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Home My WebLink AboutERC_Stormwater_Retrofit_Study_FINAL_220307DEPARTMENT OF COMMUNITY AND ECONOMIC DEVELOPMENT Project Location Map ERC_Stormwater Retrofit Study_FINAL ENVIRONMENTAL REVIEW COMMITTEE REPORT ERC Meeting Date: March 7, 2022 Project File Number: PR22-000002 Project Name: Stormwater Facility Retrofit Study Land Use File Number: LUA22-000040, ECF Project Manager: Jill Ding, Senior Planner Owner/Applicant: City of Renton; 1055 S Grady Way, Renton, WA 98057 Contact: Ken Srilofung, City of Renton, 1055 S Grady Way, 5th Floor, Renton, WA 98057 Project Location: Citywide Project Summary: A Non-Project Environmental (SEPA) Review is being requested for a Stormwater Retrofit Study. The City of Renton owns and maintains over 400 stormwater facilities to mitigate the stormwater impacts of development. Older stormwater facilities were primarily focused on providing stormwater storage. Design standards have advanced so that recently-constructed stormwater facilities provide better water quality treatment to mitigate the detrimental impacts of stormwater pollutants on stream water quality and aquatic habitat. The City received a grant from the Washington State Department of Ecology (DOE) to perform a study of many of the existing flow control facilities that have little or no water quality treatment features. The purpose of the study is to identify and prioritize the sites with the greatest potential to improve water quality. Exist. Bldg. Area SF: N/A Proposed New Bldg. Area (footprint): Proposed New Bldg. Area (gross): N/A N/A Site Area: N/A Total Building Area GSF: N/A STAFF RECOMMENDATION: Staff Recommends that the Environmental Review Committee issue a Determination of Non-Significance (DNS). DocuSign Envelope ID: AA732A77-1AE9-4064-B9A8-5210DA54C2A0 City of Renton Department of Community & Economic Development Stormwater Facility Retrofit Study Staff Report to the Environmental Review Committee LUA22-000040, ECF Report of March 7, 2022 Page 2 of 3 ERC_Stormwater Retrofit Study_FINAL PART ONE: PROJECT DESCRIPTION / BACKGROUND No actions are being taken at this time. This is a non-project action. The City of Renton (City) owns and maintains over 400 stormwater facilities constructed as far back as the 1970s to mitigate the stormwater impacts of urbanization. Between the 1970s and early 1990s, stormwater facilities were primarily focused on providing stormwater storage (i.e., detention). Since the 1990s, design standards have advanced so that today’s stormwater facilities provide better water quality treatment to mitigate the detrimental impacts of stormwater pollutants on stream water quality and aquatic habitat. These newer stormwater treatment systems target the removal of suspended solids, dissolved heavy metals, nutrients, and petroleum hydrocarbons. Typically, stormwater facilities owned by City connect to the municipal storm sewer system and drain to the closest water body. Taken as a whole, the older facilities in the City’s system are much less effective at protecting stream resources and water quality from pollutants than if the facilities included features required by today’s standards. The City received a grant from the Washington State Department of Ecology (WSDOE) to perform a study of many of the existing flow control facilities that have little or no water quality treatment features. The overarching goal is to improve the water quality in multiple creeks within the City that are part of the Cedar River/Lake Washington and Duwamish/Green watersheds. The study entails a series of six (6) sequential analytical tasks to be undertaken to prioritize the sites with the greatest potential to improve water quality. The first task, Task 1, was to select the existing facilities for evaluation: • Existing Facilities Selection (Task 1) –City staff selected 49 existing flow control facilities for this study primarily based on their understanding that these particular existing facilities provide minimal water quality treatment (see Figure 1 of Exhibit 3). The second task, Task 2, is this memorandum prepared by the WSP Team which includes: • Existing Conditions Summary (Task 2) -- This effort included collecting information about the 49 selected existing facilities. The summarized data includes: BMP type (stormwater best management practices are often referred to as “BMPs” in this memorandum), size, and age; tributary area characteristics; drainage basin information; and tracking of other information, which helps characterize existing facility information and can be used in future tasks to