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HomeMy Public PortalAbout2013 Flood Protection Study - Section 3-4 Section 3 Flood Protection Technologies and Technology Evaluation This evaluation consisted of a brief review of various technologies available for flood protection. The review focused on five flood protection technologies. The goal of this evaluation was to provide a basis for the recommended flood protection system for the City. 3.1 Flood Protection Technologies Considerations The evaluation of flood protection technologies used the following considerations (parameters): effectiveness, constructability, cost/affordability, preliminary alignment constraints, and maintenance and storage requirements. Additional points of considerations included equipment, people and time requirements for installation, response planning, safety, and servicing the system under potentially prolonged flood conditions. 3.1.1 Aspects Considered Specific aspects considered for each of the flood protection technologies included:  Effectiveness - Length of time to set up the system (how much warning time is needed) - Function of the system during extended flood events (durability)  Constructability - Labor requirements for installation (ease of constructability) - Special equipment requirements for installation  Affordability - Cost of system per linear foot of alignment - Initial and recurring costs  Alignment Constraints - Foundation requirements - Available area for installation (width and height) - Existing utility impacts 3-1 Section 3 Flood Protection Technologies and Technology Evaluation.docx Section 3 • Flood Protection Technologies and Technology Evaluation  Maintenance and storage - Inspection and maintenance requirements during extended flood conditions - Maintenance requirements during non- and post flood conditions 3.1.2 Aspects Not Considered The evaluation of flood protection technologies did not consider the following information:  Potential relocation of existing utilities  Geotechnical design for any foundations or embankments  Hydrologic and hydraulic analysis of the drainage area to each study area  FEMA floodway analysis  Under seepage protection or permanent pump stations  Required right-of-way or easement acquisitions  Temporary technologies supplemental costs, including shipping and labor to install 3.1.3 Flood Protection Technologies The types of flood protection systems evaluated included permanent, temporary, and combined system solutions. The evaluated flood protection technologies include:  Concrete walls  Fabric membrane dams  Metal panels  Water-inflated tubes  Water-inflated baffled bladders 3.2 Evaluation Parameters The evaluation process consisted of determining preliminary physical constraints found in the study areas. Specific constraints included minimum width availability as relates to proposed flood protection alignment and estimated existing ground surface elevation along proposed flood protection alignment. Additionally, the various technologies were reviewed utilizing standards listed in the scope of work, standards found in the USACE Flood Technology Test Report (Test Report), interviews with USACE flood fighting staff, interviews with flood protection technology vendors, and through Internet research. 3.2.1 Determination of Flood Protection Height and Width Height Determination The height of flood protection for the Downtown area was determined using the difference between the base flood elevation and ground elevation. This difference varies along the flood protection 3-2 Section 3 Flood Protection Technologies and Technology Evaluation.docx Section 3 • Flood Protection Technologies and Technology Evaluation alignment. The Missouri River base flood elevation (1-Percent Annual Chance Flood) of 760 feet is from the preliminary D-FIRM as shown on Figure 3-1 and on the preliminary profile as shown by the red dashed line crossing the solid red line on Figure 3-2. The preliminary D-FIRM indicates that the Downtown study area is within an AE Zone. FEMA defines an AE Zone as an area subject to inundation by the 1-Percent Annual Chance Flood event with base flood elevations shown (44 CFR 64.3 (a) (1) AE: area of special flood hazard with water surface elevation (WSE) determined). The height of flood protection for the Park was determined using the difference between the 10-Percent Annual Chance Flood elevation (as shown at the blue dashed line crossing the solid red line on Figure 3-2), or 752 feet, and the ground elevation, an average of 746 feet. The preliminary D-FIRM indicates that the entire Park is within an AE Zone, as shown on Figure 3-1. Additionally the majority of the Park is located