REV90044 - Laserfiche WebLink

Home Browse Search

PAGE 2 JULY 8, 1996 DAN MATHEWS The seed mix and application rate for this is detailed in V-42. Following successful establishment of channel vegetation, and prior to final reclamation, ditch segments will be reevaluated to determine which segments, if any, will require additional sediment or erosion control devices. The final dttch ranamanrc of RP-5 i.e. the ditches not affected by final reclamation will be rip pped with graded, an ular, durable rocks. Any g aver rocks from the a9p rpm ~1II'68-moved. Simda~ry~ existing aver roek-theelyda - Jr9m these ditches will ke~move~ and reconstructs wi r a e ro However, the interim dttches will b'e controlled for erosions as outlined m 2. above. Also, the final ditch design will not apply to the western RP-5 ditch collecting undisturbed area diversion since this ditch area will be a part of the future refuse area 6 (RP-6). 4. We are proposing to use a Greenfix American WS-72 fiber blanket, or its equivalent, for erosion control. See attached product specification. This blanket is 10096 agricultural straw with aphoto-degradable netting on both sides and a minimum weight of 0.7 Ibs/ydZ. The seed mix specified in page V-42 will be used. I have amended page V-42 and V-44 of the permit as per your recommendation; Western wheatgrass has now been listed as 'Rosana' instead of 'Amur", 'green needle-and- thread° grass has been changed to needlegrass (stipa vindula) and the broadcast seeding rate has been changed to 60 PLS per square foot. Also, the seedmix used for cut and fill slopes (page V-41) will be used for the grass lined channels. 5. Figure IV-1 (a new figure) shows the specific design details of cobble dams. The existing cobble dams in Refuse area 5 will be removed, and cooble dams will be reconsfructed as per the design criteria. Temporary stabilization measures to be utilized to confrol flow velocities and minimize erosion have been discussed above in 2., and are included on page IV-24 of the permit. The temporary stabilization structure will be monitored and evaluated after each storm. Additional confrol measures will be undertaken if the existing measures are found to be inadequate. WFU will continue monitoring of these structures on a monthly basis once they are performing properly. The sediment deposited at the check dams or frays will be cleaned out once its level exceeds one-half of the consfructed capacity. The existing riprap in RP-2/3 and RP-4 will also be evaluated for its effectiveness. If the riprap is not performing properly, graded angular rocks will be used to replace the existing river rods. 6. In lieu of erosion control ditches along the face of the refuse piles, WFU proposes to use land imprinting as a method to control sediment and runoff velocties. Last year WFU used the sheep's foot compactor to imprint a portion of the north slope of the Refuse area 2-3 pile. To date, no additional cutting or rilling has occurred in this area.