10306 27TH DR SE 2021-12-15 - Laserfiche WebLink

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 County and State, and prevent adverse impacts to the receiving waters for this project. A. SITE GRADING/EROSION CONTROL RISK ASSESSMENT Area proposed to be cleared/worked: Average slope for the site: Erosion Hazard of Soil Critical Areas downslope Site is upstream of an ESA Stream 0.13 acres 5% (Area of Disturbance Only) Slight No 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 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. As much of the natural vegetation as possible will be preserved on this project (BMP C101). Approximately 65% of the site may be cleared or disturbed for this project. 2: Establish Construction Access The SWPPP calls for the existing gravel to be used as the construction entrance. 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 for the existing gravel to be used as the construction entrance. A vegetative buffer (BMP C102), silt fencing (BMP C233) and retention of the existing vegetation (BMP C101) will provide a vegetated strip around the work area and any adjacent 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. 271h Dr SE - Haack 19-ubub May 2019 Page 6