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HomeMy WebLinkAboutSPU BCF_Geotech Shoreline Exemption Request.pdf Page 1 of 5 To: Alex Morganroth, City of Renton Copies: Michael Norton and Clay Antieau, Seattle Public Utilities Derek Nelson, McMillen Jacobs Associates From: Ryan Crotty and Tessa Gardner-Brown, Floyd|Snider Date: July 16, 2020 Re: Shoreline Permit Exemption Request for Focused Geotechnical Investigation 1.0 Purpose Seattle Public Utilities (SPU) seeks a shoreline letter of exemption to conduct a focused geotechnical investigation to assess subsurface conditions within the Cedar River at the site of the existing sockeye salmon broodstock collection facility (BCF). The information gathered during the geotechnical investigation would inform future upgrades to the BCF and construction approach. A previous geotechnical investigation was completed in 2019 for upland portions of the existing BCF site (refer to LUA19-000013 for the associated shoreline exemption). Both the proposed and former geotechnical investigation are exempt from review under the State Environmental Policy Act per WAC 197-11-800.17. 2.0 Project Location The site subject to the requested shoreline exemption is located below the ordinary high water mark (OHWM) of the Cedar River at the existing BCF site (river mile 1.7) in Renton, Washington, located immediately upstream of the Interstate 405 Bridge (Project Site). Two borings would be collected within the Cedar River (172305HYDR) and one contingency boring could be collected below the OHWM on City of Renton-owned parcel 1723059014. Refer to the Proposed Project’s site plan for more details (Attachment 1). 3.0 Existing Site Conditions 3.1 Land Uses The current land use to the north of the Cedar River includes the City of Renton Cedar River Park and Community Center. The current land use to the south of the Cedar River includes the Cedar River Trail and a concrete boat ramp/driveway that provides public access to the Cedar River. The geotechnical investigation would not interfere with the normal use of either the Cedar River Trail or the City of Renton Cedar River Park or Community Center. City of Renton July 16, 2020 Shoreline Permit Exemption Request for Focused Geotechnical Investigation Page 2 of 5 3.2 Natural Features and Shoreline Conditions A Biological Assessment prepared in 2008 for the existing BCF characterized this reach of river as entirely artificial, completely constrained between levees and revetments, and was regularly dredged to prevent flooding from 1916 to the mid-1970s. Within this reach, urban and industrial development have impaired water quality, eliminated natural floodplain connections and riparian corridors, and reduced the amount of large woody debris. This reach is the depositional area for many of the river’s sediments, resulting in higher levels of fine sediments than upstream areas. 4.0 Project Description SPU proposes to collect up to three in-water geotechnical borings (two planned borings, one contingency boring) within the Cedar River. The borings would be completed using a sonic drill rig, floated to the proposed boring locations using a portable barge made up of four 10-foot by 20-foot sections that would be assembled on-site, creating a 20-foot by 40-foot barge. When the barge is launched, dimensional lumber (likely 2 inches by 14 inches) would be placed at the base of the existing access ramp. The lumber would serve as wheel tracks, allowing the portable barge to be placed in water deep enough to accommodate its draft, approximately 17 inches. The lumber would be removed after the barge is launched (after 2 to 4 hours) and placed again and removed when the barge is retrieved from the river. The barge would be anchored on the north side of the river using a typical boat anchor or a 2-inch-diameter steel rod; both techniques would avoid the existing rock wall. On the south side of the river, the barge would use either anchor rods or a strap tied to a tree. The sonic drill rig would bore 6-inch-diameter holes to a maximum depth of 35 feet below ground surface, or until bedrock, whichever is encountered first. Once a hole has been drilled, a screen would be temporarily inserted to assess the porosity of the subsurface conditions. Cores extracted from the bore holes would be taken upland for processing; drill cuttings would be placed in drums for disposal at an appropriate upland location by the subcontractor. After data collection is complete, the bore holes would be decommissioned consistent with Washington State Department of Ecology-approved methods. The geotechnical investigation is anticipated to take up to 3 days (1 day per boring) in