HYDROLOGIC & HYDRAULIC ANALYSIS FOR THE SOUTHEAST REGIONAL PARK ENCOMPASSING ALL OR PORTIONS OF SECTIONS 10, 11, 14, 15, 22 AND 23 TOWNSHIP 16 SOUTH, RANGE 15 EAST, GRBM PIMA COUNTY, ARIZONA (All referenced elevations, unless otherwise noted, are based on NAVD 88) Prepared for: Pima County Regional Flood Control District 97 East Congress, Third Floor Tucson, Arizona 85701 By: JE Fuller Hydrology & Geomorphology Inc. 40 E. Helen Street Tucson, Arizona 85705 520-623-3112 April 2012 HYDROLOGIC & HYDRAULIC ANALYSIS FOR THE SOUTHEAST REGIONAL PARK TABLE OF CONTENTS I. INTRODUCTION ...............................................................................................................1 1.1 1.2 1.3 II. Project Location and Description.............................................................................1 Purpose and Objective .............................................................................................1 Previous Drainage Studies .......................................................................................1 HYDROLOGIC & HYDRAULIC MODELING ................................................................3 2.1 Existing Conditions Analysis...................................................................................3 III. SUMMARY OF RESULTS ................................................................................................5 IV. REFERENCES ....................................................................................................................6 LIST OF APPENDICES Appendix A FLO-2D Files LIST OF FIGURES Figure 1 Vicinity Map ............................................................................................................7 Figure 2 Location Map ...........................................................................................................8 Figure 3 Preliminary Concept Plan ........................................................................................9 Figure 4 SERP – Upstream FLO-2D Model Boundary .......................................................10 Figure 5 FLO-2D Depths (Existing Conditions) ..................................................................11 Figure 6 Revised Concept Plans for SERP ..........................................................................13 Figure 7 FLO-2D Depths (SERP Concept Plan, Fairgrounds Option #1) ...........................15 Figure 8 FLO-2D Depths (SERP Concept Plan, Fairgrounds Option #2) ...........................17 LIST OF TABLES Table 1.1 SERP – Existing Use by Parcel ...............................................................................2 Table 2.1 FLO-2D Parameters for the Upstream Contributing Wastershed ............................3 i JE Fuller/Hydrology & Geomorphology, Inc. HYDROLOGIC & HYDRAULIC ANALYSIS FOR THE SOUTHEAST REGIONAL PARK I. Page 1 INTRODUCTION This report was prepared by JE Fuller / Hydrology & Geomorphology, Inc. (JEF) under contract with the Pima County Regional Flood Control District (RFCD). It documents the extent and magnitude of flooding impacting the Southeast Regional Park under existing conditions. 1.1 Project Location and Description The Southeast Regional Park (SERP) is located west of Houghton Road just south of the I-10 interchange. It occupies approximately 2,972 acres or 4.64 square miles and collectively includes all or portions of Sections 10, 11, 14, 15, 22, and 23, of Township 16 South, Range 15 East, Gila River Base Meridian, Pima County, AZ (see Figure 1and 2). The Pima County Department of Economic Development & Tourism and the Pima County Natural Resources, Parks and Recreation Department are the primary stakeholders. Additional stakeholders include the Southwestern Fair Commission and the MC Motorsports Park. In 2010, a preliminary concept for the park was prepared (see Figure 3). This concept plan identifies both existing and proposed amenities, some of which have been approved by Pima County and are currently under construction. Portions of the concept plan are currently being updated. In 2011, a Master Plan was prepared for the Pima County Fairgrounds (Reference 1), which is managed and operated by the Southwestern Fair Commission Inc., a non-profit corporation established by Pima County. The Pima County Fairgrounds property, which occupies Section 14 in its entirety, contains several entertainment venues including the Pima County Fair, the Southwestern International Raceway, the Tucson Raceway, the Tucson Kart Club track, and the Southern Arizona Modelers RC Flying Club. The park site consists of the following 11 parcels; 305-01-0070, 305-01-009A, 305-01-0120, 305-01-013A, 305-01-014F, 305-01-004D and 305-01-4J through 4N. Table 1.1 summarizes the existing and proposed amenities associated with each parcel. 