within a defined floodway, also shown on Figure 3-1. Preliminary D-FIRM data was determined to be the most appropriate for all flood technology evaluation and for recommendations. If the preliminary D-FIRMs do not become effective, the effective based flood elevation for the Missouri River is 762 feet. A comparison of the elevation contours and the November 2012 City provided survey points found the survey point recorded at the low water bridge in the northwest corner of the park was within 0.07 of a foot of the contour line elevation. The level of accuracy of the elevation contours was determined acceptable for the conceptual level of this study; therefore, the elevation contours provided an estimate of the ground elevation throughout the study area. Width Determination Width constraints affect flood protection of both the Downtown and the Park. The Downtown study area is a commercial use area with various businesses. Therefore, vehicular and pedestrian access, location of existing buildings, and location of existing utilities, including an active railroad, restrict the available width for flood protection construction and implementation. In the Park, the location of large, mature trees, and the banks of the Missouri River and White Aloe Branch affect construction of any flood protection technology. Key width constraints include:  Downtown Study Area: - Limited width between White Aloe Branch and the U.S. Post Office Building (approximately 8 feet). - Limited width between railroad and buildings (approximately 14 feet).  Park Study Area: - Limited width between the large mature trees and the bank of the Missouri River (average 37 feet). 3.2.2 Review Federal Design Standard Flood protection installed in each study area must meet local, state, and Federal design criteria, including USACE and FEMA design standards. For the flood protection evaluation, the USACE Test Report provided flood protection evaluation criteria. In the USACE Test Report, the USACE tested three of the available flood protection technologies: Rapid Deployment Flood Wall (plastic grid device and granular material), Portadam (fabric dam) and Hesco Bastion Concertainer (geotextile lined metal mesh container and granular material). 3-3 Section 3 Flood Protection Technologies and Technology Evaluation.docx E 3rd Street E 2nd Street E 1st Stree t Mill Stree t Ma i n S t r e e t Ea s t S t r e e t Engl i s h L a n d i n g D r i v e UV9 Whi t e A l o e B r a n c h Rush Creek Missouri River 76 0 760 760 Base Flood Elevation Cross Section Preliminary Zone AE Preliminary Floodway Waterway (c) 2010 Microsoft Corporation and its data suppliers Figure 3-1 Preliminary Floodplain and Floodway (SEMA, March 2012) . Figure 3-2 Preliminary Flood Profile for Missouri River (SEMA, March 2012) Cross Section of Missouri River near White Aloe Branch 1% Annual Chance Flood Water Surface Elevation at Study Area 10% Annual Chance Flood Water Surface Elevation at Study Area Section 3 • Flood Protection Technologies and Technology Evaluation The review for this study utilized some of the USACE Test Report’s evaluation, such as the possibility of puncture and leakage, and constructability. The FEMA design standards include a freeboard requirement for base flood protection. The height of FEMA flood design flood protection is based on the base flood elevation and the permanent flood levee protection regulations as found in 44 CFR 65.10 (b) (1) Freeboard (Table 3-1). Table 3-1 FEMA Freeboard Requirements 1 Type Description Minimum freeboard 2 Three feet above base flood elevation Freeboard either side of structure (such as bridge) An additional one foot for a distance of 100 feet on either side of structure Upstream end of levee An additional one-half foot starting at upstream end of levee system tapering to minimum at the downstream end 1 Source 44 CFR 65.10 (b) (1) 2 Exceptions may be approved after appropriate and approved engineering analysis, however freeboard less than 2 feet is unacceptable per 44 CFR 65.10 (b) (1) (ii). 3.2.3 Interview Comments USACE flood fighters and flood protection vendors provided their comments on the practical use of each technology. These comments provide a real-world perspective on the use of these flood protection technologies. Some of their comments included:  Stop logs (metal panel flood protection) have some seepage.  Most fabric membrane (including dams and water-inflated options) does not last as long as advertised due to weakened spots from exposure to elements and along fold lines from storage.  Storing of the temporary fabric technology is more labor intensive. It requires thorough cleaning and proper folding to prevent rot and weakening of fabric.  