421 ROCKEFELLER AVE 2023-05-31 - Laserfiche WebLink

� r 4. SWPPP NARRATIVE The intent of this section is to provide the information necessary to support the engineering plans in order to implement a design that will; reduce, eliminate or prevent the discharge of stormwater pollutants, meet or exceed the water quality and sediment management standards for the City and State, and prevent adverse impacts to the receiving waters for this project. Note; this narrative is intended to support the SWPPP that is included with the Drainage Plans also a part of this submittal package to the City. A. SITE GRADING/EROSION CONTROL RISK ASSESSMENT Area proposed to be cleared/worked: 0.14 acres Average slope for the site: 3% (Area of Disturbance Only) Erosion Hazard of Soil Low Critical Areas downslope No Site is upstream of an ESA Stream No Based on the above information and the fact that the area of the site to be disturbed is flat and construction site runoff will pass through silt fencing or other perimeter filtration features prior to leaving the site, and that if site conditions warrant, additional BMP's can be implemented as corrective measures the Risk Category for this site is Low Risk. B. SWPPP MINIMUM ELEMENTS 1: Preserve Vegetation and Mark Clearing Limits The first step in the construction process is for the contractor to flag or fence the limits of clearing/disturbance (BMP C103) prior to any other construction activity. The engineering plans locate and provide the square footages for the areas of grading, clearing, impervious surfaces and un-disturbed areas on the proposed site. Approximately 90% of the project parcel will be cleared or disturbed for this project. 2: Establish Construction Access The SWPPP calls for a construction entrance to be installed off of the existing roadway to the west (Rockefeller Ave). At this time winter work is expected during the wet season. 3: Control Flow Rates This project is below the thresholds requiring flow control for the project. 4: Install Sediment Controls This site SWPPP proposes to maintain the existing asphalt entrance (BMP C105), vegetative buffer (BMP C102), silt fencing (BMP C233) if necessary and retention of the existing vegetation (BMP C101) that will provide a vegetated strip between the cleared areas and any property line. The construction of these features should be completed before the clearing and grading of the site. Mulch (BMP C121) will also be used on the exposed soil as necessary to limit erosion. In addition, streets shall be cleaned as needed at the end of each work day or throughout the day if dirt and debris is tracked onto the paved surfaces. Legion Lots 10& 11 20-0214 April 2020 Revised:April 2021 Page 6