SR 826/PALMETTO EXPRESSWAY PROJECT DEVELOPMENT & ENVIRONMENT STUDY FROM SR 93/I 75 TO GOLDEN GLADES INTERCHANGE Preliminary Drainage Report

Transcription

1 SR826 Project Development and Environment Study Preliminary Drainage Report SR 826/PALMETTO EXPRESSWAY PROJECT DEVELOPMENT & ENVIRONMENT STUDY FROM SR 93/I 75 TO GOLDEN GLADES INTERCHANGE Preliminary Drainage Report Financial Project ID: FAP No.: P / ETDM No.: Miami Dade County Prepared For: FDOT District Six 1000 NW 111 th Avenue Miami, Florida Prepared by: Ribbeck Engineering, Incorporated SW 120 th Street, Suite Miami, Florida September 12, 2014 FM #: / FAP #: P / ETDM #: 11241

2 SR 826 Project Development and Environment Study Preliminary Drainage Report EXECUTIVE SUMMARY This project is located in Miami-Dade County along SR 826 from the I-75 Interchange to the Golden Glades Interchange. The existing facility will be widened to accommodate four additional travel lanes. As a result of this widening the existing conveyance systems will need to be upgraded to the current stormwater management requirements as specified by the permitting agencies. The widening works will affect all the interchanges located within the project limit, and will also impact the stormwater collection system. The proposed configuration will also impact the existing detention swales that are currently providing water quality treatment, and stormwater runoff attenuation. The challenge for this project is to satisfy the water quality requirements, and also not to increase the storm runoff beyond the original pre-development discharges. The design team in anticipation to the development of suitable drainage alternatives has met with the Miami-Dade Department of Regulatory and Economic Resources (DRER), and the South Florida Water Management Agency (SFWMD). Possible drainage alternatives were presented, and reviewed at a meeting with DRER on June 6 th, Another meeting was held with SFWMD on December 20 th, These two meetings defined two main drainage design alternatives as possible feasible solutions to satisfy the agencies requirements. This conceptual drainage report evaluates two drainage design alternatives considering the use of exfiltration trenches or French drains, and the use of a wet detention pond. Drainage design alternative 1 will maximize the use of French drain within the project limit. Drainage design alternative 2 will drain the project by using a combination of French drains, and a detention pond. The drainage alternatives were thoroughly investigated for hydraulic suitability, contamination potential, environmental impacts, right-of-way acquisition costs, and construction costs. Drainage design alternative 1 while having the possibility of satisfying the agencies water quality requirement falls very short of satisfying the pre-development discharge limit. Drainage design alternative 2 satisfies the water quality and quantity requirements by providing compensatory treatment in a detention pond located north of the Opa-Locka airport on land that belongs to the airport. A meeting was held on October 9 th, 2012 with the Miami-Dade Aviation Department about the possibility of transferring the title to the pond parcel to the FDOT, thus offsetting the right-of-way cost. This proposal was well received. As a result of these meetings, and the possibility of performing a land title transfer, the recommended drainage alternative is alternative 2. This report provides the justifications for the preferred alternative. FM #: / FAP #: P / ETDM #: Page 2 of 664

3 SR 826 Project Development and Environment Study Preliminary Drainage Report TABLE OF CONTENTS 1.0 INTRODUCTION PROJECT DESCRIPTION STORMWATER REQUIREMENTS Water Quality Criteria SFWMD Water Quality Criteria DRER Water Quality Criteria Water Quantity Criteria SFWMD Water Quantity Criteria DRER Water Quantity Criteria FDOT Water Quantity Criteria Ground Water Elevation HYDRAULIC DESIGN REQUIREMENTS Conveyance Systems Storm Sewer Systems Spread Criteria Exfiltration Trenches Design Criteria for Wet and Dry Ponds Pond Design Criteria by SFWMD Pond Design Criteria by DRER Pond Design Criteria by FDOT PRE DEVELOPMENT BASINS Pre Development Basin Pre Development Basin Pre Development Basin Pre Development Basin Pre Development Basin Pre Development Basin Pre Development Basin POST DEVELOPMENT BASINS Post Development Basin Post Development Basin Post Development Basin Post Development Basin Drainage Alternative Post development Basin 5, drainage alternative Post development Basin 6, drainage alternative Post development Basin Drainage Alternative Post development Basin 5, 6, drainage Alternative C 8 CANAL PROPOSED CULVERTS PERMITTING REQUIREMENTS South Florida Water Management District (SFWMD) Miami Dade County Department of Regulatory and Economic Resources (DRER) Miami Dade County Building and Zoning Department Florida Department of Transportation FM #: / FAP #: P / ETDM #: Page 3 of 664

4 SR 826 Project Development and Environment Study Preliminary Drainage Report TABLE OF CONTENTS (CONTINUED) 8.5 Florida Department of Environmental Protection (FDEP) FDEP General Construction NPDES Permit United Army Corp of Engineers (USACE) Florida Fish and Wildlife Conservation Commission RECOMMENDATION, CONCLUSION LIST OF APPENDICES: Appendix A: Appendix B: Appendix C: Appendix D: Appendix E: Appendix F: Appendix G: Appendix H: Appendix I: Appendix J: Appendix K: Appendix L: Project Correspondence DERM C 8 Basin Stormwater Master Plan Geotechnical Data Pre Development Conditions Drainage Backup Calculations Pre Development Conditions Alternative 1 ICPR Nodal Link Schematic Pre Development Conditions Alternative 1 ICPR Input Pre Development Conditions Alternative 1 ICPR Output Post Development Conditions Drainage Backup Calculations Post Development Conditions Alternative 1 ICPR Nodal Link Schematic Post Development Conditions Alternative 1 ICPR Input Post Development Conditions Alternative 1 ICPR Output Pre Development Conditions Alternative 2 ICPR Input Appendix M: Pre Development Conditions Alternative 2 ICPR Output Appendix N: Appendix O: Appendix P: Post Development Conditions Alternative 2 ICPR Nodal Link Schematic Post Development Conditions Alternative 2 ICPR Input Post Development Conditions Alternative 2 ICPR Output FM #: / FAP #: P / ETDM #: Page 4 of 664

5 SR 826 Project Development and Environment Study Preliminary Drainage Report LIST OF TABLES: LIST OF FIGURES: Table 1: FEMA FIRM Community Panel Numbers Figure 1: Project Study Area Location Map Table 2: DRER Water Quantity Criteria Figure 2: Project Study Area USGS Map Table 3: Project Land Use Figure 3: Project Study Area Land Use Map Table 4: DERM October Average Groundwater Level Figure 4: Project Study Area Soils Map Table 5: Tailwater Boundary Conditions Figure 5: Project Study Area Soils Map Legends Table 6: Design Rainfall Depth Figure 6: Average October Ground Water Levels Table 7: Project Average Percolation Rates Figure 7: Water Control Map Table 8: Water Quality Control Analysis Summary Alternative 1 Figure 8: Recommended Alternative Typical Section Table 9: Water Quality Control Analysis Summary Alternative 2 Table 10: Water Quantity Control Analysis Summary Alternatives 1 & 2 Figure 9: FIRM MAP No.: 12086C0112L Panel 112 of 1031 Figure 10: FIRM MAP No.: 12086C0114L Panel 114 of 1031 (Part 1) Table 11: Flood Protection Analysis Summary Pre Development Conditions Figure 11: FIRM MAP No.: 12086C0114L Panel 114 of 1031 (Part 2) Table 12: Flood Protection Analysis Summary Post Development Conditions Alternative 1 Table 13: Flood Protection Analysis Summary Post Development Conditions Alternative 2 Figure 12: FIRM MAP No.: 12086C0116L Panel 116 of 1031 (Part 1) Figure 13: FIRM MAP No.: 12086C0116L Panel 116 of 1031 (Part 2) Table 14: Drainage Design Alternatives Estimated Construction Cost Figure 14: FIRM MAP No.: 12086C0117L Panel 117 of 1031 (Part 1) Figure 15: FIRM MAP No.: 12086C0117L Panel 117 of 1031 (Part 2) Figure 16: FIRM MAP No.: 12086C0136L Panel 136 of 1031 (Part 1) FM #: / FAP #: P / ETDM #: Page 5 of 664