Wind effects fabric technology during set-up and prior to flood waters holding the fabric in place.  It is important to practice installing temporary technologies. The installation process can be difficult to implement during an emergency due to panic, stress, etc. that can affect human reactions.  Technologies with multiple pieces can suffer from loss/misplace of system pieces. 3.2.4 Internet Research Results Material retrieved from the Internet included vendor contact information, product specifications, photos, and installation locations. This information is provided in Appendix A. 3.3 Evaluation of Technologies This section evaluates each flood protection technology using the parameters defined in Sub-Section 3.2. The following tables present advantages and disadvantages related to these parameters, more specifically to the installation, maintenance, and cost for each respective flood protection technology. 3-6 Section 3 Flood Protection Technologies and Technology Evaluation.docx Section 3 • Flood Protection Technologies and Technology Evaluation 3.3.1 Concrete Walls The use of concrete walls is a permanent flood protection technology as shown on Figure 3-3. Table 3-2 lists the advantages and disadvantages of using a concrete wall for flood protection. Figure 3-3 Concrete Floodwall (Photo Source: CDM Smith) Table 3-2 Concrete Floodwalls Advantages and Disadvantages Parameter Advantages Disadvantages Maintenance  Reduces long-term maintenance (annual inspection may be required)  Limits dry side drainage  Potential for graffiti Installation  Requires minimal base width  Reduces time needed for flood fighting effort versus temporary efforts  Can be built in any configuration  Permanent protection (possibly lead to LOMR)1  Requires adequate space for construction Cost  Reduces long-term maintenance cost  No storage costs  No repeated installation costs  Initial installation more expensive 1 For a fee, a Letter of Map Revision (LOMR) is a procedure offered by FEMA that changes the Special Flood Hazard Area (SFHA) based on revised hydrology and hydraulics. 3-7 Section 3 Flood Protection Technologies and Technology Evaluation.docx Section 3 • Flood Protection Technologies and Technology Evaluation 3.3.2 Fabric Membrane Dams The use of fabric membrane dams is a temporary flood protection technology as shown on Figure 3-4. Table 3-3 lists the advantages and disadvantages of using fabric membrane dams for flood protection. The City utilized this temporary flood protection technology for the Downtown study area in 2011. Figure 3-4 Fabric Membrane Dam Flood Protection (Photo Source: Portadam) Table 3-3 Fabric Membrane Dam Advantages and Disadvantages Parameter Advantages Disadvantages Maintenance  City personnel familiar with maintenance process from 2011 experience  Can be punctured  Must be continually inspected during operation  Must be thoroughly cleaned prior to storage after each use Installation  City personnel familiar with installation process  1/10th the weight of standard sandbags  Does not require permanent foundation  Does not require prepared surface  Can be installed in any configuration  Requires sandbag supplementation  Wind effects (until weight of floodwater stabilizes)  Equipment required to move pallets of material to installation spots Cost N/A  Most expensive of the fabric flood protection technologies (material cost) 3-8 Section 3 Flood Protection Technologies and Technology Evaluation.docx Section 3 • Flood Protection Technologies and Technology Evaluation 3.3.3 Metal Panels The use of metal panels is a temporary flood protection technology with a permanent footer as shown on Figure 3-5. Metal panels are also usable as a mixed technology with the use of a permanent stem-wall. Table 3-4 lists the advantages and disadvantages of using metal panels for flood protection. Figure 3-5 Metal Panel Flood Protection (Photo Source: EKO Flood Systems USA, LLC) Table 3-4 Metal Panel Advantages and Disadvantages Parameter Advantages Disadvantages Maintenance  Minimal maintenance − Easily stored (stackable)  Must be cleaned with pressure washer after each use Installation  Quick Installation (Example: 1 person can install 1,000 square feet in 5 hours)  Multiple configuration options (footer and stemwall)  Greater height does not require a greater above surface base width  Can be used with permanent stem wall (reduces time needed for installation of flood protection)  Seepage occurs  Equipment required to move pallets of material to installation spots  Requires permanent footer − Size of footer dependent upon soil structure and wall height − Requires adequate space for initial construction of footer Cost  