Laserfiche WebLink
<br /> <br /> <br /> <br /> <br /> <br /> <br />DivNrsion T~rrat:~ <br />q d~.versi~~n terrace is a channel with a suopor•ting ridge on the <br />lowear side constructed across the slope. !t is used to reduce <br />slope lengths, break u <br />waterr• to stable outlets <br />grades nray be variable, <br />types and vegetative cover <br />ch arrnel side slopes for <br />per•nranent ones. <br />Oraf:sad Waterways <br />p concentrations of runoff, and to move <br />at a non-erosive velocity. Channel <br />with the allowable velocity for• the s~~il <br />determining maximum grade. Maximum <br />temporary divers i~~n ar•e 1:1 and 3:1 f~~r• <br />' Thea>e ere waterways shaped or graded and established in suitable <br />vegetation to dispose of runoff water without danraoe by erosion. <br />Thie> practice applies to sites where added capacity andlor• <br />' vege~t ative protection is required to control erosion resulting <br />from concentrated runoff. Supplemental nreasur^es may be required <br />such as grade control structures and rubble or log lined channel <br />' bottoms. Minimum design capacity should accommodate peak r•unt~ff <br />from a 24 hour, l~D-year frequency storm. Design velocity is <br />based on s~-r11 type, duration of flow, and type and quantity ~~f <br />vegertat ion. <br />' 6tre~w Mulching <br /> Bare+, n~~n-vegetated slopes can erode quickly and should be <br /> vegertated if final reclamation does not follow in the same <br /> seae~on. Straw mulching nray be broadcast by hand, and aids in <br /> establishing good vegetative cover and provides temporary erosion <br />' control until Sufficient plant co ver develops. On steep slopes, <br /> or• aih ere exposed to strong winds, mulch should be se c ur•ed to <br /> prevent its being washed or• blow n away. This can be done by <br /> spraying with asphalt or• chinking in with a light disk, nelther• <br /> of rihich inter•fer•es with seedling growth. <br />' Rubt~le Line Channels/Chutes <br />Wher~•e concrete rubble is available, rubble lined channels are an <br />efficient method of permanent erosion control. Logs from tree <br />' cleair•1ng nray also be used to stabilize channels. The logs will <br />be a~ nrininrum of eight inches in diameter and placed perpendicular <br />to the water flow. Used in combination with vegetative side <br />' slopes, the rubble or• log section is to be designed to handle the <br />greater of either the base flow or runoff from a one-year <br />frequency storm. Flow depth of the r•u bble section shall be a <br />minimum of .S feet. Rock size used is dependent of the channel <br />design depth and slope. Logs of sufficient dianret er• may be used <br />in conjunction with rubble. <br /> <br />E - 2 <br />