6 SR 826 Project Development and Environment Study Preliminary Drainage Report LIST OF EXHIBITS: Description Sheet No. Project Drainage Overview 1 Drainage Alternative 1 Network Overview 2 Drainage Alternative 2 Network Overview 3 Pre Development Drainage Map 4 to 22 Post Development Drainage Map Alternative 1 23 to 41 Post Development Drainage Map Alternative 2 42 to 52 Pre Development Node Link Schematic 1 to 4 Post Development Alternative 1 Node Link Schematic 1 to 13 Post Development Alternative 2 Node Link Schematic 1 to 4 FM #: / FAP #: P / ETDM #: Page 6 of 664

7 SR 826 Project Development and Environment Study Preliminary Drainage Report 1.0 INTRODUCTION The Florida department of Transportation District 6 (FDOT) is conducting a Project Development and Environmental (PD&E) study for the eventual widening and interchange improvements for the State Road (SR) 826/Palmetto Expressway from the I-75 to the Golden Glades Interchange. The primary purpose of this PD&E Preliminary Drainage Report is to identify and quantify the conveyance systems from the project, and focus on the contributory basin characteristics, and design considerations. This project will construct additional traffic lanes, improve the existing interchanges, and upgrade the drainage systems to the latest standard by the regulatory agencies. This report will describe and evaluate the drainage system for both the pre-development and the post-development condition. This project is situated in Section 7, 8, 9, 10, 15, 16, 17 and 18 of Township 52 South, and Range 41 East, and in Section 13, 14 and 23 of Township 52 South and Range 40 East. The project is situated in its entirety within the Miami Dade County. The regulatory water management districts are the South Florida Water Management District (SFWMD), and the Miami-Dade Department of Regulatory and Economic Resources (DRER). 2.0 PROJECT DESCRIPTION The project starts at the I-75 Interchange and ends at the Golden Glades Interchange. Of the different Alternatives considered to improve the functionality of SR 826, alternative 2 was found to be the most appropriate. This alternative will widen SR 826 from right of way line to right of way line. From NW 154 th Street to NW 27 th Avenue SR 826 will be widened from 6 lanes to 10 lanes, while from NW 27 th Avenue to the Golden Glades Interchange SR 826 will be widened from 8 lanes to 10 lanes. The final lane configuration will accommodate 2 inside travel lanes in each direction that will function as limited access express lanes. The proposed widening will affect the existing drainage collection systems. The drainage systems will need to be completely reconstructed since the widening work will cause a change in the existing profiles more specifically in areas of super-elevation transition, and overpasses or interchanges. The following interchanges are encountered: NW 154 th Street NW 67 th Avenue NW 57 th Avenue NW 47 th Avenue NW 37 th Avenue NW 27 th Avenue NW 17 th Avenue NW 12 th Avenue The existing drainage system varies from start of project to end of project and consists of stage controlled detention ponds at the I-75 Interchange, and dry swales and gravity pipes for the remaining project length. This project is located within various water management district drainage basins. The basins identified are the C-8, and the C-9 East from SFWMD. The project outfall points that are encountered are as follow: I-75 wet and dry ponds discharging into the C-8 Canal Grahams Dairy Canal (tributary of C-8) NW 154 th Street Interchange ponds discharging into Peters Pike Canal (tributary of C-8) NW 67 th Avenue outfall that discharges north into Golden Glades Canal (tributary of C-9) NW 57 th Avenue outfall that discharges south into Red Road Canal (tributary of C-8) NW 42 nd Avenue outfall that discharges north toward Carol City Canal (tributary of C-9) NW 17 th Avenue outfall that discharges south into Spur 2 Canal (tributary of the C-8) The project is located in the North West area of Miami-Dade County, east of the Everglades protection area. The surrounding area is very flat and varies slightly in height from elevation 5.00 feet to 7.00 feet NGVD for adjacent areas west of NW 57 th Avenue, and from 7.00 feet to 9.00 feet for adjacent areas east of NW 57 th Avenue. The groundwater table at project location varies from 2.00 feet to 3.00 feet NGVD. According to the FIRM maps the project is located in zone X, and zone AE with a base flood level that varies from 6.00 feet to 7.00 feet NGVD. Encroachment to the 100 year vase flood is limited to the portion of SR 826 from NW 54 th Street to NW 61 st Place, from NW 20 th Avenue to NW 18 th Avenue, and from NW 17 th Avenue to NW 14 th Avenue. The surrounding area is highly urbanized north and south of the corridor with virtually no vacant available parcels. The project straddles the Town of Miami Lakes, the City of Miami Gardens, and a section of unincorporated Miami-Dade County. The project is bisected by two tributaries of the SFWMD. They are the C-8 and the C-9 East basins. A list of the FIRM Community Panel numbers that cover the project is shown in Table 1. Note: Conversion between vertical datums used in this report is approximately NGVD29 NAVD88 = (approx.) FM #: / FAP #: P / ETDM #: Page 7 of 664

8 SR 826 Project Development and Environment Study Preliminary Drainage Report 3. Retention systems only need to provide 50% of the wet detention volume. Community Panel No. Miami Dade County Effective Date 12086C0112L September 11, C0114L September 11, C0116L September 11, C0117L September 11, C0136L September 11, 2009 Table 1 FEMA FIRM Community Panel Numbers 3.0 STORMWATER REQUIREMENTS This project must satisfy state guidelines for water quality, and quantity. 3.1 Water Quality Criteria This project is considered as a remediation work to a deficient drainage system and will not consider water quality as the limiting design criteria. The following water quality criteria are being described below for information purpose only SFWMD Water Quality Criteria According to the SFWMD Permit Information Manual Volume IV, all projects must meet the following volumetric retention/detention requirements: 1. For wet detention systems, the first inch of runoff from the project or the total runoff from 2.5 inches times the percent of imperviousness, whichever is greater, must be detained on site. A wet detention system is a system that maintains the control elevation at the seasonal high groundwater elevation and does not bleed down more than one half inch of detention volume in 24 hours. 2. Dry detention systems only need to provide 75% of the required wet detention volume. Dry detention systems must maintain the control elevation at or above one foot above the seasonal high groundwater elevation. 4. For projects with more than 50% of imperviousness, discharge to the receiving water bodies must be made through baffles, skimmers, or other mechanisms suitable from preventing oil and grease from discharging to or from the retention/detention areas DRER Water Quality Criteria The first inch of runoff volume from the most hydrologic remote point on the drainage basin is required to be retained onsite. The methodology for estimating this volume is outlined in the Design of Drainage Structures An Update Policy for the Design of Storm Runoff Drainage Structures. For highway systems, DRER requires that the first inch of runoff must be retained for a rainfall event with a 10 year frequency, and infiltrated into the groundwater in a period of 24 hour or less. The use of dry ponds is preferred to avoid the contact of storm runoff with the Biscayne surface aquifer. Alternatively the use of wet ponds is allowed provided that there exists an impermeable layer such as clay or much that will prevent the pond water from migrating to the Biscayne surface aquifer. 3.2 Water Quantity Criteria The SFWMD and DRER have jurisdiction over the stormwater quantity criteria for this project SFWMD Water Quantity Criteria For projects that overflow into surface waters, the SFWMD requires that the peak postdevelopment discharge rate shall not exceed the pre-development discharge rates for the SFWMD 25-Year 72-Hour rainfall. The district also requires that the street centerline be set at or above the 5-Year 24-Hour rainfall. The rainfall depth for each individual storm is obtained from the hyetographs listed in their design criteria manual (page C-1 to page C-11) DRER Water Quantity Criteria Protection from flooding has long been the primary objective of Miami-Dade County. The sizing of a drainage system is determined by the design storm and the land use type. The design storm is based on the County Intensity Duration Frequency (IDF) curves as shown in W.C. 1.1 and W.C The table below summarizes this agency s requirements. In addition DRER states that a safety factor of 4, exfiltration trenches with 24 inches perforated pipes 100 feet long, and 18 inches pipes shall be used for section line and half section line roadways, and exfiltration trenches with 36 inches perforated pipes on arterial roads. FM #: / FAP #: P / ETDM #: Page 8 of 664