Additional panels can be purchased in future to increase height of flood protection  Most expensive of temporary applications 3-9 Section 3 Flood Protection Technologies and Technology Evaluation.docx Section 3 • Flood Protection Technologies and Technology Evaluation 3.3.4 Water-Inflated Tubes The use of water-inflated tubes is a temporary flood protection technology as shown on Figure 3-6. Table 3-5 lists the advantages and disadvantages of using water-inflated tubes for flood protection. Figure 3-6 Water-Inflated Tubes at Testing Grounds (Photo Source: US Flood Control Corporation) Table 3-5 Water-Inflated Tubes Advantages and Disadvantages Parameter Advantages Disadvantages Maintenance  Can withstand up to 2,680 pounds of lateral pressure (depending on anchor diameter)1  Punctures do not necessarily result in loss of flood protection  Must be thoroughly cleaned prior to storage after each use  Can be punctured  Must be continually inspected during operation Installation  Quick installation  Stackable (to achieve greater height)  Can be installed in many configurations  Does not require permanent foundation  Greater height requires a wider base (approximate 1V:1H due to interlocking of tubes as shown in Figure 3-7)  Equipment required to move pallets of material to installation spots  Limited turning radius Cost  Least expensive of reviewed flood protection N/A 1 Wenck Associates, Inc. Review of the Tiger Dam System Technical Memorandum dated March 22, 2010. WWaatteerr--IInnffllaatteedd TTuubbeess Figure 3-7 Water-Inflated Tubes Dimension Cross Section Ground Sheet 3-10 Section 3 Flood Protection Technologies and Technology Evaluation.docx Section 3 • Flood Protection Technologies and Technology Evaluation 3.3.5 Water-Inflated Baffled Bladders The use of water-inflated baffled bladders is a temporary flood protection technology as shown on Figure 3-8. Table 3-6 lists the advantages and disadvantages of using water-inflated baffled bladders for flood protection. Figure 3-8 Water-Inflated Baffled Bladder (Photo Source: Hydrological Solutions, Inc.) Table 3-6 Water-Inflated Baffled Bladders Advantages and Disadvantages Parameter Advantages Disadvantages Maintenance  Limited maintenance during installation  Can be punctured  Must be continually inspected during operation  Must be thoroughly cleaned prior to storage after each use Installation  Quick installation  Stable (will not roll)  Does not require permanent foundation  Greater height requires a wider base (1V:2.25H)  Limited height (protects up to 6-foot WSE)  Limited configuration (Does not bend like water-inflated tubes)  Not stackable  Equipment required to move pallets of material to installation spots Cost N/A N/A 3-11 Section 3 Flood Protection Technologies and Technology Evaluation.docx Section 3 • Flood Protection Technologies and Technology Evaluation This page intentionally left blank 3-12 Section 3 Flood Protection Technologies and Technology Evaluation.docx Section 4 Flood Protection Plan and Cost Estimate for Downtown Parkville The level of flood protection for Downtown Parkville is the maximum achievable within the constraints of the desirable and maximum allowable height of barrier (aesthetics and flood protection technology constraints), available project base width for installation, desired alignment, affordability by the City, compliance with FEMA floodplain regulations, interior stormwater drainage, and other utilities considerations. As such, the level of protection evaluated for Downtown was the base flood elevation (commonly referred to as the 100-Year flood or 1-Percent Annual Chance Flood). 4.1 Downtown Parkville Flood Protection Alignment During the October 5, 2012 project progress meeting, the City stated that they have evaluated flood protection access to the businesses located south of the BNSF tracks. Therefore, this area was not considered in the recommendation for the Downtown study area. Figure 4-1 shows the City’s preferred flood protection alignment for the Downtown. The flood protection alignment runs along the west side of White Aloe Creek to the north side of the BNSF tracks, then westerly along the tracks. This alignment was used to determine physical parameters for flood protection, such as ground surface elevation and available space for installation. According to the elevation contours and the November 2012 survey provided by the City the ground surface elevation varies between 754 feet and 756 feet along the preferred flood protection alignment. Data provided by the City indicates that the proposed flood protection alignment for the Downtown has at least three areas that cross over sanitary sewer lines and at least three areas that cross over stormwater lines as shown in Figure 4-1. 