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HomeMy WebLinkAboutSWP273218(6) SEPA Environmental Review Application Strander Boulevard Extension Project City of Renton September 2004 i - 4 - 1 PROJECT NARRATIVE ' DEVELOPM CITY OF REENT PLgNNTONNING ' OCT 1 12004 RECEIVED ' 4- 1 ' Pert i��. 4 Project Narrative ' Project Name The proposed project is called Strander Boulevard Extension and SW 27`h Street Corridor Improvements. The purpose of the project is to improve travel speed, reliability, and ' access in the north Renton/south Tukwila area. The project will create a cross-valley link between West Valley Highway(SR 181) and Oakesdale Ave. SW with a single roadway overpass will be constructed over both a relocated Union Pacific Railroad (UPRR) track ' and two Burlington Northern Santa Fe Railroad (BNSF) tracks. From Oakesdale Ave. SW to East Valley Road, SW 27`h Street will be widened with pedestrian facilities and ' landscaping added. Figure 4-1 shows the project area. ' Project Size and Location This project will encompass approximately 100 acres between West Valley Highway (SR 181) and Oakesdale Ave. SW that links Tukwila, Washington to Renton, Washington. This project study area is located in Section 19, Township 23 North, Range 5 East; Sections 24 and 25, Township 23 North, Range 4 East; Section 30, Township 23 North, ' Range 5 East(see Location Map, Figure 1). Renton is located at the south end of Lake Washington on the edge of metropolitan and rural King County. Figure 4-1 shows the location of the project. The study area is sideways T-shape. It includes the area between the west side of the Interurban Trail and the east side of the Burlington Northern Santa Fe (BNSF) railroad ' track. The study area is wider in the vicinity of Strander Boulevard because it is possible that the trail would be moved. The southern boundary is south of a railroad spur heading northwest from the Union Pacific Railroad (UPRR) mainline (the spur that crosses the ' Green River,not the short spur that serves adjacent businesses), which is about 1,700 feet south of Strander Boulevard. The spur would be the approximate takeoff point for a new UPRR mainline track that would replace the existing track. The new track would parallel the existing BNSF tracks. On the north end, the study area extends just past 1-405 where the UPRR track begins to parallel the BNSF tracks. Land Use Permits Required The following permits or approvals will be necessary for this project: 4-2 ' Perteet Inc. Permit Authority Name of Permit Federal (FHWA) National Environmental Policy Act (NEPA) Environmental Classification ' Summary (ECS) and Categorical Exemption ' Federal (ACOE) Clean Water Act(CWA) §404 permit State (WDOE) CWA §401 Water Quality Certification ' State (WDOE) NPDES (CWA §402) general construction permit ' State (WDOE) Hydraulic Project Approval ' City of Renton Shoreline Substantial Development Permit City of Renton Right of Way Use Permit ' City of Renton Building and construction permits ' City of Tukwila Shoreline Substantial Development Permit City of Tukwila Sensitive areas and construction documents ' reviews ' Request for Shoreline Substantial Development Permit from the City of Renton The project area and the roadway will cross directly over Springbrook Creek. Because the existing box culvert was sized large enough when it was installed to fully accommodate ' the road expansion,the only work that might occur below the ordinary high water mark of Springbrook Creek would be the replacement of the two existing stormwater outfalls. However, construction of roadway will occur within the 200-foot shoreline jurisdiction, as well as over the creek. Accordingly, a Shoreline Substantial Development Permit will be needed for the project, and shoreline permit review is requested as part of this submittal. The ordinary high water mark (OHWM) for Springbrook Creek ' (approximately 15.0 feet elevation above mean sea level) has been added to the site plans in Section 10 of this application as well as the Flood Hazard Plan in Section 17. ' Request for Variance (Deferral of Approval for Wetlands Mitigation Plan) from the City of Renton ' The development of a final Wetlands Mitigation Plan will take more time than will be provided in this environmental review process, in part due to the need for some further design work and decisions. As is indicated in the Conceptual Wetlands Mitigation Plan ' (attached), a commitment is being made to meet the full wetlands mitigation requirement Z 4-3 ' Perl "*Inc. ' per the municipal code. A variance is requested to defer the final approval of the wetland mitigation measures. A final Wetlands Mitigation Plan will be submitted prior to ' construction Phase II (the first phase that incurs the wetland impacts). The City of Tukwila will review and approve the mitigation plan as it is developed, as per other project documents. Zoning Designation and Current Use of Site Four different Cityof Renton zoning designations are within the proposed project area. g g P P P J Figure 4-2 shows the city zoning map for the project area. From the western city limit eastward to the intersection of Oakesdale Avenue SW and SW 27th Street, the property is zoned Commercial Office (CO). Proceeding eastward along the north side of SW 27th ' Street to Lind Avenue SW, the property is zoned Industrial- Heavy (IH). Along the same segment on the south side of