1.2 Purpose and Objective This floodplain study was prepared to identify the extent and magnitude of flooding within the boundary of the park under existing conditions. The results of the analysis and the associated hydrologic/hydraulic model will serve as the base condition model for all future developments to aid in the planning and design process. The RFCD, as a secondary stakeholder, contracted this modeling effort to ensure that a comprehensive hydrologic and hydraulic assessment of existing conditions was prepared using consistent modeling techniques and assumptions. 1.3 Previous Drainage Studies The only drainage study that was available for review was the study prepared by AMEC for the Shooting Range (Reference 2). The expansion plans for the shooting range were approved by Pima County and improvements are currently under construction. JE Fuller/Hydrology & Geomorphology, Inc. HYDROLOGIC & HYDRAULIC ANALYSIS FOR THE SOUTHEAST REGIONAL PARK Page 2 Table 1.1 – SERP- Existing Use by Parcel Parcel No. 305-01-0070 305-01-0009A Park Amenities Existing SE Regional Shooting Range -- Proposed SE Regional Shooting Range Expansion, Archery Range Under Construction X SE Regional Skeet Range X 305-01-0120 MC Motorsports Park (formerly Pima Motorsports Park), including the Musselman Honda Circuit MC Motorsports Park expansion 305-01-013A -- F-4 Road Course, Off-Road Track, Future Uses 305-01-014F -- F-4 Road Course, Sports Fields, Future Uses 305-01-004D, 305-01-4J thru 4N Pima County Fairgrounds, including SW International Raceway, Tucson Raceway Park, Tucson Kart Club, and So. Arizona Modelers RC Flying Club Pima County Fairgrounds expansions and upgrades, including Option #1 and #2 . JE Fuller/Hydrology & Geomorphology, Inc. HYDROLOGIC & HYDRAULIC ANALYSIS FOR THE SOUTHEAST REGIONAL PARK II. HYDROLOGIC & HYDRAULIC MODELING 2.1 Existing Conditions Analysis Page 3 The existing conditions analysis was conducted using FLO-2D, Version 2009.06 (Reference 3). The FLO-2D software package was used to evaluate both rainfall and runoff within the boundary of the study area (i.e., the contributing watershed area) and the project area (i.e., SERP). FLO2D was selected to model the study area, since the lack of definition within the contributing watershed does not lend to the use of traditional lumped-parameter methods such as HEC-1 or HEC-HMS, and the FLO-2D model offers a greater level of detail in modeling distributary channels within a watershed. FLO-2D allowed detailed modeling of the entire study area, which encompasses approximately 46.5 square miles and distribution of the resulting flood hydrographs over the entire upstream boundary of the project area. The digital elevation model (DEM) data used in the FLO-2D modeling was 2008 Pima Association of Governments (PAG) data. The initial FLO-2D model, which covered the entire 46.5 square mile contributing drainage area, was a 100-foot-grid model that included 129,606 nodes. The hydrologic modeling was done using the SCS runoff methodology option in FLO-2D. The total FLO-2D modeling area is shown on Figure 4. Table 2.1 summarizes the data and parameters used to develop the100-foot grid model, which is also referred to as the upstream contributing watershed model. Table 2.1 - FLO-2D Parameters for the Upstream Contributing Watershed Parameter/Data Description Topographic Data FLO-2D Grid Rainfall Data Soils Data SCS Curve Number Roughness Coefficient PAG 2008 DEM data. Data processing included elevation resampling to reduce data density. 