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HomeMy WebLinkAboutPN_Project_Narrative_BRPS_260707_v1 Memorandum King County BRPS – P3 Shoreline Exemption 1 King County Black River Pump Station - P3 Engine Replacement Shoreline Substantial Development Exemption Application Narrative & Code Analysis Date: June 18, 2026 Attention: Dan Brubaker, P.E. Company: King County DNRP; Water and Land Resources Division Prepared by: Emilie Wicker and Alexia Dorsch, Jacobs Project Name: King County Black River Pump Station Improvements – High Use Engines Property Owner/ Applicant King County Department of Natural Resources & Parks, Water & land Resources Division River and Floodplain Management Section Attn: Dan Brubaker, P.E. 201 S Jackson St, Suite 6300, Seattle, WA 98104 Project Location: 550 Monster Road SW, Renton, WA 98057 King County Parcels 377920-0090 & 722950-0281 Site Area: 322,570 square feet (7.41 acres) Zoning: RC (Resource Conservation) - Parcel 377920-0090 & 722950-0281 RC, CO, IH, IL, IM – zoning of surrounding properties Current Use: Black River Pump Station and associated infrastructure. No change in use is proposed. Site Features: Black River (Shoreline of the State, Type S water) Four (4) Wetlands (no impacts proposed, all work within existing pump station footprint) Soil Type & Drainage Conditions: Soils at the BRPS consist primarily of non-native fill that was placed at the site during original construction of the pump station. Native soils below the top layer of imported fill consist of Woodinville silt loam and Puyallup fine sandy loam. Banks on both sides of the river are steep, with retaining walls upstream and downstream of the pump station. Runoff from impervious surfaces drains to the Black River and is limited to pump station building and rooftop runoff. The southern portion of the site is sloped towards Monster Road SW, where runoff is collected in an open ditch and outlets into the Black River. Construction Cost: $1,468,348 Overall Costs Nature of Existing Shoreline: There is minimal vegetation within the fenced yard of the pump station. Banks on both sides of the river are steep, with retaining walls upstream and downstream of the pump station. Farther downstream, banks are steep and heavily armored with riprap. Vegetation is dominated by Himalayan blackberry. The Black River Pump Station impounds water behind the dam, creating a large, slow-moving pool that flows through the City’s Black River Riparian Forest and Wetland. Banks in this area are more gently sloped, and heavily vegetated with primarily native species of mature trees and shrubs Shoreline Designation: Natural Environment - Black River/ Springbrook Creek Jurisdiction, Reach A (BRSC- A) Memorandum King County BRPS – P3 Shoreline Exemption 2 Project Description The applicant, King County Department of Natural Resources and Parks, Water and Land Resources Division, in coordination with the King County Flood Control District, is requesting a Shoreline Exemption to replace an existing pump engine and associated cooling water equipment of the Black River Pump Station (BRPS). The BRPS is located on a concrete dam that spans the Black River channel, conveys all Springbrook Creek flow to the Green River, and is a critical component of the Green River flood control system. The pump station protects against significant flood damage that could occur if the Green River flood flows back up in the Black River. The BRPS has operated continually since it was constructed in 1972 and includes eight flood control pumps: one electric motor-driven pump (P1) and seven diesel engine-driven pumps (P2-P8). The primary function of the BRPS is to pump river water from the Black River to the Green River under normal conditions, as well as to contain the Green River and protect floodplain properties during flood conditions. Repair of other High-Use Pumps (P1, P2 & P4) and replacement of associated high-use diesel engines and electric motors was completed under the current construction contract and approved under LUA20-000089. Under this exemption request, King County proposes to replace the engine associated with Pump P3 with a new, modern, and automated engine, along with a dedicated equipment cooling water (ECW) pumping system (currently identified as P12, replacement pump identified as P16), to properly support future construction and operational needs and to preserve the existing pump station capacity. The P3 engine needs to be automated and more reliable because it will drive the only large pump available during a period of construction starting under a future contract. The replacement of P12 with P16 will allow ECW to be pumped from the south half of the station, rather than relying solely on ECW from P11, which is in the north portion of the engine room. The existing Pump P3 engine, concrete pedestal, and equipment will be demolished, to make room for the installation of the new engine. The new engine requires a larger 12-inch exhaust manifold and silencer, so the existing 10-inch exhaust will also be replaced. The