SW 27th Street, the property (owned by the City of Renton) is zoned Resource Conservation (RC). On the north side of SW 27th Street from Lind ' Avenue SW to East Valley Road, the property is zoned Industrial- Light (IL). Along the same segment on the south side of SW 27th Street, the property is designated as Industrial- Medium (IM). ' In Renton, commercial and light industrial land uses are located along the proposed project corridor, in particular on the north side of SW 27`h St. and near its intersection ' with East Valley Road. A large portion of the land south of SW 27`h St. and the proposed Strander Blvd. extension are undeveloped and depicted as Resource Conservation on the Renton zoning map. There are no residential or recreational land uses near the proposed project area within Renton City limits. The zoning classifications in the City of Tukwila are the same as the comprehensive plan ' designations (e.g., Tukwila Urban Center and Commercial Light Industrial). The Tukwila Urban Center is the specific area characterized by high-density regional uses that include commercial uses, offices, light industry, warehousing, and retail uses. tThe Commercial/ Light Industrial is an area characterized by a mix of commercial, office, or light industrial uses. Commercial areas consist of offices, lodging, ' entertainment, and retail activities. Light industrial areas are characterized by distributive and light manufacturing uses with supportive commercial and office uses. In Tukwila, land uses surrounding the intersection of West Valley Highway and Strander Blvd. and north up to 1-405, consist of commercial uses catered to the traveling public, including restaurants, gas stations, and convenience stores. South of that intersection the ' land uses, while still containing commercial uses, are more light-industrial commercial uses such as manufacturing. There are no residential land uses near the proposed project area within the Tukwila city limits. A short portion of the Interurban Trail, a recreational ' use, is located near the western terminus of the proposed project and would likely be affected by it. ' 4-4 ' Perteet Inc. Special Site Features IWaterbodies The proposed project area is within the Duwamish River/Green River watershed, WRIA #9. The major water bodies near the proposed project area are the Green River and ' Springbrook Creek(stream number 09-0005). The Green River flows south to north, and is located west of the proposed project area along the west side of the West Valley ' Highway. The Green River's name changes to the Duwamish River at river mile 11, where it converges with the Black River. The'Duwamish River flows into Elliott Bay in Seattle. Springbrook Creek flows south to north and bisects the project area along 27th Street SW between Oakesdale Ave. SW and Lind Ave. SW. It flows to the Black River Pump Station located near the intersection of I-405 freeway and the Valley Parkway. The pump station discharges into the Green/Duwamish River. This pump station has defined pump capacity restrictions, which regulate the flows in Springbrook Creek. SW 27`h r Street will be widened on either side and across Springbrook Creek, where an earlier City of Renton project replaced old, undersized arch culverts with a new, greatly enlarged box ' culvert. This culvert was sized large enough(per the modeling for the East Side Green River Watershed Project, 1997) to accommodate the future expansion of SW 27`h St., and so will not need to be further modified. ' Other water bodies in or adjacent to the proposed project area include drainage ponds and drainage ditches, and 29 wetlands that have been delineated in the project area. Fourteen of the twenty-nine wetlands or their buffer areas may be affected by the proposed project. Of these, 13 wetlands may have buffer impacts and five may have wetland impacts. In summary, 9 wetlands only have buffer impacts, 1 wetland only has wetland impacts, and ' 4 have both wetland and buffer impacts, for a total of 14 wetlands. Approximately 2.02 acres of wetland impact would result from roadway improvements. In addition, 3.90 acres of buffer impacts would result. Wetland impacts from fill placement would result in ia decrease of wetland functions and values performed. ' Floodplains Portions of the project area lie within the floodplain. Springbrook Creek,which the project crosses, is a Federal Emergency Management Agency (FEMA) floodway. No fill will be placed in the FEMA floodway, and no additional constriction of flow in the floodway will result from this project. The existing box culvert will pass the existing and future 100-year flood flows. However, construction and associated fill will be placed ' below the 100-year flood elevation in the vicinity of Springbrook Creek. ' During construction of the proposed action, location(s) should be identified in the Springbrook Creek drainage upstream of the SW 27th Street crossing for the development of approximately 2,430 cubic yards of compensatory storage. The ' compensatory storage could be achieved by removing dirt from below the 100-year floodplain elevation and transferring the volume to a receiving location above the 100- year floodplain elevation (future conditions) of 19.2 feet. ' 4-5 ' Perteet Inc. ' If unmitigated, floodwater storage capacity would be reduced accordingly. This would result in some additional backing-up of water in the upstream