2720 ROCKEFELLER AVE 2024-03-29 - Laserfiche WebLink

California Street Parking Lot Stormwater Site Plan Report 1.2 MINIMUM REQUIREMENTS SUMMARY. This section summarizes compliance with the Minimum Requirements of the City of Everett Municipal Code and Stormwater Manual. Minimum Requirement #1: Preparation of Stormwater Site Plans: Full Drainage Plans under separate cover and this Full Storm Drainage Report addresses Minimum Requirement#1. Minimum Requirement#2: Construction Stormwater Pollution Prevention (SWPP): A construction Stormwater Pollution Prevention Plan (SWPPP) has be incorporated into the site development plans. The project site disturbance area is less than one acre and discharges to a combined sewer/stormwater system that is treated prior to discharge to the Snohomish River;therefore, a NPDES notice of intent (NOI) Department of Ecology(DOE) application is not required. SWPPP measures shall be applied during construction to reduce/eliminate sedimentation of the conveyance system and tracking of soils on the within the public rights-of-way. A summary of the site grading and erosion control measures is provided in Section 5 of this report and on the construction plans. Minimum Requirement#3: Source Control of Pollution: Specific source controls limited for a common vehicle parking lot. General requirements for residential sites include preventing the discharge of pollutants to the City's storm drainage system per Everett Municipal Code Chapter 14.40.050 (Prohibited discharges).This includes common items such as pesticides, herbicides, fertilizers, and fluids from vehicles. The proposed development will provide a stormwater collection system that will collect the surface stormwater runoff. Prior to discharge from the site a catch basin with a floatable materials separator and gas trap (per COE standard drawing 414) shall be provided. Construction Source Control Pollution are addressed within the construction SWPPP report (under separate cover). Minimum Requirement#4: Preservation of Natural Drainage Systems and Outfalls: On-site stormwater runoff flows in an easterly direction and enters the City's combined sewer/stormwater pipe system within the Rockefeller Avenue. The proposed site development will continue to discharge to the Rockefeller Avenue combined sewer/stormwater system along the easterly boundary of the site. See additional discussion of the site basin in Section 3 below. Minimum Requirement#5: On-Site Stormwater Management: The proposed site is currently covered by nearly 100% hard surface (existing building and gravel vacant lot);the proposed parking lot will result in about 12,524 sf of new/replaced hard surface with some limited vegetation areas surrounding the new parking lot area. Due to the site redevelopment(removed building replaced and fill materials) and adjacent buildings; no infiltration or dispersion BMP measures are proposed. The existing building and new parking lot will cover most of the site (+/-93%). The new parking lot area will be collected and routed to the city combined sewer/stormwater system along Rockefeller Avenue (east boundary of the site). See additional discussion in Section 4 for an evaluation of the stormwater control in the combined sewer/stormwater area of the City. The new pervious(landscape) areas shall be amended per DOE BMP T.5.13 Post Construction Soils Quality and Depth. Job#19-035 Page 1-2 RAM Engineering, Inc.