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HomeMy WebLinkAboutHonda DealershipHYDROLOGY / HYDRAULIC REPORT FOR HONDA DEALERSHIP LOCATED AT 16570 SO. HIGHLAND AVENUE CITY OF FONTANA, CALIFORNIA DR 06 -045R1 Prepared for AJ PIERCEY AUTOMOTIVE GROUP 13600 Beach Blvd Westminster, CA 92683 Prepared By. DRC Engineering, Inc. 160 No. Riverview Drive, Suite 100 Anaheim, CA 92808 (714) 685 -6860 Project No. 10 -110 July 1, 2010 aNhUiiF�iil �q FINAL HYDROLOGY / HYDRAULIC REPORT HONDA DEALERSHIP TABLE OF CONTENTS �01 SECTION 1.0 NARRATIVE Introduction Project Description Hydrology /Hydraulic Discussion Drainage System Description SECTION 2.0 HYDROLOGY CALCULATIONS Soils Map Hydrology Map Rational Method Calculations SECTION 3.0 HYDRAULIC CALCULATIONS Line A Line B Line C Weirs Catch basins 07 -685 Final Hydrology Report.doc a FINAL HYDROLOGY / HYDRAULIC REPORT HONDA DEALERSHIP SECTION 1, 0 NARRATIVE introduction Project Description Hydrology/ Hydraulic Discussion Drainage System Description 07 -685 Final Hydrology Report.doc FINAL HYDROLOGY / HYDRAULIC REPORT HONDA DEALERSHIP Introduction This report has been prepared to determine the post_ development storm wa ter ru quantities and the design of onsite storm water facilities including water quality management features for a proposed new car dealership to be located at 16570 South Highland Avenue in the City of Fontana, California. The proposed project is approximately 10.7 acres in size and is located immediately south of the 210 freeway between Cypress and Juniper Avenues. The project site is currently undeveloped and consists of vacant land and one public street, Highland Avenue. Proposed improvements will include three buildings, parking lot, landscaping, and associated underground utilities to serve the project. Project Description Existing Site Conditions: The site is an irregular shaped parcel approximately 9.5 acres in size. It is bounded on the north by Highland Avenue, on the west by Cypress Avenue, on the south by South Highland Avenue and on the east by an existing car dealership (Rotollo Chevrolet). The site consists of undeveloped land that drains in a southerly direction at a slope varying from 2.5% to 4.0 %. Existing vegetation consists of native grasses and one tree. There are no structures on the site. The site does not accept runoff from any offsite area. There is one culvert located at the southwest corner of the property that accepts runoff from Cypress Avenue and conveys it south across South Highland Avenue. Proposed Site Development: The proposed development consists of the construction of a new car showroom, a vehicle servicing facility, driveways, sidewalks, parking areas, and landscaping. As part of the project Highland Avenue is to be vacated by the City and incorporated into the site plan. The completed project will total approximately 10.7 acres after the Highland Avenue vacation, and dedication of additional right -of -way for the widening of Cypress Avenue Proposed on -site storm water facilities consist of catch basins, two underground storm drain networks, and two infiltration fields for water quality treatment. All of the storm water facilities will be privately maintained by the owner. Storm water in excess of the on -site infiltration capacity will be discharged to South Highland Avenue via parkway drains and allowed to flow easterly to an existing catch basin in front of the adjacent Chevrolet dealership. No off -site drainage facilities are proposed. Hydrology/ Hydraulic Discussion Background: The site is within the drainage area of the Juniper Avenue Storm Drain and Detention Basin System. The Juniper Avenue Storm Drain and Detention Basin System is a City of Fontana Master Plan of Drainage facility. The Juniper Avenue Storm Drain is designed to accept the ultimate Q100 from a fully developed watershed. As such there is no requirement to mitigate increased flows or volumes due to developing the site. Methodology: Hydrology calculations for the project were based on the San Bernardino County Flood Control District (SBCFCD) Hydrology Manual. The Rational Method was used to determine catch basin and pipe sizes. Advanced Engineering Software (AES) software was used to develop Synthetic Unit Hydrographs (in conformance with SBCFCD methodology) to evaluate infiltration fields. A 25 year frequency was used for all calculations. Pipe hydraulic calculations were performed using WSPG software from CIVILDESIGN. Catch basin and weir calculations were performed using Flowmaster software by Haestad Methods NO 07 -685 Final Hydrology Report.doc FINAL HYDROLOGY / HYDRAULIC REPORT HONDA DEALERSHIP Drainage System Description The drainage system consists of grate inlets and curb opening catch basins to collect surface runoff, underground pipes to convey the runoff, Stormtech storm water chambers to infiltrate the treatment volume, and reverse catch basins and parkway culverts to discharge peak flows. The WQMP for the project has been previously approved. The storm drain system is composed of Lines A through C. Surface runoff is collected in lines A and B and conveyed to an infiltration field by a system of inlets and pipes. The infiltration field will store 12,199 cubic feet of water. This entire volume will be infiltrated. Just downstream of the infiltration chambers we propose to install a structure that will block all flows up to the water quality treatment volume for these drainage areas. Higher flows will be allowed to pass via an elevated outlet, to the downstream portion of the storm drain. The calculations in this report assume that the infiltration field is full and that all the storm water is flowing through the drainage pipes. The areas draining to line C will pass through swales and join the main line of the storm drain downstream of the infiltration area for Lines A and B. The storm drain will then drain to a catch basin at the edge of the parking lot. This catch basin has openings on both sides of the basin. The opening on the parking lot side accepts runoff from area E and the opening on the opposite side discharges runoff to the street. The runoff from area E will drop into the bottom of the catch basin and be conveyed to the adjacent infiltration chambers which will store 676 cubic feet of water. These chambers are located such that the water quality treatment volume will be contained below the elevation of the outlet opening. As the chambers fill, runoff will accumulate in the catch basin until it reaches the elevation of the outlet. This reverse catch basin will outlet to a rectangular concrete surface channel that crosses a landscaped area and connects to a parkway drain. The reverse catch basin also accepts runoff from the storm drain and acts like a mini reservoir. Runoff will pond within the catch basin until it reaches the outlet opening on the backside of the basin. At this point runoff will exit the catch basin into the rectangular channel. The bottom of the catch basin will be perforated to allow any captured runoff to infiltrate into the soil. Sub area D1 will run through a swale and then connect to the concrete channel and combine with the drainage from lines A through C and area E1. The channel will eventually discharge into South Highland Avenue via the parkway drain. Area D2 will run through a swale and then through a separate parkway drain to the street. 07 -685 Final Hydrology Report.doc FINAL HYDROLOGY / HYDRAULIC REPORT HONDA DEALERSHIP SECTION 2, 0 A Hydrology Calculations Soils Map Rational Method Calculations Hydrology Map 07 -685 Final Hydrology Report.doc