9 SR 826 Project Development and Environment Study Preliminary Drainage Report DESIGN STORM FREQUENCIES AND FLOOD LIMITS Type of Area Rainfall Frequency Flood Limit Residential and Commercial Areas 2-Lane roads in Residential and Commercial Areas 4-Lane roads in high density, high traffic areas Private parking lots and similar paved areas 5 year To crown of street, or to within 15 of a dwelling or other occupied building, whichever is lower 5 year, except 10 year for a bridge or culvert in the canal system To crown of street 10 year To outer edge of traffic lanes 5 year As per Florida Building Code Table 2 - DRER Water Quantity Criteria FDOT Water Quantity Criteria Per FDOT chapter F.A.C. the drainage system must meet the offsite discharge criteria which includes analysis of the critical storm events with the 2 to 100 year frequency of 1 hour to 10 days duration. FDOT district 6 has identified the following six storm events as the critical storm events and requires the analysis of 10-year 1-hour, 10-year 8-hour, 10-year 24-hour, 100-year 1- hour, 100-year 8-hour, and 100-year 24-hour storm events only. The rainfall intensity and depths for these storm events that apply for this project is listed in Zone 10 of the FDOT Drainage Manual. 3.3 Ground Water Elevation Ground water elevations vary for the 25-Year 72-Hour, 100-Year 24-Hour, and the 10-Year 24- Hour. For the 100-Year 1-Hour, and the 10-Year 1-Hour, the water table is constant. The seasonal high water elevation is locally referred to as the October Ground Water Elevation and is depicted in the Miami-Dade County Standard W.C In the project vicinity the October ground water level varies from 2.50 NGVD on the east to 3.50 NGVD on the west. 4.0 HYDRAULIC DESIGN REQUIREMENTS This section outlines the general design requirements and guidelines needed to satisfy current FDOT, SFWMD, and DRER standards. 4.1 Conveyance Systems Conveyance systems collect and carry stormwater runoff to receiving bodies of water, ponds, pump stations, exfiltration trenches, and drainage wells. The two main conveyance systems used in roadway projects are storm sewer systems and roadway and median ditches. The design of both storm sewer systems and conveyance ditches shall be based on FDOT drainage design criteria. These criteria are summarized as follows: Storm Sewer Systems Storm sewer pipes need to be designed for a 10 year storm, and for sag vertical curves which have no outlet other than the storm sewer, a 50 year storm shall be used. The 50 year design storm applies also for storm sewer system being drained by a pump station. The pipes shall be sized and laid on a slope that will maintain minimum and maximum full flow velocities of 2.5 feet and 15 feet per second Spread Criteria The minimum longitudinal gutter grade shall be kept at 0.3% to properly drain the pavement and reduce the width of the spread, or the likelihood of hydroplaning. The careful spacing of the inlets is required to limit the spread resulting from a constant 4.0 inches per hour storm. The spread criteria are summarized as follows. Typical Section Condition Design Speed (mph) Spread Criteria* Parking Lane or Full Width Shoulders All No encroachment All Other Design speed 45 Keep ½ of lane clear 45 < Design Speed 55 Keep 8 of lane clear Design Speed > 55 No encroachment In addition to the above standards the distance to the terminal inlet must be no greater than 250 feet, and the bypass flow shall exceed 25% of the initial flow for the intermediate inlets. FM #: / FAP #: P / ETDM #: Page 9 of 664

10 SR 826 Project Development and Environment Study Preliminary Drainage Report 4.2 Exfiltration Trenches Exfiltration trenches are allowed when in-situ soil hydraulic conductivity is sufficient to promote exfiltration of the required stormwater quality volumes. This type of drainage system must be designed in accordance with the following design criteria and parameters. Exfiltrate to the groundwater the greater of the SFWMD or DRER water quality volume. As per the FDOT Design Standard Index 285, the minimum trench width shall be 4.5 feet, and the minimum pipe diameter of 24 with the invert set at or above the Average October Water Elevation W.C Provide baffles, skimmers, and sumps to minimize entrance of oils and sediments into drainage pipes. Bottom elevation of baffles shall be set 18 inches below the pipe invert. Depth of trench must be at or below the percolation test hole depth to a maximum of 15 feet. Limit the allowable discharge to 0.1 cfs per linear foot of trench. 4.3 Design Criteria for Wet and Dry Ponds Pond Design Criteria by SFWMD The design of water bodies such as dry or wet detention/retention ponds must follow criteria and guidelines from the Environmental Resource Permit Information Manual Volume IV - Basis of Review for Environmental Resource Permit Applications within the South Florida Water Management District, Chapter 5.0, Provide a length to width ratio of 3:1 to maximize pollutants removal and trap sediments. 2. Provide a dry pond bottom area, or a permanent wet pool area based on a storage depth of 3 feet. This depth will satisfy the bleed down time of 24 hours for the water quality volume. 3. Provide for dry pond a minimum vertical separation of 12 inches to 18 inches between the water table and the pond bottom. This separation will prevent the condition of a wet pond bottom. 4. Provide for wet pond a minimum depth of 10 feet to 15 feet below the permanent wet pool. This depth will prevent the growth of aquatic vegetations. Minimum pond width shall be 100 feet. 5. Provide a maintenance berm width of 15 feet around the pond (20 feet preferred). In some cases the corners should be rounded to facilitate access. The maintenance berm should be compacted, and sloped inward at 1:8. 6. Provide a berm slope of 1:4 or flatter. 7. Provide a littoral shelf sloped at 1:10 for a distance of 10 feet for the case of wet pond. 8. Structures discharging directly into a pond should have a 4 feet sump for trapping of sediments. 9. The minimum bleeder diameter should be 3 inches, or a V notch with a central angle of 20 degrees and the invert set at the permanent wet pool water surface. 10. For overflow pipe going thru the berm, provide one or multiple seepage collar. 11. No utilities shall be located within a pond. 12. Local ordinance must be consulted in reference to the minimum setback from property line, well field, and drain field. 13. Woody vegetation must not be planted on the embankment or allowed to grow within 15 feet of the toe of the embankment and 25 feet from the principal spillway structure. 14. For wet pond the minimum bottom area shall not be less than 0.50 acre, and the average width not less than 100 feet. 15. The shallow littoral area shall equal 20% of the wet pond area or 2.5% of the total drainage basin area whichever is greater. 16. The sediment sump area shall be deeper than 12 feet and the area equals 25% to 50% of the total pond area Pond Design Criteria by DRER Miami Dade County is located within the Biscayne Aquifer which is the primary source of fresh water. This aquifer is unconfined, and because of its high conductivity this department has discouraged the use of wet pond in the county. In the event that a wet pond is needed to satisfy some design requirements, the following criteria must be followed. 1. Dry ponds are allowed anywhere in the county provided that the water quality and quantity storage volume are provided. 2. A dry pretreatment volume must be provided upstream of a wet pond prior for the runoff to be discharged into the pond. This dry pretreatment volume is based on a 5 year storm frequency and duration equals to the time of concentration Tc plus the time it takes to generate 1 inch of runoff T1. FM #: / FAP #: P / ETDM #: Page 10 of 664