4.2 Determination of Recommended Downtown Flood Protection Technology The recommended flood protection technology for the Downtown area was based on an evaluation of three parameters: maintenance, installation, and cost. 4.2.1 Flood Protection Technology Maintenance In order to determine the recommended flood protection technology, the types of maintenance requirements associated with the different flood protection technologies was researched and compared. The concrete floodwall had the least long-term maintenance concerns, as cleaning requirements are related to aesthetics, versus specific cleaning requirement that are required post-flood for all of the temporary technologies. The fabric membrane technologies and the metal panel system require frequent inspection to identify possible puncturing of the fabric or seepage in a metal panel system. To reduce chances of rotting and cracking fabric membranes, water-inflated tubes, and water-inflated baffled bladders require more thorough cleaning of the flood protection material and specific folding requirements for long-term storages. 4-1 Section 4 Flood Protection Plan & Cost Estimate for Downtown Parkville.docx E 3rd Street E 2nd Street E 1st Str e e t Mill Stree t Ma i n S t r e e t Ea s t S t r e e t Engl i s h L a n d i n g D r i v e UV9 Whi t e A l o e B r a n c h Sanitary Sewer Crossing Stormwater Crossing Downtown Flood Protection Alignment Stormwater Sewer Waterway 0 100 20050 Feet Figure 4-1 City Preferred Flood Protection Alignment and Sewer and Stormwater Utility Line Crossings . (c) 2010 Microsoft Corporation and its data suppliers Section 4 • Flood Protection Plan and Cost Estimate for Downtown Parkville 4.2.2 Flood Protection Technology Installation Installation criteria were based on both the flood protection height and associated required width for installation along the preferred flood protection alignment. In order to establish the flood protection height needed to provide protection from the base flood elevation, the height of flood protection was estimated. The estimated flood protection height was based on the preliminary base flood elevation, the current ground surface elevation of the proposed flood protection alignment, and the permanent flood levee protection regulations as found in 44 CFR 65.10 (b) (1) Freeboard and described in Table 3-1. The height of the flood protection vary along the preferred alignment due to the varying ground surface elevation and FEMA freeboard regulations (Table 3-1). Figure 4-2 shows sections of the alignment based on this varying ground surface. Table 4-1 relates the approximate required height of the flood protection in each of these sections. Table 4-1 Downtown Flood Protection Heights including Freeboard Requirements Flood Protection Approximate Height (ft) 1 Approximate Length (ft) FEMA Freeboard Requirements 2 Section 1 7.5 218 Upstream end of levee, minimum freeboard Section 2 7 157 Minimum freeboard Section 3 7 238 Minimum freeboard Section 4 8 106 Freeboard either side of structure (such as bridge), minimum freeboard Section 5 10 100 Freeboard either side of structure (such as bridge), minimum freeboard Section 6 9 516 Minimum freeboard Road Crossing 1 7 83 Minimum freeboard Road Crossing 2 7 43 Minimum freeboard Road Crossing 3 10 64 Freeboard either side of structure (such as bridge), Minimum freeboard 1 Approximate height based on estimated ground elevation along preferred flood protection alignment and the preliminary base flood elevation of 760 feet 2 As described in Table 3-1 Specific benefits were found related to installation of each technology and also in meeting the FEMA freeboard criteria. Since the width of the flood protection is determined by the desired height of the flood protection, the narrower base requirement for both the metal panel and concrete wall technologies is an important factor. A benefit of the height of the flood protection meeting the FEMA design criteria is that this estimated height varies between one-half and one and a half feet below the 1993 flood WSE of 764.5 (based on HDR 1999 report), and therefore could provide increased protection. Fabric membrane, water-inflated tubes, and water-inflated baffled bladders all require more labor and time for installation when compared to the concrete floodwall or metal panel systems. These systems also cannot meet the height requirements through the entire alignment due to the required base width for installation. 