Plan-view map of the pipeline alignment from Navajo Canyon to Glen 

Canyon Dam (add 3.5 miles or 5.6 km to distances to determine the total pipeline 

length). ...................................................................................................................... 22 

Figure 13. Longitudinal profile of the pipeline alignment from Navajo Canyon to Glen 

Canyon Dam (add 3.5 miles or 5.6 km to determine total pipeline length).............. 22 

Figure 14. Plan-view map of the pipeline alignment from Navajo Canyon to Lees Ferry 

(add 3.5 miles or 5.6 km to distances to determine the total pipeline length). ......... 23 

Figure 15. Longitudinal profile of the pipeline alignment from Navajo Canyon to Lees 

Ferry (add 3.5 miles or 5.6 km to distances to determine the total pipeline length). 24 

Figure 16. Submerged sediment slurry pipelines............................................................. 26 

Figure 17. Pumping plants on Lake Powell would be floated on modular barges while 

pumping plants on land would be contained within permanent buildings................ 29 

Figure 18. There are no roads in the remote area of Navajo Canyon where bedrock rises 

1,000 feet (300 m) from the surface of Lake Powell. ............................................... 32 

Figure 19. Comparison of the concentrations of elements from the ICP-MS scan of 

Navajo Canyon sediments with concentrations typical of sandstone. ...................... 55 

Figure 20. Comparison of the concentrations of elements in duplicate samples of 

 Moqui Canyon sediments with concentrations typical of sandstone (Parker, 1967).56
 

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1.0 Introduction 

Colorado River sediment loads, through the Colorado River ecosystem below Glen 

Canyon Dam are substantially less today compared to natural conditions (U.S. 

Department of the Interior, Bureau of Reclamation, 1995). This Colorado River 

ecosystem is defined by the Glen Canyon Dam Adaptive Management Program as the 

river corridor extending from the forebay of the dam downstream to river mile 278. The 

primary reason for the reduction in Grand Canyon sediment load is the reservoir 

sedimentation in Lake Powell. Essentially, the entire sediment load of the Colorado 

River, upstream from Glen Canyon Dam, is trapped within Lake Powell (U.S. 

Department of the Interior, Bureau of Reclamation, 1995). 

Lake Powell is formed behind Glen Canyon Dam and is located on the Colorado River 

near the City of Page, in northern Arizona (see figures 1 and 2). Lake Powell backs up 

into southern Utah and has a total storage capacity of 27 million acre-feet (33 billion m3), 

which is 2.3 times the mean annual flow of the Colorado River. Based on the last 

complete reservoir survey in 1986, sedimentation in Lake Powell had reduced the storage 

capacity by 868,000 acre-feet (1.07 billion m3

), which is 3.2 percent of the total storage 

capacity of 27 million acre feet (33 billion m3) (Ferrari, 1988). Now, Colorado River 

tributaries below Glen Canyon Dam provide the only significant sediment source to the 

Grand Canyon. 

Since the completion of Glen Canyon Dam in 1963, annual sediment loads to the Grand 

Canyon stream gage have decreased from 91 ± 4 million tons per year (83 ± 4 million Mg 

per year), of which approximately 35% was sand, to 15 million tons per year (14 ± 1 

million Mg per year) (Topping et al, 2000a). Sediment can be classified by particle size 

and can include clay, silt, sand, gravel, and cobbles. This study is primarily concerned 

with sand and finer (silt and clay) sized sediments. The reduced sand loads and natural 

floods have reduced the number and size of sandbars in Glen, Marble, and Grand 

Canyons. The reduced fine sediment loads have resulted in less turbidity and less cover 

for native and endangered fish (U.S. Department of the Interior, Bureau of Reclamation 

1995). The augmentation of sediment loads to the Colorado River ecosystem may 

reverse some of the sediment related impacts caused by operation of Glen Canyon Dam. 

This study was funded by the Adaptive Management Work Group as part of the 

humpback chub comprehensive planning activities and programmed by the Grand 

Canyon Monitoring and Research Center as part of its mission to provide science support 

to the Glen Canyon Dam Adaptive Management Program. 
 

2

Figure 1. Location map of study area including Lake Powell, Colorado River, Paria 

River, Marble Canyon, Grand Canyon National Park, and the Navajo Nation. 
 

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Figure 2. Close-up location map of Glen Canyon Dam, Lake Powell, Navajo 

Canyon, Antelope Point, City of Page, the Navajo Nation, Colorado River, Paria 

River, Lees Ferry, and Marble Canyon. 
 

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1.1 Study objectives 

The objectives of this appraisal-level study are to investigate the engineering methods 

and requirements of sediment augmentation systems that would deliver sand, silt and clay 

to the Colorado River at alternative locations downstream from Glen Canyon dam. 

Alternative sediment sources, delivery methods, and points of delivery are evaluated and 

appraisal-level costs are compared. This appraisal-level study provides the necessary 

information to facilitate making decisions on whether or not to proceed with a detailed 

study and evaluation of any alternative. A detailed description of the physical and 

biological effects of sediment augmentation in Grand Canyon is beyond the scope of this 

investigation. 

1.2 Sediment Augmentation Purposes 

Grand Canyon sediment augmentation would have two primary purposes: 

1. Seasonally increase the turbidity of the Colorado River to provide cover for native 

and endangered fish during the months of May through December. This is the 

period when young-of-the year humpback chub emerge from the Little Colorado 

River and then rear in the Colorado River (U.S. Department of the Interior, 

Bureau of Reclamation, 1995). These native fish evolved in a turbid environment 

and may use it for cover from potential predators. 

2. Annually increase the sand supply to the Colorado River during beach-building 

flows to build larger sandbars, especially in Marble Canyon, through fluvial 

processes. 

The Colorado River turbidity objective is to continuously achieve a minimum suspendedsediment concentration for silt and clay-size sediments (fine sediment) each year from 

May through December. Fine sediment would not have to be added during times when 

the turbidity of the Colorado River has increased during floods from the Paria River. The 

mean annual sediment load from the Paria River at Lees Ferry, Arizona was 3.3 ±0.7 

million tons per year (3.0 ± 0.6 Mg/yr), of which about 50 percent was sand, for the 

period of sediment record (Topping et al, 2000a). During the period 1923 to 1986, twothirds of the Paria River annual peak discharge occurred in the months of August, 

September, and October. About than 90 percent of the Paria River annual sediment load 

occurs during the period July through October (Andrews, 1991). 

The minimum suspended-sediment concentration (for fine sediment) in the Colorado 

River that would benefit native and endangered fish has yet to be determined by fishery 

scientists, but is believed to be between 100 and 1,000 ppm. A concentration of 500 ppm 

is assumed for this study. At this concentration, the Colorado River would transport 

3.8 million tons (3.4 million Mg) of fine sediment per year over the 8-month period from 

May through December. 
 

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The sand objective is to annually deliver one million tons (0.9 million Mg) of sand to the 

Colorado River that would be available for transport in the river up to one month prior to 

the release of beach-building flows from Glen Canyon Dam. The sand augmentation 

would increase the potential for sandbar deposition throughout Marble Canyon. In order 

to prevent the augmented sand from being transported past Marble Canyon prior to 

beach-building flow, the sand would have to be accumulated and stored in or near the 

river channel during the months prior to the release of the beach-building flow. 

Together, these objectives would require that the Grand Canyon annually receive 

3.8 million tons (3.4 million Mg) of silt and clay (over the period May through 

December) and 1 million tons (0.9 million Mg) of sand prior to the beach/habitat-building 

flow. The total annual sediment supply requirement would be 4.8 million tons 

(4.3 million Mg). A portion of this sediment load could come from the Paria River, but 

sediment augmentation would still be required in most years to meet these two objectives. 

1.3 Previous Investigations 

Sediment augmentation to the Colorado River below Glen Canyon Dam was considered 

as part of the “Operation of Glen Canyon Dam Environmental Impact Statement” (U.S. 

Department of the Interior, Bureau of Reclamation, 1995). Sediment augmentation was 

included as part of the Run-of-the-River Alternative that was considered, but eliminated 

from detailed study. The environmental impact statement (EIS) concluded that sediment 

augmentation would require data collection, research and analysis, a separate EIS on 

alternative augmentations systems, and that a sediment augmentation system would take 

a decade or more to implement. Therefore, the EIS focused on dam operation 

alternatives that could be implemented right away. The EIS concluded that sediment 

augmentation could be considered at a later time. 
 

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2.0 Alternative Sediment Augmentation Systems 

A reasonable range of alternative sediment augmentation alternatives was formulated and 

evaluated for technical feasibility and cost. Attempts were made to make each alternative 

as viable as possible. However, some options were eliminated from additional 

consideration. Attempts were also made to formulate alternatives in a way that eliminate 

or reduce environmental impacts. 

Alternative sediment augmentation systems can be divided into components: 

• Sediment source areas 

• Sediment delivery locations 

• Sediment collection methods 

• Sediment delivery methods and alignments 

• Sand storage areas 

Alternatives were evaluated for each component. The choice of the sediment source area 

and the delivery location helped to determine the requirements of the remaining 

components. A summary list of each component, and the alternatives considered, are 

presented in table 1. The alternative components that were considered technically 

feasible, and considered in some detail, are listed in a bold font. Alternative components 

that may be technically feasible, but were not considered in detail because they were 

judged to be more expensive, are listed in a normal font. Other alternative components 

that were considered to be technically or logistically infeasible are presented with a gray 

shading. 
 

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Table 1. Alternative sediment augmentation features. 

Alternative Sediment 

Sources 

Lake Powell 

• Colorado River data near Hite 

Crossing, Utah 

• San Juan River 

• Dirty Devil River 

• Escalante River 

• Navajo Canyon

Lake Mead Terrestrial Site 

Alternative Sediment 

Delivery Locations 

Directly below 

Glen Canyon 

Dam 

Near Lees Ferry Other locations 

in Glen Canyon 

Paria River 

Alternative Sediment 

Collection Methods 

Clamshell dredge Hydraulic dredge Other dredges 

Slurry pipeline submerged within 

Lake Powell to Antelope Point then 

overland to below Glen Canyon Dam

Barge transport across Lake 

Powell to Antelope Point then 

truck transport to either below 

Glen Canyon Dam or Lees Ferry

Alternative Sediment 

Conveyance Methods 

and alignments from 

Navajo Canyon Slurry pipeline submerged within 

Lake Powell to Antelope Point then 

overland to Lees Ferry

Slurry pipeline overland from 

Navajo Canyon to either below 

Glen Canyon Dam or Lees Ferry

Alternative Sand 

Storage Areas 

Colorado River in Glen Canyon Terrestrial site near Lees Ferry

2.1 Alternative Sediment Sources 

Alternative sediment sources include Lake Powell Deltas, the Lake Mead Delta 

(downstream from Grand Canyon), and terrestrial sites in the region between Glen 

Canyon Dam and Lees Ferry. 

Lake Powell deltas are the preferred source of sediment because this reservoir sediment 

otherwise would have been transported through the Grand Canyon under natural 

conditions. Lake Powell contains a large volume of reservoir sediment and this volume 

continues to grow each year and gradually shortens the life of the reservoir. The 

sediments in Lake Powell generally tend to be sorted by grain size with sands 

concentrating in the reservoir deltas and fine sediment depositing farther downstream in 

deeper areas along the lake bed. Fluctuations in reservoir inflow and lake level result in 

layers of varying sediment size, so the reservoir sediments are not completely sorted. 

The Lake Mead delta contains a large volume of sediment that already came through the 

Grand Canyon. The recycling of Lake Mead sediment through Grand Canyon would not 

affect the long-term sedimentation rates in Lake Mead. However, the long distances and 
 

8

elevations over which the sediment would have to be delivered make this alternative 

source area more expensive than sources within Lake Powell. 

Sediments could be mined from land areas that are closer to the Colorado River, in the 

reach between Glen Canyon Dam and Lees Ferry, than sources in Lake Powell. 

However, the mining of sediment from terrestrial sources would not be sustainable over 

the long term. In addition, mining operations would have another set of environmental 

impacts. All of the nearby land is part of the Navajo Indian Reservation or Federally 

protected parks or wilderness. 

The areas of Lake Powell that are believed to contain sufficiently large volumes of 

sediment to augment the Colorado River in Grand Canyon are shown in figure 3 and 

table 2. The largest delta volume is the Colorado River delta near Hite Crossing, Utah, 

followed by the San Juan delta. The Navajo Canyon delta is the closest to Glen Canyon 

Dam, followed by the Escalante River delta, San Juan River delta, Dirty Devil River 

delta, and the Colorado River delta. 

Figure 3. Lake Powell and delta locations. 

Lake Powell Deltas 

Colorado River 

near Hite 

Crossing 

San Juan River 

Dirty Devil 

River 

Escalante River 

Navajo Canyon

Glen Canyon 

Dam 
 

9

Table 2. Lake Powell 1986 delta distances and sedimentation volumes 

(Ferrari, 1988 and Ferrari, Bureau of Reclamation, written communication, 2006). 

Distance from Glen 

Canyon Dam Sedimentation Volume 

Lake Powell Delta miles km Acre-feet m3

Colorado River near Hite, Utah 170 270 472,000 580,000,000

Dirty Devil River 160 260 22,000 27,000,000

San Juan delta 120 190 281,000 350,000,000

Escalante River 99 160 23,000 28,000,000

Navajo Canyon 33 52 29,000 36,000,000

2.1.1 Navajo Canyon 

The sediments of Navajo Canyon are about 70 feet thick at the canyon mouth and about 

60 feet thick at the upstream delta. The sediments at the mouth are submerged by 340 to 

480 feet (110 to 150 m) of water and are likely silt or clay in size. At a full reservoir pool 

elevation of 3700 feet (1128 m), the reservoir portion of Navajo Canyon is 22 miles 

(35 km) long (see figure 4). At a distance of 11 miles (18 km) from the canyon mouth, 

the delta surface consists of fine sand with silt. 

A sample was obtained from the delta surface, at about river mile 11 (18 km) during a 

reconnaissance field trip in November 2004 (see figure 5). The laboratory results from 

this sample are summarized below. More detailed results are presented in Appendix A. 

• 57 percent silt and clay 

• 43 percent sand 

o 30 percent very fine sand 

o 13 percent medium sand 

• Angular quartz particles have high potential for abrasion of pipes, valves, and 

pumps 

• The sample was analyzed for 39 elements, but no contaminants were found. 
 

10

3110.0

3210.0

3310.0

3410.0

3510.0

3610.0

3710.0

0.00 5.00 10.00 15.00 20.00 25.00

Distance (miles)

Elevation (feet)

2004

1986

Original

R- 421

R- 422

R- 424

R- 425

R- 427

R- 429

R- 430

Figure 4. Longitudinal sediment profiles of Navajo Canyon. 