11 SR 826 Project Development and Environment Study Preliminary Drainage Report 3. In cases where the setting of a dry pretreatment volume storage area is not feasible, then the pond bottom should be lined with an impervious material such as the use of muck or clay materials 18 inches in thickness. 4. Where a wet pond is located near an airport, the depth of the littoral zone and depth of pond shall be increased to the 15 feet depth range to discourage the establishment of wetland vegetations that could attract water fowls. The bleeder invert shall be set above the permanent wet pool surface at an elevation equals to the dry pretreatment volume Pond Design Criteria by FDOT The Florida Department of Transportation has drafted a set of guidelines for the design and construction of detention and retention ponds. These guidelines are described in detail in the State of Florida Department of Transportation Drainage Manual, Section These guidelines are described below. 1. Ponds shall be designed to provide a minimum of 20 feet of horizontal clearance between the top edge of the normal pool elevation and the right of way line. At least 15 feet adjacent to the pond shall be at a slope of 1:8 or flatter. The berm area shall be covered with sod. 2. The pond corners shall be rounded to provide an acceptable turning radius for maintenance equipment. 3. To compensate for grading irregularities, 1 foot of freeboard is required above the maximum design stage. 4. Ponds having side slopes steeper than 1:4 shall be provided a protective barrier to prevent unauthorized entry. Gates shall be placed at appropriate locations. 5. When ponds are not accessible directly from the road right-of-way, an access easement shall be provided. 6. Establish pond setback relative to highway clear zone. Typically a 60 feet setback is needed as per exhibit 4-A from the Plans Preparation Manual, Volume PRE DEVELOPMENT BASINS The project area has been subdivided into seven (7) basins based on a pre-development/existing set of maps that have been prepared using available survey information and other available archived drainage maps. The SR 826 corridor went through many improvements over the year, and the original pipe layout has been modified to accommodate the changes. However, all the subsequent changes did not significantly impact the basins boundaries and outfall points. The description of the pre-development basins will start from the south west toward the east. Refer to project overview drainage maps. 5.1 Pre Development Basin 1 This basin starts at SR 924 within the I-75 Interchange and ends at NW 154 th Street Interchange. The drainage system installed consists of continuous exfiltration trenches, pipes, and inlets that discharge into stage controlled wet and dry ponds. Within the I-75 Interchange the southbound mainline and ramps drain to a dry pond which overflows into the Peter s Pike Canal, while the northbound mainline and ramps drain to a wet pond that overflows into Grahams Dairy Canal. North of the culvert that links the C-8 Canal with Grahams Dairy Canal, SR 826 is drained by exfiltration trenches, and collecting solid pipes that discharge the run-off into the dry ponds of NW 154 th Street Interchange. These ponds are stage controlled and discharge into the C-8 Canal (Peter s Pike Canal). The total drainage area is acres. 5.2 Pre Development Basin 2 Basin 2 begins at the 154 th Street overpass (approx. station ) and extends to the big bend near project station ending at the bridge at the C-8 Canal, from Right-of-Way to Right-of-Way. This North-South basin consists of interconnected drainage pipes and includes bridge scuppers collection pipes. The collected runoff overflows into longitudinal dry swales located on either side of the expressway. The east swale also collects runoff from NW 77 th Avenue, and NW 167 th Avenue. These swales discharge into the C-8 Canal. The total drainage area is estimated at acres. 5.3 Pre Development Basin 3 Basin 3 starts at the big bend just after the C-8 crossing and ends at NW 67 th Avenue. The collection system consists of inlets and pipes that discharge to interconnected longitudinal swales. The interconnection between the two swales is by a 48 cross drain located at project station The south longitudinal swale also collects runoff from NW 167 th Street. These swales flow by gravity toward a storm sewer collection system located along NW 67 th Avenue that overflows via a 36 pipe to the C-9 Canal (Golden Gates Canal). Over the years this drainage basin was modified by the addition of 24 exfiltration trenches along the eastbound exit ramp. The total drainage area is estimated at acres. FM #: / FAP #: P / ETDM #: Page 11 of 664

12 SR 826 Project Development and Environment Study Preliminary Drainage Report 5.4 Pre Development Basin 4 Just east of basin 3 lies basin 4. It is bound to the west by NW 67 th Avenue Interchange and to the east by NW 57 th Avenue Interchange. The drainage system consists of inlets, and gravity pipes that discharge into longitudinal interconnected parallel swales that also receive runoff from the south and north frontage roads of NW 167 th Street. The swales are interconnected by a 48 cross drain located at project station The south swale from project station to station has been modified to include several exfiltration trenches. This basin drains in two different directions: it drains to the west to the collection system placed along NW 67 th Avenue that drains to the C-9 Canal via a 36 pipe, and it drains to the groundwater via the French Drains in the south swale. The total drainage area is estimated at acres. 5.5 Pre Development Basin 5 This basin starts just west of the NW 57 th Avenue Interchange and ends at the NW 47 th Avenue Interchange. The collection system includes inlets, and gravity pipes that discharge into longitudinal interconnected parallel swales. The interconnection point is by a 24 cross drain located at station The swales also receive runoff from the south and north frontage roads of NW 167 th Street. This basin drains to the west at the collection system of NW 57 th Avenue via an 8 x5 concrete box culvert that links the north and south section of the Red Road Canal. The north exit ramp at the NW 57 th Avenue Interchange was widened, and as a result 127 feet of exfiltration trench were installed. The exfiltration trench installed is self contained and has no overflow. The total drainage area is estimated at acres. 5.6 Pre Development Basin 6 This basin starts at NW 47 th Avenue Interchange and ends at the NW 27 nd Avenue overpass. Basin 6 is bisected by the interchange of NW 37 th Avenue, and the overpasses of NW 42 nd Avenue, and NW 32 nd Avenue. Basin 6 from NW 47 th Avenue to NW 42 nd Avenue drains from west to east and from NW 42 nd Avenue to NW 27 th Avenue from east to west via interconnected longitudinal conveyance swales. The south and north swale are interconnected by a 24 cross drain located at station The north exit ramp at the NW 47 th Avenue Interchange was widened, and as a result 586 feet of exfiltration trench was installed. The exfiltration trench installed is self contained and has no overflow. Similarly to the previous basins the south and north frontage roads of NW 167 th Street drains to the swales. The overflow point for basin 6 is at NW 42 nd Avenue via a 36 outfall pipe that discharges to the Carol City Canal. From the NW 42 nd Avenue overpass to the NW 37 th Avenue Interchange, basin 6 includes both the south and north frontage roads of NW 167 th Street. The drainage system installed is similar to the previously described sub-drainage basins. It consists of inlets and gravity pipes discharging into interconnected conveyance swales located south and north of the expressway. From the NW 37 th Avenue Interchange to the NW 32 nd Avenue overpass, basin 6 includes the south and north frontage roads of NW 167 th Street. This basin is drained by inlets and gravity pipes discharging into parallel non-connected conveyance swales. Over the year close to 950 feet of exfiltration trenches were added to the north swale. The north swale is landlocked and has no overflow. The south swale overflows into a gravity system at NW 37 th Avenue that connects to the previous sub-basin. From the NW 32 nd Avenue overpass to just short of the NW 27 th Avenue Interchange, basin 6 includes the south and north frontage roads of NW 167 th Street. The drainage system consists of inlets and gravity pipes that discharge into interconnected parallel conveyance swales that are located south and north of the expressway. The interconnection point is via a 24 cross drain located at station These conveyance swales overflow into the gravity system of the NW 32 nd Avenue overpass that connects to the previous sub-basin which overflows at the NW 42 nd Avenue outfall via a 36 pipe. The total drainage area for basin 6 is estimated at acres. 5.7 Pre Development Basin 7 The limit of basin 7 is from NW 27 th Avenue to the Golden Gate Interchange. It is bisected by the NW 22 nd Avenue overpass, and the interchanges of NW 17 th Avenue, and 12 th Avenue. It includes the south and north frontage roads of NW 167 th Street. The drainage system consists of inlets, and gravity pipes that discharge into interconnected parallel conveyances swales. The conveyance swales are connected at station via an elliptical 53 x34 cross drain. The swales receive runoff from the frontage roads as well. The north swale flows east toward an elliptical 53 x34 storm sewer that connects to the sub-basin bound by NW 22 nd Avenue and NW 17 th Avenue. The drainage system between the NW 22 nd Avenue overpass to the NW 17 th Avenue Interchange includes the south and north frontage roads of NW 167 th Street and consists of inlets, gravity pipes, and interconnected conveyance swales located on either side of the expressway. The swales are connected at station The north swale receives runoff from the previous subbasin via an elliptical 53 x34 storm sewer system that continues east toward the Spur 2 Canal at NW 17 th Avenue. The overflow from basin 6 is via a 36 pipe that connects to a 10 x10 concrete box culvert. From the NW 17 th Avenue Interchange to the NW 12 th Avenue Interchange, basin 7 includes the south and north frontage roads of NW 167 th Street. This basin flows from east to west toward the FM #: / FAP #: P / ETDM #: Page 12 of 664