July or August 2020. Other approvals that would be required before the geotechnical investigations could include a State Environmental Policy Act exemption, Washington Department of Fish and Wildlife Hydraulic Project Approval, and U.S. Army Corps of Engineers concurrence that no permit is required given that the activities would not discharge fill below OHWM. The anticipated cost for the geotechnical investigation is approximately $76,000. City of Renton July 16, 2020 Shoreline Permit Exemption Request for Focused Geotechnical Investigation Page 3 of 5 5.0 Exemption Type According to Washington Administrative Code (WAC) 173-27-040(2)(m) and Renton Municipal Code (RMC) 4-9-190(C)(12), investigation work within shoreline jurisdiction, which is necessary to support future development applications, is considered exempt from the need to obtain a shoreline permit. The geotechnical investigation is being conducted to support the design of a replacement BCF, for which SPU is currently preparing permit applications. For this reason, the geotechnical investigation work would qualify for a shoreline letter of exemption by state law and the locally adopted Shoreline Master Program (SMP). Although the geotechnical investigation is exempt from the need to obtain a shoreline permit, all shoreline activities, exempt or not, must be consistent with the locally adopted SMP and Shoreline Management Act (SMA). Therefore, a brief consistency analysis between pertinent SMP and SMA regulations and the work is provided below. 6.0 Consistency with Pertinent Shoreline Management Regulations 6.1 Shoreline Management Act According to the SMA’s specific regulations regarding shoreline exemptions for site investigation work that is necessary to support future development applications, codified under WAC 173-27- 040(m)(i-v) and RMC 4-9-190(C)(12), the following prerequisites must be met for investigation work to be categorized as exempt per SMA standards: i. The activity does not interfere with the normal public use of the surface waters; The proposed geotechnical investigation would not result in the construction of a structure or permanent alteration of land that would preclude the public’s normal use of the Cedar River or the surrounding environment. The geotechnical investigation is anticipated to last up to 3 days. This work would occur during the standard weekdays, avoiding times of peak recreational use at and around the Project Site. The work would not occur during City of Renton planned community events. Due to the short duration, the geotechnical investigation would result in negligible interference to the public’s use of the Cedar River. ii. The activity will have no significant adverse impact on the environment including but not limited to fish, wildlife, fish or wildlife habitat, water quality, and aesthetic values; The geotechnical investigation would not have a significant adverse impact to the shoreline environment. Work would be conducted below the OHWM of the Cedar River; however, project impact would be limited to no more than three 6-inch-diameter bore holes that would be naturally restored after the investigation is complete. The following best management practices would be implemented to minimize impacts to habitat or water quality: • Work will be completed during the allowable in-water work window (July 1 to August 31). City of Renton July 16, 2020 Shoreline Permit Exemption Request for Focused Geotechnical Investigation Page 4 of 5 • A casing will be used to contain the boring operation to prevent sediments or other materials from entering the water. • All waste material from this project will be disposed of at an approved upland location. • Drilling equipment will be checked daily for leaks and be well-maintained to prevent grease, lubricants, or other deleterious materials from entering state waters. • Drilling equipment will be supported by a barge on the river to minimize contact with surface waters. • Bore holes will be decommissioned consistent with Washington State Department of Ecology-approved methods. • A Spill Prevention, Control, and Countermeasure Plan will be developed and implemented that prevents any potential contaminants associated with construction from entering water bodies in the project vicinity. There is no potential for long-term aesthetic impacts because the bore holes would be decommissioned and natural river bedload movement would restore the riverbed to its original condition once investigation work is complete. iii. The activity does not involve the installation of any structure, and upon completion of the activity the vegetation and land configuration of the site are restored to