Figure 5. Navajo Canyon delta surface near river mile 11 (18 km) on 

November 3, 2004. 
 

11

The sediment in Navajo Canyon is the closest sediment to Glen Canyon Dam that is 

believed to be sufficiently large to support a sediment augmentation program for Grand 

Canyon. Therefore, the cost of delivering reservoir sediment from Navajo Canyon is 

expected to be significantly less than any other viable source within Lake Powell. 

The sedimentation volume of Navajo Canyon is estimated to be a maximum of 

30,000 acre-feet (37 million m3

), based on the Lake Powell surveys of 1986 (Ferrari, 

1988) and 2004 (Ferrari, Bureau of Reclamation, written communication, 2006). 

Assuming a unit weight of 70 lbs/ft3 (1.1 g/cm3), the sediment mass is estimated to be a 

maximum of 40 million tons (36 million Mg), with an average annual sedimentation rate 

of 1 million tons per year (0.9 million Mg/yr). As previously stated, the sediment sample 

from the delta surface near the receded lake elevation was 57 percent silt and clay and 

43 percent sand. An assumption is made that delta sediments farther upstream will 

contain a significantly higher percentage of sand while sediments that are father 

downstream will contain a significantly higher percentage of silt or clay. This 

assumption would have to be verified in subsequent investigations. 

Antelope Canyon may also be another significant sediment source that is 5 miles (8 Km) 

closer to Glen Canyon Dam. The present sediment volume from Antelope Canyon is 

unknown. The drainage area of Navajo Canyon (760 mi2

 or 2,000 km2) is 4.5 times 

larger than the drainage area of Antelope Canyon (170 mi2 or 450 km2). The larger 

drainage area of Navajo Canyon would be expected to have a greater sediment yield than 

the yield from Antelope Canyon. In addition, the longitudinal profiles of Lake Powell, 

measured in 1986, 2001, 2004, and 2005, all indicate the presence of a sediment deposit 

that extends 3 to 4 miles (5 to 6 Km) from the mouth of Navajo Canyon, along the old 

Colorado River channel submerged by Lake Powell (see figure 6). A similar such 

deposit is not evident in the longitudinal profiles at the mouth of Antelope Canyon. 

However, a submarine fan at the mouth of Antelope Canyon is evident in detailed 

bathymetry plots measured in June 2005 (see figure 7). This submerged fan extends 

longitudinally for a distance of one or two canyon widths (1,000 to 2,000 feet or 300 to 

600 m). 
 

12

Navajo 

Canyon

Antelope 

Canyon

Figure 6. Longitudinal bottom profiles of Lake Powell (L. Pratson, 

Duke University, written communication, October 3, 2006). 

The annual sedimentation rates in Navajo Canyon are probably not be large enough to 

indefinitely sustain a sediment augmentation program for Grand Canyon providing 

3.8 million tons (3.4 million Mg) annually (see figure 8). However, the existing 

sedimentation volume and the future rate of sedimentation likely would sustain a 

sediment augmentation program for one or two decades, assuming that Paria River 

supplies sediment, at an average annual rate of 1 million tons per year (0.9 million 

Mg/yr), to partially meet the objectives described in section 1.2. The removal of 

reservoir sediment from Navajo Canyon would not preclude the future removal of 

reservoir sediment from more distant areas of Lake Powell. Therefore, the Navajo 

Canyon area of Lake Powell is the only sediment source considered in detail for this 

investigation. 
 

13

Figure 7. Detailed bathymetry at the mouth of Antelope Canyon shows a 

summarine fan deposit in the old Colorado River channel that extends 

longitudinally for a distance of one or two Colorado River canyon widths 

(L. Pratson, written communication, December 1, 2006). 

0

20

40

60

80

100

120

140

160

180

200

1,000,000 1,500,000 2,000,000 2,500,000 3,000,000 3,500,000 4,000,000

Annual Sediment Augmentation Rate (tons per year)

Life Expectancy (years)

Figure 8. Life expectancy of the Navajo Canyon sediment source as a function of 

the annual sediment augmentation rate. 
 

14

2.1.2 Other Sediment Source Areas Not Considered in Detail 

The following sediment source areas of Lake Powell were not considered in detail for this 

study, but these areas may warrant additional study in the future: 

• San Juan River delta 

• Colorado River delta near Hite, Utah 

• Dirty Devil River delta 

• Escalante River delta 

The Lake Mead delta also was not considered in detail because the long distances and 

elevations over which the sediment would have to be delivered make this alternative 

source area more expensive than sources within Lake Powell. 

2.1.3 Sediment Source Areas Eliminated From Consideration 

Wahweap Bay area of Lake Powell is very close to Glen Canyon Dam, there is good road 

access, and electrical power is readily available. However, the small sediment volume 

and large percentage of gravel make this an unsuitable source for the purposes identified 

in section 1.2. 

Sediments could be mined from land areas that are closer to the Colorado River between 

Glen Canyon Dam and Lees Ferry, Arizona than the sediment source areas within Lake 

Powell, but such sources would not be sustainable over the long term. In addition, 

mining operations would have another set of environmental impacts. All of the nearby 

land is part of the Navajo Indian Reservation or Federally protected parks or wilderness. 

Some people have suggested that Paria River sediment loads be somehow increased or 

that a dam be built across the Paria River to store and regulate future sediment loads. 

The Paria River enters the Colorado River 16 miles (26 km) downstream from Glen 

Canyon and is now the second largest source of sediment to the Grand Canyon (Wright et 

al, 2005). The Paria River naturally supplies an average annual sediment load of 

3.0 million tons per year (2.7 Mg/yr) (Andrews, 1991). Any scheme to increase Paria 

River sediment loads would require that additional water be diverted into the Paria River 

basin. Additional water is not likely available for such purposes. Once sediments are 

eroded from the landscape, they cannot be eroded from the same location again. 

Increases in sediment loads over the short term would reduce sediment loads in subsequent years. Therefore, a sustained increase in Paria River sediment loads is not possible. 

A dam and reservoir across the Paria River to regulate sediment loads is not technically 

feasible without a great deal of mechanical intervention. The reservoir sediment-trap 

efficiency decreases with increases in reservoir flow velocity and increases with sediment 

particle size (Strand and Pemberton, 1983). Sand and coarser sized sediments would tend 

to deposit in a reservoir pool while a large portion of the finer silts and clays would be 
 

15

transported through a sediment retention reservoir. The reservoir sediment-trap 

efficiency would reduce over time as the reservoir filled with sediment so that inflowing 

sediments would be transported through the reservoir. Sand sized sediments would 

deposit as a delta across the entire width of the reservoir while fine sediment would tend 

to be transported through the reservoir. If the reservoir were drawn down to release 

stored sediments, river flows would only erode a narrow channel through the reservoir 

sediments and a great majority of the reservoir sediments could only be removed through 

mechanical intervention (Morris and Fan 1997). In addition, the Paria River is in a 

federally protected wilderness area where the construction of dams or roads would not be 

allowed, except by special act of Congress. 

2.2 Alternative Sediment Delivery Locations 

The primary delivery points considered for this study are immediately downstream from 

Glen Canyon Dam and near Lees Ferry (see figure 9). Other delivery points within the 

Glen Canyon reach were considered such as Ferry Swale Canyon and Water Holes 

Canyon. However, these other locations do not expand the range of reasonable 

alternative delivery locations bounded by Glen Canyon Dam and Lees Ferry. Sediment 

delivery near Lees Ferry would avoid many of the impacts to the trout fishery in the Glen 

Canyon reach, but at more cost than sediment delivery below Glen Canyon Dam. 

Sediment delivery immediately below Glen Canyon Dam would have the potential to 

restore a portion of the pre-dam sediment transport conditions in the reach between Glen 

Canyon Dam and Lees Ferry. However, sediment delivered to the Glen Canyon reach 

may impact the trout fishery and the aquatic food base. 
 

16

Figure 9. Glen Canyon reach of the Colorado River between Glen Canyon Dam and 

Lees Ferry, Arizona. 

2.2.1 Below Glen Canyon Dam or near Lees Ferry 

The alternative sediment delivery locations are summarized below: 

• Below Glen Canyon Dam 

o Sand: continuous year-round discharge 

o Silt and clay: continuous, seasonal discharge 

• Lees Ferry 

o Sand: stock pile and discharge before beach-building flow 

o Silt and clay: continuous, seasonal discharge 

For the purposes of this study, the following delivery requirements are assumed. These 

assumptions will have to be further evaluated and refined by subsequent studies. 

• Delivery of 1 million tons (0.9 million Mg) of sand per year, which would be 

available for transport by the Colorado River in Grand Canyon a month prior to, 

and during, special beach-building flows released from Glen Canyon Dam. 
 

17

• Delivery of enough silt or clay-sized material to continuously increase the 

suspended sediment concentration by 500 ppm during the period May through 

December of each year. 

Although fine sediment needs to continuously discharge into the Colorado River, the 

sand must be stored somewhere prior to the beach-building flow. If the sand were 

delivered too early, then there is concern that it would be transported past Marble Canyon 

prior to the beach-building flow (Rubin et al, 2002). If sand were first delivered to the 

Colorado River at the beginning of the beach-building flow, then the discharge wave 

would be expected to travel through Marble Canyon faster than the sand augmentation 

(Rubin et al, 2002). 

The slope of the Colorado River downstream from Lees Ferry is significantly steeper 

than in the Glen Canyon reach upstream from Lees Ferry. Sand delivered to the 

Colorado River just downstream from Lees Ferry is expected to be transported 

downstream through Marble Canyon in a matter of months (Rubin et al, 2002, Wright et 

al, 2005, and Topping et al, 2000a and 2000b). However, sand delivered to the Glen 

Canyon reach, just below Glen Canyon Dam, is expected to be transported at a much 

slower rate with a significant portion being stored in pools (Grams et al, in press). 

Sand delivered to Lees Ferry would have to be stored in close proximity to the Colorado 

River. No sand storage areas exist immediately below Glen Canyon Dam, but sand 

introduced into the Colorado River below the dam may be deposited in deep pools of the 

Glen Canyon reach and remain there until periods of high flow. A very short-duration 

high flow, but less than the magnitude of the beach-building flow, could be released from 

the dam a month prior to the beach-building flow to initiate the sand transport to Marble 

Canyon. Existing sandbars might be scoured if the magnitude of the pre-high flow 

release were too high. A high-flow release with a few hours duration would likely 

attenuate rapidly as the discharge wave traveled downstream and thus reduce its sediment 

transport capacity past the Glen Canyon Reach. Once the sand is transported into the 

Marble Canyon reach, the beach-building flow could be released from Glen Canyon 

Dam. These assumptions need to be verified in subsequent studies. 

Sands and fine sediments could be delivered to the Colorado River below Glen Canyon 

Dam through either slurry pipelines or by trucks. The slurry pipelines would join and 

enter Glen Canyon though a single inclined shaft, excavated by directional drilling from 

the canyon plateau. 

The inclined shaft would have a high head at the discharge point and would require a 

control valve and concrete structure located at the approximate level of the river. The 

energy from these pipelines would be dissipated by the discharge of the slurry into a pool 

area of the Colorado River. 
 

18

2.2.2 Sediment Delivery Points Eliminated from Consideration 

The delivery of sediment to the Paria River canyon was eliminated from further 

consideration because there would no means of transporting the augmented sediments to 

the Colorado River in a timeframe that would meet management objectives. Augmented 

sediments would likely form a deposit that would only be transported episodically during 

flash floods. 

The Paria River delivery point was also eliminated because of the Wilderness status for 

the river canyon. 

2.3 Alternative Sediment Collection Methods 

Sediment would be dredged from Lake Powell using two separate dredges. One dredge 

would be positioned in the downstream reaches of Navajo Canyon where the lake depths 

are deep and the bottom is believed to be covered with fine sediments. The second 

dredge would be placed farther upstream in Navajo Canyon where the lake surface 

intersects the delta and the sediments are believed to be primarily sand. This would 

require that sands would have to be transported farther than the fine sediments. 

Each of the two dredges would require at least two to three personnel which includes a 

qualified dredge operator and a mechanic. This is required for both safety and to address 

general maintenance of the dredges. The dredges would be operated 24 hours a day (with 

short down times for maintenance and dredge positioning), so operators would have to 

work in shifts. A boat would be required to transport the various crews to and from the 

dredges. 

The dredge excavating sands would be operated approximately year round to accumulate 

one million tons (0.9 million Mg) of sand. The dredge collecting the fine sediments 

would be operated from May through December of each year. 

There are many types of dredges that can be used to excavate sediment (see appendix B): 

• Suction Dredges 

• Dragline Dredges 

• Clamshell Dredges 

• Auger Dredges 

• Cutter Dredges 

• Ladder-Bucket Dredges 

• Hopper Dredges 

• Rotary or Bucket Head Cutter Dredges 

• Excavator or Backhoe Dredges 

Due to the range of possible water depths, clamshell style dredges which have an 

excavating depth range of up to 300 feet (90 m) would be used. The clamshell dredges 
 

19

have two buckets (with a capacity of 13 yd3 or 9.9 m3), hinged together that close around 

the sediment and are then lifted back to the surface by a cable hoist system (see figure 10) 

The sediment is then dumped onto a mechanical separator that removes any rocks or 

woody debris from the dredged material. The sediment can then be either conveyed to a 

barge for transport or moved into a mixer where water is added by a fresh water pump to 

create the desired solids concentration for the slurry pipeline. Slurry pumps can then 

discharge this mixture into the slurry pipelines. 

Figure 10. Clamshell dredge excavating sediment. 

For every one million tons (0.9 million Mg) of sand that is dredged per year, 4,000 tons 

(3,600 Mg) of sand would be dredged per day, assuming 250 working days per year. For 

every one million tons (0.9 million Mg) of fine sediment that is dredged per year, 

6,000 tons (5,400 Mg) of fine sediments would be dredged per day, assuming 166 

working days per year. The expected life of the sediment collection system may be about 

a decade. However, the expected life has not been precisely determined for this study 

and would have to be determined at the next (feasibility) level of investigation. 

2.4 Alternative Sediment Conveyance Methods and Alignments 

The alternative sediment conveyance methods include sediment slurry pipelines, barges, 

and trucks. The sediment slurry pipeline was found to be the only viable method for 

conveying the large quantities of sediment from Lake Powell to the Colorado River (see 

table 3). Barges across Lake Powell are not a feasible method of sediment transport 

because of the excessive number of required barge trips (see section 2.4.2.1). Trucks are 

also not feasible because of the excessive number of required trips on the highways (see 

section 2.4.2.2). 
 

20

Table 3. Feasibility summary of sediment delivery methods. 