4.2.3 Flood Protection Technology Cost Flood protection technology cost estimates obtained from vendors were used to perform a cost comparison of the technologies on a cost per linear foot basis. This is shown graphically in Figure 4-3. The green line representing the baffled bladder indicates the maximum flood protection height of 6 feet specific to this technology. The purple line representing the fabric dam represents the maximum flood protection height of 10 feet specific to this technology. 4-3 Section 4 Flood Protection Plan & Cost Estimate for Downtown Parkville.docx E 3rd Street E 2nd Street E 1st Str e e t Mill Stree t Ma i n S t r e e t Ea s t S t r e e t Engl i s h L a n d i n g D r i v e UV9756 754 756 754 756 Whi t e A l o e B r a n c h Source: Esri, DigitalGlobe, GeoEye, i-cubed, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community .Section 1 Section 2 Section 3 Section 4 Section 5 Section 6 Road Crossing 1 Road Crossing 2 Road Crossing 3 Waterway 0 100 20050 Feet Figure 4-2 Flood Protection Sections Section 4 • Flood Protection Plan and Cost Estimate for Downtown Parkville The blue box on Figure 4-3 highlights the approximate flood protection heights from Table 4-1 along with their corresponding costs per linear foot. Of note, four of the technologies are within $200 per linear foot when installed at the flood protection height of 8 feet. It is important to note that the unit cost for the temporary technologies only include material costs and do not include the costs associated with installation, maintenance, and storage. Table 4-2 uses interpolated unit costs from Figure 4-3 in conjunction with the heights and lengths listed on Table 4-1 to estimate a total material cost for the installation of a single flood protection technology on the preferred alignment. The water-inflated baffled bladder flood protection technology is not included in Table 4-2 due to its installation height not meeting the requirements for the Downtown study area. Table 4-2 Flood Protection Technology Cost Comparison Description Concrete Floodwall with Footer 2 Fabric Dam1 Water- Inflated Tubes1 Metal Panels with Footer 1,3 Subtotal $1,091,100 $1,065,900 $1,059,700 $1,463,300 Gate/Road Crossings n/a 4 $147,700 $140,900 $196,700 Single Technology Total $1,091,100 $1,213,600 $1,200,600 $1,660,000 1 Technology costs were determined using cost estimates (as of September 2012) based on sole source use of flood protection technology based on a linear foot calculation. 2 Concrete floodwall unit cost for estimate provided by USACE. 3 Metal panels includes the cost of a typically footer construction. Foundation and footer costs may vary significantly depending on geotechnical analysis. 4 Concrete floodwall technology does not include cost for gate/road crossing. Any temporary flood protection technology can be utilized at these locations. Figure 4-3 Flood Protection Material Cost Curve 4-5 Section 4 Flood Protection Plan & Cost Estimate for Downtown Parkville.docx Section 4 • Flood Protection Plan and Cost Estimate for Downtown Parkville For comparison purposes, it is important to note that only the concrete wall unit cost includes installation, as this is a one-time expense. Both the concrete wall and the metal panel unit costs include an estimate of a typical footer cost, installed, as required for installation. All other technologies are represented by material cost only, as installation cost will be required for each flood event in use. Additionally, there are costs associated with the temporary flood control technologies that are not in Table 4-2 costs. These include storage, annual training costs, material replacement cost, and flood event installation costs (set-up and breakdown). 4.3 Recommended Flood Protection for Downtown Parkville A blend of flood protection technologies is recommended based on the City’s preferred flood protection alignment for the Downtown study area and the review parameters of maintenance, installation and cost. Use of permanent concrete walls and metal panels (with sill plate) road crossings is recommended as shown on Figure 4-4. An estimated conceptual cost for this recommendation is shown in Table 4-3. Please note that this cost could vary significantly based on geotechnical investigations and decisions on final aesthetics of proposed concrete wall. Table 4-3 Downtown Recommended Flood Protection Technology Conceptual Costs Description Estimated Cost Permanent Flood Protection (Concrete Floodwall) $1,091,000 Gate/Road Crossings (Metal Panels w/footer) $197,000 Subtotal $1,288,000 Easement and Acquisition (5% of Construction Cost) $65,000 Utility Coordination/Relocation (16% of Construction Cost) 1 $206,000 Local/State/Federal Permitting (5% of Construction Cost) $65,000 Engineering Design, Borings, Surveys (25% of Construction Cost) 1 $321,000 Contingency (35% of