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. Boulder, CO 80302 (303)545-5883 November, 2008
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 (303) 545-5883
SECTION 1: INTRODUCTION (303) 545-5883 1
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. (303) 545-5883 2
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. (303) 545-5883 3
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. (303) 545-5883 4
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. (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. (303) 545-5883 6
SECTION 2: SITE DESCRIPTION (303) 545-5883 7
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. (303) 545-5883 8
Monthly Mean Streamflow: USGS 04148500 Flint River near Flint, MI from 1932-2007 2000 1500 1000 500 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec cfs month 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. (303) 545-5883 9
Peak streamflows at the proposed project site (source: waterdata.usgs.gov, station USGS 04148500 Flint River Near Flint, Michigan). (303) 545-5883 10
SECTION 3: PROJECT DESCRIPTION (303) 545-5883 11
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 (303) 545-5883 12
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. (303) 545-5883 13
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. (303) 545-5883 14
SECTION 4: ANTICIPATED USE (303) 545-5883 15
Anticipated Use 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 lower flows the park will provide recreation opportunities for less experienced river users as well as intermediate and Paddlers at the Pueblo expert users who come to the site for fitness and practice. Whitewater Park 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. 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. (303) 545-5883 16
Whitewater Parks can provide diverse experiences along rivers. (303) 545-5883 17
SECTION 5: ACCESSABILITY SECTION 6: MAINTENANCE SECTION 7: 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. COSTS (303) 545-5883 18
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 SECTION 8: 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 FUTURE WORK (303) 545-5883 19
SECTION 9: Before and After in the Salida, Colorado Whitewater Park CONCLUSION (303) 545-5883 20
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. (303) 545-5883 21
Appendix 1. Conceptual Cost Estimate Item # Description Flint Michigan-Fabri Dam Cost Estimate 11/4/2008 Estimated Quantity Unit Unit Price Item Total Price 1 Mobilization L.S. L.S. $50,000 $50,000 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 4 Grouted 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 1,300 cubic yards grouted rock $180 $234,000 Drop # 2 4C 4D 4E Drop # 3 Drop #4-At Dam Face Drop #5 1,300 600 1,000 cubic yards grouted rock cubic yards grouted rock cubic yards grouted rock $180 $234,000 $180 $108,000 $180 $180,000 5 Offset Current Deflectors (4) 1,200 cubic yards grouted rock $180 $216,000 (303) 545-5883 22
6 Boulder edge and terracing 3,500 LF $160 $560,000 7 Large Random Boulders 40 L.S. $400 $16,000 8 miscellaneous heavy Equipment cost/hour 300 hours $180 $54,000 9 landscape restoration and miscellaneous signage, put-ins, take-outs and trails L.S. hours $240,000 $240,000 Subtotal $2,527,000 10 Contingency 25% $631,750 11 Design and Permitting 16% $404,320 Total $3,563,070 Itemized costs: Grouted Rock costs per cubic yard Heavy equipment cost/hour Large Random Boulders $180 $180 $400 (303) 545-5883 23
Appendix 2. Concept Plan (303) 545-5883 24
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