Conveyance Alternative 

from Navajo Canyon Feasibility 

Barge sediment across Lake 

Powell then convey overland 

by truck to the delivery point 

Technically infeasible because of the large impacts 

to recreation use and aesthetics on portions of Lake 

Powell and the excessive number of trucks required 

on the highways. 

Slurry pipeline within Lake 

Powell and overland slurry 

pipelines along existing roads 

to delivery points 

Technically feasible at low enough concentrations 

(< 20 percent, by weight). At higher concentrations, 

the pipelines may clog during power outages when 

flow velocities would be reduced to zero. 

Overland slurry pipelines out 

of Navajo Canyon and then 

continuing along existing 

roads to the delivery point 

Technically infeasible because the access is too 

difficult, the head is too high, and because a floating 

pipeline or barges would still be required within 

Navajo Canyon. 

Alternative slurry pipeline alignments were considered from the sediment source area of 

Navajo Canyon and to the Colorado River delivery points. The following criteria were 

used to evaluate alternative slurry pipeline alignments: 

• The slurry pipelines would have to exit Lake Powell at a point where the 

topography would not be too steep to build a pumping plant at the lake shoreline 

elevation. The first land-based pumping plant would have to be constructed just 

above elevation 3700 feet (1128 m), the full pool elevation of Lake Powell. This 

is because the lake elevation could decrease by 150 feet (46 m). Road access to 

the pipeline and pumping plant also would have to be feasible. 

• Permission would have to be granted for the pipeline alignment. Alignments 

across Federal lands or along existing highway right-of-ways would be most 

feasible. 

• Significant impacts to cultural and natural resources (including aesthetics) should 

be avoided where possible. 

Overland routes out of Navajo Canyon were eliminated from additional consideration 

because access is too difficult, the head to pump a sediment slurry is too high (1,000 feet 

or 300 m), and because a floating pipeline or barges would still be required in Navajo 

Canyon. In addition, any overland routes out of Navajo Canyon would have significant 

impacts to cultural and natural resources within the Navajo Nation. 

The viable pipeline-alignment alternatives include submerged slurry pipelines across 

Lake Powell to Antelope Point, then overland to either below Glen Canyon Dam or Lees 

Ferry (see figure 11). A plan-view map and longitudinal profile of the pipeline alignment 

from Navajo Canyon to below Glen Canyon Dam are presented in figures 12 and 13. A 

plan-view map and longitudinal profile of the pipeline alignment from Navajo Canyon to 

Lees Ferry are presented in figures 14 and 15. 
 

21

Figure 11. Alternative sediment slurry pipeline routes from Navajo Canyon to 

below Glen Canyon Dam and to Lees Ferry. 
 

22

PP3

PP5

PP4

PP6

Figure 12. Plan-view map of the pipeline alignment from Navajo Canyon to 

Glen Canyon Dam (add 3.5 miles or 5.6 km to distances to determine the 

total pipeline length). 

Figure 13. Longitudinal profile of the pipeline alignment from Navajo Canyon to 

Glen Canyon Dam (add 3.5 miles or 5.6 km to determine total pipeline length). 

4000 ft = 1219 m

Full Lake elevation at 3700 ft = 1128 m

4300 ft = 1311 m

O mi 5 mi 10 mi 15 mi 20 mi 25 mi

O km 8 km 16 km 24 km 32 km 40 km

Sediment Slurry Pipeline Distance

Elevation
 

23

Figure 14. Plan-view map of the pipeline alignment from Navajo Canyon to Lees 

Ferry (add 3.5 miles or 5.6 km to distances to determine the total pipeline length). 
 

24

6200 ft = 1890 m

5800 ft = 1768 m

5200 ft = 1585 m

4600 ft = 1402 m

4000 ft = 1219 m

Full Lake elevation at 3700 ft = 1128 m

O mi 5 mi 10 mi 15 mi 20 mi 25 mi 30 mi 35 mi 40 mi 45 mi 50 mi 55 mi 60 mi 65 mi

O km 8 km 16 km 24 km 32 km 40 km 48 km 56 km 64 km 72 km 80 km 89 km 97 km 105 km

Sediment Slurry Pipeline Distance

Elevation

Figure 15. Longitudinal profile of the pipeline alignment from Navajo Canyon to 

Lees Ferry (add 3.5 mi or 5.6 km to distances to determine the total pipeline length). 

Antelope Point is suggested as the location to exit the slurry pipelines from Lake Powell 

because of the gently sloping topography and the existing road access. The option of 

aligning the submerged pipelines all the way to Glen Canyon Dam was not considered 

feasible. This is because there is no place to construct a pumping plant near the dam at 

the full pool lake elevation and the near vertical canyon walls are still 60 feet (20 m) 

above the full pool elevation. If the lake surface elevation were to drop 150 feet (46 m), 

the last floating pumping plant would have to pump the slurries the elevation of the 

receded reservoir plus any additional elevation rise to the next pumping plant on the 

canyon rim. The total elevation rise could be as much as 210 feet (64 m) at Glen Canyon 

Dam and may not be possible. 

The option of routing the pipelines through the dam also was considered infeasible 

because of the safety concerns about drilling a hole through the dam and the long-term 

abrasion of the sediment slurry pipelines. In addition, there are logistical problems of 

drilling holes through the dam at depths as much as 160 ft (49 m) within Lake Powell. 

The actual depth would depend on the lake elevation at the time of construction. 

Although the lake might be drawn down 150 ft (46 m) during the time of construction, 

the lake might be full when the slurry pipelines need to b replaced. Even if the slurry 

pipelines could be routed through Glen Canyon Dam, this would not facilitate the alternative of delivering sediment to Lees Ferry. A slurry pipeline through the 16 mi (26 km) 

reach of Glen Canyon is not feasible because there is no road access from which to 

construct the pipeline, there is no room for the pipeline, and there would be tremendous 

construction-related impacts to cultural and natural resources in Glen Canyon. 
 

25

Exiting the slurry pipelines from Lake Powell at a point about 1 mile (1.6 km) upstream 

from Glen Canyon Dam may be a feasible option because the topography is not too steep 

to construct a pumping plant and new spur road. Another option may be to route 

sediment slurry pipelines up the upstream face of Glen Canyon Dam, over the dam 

adjacent to one of the abutments, then down the downstream face of the dam and 

terminating at the base of the dam. This option would not work for the alternative to 

deliver sediment to Lees Ferry. The options of exiting the lake 1 mile (1.6 km) upstream 

from Glen Canyon Dam or over the dam may be a less expensive than exiting the lake at 

Antelope Point and they could be considered at the next (feasibility) level of 

investigation. 

The alternative pipeline alignment to Lees Ferry was assumed to follow the existing 

right-of-way for U.S. Highway 89. This alignment tends to avoid adverse impacts from 

construction activities to cultural and natural resources within the Navajo Nation or the 

Glen Canyon National Recreation Area. Other shorter alignment options may exist, at 

potentially less cost, but only if the construction and operations impacts can be tolerated. 

2.4.1 Slurry Pipelines 

Sediment slurry pipelines can efficiently transport large quantities of sediment over long 

distances. The required water volumes are small (0.2 percent) compared to the flow of 

the Colorado River. All of the water released through the slurry pipelines would be 

counted as part of the Upper Basin deliveries to the Lower Basin. Pumping stations 

would be required to convey the sediment along both the water and land portions of the 

pipeline routes. A summary of pipeline lengths and pumping plants is presented in table 

4. 

Table 4. Summary of alternative sediment slurry pipeline alignments. 

Submerged 

Pipeline Length 

Buried Pipeline 

Length 

Number of Pumping 

Plants 

Slurry Pipeline Alignment (miles) (km) (miles) (km) Floating Land-based 

Navajo Canyon to below 

Glen Canyon Dam 18 29 11 18 3 3 

Navajo Canyon to Lees 

Ferry 18 29 50 80 3 14 

Sediment mixing stations would have to be assembled for the dredging stations in Navajo 

Canyon to provide the proper sediment concentrations in the pipelines. In order to take 

advantage of the natural sorting of sediments within the reservoir, the dredging of sand 

would occur at shallower depths and farther upstream than the dredging of silt and clay. 

For the Lees Ferry alternative alignment, settling basins and sand stockpile areas would 

be required at the delivery point near Lees Ferry (see Appendix C). 
 

26

On Lake Powell, slurry pipelines would be supported by buoys and submerged to a depth 

of between 10 and 15 feet (3 to 5 m) so that the pipelines would not impede boat traffic 

or impact aesthetics. The pipelines would raise and lower with the water surface elevation of Lake Powell. The pipelines would be flexible and aligned along the centerline of 

the submerged river channel so that the pipelines would not come in contact with, and be 

damaged by, the canyon walls during lake-level fluctuations. The buoys would be spaced 

about every 500 feet (150 m) and would divide boat navigation into upstream and downstream lanes of traffic. However, boats would be able to cross over the pipelines between 

buoys. Anchors for the buoys would rest on the existing lakebed sediments so they 

would not additionally impact any cultural resources submerged within Lake Powell. 

Pulleys and counterweights would be used to maintain the required depth of 

submergence. A metal frame would be used to keep the pipelines together. A submerged 

electrical power line would be included with the pipelines to provide power for the 

pumping plants (see figure 16). The submerged power line would be protected by a thick 

casing and the surrounding pipelines. Electrical power would automatically shut off in 

the event the power line was cut or severed. 

Figure 16. Submerged sediment slurry pipelines. 

Other power sources were considered and eliminated for the floating pumping plants 

because of their infeasibility or unacceptable impacts. These other alternatives include 

the continual supply of gasoline or diesel fuel or electrical power through an overhead 

power line. 
 

27

• The fuel requirements for gas or diesel engines could be quite significant for all 

the floating pumping plants. The use of gas or diesel engines to power the pumps 

would create local impacts related to noise and air quality. There would also be 

some risk of fuel spills in Lake Powell. 

• The construction of an overhead power line to the floating pumping plants would 

impact cultural, natural, and aesthetic resources along the shoreline of Lake 

Powell. Electric pumps would be quieter than gas or diesel motors and avoid the 

local impacts to air quality and avoid the risk of fuel spills. However, no scheme 

was identified to connect a stationary overhead power line to the floating pumping 

plants on a fluctuating lake surface. 

A submerged power line (attached to the slurry pipeline) would avoid the impacts to 

cultural and aesthetic resources along the shoreline of Lake Powell, but there would still 

be the aesthetic impacts from the floating pumping stations. 

Sand would be conveyed through two 12-inch (30 cm) diameter high-density 

polyethylene (HDPE) pipelines. Because the sand pipelines would be used year round, a 

third 12-inch (30 cm) diameter HDPE pipeline would be provided as a backup to be used 

during maintenance, repair, or replacement of the pipelines. The flow rate through these 

pipelines would be 4.1 ft3

/s (0.12 m3/s) with a sand concentration of 20 percent, by 

weight. The annual water volume would be 2,900 acre-feet per year (3.6 million m3

/yr). 

Fine sediment would be conveyed through three 24-inch (61 cm) diameter HDPE 

pipelines. No backup fine-sediment pipeline would be provided because the pipelines 

would be operated eight months per year. The flow rate through the fine sediment 

pipelines would be 23 ft3/s (0.64 m3/s) with a fine sediment concentration of 20 percent, 

by weight. The annual water volume would be 11,000 acre-feet per year (14 million 

m3/yr). The combined annual flow volume through all pipelines would be 14,000 acrefeet per year (17 million m3

/yr), which is 0.17 percent of the minimum annual flow 

release from Glen Canyon Dam (8.23 million acre feet per year or 10 billion m3

 per year). 

Any water released through the sediment slurry pipelines would be counted as deliveries 

from the Upper Basin to the Lower Basin. The mass and volumetric flow rates through 

the slurry pipelines are presented in table 5. 

The service life of a sediment slurry pipeline, made of HDPE, is expected to exceed 

20 years. With adequate particulate suspension, HDPE pipe has an extremely high 

resistance to abrasion from slurries. In some applications, HDPE pipe has outlasted steel 

pipe by as much as a factor of 4 (http://www.kwhpipe.ca/know_faqs.asp#10). Slurry 

TransportDriscoPlexTM piping has demonstrated superiority to other types of piping 

where corrosion and erosion problems exist. Design information on slurry piping design, 

velocity and particle size can be found in the Performance Pipe Engineering Manual. 

(www.performancepipe.com). 
 

28

Table 5. Sediment slurry pipeline mass and volumentric flow rates. 

Colorado River below Glen Canyon Dam

8,230,000 acre-ft/yr = 1.015E+10 m3/yr Minimum annual flow release from Glen 

Canyon Dam 

11,360 ft3/s = 321.7 m3/s Average annual flow release from Glen 

Canyon Dam 

708,873 lbs/s = 321,543 Kg/s Mass flow rate of water 

500 ppm = 500 ppm Target suspended sediment concentration 

(May 1 through December 31) 

354 lbs/s = 161 Kg/s Suspended sediment mass flow rate 

 

15,312 tons/day = 13,891 Mg/day Suspended sediment mass flow rate 

245 days/yr = 245 days/yr Fine sediment delivery period (May 1 

through December 31) 

3,751,355 tons/yr = 3,403,207 Mg/yr Annual sediment delivery 

 

Fine Sediment Slurry Pipeline

1,772 lbs/s = 804 Kg/s Sediment slurry mass flow rate (water, clay, 

and silt) 

20% 20% Sediment slurry pipeline concentration, by 

weight 

354 lbs/s = 161 Kg/s Sediment mass flow rate 

1,418 lbs/s = 643 Kg/s Water mass flow rate 

22.7 ft3/s = 0.643 m3/s Water volumetric flow rate 

24 inch = 61 cm Pipeline diameter 

3 3 Number of operational pipes 

7.57 ft3/s = 0.214 m3/s Water volumetric flow rate per pipe 

2.41 ft/s = 0.735 m/s Average water velocity per pipe 

 

Sand Slurry Pipeline 

1,000,000 tons/yr = 907,194 Mg/yr Target annual sand delivery rate 

365 days/yr = 365 days/yr Delivery period 

2,740 tons/day = 2,485 Mg/day Average daily sand delivery rate 

63 lbs/s = 29 Kg/s Sediment mass flow rate 

20% 20% Sediment slurry pipeline concentration, by 

weight 

317 lbs/s 144 Kg/s Sediment slurry mass flow rate 

254 lbs/s 115 Kg/s Water mass flow rate 

4.07 ft3/s = 0.115 m3/s Water volumetric flow rate 

12 inch = 30 cm Pipeline diameter 

2 2 Number of operational pipes 

1 1 Spare pipeline 

2.03 ft3/s = 0.058 m3/s Water volumetric flow rate per pipe 

2.59 ft/s = 0.789 m/s Average water velocity per pipe 
 

29

The pipelines for silt and clay are expected to experience little wear because of the low 

kinetic energy with which fine particles strike the pipe surface. The transport of silt and 

clay at concentrations up to 35 percent by volume may be possible, but there could be 

clogging problems during power outages when the flow velocity would become zero and 

sediment particles would settle within the pipes. 