tributaries and ponding of ' excess water, and contribute to a slightly higher flood elevation and frequency in these upstream areas. Geology The proposed project crosses recent fill and soft and loose deposits that are susceptible to ' liquefaction and its associated effects, and the entire project area is within a high liquefaction susceptibility zone. The effects of the potentially liquefiable soil beneath the proposed action would likely include reduction of vertical capacity and a reduction in lateral support/increased lateral soil pressures on the proposed foundations and ground settlement. rCurrent design-level earthquakes could occur during the life of the project, causing liquefaction. The effects of liquefaction may include decrease of bearing capacity for existing shallow foundations, ground surface settlement, reduction in lateral and vertical capacity of new deep foundations, cut slope and fill instability, and lateral deflection of existing utilities. Liquefaction alone could cause large ground settlement. ' Nearly all of the potential seismic impacts could be mitigated by proper design and standard construction procedures. Liquefaction and, in particular, liquefaction-induced settlement may require nonstandard construction procedures to partially mitigate; however, these procedures, although nonstandard, are not uncommon given current seismic design criteria and earthquake engineering technology. Soil Type and Drainage Conditions 1 The geological and soil conditions for the site are described in detail in the Geology and Soils Technical Discipline Report, Strander Boulevard Extension Project, (May 2004). The soils encountered during reconnaissance geotechnical boring installations included 1 eight primary units including a fill unit, Peat/Peaty Deposits, Estuarine/Overbank Deposits, Cedar River Alluvium, Beach Deposit, Duwamish/Green River Alluvium, Cedar River Alluvium—Gravel, and the Vashon Advance Outwash. The human-placed fill material (Hf) comprises the top geological unit, which consists of varying composition was placed in depressions or for railroad embankments. The permeability of the fill material is variable. The largest deposits of fill material are the UPRR and BNSF railroad embankments near the western end of the proposed alignment. A peat layer(Hp) about 1 to 3 feet thick was encountered between about elevation zero and 10 feet in borings B-101 through B-103, B-105 and B-106, B-108 ' through B-110, and B-112, which indicates a somewhat continuous peat deposit The fill quantities were updated since the publication of the Floodplains Discipline Report, May 2004. 4-6 ' Perteet inc. ' west of Oakesdale Avenue SW. Logs were encountered in boring B-I I I between 22 and 27 feet below ground surface. A more continuous peat layer about 4 to 5 ' feet thick was encountered near the same elevations in all the borings east of Oakesdale Avenue SW (B-201 through B-205). The Green/Duwamish and Cedar Rivers deposited this fine-grained floodplain and deltaic unit (He). This unit was not overridden by glacial ice. It consists of very soft to medium stiff, slightly fine sandy, clayey silt and silty clay, with scattered organics and discrete peat lenses and layers. This unit has a relatively low permeability. It is found throughout the site, in every boring drilled along the proposed alignment. The Cedar River Alluvium (HaQ is a fine to medium alluvial unit that was deposited from the ancient Cedar River after the last glaciation of the Puget Lowland. The unit consists of loose to very dense, sandy gravel and gravelly sand,and contains scattered organics and numerous lenses and layers of loose silt and fine sand, and is locally clayey. This unit is comprised of rounded to ' subrounded particles of crystalline rock, typical of glacial deposits in the Cedar River valley. This unit has a range of relative permeability from low to high. Based on borings B-107 and B-109, this unit has a maximum thickness of about 50 feet. The unit appears to pinch out to the west, as indicated by the soils encountered in borings B-102, B-103, and B-105. To the east of boring B-110 MW,the borings did not penetrate deep enough to encounter Cedar River alluvium. ' The beach deposit(Hb) is a coarse soil was deposited on beaches or created by wave action on beach lines in the Green/Duwamish River Embayment during a lower level of Puget Sound. The unit consists of very dense gravel; clean to slightly silty, sandy gravel or gravelly sand, with a trace of shell fragments. The unit is comprised of rounded to subrounded pieces of crystalline rock but with traces of basalt and red andesite and has a relatively medium to high permeability. ' The presence of shells fragments was confirmed in two borings, B-109 and 13- 205. The Duwamish/Green River Alluvium (HaD) is a fine-to medium-grained alluvial unit was deposited in the channels of the Green/Duwamish River and was not overridden by glacial ice. The unit consists of medium dense to very dense, ' clean to silty, fine sand and fine to medium sand, with scattered fine organics. It is comprised of subrounded to subangular pieces of dark gray to black basalt and red to red-brown andesite. It has a range of relative permeability from low to high. This alluvial deposit was found in all of the explorations and significantly thickens to the west of B-108 MWNWP. The Cedar River Alluvium—Gravel unit (Hag) is very coarse