10705 HOLLY DR 2018-02-01 - Laserfiche WebLink

. , � � Technical Memorandum—Habitat Assessment for Holly Drive Lift Station Upgrade December 23, 2015 bounded on the west by Swamp Creek headwaters approximately 20 feet outside the fence line. The lift station is located within the 100-foot stream buffer and all of the proposed lift station improvements will be located within the buffer established for this Type F stream by EMC 19.37.170. The site is surrounded on the north and east by houses and backyards with assemblages of plants and animals typical of the suburban Puget Sound basin. Overstory at the lift station includes cottonwood, alder, maple, and a western red cedar and Douglas fir. Understory plants include non-native holly, bamboo, and Himalayan blackberries. Native riparian species present include willows, vine maple, salmonberry, water parsley, and swordfern. It should be noted that the western portion of the paved parking lot on the lift station site has been inundated by shallow floodwaters at high flows. There is a small, intermittent stream that flows east to west along the southern end of the lift station parcel along the utility corridor that contains the sewer mains serving the site. This intermittent stream meets Swamp Creek just to the southwest of the fence line. Bamboo growing in the backyard of one of the homes along the corridor has spread into the floodplain of Swamp�Creek. Further, ornamental holly from the lift station's perimeter landscaping has also invaded the riparian corridor. The project site is located approximately 10 stream miles above the Swamp Creek confluence with the Sammamish River. It is approximately 2 miles above the nearest recorded site of salmonid usage documented in the WDFW Salmonscape Database (coho and sockeye) downstream of Lake Stickney. Chinook salmon have been observed approximately 1/4 mile below this point, and steelhead have been modeled to be present at this point,just over 2 miles downstream of the project area. The nearest documented presence for bull trout is more than 10 miles below the project area in the Sammamish River. ANALYSIS OF EFFECTS Direct Effects Direct effects associated with construction of the proposed wet well, piping, and associated lift station improvements will be minimal, as all work will occur within the existing fence line and BMPs for the control of sedimentation and erosion will be implemented. Construction noise will be limited to operation of diesel-powered excavators, loaders, and trucks for a period of approximately 4 months during the summer of 2016. The WDFW Priority Habitat and Species Map prepared for the project on December 14, 2015, indicates that there are no noise-sensitive ESA-listed species present within 1 mile of the project area, so that noise associated with construction will have no adverse impacts on listed species. ,f i'�� /