proposal to construct

Prepared For:

City of Flint P.O. Box 99

Flint, MI 48501-0099

Flint River Watershed Coalition

432 N. Saginaw St. Suite 1001

Flint MI 48502

Prepared By:

Gary M. Lacy, P.E. Recreation

Engineering and Planning

485 Arapahoe Ave. Boulder, CO 80302

(303) 545-5883

Conceptual Design Report for the

Hamilton Dam Modifications Project

Flint, Michigan

November, 2008

Recreation Engineering and Planning

485 Arapahoe Ave Boulder | CO | 80302

(303) 545-5883

Table of Contents Introduction..................................................................................................................................... 1

Background..................................................................................................................................... 3

Economic Benefit............................................................................................................................ 6

Site Description............................................................................................................................... 7

Project Description........................................................................................................................ 11

Anticipated Use............................................................................................................................. 13

Accessibility.................................................................................................................................. 14

Maintenance.................................................................................................................................. 15

Costs.............................................................................................................................................. 15

Future Work .................................................................................................................................. 15

Conclusion .................................................................................................................................... 16

Appendix 1. Conceptual Cost Estimate ....................................................................................... 17

Appendix 2. Concept Plan ........................................................................................................... 19



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Introduction

Built in 1920, the Hamilton Dam is located on the Flint River as it flows through the City

of Flint, Michigan. It once served not only as a dam, but a pedestrian bridge as well.

Today, however, this river-wide dam obstructs the river’s flow, presents dangerous

structural weaknesses and is a threat to public safety. Because of this current state of

disrepair, the Michigan Department of Environmental Quality has mandated the

Hamilton Dam be replaced. Recreation Engineering and Planning was contracted to

create a conceptual design for such replacement that would provide a unique recreational

whitewater opportunity in Flint.

The purpose of this project is to replace the current dam with a structurally and

hydraulically sound structure that maintains adequate upstream pool elevation, allows for

the City of Flint to pump water for a backup water system, maintain adequate bank head

pressure to not allow contaminates into the river, provide reasonable fish passage, and

provide a recreational amenity. Similar dams in cities across the country have been

converted to provide attractive recreational amenities while improving safety and

maintaining the purpose of the dam. The resulting improvements not only provide for

increased safety in the river, but serve as an attraction to residents and visitors who seek

whitewater for recreation, events, and competition. The net effect of such improvements

results in transforming a failing dam into a popular community attraction that stimulates

the local economy.

This report presents a conceptual plan and cost estimate for the construction of

improvements to the Hamilton Dam on the Flint River in Flint, Michigan. The

conceptual plan consists of recreational boating improvements as well as related bank and



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access improvements. The proposed improvements will create a whitewater paddling

amenity for the local community and a resource for the region. The site is ideal due to

the amount of available gradient, flow and its location adjacent to the University and

downtown area. Adjacent infrastructure including parking, restrooms, lodging and

restaurants help make this site an outstanding location for this project.



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Background

Many communities across North America are looking to their river corridors, historically

centers of industry, as the heart of urban renewal plans. Rivers can serve as the catalyst

for economic development, and as the dominant natural feature of communities,

accessible river corridors with recreational amenities are key anchors. Whitewater Parks

and Courses are increasingly being explored and built by communities looking to create a

unique attraction and recreational opportunity of national importance.

The term “whitewater park” is analogous to a brand name that has been generally applied

to river access improvement projects all over the US. These projects are located in

diverse communities, with diverse goals. The common thread among all of these projects

is that elements of a public river corridor had become a liability. Whitewater parks

convert river corridors and failing dams from liabilities, to amenities that provide

recreational opportunities and economic stimulus.

Whitewater parks are an emerging trend in North America that provides river related

recreation near a population center. Whitewater parks vary in length from the longest, 1

mile, to the shortest, 1 single feature, but all meet the same goal: attracting diverse users

to a single destination where they can recreate without the logistical issues involved in

more traditional, point A to point B river trips.

These parks can be constructed in all types of rivers and can be designed to achieve a

range of different outcomes. In-stream modification, as seen in the Salida Whitewater

Park, consists of a feature created with carefully placed, native boulders within the

existing channel. The appropriateness of this type of improvement is based on the



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availability of flow, the gradient of the stream in the immediate vicinity of the drop

structure, and the geotechnical makeup of the substrata of the river.

In-stream whitewater improvements are popular in appropriate rivers around the western US. This

structure is located in the Arkansas River in Salida, Colorado.

Dam modification whitewater parks are also a commonly pursued option, whereby an

existing dam is retrofitted with drop structures to create a whitewater course on the

backside of a dam. Dam modifications, like the Rio Vista Dam shown in the photo

below, serve to eliminate structural stability issues and mitigate existing navigability

hazards while maintaining the existing use of the dam and not negatively impacting the

floodplain. These projects are appropriate when a dam’s function needs to be maintained

but the downstream edge of the dam can be modified for navigation, recreation and fish

passage, or when the crest of a dam can be lowered and the vertical fall of the dam can be

redistributed through a longer reach.