alluvial unit and was deposited from the ancient Cedar River after the last glaciation of the Puget Lowland. The unit consists of dense to very dense, sandy gravel and gravelly ' 4-7 Perteet inc. ' sand and contains scattered organics. The unit is comprised of rounded to subrounded particles of crystalline rock, typical of glacial deposits in the Cedar ' River Valley, and has a relatively high permeability. Drilling action indicated that there might be cobbles and boulders in this geologic unit. Two strata of this unit were encountered in the deeper borings (13-103, 13-105 VWP and 13-107) 1 separated by other alluvial layers about 15 feet thick. The Vashon advance glacial outwash (Qva) was deposited during the last glaciation of the Puget Lowland and was overridden by about 3,000 feet of glacial ice. This unit consists of very dense, gray, gravelly sand and was only encountered in the bottom of boring B-103. The unit is comprised of rounded to ' subrounded particles of crystalline rock and has a relatively high permeability. The drainage conditions are described in detail in the Surface Water Technical Discipline Report, Strander Boulevard Extension Project, (May 2004). Due to the flat topography at the project site, the risk of landsliding is very low. The Soil Survey of King County map (Snyder et al., 1973) was reviewed to approximate areas that may be susceptible to ' erosion when disturbed by construction. Soil units are considered to be erosion hazards if they are considered to be "severe" or"very severe"per the Woodland Groups, Wood Crops and Factors in Management of the Soil Survey. Table 4-1 presents the soil units, their geologic unit equivalents, and the level of erosion hazard. Figure 4-3 presents the Soils Map. Table 4-1: Erosion Hazard Units Soil Type Geologic Unit Erosion Hazard Newberg silt loam on slopes HaD/HeD Slight <2% Puyallup fine sandy loam on HaD/HeD Slight 1 slopes <2% Puget silty clay loam on slopes HeD Slight <1% Snohomish silt loam on slopes HeD Slight <2% Tukwila muck on slopes <1% HeD Slight Woodinville silt loam on slopes HaD/HeD Slight <2% ' Fill materials (Hf), also designated as urban land (Ur) in the King County soil survey, should be considered severe to very severe erosion hazards on slopes exceeding 15 percent. For temporarily exposed, unretained cut slopes in native soils, the erosion thazard would likely increase. In addition to the Soil Survey information, the City of Renton sensitive areas map for erosion hazards indicates that the entire proposed project area is within a low erosion hazard area. Figure 4-4 shows the flood hazard classifications. 4-8 1 Perteet Inc. ' The proposed project area between the West Valley Highway and Oakesdale Avenue has no existing drainage facilities, except for intermittent ditches on both sides of the two ' railroad tracks. Given the relatively flat terrain in this area(slopes < 1%) and several low spots (e.g., small, closed depressions), these ditches do not convey stormwater a significant distance; instead stormwater infiltrates into the ground. Up to seven existing storm outfalls and possibly two new outfalls might be affected or utilized by the proposed action (where outfalls are defined as point discharges into surface water bodies). These outfalls are presented in Table 4-2. This is where stormwater runoff currently discharges off of the roadway and into a water body. Other runoff locations from the project includes non-point sheet flow runoff, which is in the ' proposed alignment between Oakesdale Avenue SW and the West Valley Highway. ' Table 4-2: Existing and New Storm Outfalls Outfall Location Description Green River, Pipe outfall at river bank south side of Strander Boulevard Green River, —1,000 ft. south Pipe outfall at river bank (would only be of Strander Boulevard affected if stormwater were conveyed from the detention pond of the overpass to be discharged to the Green River) Wetland Location (not determined) east New pipe outfall into wetland (would be of roadway overpass in Renton' emplaced only if stormwater were conveyed from the detention pond of the overpass to be discharged to Renton wetlands in order to provide supplemental water per request of the City). Water Quality Pond at NE corner of Pipe outfall into pond of Oakesdale Ave & SW 27th Street rWater Quality Pond SW of Oakesdale New pipe outfall into new water quality Ave and SW 27`h Street (location not pond, with treated water discharging by determined)' pipe outfall into wetland at SW corner of Oakesdale Ave. & SW 27`h Street(would be emplaced only if stormwater were not ' conveyed to treatment and detention located within the right-of-way). Springbrook Creek, West Bank Pipe Outfall into Creek at SW 27th Street Springbrook Creek, East Bank Pipe Outfall into Creek at SW 27th Street Wetland at SW corner of SW 27th St. Pipe outfall into wetland' 4-9 Z 1 Perl :Inc. and Lind Ave 1 Storm Pipe System along E. Valley Rd. Storm pipe system along E. Valley Rd. then discharging into open ditch approx. 