Construction Cost) 1 $460,000 Subtotal $1,117,000 Total $2,405,000 1 Percent per USACE 4-6 Section 4 Flood Protection Plan & Cost Estimate for Downtown Parkville.docx E 3rd Street E 2nd Street E 1st Str e e t Mill Stree t Ma i n S t r e e t Ea s t S t r e e t Engl i s h L a n d i n g D r i v e UV9756 754 756 754 756 Whi t e A l o e B r a n c h .Metal Panels on Sill Foundation Permanent Concrete Wall Waterway 0 100 20050 Feet Figure 4-4 Recommended Flood Protection Technology Placement (c) 2010 Microsoft Corporation and its data suppliers Section 4 • Flood Protection Plan and Cost Estimate for Downtown Parkville With this recommendation, the City could achieve protection of the Downtown area for the preliminary base flood elevation, while retaining its connection with the Missouri River and providing services to its residents. This recommendation has several benefits:  Maintenance. Maintenance requirements for the concrete wall would be limited to annual inspections and items identified during these inspections. Metal panels can be stacked and stored at existing City facilities.  Installation. With one-time installation for the concrete wall, there would be a decreased need for both City staff time and volunteer time for flood fighting activities in the Downtown study area. Installation would only be required during a flood event for the metal panels at the road crossings. While this will affect vehicular traffic in the area, Downtown would still be accessible from the north. In addition, this installation meets the width constraints present on the alignment.  Cost. The cost incurred with construction of the recommended system would primarily be a one-time construction cost. Annual inspection and maintenance costs would also be required.  Regulatory. Precedence has been set in FEMA Region VII for use of concrete walls and metal panels in updating the FIS. The City could pursue a LOMR to remove the protected areas from the SFHA zone.  Aesthetics. A permanent concrete floodwall can incorporate with current Downtown historical features, as shown on Figure 4-5 (view heading west along Highway 9) and Figure 4-6 (view south on Main Street). Figure 4-5 View of Simulated Concrete Floodwall, Facing West along Highway 9 4-8 Section 4 Flood Protection Plan & Cost Estimate for Downtown Parkville.docx Section 4 • Flood Protection Plan and Cost Estimate for Downtown Parkville Figure 4-6 View of Simulated Concrete Floodwall, Facing South along Main Street The following assumptions were made as part of this recommendation:  All recommendations are conceptual in nature. Prior to construction, recommendations should go through a formal design process and be sealed and signed by a registered professional engineer in the State of Missouri.  All cost estimates are conceptual in nature. Prior to construction, design drawings should undergo a detailed cost review based on final design.  Coordination and permits with the USACE and FEMA may be required due to the preferred flood protection alignment and construction location along the White Aloe Branch.  Coordination with BNSF is required due to the preferred flood protection alignment and construction location in the proximity of the railroad tracks.  Attainment of right-of-way and/or easements may be required along portions of the preferred protection alignment.  Utility locates were not performed or surveyed as part of this study. Sanitary and storm sewer-line crossing were identified via City provided shapefiles; however, the actual location of lines was not verified.  Stormwater drainage on the dry side of the proposed flood protection alignment was not evaluated as part of this study. 4-9 Section 4 Flood Protection Plan & Cost Estimate for Downtown Parkville.docx Section 4 • Flood Protection Plan and Cost Estimate for Downtown Parkville  Geotechnical investigation is necessary to adequately design the proposed concrete floodwall. Information obtained during a geotechnical investigation impacts the structural design of the wall, including depth, width, and reinforcing requirements.  A topographic survey of flood protection alignment area was not performed as part of this study.  The effect of flood protection on the WSE of the Missouri River was not evaluated as part of this study. The effect of flood protection on White Aloe Branch was evaluated using HEC-RAS. Utilizing the preliminary modeling information from FEMA for White Aloe Branch, no significant rise in WSE on White Aloe Branch occurs with the building of flood protection of this alignment. A memorandum with details of this analysis is included in Appendix B. 4-10 Section 4 Flood Protection Plan & Cost Estimate for Downtown Parkville.docx