for the fabri dam prepared for modifications project · modifications project . flint, michigan ....

Conceptual Design Report for the

Fabri Dam Modifications Project

Flint, Michigan

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, PE Recreation

Engineering and Planning

485 Arapahoe Ave. Boulder, CO 80302

(303)545-5883

November, 2008

Recreation Engineering and Planning

485 Arapahoe Ave Boulder | CO | 80302

(303) 545-5883

Table of Contents

Introduction......................................................................................................................... 2

Background......................................................................................................................... 2

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

Project Description............................................................................................................ 12

Anticipated Use................................................................................................................. 16

Accessibility...................................................................................................................... 18

Maintenance...................................................................................................................... 18

Costs.................................................................................................................................. 18

Conclusion ........................................................................................................................ 21

Appendix 1. Conceptual Cost Estimate ........................................................................... 22

Appendix 2. Concept Plan ............................................................................................... 24



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SECTION 1:

INTRODUCTION



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Introduction

The Fabri Dam is located downstream from the Hamilton Dam. The structure is an

inflatable dam just west of the Grand Traverse Street Bridge. The original structure was

replaced in 2001 with an Obermeyer Hydro Inc. dam. Recreation Engineering and

Planning was contracted to create a conceptual design to replace this dam with structures

that provide a unique recreational whitewater opportunity in Flint. The purpose of this

project is to modify the current configuration of the dam, facilitate 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 the riparian environment at the site. 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 dangerous hazard 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 Fabri Dam on the Flint River in Flint, Michigan. The conceptual

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

improvements. The proposed improvements will create a whitewater paddling amenity

for the local community and a resource for the region. This site contains the physical

characteristics necessary to provide the proposed recreational improvements due to

gradient, flow, and its downtown location with existing associated infrastructure;

including parking, restrooms and access.

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.



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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

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 Clear Creek, Golden, 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.

Recreation Engineering and Planning 485 Arapahoe Ave

Boulder | CO | 80302 (303) 545-5883 5

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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SECTION 2:

SITE

DESCRIPTION

Fabri Dam

Project area

The project area is located at the existing Fabri Dam just downstream of Downtown Flint and the Hamilton Dam (source: www.earth.google.com).

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

Flint, Michigan. The Fabri Dam is located directly downstream from the University of

Michigan, Downtown Flint and the Hamilton Dam.

The precise amount of hydraulic head is variable however, site inspection has revealed

sufficient vertical fall for recreational improvements.



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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

Monthly-mean flows at the proposed project site from 1932 through 2007 Source:

http://waterdata.usgs.gov/nwis/monthly.)

Flows at the site vary from 1500 cubic feet per second (cfs) in the early spring to 250 cfs

in mid-summer to early fall. Extreme flood flows have historically reached above 15,000

cfs in the Flint River, however flows typically 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. 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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Peak streamflows at the proposed project site (source: waterdata.usgs.gov, station USGS 04148500

Flint River Near Flint, Michigan).



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SECTION 3:

PROJECT

DESCRIPTION

Project Description

Conceptual Design for Fabri Dam Modifications

A full-page version of this drawing is available in Appendix 2. This plan illustrates the

proposed layout of the suggested improvements at the Fabri Dam. The general layout

provides for five whitewater features located in the main channel of the river. Each

feature would consist of a drop structure with approximately one to two feet of head.

The first three structures would be located upstream of the existing dam and two drop

structures locate at and below the existing dam. The hydraulic fall redistributed through a

longer reach allowing for a more gradual transition along the Flint River. The existing

Obermeyer inflatable dam can be relocated upstream to the first drop structure. This will

allow control of the upstream water surface elevation and preserve the existing flat-water

amenity and aesthetics. A modular whitewater feature can be installed in concert with



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the relocated Obermeyer Dam to create an adjustable whitewater feature. Adjustability

will facilitate use by a wide cross section of recreational users.

The West Plains Diversion in Pueblo Colorado was modified for fish passage, safety and recreation in

2004.

Typical profile of a dam modification. The hydraulic fall is redistributed through a longer reach.



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Selective bank access improvements on both banks, including egress and ingress points

as well as seating areas and augmentation of existing trails, should also be included in the

project.

Bank and access improvements can improve safety, connect the public to the river and create

vibrancy in an urban core.



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SECTION 4:

ANTICIPATED

USE

Anticipated Use



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wer

This project will serve many users and purposes. The

site will be designed to be an attraction to recreational

users. The character of the features created by each of

the drop structures will evolve as the flow rates at the

site increase and decrease throughout the year. At lo

flows the 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 flows of over 1000 cfs the more powerful

whitewater features will create a regional draw for intermediate and expert users while

not preventing the use of the project by inexperienced users.

Paddlers at the Pueblo Whitewater Park

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.

Whitewater Parks can provide diverse experiences along rivers.



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SECTION 5:

ACCESSABILITY

SECTION 6:

MAINTENANCE

SECTION 7:

COSTS

Accessibility

The site is immediately accessible through the existing

downtown area and trails. Access points would be

constructed both upstream and downstream of the

whitewater features to allow for ingress and egress to

and from the river.

Maintenance

In-stream improvements are virtually maintenance-free

following the first year. 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 banks and adjacent park

areas 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.



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SECTION 8:

FUTURE WORK

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

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.

Boulder Creek



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SECTION 9:

CONCLUSION

Before and After in the Salida, Colorado Whitewater Park



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Conclusion

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

These improvements will remove an existing hazard as well as provide a recreational

amenity that will attract recreational users and their families from the region to

downtown Flint. The proposed improvements will preserve the base of the existing dam

while redistributing the head through a longer reach of the Flint River. The hydraulics

formed by the whitewater structures will be user friendly and are not intended to create

hazardous conditions for inexperienced users. Many communities have found that

whitewater parks not only provide solutions to 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 Fabri Dam.

Appendix 1. Conceptual Cost Estimate



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0

00

00

00

00

00

Item # DescriptionEstimated Quantity Unit Unit Price

Item Total Price

1 Mobilization L.S. L.S. $50,000 $50,00

2

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

L.S. L.S. $260,000 $260,000

3

Demo/remove existing Obermeyer Gates-leave concrete abutment walls and concrete base.

L.S. L.S. $160,000 $160,000

4Grouted rock drop structures:

4A (Drop #1)

reconfigured Obermeyer gate, with grouted rock abutments

L.S.

cubic yards grouted rock & reconfiguration of Obermeyer

L.S. $215,000

4B

Drop # 2

1,300 cubic yards grouted rock $180 $234,0

4C Drop # 3 1,300 cubic yards grouted rock $180 $234,0

4DDrop #4-At Dam Face 600 cubic yards

grouted rock $180 $108,0

4E Drop #5 1,000 cubic yards grouted rock $180 $180,0

5Offset Current Deflectors (4) 1,200 cubic yards

grouted rock $180 $216,0

Flint Michigan-Fabri Dam Cost Estimate11/4/2008



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0

0

6Boulder edge and terracing 3,500 LF $160 $560,000

7Large Random Boulders 40 L.S. $400 $16,00

8 miscellaneous heavy Equipment cost/hour

300 hours $180 $54,00

9

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

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

$2,527,000

10 Contingency 25% $631,750

11Design and Permitting 16% $404,320

$3,563,070

$180 $180 $400

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

Subtotal

Total



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Appendix 2. Concept Plan



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