conditions existing before the activity; As stated previously, the geotechnical investigation would not result in the permanent installation of a structure. Furthermore, the disturbed riverbed would be naturally restored to its original condition once the investigation activities are complete. iv. A private entity seeking development authorization under this section first posts a performance bond or provides other evidence of financial responsibility to the local jurisdiction to ensure that the site is restored to preexisting conditions; and The applicant is a public agency. The disturbed riverbed would be restored naturally by river deposition once investigation work is complete. v. The activity is not subject to the permit requirements of RCW 90.58.550; The permit requirements outlined in RCW 90.58.550 pertain to oil or natural gas exploration in marine waters. The Proposed Project is not subject to these requirements. 6.2 City of Renton Shoreline Master Program A consistency analysis between pertinent City of Renton SMP development standards that apply to all activities within the shoreline (RMC 4-3-090(D)), and the geotechnical investigation is provided below. City of Renton July 16, 2020 Shoreline Permit Exemption Request for Focused Geotechnical Investigation Page 5 of 5 Environmental Effects The following measures would be taken to ensure that the Proposed Project would result in no net loss of ecological function: 1. The extent of disturbance would be kept to the minimum practicable to conduct the geotechnical investigations. The geotechnical investigation would not require more than three total bore holes. Disturbance would be limited to a hole diameter of approximately 6 inches. No other earthwork is proposed. 2. The geotechnical investigation would not alter/remove trees or vegetation along the shoreline or within the river. 3. Bore holes would be decommissioned in accordance with methods approved by the Washington State Department of Ecology. 4. Disturbance would be limited to a maximum of 3 days. In addition to the no-net-loss requirement for any development or activity within shoreline jurisdiction, RMC 4-3-090(D)(2)(c) includes a provision that requires compliance with the City of Renton’s critical areas regulations even if the subject activity is exempt from a shoreline development permit. Because the geotechnical investigation would occur within the Cedar River, compliance with the RMC’s critical areas regulations is required. According to the exempt activities table in the City of Renton’s critical areas regulations (RMC 4-3-050(C)), site investigative work necessary for land use application submittals such as surveys, soil logs, percolation tests, and other related activities is considered an activity exempt from the critical areas regulations, provided that the investigative work does not disturb more than 5 percent of the critical area and associated buffer. This regulation also requires impacts to be minimized and disturbed areas to be immediately restored at a one-to-one ratio. The geotechnical investigation would disturb significantly less than 5 percent of the Cedar River within the Project Site, and all disturbed areas would be naturally restored to their original condition once the data have been retrieved from the bore holes. 7.0 Conclusion As demonstrated in this narrative and the supporting materials that compose the application package, the proposed geotechnical investigation activities are compliant with applicable provisions from the SMA and City of Renton SMP. Therefore, SPU respectfully requests issuance of a shoreline letter of exemption. LIST OF ATTACHMENTS Attachment 1 Site Plan and Neighborhood Map !( !( !( §¨¦405 Cedar River C e d a r R iverParkDrHouser Way NCedarRiverTrail Parcel ID:1723059014 50 4035 55 55 6065707580 35 50 55 45 40 4035 30 30 45 I:\GIS\Projects\MJA-SPU-BCF\MXD\Cedar River Sockeye Hatchery Broodstock Collection Facility Geotechnical Exploration Phase 2\Site Plan and Neighborhood Map.mxd7/16/2020 Site Plan andNeighborhood Map Seattle Pu blic U tilitiesBroodstock Collection FacilityGeotechnical InvestigationRenton, WA Legend !(In-water Geotech Boring !( Contingency In-waterGeotech Boring OHWM 5-ft Elevation Contour Parcel of Interest Shoreline Jurisdiction Abbreviations: bgs = Below ground surface ft = Feet OHWM = Ordinary high water mark ProjectArea Seattle Renton 0 120 24060 Scale in Feet ¹ Notes: · Geotech borings will be up to 35 ft bgs. · Parcel boundary and 5-ft elevation contours obtained from King County GIS. · Aerial imagery obtained from Nearmap, 2020. · Inset basemap tiles by Stamen Design, under CC BY 3.0. Data by OpenStreetMap, under ODbL.