1,200 ft. north of SW 27th Street La This is the probable outfall location. The precise information on this outfall is not available at this time. Information in this table was updated since the publication of the Surface Water discipline Report, May 2004. Proposed Use of Property and Scope of Proposed Development The purpose of the project is to improve travel speed, reliability, and access in the north Renton/south Tukwila area. The project will create a cross-valley link between West Valley Highway (SR 181) and Oakesdale Ave. SW with a single roadway overpass will be constructed over both a relocated Union Pacific Railroad (UPRR) track and two ' Burlington Northern Santa Fe Railroad (BNSF) tracks. From Oakesdale Ave. SW to East Valley Road, SW 27th Street will be widened with pedestrian facilities and landscaping added. The project area will be approximately 100 acres. Access The majority of the roadway is designed to be in existing Tukwila and Renton right-of- ways. A small portion of the Sound Transit property will need to be acquired for the new roadway located within Tukwila's city limits, as the project will be providing a signalized intersection for access into the Sound Transit Station. The Boeing Company donated 176,171 square feet(or 4.04 acres) of right-of-way for the project, which will provide two signalized intersections for access to the Boeing Longacres Site. Proposed Off-Site Improvements (i.e., sidewalks, fire hydrants, sewer main, etc...) Due to the nature of this project, all improvements are considered off-site. The project will include an extension of a road that will create a cross-valley link between West Valley Highway (SR 181) and Oakesdale Ave. SW. As part of the road construction efforts, sidewalks, bicycle facilities, landscaping, sewer mains, water mains, fire hydrants, storm water management systems, and street lighting will also be constructed. The City of Renton is designing the water, sewer and fire suppression systems. They will be constructed in the right-of-way (ROW) and easements. The lines will not be larger than 12" in diameter. Perteet will be designing the road, sidewalks, bridge, lighting and storm water features, the site plans provided in Section 10 below show the proposed design of these features and eventually the City of Renton's design of the fire, water, and sewer features will be ' 4-10 Perteet Inc. included in these site plans. The current site plans provided in Section 10 show the proposed storm water system with the except of the features on the roadway overpass. The storm water design for the overpass will be discussed in the Supplement to the Hydraulics Report, which is currently being prepared for the City of Renton. The following is a general description of the improvements that will be completed as part of this project. ' Relocation of the Union Pacific Railroad Track The UPRR track will be shifted to the east to parallel the existing two sets of BNSF track. A new railroad track will be constructed within a new 100-foot right-of-way adjacent to the BNSF right-of-way and then joined with the existing UPRR track at both ends of the project area. Approximately 5,500 feet of new track will be constructed at an elevation similar to that of the existing BNSF tracks. Construction will require placement of 125,000 cubic yards of earth and gravel for the new railroad bed. The new UPRR track will be located at the center of the new 100-foot right-of-way. Approximately the same amount of track and railroad bed will be removed from the existing UPRR location as will be constructed at the new UPRR track location. The railroad bed material will be disposed of at an approved location or reused as a construction fill material. New Roadway Construction from West Valley Highway to Oakesdale Avenue SW A new roadway will be constructed from the intersection of West Valley Highway (SR 181) and Strander Boulevard to the intersection of Oakesdale Avenue SW and SW 27th Street. The roadway alignment will be an extension of Strander Boulevard and curve to match up with the existing alignment of SW 27th Street. This proposal features a roadway overpass that will be constructed over the two existing BNSF tracks and the new UPRR track. The overpass will provide vertical clearance of 23.5 feet for train clearance. From West Valley Highway to the overpass, the roadway will consist of five lanes (four thru lanes and a two-way left turn lane), landscaped strips, a sidewalk on the north side, and a shared use path on the south side. Bicycle facilities will be provided on the shared use path. The landscaped strips will be provided between the traveled way and the pedestrian facilities, and in some locations where a two-way left turn lane is not needed, a landscaped median will be provided. The overpass will not have the two-way left turn lane and planter strips. From the overpass east to Oakesdale Avenue SW, the same five- lane roadway, landscape strips, and pedestrian/bicycle facilities will be constructed. This section(including the roadway,pedestrian facilities and landscaped strips) will be 90 feet wide from back of sidewalk to back of sidewalk, staying within the appropriate existing City-owned right-of-way. The new roadway construction will result in three new intersections between West Valley Highway to Oakesdale Avenue SW. There will be one intersection at the future Sound ' 4-11 Perteet Inc. Transit Tukwila Station access road, and two intersections that will result from access roads to the Boeing Longacres site. New traffic signals will be installed at each of these intersections. Improvements to SW 27th Street The existing section of roadway between Oakesdale Avenue SW and East Valley Road ' will be widened to match that of the new roadway segment to the west (five lanes, landscaping