100-foot grid developed from PAG 2008 DEM data using FLO-2D GDS program. Data adjusted where needed to eliminate ponding grids. NOAA Atlas 14 Upper 90% confidence interval rainfall data for 3-hour storm was used. Rainfall data determined from NOAA raster grids. The RAIN.DAT file contains the maximum individual rainfall depth for the entire model followed by a 3-hour distribution table followed by a table of reduction values to adjust maximum rainfall to rainfall for grid locations within watershed. A SCS Type II, 3-hour storm distribution (as described in Pima County Tech Policy 018) was utilized for rainfall input. NRCS soils data from U.S. General Soil Map (STATSGO). The SCS option available within FLO-2D was utilized to convert rainfall to runoff. SCS curve numbers were determined using shape files containing information on (1) hydrologic soil group (HSG) from the Pima County GIS soilshyd.shp file, which contains soils information from NRCS Soil Survey #AZ669, (2) vegetative cover type (from Arizona Game & Fish data), and (3) impervious cover from county land use data. The resulting CN values ranged from approximately 70 to 98, depending on HSG, cover and percent impervious. A roughness coefficient of 0.035 was used with adjustment in isolated locations to aid in model stability. JE Fuller/Hydrology & Geomorphology, Inc. HYDROLOGIC & HYDRAULIC ANALYSIS FOR THE SOUTHEAST REGIONAL PARK Page 4 Although the 100-foot grid model shows flood prone areas within the boundary of the entire study area, a more-detailed project area model utilizing a 30-foot-grid spacing was prepared for planning and development purposes. The 30-foot grid model used output hydrographs from the 100-foot model that were generated along the upstream boundary of the project area. This higher resolution model is also referred to as the project site model. The project site FLO-2D model included 162,836 nodes within the boundary of the roughly five square mile project site. Onsite runoff within the boundary of the project site was also modeled using the SCS runoff methodology option in FLO-2D. The modeling parameters for the project site model are consistent with the previously described parameters for the upstream FLO-2D model. In addition, the following elements were included in the project site model.   A 6 barrel 36" CMP culvert under the Southwestern International Raceway drag strip (south of the Fairgrounds entrance) was modeled using the hydraulic structures option of FLO-2D; however, a single-barrel 36" CMP under the drag strip (north of the Fairgrounds entrance) was not modeled. A concrete crash or barrier wall along the upstream side of the drag strip was modeled using the levee option of FLO-2D. JE Fuller/Hydrology & Geomorphology, Inc. HYDROLOGIC & HYDRAULIC ANALYSIS FOR THE SOUTHEAST REGIONAL PARK III. Page 5 SUMMARY OF RESULTS Using the results of the existing-condition FLO-2D analysis, two exhibits were prepared to illustrate the potential impact the 100-year flood will have on the project site, as shown on the 2011 aerial photograph. The first exhibit (Figure 5, Sheet 1 of 2) shows the areas of inundation where the depth is greater than 0.2 feet. The second exhibit (Figure 5, Sheet 2 of 2) shows the area of inundation where the depth is greater than 1.0 feet. Both exhibits also show the 100-year discharge at several locations within the park boundary. The first existing-condition floodplain exhibit clearly shows that the majority of the site is subject to shallow sheet flooding during the 100-year event. However, the second exhibit shows that existing improvements will not be subjected to major flooding (i.e., flooding depths greater than 1.0 feet) during the 100-year event. The high flood hazard areas are for the most part limited to the undeveloped portions of the project site. For this reason, a master drainage or mitigation plan is not warranted. Using the existing-condition FLO-2D model as the basis for planning and design, future improvements can accommodate existing runoff and minimize their impact on the existing flood plain. Using the concept plan information shown on Figure 3 in conjunction with updated information obtained from individual stakeholders, two revised concept plans were prepared to illustrate the impact that the 100-year flood event will have on the Southeast Regional Park as currently envisioned. One of the revised plans incorporates Master Plan Option 1 for the Pima County Fairgrounds, as presented in Reference 1, and one incorporates Option 2. Figure 6, Sheet 1 of 2 shows Option 1 and Figure 6, Sheet 2 of 2 shows Option 2. To avoid clutter, the corresponding floodplain overlays only show the outline or footprint of the proposed improvements. Figure 7 shows Option 1 under shallow-sheet flow conditions (Sheet 1 of 2) and where the depths of flow are greater than one foot (Sheet 2 of 2). Figure 8 shows Option 2 under the same two flow conditions (Sheets 1 of 2 and 2 of 2, respectively). The FLO-2D files are provided in Appendix A or are available upon request to those who only have a PDF copy of this report. JE Fuller/Hydrology & Geomorphology, Inc. HYDROLOGIC & HYDRAULIC ANALYSIS FOR THE SOUTHEAST REGIONAL PARK Page 6 IV. REFERENCES 1. POPULOUS, Pima County Fairgrounds, Master Plan, Southwestern Fair Commission, Inc., October 27, 2011. 