13 SR 826 Project Development and Environment Study Preliminary Drainage Report culvert crossing at NW 17 th Avenue. The drainage system consists of inlets, gravity pipes, and interconnected swales. The north swale is drained by ditch bottom inlets, and a gravity pipe network that receives runoff from the expressway, and the south swale. The overflow of the north swale is via a 30 pipe that connects to a 10 x10 concrete box culvert. This sub-basin starts at the NW 12 th Avenue Interchange and ends at the entrance ramps of the Golden Glades Interchange. The drainage system is similar to the described systems of the previous sub-basins. At roughly where NW 167 th Street north frontage road ends, the south swale connects to the north swale via a cross drain. The north swale collects runoff from the expressway and the south swale, and is drained by ditch bottom inlets linked by gravity pipe that drain west toward the sub-basin of NW 17 th -NW 12 th Avenue via underground gravity pipes. The connection to this sub-basin is via a 24 pipe. The sub-basin from NW 12 th Avenue to Golden Glades Interchange is not part of this project. The total drainage area for basin 7 is estimated at acres. 6.0 POST DEVELOPMENT BASINS The preferred build alternative selected will construct 16 travel lanes (two frontage road lanes each way, five lanes each way and two express lanes each way) impacting the entire right of way by construction. The existing drainage systems will need to be reconstructed. The post development drainage basins could be subdivided into two different areas. From the I-75 Interchange to the NW 67 th Avenue Interchange the post-development drainage system will be a modification of the pre-development drainage system. From the NW 67 th Avenue Interchange to the NW 17 th Interchange a total of two drainage alternatives will be evaluated to replace the non compliant direct discharge gravity system. These alternatives are described below, and depicted in the project overview drainage maps. Drainage alternative 1: this alternative will evaluate the use of exfiltration trenches to drain the project. The exfiltration trench systems in the post-development layout will use the same outfalls as in the pre-development layout. Drainage alternative 2: this alternative will evaluate the use of a gravity storm sewer collection system draining into a stage controlled offsite wet pond that overflows into the C- 8 Canal. The tributary area for this alternative will start at NW 57 th Avenue, and end at NW 27 th Avenue. 6.1 Post Development Basin 1 The post-development basin 1 will have the same limit as the pre-development but with slightly different boundary. The total drainage area for this basin is estimated at acres. North of the SR 924 Interchange SR 826 will be widened both to the east and the west to accommodate two median express lanes and a southbound connector ramp from SR 826 and NW 154 th Street to westbound SR 924. The construction of these ramps to the west will encroach on the Peters Pike Canal. Another improvement will be a direct connector ramp from westbound SR 924 to northbound SR 826. The new connectivity provided by these ramps will affect the east wet detention pond, the west dry detention pond located within the SR 924/SR 826 Interchange. The remaining collection system north of SR 924 to the NW 154 th Street Interchange will be impacted by the widening of SR 826. The new collection system will be divided into two sub-basins Sub-basin1-1 starts at the SR 826/SR 924 Interchange and ends at the NW 154 th Street Interchange. The collection system will consist of exfiltration trenches, inlets and gravity pipes that will drain south toward the east wet detention pond that discharges to the Grahams Dairy Canal, and the west dry detention pond that discharges to the C-8 Canal. The existing control structures for these two ponds will be adjusted to provide the required water quality volume, and limit the post-development to the pre-development discharge. Sub-basin 1-2 starts at the NW 154 th Street Interchange and ends at the culvert that links the C-8 Canal with Graham s dairy Canal. The collection system will consist of exfiltration trenches, inlets and gravity pipes that will drain to the infield dry ponds of the NW 154 th Street Interchange. The control structures will be modified to accommodate the increase in impervious areas and satisfy the water quality volume requirement, and the pre/post discharge requirement. Post development basin 1 will be drained by 7,600 feet of exfiltration trenches. The required exfiltration trenches length is 6,289 feet. 6.2 Post Development Basin 2 Post-development basin 2 starts at the NW 154 th Street Interchange and ends at the C-8 Canal crossing. This basin is bordered to the east by the Miami Garden golf course and to the east by the C-8 Canal. The western most limit is a on NW 154 th Street (at the extent of the roadway restoration) where a 36 exfiltration trench drains via overflow weir #5 into Basin 1. The tributary area includes NW 77 th Avenue frontage road. The proposed drainage system will be drained by a continuous exfiltration trench of 36 French drain pipe that will discharge to the C-8 Canal. To accommodate the widening and the inclusion of the southbound/westbound ramp that connects SR 826 with SR 924, the Peter s Pike Canal will be shifted toward the west. The minimum canal width of 50 will be maintained where feasible, and double barrels 20 x10 will be installed at the encroachment area. The average ground elevation is around +6.75, while the October groundwater level is around NGVD (about NAVD). Within this drainage basin a total of two percolation tests were performed (P-4, P-5), and the average percolation rate is 1.01x10-4 FM #: / FAP #: P / ETDM #: Page 13 of 664

