Specifications include, but are not limited to: a) Bridge 1: There is an existing wooden bridge that is in very poor condition. This bridge will be removed without disturbing the banks of the stream it is bridging. There is no need to disturb the natural flow of water at this site to complete this project. Any existing bridge material within the banks should be cut off at the banks and left. The new bridge should then be installed spanning from top of bank to top of bank using the three 1’x4’x16’ timber mats to create a 12’ x16’ bridge spanning this stream. Refer to Appendix D for instructions on binding bridge sections together. Bridge approaches should be installed with a 1/12 pitch and span the full width of the bridge. b) Bridge 2: At this location there is an existing 30” RCP culvert that is beginning to fail. Adhering to wetland permit 2023-01200 (Appendix B and C) the 30” culvert will be removed along with surrounding materials returning the stream banks to their existing banks of approximately 14’. Care should be taken at the outlet not to remove any more of the existing header below the pipe than required so that the remaining stone can help with erosion control. After stream is returned to its normal bank width, it will then be crossed using another timber mat bridge. The bridge for this location will be made of three mats measuring 1’x4’x20’ creating a bridge that is 12’x20’. Refer to Appendix D for instructions on binding bridge sections together. Bridge approaches should be installed with a 1/12 pitch and span the full width of the bridge. A clean water bypass will be set up in this location to carry the water around the work area and back to the existing stream downstream. This bypass will need to be in place until excavation and bridge installation is complete and the steam bank is stabilized with sediment and erosion control. The selected vendor should indicate intended method of dewatering and BMP’s intended for stabilization upon completion in their proposal (see Section 8). . c) Culvert 1: This culvert is a new installation of a 12” HDPE culvert in an area with poor drainage but a fairly small drainage area. Depending on the time of year and weather conditions this culvert can likely be installed in the dry. Culvert must be installed with a downward slope to avoid pooling and sediment buildup within the pipe. Stone headers should be built to help protect culvert and road from washouts. Culvert should be installed so that there is at least 1’ of cover with the final grade of the road.