2. AMEC, Final Drainage Report, Southeast Regional Park Shooting Range, Phase II, January, 2011. 3. FLO-2D Software, Inc., FLO-2D Reference Manual, Version 2009 and FLO-2D Data Input Manual, Version 2009.06, October, 2009. JE Fuller/Hydrology & Geomorphology, Inc. IN CO M TE M ER CI AL RS ZO TA TE 10 NE SHOOTING RANGE SPORTING CLAYS COMMERCIAL ZONE MODEL AIRPLANES FAIRGROUNDS ARCHERY RANGE HORSE RACING MOTOCROSS PARK COMMERCIAL ZONE KART TRACK DRAGSTRIP NASCAR Figure 3 F-4 ROAD COURSE Preliminary Concept Plan PIMA COUNTY ENTERTAINMENT DISTRICT INCLUDING FAIRGROUNDS SPORTS FIELDS S RITA RD EO LD VAI L S CAMINO LOMA ALTA Exhibit 4 1 - SERP Upstream FLO-2D Model Boundary Figure RD E M LD SPA NI S HT R AR TS W PI S D TO L HI AN EL I10 LL V LE E C V RD N KE AN OC Y ER EO S Y S HARRISON RD W I10 FR O NT AG E AVE R I1 0 RD AL C W D E BREKKE RD E CO LOSS E DAWN RD E BE NS O N HY S WENTWORTH RD E I1 0 FR O NT AG E RD E E WETSTONES RD N CALLE RINCONADO N WENTWORTH RD S HOUGHTON RD E ANDRADA RD OM EN EW Y Y S HARRISON RD AH OI T SM ELP W CAMINO DEL TORO E CAMINO AURELIA ¯ 1 inch = 3,000 feet Legend SERP_Project_Boundary FLO-2D Model Boundary ON SS E SAHUARITA RD W SAHUARITA RD R MA SH R ON I T STA D Figure 5 Sheet 1 of 2 SERP FLO2D Depths, 3-hr Storm, 30-ft Grid Model (100-year Flood Plain, Depths greater than 0.2 feet) Legend ¯ FPXSECS with Q100 Flow Depth-30'-3hr-with Culv&Wall Var 0.0 - 0.2 1 inch = 500 feet 0.2 - 0.5 253 0.5 - 1.0 1.0 - 2.0 76 2.0 - 3.0 >3 717 HARRISON SERP_Proj_Bdry 30 0 2 929 1099 1333 42 0 8 12 88 2 1292 BREKKE 1260 2086 1962 1701 2480 4 81 625 4 55 23 3 484 917 HOUGHTON 773 20 9 510 DAWN Figure 5 Sheet 2 of 2 SERP FLO2D Depths, 3-hr Storm, 30-ft Grid Model (100-year Flood Plain, Depths greater than 1.0 feet) Legend ¯ FPXSECS with Q100 Flow Depth-30'-3hr-with Culv&Wall Var 0.0 - 0.2 1 inch = 500 feet 0.2 - 0.5 253 0.5 - 1.0 1.0 - 2.0 76 2.0 - 3.0 >3 717 HARRISON SERP_Proj_Bdry 30 0 2 929 1099 1333 42 0 8 12 88 2 1292 BREKKE 1260 2086 1962 1701 2480 4 81 625 4 55 23 3 484 917 HOUGHTON 773 20 9 510 DAWN Figure 7 SERP FLO2D Depths, 3-hr Storm, 30-ft Grid Model (Pima County Fairgrounds Option #1, Sheet 1 of 2) Legend ¯ FPXSECS with Q100 Flow Depth-30'-3hr-with Culv&Wall Var 0.0 - 0.2 1 inch = 500 feet 0.2 - 0.5 253 0.5 - 1.0 1.0 - 2.0 76 2.0 - 3.0 >3 717 HARRISON SERP_Proj_Bdry 30 0 2 929 1099 1333 42 0 8 12 88 2 1292 BREKKE 1260 2086 1962 1701 2480 4 81 625 4 55 23 3 484 917 HOUGHTON 773 20 9 510 DAWN Figure 7 SERP FLO2D Depths, 3-hr Storm, 30-ft Grid Model 2 of 2) (Pima County Fairgrounds Option #1, Sheet 1 Legend ¯ FPXSECS with Q100 Flow Depth-30'-3hr-with Culv&Wall Var 0.0 - 0.2 1 inch = 500 feet 0.2 - 0.5 253 0.5 - 1.0 1.0 - 2.0 76 2.0 - 3.0 >3 717 HARRISON SERP_Proj_Bdry 30 0 2 929 1099 1333 42 0 8 12 88 2 1292 BREKKE 1260 2086 1962 1701 2480 4 81 625 4 55 23 3 484 917 HOUGHTON 773 20 9 510 DAWN Figure 8 SERP FLO2D Depths, 3-hr Storm, 30-ft Grid Model (Pima County Fairgrounds Option #2, Sheet 1 2 of 2) Legend ¯ FPXSECS with Q100 Flow Depth-30'-3hr-with Culv&Wall Var 0.0 - 0.2 1 inch = 500 feet 0.2 - 0.5 253 0.5 - 1.0 1.0 - 2.0 76 2.0 - 3.0 >3 717 HARRISON SERP_Proj_Bdry 30 0 2 929 1099 1333 42 0 8 12 88 2 1292 BREKKE 1260 2086 1962 1701 2480 4 81 625 4 55 23 3 484 917 HOUGHTON 773 20 9 510 DAWN Figure 8 SERP FLO2D Depths, 3-hr Storm, 30-ft Grid Model (Pima County Fairgrounds Option #2, Sheet 2 of 2) Legend ¯ FPXSECS with Q100 Flow Depth-30'-3hr-with Culv&Wall Var 0.0 - 0.2 1 inch = 500 feet 0.2 - 0.5 253 0.5 - 1.0 1.0 - 2.0 76 2.0 - 3.0 >3 717 HARRISON SERP_Proj_Bdry 30 0 2 929 1099 1333 42 0 8 12 88 2 1292 BREKKE 1260 2086 1962 1701 2480 4 81 625 4 55 23 3 484 917 HOUGHTON 773 20 9 510 DAWN Appendix A FLO-2D Files JE Fuller/Hydrology & Geomorphology, Inc.