existing structural frame supporting the silencer will be reused, with minor support modifications. Pump P3 does not require any refurbishment, only the replacement of the engine, concrete pedestal, and associated equipment within the pump station structure. All this work is above the normal forebay water level. The replacement of P12 with P16 is the only in-water work associated with this application. All other construction work will be contained within the existing fenced areas north and south of the pump house, with most work taking place within the existing structure at the pump station. King County issued a SEPA determination of non-significance (DNS) for this proposal under WAC 197-11- 340(2) on March 26, 2020, and two revised DNS on April 13, 2020, and June 1, 2026. (See attached.) RMC 4-3-090.F.5.a, establishes review criteria for permitted flood control projects; the applicable criteria are addressed below: Review of Shoreline Exemption Regulations RMC 4-3-090– Environmental Regulations & Overlay Districts – Shoreline Master Program Regulations Under RMC 4-3-090.F.5.a, Permitted Flood Control Projects – “Flood control works shall be permitted when it is demonstrated by engineering and scientific evaluations that: i. They are necessary to protect health, safety and/ or existing development; ii. Nonstructural flood hazard reduction measures are infeasible; and iii. Measures are consistent with an adopted comprehensive flood hazard management plan that evaluates cumulative impacts to the watershed system.” The proposed pump P3 engine and pump P12 replacement with P16 are within the Black River Pump Station (BRPS), which is located on an existing concrete dam spanning the Black River channel. The pump station conveys all Springbrook Creek flow to the Green River and is a critical component of the Green River flood control system. The station has operated continually since it was constructed in 1972 and includes eight flood control pumps (P1-P8). The primary function of the BRPS is to pump river water from the Black River to the Green River under normal conditions, as well as during flood conditions as defined by the Green River Management Agreement of 1985 (Green River Basin Program 1985). The pump station protects against significant flood damage that could occur on developed lands in Renton, Kent, and Tukwila if the Green River flood flows back up in the Black River. Memorandum King County BRPS – P3 Shoreline Exemption 3 King County is proposing to replace the P3 engine, concrete pedestal, and associated equipment within the pump station structure. The ancillary equipment cooling water pump P12 that served the existing High-Use right-angle gear drives (but never functioned properly and has been inactive for decades) will also be replaced in the same location with a new equipment cooling water pump (P16) to provide necessary cooling to the new P3 engine and existing P3 right-angle gear drive. The replacement of P12 with P16 is the only in-water work associated with this application. The work will preserve the existing pump station flood discharge capacity. The P3 engine exhaust pipe on the exterior of the pump house will also be replaced. The proposed P3 pump engine and P12 replacements to BRPS are considered normal maintenance or repair of existing structure or developments. In addition, the existing pump engine will be replaced with a new engine that meets US Environmental Protection Agency (USEPA) Tier 2 emission standards, resulting in much cleaner combustion and better efficiency than the existing 50+ year old engine. RMC 4-9-190 – Permits Specific - Shoreline Permits RMC 4-9-190.C.1.c outlines the shoreline substantial development exemption criteria for Maintenance and Repair as: Normal maintenance or repair of existing structures or developments, including damage by accident, fire or elements. i. “Normal maintenance” includes those usual acts to prevent a decline, lapse, or cessation from a lawfully established condition. ii. “Normal repair” means to restore a development to a state comparable to its original condition, including but not limited to its size, shape, configuration, location and external appearance, within a reasonable period after decay or partial destruction, except where repair causes substantial adverse effects to shoreline resource or environment. iii. Replacement of a structure or development may be authorized as repair where such replacement is the common method of repair for the type of structure or development and the replacement structure or development is comparable to the original structure or development including but not limited to its size, shape, configuration, location and external appearance and the replacement does not cause substantial adverse effects to shoreline resources or environment. The proposed development meets the criteria above, is consistent with the City of Renton Shoreline Management Program and the State Shoreline Management Act and should be considered exempt from a Shoreline Substantial Development Permit.