1987-12 - Laserfiche WebLink

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R source. A one foot interval contour topographic map of develop- ment area including offsite area of sufficient size to indicate the general neighboring elevations.. pigs drainage patterns and transition grades shall be provided. Justification for wet season water table assumptions shall be provided. (2) Hydrologic calculations for determining existing and proposed stormwater runoff. (3) Hydraulic data including receiving water stages, stage -storage and stage -discharge data for proposed retention and/or detention facilities, and percolation test data as per the following procedure: (a) The test holes shall be located as close as possible to the proposed location of exfiltration trench or other percolation facility (vertical and horizontal) and, if critical, to a depth two (2') feet below the water table (MSL) at the time of the test. (b) a hole for each test of approximately twelve (12") inches diameter (or as required for a maximum clearance of one-half 0") inch between the hold and the test casing) is excavated to the required depth and the casing is lowered into the hole with a minimum of twelve (12") inches extending above the surface of the grade. (c) The test casing shall consist of a pipe that is at least eight (8") inches in diameter with perforations in approximately the bottom seventy-five (75%) percent of the length as measured from the surface. The bottom of the casing shall be pointed. Exfiltration increments shall be measured with a suitable gauging device. (d) Fill the test bore to six (6") inches above the surface of .the existing grade and run the test no later than two (2) hours after the level has exfiltrated to below surface of existing grade. In all cases test runs are to start only after the first two (2") inches have exfiltrated. If a dry season condition exists, the test shall begin when the soil is moist and a wet season condition is simulated. (e) Run tests for at least thirty (30) minutes and record at least the date, weather, project name, name of person conducting test, test number, location on site, sketch of hole and casing, groundwater conditions, incremental drop and time, and subsurface soil information. Information shall be tabulated and attested to by a registered professional engineer, licensed to practice in the State of Florida. The County Division of Public Works must be notified at least twenty-four (24) hours in advance of the tests being conducted and reserves the right to witness the test procedure. Exfiltration rates for designing the site drainage facilities shall be determined by the developer's engineer from these tests based on percolation rate experienced at the elevation of the proposed system using a