7200 HARDESON RD 2016-01-01 MF Import

; w I� �a '� A lo cw w� 'f � hl !� c� tr Ii tt �� �s i� � Soil bioengineering techniques have been used extensively in Europe but until recently have been less commonly applied in the United States. Robbin B. Sotir & Associates (RSA), an internationally recognized specialty soil bioengineering firm, may be used as a design consultant if soil bioengineering solutions are selected for the project. Soil bicengineering diffecs trom revegetation in that the former provides immediate streambank sWbility; that is, there is no necai to wait several growing seasons to allow for adequate root development, as is the case with revegetaHon. Bank stability u accomplished by placing plant materials in a con(iguration whereby the stems and trunks of cuttings pmvide protection from erosion for streambanks and slopes. For this project, furiher short- term stability (flve to 10 years) will be provide.i by the use of natural geotextile fabrics that have been included in the design. Approximately 825 feet of the existing channel µould be restored within a 60-foot corridor adjacent to Hardeson Road. Approximately 2801ineal feet of tlie southern portion of the existing channel would be relocated closer to Hardeson Road. Therefore, this section of the channel would need to be recreated. The balance of the channel would be restored in pla:e, with limited or no relocation from the existing course. The channel would be graded to match the proposed channel restoration and realignment project to the north. The width of the stream cottidor and the channel configuration wouid vary depending upon whether the channel is relocated and restored or only restored. in the relocated sectior., ,} •�` the stream corridor would be 10 to 15 feet wide and approximately 2 feet deep with a stream ;'�� ' channel5 feet in width (Figure 2).�In the restored reach, the existing stream course would betc�° �^� preserved, aithough addition of an overElow channel 'u probably necessary to reduce Flood (�� '' � depttu and convey the 100-year Flood1The exact conflguration of the channel, in both , �vµ i' . reaches, will be determined during flnal design. Figures 3 and 4 present a range of possible � r�� ; �� cross-sections for the proposed stream corridor. �� _ „�� i A The restored stream channel is expected to be equal in length to the existing channel. �y The stream corridor would be vegetated to form a thick stand of native vegetation that �� shades the stream, and provides wildlife habitat. Trees, rather than shrubs are et�np asized `j in the planting efforts ro reduce the potential for decreasing channel conveyance capacity. i` The channel gradient would be spproximately 2.5 to 3.0 percent. Near lhe north property � line, the sewer line will be protected by placing rock or a structure; details wiil be developed during the fuial design process. If the banks in this short reach are to be lined with rock to , y resist erosion, joint planting with live stakes may be incorporated to establish vegetation. pa � 7 