Sand is expected to have greater wear on pipelines than silt or clay. The polyurethane 

lining of the sand slurry pipelines and pumps may extend their life expectancy to 20 or 

more years. Wear of the pipeline surface is proportional to the concentration and, in 

addition to clogging, is another reason to keep concentrations less than 20 percent by 

weight. The flow velocity in the sand slurry pipelines may be below the critical 

sedimentation velocity for a 12-inch (30-cm) diameter pipe, so a smaller diameter 

pipeline may have to be used. However, the assumption of a 12-inch (30-cm) diameter 

pipe would provide for a higher cost estimate. 

On Lake Powell, pumping plants would float on modular barges that would also raise and 

lower with lake levels (see figure 17). The pumping plants would be covered by a building to protect the plants from waves and the elements and to minimize noise on the lake. 

The buildings could be made to resemble house boats or painted to blend in with the 

canyon walls. Floating pumping plants were considered rather than submerged pumps 

because of the need for maintenance access. Submerged plants could be considered, but 

a barge may still be needed as a maintenance platform and to support the weight of the 

submerged pumps. During periods of lake recession, the floating pumping plants may 

have to be moved to deeper areas of the lake. A floating pumping plant would be less 

likely to get stuck in the reservoir sediment than a submerged pumping plant. 

Figure 17. Pumping plants on Lake Powell would be floated on modular barges 

while pumping plants on land would be contained within permanent buildings.

Land-based pumping plants would be protected by permanent buildings. Both the 

floating and land-based pumping plants would be about 30 feet (9 m) wide, 60 feet 

(18 m) long, and 10 feet (3 m) high. Pressure reduction stations would be required along 

the descending segment of the pipelines to Lees Ferry. 
 

30

The submerged pipelines would require some sort of shoreline anchors where the 

pipelines exit the lake. The pipeline anchors would have to protect the pipelines at a 

range of lake elevations (3550 to 3700 feet) to protect them from movement against the 

bedrock caused by wave action. This would be accomplished by submerging the pipelines to a depth below the rim of the submerged Colorado River canyon and exiting the 

canyon rim through an inclined shaft drilled through the bedrock. The inclined shaft 

would be excavated by directional drilling over a vertical distance of 30 to 50 feet (9 to 

12 meters). Past the inclined shaft, the pipelines would be buried in a trench excavated in 

the sandstone bedrock. If construction occurred during times of high lake elevation, then 

the anchor blocks would be attached to the pipelines and it would be submerged on the 

bedrock of the lake bottom. Later, pipelines could be buried during the lake recession. 

The drilling of the inclined shaft and the cut and cover through the bedrock was assumed 

to be the more expensive option, therefore, was included in the cost estimate. 

On land, the pipelines would be buried along the right-of-ways of existing roads and 

highways. 

The alternatives that deliver sand, silt, or clay to below Glen Canyon Dam (Options 1, 3, 

and 5) would require drilling an inclined shaft through 860 vertical feet of sandstone 

bedrock (elevations 4000 to 3140 feet). All the pipelines could be fed into the same 

shaft, but the shaft would have to be lined to slow abrasion. The lining could be replaced 

about once every decade. 

The alternatives that deliver silt and clay to Lees Ferry (Options 2, 3, and 4) would 

require drilling an inclined shaft through 200 vertical feet of sandstone bedrock at the 

canyon rim. All the fine-sediment pipelines and water from the sand pipelines could be 

fed into the same shaft, but the shaft would have to be lined to slow abrasion. Sand 

would be settled and stock piled along the canyon rim. 

2.4.2 Sediment Conveyance Methods Eliminated from Consideration 

The sediment conveyance alternatives of barge transport on Lake Powell and overland 

transport by truck were found to be infeasible and eliminated from additional 

consideration. 

2.4.2.1 Barge Transport on Lake Powell 

This alternative would attempt to barge the sediments from the dredging sites to Antelope 

Point, near Glen Canyon Dam. From there the sediments would be transported by trucks 

or through slurry pipelines to the Colorado River, either below Glen Canyon Dam or to 

Lees Ferry. 

Barges on Lake Powell would have to navigate the narrow canyons of the reservoir and 

be able to cope with heavy recreation boat traffic during summer. Assuming that each 

barge could transport 110 tons (100 Mg) of sand, 9,100 barge loads would be required to 
 

31

deliver 1 million tons (0.9 million Mg) of sediment per year. The delivery of 1 million 

tons (0.9 million Mg) of sand would require 36 barge loads per day, assuming 250 

working days per year. The delivery of 3.8 million tons (3.4 million Mg) of fine 

sediment would require 206 barge loads per day, assuming 166 working days per year. A 

maximum number of 242 barge loads per day would be required to meet the delivery 

targets for both sand and fine sediment. 

Barging does not appear to be a desirable option due to the following reasons: 

• The narrow winding canyons would make barge access, passage, and turn-around 

difficult. 

• Barges would be large, slow, and not very maneuverable. 

• Once the barges reach the loading and unloading points, the task of moving the 

sands or fine sediments to and from each barge could be a slow process. This 

may create a bottle neck in the barging process and may increase the number of 

barges needed. 

• A large number of personnel would be required for barge operations. Personnel 

would be needed to move the barges between the dredging sites and at the 

unloading point. Additional personnel would be needed to position and load the 

barges from the dredges and to unload the barges and then load the trucks or 

slurry pipelines. 

• The large number of barge loads would require a continuous convoy of barges 

between Navajo Canyon and Antelope Point, which may require the restriction of 

recreation boat traffic in these areas of Lake Powell. 

2.4.2.2 Overland Transport by Truck 

The concept of trucking sediments directly from the dredging sites within Navajo Canyon 

to either Lees Ferry or just below Glen Canyon Dam has been eliminated due to the 

following factors: 

• There is no road access to the Navajo Canyon dredging sites. 

• The steep canyon walls of Navajo Canyon would make road construction nearly 

impossible or very expensive due to the 1,000-foot (300-m) elevation rise from 

Lake Powell to the canyon plateau (see figure 18). The construction of a two-lane 

road would require a lot of rock blasting through the pristine canyon. A tunnel 

access roadway may need to be constructed, similar to the tunnel leading to the 

base of Glen Canyon Dam. However, a tunnel could not be constructed below a 

full lake elevation. 
 

32

• The changing level of Lake Powell would require the changing location of the 

dredges, so barges or slurry pipelines would be needed to convey sediment from 

the dredge site to a newly constructed road. 

• The roadways in the canyon and on the plateau all would be on Navajo Nation 

lands and permission to construct the roadways would be required. 

Another eliminated alternative was to transport sediment from Navajo Canyon, across 

Lake Powell by barge or slurry pipeline, to Antelope Point where trucks could then 

transport the sediments to the Colorado River below Glen Canyon Dam or near Lees 

Ferry. For the delivery point below Glen Canyon Dam, a new road access tunnel would 

have to be constructed to route trucks to the bottom of Glen Canyon. The large number 

truck loads would be in direct conflict with present traffic uses in the existing road access 

tunnel to the base of the dam. 

Figure 18. There are no roads in the remote area of Navajo Canyon where 

bedrock rises 1,000 feet (300 m) from the surface of Lake Powell. 

The road access tunnel would become a restriction for the size of trucks. Smaller single, 

rear-axle dump trucks, with a load capacity of 5 tons (5 Mg) per truck, would have to be 

used because there would not be room for large trucks to maneuver at the bottom of the 

tunnel. The annual delivery of 1 million tons (0.9 million Mg) of sand would require 

approximately 800 truck loads per day, assuming 250 working days per year. Another 

4,500 truck loads per day would need to be needed to deliver 3.8 million tons (3.4 million 
 

33

Mg) of fine sediments, assuming 166 working days per year. The delivery of sand and 

fine sediment would require up to 5,300 total loads per day, which is equivalent to a truck 

dumping a sediment load every 16 seconds. If larger trucks were used with a 10 ton per 

load capacity, the number of truck loads would be reduced in half, but the number of 

truck loads would still be excessive. The endless parade of trucks driving from Antelope 

Point would require that new roads be constructed to bypass the City of Page, Arizona. 

Truck transport would be a 24-mi (38-km) round trip from Antelope Point to below Glen 

Canyon Dam and a 110-mi (180 km) round trip from Antelope Point to Lees Ferry. 

Sediment transport by truck from Antelope Point to Lees Ferry was also considered. 

Larger trucks with a 30-ton hauling capacity could be used, but the trucks would have to 

travel a 110-mile (180-km) round-trip distance along steep and winding grades, which 

would increase the travel times and fuel consumption of the trucks. The annual delivery 

of 1 million tons (0.9 million Mg) of sand would require approximately 130 truck loads 

per day, assuming 250 working days per year. Another 750 truck loads per day would 

need to be needed to deliver 3.8 million tons (3.4 million Mg) of fine sediments, 

assuming 166 working days per year. The delivery of sand and fine sediment would 

require up to 890 total loads per day, which is equivalent to a truck dumping a sediment 

load every 97 seconds. 

2.4.2.3 Slurry Pipeline Overland from Navajo Canyon 

This alternative was determined to be very difficult to implement, more costly than the 

submerged pipelines, and have more environmental impact than the submerged pipelines. 

• Overland access to Navajo Canyon would be very difficult because of the steep 

bedrock topography of the canyon, there is more than 1,000 feet of elevation 

difference between the reservoir and the plateau, and no roads cross this pristine 

area. 

• Pumping plants would be required for every 50 feet of elevation gain and a road 

would have to be constructed to each pumping plant. Road construction would 

require blasting and excavation in this pristine area. At least 20 pumping plants 

would be required just to deliver sediment to the top of the plateau. 

• The high elevation difference along this overland route would also require a 

leaner sediment concentration than a pipeline along Lake Powell. 

• A floating pipeline or system of barges would still be required to deliver sediment 

from the dredging operation to where the overland pipeline would reach the 

reservoir shoreline in Navajo Canyon. 
 

34

2.5 Sand Storage Alternatives 

For the alternative pipeline alignment to Lees Ferry, sand would be settled from the 

slurry and stockpiled on the canyon plateau near Lees Ferry, overlooking the Colorado 

River from the left side, looking downstream (see figure 11). The stockpiled sand would 

be dumped into the Colorado River up to one month before the release of the beachbuilding flow. Two settling basins would alternatively be used to settle the sand from the 

slurry pipeline. Each basin would be operated for about one month while the other basin 

is drained and cleaned out. Water from the settling basin would drain through the 

inclined shaft into the Colorado River. The settling basin operation would run year round 

to meet the quantities of sand needed. Each basin would be 900 feet by 250 feet (275 m 

by 75 m) and each basin would be expected to fill in about one month. 

Bulldozers, loaders, and trucks would be used to remove the sand from each settling 

basin for storage of 1 million tons of sand on the plateau overlooking the Colorado River. 

The sand storage volume would be 2,500 feet (760 m) long, 400 feet (120 m) wide, and 

20 feet (6 m) high. The stored sand would be pushed into the Colorado River by 

bulldozers (D-10) prior to the release of the beach-building flow. 

The sands would be removed from the stilling basin by a truck, bulldozer and loader 

operation. The dozer would assist the loading of the sand into dump trucks or trucks with 

40 foot dump trailers. The trucks would then haul the sands up to one half mile to the 

stockpile area where they would dump and store the sands. It is estimated that one D8 

series dozer and 999 series loader would be needed to fill the haul trucks. Four to five 

haul trucks would be needed to keep up with the loader. These estimates are based on 

10 hour shifts and 20 days per month, see Appendix B. 

Approximately 1 million tons of sand (0.9 million Mg) would be stockpiled on the 

canyon plateau overlooking the Colorado River near Lees Ferry. At the appropriate time, 

the stockpiled sands would be pushed into the Colorado River. This would be 

accomplished about one month prior to the beach-building flow. To accomplish this, up 

to eight D10 series bulldozers may be required. The dozers would push the stock piled 

sand over the bank and into the river, where the water would move the sands on 

downstream into the canyon. The D10 series dozers would only be required during the 

time period when the sands need to be pushed into the Colorado River. 

2.6 Summary of Complete Alternatives 

Based on analysis of the sediment augmentation system components, five alternatives 

were selected for cost estimation. The first three alternatives would meet the objectives 

for turbidity and sand. The last two alternatives would only meet the objectives for 

turbidity and not for sand. 

1. Silt-clay and sand slurry pipelines from Navajo Canyon to below Glen Canyon 

Dam. 
 

35

2. Silt-clay and sand slurry Pipelines from Navajo Canyon to Lees Ferry. 

3. Silt-clay slurry pipelines from Navajo Canyon to Lees Ferry and sand pipelines 

from Navajo Canyon to below Glen Canyon Dam. 

4. Silt-clay slurry pipelines from Navajo Canyon to Lees Ferry (no sand slurry 

pipelines). 

5. Silt-clay slurry pipelines from Navajo Canyon to below Glen Canyon Dam (no 

sand slurry pipelines). 

Theses alternatives contrast the range of sediment delivery locations and the size of 

sediments (clay, silt, and sand). A summary of these five alternatives is presented in 

table 6. 
36

Table 6. Summary of complete sediment augmentation alternatives. 

System components Alternative 1 Alternative 2 Alternative 3 AlternaSediment source area Navajo Canyon Navajo Canyon Navajo Canyon Navajo C Dredges 2 Clamshells 2 Clamshells 2 Clamshells 2 ClamsFine sediment slurry pipeline delivery location 

Below Glen 

Canyon Dam Near Lees Ferry Near Lees Ferry Near Lees 

 Submerged route distance 18 mi (29 km) 18 mi (29 km) 18 mi (29 km) 18 mi (2 Number of floating pumping plants 3 3 3 3  Overland buried slurry pipeline  Buried route distance 11 mi (18 km) 50 mi (80 km) 50 mi (80 km) 50 mi (8

Number of land-based pumping plants 2 12 12 12 

 Number of pressure reducing stations 0 10 10 10 Sand slurry pipeline delivery location Below Glen Canyon Dam Near Lees Ferry Below Glen Canyon Dam  Submerged  Submerged route distance 18 mi (29 km) 18 mi (29 km) 18 mi (29 km) 0  Number of floating pumping plants 3 3 3 0  Overland buried slurry pipeline  Buried route distance 11 mi (18 km) 50 mi (80 km) 11 mi (18 km) 0 

Number of land-based pumping plants 3 14 3 0 

 Number of pressure reducing stations 0 10 0 0 Sand storage area Colorado River in Glen Canyon Terrestrial site near Lees Ferry Colorado River in Glen Canyon non
 

37

3.0 Appraisal-level Cost Estimates 

An appraisal cost estimate represents a preliminary project cost in determining whether 

more detailed investigations of a potential project are justified. These estimates are 

intended to be used as an aid in selecting the most economical plans by comparing 

alternative features. Given the preliminary investigations at this phase, appraisal cost 

estimates are not suitable for requesting project authorization or construction funding 

appropriations from the Congress. 