14 SR 826 Project Development and Environment Study Preliminary Drainage Report cfs/ft 2 /ft of head. This percolation rate is considered to be average. The controlling design factor for this basin is the depth to the water table. The total drainage area is acres, of which acres are impervious, and 1.68 acres are pervious. The exfiltration trench proposed will be 5 feet wide and will have a 36 diameter perforated pipe. The overflow points will be to the C-8 Canal. The controlling weir elevation will be set at (NAVD) or top of trench. One control structure will be provided. The required length of exfiltration trenches per water quality standard is 3,341 feet. The maximum length provided is 1,690 feet as per site constraint. Refer to project overview drainage maps. 6.3 Post Development Basin 3 Post-development basin 3 starts at the C-8 Canal crossing and ends at the NW 67 th Avenue Interchange. The total drainage area is estimated at acres, of which acres are impervious and 8.41 acres are pervious. The drainage area includes the east frontage road of NW 77 th Avenue, and the south frontage road of NW 167 th Street. The expressway will be widened to full extent of the available right-of-way. The drainage system will consist of inlets and pipes discharging into a dry detention swale located on the north side and west side of SR 826. This swale will be located on the available right of way of the west extension of the north frontage road of NW 167 th Street. From NW 67 th Avenue to the C-8 Canal that extension was never constructed but the available land is still zoned as right of way. This dry detention swale has a bottom area of 5 acres which will be set at (NAVD) or 1 foot (or greater) above the October ground water elevation of about NGVD (about NAVD). Within this drainage basin a total of four percolation tests were performed (P-6, P-7, P-8, P-9), and the average percolation rate is 1.13x10-4 cfs/ft 2 /ft of head. The dry detention swale is stage controlled at elevation before overflowing to the south into an exfiltration trench that outfall to the C-8 Canal. The controlling elevation for the exfiltration trenches will be set at The exfiltration trench proposed will be 5 feet wide and will have a 36 diameter perforated pipe. One control structure will be provided. The required length of exfiltration trenches per water quality standard is 6,712 feet. The maximum length provided is 6,120 feet as per site constraint. The required water quality will be provided by the combined detention volume in the dry swale and the exfiltrated volume in the trenches. 6.4 Post Development Basin 4 The limit of post-development basin 4 is the same as in the pre-development. This basin starts at the NW 67 th Avenue Interchange and ends at the NW 57 th Avenue Interchange. The drainage area includes the south and north frontage road of NW 167 th Street. The average ground elevation is around +5.60, while the October groundwater level is around NGVD (Approx. about NAVD). Within this drainage basin a total of three percolation tests were performed (P-10, P-11, P-12), and the average percolation rate is 1.06x10-4 cfs/ft 2 /ft of head. This percolation rate is considered to be average. The controlling design factor for this basin is the depth to the water table. The total drainage area is acres, of which acres are impervious, and 2.84 acres are pervious. The exfiltration trench proposed will be 5 feet wide and will have a 36 diameter perforated pipe. The overflow points will be to the collection system placed along NW 67 th Avenue that drains to the C-9 Canal via a 36 pipe, and also to the collection system of NW 57 th Avenue via an 8 x5 concrete box culvert that links the north and south section of the Red Road Canal. The controlling weir elevation will be set at (NAVD) or top of trench. A total of two control structures will be provided at NW 67 th Avenue. The required length of exfiltration trenches per water quality standard is 11,920 feet. The maximum length provided is 9,250 feet which will consist of two parallel exfiltration trenches located on either side of NW 167 th Street south frontage road, and north frontage road. This total includes length reduction of 400 feet from contaminated sites as further described below. On the north frontage road near the intersection at NW 67 th Avenue, there is a contamination site at the Citgo gas station. As a result 300 feet of potential exfiltration trench will need to be replaced with solid pipe as per DRER. There is another contamination site at the Esserman Nissan car dealership near the south frontage road intersection with NW 57 th Avenue. Similarly as before 400 feet of potential exfiltration trenches were replaced with solid pipe. More length of exfiltration trenches could be reduced to solid pipes until a contamination extent survey is performed. However, the 400 feet reduction proposed at each contamination sites per the DRER database is conservative and could be adjusted. 6.5 Drainage Alternative Post development Basin 5, drainage alternative 1 The limit of post-development basin 5 is the same as in the pre-development. This basin starts at the NW 57 th Avenue Interchange and ends at the NW 47 th Avenue Interchange. The drainage area includes the south and north frontage road of NW 167 th Street. The average ground elevation is around +6.25, while the October groundwater level is around NGVD (about NAVD). Within this drainage basin a total of three percolation tests were performed (P-13, P-14, P-15), and the average percolation rate is 9.03x10-5 cfs/ft 2 /ft of head. This percolation rate is considered to be poor. The total drainage area is acres, of which acres are impervious, and 3.46 acres are pervious. The exfiltration trench proposed will be 5 feet wide and will have a 36 diameter perforated pipe. The overflow points will be to the collection system of NW 57 th Avenue via an 8 x5 concrete box culvert that links the north and south section of the Red Road Canal. The FM #: / FAP #: P / ETDM #: Page 14 of 664

15 SR 826 Project Development and Environment Study Preliminary Drainage Report controlling weir elevation will be set at (NAVD) or top of trench. A total of two control structures will be provided at NW 57 th Avenue. The required length of exfiltration trenches per water quality standard is 8,921 feet. The maximum length provided is 9,600 feet which will consist of two parallel exfiltration trenches located on either side of NW 167 th Street south frontage road, and north frontage road. This total includes length reduction from contaminated sites further described below. On the north frontage road near the intersection at NW 57 th Avenue, there is a contamination site at the Amoco gas station. As a result 400 feet of potential exfiltration trench will need to be replaced with solid pipe as per DRER. There is another contamination site at the Mobile gas station on the north frontage road near NW 47 th Avenue. Similarly as before 400 feet of potential exfiltration trenches were replaced with solid pipe. Refer to project overview drainage maps Post development Basin 6, drainage alternative 1 The limit of post-development basin 6 starts at the NW 47 th Avenue Interchange and ends at the NW 27 th Avenue Interchange. The drainage area includes the south and north frontage road of NW 167 th Street. The average ground elevation is around +6.50, while the October groundwater level is around +3.00NGVD (about NAVD). Within this drainage basin a total of seven percolation tests were performed (P-16, P-17, P-18, P-19, P-20, P-21, P-22), and the average percolation rate is 9.01x10-5 cfs/ft 2 /ft of head. This percolation rates are considered to be poor. The total drainage area is acres, of which acres are impervious, and 9.64 acres are pervious. This drainage basin is bisected into an east and west basin by the NW 42 nd Avenue pipe outfall. The exfiltration trench proposed will be 5 feet wide and will have a 36 diameter perforated pipe. The overflows points will be to the collection system of NW 42 nd Avenue via a 36 pipe that discharges to the Carol City Canal. The controlling weir elevation will be set at (NAVD) or top of trench. A total of two (2) control structures will be provided on either side of the outfall pipe of NW 42 nd Avenue. The required length of exfiltration trenches per water quality standard is 16,895 feet. The maximum length provided is 17,050 feet which will consist of two parallel exfiltration trenches located on either side of NW 167 th Street south frontage road, and north frontage road. This total includes length reduction from contaminated sites further described below. On the north frontage road near the intersection at NW 47 th Avenue, there is a contamination site approximately at the Mobile & Shell gas station location. On the south frontage road near the intersection at NW 42 nd Avenue, there is a contamination site at the CITGO gas station. On the north frontage road near the intersection at NW 37 th Avenue, there is a contamination site at the Chevron gas station. As a result of these contaminations sites the potential length of exfiltration trench will need to be replaced with solid pipe as per DRER. There is another contamination site near NW 43 rd Avenue at the Lad & Lassie cleaners, and at the Valero gas station on the north frontage road near NW 42 nd Avenue. Similarly as before the length of exfiltration trenches were replaced with solid pipe. The provided length of 17,050 feet reflects these reductions. 6.6 Post Development Basin 7 The limit of post-development basin 7 is the same as in the pre-development. This basin starts at the NW 27 th Avenue Interchange and ends at the NW 17 th Avenue Interchange. The drainage area includes the south and north frontage road of NW 167 th Street. The average ground elevation is around +4.50, while the October groundwater level is around NGVD (about NAVD). Within this drainage basin a total of four percolation tests were performed (P-23, P- 24, P-25, P-26), and the average percolation rate is 1.68x10-4 cfs/ft 2 /ft of head. This percolation rate is considered to be average. The total drainage area is acres, of which acres are impervious, and 2.78 acres are pervious. There is a superfund contaminated site that prohibits the use of wet ponds or exfiltration trenches within a 1 mile radius of that site. The drainage sub-basin from NW 22 nd Avenue to NW 17 th Avenue lies entirely inside the exclusion radius. The overflow points will be to the Spur 2 Canal via two control structures with weir set at elevation The required length of exfiltration trenches per water quality standard is 6230 feet. The provided length is 4,400 feet. 6.7 Drainage Alternative Post development Basin 5, 6, drainage Alternative 2 One alternative to the exfiltration trench will be the used of wet ponds. A meeting was held at DRER and various alternatives of this pond option were discussed. The stretch of SR 826 from the NW 67 th Avenue Interchange to the NW 17 th Avenue Interchange could be drained by the use of two gravity ponds. From the NW 67 th Avenue Interchange to the NW 27 th Avenue Interchange a drainage system consisting of inlets and tertiary gravity pipes will drain to a secondary system of large diameter pipes that will drain toward a main collector pipe placed along NW 47 th Avenue. The secondary pipes are divided into two laterals placed along NW 167 th Street south, and north frontage road. The sizes of these laterals vary from 54 to 72. Along NW 47 th Avenue, and NW 42 nd Avenue, the east and west laterals flow into elliptical pipes of 121 x77 gravity mains that conveys the runoff south toward a stage control wet pond of acres which will be referred as Pond A. The total tributary area from NW 57 th Avenue to NW 27 th Avenue is acres, of which acres are impervious, and acres are pervious. FM #: / FAP #: P / ETDM #: Page 15 of 664