evaluate stormwater treatment performance and site-specific opportunities. These next tasks that are part of the study and will each be documented in subsequent technical memoranda include: • Treatment Gap Analysis (Task 3) -- This effort will identify deficiencies (gaps) in the treatment of stormwater at the facilities. This analysis will consider the needed treatment in comparison with treatment that would be provided using today’s stormwater design standards. • Retrofit Type and Opportunity Identification (Task 4) – This effort will build upon the treatment gap analysis to assess the types of opportunities available and the feasibility of retrofitting facilities to improve treatment performance. This will develop a preliminary suite of BMP types and sizes for each site. • Retrofit Opportunity Scoring and Prioritization (Task 5) – This effort will include the development of a method to screen retrofit opportunities to create a ranked list that focuses on the (a) highest benefit of water quality improvement and (b) most effective opportunities. • Conceptual Design of Highest Priority Sites (Task 6) – This effort will include the development of concept designs and cost estimates for the top three prioritized retrofit sites. PART TWO: ENVIRONMENTAL REVIEW In compliance with RCW 43.21C.240, the following environmental (SEPA) review addresses only those project impacts that are not adequately addressed under existing development standards and environmental regulations. DocuSign Envelope ID: AA732A77-1AE9-4064-B9A8-5210DA54C2A0 City of Renton Department of Community & Economic Development Stormwater Facility Retrofit Study Staff Report to the Environmental Review Committee LUA22-000040, ECF Report of March 7, 2022 Page 3 of 3 ERC_Stormwater Retrofit Study_FINAL A. Environmental Threshold Recommendation Based on analysis of probable impacts from the proposal, staff recommends that the Responsible Officials: Issue a DNS with a 14-day appeal period B. Mitigation Measures None C. Exhibits Exhibit 1: Environmental Review Committee (ERC) Report Exhibit 2: Environmental Checklist Exhibit 3: Stormwater Retrofit Study D. Environmental Impacts The proposed Plan is a non-project action and there are no adverse environmental impacts that are anticipated to occur in conjunction with the non-project proposal. In addition, there are no significant adverse impacts identified in review of the Environmental Checklist (Exhibit 2). The capital projects identified in the Plan would be required to comply with any applicable land use, development, environmental, and permit requirements at the time of application. E. Comments of Reviewing Departments The proposal has been circulated to City Department and Division Reviewers. Where applicable, their comments have been incorporated into the text of this report and/or “Advisory Notes to Applicant.” ✓ Copies of all Review Comments are contained in the Official File and may be attached to this report. The Environmental Determination decision will become final if the decision is not appealed within the 14-day appeal period (RCW 43.21.C.075(3); WAC 197-11-680). ✓ Environmental Determination Appeal Process: Appeals of the environmental determination must be filed in writing on or before 5:00 p.m. on March 21, 2022. Due to the ongoing state of emergency enacted by Governor’s Proclamation 20-05, the City Clerk’s Office is working remotely. For that reason, appeals must be submitted electronically to the City Clerk at cityclerk@rentonwa.gov or delivered to City Hall 1st floor Lobby Hub only on Tuesdays and/or Wednesdays. The appeal fee, normally due at the time an appeal is submitted, will be collected at a future date if your appeal is submitted electronically. Appeals to the Hearing Examiner are governed by RMC 4-8-110 and additional information regarding the appeal process may be obtained from the City Clerk’s Office, cityclerk@rentonwa.gov. DocuSign Envelope ID: AA732A77-1AE9-4064-B9A8-5210DA54C2A0 CITY OF RENTON DEPARTMENT OF COMMUNITY AND ECONOMIC DEVELOPMENT STAFF REPORT TO THE ENVIRONMENTAL REVIEW COMMITTEE EXHIBITS Project Name: Stormwater Facility Retrofit Study Land Use File Number: LUA22-000040, ECF Date of Meeting March 7, 2022 Staff Contact Jill Ding Senior Planner Project Contact/Applicant Ken Srilofung City of Renton 1055 S Grady Way, 5th Floor, Renton, WA 98057 Project Location Citywide The following exhibits are included with the ERC Report: Exhibit 1: Environmental Review Committee (ERC) Report Exhibit 2: Environmental Checklist Exhibit 3: Stormwater Retrofit Study DocuSign Envelope ID: AA732A77-1AE9-4064-B9A8-5210DA54C2A0