 

Appraisal cost estimates (January 2006 dollars) were prepared for five sediment 

augmentation alternatives. A summary comparison of these cost estimates are presented 

in table 7. More cost estimate details for each alternative are presented in tables 8 

through 12. 

These appraisal-level costs estimates do not directly include any costs for the purchase of 

land or right-of-way for pipelines or pump stations. Also, the estimates do not include 

any costs associated with traffic control or traffic disruption during construction 

activities. These cost estimates do include operating costs for the dredge system and 

power for the pump stations. Maintenance and replacement costs for pumps and motors 

are included, but not for any other items. These appraisal-level cost estimates are 

sufficient for comparing alternatives, but a more complete investigation of operations, 

maintenance, and replacement costs are needed at the next (feasibility) level of analysis. 

Table 7. Summary comparison of appraisal cost estimates for five 

sediment augmentation alternatives. 

Alternative 

Project 

Capital Cost 

(Jan. 2006) 

Annual 

Operating Cost 

(Jan. 2006) 

1. Sand and Silt-Clay Slurry Pipelines from Navajo 

Canyon to below Glen Canyon Dam $220 million $6.6 million/yr 

2. Sand and Silt-Clay Slurry Pipelines from Navajo 

Canyon to Lees Ferry $430 million $17 million/yr 

3. Sand Pipelines from Navajo Canyon to below Glen 

Canyon Dam and Silt-Clay Slurry Pipelines from 

Navajo Canyon to Lees Ferry $380 million $11 million/yr 

4. Silt-Clay Slurry Pipelines from Navajo Canyon to 

Lees Ferry (No sand slurry pipelines) $300 million $7.9 million/yr 

5. Silt-Clay Slurry Pipelines from Navajo Canyon to 

below Glen Canyon Dam (No sand slurry pipelines) $140 million $3.6 million/yr 
 

38

Table 8. Appraisal-level cost estimate for alternative 1 (January 2006 dollars). 

Alternative 1: Sand and Silt-Clay Slurry Pipelines from Navajo Canyon to 

below Glen Canyon Dam 

 

Dredge system construction $9,693,340

 

Silt and clay slurry pipelines (three, 24-in diameter pipes, 7.57 cfs per pipe) $48,065,190

 18 miles floating HDPE pipelines 

 11 miles buried HDPE pipelines 

Silt and Clay pumping plants 

 3 floating plants 

 2 land-based plants 

 

Directional drilling with inlet basin and valve 

discharge structure 1,600 feet 

 

Sand slurry pipeline (three, 12-inch diameter pipes, 2.03 cfs per pipe) $23,943,102

 18 miles floating HDPE pipelines 

 11 miles buried HDPE pipelines 

Sand pumping plants 

 3 floating plants 

 3 land-based plants 

 

Directional drilling with inlet basin and valve 

discharge structure 1,600 feet 

 

Electrical plant control and distribution $1,673,000

Electrical power distribution (buried lines and submerged marine cabling) $20,130,000

SCADA System requirements $4,356,600

 

Subtotal $107,861,232

Mobilization 5% $5,400,000

Subtotal with mobilization $113,261,232

Unlisted items 15% $16,989,185

Contract Cost $130,000,000

Contingencies 25% $35,000,000

Field Cost $165,000,000

Non-contract cost allowance 30% $50,000,000

Project Cost $220,000,000

 

Annual Operations 

Dredge system operations $3,276,424 

 

Power for pump stations $3,225,600 

Maintenance and replacement of pump motors $130,000 

Total Operations Cost $6,600,000 
 

39

Table 9. Appraisal-level cost estimate for alternative 2 (January 2006 dollars). 

Alternative 2: Sand and Silt-Clay Slurry Pipelines from Navajo Canyon to 

Lees Ferry 

 

Dredge system construction $9,693,340

Lees Ferry sand storage area $2,071,000

 

Silt and clay slurry pipelines (three, 24-inch diameter pipes, 7.57 cfs per pipe) $114,672,135

 18 miles floating HDPE pipelines 

 50 miles buried HDPE pipelines 

Silt and clay pumping plants 

 3 floating plants 

 12 land-based plants 

 10 pressure reducing stations 

Directional drilling with inlet basin and valve 

discharge structure 300 Feet 

 

Sand slurry pipeline (three, 12-inch diameter pipes, 2.03 cfs per pipe) $47,366,565

 18 miles floating HDPE pipelines 

 50 miles buried HDPE pipelines 

Sand pumping plants 

 3 floating plants 

 14 land-based plants 

 10 pressure reducing stations 

Directional drilling with inlet basin and valve 

discharge structure 300 Feet 

Electrical plant control and distribution $4,916,000

Electrical power distribution (buried lines and submerged marine cabling) $30,010,000

SCADA System requirements $9,725,600

Subtotal $218,454,640

Mobilization 5% $11,000,000

Subtotal with mobilization $229,454,640

Unlisted items 15% $34,418,196

Contract Cost $260,000,000

Contingencies 25% $70,000,000

Field Cost $330,000,000

Non-contract cost allowance 30% $100,000,000

Project Cost $430,000,000

Annual Operations 

Dredge system operations $3,276,424

Lees Ferry sand storage operations $3,928,800

Power for pump stations $9,487,800

Maintenance and replacement of pump motors $380,000

Total Operations Cost $17,000,000
 

40

Table 10. Appraisal-level cost estimate for alternative 3 (January 2006 dollars). 

Alternative 3: Sand Pipelines from Navajo Canyon to below Glen Canyon 

Dam and Silt-Clay Slurry Pipelines from Navajo Canyon to Lees Ferry 

 

Dredge system construction $9,693,340

 

Silt and clay slurry pipelines (three, 24-inch diameter pipes, 7.57 cfs per pipe) $114,672,135

 18 miles floating HDPE pipelines 

 50 miles buried HDPE pipelines 

Silt and clay pumping plants 

 3 floating plants 

 12 land-based plants 

 10 pressure reducing stations 

Directional drilling with inlet basin and valve 

discharge structure 300 feet 

 

Sand slurry pipeline (three, 12-inch diameter pipes, 2.03 cfs per pipe) $23,943,102

 18 miles floating HDPE pipelines 

 11 miles buried HDPE pipelines 

Sand pumping plants 

 3 floating plants 

 3 land-based plants 

 

Directional drilling with inlet basin and valve 

discharge structure 1,600 feet 

 

Electrical plant control and distribution $3,783,000

Electrical power distribution (buried lines and submerged marine cabling) $32,610,000

SCADA System requirements $6,900,600

 

Subtotal $191,602,177

Mobilization 5% $9,600,000

Subtotal with mobilization $201,202,177

Unlisted items 15% $30,180,327

Contract Cost $230,000,000

Contingencies 25% $60,000,000

Field Cost $290,000,000

Non-contract cost allowance 30% $87,000,000

Project Cost $380,000,000

 

Annual Operations 

Dredge system operations $3,276,424

 

Power for pump stations $7,408,800

Maintenance and replacement of pump motors 

Total Operations Cost $11,000,000
 

41

Table 11. Appraisal-level cost estimate for alternative 4 (January 2006 dollars). 

Alternative 4: Silt-Clay Slurry Pipelines from Navajo Canyon to Lees Ferry 

(No sand slurry pipelines) 

 

Dredge system construction $4,846,670

 

Silt and clay slurry pipelines (three, 24-inch diameter pipes, 7.57 cfs per pipe) $114,672,135

 18 miles floating HDPE pipelines 

 50 miles buried HDPE pipelines 

Silt and clay pumping plants 

 3 floating plants 

 12 land-based plants 

 10 pressure reducing stations 

Directional drilling with inlet basin and valve 

discharge structure 300 feet 

No sand slurry pipelines 

 

 

Electrical plant control and distribution $3,165,000

Electrical power distribution (buried lines and submerged marine cabling) $21,910,000

SCADA System requirements $4,847,800

 

Subtotal $149,441,605

Mobilization 5% $7,500,000

Subtotal with mobilization $156,941,605

Unlisted items 15% $23,541,241

Contract Cost $180,000,000

Contingencies 25% $50,000,000

Field Cost $230,000,000

Non-contract cost allowance 30% $69,000,000

Project Cost $300,000,000

 

Annual Operations 

Dredge system operations $1,380,786

 

Power for pump stations $6,274,800

Maintenance and replacement of pump motors $260,000

Total Operations Cost $7,900,000
 

42

Table 12. Appraisal-level cost estimate for alternative 5. 

Alternative 5: Silt-Clay Slurry Pipelines from Navajo Canyon to below 

Glen Canyon Dam (No sand slurry pipelines) 

 

Dredge system construction $4,846,670

 

Silt and clay slurry pipelines (three, 24-inch diameter pipes, 7.57 cfs per pipe) $48,065,190

 18 miles floating HDPE pipelines 

 11 miles buried HDPE pipelines 

Silt and clay pumping plants 

 3 floating plants 

 2 land-based plants 

 

Directional drilling with inlet basin and valve 

discharge structure 1,600 feet 

 

No sand slurry pipelines 

Electrical plant control and distribution $1,055,000

Electrical power distribution (buried lines and submerged marine cabling) $12,030,000

SCADA System requirements $2,170,800

 

Subtotal $68,167,660

Mobilization 5% $3,400,000

Subtotal with mobilization $71,567,660

Unlisted items 15% $10,735,149

Contract Cost $82,000,000

Contingencies 25% $23,000,000

Field Cost $105,000,000

Non-contract cost allowance 30% $32,000,000

Project Cost $140,000,000

 

Annual Operations 

Dredge system operations $1,380,786

 

Power for pump stations $2,091,600

Maintenance and replacement of pump motors $90,000

Total Operations Cost $3,600,000
 

43

4.0 Environmental Impacts 

A brief listing of environmental impacts from the sediment augmentation alternatives is 

presented below: 

• Construction activities of the slurry pipelines and pumping plants would create 

noise and visual impacts. 

• The discharge of sediment into the Colorado River would impact water quality 

and would require compliance with the Clean Water Act (see section 4.1.1). 

• Tunneling through the bed rock at the Antelope Point shoreline and the canyon 

wall below Glen Canyon Dam would create a permanent disturbance to the 

landscape. 

• Excavation for the buried pipelines and tunneling could affect cultural resources. 

• The dredging operations would limit access in portions of Navajo Canyon 

upstream of the most downstream dredge. 

• Operations of the clamshell dredges and floating pumping plants would create 

noise impacts on Lake Powell. 

• Presence of the floating pumping plants and overland pumping plants would 

create visual impacts. 

• Sand settling basins and stockpile areas would create dust, noise, and visual 

impacts for alternative 2 near Lees Ferry. 

4.1 Water Quality 

Water quality would be impacted by the discharge of sediments to the Colorado River, 

either below Glen Canyon Dam or near Lees Ferry. The primary impact to water quality 

would be the increase in suspended sediment concentration and turbidity. The 

alternatives all use the same sediment source from Navajo Canyon. 

A composite sediment sample collected during November 2004 from Navajo Canyon was 

submitted to the USGS Mineral Resources Laboratory in Denver, Colorado, for chemical 

analysis (see Appendix A for details). The sample was analyzed for 39 elements, some 

of which would be considered contaminants, but most of which would not be. The 

elemental composition of the sample agrees well with that of typical sandstone. 

Potential contaminants of particular concern include mercury and selenium. Mercury is a 

concern because of the proximity of the canyon to the Navajo Powerplant. However, 
 

44

mercury was below its detection limit. Elevated selenium concentrations have been 

implicated in wildlife toxicity in irrigation return flows in the Upper Colorado Basin. 

Selenium was also below its detection limit in the sample. A comparison of other 

potential contaminants with their respective sediment quality guidelines showed none to 

be elevated. Although this initial screening showed no evidence of the presence of 

contaminants in the sediments, a much broader sampling program would be needed to 

confirm the preliminary conclusion. 

4.1.1 Regulations 

The discharge of suspended sediment from Lake Powell to the Colorado River would 

have to be evaluated against the Corps of Engineers (Corps) and the Environmental 

Protection Agency (EPA) regulations implementing Section 404 of the Clean Water Act. 

Section 404 regulates the discharge of dredged or fill material to waters of the United 

States. The regulations require a permit from the Corps before such a discharge can be 

made. All permits are reviewed by the EPA for compliance with their regulations 

implementing Section 404(b)(1) of the Clean Water Act. EPA also has veto power over 

any permit under Section 404(c) of the Act. In addition, no permit can be issued without 

first complying with the National Environmental Policy Act. 

Section 401 of the Clean Water Act gives State water quality agencies review authority 

over Federal permits, such as a 404 permit. The State review is limited to compliance 

with State water quality standards. Before a permit can be issued, the State must certify 

that the discharge is in compliance with the water quality standards. In Arizona, the only 

water quality standard that appears to apply is the one for suspended sediment. That 

standard is 80 mg/L for the protection of aquatic life. 

It should be noted that the Arizona water quality standards make a provision for an 

exception from certain water quality standards if a net ecological benefit from the discharge can be demonstrated. Reclamation and the Fish and Wildlife Service made this 

point in the development of the Platte River Endangered Species Recovery Implementation Program in Nebraska. Both the Corps and EPA felt that was a valid point. 

4.2 Cultural Resources 

The submerged sediment slurry pipelines in Lake Powell would not have permanent 

impacts. The dredges, submerged pipelines, buoys, cables, floating pumping plants, and 

electrical power lines could all be removed. The buoy anchors would rest on existing 

reservoir sediment rather than the natural topography of the reservoir bottom. The 

dredges would excavate both existing and future reservoir sediment. 

A tunnel would be drilled in the bedrock near the lake shoreline at Antelope Point and the 

buried pipelines and above-ground pumping plants would cross Navajo Nation lands. 

For the alternative route to below Glen Canyon Dam, directional drilling would be 

required through the canyon bedrock. For the alternative route to Lees Ferry, the buried 
 

45

sediment slurry pipelines, above-ground pumping plants, and pressure reduction stations 

would cross Navajo Nation lands along Highway 89. The settling basins and sand 

storage area near Less Ferry would also be on Navajo Nation lands. 