strips, and pedestrian/bicycle facilities on each side). The section will be 90 feet wide from back of sidewalk to back of sidewalk, staying, for the most part, within 1 existing City-owned right-of-way. At some locations where there are space constraints or the need to avoid wetland impacts, the planter strip may be eliminated. Portions of the north side and south side of the proposed improvements may require a 3- to 8-foot block or rock wall at the back of the sidewalk to minimize impacts to the adjacent wetlands. A handrail will be required along the top of these wall sections. Modifications to the Interurban Trail The new roadway segment linking West Valley Highway and Oakesdale Avenue SW will j cut across the Interurban Trail. As a result, it will be necessary to construct a new means of making the trail continuous. The least obtrusive and preferred route is to have an at- grade crossing at either West Valley Highway or at the future Tukwila Station access road intersection. On the north side and the south side of the roadway, trail users will be routed onto the new bicycle/pedestrian facilities along the roadway, directed toward the intersection,cross the intersection, and then be directed back to the existing trail. Modifications to South Lon_gacres Way South Longacres Way, which is approximately 1,700 feet north of the intersection of Strander Boulevard and West Valley Highway, is bridged by the UPRR track and the BNSF tracks. It currently provides access to the temporary Sound Transit commuter rail parking area. The existing railroad bridges over South Longacres Way are narrow and 1 have lower vertical clearances than are now required for public roads. The relocation of the UPRR track will require the construction of a New UPRR Bridge. The new bridge will be constructed to provide the same vertical clearance. The BNSF bridge will not be reconstructed. Total Estimated Construction Cost The total estimated construction cost is $55 million. I 4-12 Perteet Inc. Excavation and Fill Material The roadway fill material will be gravel borrow. The cut volume for roadway will be 1 approximately 21,000 CY. The fill volume for roadway will be approximately 9,000 CY of gravel borrow. The railroad bed fill material will be comprised of gravel borrow and crushed rock. The fill volume for UPRR track bed will be approximately 125,000 CY. This material would be removed from the existing UPRR track bed, and either used as part of the needed fill 1 or disposed of appropriately. Tree Removal Plan A tree removal plan has not been prepared for this project, as the design is not yet complete and a detailed inventory of the vegetation in the area has not been completed. However, it is anticipated that some trees may need to be removed if they are within the area being developed or if they will be too close to the equipment being used for the project. Figures 10-2A through 10-21) show the proposed location of the road and related features. A description of the existing vegetation follows, per the Fish and Wildlife Technical Discipline Report, Strander Boulevard Extension Project, (May 2004). The undeveloped property within the project area is composed of several relatively large parcels that contain grass fields, shrubs, and deciduous forest. Wetlands are relatively abundant within the study area and consist of palustrine emergent (PEMC),palustrine shrub-scrub(PSSC), and palustrine forested (PFOC)types. During site visits, wetlands were identified and delineated in the study area and are described in detail in the associated Wetlands Discipline Report prepared for this project. In general, wetlands within the study area fall into two categories: linear palustrine wetlands characterized as ditch features along the railroad and large palustrine wetlands with a forested component 1 located along SW 27th Street. The only wetland along SW 27th Street that does not have a forested component is a shrub-scrub wetland developed as a mitigation site,which has young woody plants. The uplands consist of both open grass fields and deciduous forest. The open grass fields are typically clear of shrubs, often mowed, and level. Himalayan blackberry is frequently abundant in the fields and along the forested edges. Maintained planter strips with ornamental plantings are present throughout SW 27th Street. Red alder dominates forested areas and mature black cottonwood trees are scattered throughout. The shrub layer is diverse and varies considerably depending on location, but some of the species noted during field visits included beaked hazelnut (Corylus conruta),Nootka rose (Rosa nutkana), salmonberry (Rubus spectabillis), red elderberry (Sambucus racemosa), Pacific willow(Salix lucida), Sitka willow(Salix sitchensis), thimbleberry(Rubus parviflorus), and red-osier dogwood. Himalayan blackberry and reed canarygrass were very abundant in several areas. Land Dedicated to the City tA 90-foot wide parcel of land between the BNSF railroad and Oakesdale Avenue SW was dedicated to the city from Boeing as right-of-way for this project. 