BCRI_AdditionalScope_of_Work120519.doc

Burnt Cabin Riparian Improvement, Road 206 Additional Information Stream Channel Relocation Information Channel Excavation and Floodplain Development. Burnt Cabin Creek will be relocated with multiple channel section excavations. The new channel sections will be excavated from their downstream end, upstream to where they tie in with the existing channel. Three types of channel cross sections will be excavated, pools, glides and riffles. The transition between these cross sections will be blended with even grades and transitions. Excavated material from the channel and floodplain areas shall be used as embankment to develop channel, floodplain, and used as backfill for the existing channel. Priorities for existing channel backfill will be at the upstream confluences of the existing channel and new channel where the channel switching process occurs. Additional areas of the existing channel will be backfilled as staked by the Contracting Officer.

Channel Switch. The execution of the channel switch shall only occur between July 15 and October 1st of any given year. The Contractor shall provide written notice to the Contracting Officer a minimum of 5 working days in advance before the channel switch will be allowed. Once approval has been granted by the Contracting Officer, the Contractor shall work directly with the Contracting Officer Representative (COR) over a 3 to 5 working day period to slowly increase the volume of water into the new channel. During the 3 to 5 working day period of time, the government will transfer aquatic species from the old channel to the new channel.

Existing Channel Backfill and Sloping. After the channel switch, the existing channel will be backfilled with excess material remaining from new channel excavation and floodplain development. Priority for the embankment material will be starting at the upstream end of the existing channel and placing embankment material to fill the entire channel for approximately 200 feet. Remaining embankment material shall be placed at locations in the existing (newly abandoned) channel to eliminate vertical or undercut slopes in an effort to promote vegetative recovery. The existing channel shall have the vertical or near vertical stream banks sloped to 1:3 where backfilling has occurred or where the hillslope meets the channel. During sloping work, the woody vegetation that may be present on top of the vertical or near vertical banks shall have the root system kept intact as much as possible to transplant on the slope. In areas where woody vegetation (conifers) is too large to successfully transplant, they shall remain in place on top of the bank. Use excavated backfill material, existing stream bottom material, or other bank material to create the appropriate slope.

Removal of Structures and Obstructions. Due to the history of past timber harvest activities and associated railway, the possibility exists that foreign objects such as cable, rail, pulleys, etc., may exist. Foreign objects found within the project boundary shall be subject to AGAR 452.236-73 (Archeological or Historic Sites (FEB 1988)) until otherwise determined. After proper authority determination, non-archeological or non-historic items shall be removed from National Forest System Lands and disposed of by recycling or transporting to a licensed landfill that complies with all Federal, State, and local laws.

Streambed Stability Rock. Streambed stability rock shall be installed in the riffle sections of the new channel to provide larger less mobile particles in the riffles. The rock will be 8 -12 inches on its shortest side and shall be durable for mechanical handling and placing without fracturing. The rock shall be individually spread in the riffles. The streambed stability rock will be spread in an offset pattern with the rocks having a spacing of 2-3 feet apart across the channel and lengthwise in the channel. The rocks shall be mechanically pressed flush into the channel bottom of the finished grade riffles avoiding breakage.

Habitat Enhancement Structures. Logs and logs with rootwads delivered from the road construction and removed during excavation of the new channel or floodplain will be utilized in the stream channel and floodplain for habitat enhancement structures. Habitat enhancement structures will be installed throughout the project area and shall be staked at the appropriate time as work progresses. Rootwad barbs will be utilized throughout the stream channel and installed prior to debris catchers which will be utilized to provide anchoring or locking opportunities for the placement of habitat logs on the floodplain and stream channel. Staking for the debris catchers will be conducted as work progresses from downstream to upstream to minimize the need for re-staking. Habitat logs will be placed on the floodplain, scarified access routes, and others will be anchored or locked around debris catchers and other existing opportunites. Some will be interacting with the stream channel while others are providing micro-sites for planting opportunites. Habitat logs may be placed as individual logs or in aggregates. Due to the large number of different configurations for habitat logs the Contractor will work directly with Contracting Officer for log placement. Individual habitat logs will not be staked. The Work Site List provides an overview of the location of the majority of habitat logs but is not all inclusive due to the potential application on scarified access routes.