Attempts have been made to minimize the impacts to cultural resources, but the exact 

impacts are unknown. Cultural resource studies and consultation with the Navajo Nation 

would have to be conducted to estimate the impacts to cultural resources. 
 

46

5.0 Conclusions 

Sediment slurry pipelines that would deliver sediment from the Navajo Canyon arm of 

Lake Powell to the Colorado River below Glen Canyon Dam or near Lees Ferry are 

believed to be technically feasible. Five sediment augmentation alternatives have been 

formulated and evaluated. Alternatives are available to deliver fine sediment and sand to 

the Colorado River, either below Glen Canyon Dam or near Lees Ferry. 

Attempts have been made to formulate each alternative to minimize environmental 

impacts and to avoid cultural resource impacts. No major environmental impacts for any 

of the five alternatives have been identified at this time. 

Sediment source areas in Lake Powell seem to be the most logical choice because of cost 

and because the sediments in Lake Powell would have naturally reached the Colorado 

River below the site of Glen Canyon Dam. Sediment source areas in Navajo Canyon are 

much closer to Glen Canyon Dam than other major source areas in Lake Powell. 

Laboratory analysis of one sediment sample from Navajo Canyon did not detect any 

contaminants above background levels. A more intensive sediment sampling program 

would be needed to verify if this finding is applicable to more of the sediments within 

Navajo Canyon. 

Although the present and future sedimentation volumes in Navajo Canyon may not be 

enough to sustain a Grand Canyon sediment augmentation program over the long term, 

the volumes should be sufficient for one or two decades (see figure 8). Sediments in 

Navajo Canyon could be dredged first and then the submerged slurry pipelines and 

floating pumping stations could be moved to an upstream source such as the Escalante 

River or San Juan River deltas. 

Sediment slurry pipelines can deliver large quantities of sediment, and over long 

distances, much more efficiently and at less cost than barges or trucks. Submerging 

sediment slurry pipelines in Lake Powell appears to be a viable option with much less 

impact than overland routes from major sediment source areas in Lake Powell where no 

direct roads presently exist. 

The augmentation of fine sediment should be considered in conjunction with alternatives 

that would increase the summer water temperatures released from Glen Canyon Dam 

(e.g., selective withdrawal of water from Lake Powell). Native and endangered fish in 

Grand Canyon National Park are impacted by less turbidity and colder water 

temperatures in summer compared to natural conditions (U.S. Department of the Interior, 

Bureau of Reclamation, 1995). Turbidity may provide native fish with cover from 

predation. In the absence of turbid conditions, native fish tend not to be active during the 

day (U.S. Department of the Interior, Bureau of Reclamation, 1995). Although, colder 

water temperatures may impact young-of-the-year native fish in summer, the colder 

temperatures may also keep non-native warm-water fish from migrating upstream 

through Grand Canyon National Park. If water temperatures are increased, there is a 
 

47

concern that non-native warm-water fish may have the advantage (U.S. Department of 

the Interior, Bureau of Reclamation, 1995). The augmentation of fine sediment may 

provide the necessary cover for native and endangered fish. 
 

48

6.0 Future Investigations 

If there is continued interest in pursuing a Grand Canyon sediment augmentation system, 

then the following steps are recommended: 

1. Conduct more sampling and testing of sediments in Lake Powell, especially in 

Navajo Canyon. Additional samples are needed over a larger spatial area, and at 

greater depth, to more thoroughly document grain size distribution and test for the 

presence of contaminants above background levels. 

2. Conduct environmental studies to verify the need for both sand and fine sediment 

augmentation. 

3. Prepare an environmental impact statement with public involvement. 

4. Conduct an engineering feasibility study to refine alternatives, verify technical 

feasibility, and accurately determine costs. 

5. Submit a record of decision and feasibility design report to Congress 

6. Seek congressional authorization. 

7. Conduct a final engineering design with construction specifications. 

8. Obtain construction bids. 

9. Construct and operate the project. 
 

49

7.0 References 

Andrews, E.D., 1991. Sediment transport in the Colorado River Basin, in Colorado River 

Ecology and Dam Management, proceedings of a Symposium, May 24-25, 1990, Santa 

Fe, NM, National Academy Press, Washington, DC, p. 54-74. 

Briggs, Paul H., and Allen L. Meier. 1999. The Determination of Forty Two Elements in 

Geological Materials by Inductively Coupled Plasma – Mass Spectrometry. U.S. 

Geological Survey Open-file Report 99-166, USGS, Denver, Colorado. 15 pp. 

Church, S.E., B.A. Kimball, D.L. Fey, D.A. Ferderer, D.J. Yager, and R.B. Vaughn. 

1997. Source, Transport, and Partitioning of Metals between Water, Colloids, and Bed 

Sediments of the Animas River, Colorado. U.S. Geological Survey Open-file Report 

97-151, USGS, Denver, Colorado. 135 pp. 

Crockett, Alan B., and Robert R. Kinnison. 1977. Mercury Distribution in Soil Around a 

Large Coal-fired Power Plant. EPA-600/3-77-063, U.S Environmental Protection 

Agency, Environmental Monitoring and Support Laboratory, Las Vegas, Nevada. 14 pp. 

Emsley, John. 1998. The Elements. 3rd Ed., Oxford University Press, Inc. New York, 

New York. 292 pp. 

Ferrari, R.L, 1988. “1986 Lake Powell Survey,” Bureau of Reclamation, Denver, 

Colorado. 

Fortescue, John A.C. 1992. Landscape geochemistry: retrospect and prospect—1990. 

Applied Geochemistry 7: 1-53. 

Gornitz, Vivien, and J.M. Warde, 1972. Niobium (Columbium): Element and 

Geochemistry. In: Encyclopedia of Geochemistry and Environmental Sciences. 

Rhodes W. Fairbridge (Ed.). Dowden, Hutchinson & Ross, Stroudsburg, Pennsylvania. 

Pp. 793-795. 

Gustavsson, N., B. Bølviken, D.B. Smith, and R.C. Severson. 2001. Geochemical 

Landscapes of the Conterminous United States — New Map Presentations for 22 

Elements. U.S. Geological Survey Professional Paper 1648. USGS, Denver, Colorado. 

38 pp. 

Hart, R.J., H.E. Taylor, R.C. Antweiler, G.G. Fisk, G.M. Anderson, D.A. Roth, M.E. 

Flynn, D.B. Peart, Margot Truini, and L.B. Barber. 2004. Physical and Chemical 

Characteristics of Knowles, Forgotten, and Moqui Canyons, and Effects of Recreation 

Use on Water Quality, Lake Powell, Arizona and Utah. U.S. Geological Survey 

Scientific Investigations Report 2004-5120. USGS, Denver, Colorado. 43 pp. 
 

50

Hageman, Phillip L., and Eric Welsch, 1996. Arsenic, antimony, and selenium by flow 

injection or continuous flow-hydride generation-atomic absorption spectrophotometry. 

In: Analytical methods manual for the Mineral Resource Surveys Program, Belinda F. 

Arbogast (ed.), U.S. Geological Survey Open-file Report 96-525, USGS, Denver, 

Colorado. Pp. 24-30. 

Ingersoll, Christopher G., Donald D. Macdonald, Ning Wang, Judy L. Crane, L. Jay field, 

Pam S. Haverland, Nile E. Kemble, Rebekka A. Lindskoog, Corinne Severn, and Dawn 

E. Smorong. 2000. Prediction of sediment toxicity using consensus-based freshwater 

sediment quality guidelines. United States Geological Survey Report to the U.S. 

Environmental Protection Agency. EPA 905/R-00-007, EPA, Great Lakes National 

Program Office, Chicago, Illinois. 25 p. + 2 Figs., 5 Tables, App. 

Macdonald, D.D., C.G. Ingersoll, and T.A. Berger. 2000. Development and Evaluation 

of Consensus-Based Sediment Quality guidelines for Freshwater Ecosystems, Arch. 

Environ. Contam. Toxicol. 39:20-31. 

Morris, G.L. and Fan, J. 1997. Reservoir Sedimentation Handbook: design and 

management of dam, reservoirs, and watersheds for sustainable use, McGraw Hill, 

New York, New York, ISBN 0-07-043302-X. 

O’Leary, Richard M., Phillip L. Hageman, and James G. Crock. 1996. Mercury in 

water, geologic, and plant materials by continuous flow-cold vapor-atomic absorption 

spectrometry. In: Analytical methods manual for the Mineral Resource Surveys 

Program, Belinda F. Arbogast (ed.), U.S. Geological Survey Open-file Report 96-525, 

USGS, Denver, Colorado. Pp. 42-50. 

Parker, Raymond L. 1967. Data of Geochemistry, Sixth Edition, Chapter D. 

Composition of the Earth’s Crust. Geological Survey Professional Paper 440-D, United 

States Government Printing Office, Washington, D.C. 19 pp. 

Rubin, D.M., Topping, D.J., Schmidt, J.C., Hazel, J. Kaplinski, M. and Melis, T.S., 2002, 

Recent Sediment Studies Refute Glen Canyon Dam Hypothesis, Eos, American 

Geophysical Union, v. 83, no. 25, p. 273, 277-278. 

Slikkerveer, Anja, and Frederik A. de Wolff. 1996. Toxicity of Bismuth and Its 

Compounds. In: Toxicology of Metals. Louis W. Chang (Ed.). Lewis Publishers, 

Boca Raton, Florida. Pp. 439-454. 

Strand, R.I. and Pemberton, E.L., 1983. “Reservoir Sedimentation Technical Guideline,” 

U.S. Bureau of Reclamation, Denver, Colorado. 

Topping, D.J., Rubin, D.M., and Vierra, L.E. Jr., 2000a. “Colorado River sediment 

transport 1. Natural sediment supply limitation and the influence of Glen Canyon Dam,” 

Water Resources Research, VOL. 36, NO. 2, pages 515–542, February 2000. 
 

51

Topping, D.J., Rubin, D.M., Nelson, J.M., Kinzel, P.J. III, 2000b. “Colorado River 

sediment transport 2. Systematic bed-elevation and grain-size effects of sand supply 

limitation,” Water Resources Research, VOL. 36, NO. 2, pages 543–570, February 2000. 

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Washington, D.C. Numbered by Chapter. 

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of Glen Canyon Dam operations on downstream sand transport and sandbars along the 

Colorado River in Grand Canyon, in Gloss, S.P., Lovich, J.E., and Melis, T.S., eds., in 

press, The state of the Colorado River ecosystem in Grand Canyon: U.S. Geological 

Survey Circular 1282. 
 

52

Appendix A − Sediment Quality 

James W. Yahnke, Hydrologist 

Water Resources Planning and Operations Support Group 

During a field trip to Lake Powell during November 2004, a sample of Navajo Canyon 

sediment was collected for a variety of analyses. In addition to various physical 

characteristics, the chemical composition was analyzed. For the chemical analysis, the 

sample was dried and sieved through a 0.25 mm mesh. The sample was submitted to the 

U.S. Geological Survey (USGS) Mineral Resources Laboratory in Denver, Colorado. 

The sample was digested in the laboratory and analyzed for 37 elements by ICP-MS as 

described in Briggs and Meier (1999). Mercury was analyzed by cold-vapor atomic 

absorption (O’Leary et al., 1996), and selenium was analyzed by hydride generation 

atomic absorption (Hageman and Welsch, 1996). The results are presented in Table 13. 

In addition to the analytical results of the analysis of the Navajo Canyon sediment 

samples, Table 13 shows two different estimates of the elemental composition of the 

earth’s crust. Crustal abundance values (CAV) as presented in Table 13 can serve as a 

basis for comparison to evaluate potential contaminants. The CAV represents the 

average elemental composition of the various rock types that make up the earth’s crust. 

The elements are weighted by the average amount of each rock type in the crust. If a 

sample result deviates greatly from the average composition, then there should be a 

reason for that deviation. For example, in mineral exploration, areas characterized by 

metal concentrations 3 or more times above the CAV are routinely investigated (Church 

et al., 1997). In the case of Navajo Canyon, it may be that the sediments came from an 

area that deviates greatly from the average, or in the case of very high values, the 

deviation may indicate contamination. 

The results in Table 13 do not indicate contamination. If anything, most element 

concentrations are inordinately low in comparison with the CAV data. The only sample 

result that meets the criterion for mineral exploration is the bismuth concentration. 

However, that is only true of the Fortescue (1992) CAV; the Emsley (1998) CAV is over 

5 times higher than the Fortescue (1992) CAV and the Navajo Canyon result is only 

about twice as high as the Emsley (1998) CAV (Table 13). As far as bismuth is 

concerned, it is regarded as one of the less toxic heavy metals and is commonly used as a 

medicine for stomach upsets (Emsley, 1998; Slikkerveer and de Wolff, 1996). 

Section 404 of the Clean Water Act (CWA) regulates the discharge of dredged materials 

to waters of the United States. The sediment enhancement project would be subject to 

regulation under Section 404 of the CWA. A major concern under the regulations is 

potential toxicity of the discharge sediments. The EPA and Corps of Engineers (EPA, 

1998) have developed a tiered approach to sediment quality evaluation. Over the course 

of the last decade, there has been an effort to develop sediment quality guidelines (SQG) 

for screening sediments for toxicity. The most recent, which were developed for use in 

the Great Lakes, are shown in Table 14. 
 

