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2. EXISTING CONDITIONS SUMMARY <br /> The site covers approximately 1.12 acres. The proposed disturbance area of the existing <br /> site has not changed notably since 1997 and consists of a SFR, detached garage, shed, <br /> asphalt driveway, flat landscaping and steep forested slopes. The existing SFR will be <br /> removed from the site and the existing driveway will be widened with the existingdriveway <br /> surface receiving an overlay in the area of the access. Therefore, the overlay of the <br /> existing driveway is not considered a replaced surface and all of the remaining proposed <br /> impervious surfaces will be considered new. The proposed improvements for this project <br /> include the removal of the existing house, installation of a new house on each new lot and <br /> driveway additions to serve the 2 new lots. This project proposes to increase the on-site <br /> impervious surfaces by approximately 9,613 sf(0.22 Ac). This project does not propose <br /> any clearing or grading within the steep slopes of the project parcel. <br /> The overall slope of the short plat is down and to the north. The proposed disturbance <br /> area averages less than 5% and the steep slopes are greater than 40%. The existing <br /> roadway Gibson PI., is able to sheet flow runoff onto the project site. This runoff is <br /> immediately collected by landscape flower beds and is not expected effect the project <br /> area. This project will not affect any offsite flows from passing through or around the site <br /> as in the existing conditions. All runoff from the proposed developed hard surfaces on this <br /> site will be collected and conveyed to the toe of the bluff to the north via an 8" conveyance <br /> system with diffuser tee. The discharge location will be on the south side of the BNSF <br /> railroad with Puget Sound located to the north. Therefore, the runoff will be discharged at <br /> a location where it will flow through the existing ditch system for the railroad and then <br /> through an existing culvert into Puget Sound which will have negligible impact on the <br /> downstream existing conditions. <br /> Based on the existing soil information and the setbacks of the proposed improvements <br /> from any of the property lines or critical areas there is little potential for erosion or <br /> sedimentation during construction, assuming the basic BMPs included in the SWPPP are <br /> installed and maintained properly. Refer to Figure 2 for an existing basin map. <br /> Robinett Short Plat 15-0403 <br /> Revised:April,2016 Page 5 <br />