4-13 Perteet Inc. Proposed Job Shacks or Work Trailers During construction, contractors will utilize some type of job shack or work trailer(s). However, at this time, the contractor has not been selected, so it has not yet been determined how many or what type of structures will be used. Springbrook Creek Information Springbrook Creek(stream number 09-0005) flows south to north and bisects the project ' area along 27th Street SW between Oakesdale Avenue SW and Lind Avenue SW. Springbrook Creek generally flows northerly to the Black River Pump Station located near the intersection of I-405 freeway and the Valley Parkway. The creek and location of this pump station is shown in Figure 4-5. The pump station discharges into the Green/Duwamish River. This pump station has defined pump capacity restrictions, which regulate the flows in Springbrook Creek. The project area and the roadway will cross directly over the creek. Because the existing box culvert was sized large enough when it was installed to fully accommodate the road expansion, the only work that might occur below the ordinary high water mark(approximately 15.0' elevation) of Springbrook Creek would be the replacement of the two existing stormwater outfalls. A detailed description of Springbrook Creek is provided in the Fish and Wildlife Technical Discipline Report, Strander Boulevard Extension Project, (May 2004). Springbrook Creek is an approximately 12-mile-long stream, with an additional 23 miles of tributaries and drainage ditches, that enters the Black River at river mile (RM) 0.65 (Williams et al. 1975). Based on the results of a stream habitat assessment conducted by Harza(1995), the Springbrook Creek subbasin is composed of approximately 83 percent low-gradient glides, 13 percent riffles, < 1 percent pools, and < 1 percent step/run habitat types. DEA conducted stream habitat surveys along Upper Springbrook Creek(09-0020), Garrison Creek (09-0022), and a short section of the mainstem of Springbrook Creek (09-0005) where it runs parallel with SR 167 (DEA 2001). Based on the survey results, it was determined that glide habitat dominates all reaches west of SR 167, while riffle habitat dominates all reaches in the foothills to the east of SR 167. Pools, when present, tended to be relatively shallow and lacked habitat complexity. Furthermore, quality-spawning habitat is absent west of SR 167 but is available in the foothills where gradient increases. However, any salmonid that makes it through the BRPS must navigate through weed- choked segments of stream, numerous culverts, and depending upon time of year, potentially lethal water quality prior to reaching suitable spawning gravel in the foothills east of SR 167. Large woody debris (LWD) is basically nonexistent in the low-lying areas of Springbrook Creek west of SR 167 and is present but sparse in the forested foothills to the east of SR 167. The limited amount of LWD documented in Upper Springbrook Creek and Garrison Creek were composed of deciduous species and primarily in the small size category (DEA 2001) as defined by the U.S. Forest Service (USFS) stream survey protocol standards (USFS 2001). Due to the lack of mature conifer trees along the remnant riparian corridor, the availability of future LWD recruitment from riparian trees is nonexistent within the floodplain and limited in the ' foothills. 4-14 Perl :inc. Silt and sand are the dominant substrate type of all stream reaches located in the floodplain, while gravel is the dominant substrate type in the foothills (DEA 2001). However, some small pockets of gravel exist but tend to be embedded and intermixed with a very high percentage of fines. The results of Wolman pebble counts (Wolman 1954) conducted in Upper Springbrook Creek and Garrison Creek where gravel was the dominant substrate type indicated that fines (<0.24 inch)ranged from 29 to 39 percent in riffles (DEA 2001). The condition of the riparian corridor ranges from bare banks to remnant fragments of coniferous forest (Kerwin and Nelson 2000). Himalayan blackberry (Rubus procerus) and reed canarygrass (Phalaris arundinacea) are typically the dominant species along the stream corridor. Other species that are sporadically abundant and/or present include red alder(Alnus rubra), black cottonwood (Populus balsamifera), red-osier dogwood ' (Cornus sericea), Pacific dogwood (Corpus nuttallii), cattails (Typha latifolia), and several species of willow(Salix spp.). The condition of the riparian habitat improves in the foothills to the east of SR 167, where stream reaches flow through forested ravines. Within the forested ravines, red alder and big-leaf maple (Acer macrophyllum) become prevalent and are intermixed with black cottonwood, Douglas-fir(Pseudotsuga menziesii), western hemlock (Tsuga heterophylla), and western red-cedar(Thuja plicata). There should be no visual obstructions to Springbrook Creek as a result of this project. 4-15 Pertee 6 Inc. SEC. 19, T 23N, R 5E, W.M. SAC. 25, T 23N, R45E, VY.M. .,S LANGSTON RD AIRPORT S 133RD ST \ S 132N $ �FN S TON p — — CITY LIMIT ----- a \ S R/Y 9L TW Y i o! i 81oct U, J' RTyE.gN _!N'fP F E S 44TH ¢ x N { VALLEY �1Y SW '7TH ST So 7 " acos ORINGBR K - I 1a7rH �pp ; N sr ` TRAIL ;a S I = V o t 51 ST ST INTERURBAN S „ J 1 Z AVE S sw 1erH sr — - ' PRO ED UPRR RACK � BLV TUKw1LA PKWY wi EONGAOR S AY PROPOSEDO a r RO D AY LI ITS N o - - - Z ��� ; 'SPRIN OOK _ o al STRANDER c -�. - _ - TRAIL BL VD \ o -5W 27TH Sl' � STRANDER - TJ a BL D f— BNSF TkACKS( w UPRR T�ACK 1) ' G ST w w r co 0 W 34TH ST � a a � w Y Y K I � z a O O II? SW 41TH ST 7�Ty t Z sT s 180rH sr < 1sorH ST SE a3RD ST 180TH ST N INTE TRAIL R N ' \ �o ® City of Renton Figure 4-1 R E N T O N Strander Boulevard Extension Perteet Project Area ARM=: _ S % IDT r _ PROPOSED UPRR TRA(K' - _ _ Q -- - - BNSF TRACKS(2 U) —_S 34th S w - k Q) UPRR TR CK(1 > — 1 -_ Q co C/) i Y ' F—�Proposed UPRR Track Legend r_Proposed Extension Renton Zoning 1 City Boundary RC Resource Conservation Zoning Map Tukwila Zoning R-1 Residential LDR Low Density Residential R-8 Residential ��RCM Regional Commercial Mixed Use CA Commercial Arterial Figure 4-2 ^ TUC Tukwila Urban Center CO Commercial Office 'V ®C/LI Commercial Light Industrial IL Industrial-Light 0 500 1,000 2,000 IMIndustrial-Medium Pert eet I I IH Industrial-Heavy Feet Map created on 04/15/2004 N ' Wo �g I Ur o \ Ng \ Wo \ t Ur SVJ 27�4 Sheet 1 Q = r v Py 1 - 3 ? a Wo \ Pu So So T ConocnPbillrps r ink Fat U i T -- --- �- - - - — -_ o WO \� _ - — - I O10, a PROPOSED STRANDER BOULEVARD —� Q I Wo / SO I { 1L Pu So Tu m 1 East V I a aley Road CD / C a I Lcd A-P.��e SIN N 1 I 3 a nj 0 400 800 iu_ 0 Scale in Feet 1 SOILS EXPLANATION o Ng NEWBERG SILT LOAM: Well-drained soils formed in alluvium in the stream valleys. LEGEND U'' Approximate Location 1 : Wo WOODINVILLE SILT LOAM: Nearly level and gently undulating,poorly drained soils of Soil Type Boundary a, formed under grass, in alluvium,and on stream bottoms. o Ur URBAN LAND: Soil that has been modified by disturbance of natural layers with 1 additions of fill material. Geology and Soils Discipline Report 0 U) NOTES Strander Boulevard Extension w Py PUYALLUP FINE SANDY LOAM: Well-drained soils formed in alluvium,under grass, g hard woods,and conifers. 1. The soil type boundaries are adapted from The Soil Renton and Tukwila, Washington 1 o Survey of King County Area,Washington, 1973 by M So SNOHOMISH SILT LOAM: Poorly drained soils formed in alluvium in stream valleys. United States Department of Agriculture Soil o Conservation Service(Snyder and others, 1973). SOILS MAP N Pu PUGET SILTY CLAY LOAM: Poorly drained soils formed in alluvium,under grass,in m small depressions of the river valleys. 2. Base map adapted from drawings provided by Perteet 1 @ via the Buzzsaw website:22044EB.dwg,dated 8-22-03; May 2004 21-1-09369-002 o Tu TUKWILA MUCK: Very poorly drained organic soils fromed in decomposing vegetation. 22044pts.dwg and 22044ROW.dwg,dated 7-9-03. SHANNON &�IWInLSON, Iental NC. FIG. 4-3 Geotechnical and nts 1 N I I Zone AH I I Zone AE Zone AE �:C o Zone a Zone X Zone ConocoPhillips ifi I Tank Farm L ok w. . PROPOSED L Q Zone AE STRANDER BOULEVARD U Zone X y R � II o I ai m 01 a c - -4 0 0 o) cc c+� 0 o LEGEND 0 400 800 NOTES u; ' o Approximate Location of 1. The flood hazard boundaries are adapted from 3. The entire project alignment falls within a high Flood Hazard Boundary Scale in Feet the Flood Insurance Rate Map for King County, liquefaction hazard area. This conclusion is Washington and Incorporated Areas,Map No. based on conceptual design analyses and the a 53033CO978F by Federal Emergency map of Liquefaction Susceptibility of the Renton ' Management Agency. Quadrangle,Washington by the Washington Geology and Soils Discipline Report N FLOOD HAZARD EXPLANATION o Division of Geology and Earth Resources(1994). Strander Boulevard Extension Flood Hazard Areas for 100-Year Flood 2. This map illustrates flooding potential within the w Zone AE Event;Base Flood Elevation is About 20 Renton and Tukwila, Washington N Springbrook Creek drainage area. Flooding 4. According to the City of Renton sensitive areas g o Feet(NAVD88) potential within the Green River is contained Erosion Hazards Map(Palmer and others 1994), ' M within the dikes that border the river in this the entire project alignment falls within a low o Flood Hazard Areas for 100-Year Flood vicinity. The 100-year flood within the diked erosion hazard zone. HAZARDS MAP Zone AH Event;Flood Depths Could Range from 1 Green River is estimated to be at elevation 28 to 3 Feet feet as described in the report text. 5. Base map adapted from drawings provided by Perteet via the Buzzsaw website:22044EB.dwg, May 2004 21-1-09369-002 Flood Hazard Areas for 500-Plus-Year dated 8-22-03;22044pts.dwg and o ZoneX Flood Event 22044ROW.dwg,dated 7-9-03. SHANNON & WILSON, INC. FIG. 4-4 d GeolecAnical and Environmental Consultants LL Lo cn 4 z 2m U_ bi w F5 E cc cN 0 >1 w TI SW 16th St. ' .:� \ /i VALVE :�\� 31N 16th St. 48"RCP U) I 1 L�I 11'1 m z ca > ui U_ E 04 ca LLI 0 \ U q SVV 19th ',c*),t. EXISTING i tl / .. STORMWATER 4 m FACILITIES'.- LL PUMP ST 7r :J 4. Box 1100 CULVERT Jai_ SW 21 st S L. I'I C CD UJ c: CD > ------------ _0 ' C I y m W A? E. n > c% 2; ca 75 CD L_ 0 _0 co SW 23 4- 0 cu rd Sti. U) (D LU .............. -0 L) FF:,TE BASI S LU —0 z 200' cu mS V"A EY C/) LEGEND :t =3 a) T LU HIGHWAY BASIN C) (1) U) INTERMITTENT DIRECTIONAL FLOW PATH ' -( RAILROAD LLOEING=T SHEET FLOW & N > DRAINAGE FLOW PATH ST c Ae BASIN DRAINAGE BASIN If CONTRIBUTING OFF—SITE DRAINAGE BASIN 0 m WETLANDS (Flogged) 04 D —————200' SHORELINE BUFFER A OAKSDALE SPRING BROOK OHW BASIN CREEK BASIN (15') I — OHW (15') rn a ui IND AVENUE EAST VALLEY FA 'STING 4) OUTFALL IN BASIN HIGHWAY BASIN 27t 14-1, STREAM C NSTR�TED r h S\t c .5:, 4 ONO [Ek WES 1W 27th St.. SW 27th St. B SIN Z BOEING EAST FFSITE BASINS BASIN 0 r, ' �[ OU F LL 30W x 1 O'H BOX TO I ER CULVERT E �0.. E _f L ca OFFSITE BASIN W H z E cn ST. Q CONNECT TO 27TH 1p In .................... DETENTION PIT w 2-36"CONC STORMSEWER CULVERT 0 :_�' -- ------ SCALE p. _u cq ... SW � SW 29th St. ' .. . _ _' __C, to36o 150 o FEET 300 600