53

Table 13. Comparison of the results from an ICP-MS scan of the Navajo Canyon 

sediment sample with crustal abundance values from 2 sources (all in ppm) 

Crustal Abundance Element Navajo Canyon Fortescue (1992) Emsley (1998) 

Silver Ag < 3 0.08 0.07 

Aluminum Al 39,800 83,600 82,000 

Arsenic As 3.7 1.8 1.5 

Barium Ba 493 390 500 

Beryllium Be 1 2 2.6 

Bismuth Bi 0.1 0.0082 0.048 

Calcium Ca 26,400 46,600 41,000 

Cadmium Cd 0.07 0.16 0.11 

Cerium Ce 28.6 66.4 68 

Cobalt Co 4 29 20 

Chromium Cr 20.1 122 100 

Cesium Cs 3.2 2.6 3 

Copper Cu 10.4 68 50 

Iron Fe 11,000 62,200 41,000 

Gallium Ga 7.5 19 18 

Mercury Hg < 0.02 0.086 0.05 

Potassium K 23,900 18,400 21,000 

Lanthanum La 14.8 34.6 32 

Lithium Li 32 18 20 

Magnesium Mg 9,640 27,640 23,000 

Manganese Mn 344 1,060 950 

Molybdenum Mo 0.24 1.2 1.5 

Sodium Na 3,200 22,700 23,000 

Niobium Nb 5.1 20 20 

Nickel Ni 7.5 99 80 

Phosphorus P 360 1,120 1,000 

Lead Pb 11.8 13 14 

Rubidium Rb 74.8 78 90 

Antimony Sb 0.32 0.2 0.2 

Scandium Sc 4.3 25 16 

Selenium Se < 0.1 0.05 0.05 

Strontium Sr 102 384 370 

Thorium Th 4.5 8.1 12 

Titanium Ti 1,300 6,320 5,600 

Thallium Tl 0.5 0.72 0.6 

Uranium U 1.3 2.3 2.4 

Vanadium V 25 136 160 

Yttrium Y 10.7 31 30 

Zinc Zn 27.8 76 75 
 

54

Table 14. Comparison of sediment collected at upper reach of Navajo Canyon with 

EPA sediment quality guidelines (Ingersoll et al., 2000; MacDonald et al., 2000) 

Guidelines (ppm) Comparison Element Observed (ppm) TEC PEC TEC PEC 

Arsenic 3.7 9.79 33 < TEC < PEC 

Cadmium 0.07 0.99 4.98 < TEC < PEC 

Chromium 20.1 43.4 111 < TEC < PEC 

Copper 10.4 31.6 149 < TEC < PEC 

Lead 11.8 35.8 128 < TEC < PEC 

Mercury < 0.02 0.18 1.06 < TEC < PEC 

Nickel 7.5 22.7 48.6 < TEC < PEC 

Silver < 3 1 3.7 — < PEC 

TEC – Threshold Effects Concentration 

PEC – Probable Effects Concentration 

Table 14 shows two different sets of SQGs. The first, which is labeled as TEC, 

represents a concentration at which effects are not expected to occur, while the PEC is a 

concentration above which adverse effects are expected to frequently occur (Ingersoll et 

al., 2000). As can be seen in Table 14, all of the samples from Navajo Canyon are below 

the TEC concentrations and the sediment should present no hazard to aquatic life. 

However, only one sample has been collected. Before the sediment can be deemed 

completely safe, more samples would have to be collected and analyzed. Nevertheless, 

the one sample does indicate that there are likely no contributing sources of the toxic 

substances shown in Table 14. 

The sample was analyzed for mercury because of the proximity of the site to Navajo 

Powerplant. The results do not indicate any significant local deposition of airborne 

mercury (Table 14). A study of the Four Corners Powerplant, which is also located on 

the Navajo Nation, showed that residue levels of mercury in soils near the powerplant 

were low (Crockett and Kinnison, 1977). The results from Navajo Canyon are consistent 

with that finding. 

Parker (1967), in addition to a set of CAV data, presents the average composition of 

various types of sedimentary rocks. Figure 19 shows a plot of the Navajo Canyon results 

plotted against the composition of a typical sandstone as presented in Parker (1967). For 

the most part, the fit of the data to the sandstone chemical profile is rather good. There 

are a few elements that plot away from the line, but the major elements plot reasonably 

close to it. Among the major ions, potassium plots farthest from the typical sandstone 

line. Gustavsson et al. (2001) show that potassium is somewhat elevated (2.1-2.3 ppm) 

in surficial rocks of the Colorado Plateau and even higher in the Rocky Mountains that 

constitute the headwaters of the Colorado River. In general, the data, including 

potassium, fit reasonably well to the line of the typical sandstone. 

A number of trace elements plot well above the typical sandstone line. The most obvious 

are barium (Ba), copper (Cu), nickel (Ni), and niobium (Nb). Based on the information 
 

55

in Gustavsson et al. (2001), the Colorado Plateau surficial deposits are much higher than 

the typical sandstone in barium (475-500), copper (10-40), and nickel (10-20). The data 

from Navajo Canyon are actually low by Colorado Plateau standards (compare data in 

table 13 with the preceding). 

Cd

Mo Sb

Tl

BeU

CoCs ScAs Nb Th

Ni Ga Cu Pb LaCr ZnVLi

Rb Sr

Mn P

Ti

Na

MgFe

Al

Y

Ba

Ce

K Ca

0.01 0.1 1 10 100 1000 10000 100000

Typical Sandstone (ppm)

0.01

0.1

1

10

100

1000

10000

100000

Canyon Sediment (ppm)

Sed. Conc. Sandstone

Cd

Mo Sb

Tl

BeU

CoCs ScAs Nb Th

Ni Ga Cu Pb LaCr ZnVLi

Rb Sr

Mn P

Ti

Na

MgFe

Al

Y

Ba

Ce

K Ca

0.01 0.1 1 10 100 1000 10000 100000

Typical Sandstone (ppm)

0.01

0.1

1

10

100

1000

10000

100000

Canyon Sediment (ppm)

Sed. Conc. Sandstone

Figure 19. Comparison of the concentrations of elements from the ICP-MS scan of 

Navajo Canyon sediments with concentrations typical of sandstone. 

The niobium concentration is about halfway between what is typical of sandstones and 

shales, based on the data in Parker (1967). However, the niobium concentration in Table 

13 is only about 1⁄4 of its CAV. In the weathering of rocks, niobium tends to become 

concentrated in hydrolysate sediments and is therefore found in shales and clays, rather 

than limestone or sandstone (Gornitz and Warde, 1972). The high niobium concentration 

in Navajo Canyon may simply reflect the presence of fines in the sediment sample. 

Hart et al. (2004) studied several side canyons in Glen Canyon Reservoir in 2002. A 

complete chemical analysis on duplicate bed sediment samples was reported from Moqui 

Canyon, which is located about 1⁄2 mile up the reservoir from Bullfrog Marina. Their data 

are plotted on Figure 20 for comparison with the Navajo Canyon data and to show within 

sample variation. The typical sandstone line is also shown on Figure 20. Unlike the 

Navajo Canyon data, the major ions from Moqui Canyon plot parallel to, but below, the 

typical sandstone composition line. The elements that plotted above the typical sandstone data on Figure 19, i.e. barium (Ba), copper (Cu), and nickel (Ni), also plot above 

the line on Figure 20. Although there are no data for niobium from Moqui Canyon, 

tantalum (Ta), which is chemically similar to niobium, occupies a somewhat similar 

position on Figure 20. 
 

56

Figure 20. Comparison of the concentrations of elements in duplicate samples of 

Moqui Canyon sediments with concentrations typical of sandstone (Parker, 1967). 

The differences between the data on figures 19 and 20 appear to represent the equivalent 

of a dilution in water. The total of the elements on Figure 19 is about 110,000 ppm, 

while their total in the typical sandstone is about 100,000. Because the total is similar, 

the Navajo Canyon data plot near the line. The total of the elements on Figure 20 for the 

Moqui Canyon data is about 50,000 ppm, or about 1⁄2 the total of the Navajo Canyon 

sample and the typical sandstone composition. Because the total is lower, the individual 

elements plot somewhat uniformly below the typical sandstone line. 
 

57

If the sample analyses were anywhere near complete, the total of the elements would 

approach 1 (actually 1 million ppm). Major components of the typical sandstone include 

silicon (36.8 percent) and oxygen (46 percent). Neither of these are included in the 

analytical totals from Glen Canyon Reservoir. A petrographic analysis of a split of the 

Navajo Canyon sediment sample was about 90 percent quartz. Based on the weight of 

silicon in quartz, the Navajo Canyon sample would have been about 47 percent quartz. 

Although the elements are plotted on figures 19 and 20, they, like the silicon, would most 

likely be present in the sediments as oxides of the elements. The evident dilution that is 

mentioned above may simply be a result of differing amounts of quartz sand in the 

sediments. 

In addition to the duplicate sample shown above, Hart et al. (2004) collected a total of 12 

other samples. However, they only reported trace element concentrations in those 

samples, although aluminum and iron were also included. From the perspective of this 

study, Hart et al. (2004) reported selenium concentrations in the sediments of all 3 of the 

canyons. Selenium is a known contaminant in the Green, San Juan, and Colorado rivers 

above Glen Canyon Reservoir. However, there was no detectable selenium in any of 

those 12 samples. The Navajo Canyon sample also had no detectable selenium 

(Table 13), indicating that the probability of selenium contamination, as it is in Moqui 

Canyon, is low. 

The preceding represents a preliminary analysis of potential contamination based on only 

1 sediment sample. While 1 sample may be enough to discourage further investigation if 

a high degree of contamination is indicated, a single sample cannot define an absence of 

contamination. If sediment delivery from Lake Powell proves to be physically and 

economically viable, then further investigation of sediment contamination would be 

necessary. It should also be noted that the chemical results reported here are based on a 

different methodology than is recommended for toxicity testing. The digestion used in 

this study included a series of acids to completely (or nearly so) dissolve the sediments. 

For toxicity, a simple aqua regia digestion is recommended (EPA, 1998). In addition, a 

representative set of samples from a much more extensive area of the sediment deposits 

would need to be collected and analyzed to provide better coverage of the source area. 

Nevertheless, given the nature of the local Navajo Canyon drainage basin, there seems to 

be little likelihood that contaminants would be found.
 

58

Appendix B − Dredging Text Research and Information 

Rick J. Christensen and Ryan D. Stephen 

Mechanical Engineers 

Mechanical Equipment Group 

Dredge Design Types 

1.) Suction Dredges 

• Uses suction to remove sediment (some spray out jets to help loosen 

sediment). Mainly used for loose sediments like sand or gravel 

• Original hydraulic dredge design 

2.) Dragline Dredges 

• Use a drag bucket to gather sediments 

• Usually land based 

3.) Clamshell Dredges 

• Come in many configurations but all have two buckets, hinged 

together that close around the material and then are lifted back to the 

surface by a steel cable system 

• Can handle most types of sediments except large boulders 

4.) Auger Dredges 

• Another hydraulic dredge that uses a cutting mechanism to dislodge 

sediment 

• Cutter looks similar to snow plows but is on a long boom that lowers 

the cutter to the desired depth 

• Cuts a wide even path in sediment 

• Good dredge for shallow water situations and fine to medium 

sediments 

5.) Cutter Dredges 

• Similar to auger dredges but uses a corkscrew shaped cutter to cut into 

sediments 

• Most versatile dredge 

6.) Ladder-Bucket Dredges 

• Use a bucket and conveyor system to move material, similar to 

trenchers 
 

59

• Large machines, only can dig as deep as ladder is long, so larger depth 

means larger machine 

7.) Hopper Dredges 

• Another hydraulic dredge that uses a trailing suction device to gather 

sediments; like a big vacuum 

• The dredge is also its own barge, for quick transport 

8.) Rotary or Bucket Head Cutter Dredges 

• Another hydraulic dredge that uses a spinning drum to dislodge 

sediments 

9.) Excavator or Backhoe Dredges 

• These dredges look like large, backhoe arms that have been placed on 

a barge 

• Digging depth limited by the arm length 

Dredging Manufacturers 

1.) Ellicott 

• Largest dredge manufacture in the world 

• Specialize in cutter and auger dredges 

• Models: 

1. Dragon 1170: 

• 150 to 700 yd3/hr 

• 33’ nominal depth (can be ordered to dig deeper) 

• 54’ x 23’ (L x W) 

• www.dredge.com/specs/dragon1170.htm

2. Dragon 1870: 

• 200 to 1,200 yd3

/hr 

• 50’ nominal depth (can be ordered to dig deeper) 

• 82’ x 27’ (L x W) 

• www.dredge.com/specs/dragon1870.htm

3. Super Dragon 4,170: 

• 400 to 4200 yd3/hr 

• 58’ nominal depth (can be ordered to dig deeper) 

• 114’ x 30’ (L x W) 

• www.dredge.com/specs/superdragon4170.htm

4. MC-2000 Mud Cat: 

• 20’ nominal depth (can be ordered to dig deeper) 
 

60

• 48’ x 14.5’ (L x W) 

• www.dredge.com/specs/superdragon4170.htm

2.) IMS Dredges 

• All models use a unique propulsion system called a “Starwheel Drive,” 

which is a pair of paddle wheels that are extended to the bottom of the 

water to push the dredge along 

• All products are auger dredges 

• Models: 

1. Versi Dredge 5012 

• 1,040 yd3

/hr 

• 22’ nominal depth (extensions for 28’, 35’ and 45’) 

• 42’ x 10’ 7” (L x W) 

• http://www.imsdredge.com/products/versidredge/5012.

htm

2. Versi Dredge 7012 

• 1,190 yd3/hr 

• 25’ nominal depth (extensions for 28’, 35’ and 45’) 

• 42’ x 10’ 7” (L x W) 

• http://www.imsdredge.com/products/versidredge/7012.

htm

3.) Twinkle Co. Dredges 

• Specialize in ladder, cutter and bucket style dredges 

• Website provides little explanation of their dredges’ specifications 

• The ladder, boom designs of these dredges would limit their ability to 

dig to deeper depths 

• http://www.twinkleco.com

4.) Dredging Supply Company, Inc. 

• They have deep digging cutter, suction dredges that can dig to 150’+ 

• Specialize in customizing dredges to customers needs 

• Models: 

1. Marlin Class 

• 35’ to 150’+ nominal depth 

• http://www.dscdredge.com/marlin-dredge.html#

2. Shark Cutter Class 

• 65’ nominal depth 

• http://www.dscdredge.com/shark-dredge.html#
 

61

5.) Crisafulli Dredges 

• All dredges are self propelled 

• Can be moved by tractor-trailer on highways 

• Only sell auger style dredges 

• Models: 

1. Rotomite-6000 

• 150 yd3

/hr 

• 20’ nominal depth (60’ optional) 

• 32.5’ x 8.5’ (L x W) 

• http://www.dredge.net/Rotomite1/rfeatures.html

2. Rotomite-8000 

• 325 yd3

/hr 

• 26’ nominal depth (50’ optional) 

• 40’ x 8.5’ (L x W) 

• http://www.dredge.net/Rotomite1/rfeatures.html

6.) Supreme Manufacturing, Inc. 

• Clamshell Dredges 

• Large capacity and deep digging dredges 

• Models: 

1. 13 Yard Clamshell Bucket Dredge 

• 13 yd. bucket 

• Conveyor Off-loader 

• 300’ Digging Depth 

• http://www.suprememfg.net/Dredge.htm

2. 8 Yard Modular Clamshell Dredge 

• 8 yd. bucket 

• Conveyor Off-loader 

• 300’ Digging Depth 

• http://www.suprememfg.net/Dredge.htm
 

62

Dredging 

Possible Uses: 

• Dredge sands and fine sediments from lake delta to begin the sediment 

augmentation system. 

