1. Storm Analysis and Design Prepared for Riverton City 4/13/14 CGM Consultants

2. Problem Statement Riverton City is a rapidly growing city in Salt Lake County. Many new subdivisions are projected for development in the upcoming years. To minimize construction costs, an alternative storm water design has been requested by the city.

3. Scope The results of this project are a preliminary analysis and design for typical subdivisions in Riverton City Royal Farms is a representative subdivision found in Riverton City, and was used for the analysis in this project.

4. Royal Farms Subdivision Royal Farms Subdivision is a 29.8 acre subdivision located East of Bangerter Highway.

5. Pre-Development Runoff Time of Concentration: 10 minutes Runoff Volume: 5,500 ft 3

6. Post-Development Runoff Time of Concentration: 18 minutes Runoff Volume: 23,280 ft 3

7. Pre- and post-development runoff volumes from the 10 year storm were analyzed using Watershed Modeling Systems (WMS). According to NOAA, The 10 year storm precipitation was estimated to be 1.24 inches of rainfall. From WMS, the pre-development runoff volume was found to be about 5,500 cubic feet. The post-development runoff volume was found to be 23,280 cubic feet. The low impact design (LID) for the representative subdivision must hold the difference of these volumes, or 17,780 cubic feet. Runoff Comparison

8. Pre-Development Runoff: 23,280 ft 3 Post-Development Runoff: 5,500 ft 3 Difference: 17,780 ft 3

9. The Design AutoCAD

10. Template Used a file provided by Riverton City as our template

11. Parameters Swale design ◦Width ◦Location ◦Swale entry Roadway design ◦Traveled way ◦Dividing side treatment

12. Swale The design called for a swale with a width of 5.5 feet along the sidewalk Swales are not to intersect with driveways Meant for the roadway runoff Have inlets between driveways

13. Roadway Between property lines are 54’ 29’ of designated roadway ◦2% grade on the normal crown and sidewalks 12.5’ of side treatment on each side ◦Includes:  Sidewalk 6ft  Swales 5.5 ft  Curbs 1ft

14. CAD Drawings

15. Ideal Lot Typical driveway of 30ft width ◦70% of properties have 30ft width, vs 16ft Sidewalk adjacent to and leading to the house

16. Close up of Swale Dimensions are in feet 5.5000 6.0000

17. Swale

18. Development Swales added to every roadside

19. Before and After

21. Cost Benefit Analysis

22. Simulated Development Agreement Storm Drain and Irrigation Cost Savings of 17% Non-Conservative

23. Limitations and Assumptions Arbitrary Runoff Coefficient ◦Pre- versus Post- Land Use Criteria 1.8% Grade Sloping Eastward Rational Method Verified ◦Approximated Using NRCS Curve Method Hydraulic Radius ◦0.375 ft for 18” pipe Cost-Benefit Analysis Errors

24. Evaluating Product Quality & Deliverables Property/Easement Issues HOA Regulations Public Nuisance Sand Filters

25. CGM Consultants 4.3.1 Graduate Student Advisor Adam Eccles, 713.838.5051, aeccles@byu.edu 4.3.2 Faculty Supervisor Dr. Gus Williams, 801.208.3137, gwilliams@et.byu.edu 4.3.3 Project Manager Mason Adamson, 509.551.1565, mason.adamson88@gmail.com 4.3.4 Design Team Leader Carter Livingston, 760.458.6449, carterlivingston1@gmail.com 4.3.5 Engineer 1 Greg Sanchez, 609.865.5282, greg.h.sanchez@comcast.net