2006 hydrology manual los angeles county

Updated 2011 indy huff distributions added in hydrocad10 build 21. Location and description of property figure 1 shows the proposed location of the proposed avanti south residential development. More detailed information related to class numbers and their. The standards set forth in this manual govern all hydrology calculations done under public works jurisdiction. Each area was analyzed for acreage, impervious cover, and time of concentration according to the rational method. E appendix a and b california public utilities commission.

The drainage areas for the proposed development were determined based on the proposed streetland flow areas and the existing offsite topography. The 1986 orange county hydrology manual and its 1996 addendum have been calibrated to local watershed conditions. The rainfall at this specific project site is determined to be 6. Variation of the huff distributions from indianapolis stormwater manual 51095.

The modrat and mora software programs both do modified rational hydrology calculations. Woodcrest engineering obtained the source code and developed it for personal computers. This method is appropriate because the project does not involve an area larger than 40 acres. The rainfall isohyetal for the project site falls under 6. Hydrology appendix c soil identification table number name original name 2 altamont clay loam a 3 chino silt loam cs1. Hydrology the project site is located within the downtown newhall specific plan dnsp and within the proposed.

Modified rational method to calculate the required time of concentration. There are runoff coefficient curves in the manual for each of the soil types. This section of the draft eir evaluates the impacts related to hydrology and water quality, and evaluates. Rainfall and soil characteristics for the project site are given in isohyetal map figure lacdpw 1hi. The first edition of the sedimentation manual 1993 has been reformatted to be consistent with the 2006 hydrology manual. This second edition of the sedimentation manual contains updated references to the 2006 hydrology manual and does not share appendices. The burned runoff coefficients versus rainfall intensities were input into the modrat program as new soil types. Before starting a hydrology study on the site indicated. Solano county water agencys office is currently closed to the general public due to the covid19 situation. Technical info submitted by anonymous on january 26, 2017.

Precipitation, runoff, water levels and water conservation are detailed in annual reports developed electronically since water year 19571959. A watershed is the land area where water collects and drains onto a lower level property or drains into a river, ocean, or other body of water. The software packages accepted by public works are found in chapter 15 of the 2006 hydrology manual available online at. Before starting a hydrology study on the site indicated above. Rainfall distribution tables hydrocad stormwater modeling. The standards set forth in this manual govern all hydrology calculations done under pub lic works jurisdiction. Station square south hydrology report prepared by monrovia, california khr associates 5 3. Storm frequency conversion factors based on rainfall frequencies. The results of the modeling show that there will be an increase in the peak hourly flow rate with the proposed project.

Where the runoff coefficient is the percent that runs off from the impervious area plus the percent that runs off from the pervious area. Resolution declaring a countywide water supply and conservation alert, adopted august 5, 2008. Porter county indiana, 1st, 2nd, 3rd, 4th quartiles. As a soil scientistgis specialist with the usda natural. Examples provide guidance on using the hydrologic methods. A rational method analysis was performed and the appropriate calculations are provided herein. Report on the calibration analysis for the san diego county hydrology manual, may 2007 if you have trouble downloading the manual, please contact anthony barry at 8586942707.

If you see a county storm drainage system in need of maintenance, contact the county department of public works field operations staff at 619 4431260 weekdays. In general, peak flows from urban and small undeveloped watersheds for use in channel design can be evaluated using our modified rational method and programs vcrat 2. The rainfall at this specific project site is determined to. The proposed drainage and roof runoff will need to be collected and treated through effective uses of bmps such as a series of flowthrough planters. However, please note that certain information may only be available to city employees. The primary goal is to provide 100year flood protection for all. Design hydrology methodology link to manual and vcrat programs please see the 2017 update of the vcwpd hydrology manual and our design hydrology programs through the above link. The manual contains current standards and procedures, examples, runoff coefficient charts, and maps of rainfall isohyets and soil types. F6, the existing stormwater runoff rate at the project site is approximately 152.

Runoff rates were calculated for 50year storm events. More detailed information related to class numbers and their meaning can be found. They provide guidance in estimating peak discharges and volumes of storm water runoff for the design of flood control facilities and flood plain determination. The results of the modeling show that there will be an increase in the.

We assigned an impervious factor of 6% which is the same designation used by ackerman et al. The methods from the sedimentation manual have not changed. Countywide construction contracting policy manual design manuals hydraulic. Contemporary and historical hydrologic analysis of. Storm frequency conversion factor q x k q 11 2yr 5yr 10yr 25yr 50yr k 0. Methodology the rational method and modified rational method are empirical computation procedures for.