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<br />...- <br /> <br />f <br /> <br />""A <br />""'1 <br />,..;:~~"'1 <br /> <br />-ID.....-' <br />..;~.-..:i <br />,,,,,. <br /> <br />','<:\ <br />-'J <br /> <br />Revised <br />7-14-87 <br /> <br />Dam safety Branch <br />Design Review Unit <br />Policy Book LSWT & ECD <br /> <br />Page 2 <br /> <br />H. Excavation within the water storage basin is allowed as long as the <br />following conditions are met: <br /> <br />a. Excavation within the basin and at the upstream toe is allowed <br />provided the bottom of the excavated area is parallel to the slope of <br />the stream or natural channel and the bottom of the cutoff trench <br />under the dam is a minimum of four (4) feet deeper in elevation than <br />the lowest point within the excavated or ponding area. <br /> <br />b. Exposed pervious layers within the ponding area shall be blanketed <br />with two (2) feet of impervious material. <br /> <br />c. The maximum storage capacity of the reservoir does not exceed ten <br />acre-feet. or in case of erosion control dams. the maximum storage <br />capacity below the outlet does not exceed two acre-feet. <br /> <br />I. The law pertaining to LSWT does not apply to water "pits" and they should <br />not be filed as LSWT/ECD. [per A.R. Owens, 1965] <br /> <br />J. <br /> <br />Riprap slope protection will not be required during initial construc- <br />tion. If time shows that slope protection is found necessary. the owner <br />shall install riprap. <br /> <br />K. Spillway widths shall be in accordance with our standard specifications <br />except where drainage areas exceed the tables, the spillway shall be <br />designed for the run-off from a 25-year, 24-hour rainfall. The spillway <br />shall have two feet of residual freeboard and the maximum velocities <br />shall be limited to 3.5 fps for earth spillways. Higher velocities will <br />be allowed for more erosion resistant materials. <br /> <br />L. Departures from the standard specifications and spillway design criteria <br />will be accepted. provided the design is prepared by a professional - <br />engineer and approved by this office. The four foot minimum freeboard' <br />requirement will not be waived. <br /> <br />M. We will not accept for filing purposes, any "AS-BUILT" LSWT/ECD <br />application which does not meet the minimum standards. or in lieu <br />thereof, has not been designed by a professional engineer. Applications <br />will be returned to the owner with a copy of the specifications for <br />structural modifications to bring the dam into compliance. <br /> <br />SAS :bab/1137I <br />