ARCHIVED REPORTS_1999 - Laserfiche WebLink

Home Browse Search

GEO►SYNTEC CONSULTANTS Page i of Written by: JOE TAM Date: 22 -Oct -99 Reviewed by: Date: IO ZZ Client: Allied Waste Project: Forward Landfill Project/Proposal No.: WS0264 Task No.: 01 SURFACE WATER MANAGEMENT SYSTEM CALCULATIONS FORWARD LANDFILL ST CTON,CA The purpose of these calculations is to design the surface -water management features to be constructed on the landfill after closure and on the site at Forward Landfill in Stockton, California. Surface water management features are designed to comply with the following regulations: • California Code of Regulations, Title 27, Class III Landfills; and • San Joaquin County Hydrology Manual (1999). Design Flow Rates The computer program "HydroCAD", Version 5.11 [Applied Microcomputer Systems, 1999] was used to estimate design storm -water discharge rates, which were subsequently used to size the drainage ditches and culverts. HydroCAD is a hydrograph routing model designed to specifically handle time varying flows and outputs results based on the most -used capabilities of the Soil Conservation Service Technical Release 20 (TR -20) [USDA -SCS, 1982] and the Soil Conservation Service Technical Release 55 (TR -55) [USDA -SCS, 19861. The assumed drainage subareas and drainage structures are shown on the attached Figure 1. Ditches Ditches are designed to accommodate the peak discharge from the 100 -year, 24-hour storm, in accordance with California regulations for Class III landfills [Table 4-1 of Title 27, CCR] with a minimum freeboard of 0.5 ft. The design storm for the San Joaquin County will be used. Drainage ditches are designed as "v" -ditches (bottom width = zero). The allowable discharge in the drainage ditches is estimated using Manning's equation [Roberson and Crowe, 1985], as shown below: Q = 1.49 ARYSY (1) n where: Q = Discharge (cfs) n = Manning's roughness coefficient MALLMI)WASTETORWARD WMU BICLOSURE PLAN\DRAINCALCS\SW2.DOC