16 SR 826 Project Development and Environment Study Preliminary Drainage Report Pond A is located just north of the Opa-Locka airport, north of the C-8 Canal, on airport property that is currently not used. This pond will straddle portion of a large tract of land grouped under Miami-Dade county folio number , and Pond A has ample storage to satisfy the water quality and quantity. The control structures will consist of two (2) weir drop structures. The broad crest weirs will be set at elevation to provide a detention volume of Ac-ft which exceeds the required Ac-ft.. Refer to project overview drainage maps. 7.0 C 8 CANAL PROPOSED CULVERTS The project will encroach on the C-8 Canal right of way at two locations. The first location starts at station and ends at station It is located just north of the I-75 Interchange, and south of the NW 154 th Street Interchange. A double barrel culvert 20 x10 will be laid within this limit. The overall length is 2,222 feet. At around station , a junction box will need to be constructed to link the 20 x10 double barrel culvert with an existing 72 culvert that links the Peter Pike Canal with the Graham s Dairy Canal. The second canal encroachment occurs at the southbound exit ramp that leads to NW 154 th Street, and I-75. A double barrel culvert 20 x10 of 481 feet in length will be installed. The endwalls will be located at station , and at station The SFWMD in the Permit Information Manual Volume V states that the allowable head loss through a proposed culvert shall be limited to one-tenth of a foot or less. Furthermore the crown of the culvert must allow the district s floating equipment to pass. The culvert must be set in such a manner to allow the passage of a boat having an 8 foot wide deck, with the deck being 2 feet above the seasonal high optimum water surface elevation of the canal, with a minimum of 2 feet of clearance from the boat to the culvert walls on either side. The invert of the culvert must be set one-half foot above the design canal bottom, and provide also a minimum water depth of 5 feet as measured from the seasonal low water elevation. 8.0 PERMITTING REQUIREMENTS This project will require multiple agencies coordination, and permit. Among the required permits the following are deemed to be critical to the project schedule. 8.1 South Florida Water Management District (SFWMD) In Miami-Dade County the SFWMD requires that all development projects that do not provide full on-site retention with greater than 40 acres of project area or over 1-acre of wetland impact must be permitted as an Individual Environmental Resources Permit (ERP). The ERP permit is a jointpermit application that addresses surface and storage of surface waters, dredge and fill, and wetland mitigation. This application is submitted to the SFWMD but is also reviewed by the Florida Department of Environmental Protection (FDEP) and U.S. Army Corps of Engineers (USACOE). Based on discussions with the SFWMD regulatory staff, they recommend that the entire SR 924 Extension be permitted under a single individual conceptual ERP application. As each phase of the corridor improvements is carried forward to final design, general construction ERP permits will be obtained. The land parcel in question for the construction of the Offsite Pond A is owned by the Miami-Dade County Aviation Department (MDCAD). It is yet to be determined what type of agreement the legal departments of FDOT and MDCAD will enter into regarding the procurement of the land parcel. For works within a SFWMD Canal the District also requires a Right-of-Way Occupancy Construction Permit. Finally, a Short Term and Long Term Dewatering Construction Permit are required by the District for projects with dewatering activities. 8.2 Miami Dade County Department of Regulatory and Economic Resources (DRER) Any stormwater management system that discharge into surface waters located within Miami- Dade County, including lakes, canals or wetlands, require a DRER Class II permit. A Class I, or Coastal Construction, permit is required for works within a tidally influenced canal. Class I permits deal with preservation and/or mitigation of natural coastal resources such as mangroves, sea grass beds and coral and sponge hard bottoms. A Class III permit is required for works in canals under Miami-Dade County Jurisdiction. Any dredge or fill activity in freshwater wetlands requires a Class IV Freshwater Wetlands Permits. A Class V permit is required for temporary dewatering projects. A Class VI permit, instead of a Class II, is required if there is contamination within the project right-of-way limits. 8.3 Miami Dade County Building and Zoning Department Lakes in Miami-Dade County have to follow Standard Lake Bank criteria and an unusual use permit has to be obtained from Miami-Dade County Zoning Department. FM #: / FAP #: P / ETDM #: Page 16 of 664

17 SR 826 Project Development and Environment Study Preliminary Drainage Report 8.4 Florida Department of Transportation Drainage systems discharging into an FDOT system require a Drainage Connection Permit. Chapter FAC outlines the criteria and requirements of an FDOT Drainage Connection permit. 8.5 Florida Department of Environmental Protection (FDEP) Stormwater management systems such as drainage wells require a Class V Drainage Well Permit from the Florida Department of Environmental Protection (FDEP) for construction and monitoring of drainage deep wells. These permits are typically obtained by the well drilling contractor. As part of this permit, the contractor must field verify that the wells casings are at the 10,000 PPM TDS line. In addition, the open hole shall be further drilled to find structurally stable and permeable limestone formation and well shall be further tested to meet well percolation design capacity. 8.6 FDEP General Construction NPDES Permit The FDEP under the Federal Clean Water Act (CWA) requires that construction projects that disturb 5-acres or more require a General Construction National Pollutant Discharge Elimination System (NPDES) Permit. Procedures for complying with the General Construction NPDES include submitting a Notice of Intent (NOI), developing and implementing a Stormwater Pollution Prevention Plan (SWPPP) and submitting a Notice of Termination (NOT). The NOI must be submitted to the USEPA at least two (2) days in advance of the start of construction and should include the following information: 1. SFWMD ERP cover page; 2. A certification that the SWPPP has been prepared in accordance with Part IV of the General Construction NPDES Permit criteria; 3. A narrative statement certifying that the SWPPP provides compliance with approved State of Florida issued permits, erosion sediment control plans, and stormwater management plans. The SWPPP must specify the mechanisms for managing stormwater, including control of soil erosion and sediment control, and inspection and maintaining the effectiveness of the specified controls. The SWPPP consists of six phases as follows: 1. Site Evaluation and Design Development; 2. Assessment; 3. Control Selection and Erosion Control Plans Design; 4. Certification and Notification; 5. Construction/Implementation; 6. Final Stabilization/Termination. The SWPPP must include erosion and sediment control Best Management Practices (BMPs). These controls will depend on site-specific characteristics and the construction schedule as follows: 1. Areas that will not be re-disturbed for a period of time must be stabilized by temporary seeding or mulching. 2. Off-site vehicle tracking of sediments and generation of dust shall be minimized. 3. Structural controls must be specified for diverting runoff flow from disturbed areas, storing flows, or limiting the discharge of pollutants from exposed areas. Examples of such control may include the following: a. earth dikes; b. silt fences; c. sediment traps; d. sediment basins; e. drainage swales; f. check dams; g. subsurface drains; h. storm drain inlet protection; i. reinforced soil; j. retaining systems; k. gabions; l. turbidity barriers. After the SWPPP is executed and the project is stabilized and terminated, a NOT is submitted to the FDEP and project records should be retained for a minimum of three (3) years FM #: / FAP #: P / ETDM #: Page 17 of 664

