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(c) 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. 1. 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 at the time of the test. 2. A hole for each test of approximately twelve (12") inches diameter (or as required for a maximum clearance of one-half (Z") inch between the -hole - and 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. 3. The test casing shall consist of a pipe that is a 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. 4. Fill the test bore to six (611) 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 is simulated. 5. 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 Public Works Department reserves the right to witness the test procedure. Exfiltration rates for designing the site drainage facilities shall be deter- mined by the developer's engineer from these tests based on percolation rate experienced at the elevation of the proposed system using a safety factor of 2 or greater. Alternate percolation or permeability tests procedures may be used if approved in writing by the Public Works Department prior to their use. (d) Hydraulic calculations for sizing channels, culverts, inlets, retention/detention ponds, pond discharge structures, and determining discharge rates and maximum water surface elevations. Coding. Words in • • -• • type are deletions from existing law. Words underlined are additions.