Pros: 

• Clamshell dredges can dredge to 300 foot depths 

• Move large quantities of sand or fine sediments very quickly 

• Mobile, can be moved to dredging sites at various locations 

Cons: 

• All of the dredges seemed to be limited to a 3,000 foot long pipeline distance with 

small elevation change, unless booster pumps are provided 

• Dredges could create navigational hazards with their floating pipelines 

• Most hydraulic dredges seemed to be designed for shallow water use unless they 

were very large vessels 

• Dredges require labor to operate 

• Dredges require placement of anchor points along the shoreline or canyon walls, 

with pulling/positioning lines 
 

63

•

Dredges (Clamshell Type) 

 

 Amount Unit Comments/Assumptions 

Sediment 1,000,000 tons/year Amount of sand or sediment required 

to be moved 

Days 250 days/year Assumes working 5 days a week & 11 

Holidays off 

Amount per Day 4,000 tons/day Amount required to be dredged per 

work day 

 

Bucket Load 8 yards/bucket 

Bucket Load 12.0 tons/bucket 3,000 lbs/yd3 

Tons/hour @ 50 ft 353 tons/hr 80% Efficiency 

Tons/hour @ 100 ft 288 tons/hr 80% Efficiency 

Tons/hour @ 200 ft 211 tons/hr 80% Efficiency 

Tons/hour @ 300 ft 166 tons/hr 80% Efficiency 

Dredging time per day 11.35 hours Time needed to meet 4000 tons/day @ 

50ft 

Time needed to dredge 110 tons 18.72 min Amount per barge 

Dredging time per day 24.08 hours Time needed to meet 4000 tons/day @ 

300ft 

Time needed to dredge 110 tons 39.73 min Amount per barge 

 

Bucket Load 13 yards/bucket 

Bucket Load 19.5 tons/bucket 

Tons/hour @ 50 ft 632 tons/hr 80% Efficiency 

Tons/hour @ 100 ft 534 tons/hr 80% Efficiency 

Tons/hour @ 200 ft 408 tons/hr 80% Efficiency 

Tons/hour @ 300 ft 330 tons/hr 80% Efficiency 

Dredging time per day 6.33 hours Time needed to meet 4000 tons/day @ 

50ft 

Time needed to dredge 110 tons 10.44 min Amount per barge 

Dredging time per day 12.13 hours Time needed to meet 4000 tons/day @ 

300ft 

Time needed to dredge 110 tons 20.02 min Amount per barge 

 

The same amount of fine sediments and sand are required for a total of 2,000,000 tons. The above 

table shows what is needed for only one or the other. 

This does not take into account the travel time of workers to get to the dredges; this could cut into the 

time worked on an 8 hour shift. 

The dredges may need to operate 24 hours a day to continually feed a pipeline, or they would have to 

stockpile the dredged materials on a large barge or at a site on shore (if available) so the pipeline 

could have a surplus to use up over night. 
 

64

Barges 

Possible Uses: 

• Movement of sands and fine sediments from dredging sites to Antelope Point near 

Glen Canyon Dam. 

Pros: 

• No floating pipes, cables or other obstacles for boaters 

• Can move sediment to areas where off-loading would be easier 

• Easy to switch to a new dredging site 

Cons: 

• Need a processing station to load sediments from hydraulic dredges 

• May be too big for the canyons, didn’t find any smaller than 100’ x 30’ 

• Needs support equipment; unloading crane or conveyor system 

• Slow moving, would need tug boats to help assist them in docking 
 

65

Barge Transport

Sand Fine 

Sediment Unit Comments/Assumptions 

Annual sediment load 1,000,000 3,800,000 tons/year Amt. of sand or sediment 

moved/year 

Days per year 250 166 days/year Working 5 days/week, & 

11 Holidays off 

Amount per Day 4,000 22,892 tons/day Amount required to be 

moved/work day 

 

Barge load capacity 110 110 tons/barge 

Barge loads per Day 36 208 barges 

Shortest load distance 28 28 miles Distance/round trip 

Longest load distance 40 40 miles Distance/round trip 

Average barge speed 5 5 mph Average speed 

Short distance time / load 7.6 7.6 hours Avg. time/trip, plus 2 hrs 

unloading 

Long distance time / load 10 10 hours Avg. time/trip, plus 2 hrs 

unloading 

Number of barges required 

for short distance trips 35 198 barges 8 hrs worked/barge/day 

Number of barges required 

for long distance trips 45 260 barges 8 to 10 hrs worked/barge/day 

 

Barge load capacity 110 110 tons/barge 

Barge loads per Day 36 208 barges 

Shortest load distance 28 28 miles Distance/round trip 

Longest load distance 40 40 miles Distance/round trip 

Average barge speed 10 10 mph Average speed 

Short distance time / load 4.8 4.8 hours Avg. time/trip, plus 2 hrs 

unloading 

Long distance time / load 6 6 hours Avg. time/trip, plus 2 hrs 

unloading 

Number of barges required 

for short distance trips 22 125 barges 8 hours worked/barge/day 

Number of barges required 

for long distance trips 27 156 barges 8 hours worked/barge/day 

 

Barge load capacity 110 110 tons/barge 

Barge loads per Day 36 208 barges 

Shortest load distance 28 28 miles Distance/round trip 

Longest load distance 40 40 miles Distance/round trip 

Average barge speed 15 15 mph Average speed 

Short distance time / load 3.87 3.87 hours Avg. time/trip, plus 2 hrs 

unloading 

Long distance time / load 4.67 4.67 hours Avg. time/trip, plus 2 hrs 

unloading 
 

66

Number of barges required 

for short distance trips 18 101 barges 8 hrs worked/barge/day 

Number of barges required 

for long distance trips 21 121 barges 8 hrs worked/barge/day 

 

This does not take into account the travel time of workers to get to the barges; this could cut into 

the time worked on an 8 hour shift. 

Assumes dredging does not interfere with the barges cycle time 

Number of barges required could be doubled, if they have to be filled over a day or night then 

moved to the unloading site during the following day. Barges would have to end a shift at either 

the dredging loading area or at the unloading area. 

Sediment Slurry Piping System 

Possible Uses: 

• Transport of dredged sands or fine sediments from dredging sites to the Colorado 

River below Glen Canyon Dam or Lees Ferry. 

• Moving dredge materials from the dredging sites to a stock piling yard either near 

the dam or downstream by Lees Ferry. 

• If barges used, the slurry pipeline could transport sediments from the off-loading 

site Antelope Point to the delivery points, either below Glen Canyon Dam or to 

Lees Ferry. 

Pros: 

• Easily integrates into most hydraulic or clam shell type dredging systems 

• Less visible impact on surroundings 

Cons: 

• Need for many booster pumps 

• Long distance to transport, especially to Lees Ferry 
 

67

Trucking 

Possible Uses: 

• Moving sands and fine sediments from one site to another 

Truck Requirement: 

• Assuming ~30 tons of sediment per truck, it would take over 33,333 truck loads to 

move one million tons of material a year; that is ~133 truck loads per day 

(assumes 250 working days per year) 

• Assuming ~25 tons of sand or sediment moved per truck, it would take over 

40,000 truck loads to move one million tons of material a year; that is ~160 truck 

loads per day (assumes 250 working days per year) 

• Assuming ~10 tons of sand or sediment moved per truck, it would take over 

100,000 truck loads to move one million tons of material a year; that is ~400 

truck loads per day (assumes 250 working days per year) 

• Assuming ~5 tons of sand or sediment moved per truck, it would take over 

200,000 truck loads to move one million tons of material a year; that is ~800 

truck loads per day (assumes 250 working days per year) 

• It is around a 140 mile round trip from the delta of Navajo Canyon, a 110 mile 

round trip from Antelope Point to Lees Ferry, or around a 24 mile round trip from 

Antelope Point to just below Glen Canyon Dam (uses tunnel) 

Pros: 

• Proven ability to move materials 

• Uses existing structures; road ways in place 

Cons: 

• Noisy 

• Added traffic and wear to the area’s roadways 

• Massive amount of trucks needed 

Off Highway Trucking 

Possible Uses: 

• Moving sands and fine sediments from one site to another 

• Move sediments from dredging sites to a stock piling area close by (2-15 miles) or 

to an area near the dam (15-40 miles) 

• Assuming ~60 tons of material moved per truck, it would take over 16,666 truck 

loads to move one million tons of sediment a year; that is ~67 truck loads per day 

(assumes 250 working days per year) 

• Assuming ~100 tons of material moved per truck, it would take over 10,000 truck 

loads to move one million tons of sediment a year; that is ~40 truck loads per day 

(assumes 250 working days per year) 
 

68

• Caterpillar offers a variety of trucks ranging from 40 to150+ tons 

Pros: 

• Proven ability to move material 

Cons: 

• Needs a new roadway system built specifically for the trucks 

• Would have to use a separate road system, so less interaction with the public 

• Slow movement rate of vehicles; 30-40 mph at top speed 

• Large number of trucks needed 

• Large amount of capital needed to buy and maintain the trucks 

Truck Transport

 Sand Fine 

Sediment Unit Comments/Assumptions 

Annual sediment load 1,000,000 3,800,000 tons/year Amt. of sand or sediment to be 

moved/year 

Days per year 250 166 days/year Work 5 days/week, & 11 Holidays 

off 

Load per day 4,000 22,892 tons/day Amt required to be moved/work day 

 

Truck load capacity 25 25 tons/truck 

Trucks loads per Day 160 916 trucks 

Lees Ferry distance 110 110 miles Distance/round trip 

Average truck speed 20 20 mph Average speed 

Lees Ferry travel time 6 6 hours Time/trip, plus 15min loading & 

15min unloading 

Trucks need for Lees Ferry 120 241 trucks Assumes 8 hrs worked/truck/day 

Average truck speed 30 30 mph Average speed 

Lees Ferry travel time 4.2 4.2 hours Time/trip, plus 15min loading & 

15min unloading 

Trucks need for Lees Ferry 83 477 trucks Assumes 8 hrs worked/truck/day 

 

Truck load capacity 30 30 tons/truck 

Trucks loads per Day 133 763 trucks 

Lees Ferry distance 110 110 miles Distance/round trip 

Average truck speed 20 20 mph Average speed 

Lees Ferry travel time 6 6 hours Time/trip, plus 15min loading & 

15min unloading 

Trucks need for Lees Ferry 63 358 trucks Assumes 8 hrs worked/truck/day 

Average truck speed 30 30 mph Average speed 

Lees Ferry travel time 4.2 4.2 hours Time/trip, plus 15min loading & 

15min unloading 

Trucks need for Lees Ferry 69 397 trucks Assumes 8 hrs worked/truck/day 

 

Truck load capacity 5 5 tons/truck 
 

69

Trucks loads per Day 800 4,578 trucks 

GCD distance 24 24 miles Distance/round trip 

Average truck speed 20 20 mph Average speed 

GCD travel time 1.7 1.7 hours Time/trip, plus 15min loading & 

15min unloading 

Trucks needed for GCD 170 973 trucks Assumes 8 hrs worked/truck/day 

Average truck speed 30 30 mph Average speed 

GCD travel time 1.3 1.3 hours Time/trip, plus 15min loading & 

15min unloading 

Trucks needed for GCD 130 744 trucks Assumes 8 hrs worked/truck/day 

 

Truck load capacity 10 10 tons/truck 

Trucks loads per Day 400 2,289 trucks 

GCD distance 24 24 miles Distance/round trip 

Average truck speed 20 20 mph Average speed 

GCD travel time 1.7 1.7 hours Time/trip, plus 15min loading & 

15min unloading 

Trucks needed for GCD 85 486 trucks Assumes 8 hrs worked/truck/day 

Average truck speed 30 30 mph Average speed 

GCD travel time 1.3 1.3 hours Time/trip, plus 15min loading & 

15min unloading 

Trucks needed for GCD 65 372 trucks Assumes 8 hrs worked/truck/day 

 

Assumes dredging and barging does not hold up trucking 
 

70

Conveyor Systems 

Possible Uses: 

• Loading or offloading barges or trucks 

Pros: 

• Proven ability to move material fast 

• Easily integrates into most dredging systems 

• Can easily fill trucks, barges or stockpile sediments for later use 

Cons: 

• Noisy 

• Visibly ugly 
 

71

Appendix C - Stilling Basin Operations 

Rick J. Christensen and Ryan D. Stephen 

Mechanical Engineers 

Mechanical Equipment Group 

Assumptions Amount Unit Comment 

Sand 1,000,000 tons/year Amount of sand to be moved, weight 

Volume of Sand 666,667 yd3

/year Sand to be moved, volume (1 ton -1.5 cu. yd) 

Stilling Basins 2 basins One is filled while one is emptied, switch monthly 

Sand Gathered per Month 55,556 yd3

/mon Amount of sand gathered by a basin in a month 

 

Cleaning Out Stilling Basins and Moving the Sand to Stockpile Area 

Sand to Move 55,556 yd3

/mon Sand to be moved to stockpile each month 

Sand per Day 2,778 yd3

/day Assumes 20 work days per month 

Yards per Truck 20.0 yd3

/truck Assumes 30 tons per truck, 1.5 tons/cu.yd. 

Truck loads per day 139 trucks 

Truck loads per hour 14 trucks Assumes 10 hour work day 

Load time per truck 4.2 min Time allowed to load each truck 

Turnaround time per Truck 15.0 min Time from loading to being ready to be reloaded 

Trucks Needed 4 trucks 

 

Moving Sand From Stockpile Area Into or Along the River Bank 

(Prior to and During the Simulated Flood) 

 

3 Week Push In at 5 Days per Week 

Sand per Day 44,444 yd3

/day Assumes 15 days to push all of the sand in 

Push Rate 700 yd3

/hour Push rate @ 300ft avg. for a D10 dozer 

Yards per Day per Dozer 5600 yd3

/day 8 hour work day 

 D10 Dozers Needed 8 dozers 

 

3 Week Push In at 7 Days per Week 

Sand per Day 31,746 yd3

/day Assumes 21 days to push all of the sand in 

Push Rate 700 yd3

/hour Push rate @ 300ft avg. for a D10 dozer 

Yards per Day per Dozer 5600 yd3

/day 8 hour work day 

 D10 Dozers Needed 6 dozers 

 

3 Week Push In at 5 Days per Week 

Sand per Day 44,444 yd3

/day Assumes 15 days to push all of the sand in 

Push Rate 700 yd3

/hour Push rate @ 300ft avg. for a D10 dozer 

Yards per Day per Dozer 7000 yd3

/day 10 hour work day 

 D10 Dozers Needed 7 dozers 

 

3 Week Push In at 7 Days per Week 

Sand per Day 31,746 yd3

/day Assumes 21 days to push all of the sand in 

Push Rate 700 yd3

/hour Push rate @ 300ft avg. for a D10 dozer 

Yards per Day per Dozer 7000 yd3

/day 10 hour work day 

 D10 Dozers Needed 5 dozers