18 SR 826 Project Development and Environment Study Preliminary Drainage Report 8.7 United Army Corp of Engineers (USACE) A permit from USACE will also be required for the project for dredge and fill and wetland impact activities. For wetland impacts less than 0.5 acres the project is permitted as a Nationwide Permit. For wetland impact above 0.5 acres the project is permitted under an Individual Permit. recommendation is based on construction cost, hydraulic efficiency, and overall benefit to the environment (water quality). The overall benefit of alternative 2 is attenuation of the design storm, and reduction of discharges from the pre-development runoff flow. 8.8 Florida Fish and Wildlife Conservation Commission Project will require close coordination with Florida Fish and Wildlife Conservation Commission for impacts/relocation of endangered species. 9.0 RECOMMENDATION, CONCLUSION Drainage alternative 1 will provide a total of 55,710 feet of exfiltration trenches. This total is far short of the 66,715 feet of exfiltration trenches required to satisfy the water quality. The deficit of 11,005 feet will need to be installed in another drainage basin such as basin 6 where the exfiltration rate is not so poor. Within the limit of this drainage basin the installation of 11,005 feet will require the construction of four parallel lines along the north and south frontage road of NW 167 th Street. Alternative 1 will have an overall estimated cost evaluated at $31,251,474. This estimate includes the construction cost for the secondary collecting systems which includes inlets and gravity pipes. Drainage alternative 2 serves the dual purpose of providing water quality treatment and flood protection for basin 5, and basin 6, but also to provide compensatory treatment for 11,005 feet of exfiltration trenches above the required length necessary for full water quality treatment as established in Alternative 1. This pond will be located on vacant county land north of the Opa- Locka airport registered under folio number , and The proposed wet pond will be large enough to handle the FDOT critical storm runoff, the water quality volume, and also provide compensatory treatment volume for other deficient drainage basin within the project. Alternative 2 and portion of Alternative 1 that applies will have a construction cost estimate of $36,612, This estimate is based on the real estate value of the parcels. Historically the county and the FDOT have established administrative procedures to transfer lands needed for economic development projects. The transfer of these parcels fall into this category. Therefore, it is probable that the title of these parcels will be transferred from the county to the FDOT. This type of transaction will further reduce the construction cost estimate to $30,869, Similarly to the provided estimate of Alternative 1, the construction cost estimate of the secondary collection systems is included in this total. The preferred alternative is a combination of drainage alternative 1 and drainage alternative 2. For basin 1 through 4, and basin 7, alternative 1 (exfiltration trenches) is the recommended alternative. For basin 5, and basin 6, alternative 2 is the recommended alternative. This FM #: / FAP #: P / ETDM #: Page 18 of 664

19 BASIN BASIN 1 BASIN 2 SR 826/PALMETTO EXPRESSWAY FROM I 75 TO NW 17 AVENUE PD&E STUDY LIMITS I 75 TO NW 154 ST NW 154 ST TO C 8 CROSSING TABLE 4. TAILWATER BOUNDARY CONDITIONS RECEIVING WATERBODY INITIAL PETERS PIKE CANAL & GW1 PETERS PIKE CANAL & GW2 FDOT DESIGN STORM TAILWATER (ft. NAVD88) 10YR 1HR PEAK 10YR 8HR INITIAL PEAK 10YR 24HR INITIAL PEAK SFWMD DESIGN STORM TAILWATER (ft. NAVD88) 25YR 72HR INITIAL PEAK C 8 CANAL & GW C 8 CANAL & GW BASIN 3 C 8 CROSSING TO NW 67A VE GOLDEN GLADES CANAL & GW BASIN 4 NW 67 AVE TO NW 57 AVE GW SR 826/PALMETTO EXPRESSWAY FROM I 75 TO NW 17 AVENUE PD&E STUDY TABLE 3. DERM OCTOBER AVERAGE GROUNDWATER LEVEL BASIN LIMITS RECEIVING CANAL DERM OCTOBER GW LEVEL ft NGVD29 ft NAVD88 BASIN 1 I 75 TO NW 154 ST PETERS PIKE BASIN 2 NW 154 ST TO C 8 CROSSING PETERS PIKE C BASIN 3 C 8 CROSSING TO NW 67AVE C GOLDEN GLADES BASIN 4 NW 67 AVE TO NW 57 AVE CLOSED BASIN 5 NW 57 AVE TO NW 47 AVE RED RD BASIN 6 NW 47 AVE TO NW 27 AVE CAROL CITY BASIN 7 NW 27 AVE TO NW 17 AVE NW 17 AVE SPUR BASIN 5 NW 57 AVE TO NW 47 AVE RED RD CANAL& GW BASIN 6 NW 47 AVE TO NW 27 AVE CAROL CITY CANAL & GW BASIN 7 NW 27 AVE TO NW 17 AVE NW 17 AVE CANAL & GW NOTE: INITIAL S ARE CONSISTENT WITH DERM OCTOBER AVERAGE GROUNDWATER LEVEL PEAK S ARE CONSISTENT WITH DERM C 8 BASIN STORMWATER MASTER PLAN Page 19 of

20 SR 826/PALMETTO EXPRESSWAY FROM I 75 TO NW 17 AVENUE PD&E STUDY SR 826/PALMETTO EXPRESSWAY FROM I 75 TO NW 17 AVENUE PD&E STUDY TABLE 5. DESIGN RAINFALL DEPTH DESIGN STORM RAINFALL DEPTH (INCHES) FDOT 10 YR, 1 HR STORM 3.6 FDOT 10 YR, 8 HR STORM 6.8 FDOT 10 YR, 24 HR STORM 9.0 SFWMD 25 YR, 72 HR STORM 13.0 TABLE 6. PROJECT AVERAGE PERCOLATION RATES BASIN LOCATION K AVERAGE K AVERAGE cfs/ft 2 ft cfs/ft 2 ft BASIN 1 I 75 TO NW 154 ST 1.27E E 04 BASIN 2 NW 154 ST TO C 8 CROSSING 1.01E E 04 BASIN 3 C 8 CROSSING TO NW 67A VE 1.13E E 04 BASIN 4 NW 67 TO 57 AVE 1.06E E 04 BASIN 5 NW 57 TO 47 AVE 9.03E 05 NW 47 TO 42 AVE 9.30E 05 BASIN 6 NW 42 TO 37 AVE 8.66E E 05 NW 37 TO 32 AVE 9.10E 05 NW 32 TO 27 AVE 8.95E 05 BASIN 7 NW 27 TO 22 AVE 1.66E E 04 NW 22 TO 17 AVE 1.70E 04 NOTE: PERCOLATION RATES BASED ON AVG. 15' DEPTH Page 20 of 651 Page 20 of 664