2702 59TH ST SW 2024-07-05 - Laserfiche WebLink

DRAINAGE REPORT Miller Residence Drainage June 2023 MINIMUM REQUIREMENT #1: PREPARATION OF STORMWATER SITE PLANS The Stormwater Site Plan was prepared in accordance with Volume 1, Chapter 3 of the SWMMWW and includes the minimum requirements applicable to the subject site based on the thresholds of new and replaced site impervious coverage. This document shall serve as the Stormwater Site Plan for this project. The Project Plans submitted separately supplement this document and are referred to herein. The civil project plans are attached to this report in APPENDIX A. MINIMUM REQUIREMENT #2: STORMWATER POLLUTION PREVENTION PLAN (SWPPP) The Construction Stormwater Pollution Prevention Plan, which complies with the required elements outlined in Volume I, Section 2.5.2 of SWMMWW is provided in the Project Plans submitted separately and serves as a guide for the contractor to implement a final Temporary Erosion and Sediment Control (TESC) Plan. See Section 5 of this report for additional SWPPP details. 4.0 OFF -SITE ANALYSIS An off -site analysis was not provided due to the proposed runoff will sheet flow to a dispersion trench. 5.0 STORMWATER POLLUTION PREVENTION PLAN (SWPPP) The project is anticipated to disturb less than the threshold requirements of land disturbing and therefore requires the consideration of a SWPPP in compliance with the elements listed in Section 2.5.2 of Volume I of the Washington State Department of Ecology's SWMMWW. Temporary erosion and sediment control measures are shown in the Project Plans, submitted separately. Each of the 13 required elements of the SWPPP are addresses below: ELEMENT NO. 1—MARK CLEARING LIMITS To protect adjacent properties and to reduce the area of soil exposed to construction, the limits of construction will be clearly marked before land -disturbing activities begin. The BMPs relevant to marking the clearing limits that will be applied for this project may include: • Buffer Zones (BMP C102) • High Visibility Plastic or Metal Fence (BMP C103) ELEMENT NO. 2 — ESTABLISH CONSTRUCTION ACCESS Construction activities occurring on unpaved areas shall be minimized and construction vehicle access will be limited to one entry, constructed according to SWMMWW standards, as depicted in the plan set attached to this report. The proposed construction access is located off 59t" Street SW and is shown on the TESC plan. Street sweeping and street cleaning shall be employed to prevent sediment from entering the roadway or the roadway drainage system. The specific BMPs related to establishing construction access that will be used on this project include: • Stabilized Construction Entrance (BMP C105) XG/Watershed 20230616 Miller Drainage Report FINAL Page 7