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This whitewater park in San Marcos, Texas is an example of a dam modification project. The original crest of this dam and its diversion capabilities are maintained while the vertical drop on the back side of the dam is redistributed in a drop/pool sequence.

Diverse communities ranging in population and geographic characteristics are turning to

their rivers as a source of recreation, education, and local pride. Whitewater parks attract

citizens of all ages and socio-economic backgrounds. The operation of these parks across

the country has shown that these types of projects provide a number of benefits including

new recreational opportunities, economic stimulus, enhanced aquatic habitat and

environmental education opportunities.



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Economic Benefit

There is substantial, empirical evidence that river access improvements can have

significant, positive, economic benefits, for a local community. Whitewater Parks attract

a desirable demographic of users between the ages of 25-45 with disposable income and

the willingness to travel in pursuit of this specific recreational activity. Golden, Colorado

commissioned an economic impact study in the year 2000 for a whitewater park that was

built in 1996. At the time of the study, the project was shown to have an annual

economic impact of between $1.4million-$2million to the local community. This study

was for a stream which has a usable season of three months. The whitewater park in

Reno, Nevada has a projected economic impact of $18million over the first decade and

contributes to a $9million economic impact of the, annual, three day, Reno River

Festival.

The Truckee River Whitewater Park at Wingfield, Reno Nevada.



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Site Description

Flint River and

Hamilton Dam Project

Hamilton Dam project site. (Source Google Earth)

The location for improvements is at the existing Hamilton Dam located on the Flint River

in Flint, Michigan. Due to the site’s location adjacent to the University of Michigan and

Downtown Flint, it is expected to attract a diverse number of users.



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As built drawings of the existing Hamilton Dam. (Source US Army Corps of Engineers.)



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Monthly Mean Streamflow: USGS 04148500 Flint River near Flint, MI from 1932-2007

0

500

1000

1500

2000

Jan

Feb

Mar

Apr

May Ju

n

Jul

Aug

Sep Oct

Nov

Dec

month

cfs

Mean-monthly flows at the proposed project site from October, 1926 through September, 1960. (source: http://waterdata.usgs.gov/nwis/monthly.)

Flows at the site vary from around 1500 cubic feet per second (cfs) in the early spring,

down to around 250 cfs in mid-summer to early fall. Peak streamflow data is shown in

Error! Reference source not found.. Extreme flood flows have historically reached

above 15,000 cfs in the Flint River. However, flows usually peak in the range of 4,000

cfs.

This historic flow data suggests that the project would be useable 12 months a year,

weather permitting. The most popular seasons for usage would during the spring and

summer months. Use of similar projects typically follows the hydrograph. When flows

are higher more experienced users will use the facility; when flows are lower during the

summer months less experienced users and bank-based users will frequent the site.



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Historical peak streamflows at the proposed project site (source: waterdata.usgs.gov, station USGS 04148500 Flint River Near Flint, Michigan.)



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Project Description

Conceptual Plan for the proposed improvements at Hamilton Dam.

This plan illustrates the proposed layout of the suggested improvements at the Hamilton

Dam. A full-page version of this drawing is available in Appendix 1. The general layout

provides for three whitewater features/grade control structures located in the main

channel of the river adjacent to the University. Each feature would consist of a drop

structure with approximately two feet of head. The first structure will be located at the

existing dam, with the crest being approximately two feet lower than the existing crest.

The final two structures will be located downstream from the existing dam, upstream of

the Harrison Street Bridge.



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Typical profile view of a low-head dam modified for fish passage and safety.

The crest of this low head dam was similarly modified for safe passage.

A new pedestrian bridge would be constructed at the location of the dam, with trail

extensions to connect the park on river right with existing trails on river left. Selective

bank access improvements and bank terracing will be included on both banks between

the dam and the Harrison Street Bridge. This terracing will provide safe river access and

improve public safety while maintaining existing flood protection.



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Completed bank terracing at Reach of the Flint River that the Truckee Whitewater Park in Reno, NV. would benefit from bank terracing.

Anticipated Use

This project will serve many users and

purposes. The primary purpose of the

modifications is to replace the aging and

deteriorating dam with a structurally and

hydraulically sound structure.

