15 FERN RD 2017-10-30 - Laserfiche WebLink

2. EXISTING CONDITIONS SUMMARY The site covers approximately 0.20 acres. The site in the existing conditions currently consists of an existing SFR, shop, driveway, and lawn. The existing structures are to either be removed or replaced, therefore the total net increase in impervious surfaces is only 782 sf. Access to the site will be from the end of the existing road to the south (Fern Rd). Approximately 4,195 sf (0.10 acres) of the site will be impacted by new impervious surfaces with the entire site, approximately 8,900 sf (0.20 acres) being disturbed as needed for the clearing/grubbing and restoration of the existing site. The proposed area of disturbance is the entire site. The proposed area of disturbance appears to drain to the east. The existing roadway to the south drains to the vegetated right-of-way of Fern Rd. This project will not affect any off-site flows from passing through the site as in the existing condition. All of the proposed impervious surfaces for this project will be either be dispersed via splash blocks or sheet flow with the minimum required flow path over vegetated surfaces or tightlined to a perforated stub-out connection and connected to the existing stormwater system within the right-of-way. See Section 7 of this report for more details. Soil logs were provided by Ryan Kramer. See Appendix `A'. Soil conditions for the site were determined to be sandy loam with a depth to hard pan of 31-43 inches below grade. The USDA Web-Soil Survey was used to determine the existing soil conditions for the parcel. The soils are mapped as Alderwood-urban land complex. The general site slopes, in the area of disturbance, are flat and average less than 5 percent down to the east. Based on the existing soil information and the setbacks of the proposed improvements from any of the property lines or critical areas there is little potential for erosion or sedimentation during construction, assuming the basic BMPs included in the SWPPP are installed and maintained properly. Refer to Figure 2 for an existing basin map. 15 Fern Rd Duplex 16-0302 REVISED: June 2016 Page 4