Otak 11/23/2020 - Laserfiche WebLink

• Workshop with City to decide which receiving water is to be analyzed for basins with more than one receiving water. • Workshop with City to review the draft methodology on the "pilot" basin. • Update narrative in basin plans to state whether TSS, nutrients, metals and fecal coliform are pollutants of concern. • Update section titled Analysis of Stream Health Based on Data and Pollutant Sources where applicable with existing and proposed zoning graphs (e.g. pie chart or stacked bar chart), and a narrative describing untreated area in the basin based on extent of treatment provided by existing BMPs. • Add section to provide a narrative identifying whether stormwater management techniques, such as structural retrofits, enhanced stormwater management actions, and non-stormwater management actions may be used to address pollutants of concern. • Add section about development pressures in the basin. • Add an Environmental Justice section to each basin plan, populated with USEPA's EJ Screen analysis and narrative. Everett • Update land cover figure for each basin plan. • Provide working development pressures map per watershed • Update Waterbody Monitoring Data—Water Quality Data section for each basin plan. • Provide map for chapter 2 in each watershed plan showing overburdened communities. 230 Assess Stormwater Management Influence This task corresponds to Steps 3 on page 7 of the SMAP Guidance. The purpose of this task is to provide the rationale for sorting the receiving waters according to their relative expected benefit from SMAP. This task will assess stormwater influences on stream hydrology and stream pollutants as follows: 1. Stormwater Management Influence on Stream Hydrology. Otak will develop a methodology for rating influence on hydrology using the following elements: a. Flow-control exempt receiving waters from the 2017 SWCP b. Classifications of streams, if available from the 2017 SWCP or from updated information from WDFW or City Planning. c. If receiving waters primarily influenced by groundwater flows, if available from the 2017 SWCP. d. The impervious area in the basin and/or fraction of MS4 discharging to the receiving water. 2. Stormwater Management Influence on Water Quality. Otak will develop a methodology for rating influence on hydrology using the following elements: a. Monitoring data analysis completed in Task 220 i. Example: The City's MS4 will be considered to have a high influence on receiving waters where TSS and/or metals exceed the water quality standard. b. Fraction of pollutant generating surfaces with limited existing treatment calculated based on zoning and an approximation of area treated using BMPs. Any areas that are to be up-zoned will be assumed to be treated as they will have to meet regulatory requirements for water quality. i. Example: If 25 percent or more of the basin is believed to be covered in either commercial- industrial surfaces, or high-density residential land uses without treatment, pollutant-generating surfaces will be considered to have a high influence on pollutant loads in the stream. c. Presence of City owned roads with ADT> 7,500 with limited existing treatment d. Point sources (commercial and industrial areas) e. Fraction of Everett's MS4 in relation to the entire basin 3. List of basins where the City's MS4 has a low influence on hydrology and water quality will not be considered further in the prioritization process. Receiving Waters Assessment and Update of Surface Water Comprehensive Plan 5 Scope of Work Otak