Additionally, the site will be designed as an

attraction to whitewater enthusiasts such a

kayakers, canoeists and rafters. The

character of the features created by e

the drop structures will evolve as the flow

rates at the site increase and decrease

throughout the year. At lower flows th

park will provide recreation opportunities for less experienced river users as well as

intermediate and expert users who come to the site for fitness and practice. At higher

s

ach of

e Paddlers at the Pueblo Whitewater Park



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flows of over 1000 cfs the more powerful whitewater features will create a regio

for intermediate and expert users while still allowing use of the project by inexperienc

users.

nal draw

ed

The design can also accommodate upstream fish passage. Future design phases will need

to consider the specific needs of critical local fish species. Generally, the proposed grade

control structures can provide short sections of both higher velocity flow and velocity

shelters to facilitate upstream fish movement.

Accessibility

The site is immediately accessible through the University of Michigan-Flint campus and

the downtown area. Access points would be constructed both upstream and downstream

of the whitewater features to allow for ingress and egress to and from the river.



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Maintenance

In-stream improvements are virtually maintenance-free. Regular inspections should be

scheduled to evaluate any significant erosion during the first year and every year

thereafter. Tree, ice and woody debris will be passed in the course of normal flows, but

should be removed if suspended during high-use times as they represent an immediate in-

stream hazard. Maintenance of the existing park will require typical park maintenance

for parking areas, restrooms, etc.

Costs

See the attached cost estimate. Normally, the bulk of this cost is in construction of in-

channel improvements. In-stream drops and pools should be constructed, along with any

related paths/ access ways, during low-flow periods. Reduction in rock costs through

donated or stored rock can have a significant impact on the total cost of the project.

Future Work

If the City decides to go forward with this project, future tasks include but are not

necessarily limited to:

• Detail Design

• Flood/Fluid Modeling

• Permit Applications

• Construction and Bid Documents

• Construction Phase Services

These tasks are categorized in Design and Construction Phase Services, as listed in the

attached cost estimate. It is recommended that the design team open a dialogue with



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related planning and government agencies as soon as possible following the decision to

proceed, as it is often imperative that these stakeholders be included in the design

process.

Conclusion

Cost effective, recreational safety improvements can be made at the Hamilton Dam site.

These improvements will provide a solution to the structural stability concerns at the

Hamilton Dam, remove an existing hazard and provide a recreational amenity that will

attract recreational users and their families throughout the region, to Flint. The proposed

improvements will preserve the base of the existing dam while gradually redistributing

the vertical fall to eliminate the existing powerful hydraulic. The hydraulics formed by

the whitewater structures will be user friendly and will not act to keep inexperienced

boaters or users of inflatable craft trapped. Many communities have found that

whitewater parks not only solve safety issues, but also draw residents as well as visitors

to the river, thus providing an economic driver for the local community. . Similar

improvements have had enormous impacts on the quality of life and local economies of

communities throughout the country. REP’s $170,000 whitewater park in Golden,

Colorado has had an estimated 1.7 to 2 million dollar per year impact on the local

economy. Similar estimates have been made for our parks in Breckenridge and Vail.

Another project, a two-channel whitewater park on the Truckee River at Wingfield Island

in Reno, Nevada, has transformed a neglected and denuded section of downtown into a

revitalized urban greenway with walking paths, shaded riverside seating, and picnic areas

all surrounded by world-class whitewater. Just like the cities mentioned above, Flint has

the potential to create a world-class recreational amenity that could benefit the entire

community. For these reasons REP recommends including recreational improvements in

the modification of the Hamilton Dam.



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Appendix 1. Conceptual Cost Estimate

Item # Description Estimated Quantity Unit Unit PriceItem Total

Price

1 Mobilization L.S. L.S. $50,000 $50,0

2

Dewater (During low-flow) open obermyer gates, construct coffer dams and area pumping.

L.S. L.S. $240,000 $240,000

3

Demo existing Bridge/Dam super structure and Gates

00

-leave concrete abutment walls and ogee crest.

L.S. L.S. $140,000 $140,000

4Grouted rock drop structures:

4A

At Dam Face

1,100cubic yards

grouted rock

$190 $209,00

4B

Drop # 2

1,600cubic yards

grouted rock

$190 $304,00

4C

Drop # 3

1,000cubic yards

grouted rock

$190 $190,00

5Boulder edge and terracing 1,400 LF $160 $224,000

6Large Random Boulders 20 L.S. $400 $8,000

Flint Michigan-Hamilton Dam Cost Estimate

0

0

0

11/3/2008



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7miscellaneous heavy Equipment cost/hour

240 hours $180 $43,2

8

landscape restoration and miscellaneous signage, put-ins, take-outs and trails

L.S. hours $90,000 $90,0

$1,498,200

9 Contingency 25% $374,550

10Design and Permitting 16% $239,712

$2,112,462

11Pedestrain Bridge replacement L.S. $200,000

$190 $180 $400

Itemized costs:Grouted Rock costs per cubic yardHeavy equipment cost/hourLarge Random Boulders

Subtotal

Total

00

00



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Appendix 2. Concept Plan



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