5920 GLENWOOD AVE 2016-01-01 MF Import

� � � ro A ' C . . t H�y N � +. H Z N K n �, x ro � � CONSTRUC'PIOI! OF VEGE7'ATL•'D SWALES N M � � � General Considerations: � � R The vegetated swales should be constructed early in the M � construction sequence in order to give vegetation a chance � y � to establish before the swales are necessary as a part of � y the permanent storm drainage system. As a general rule, � o y silt-laden construction runoff �hould not be routed through � � � completed vegetated swales. y o vyi To prevent the swale from becoming a sediment rource, it must be stabilized immediately after it has been graded. One of two methods may be chosen for immediate stabilization of the swale - sodding or the use of an erosion control blanket. Depending upon the manufacturer, thca price of stabilizinq the swale with erosion control blanl:ets may be slightly more than stabilization with sod. However, use of a blanket may result in more successful establishment of veqetation in the swale, therefore resulting in more efficient pollutant removal. Later .maintenance problems and costs would also Ue reduced. Erosion control blankets may become a requirement �'�� in the future if field studies indicate that a significant �� advantaqe exists with their use. The erosion control blanket chosen should be recommended by it�.� the manufacturer for low velocity channel use. In general, �� a suitable blanket is made of wood excelsior or coconut fiber held together with a slowly degrading or non-degrading mesh. � s I �� Construction of swales using sod: � Prepare to sod the swale immediately after it has been raded. Roughen the bottom and sides of the swale by �t� tilling or raking, place 4" of topsoil, and fertilize with an appropriate fertilizer at the rate of 7 lbs per 1000 , square feet before laying the sod. In general, use a 10-20- r�� , 20 (N-P-K) fertilizer. liowever, use a non-nhosphorus containin fertilizer if the swale is bein constructed in �i i the Silver Lake Drainaae basin. , I "� Sod the swale immediately after the sides and bottom of the l "�t�' swale have been prepared. Lay sod to a minimum of 0.75 feet � of vertical depth. If the swale is constructe3 between Saptember 1 and April 1, sod the entire swale area. Anchor the sod in place in the bottom of the swale and to 0.75 feet of vertical depth with stakes, metal staples or other means.